xref: /btstack/src/ble/gatt_client.c (revision 8450fbf5264226cc028949233b289d9e05776193)
1 /*
2  * Copyright (C) 2014 BlueKitchen GmbH
3  *
4  * Redistribution and use in source and binary forms, with or without
5  * modification, are permitted provided that the following conditions
6  * are met:
7  *
8  * 1. Redistributions of source code must retain the above copyright
9  *    notice, this list of conditions and the following disclaimer.
10  * 2. Redistributions in binary form must reproduce the above copyright
11  *    notice, this list of conditions and the following disclaimer in the
12  *    documentation and/or other materials provided with the distribution.
13  * 3. Neither the name of the copyright holders nor the names of
14  *    contributors may be used to endorse or promote products derived
15  *    from this software without specific prior written permission.
16  * 4. Any redistribution, use, or modification is done solely for
17  *    personal benefit and not for any commercial purpose or for
18  *    monetary gain.
19  *
20  * THIS SOFTWARE IS PROVIDED BY BLUEKITCHEN GMBH AND CONTRIBUTORS
21  * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
22  * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
23  * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL BLUEKITCHEN
24  * GMBH OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
25  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
26  * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
27  * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
28  * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
29  * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF
30  * THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
31  * SUCH DAMAGE.
32  *
33  * Please inquire about commercial licensing options at
34  * [email protected]
35  *
36  */
37 
38 #define BTSTACK_FILE__ "gatt_client.c"
39 
40 #include <stdint.h>
41 #include <string.h>
42 #include <stddef.h>
43 
44 #include "btstack_config.h"
45 
46 #include "ble/att_dispatch.h"
47 #include "ble/att_db.h"
48 #include "ble/gatt_client.h"
49 #include "ble/le_device_db.h"
50 #include "ble/sm.h"
51 #include "bluetooth_psm.h"
52 #include "btstack_debug.h"
53 #include "btstack_event.h"
54 #include "btstack_memory.h"
55 #include "btstack_run_loop.h"
56 #include "btstack_util.h"
57 #include "hci.h"
58 #include "hci_dump.h"
59 #include "hci_event_builder.h"
60 #include "l2cap.h"
61 #include "classic/sdp_client.h"
62 #include "bluetooth_gatt.h"
63 #include "bluetooth_sdp.h"
64 #include "classic/sdp_util.h"
65 
66 #if defined(ENABLE_GATT_OVER_EATT) && !defined(ENABLE_L2CAP_ENHANCED_CREDIT_BASED_FLOW_CONTROL_MODE)
67 #error "GATT Over EATT requires support for L2CAP Enhanced CoC. Please enable ENABLE_L2CAP_ENHANCED_CREDIT_BASED_FLOW_CONTROL_MODE"
68 #endif
69 
70 // L2CAP Test Spec p35 defines a minimum of 100 ms, but PTS might indicate an error if we sent after 100 ms
71 #define GATT_CLIENT_COLLISION_BACKOFF_MS 150
72 
73 static btstack_linked_list_t gatt_client_connections;
74 static btstack_linked_list_t gatt_client_value_listeners;
75 #ifdef ENABLE_GATT_CLIENT_SERVICE_CHANGED
76 static btstack_linked_list_t gatt_client_service_changed_handler;
77 #endif
78 static btstack_packet_callback_registration_t hci_event_callback_registration;
79 static btstack_packet_callback_registration_t sm_event_callback_registration;
80 static btstack_context_callback_registration_t gatt_client_deferred_event_emit;
81 
82 // GATT Client Configuration
83 static bool                 gatt_client_mtu_exchange_enabled;
84 static gap_security_level_t gatt_client_required_security_level;
85 
86 static void gatt_client_att_packet_handler(uint8_t packet_type, uint16_t handle, uint8_t *packet, uint16_t size);
87 static void gatt_client_event_packet_handler(uint8_t packet_type, uint16_t channel, uint8_t *packet, uint16_t size);
88 static void gatt_client_report_error_if_pending(gatt_client_t *gatt_client, uint8_t att_error_code);
89 
90 #ifdef ENABLE_LE_SIGNED_WRITE
91 static void att_signed_write_handle_cmac_result(uint8_t hash[8]);
92 #endif
93 
94 #ifdef ENABLE_GATT_OVER_CLASSIC
95 static gatt_client_t * gatt_client_get_context_for_l2cap_cid(uint16_t l2cap_cid);
96 static void gatt_client_classic_handle_connected(gatt_client_t * gatt_client, uint8_t status);
97 static void gatt_client_classic_handle_disconnected(gatt_client_t * gatt_client);
98 static void gatt_client_classic_retry(btstack_timer_source_t * ts);
99 #endif
100 
101 #ifdef ENABLE_GATT_OVER_EATT
102 static bool gatt_client_le_enhanced_handle_can_send_query(gatt_client_t * gatt_client);
103 static void gatt_client_le_enhanced_retry(btstack_timer_source_t * ts);
104 #endif
105 
106 void gatt_client_init(void){
107     gatt_client_connections = NULL;
108 #ifdef ENABLE_GATT_CLIENT_SERVICE_CHANGED
109     gatt_client_service_changed_handler = NULL;
110 #endif
111     // default configuration
112     gatt_client_mtu_exchange_enabled    = true;
113     gatt_client_required_security_level = LEVEL_0;
114 
115     // register for HCI Events
116     hci_event_callback_registration.callback = &gatt_client_event_packet_handler;
117     hci_add_event_handler(&hci_event_callback_registration);
118 
119     // register for SM Events
120     sm_event_callback_registration.callback = &gatt_client_event_packet_handler;
121     sm_add_event_handler(&sm_event_callback_registration);
122 
123     // and ATT Client PDUs
124     att_dispatch_register_client(gatt_client_att_packet_handler);
125 }
126 
127 void gatt_client_set_required_security_level(gap_security_level_t level){
128     gatt_client_required_security_level = level;
129 }
130 
131 static gatt_client_t * gatt_client_for_timer(btstack_timer_source_t * ts){
132     btstack_linked_list_iterator_t it;
133     btstack_linked_list_iterator_init(&it, &gatt_client_connections);
134     while (btstack_linked_list_iterator_has_next(&it)){
135         gatt_client_t * gatt_client = (gatt_client_t *) btstack_linked_list_iterator_next(&it);
136         if (&gatt_client->gc_timeout == ts) {
137             return gatt_client;
138         }
139     }
140     return NULL;
141 }
142 
143 static void gatt_client_timeout_handler(btstack_timer_source_t * timer){
144     gatt_client_t * gatt_client = gatt_client_for_timer(timer);
145     if (gatt_client == NULL) return;
146     log_info("GATT client timeout handle, handle 0x%02x", gatt_client->con_handle);
147     gatt_client_report_error_if_pending(gatt_client, ATT_ERROR_TIMEOUT);
148 }
149 
150 static void gatt_client_timeout_start(gatt_client_t * gatt_client){
151     log_debug("GATT client timeout start, handle 0x%02x", gatt_client->con_handle);
152     btstack_run_loop_remove_timer(&gatt_client->gc_timeout);
153     btstack_run_loop_set_timer_handler(&gatt_client->gc_timeout, gatt_client_timeout_handler);
154     btstack_run_loop_set_timer(&gatt_client->gc_timeout, 30000); // 30 seconds sm timeout
155     btstack_run_loop_add_timer(&gatt_client->gc_timeout);
156 }
157 
158 static void gatt_client_timeout_stop(gatt_client_t * gatt_client){
159     log_debug("GATT client timeout stop, handle 0x%02x", gatt_client->con_handle);
160     btstack_run_loop_remove_timer(&gatt_client->gc_timeout);
161 }
162 
163 static gap_security_level_t gatt_client_le_security_level_for_connection(hci_con_handle_t con_handle){
164     uint8_t encryption_key_size = gap_encryption_key_size(con_handle);
165     if (encryption_key_size == 0) return LEVEL_0;
166 
167     bool authenticated = gap_authenticated(con_handle);
168     if (!authenticated) return LEVEL_2;
169 
170     return encryption_key_size == 16 ? LEVEL_4 : LEVEL_3;
171 }
172 
173 static gatt_client_t * gatt_client_get_context_for_handle(uint16_t handle){
174     btstack_linked_item_t *it;
175     for (it = (btstack_linked_item_t *) gatt_client_connections; it != NULL; it = it->next){
176         gatt_client_t * gatt_client = (gatt_client_t *) it;
177         if (gatt_client->con_handle == handle){
178             return gatt_client;
179         }
180     }
181     return NULL;
182 }
183 
184 
185 // @return gatt_client context
186 // returns existing one, or tries to setup new one
187 static uint8_t gatt_client_provide_context_for_handle(hci_con_handle_t con_handle, gatt_client_t ** out_gatt_client){
188     gatt_client_t * gatt_client = gatt_client_get_context_for_handle(con_handle);
189 
190     if (gatt_client != NULL){
191         *out_gatt_client = gatt_client;
192         return ERROR_CODE_SUCCESS;
193     }
194 
195     // bail if no such hci connection
196     hci_connection_t * hci_connection = hci_connection_for_handle(con_handle);
197     if (hci_connection == NULL){
198         log_error("No connection for handle 0x%04x", con_handle);
199         *out_gatt_client = NULL;
200         return ERROR_CODE_UNKNOWN_CONNECTION_IDENTIFIER;
201     }
202 
203     gatt_client = btstack_memory_gatt_client_get();
204     if (gatt_client == NULL){
205         *out_gatt_client = NULL;
206         return ERROR_CODE_MEMORY_CAPACITY_EXCEEDED;
207     }
208     // init state
209     gatt_client->bearer_type = ATT_BEARER_UNENHANCED_LE;
210     gatt_client->con_handle = con_handle;
211     gatt_client->mtu = ATT_DEFAULT_MTU;
212     gatt_client->security_level = gatt_client_le_security_level_for_connection(con_handle);
213     if (gatt_client_mtu_exchange_enabled){
214         gatt_client->mtu_state = SEND_MTU_EXCHANGE;
215     } else {
216         gatt_client->mtu_state = MTU_AUTO_EXCHANGE_DISABLED;
217     }
218     gatt_client->state = P_READY;
219     gatt_client->gatt_service_state = GATT_CLIENT_SERVICE_DISCOVER_W2_SEND;
220 #ifdef ENABLE_GATT_OVER_EATT
221     gatt_client->eatt_state = GATT_CLIENT_EATT_IDLE;
222 #endif
223     btstack_linked_list_add(&gatt_client_connections, (btstack_linked_item_t*)gatt_client);
224 
225     // get unenhanced att bearer state
226     if (hci_connection->att_connection.mtu_exchanged){
227         gatt_client->mtu = hci_connection->att_connection.mtu;
228         gatt_client->mtu_state = MTU_EXCHANGED;
229     }
230     *out_gatt_client = gatt_client;
231     return ERROR_CODE_SUCCESS;
232 }
233 
234 static bool is_ready(gatt_client_t * gatt_client){
235     return gatt_client->state == P_READY;
236 }
237 
238 static uint8_t gatt_client_provide_context_for_request(hci_con_handle_t con_handle, gatt_client_t ** out_gatt_client){
239     gatt_client_t * gatt_client = NULL;
240     uint8_t status = gatt_client_provide_context_for_handle(con_handle, &gatt_client);
241     if (status != ERROR_CODE_SUCCESS){
242         return status;
243     }
244 
245 #ifdef ENABLE_GATT_OVER_EATT
246     if (gatt_client->eatt_state == GATT_CLIENT_EATT_READY){
247         btstack_linked_list_iterator_t it;
248         gatt_client_t * eatt_client = NULL;
249         // find free eatt client
250         btstack_linked_list_iterator_init(&it, &gatt_client->eatt_clients);
251         while (btstack_linked_list_iterator_has_next(&it)){
252             gatt_client_t * client = (gatt_client_t *) btstack_linked_list_iterator_next(&it);
253             if (client->state == P_READY){
254                 eatt_client = client;
255                 break;
256             }
257         }
258         if (eatt_client == NULL){
259             return ERROR_CODE_COMMAND_DISALLOWED;
260         }
261         gatt_client = eatt_client;
262     }
263 #endif
264 
265     if (is_ready(gatt_client) == false){
266         return GATT_CLIENT_IN_WRONG_STATE;
267     }
268 
269     gatt_client_timeout_start(gatt_client);
270 
271     *out_gatt_client = gatt_client;
272 
273     return status;
274 }
275 
276 int gatt_client_is_ready(hci_con_handle_t con_handle){
277     gatt_client_t * gatt_client;
278     uint8_t status = gatt_client_provide_context_for_handle(con_handle, &gatt_client);
279     if (status != ERROR_CODE_SUCCESS){
280         return 0;
281     }
282     return is_ready(gatt_client) ? 1 : 0;
283 }
284 
285 void gatt_client_mtu_enable_auto_negotiation(uint8_t enabled){
286     gatt_client_mtu_exchange_enabled = enabled != 0;
287 }
288 
289 uint8_t gatt_client_get_mtu(hci_con_handle_t con_handle, uint16_t * mtu){
290     gatt_client_t * gatt_client;
291     uint8_t status = gatt_client_provide_context_for_handle(con_handle, &gatt_client);
292     if (status != ERROR_CODE_SUCCESS){
293         return status;
294     }
295 
296     if ((gatt_client->mtu_state == MTU_EXCHANGED) || (gatt_client->mtu_state == MTU_AUTO_EXCHANGE_DISABLED)){
297         *mtu = gatt_client->mtu;
298         return ERROR_CODE_SUCCESS;
299     }
300     *mtu = ATT_DEFAULT_MTU;
301     return GATT_CLIENT_IN_WRONG_STATE;
302 }
303 
304 static uint8_t *gatt_client_reserve_request_buffer(gatt_client_t *gatt_client) {
305     switch (gatt_client->bearer_type){
306 #ifdef ENABLE_GATT_OVER_CLASSIC
307         case ATT_BEARER_UNENHANCED_CLASSIC:
308 #endif
309         case ATT_BEARER_UNENHANCED_LE:
310             l2cap_reserve_packet_buffer();
311             return l2cap_get_outgoing_buffer();
312 #ifdef ENABLE_GATT_OVER_EATT
313         case ATT_BEARER_ENHANCED_LE:
314             return gatt_client->eatt_storage_buffer;
315 #endif
316         default:
317             btstack_unreachable();
318             break;
319     }
320     return NULL;
321 }
322 
323 // precondition: can_send_packet_now == TRUE
324 static uint8_t gatt_client_send(gatt_client_t * gatt_client, uint16_t len){
325     switch (gatt_client->bearer_type){
326         case ATT_BEARER_UNENHANCED_LE:
327             return l2cap_send_prepared_connectionless(gatt_client->con_handle, L2CAP_CID_ATTRIBUTE_PROTOCOL, len);
328 #ifdef ENABLE_GATT_OVER_CLASSIC
329         case ATT_BEARER_UNENHANCED_CLASSIC:
330             return l2cap_send_prepared(gatt_client->l2cap_cid, len);
331 #endif
332 #ifdef ENABLE_GATT_OVER_EATT
333         case ATT_BEARER_ENHANCED_LE:
334             return l2cap_send(gatt_client->l2cap_cid, gatt_client->eatt_storage_buffer, len);
335 #endif
336         default:
337             btstack_unreachable();
338             return ERROR_CODE_HARDWARE_FAILURE;
339     }
340 }
341 
342 // precondition: can_send_packet_now == TRUE
343 static uint8_t att_confirmation(gatt_client_t * gatt_client) {
344     uint8_t *request = gatt_client_reserve_request_buffer(gatt_client);
345 
346     request[0] = ATT_HANDLE_VALUE_CONFIRMATION;
347 
348     return gatt_client_send(gatt_client, 1);
349 }
350 
351 // precondition: can_send_packet_now == TRUE
352 static uint8_t att_find_information_request(gatt_client_t *gatt_client, uint8_t request_type, uint16_t start_handle,
353                                             uint16_t end_handle) {
354     uint8_t *request = gatt_client_reserve_request_buffer(gatt_client);
355 
356     request[0] = request_type;
357     little_endian_store_16(request, 1, start_handle);
358     little_endian_store_16(request, 3, end_handle);
359 
360     return gatt_client_send(gatt_client, 5);
361 }
362 
363 // precondition: can_send_packet_now == TRUE
364 static uint8_t
365 att_find_by_type_value_request(gatt_client_t *gatt_client, uint8_t request_type, uint16_t attribute_group_type,
366                                uint16_t start_handle, uint16_t end_handle, uint8_t *value, uint16_t value_size) {
367     uint8_t *request = gatt_client_reserve_request_buffer(gatt_client);
368     request[0] = request_type;
369 
370     little_endian_store_16(request, 1, start_handle);
371     little_endian_store_16(request, 3, end_handle);
372     little_endian_store_16(request, 5, attribute_group_type);
373     (void)memcpy(&request[7], value, value_size);
374 
375     return gatt_client_send(gatt_client, 7u + value_size);
376 }
377 
378 // precondition: can_send_packet_now == TRUE
379 static uint8_t
380 att_read_by_type_or_group_request_for_uuid16(gatt_client_t *gatt_client, uint8_t request_type, uint16_t uuid16,
381                                              uint16_t start_handle, uint16_t end_handle) {
382     uint8_t *request = gatt_client_reserve_request_buffer(gatt_client);
383 
384     request[0] = request_type;
385     little_endian_store_16(request, 1, start_handle);
386     little_endian_store_16(request, 3, end_handle);
387     little_endian_store_16(request, 5, uuid16);
388 
389     return gatt_client_send(gatt_client, 7);
390 }
391 
392 // precondition: can_send_packet_now == TRUE
393 static uint8_t
394 att_read_by_type_or_group_request_for_uuid128(gatt_client_t *gatt_client, uint8_t request_type, const uint8_t *uuid128,
395                                               uint16_t start_handle, uint16_t end_handle) {
396     uint8_t *request = gatt_client_reserve_request_buffer(gatt_client);
397 
398     request[0] = request_type;
399     little_endian_store_16(request, 1, start_handle);
400     little_endian_store_16(request, 3, end_handle);
401     reverse_128(uuid128, &request[5]);
402 
403     return gatt_client_send(gatt_client, 21);
404 }
405 
406 // precondition: can_send_packet_now == TRUE
407 static uint8_t att_read_request(gatt_client_t *gatt_client, uint8_t request_type, uint16_t attribute_handle) {
408     uint8_t *request = gatt_client_reserve_request_buffer(gatt_client);
409 
410     request[0] = request_type;
411     little_endian_store_16(request, 1, attribute_handle);
412 
413     return gatt_client_send(gatt_client, 3);
414 }
415 
416 // precondition: can_send_packet_now == TRUE
417 static uint8_t att_read_blob_request(gatt_client_t *gatt_client, uint8_t request_type, uint16_t attribute_handle,
418                                      uint16_t value_offset) {
419     uint8_t *request = gatt_client_reserve_request_buffer(gatt_client);
420 
421     request[0] = request_type;
422     little_endian_store_16(request, 1, attribute_handle);
423     little_endian_store_16(request, 3, value_offset);
424 
425     return gatt_client_send(gatt_client, 5);
426 }
427 
428 static uint8_t
429 att_read_multiple_request_with_opcode(gatt_client_t *gatt_client, uint16_t num_value_handles, uint16_t *value_handles, uint8_t opcode) {
430     uint8_t *request = gatt_client_reserve_request_buffer(gatt_client);
431 
432     request[0] = opcode;
433     uint16_t i;
434     uint16_t offset = 1;
435     for (i=0;i<num_value_handles;i++){
436         little_endian_store_16(request, offset, value_handles[i]);
437         offset += 2;
438     }
439 
440     return gatt_client_send(gatt_client, offset);
441 }
442 
443 static uint8_t
444 att_read_multiple_request(gatt_client_t *gatt_client, uint16_t num_value_handles, uint16_t *value_handles) {
445     return att_read_multiple_request_with_opcode(gatt_client, num_value_handles, value_handles, ATT_READ_MULTIPLE_REQUEST);
446 }
447 
448 #ifdef ENABLE_GATT_OVER_EATT
449 static uint8_t
450 att_read_multiple_variable_request(gatt_client_t *gatt_client, uint16_t num_value_handles, uint16_t *value_handles) {
451     return att_read_multiple_request_with_opcode(gatt_client, num_value_handles, value_handles, ATT_READ_MULTIPLE_VARIABLE_REQ);
452 }
453 #endif
454 
455 #ifdef ENABLE_LE_SIGNED_WRITE
456 // precondition: can_send_packet_now == TRUE
457 static uint8_t att_signed_write_request(gatt_client_t *gatt_client, uint16_t request_type, uint16_t attribute_handle,
458                                         uint16_t value_length, uint8_t *value, uint32_t sign_counter, uint8_t sgn[8]) {
459     uint8_t *request = gatt_client_reserve_request_buffer(gatt_client);
460 
461     request[0] = request_type;
462     little_endian_store_16(request, 1, attribute_handle);
463     (void)memcpy(&request[3], value, value_length);
464     little_endian_store_32(request, 3 + value_length, sign_counter);
465     reverse_64(sgn, &request[3 + value_length + 4]);
466 
467     return gatt_client_send(gatt_client, 3 + value_length + 12);
468 }
469 #endif
470 
471 // precondition: can_send_packet_now == TRUE
472 static uint8_t
473 att_write_request(gatt_client_t *gatt_client, uint8_t request_type, uint16_t attribute_handle, uint16_t value_length,
474                   uint8_t *value) {
475     uint8_t *request = gatt_client_reserve_request_buffer(gatt_client);
476 
477     request[0] = request_type;
478     little_endian_store_16(request, 1, attribute_handle);
479     (void)memcpy(&request[3], value, value_length);
480 
481     return gatt_client_send(gatt_client, 3u + value_length);
482 }
483 
484 // precondition: can_send_packet_now == TRUE
485 static uint8_t att_execute_write_request(gatt_client_t *gatt_client, uint8_t request_type, uint8_t execute_write) {
486     uint8_t *request = gatt_client_reserve_request_buffer(gatt_client);
487 
488     request[0] = request_type;
489     request[1] = execute_write;
490 
491     return gatt_client_send(gatt_client, 2);
492 }
493 
494 // precondition: can_send_packet_now == TRUE
495 static uint8_t att_prepare_write_request(gatt_client_t *gatt_client, uint8_t request_type, uint16_t attribute_handle,
496                                          uint16_t value_offset, uint16_t blob_length, uint8_t *value) {
497     uint8_t *request = gatt_client_reserve_request_buffer(gatt_client);
498 
499     request[0] = request_type;
500     little_endian_store_16(request, 1, attribute_handle);
501     little_endian_store_16(request, 3, value_offset);
502     (void)memcpy(&request[5], &value[value_offset], blob_length);
503 
504     return gatt_client_send(gatt_client,  5u + blob_length);
505 }
506 
507 static uint8_t att_exchange_mtu_request(gatt_client_t *gatt_client) {
508     uint8_t *request = gatt_client_reserve_request_buffer(gatt_client);
509 
510     request[0] = ATT_EXCHANGE_MTU_REQUEST;
511     uint16_t mtu = l2cap_max_le_mtu();
512     little_endian_store_16(request, 1, mtu);
513 
514     return gatt_client_send(gatt_client, 3);
515 }
516 
517 static uint16_t write_blob_length(gatt_client_t * gatt_client){
518     uint16_t max_blob_length = gatt_client->mtu - 5u;
519     if (gatt_client->attribute_offset >= gatt_client->attribute_length) {
520         return 0;
521     }
522     uint16_t rest_length = gatt_client->attribute_length - gatt_client->attribute_offset;
523     if (max_blob_length > rest_length){
524         return rest_length;
525     }
526     return max_blob_length;
527 }
528 
529 static void send_gatt_services_request(gatt_client_t *gatt_client){
530     att_read_by_type_or_group_request_for_uuid16(gatt_client, ATT_READ_BY_GROUP_TYPE_REQUEST,
531                                                  gatt_client->uuid16, gatt_client->start_group_handle,
532                                                  gatt_client->end_group_handle);
533 }
534 
535 static void send_gatt_by_uuid_request(gatt_client_t *gatt_client, uint16_t attribute_group_type){
536     if (gatt_client->uuid16 != 0u){
537         uint8_t uuid16[2];
538         little_endian_store_16(uuid16, 0, gatt_client->uuid16);
539         att_find_by_type_value_request(gatt_client, ATT_FIND_BY_TYPE_VALUE_REQUEST, attribute_group_type,
540                                        gatt_client->start_group_handle, gatt_client->end_group_handle, uuid16, 2);
541         return;
542     }
543     uint8_t uuid128[16];
544     reverse_128(gatt_client->uuid128, uuid128);
545     att_find_by_type_value_request(gatt_client, ATT_FIND_BY_TYPE_VALUE_REQUEST, attribute_group_type,
546                                    gatt_client->start_group_handle, gatt_client->end_group_handle, uuid128, 16);
547 }
548 
549 static void send_gatt_services_by_uuid_request(gatt_client_t *gatt_client){
550     send_gatt_by_uuid_request(gatt_client, GATT_PRIMARY_SERVICE_UUID);
551 }
552 
553 static void send_gatt_included_service_uuid_request(gatt_client_t *gatt_client){
554     att_read_request(gatt_client, ATT_READ_REQUEST, gatt_client->query_start_handle);
555 }
556 
557 static void send_gatt_included_service_request(gatt_client_t *gatt_client){
558     att_read_by_type_or_group_request_for_uuid16(gatt_client, ATT_READ_BY_TYPE_REQUEST,
559                                                  GATT_INCLUDE_SERVICE_UUID, gatt_client->start_group_handle,
560                                                  gatt_client->end_group_handle);
561 }
562 
563 static void send_gatt_characteristic_request(gatt_client_t *gatt_client){
564     att_read_by_type_or_group_request_for_uuid16(gatt_client, ATT_READ_BY_TYPE_REQUEST,
565                                                  GATT_CHARACTERISTICS_UUID, gatt_client->start_group_handle,
566                                                  gatt_client->end_group_handle);
567 }
568 
569 static void send_gatt_characteristic_descriptor_request(gatt_client_t *gatt_client){
570     att_find_information_request(gatt_client, ATT_FIND_INFORMATION_REQUEST, gatt_client->start_group_handle,
571                                  gatt_client->end_group_handle);
572 }
573 
574 static void send_gatt_read_characteristic_value_request(gatt_client_t *gatt_client){
575     att_read_request(gatt_client, ATT_READ_REQUEST, gatt_client->attribute_handle);
576 }
577 
578 static void send_gatt_read_by_type_request(gatt_client_t * gatt_client){
579     if (gatt_client->uuid16 != 0u){
580         att_read_by_type_or_group_request_for_uuid16(gatt_client, ATT_READ_BY_TYPE_REQUEST,
581                                                      gatt_client->uuid16, gatt_client->start_group_handle,
582                                                      gatt_client->end_group_handle);
583     } else {
584         att_read_by_type_or_group_request_for_uuid128(gatt_client, ATT_READ_BY_TYPE_REQUEST,
585                                                       gatt_client->uuid128, gatt_client->start_group_handle,
586                                                       gatt_client->end_group_handle);
587     }
588 }
589 
590 static void send_gatt_read_blob_request(gatt_client_t *gatt_client){
591     if (gatt_client->attribute_offset == 0){
592         att_read_request(gatt_client, ATT_READ_REQUEST, gatt_client->attribute_handle);
593     } else {
594         att_read_blob_request(gatt_client, ATT_READ_BLOB_REQUEST, gatt_client->attribute_handle,
595                               gatt_client->attribute_offset);
596     }
597 }
598 
599 static void send_gatt_read_multiple_request(gatt_client_t * gatt_client){
600     att_read_multiple_request(gatt_client, gatt_client->read_multiple_handle_count, gatt_client->read_multiple_handles);
601 }
602 
603 #ifdef ENABLE_GATT_OVER_EATT
604 static void send_gatt_read_multiple_variable_request(gatt_client_t * gatt_client){
605     att_read_multiple_variable_request(gatt_client, gatt_client->read_multiple_handle_count, gatt_client->read_multiple_handles);
606 }
607 #endif
608 
609 static void send_gatt_write_attribute_value_request(gatt_client_t * gatt_client){
610     att_write_request(gatt_client, ATT_WRITE_REQUEST, gatt_client->attribute_handle, gatt_client->attribute_length,
611                       gatt_client->attribute_value);
612 }
613 
614 static void send_gatt_write_client_characteristic_configuration_request(gatt_client_t * gatt_client){
615     att_write_request(gatt_client, ATT_WRITE_REQUEST, gatt_client->client_characteristic_configuration_handle, 2,
616                       gatt_client->client_characteristic_configuration_value);
617 }
618 
619 static void send_gatt_prepare_write_request(gatt_client_t * gatt_client){
620     att_prepare_write_request(gatt_client, ATT_PREPARE_WRITE_REQUEST, gatt_client->attribute_handle,
621                               gatt_client->attribute_offset, write_blob_length(gatt_client),
622                               gatt_client->attribute_value);
623 }
624 
625 static void send_gatt_execute_write_request(gatt_client_t * gatt_client){
626     att_execute_write_request(gatt_client, ATT_EXECUTE_WRITE_REQUEST, 1);
627 }
628 
629 static void send_gatt_cancel_prepared_write_request(gatt_client_t * gatt_client){
630     att_execute_write_request(gatt_client, ATT_EXECUTE_WRITE_REQUEST, 0);
631 }
632 
633 #ifndef ENABLE_GATT_FIND_INFORMATION_FOR_CCC_DISCOVERY
634 static void send_gatt_read_client_characteristic_configuration_request(gatt_client_t * gatt_client){
635     att_read_by_type_or_group_request_for_uuid16(gatt_client, ATT_READ_BY_TYPE_REQUEST,
636                                                  GATT_CLIENT_CHARACTERISTICS_CONFIGURATION,
637                                                  gatt_client->start_group_handle, gatt_client->end_group_handle);
638 }
639 #endif
640 
641 static void send_gatt_read_characteristic_descriptor_request(gatt_client_t * gatt_client){
642     att_read_request(gatt_client, ATT_READ_REQUEST, gatt_client->attribute_handle);
643 }
644 
645 #ifdef ENABLE_LE_SIGNED_WRITE
646 static void send_gatt_signed_write_request(gatt_client_t * gatt_client, uint32_t sign_counter){
647     att_signed_write_request(gatt_client, ATT_SIGNED_WRITE_COMMAND, gatt_client->attribute_handle,
648                              gatt_client->attribute_length, gatt_client->attribute_value, sign_counter,
649                              gatt_client->cmac);
650 }
651 #endif
652 
653 static uint16_t get_last_result_handle_from_service_list(uint8_t * packet, uint16_t size){
654     if (size < 2) return 0xffff;
655     uint8_t attr_length = packet[1];
656     if ((2 + attr_length) > size) return 0xffff;
657     return little_endian_read_16(packet, size - attr_length + 2u);
658 }
659 
660 static uint16_t get_last_result_handle_from_characteristics_list(uint8_t * packet, uint16_t size){
661     if (size < 2) return 0xffff;
662     uint8_t attr_length = packet[1];
663     if ((2 + attr_length) > size) return 0xffff;
664     return little_endian_read_16(packet, size - attr_length + 3u);
665 }
666 
667 static uint16_t get_last_result_handle_from_included_services_list(uint8_t * packet, uint16_t size){
668     if (size < 2) return 0xffff;
669     uint8_t attr_length = packet[1];
670     if ((2 + attr_length) > size) return 0xffff;
671     return little_endian_read_16(packet, size - attr_length);
672 }
673 
674 #ifdef ENABLE_GATT_CLIENT_SERVICE_CHANGED
675 static void gatt_client_service_emit_event(gatt_client_t * gatt_client, uint8_t * event, uint16_t size){
676     btstack_linked_list_iterator_t it;
677     btstack_linked_list_iterator_init(&it, &gatt_client_service_changed_handler);
678     while (btstack_linked_list_iterator_has_next(&it)) {
679         btstack_packet_callback_registration_t *callback = (btstack_packet_callback_registration_t *) btstack_linked_list_iterator_next(&it);
680         (*callback->callback)(HCI_EVENT_PACKET, (uint16_t) gatt_client->con_handle, event, size);
681     }
682 }
683 
684 static void
685 gatt_client_service_emit_database_hash(gatt_client_t *gatt_client, const uint8_t *value, uint16_t value_len) {
686     if (value_len == 16){
687         uint8_t event[21];
688         hci_event_builder_context_t context;
689         hci_event_builder_init(&context, event, sizeof(event), HCI_EVENT_GATTSERVICE_META, GATTSERVICE_SUBEVENT_GATT_DATABASE_HASH);
690         hci_event_builder_add_con_handle(&context, gatt_client->con_handle);
691         hci_event_builder_add_bytes(&context, value, 16);
692         gatt_client_service_emit_event(gatt_client, event, hci_event_builder_get_length(&context));
693     }
694 }
695 
696 static void
697 gatt_client_service_emit_service_changed(gatt_client_t *gatt_client, const uint8_t *value, uint16_t value_len) {
698     if (value_len == 4){
699         uint8_t event[9];
700         hci_event_builder_context_t context;
701         hci_event_builder_init(&context, event, sizeof(event), HCI_EVENT_GATTSERVICE_META, GATTSERVICE_SUBEVENT_GATT_SERVICE_CHANGED);
702         hci_event_builder_add_con_handle(&context, gatt_client->con_handle);
703         hci_event_builder_add_bytes(&context, value, 4);
704         gatt_client_service_emit_event(gatt_client, event, hci_event_builder_get_length(&context));
705     }
706 }
707 
708 static void gatt_client_service_packet_handler(uint8_t packet_type, uint16_t channel, uint8_t *packet, uint16_t size){
709     UNUSED(channel);  // ok: handling own l2cap events
710     UNUSED(size);     // ok: there is no channel
711 
712     hci_con_handle_t con_handle;
713     gatt_client_t *gatt_client;
714     gatt_client_service_t service;
715     gatt_client_characteristic_t characteristic;
716     switch (packet_type) {
717         case HCI_EVENT_PACKET:
718             switch (hci_event_packet_get_type(packet)) {
719                 case GATT_EVENT_SERVICE_QUERY_RESULT:
720                     con_handle = gatt_event_service_query_result_get_handle(packet);
721                     gatt_client = gatt_client_get_context_for_handle(con_handle);
722                     btstack_assert(gatt_client != NULL);
723                     btstack_assert(gatt_client->gatt_service_state == GATT_CLIENT_SERVICE_DISCOVER_W4_DONE);
724                     gatt_event_service_query_result_get_service(packet, &service);
725                     gatt_client->gatt_service_start_group_handle = service.start_group_handle;
726                     gatt_client->gatt_service_end_group_handle = service.end_group_handle;
727                     break;
728                 case GATT_EVENT_CHARACTERISTIC_QUERY_RESULT:
729                     con_handle = gatt_event_characteristic_query_result_get_handle(packet);
730                     gatt_client = gatt_client_get_context_for_handle(con_handle);
731                     btstack_assert(gatt_client != NULL);
732                     btstack_assert(gatt_client->gatt_service_state == GATT_CLIENT_SERVICE_DISCOVER_CHARACTERISTICS_W4_DONE);
733                     gatt_event_characteristic_query_result_get_characteristic(packet, &characteristic);
734                     switch (characteristic.uuid16){
735                         case ORG_BLUETOOTH_CHARACTERISTIC_GATT_SERVICE_CHANGED:
736                             gatt_client->gatt_service_changed_value_handle = characteristic.value_handle;
737                             gatt_client->gatt_service_changed_end_handle = characteristic.end_handle;
738                             break;
739                         case ORG_BLUETOOTH_CHARACTERISTIC_DATABASE_HASH:
740                             gatt_client->gatt_service_database_hash_value_handle = characteristic.value_handle;
741                             gatt_client->gatt_service_database_hash_end_handle = characteristic.end_handle;
742                             break;
743                         default:
744                             break;
745                     }
746                     break;
747                 case GATT_EVENT_CHARACTERISTIC_VALUE_QUERY_RESULT:
748                     con_handle = gatt_event_characteristic_value_query_result_get_handle(packet);
749                     gatt_client = gatt_client_get_context_for_handle(con_handle);
750                     btstack_assert(gatt_client != NULL);
751                     btstack_assert(gatt_client->gatt_service_state == GATT_CLIENT_SERVICE_DATABASE_HASH_READ_W4_DONE);
752                         gatt_client_service_emit_database_hash(gatt_client,
753                                                                gatt_event_characteristic_value_query_result_get_value(packet),
754                                                                gatt_event_characteristic_value_query_result_get_value_length(packet));
755                     break;
756                 case GATT_EVENT_QUERY_COMPLETE:
757                     con_handle = gatt_event_query_complete_get_handle(packet);
758                     gatt_client = gatt_client_get_context_for_handle(con_handle);
759                     btstack_assert(gatt_client != NULL);
760                     switch (gatt_client->gatt_service_state) {
761                         case GATT_CLIENT_SERVICE_DISCOVER_W4_DONE:
762                             gatt_client->gatt_service_state = GATT_CLIENT_SERVICE_DISCOVER_CHARACTERISTICS_W2_SEND;
763                             break;
764                         case GATT_CLIENT_SERVICE_DISCOVER_CHARACTERISTICS_W4_DONE:
765                             gatt_client->gatt_service_state = GATT_CLIENT_SERVICE_SERVICE_CHANGED_WRITE_CCCD_W2_SEND;
766                             break;
767                         case GATT_CLIENT_SERVICE_SERVICE_CHANGED_WRITE_CCCD_W4_DONE:
768                             gatt_client->gatt_service_state = GATT_CLIENT_SERVICE_DATABASE_HASH_READ_W2_SEND;
769                             break;
770                         case GATT_CLIENT_SERVICE_DATABASE_HASH_READ_W4_DONE:
771                             gatt_client->gatt_service_state = GATT_CLIENT_SERVICE_DATABASE_HASH_WRITE_CCCD_W2_SEND;
772                             break;
773                         case GATT_CLIENT_SERVICE_DATABASE_HASH_WRITE_CCCD_W4_DONE:
774                             gatt_client->gatt_service_state = GATT_CLIENT_SERVICE_DONE;
775                             break;
776                         default:
777                             btstack_unreachable();
778                             break;
779                     }
780                     break;
781                 default:
782                     break;
783             }
784             break;
785         default:
786             break;
787     }
788 }
789 #endif
790 
791 static void gatt_client_notify_can_send_query(gatt_client_t * gatt_client){
792 
793 #ifdef ENABLE_GATT_OVER_EATT
794     // if eatt is ready, notify all clients that can send a query
795     if (gatt_client->eatt_state == GATT_CLIENT_EATT_READY){
796         btstack_linked_list_iterator_t it;
797         btstack_linked_list_iterator_init(&it, &gatt_client->eatt_clients);
798         while (btstack_linked_list_iterator_has_next(&it)){
799             gatt_client_t * client = (gatt_client_t *) btstack_linked_list_iterator_next(&it);
800             if (client->state == P_READY){
801                 // call callback
802                 btstack_context_callback_registration_t * callback = (btstack_context_callback_registration_t *) btstack_linked_list_pop(&gatt_client->query_requests);
803                 if (callback == NULL) {
804                     return;
805                 }
806                 (*callback->callback)(callback->context);
807             }
808         }
809         return;
810     }
811 #endif
812 
813     while (gatt_client->state == P_READY){
814         bool query_sent = false;
815         UNUSED(query_sent);
816 
817 #ifdef ENABLE_GATT_CLIENT_SERVICE_CHANGED
818         uint8_t status = ERROR_CODE_SUCCESS;
819         gatt_client_service_t gatt_service;
820         gatt_client_characteristic_t characteristic;
821         switch (gatt_client->gatt_service_state){
822             case GATT_CLIENT_SERVICE_DISCOVER_W2_SEND:
823                 gatt_client->gatt_service_state = GATT_CLIENT_SERVICE_DISCOVER_W4_DONE;
824                 status = gatt_client_discover_primary_services_by_uuid16(&gatt_client_service_packet_handler,
825                                                                                          gatt_client->con_handle,
826                                                                                          ORG_BLUETOOTH_SERVICE_GENERIC_ATTRIBUTE);
827                 query_sent = true;
828                 break;
829             case GATT_CLIENT_SERVICE_DISCOVER_CHARACTERISTICS_W2_SEND:
830                 if (gatt_client->gatt_service_start_group_handle != 0){
831                     gatt_client->gatt_service_state = GATT_CLIENT_SERVICE_DISCOVER_CHARACTERISTICS_W4_DONE;
832                     gatt_service.start_group_handle = gatt_client->gatt_service_start_group_handle;
833                     gatt_service.end_group_handle   = gatt_client->gatt_service_end_group_handle;
834                     status = gatt_client_discover_characteristics_for_service(&gatt_client_service_packet_handler, gatt_client->con_handle, &gatt_service);
835                     query_sent = true;
836                     break;
837                 }
838 
839                 /* fall through */
840 
841             case GATT_CLIENT_SERVICE_SERVICE_CHANGED_WRITE_CCCD_W2_SEND:
842                 if (gatt_client->gatt_service_changed_value_handle != 0){
843                     gatt_client->gatt_service_state = GATT_CLIENT_SERVICE_SERVICE_CHANGED_WRITE_CCCD_W4_DONE;
844                     characteristic.value_handle = gatt_client->gatt_service_changed_value_handle;
845                     characteristic.end_handle   = gatt_client->gatt_service_changed_end_handle;
846                     // we assume good case. We cannot do much otherwise
847                     characteristic.properties = ATT_PROPERTY_INDICATE;
848                     status = gatt_client_write_client_characteristic_configuration(&gatt_client_service_packet_handler,
849                                                                                    gatt_client->con_handle, &characteristic,
850                                                                                    GATT_CLIENT_CHARACTERISTICS_CONFIGURATION_INDICATION);
851                     query_sent = true;
852                     break;
853                 }
854 
855                 /* fall through */
856 
857             case GATT_CLIENT_SERVICE_DATABASE_HASH_READ_W2_SEND:
858                 if (gatt_client->gatt_service_database_hash_value_handle != 0){
859                     gatt_client->gatt_service_state = GATT_CLIENT_SERVICE_DATABASE_HASH_READ_W4_DONE;
860                     status = gatt_client_read_value_of_characteristics_by_uuid16(&gatt_client_service_packet_handler,
861                                                                                          gatt_client->con_handle,
862                                                                                          0x0001, 0xffff, ORG_BLUETOOTH_CHARACTERISTIC_DATABASE_HASH);
863                     query_sent = true;
864                     break;
865                 }
866 
867                 /* fall through */
868 
869             case GATT_CLIENT_SERVICE_DATABASE_HASH_WRITE_CCCD_W2_SEND:
870                 if (gatt_client->gatt_service_database_hash_value_handle != 0) {
871                     gatt_client->gatt_service_state = GATT_CLIENT_SERVICE_DATABASE_HASH_WRITE_CCCD_W4_DONE;
872                     characteristic.value_handle = gatt_client->gatt_service_database_hash_value_handle;
873                     characteristic.end_handle = gatt_client->gatt_service_database_hash_end_handle;
874                     // we assume good case. We cannot do much otherwise
875                     characteristic.properties = ATT_PROPERTY_INDICATE;
876                     status = gatt_client_write_client_characteristic_configuration(&gatt_client_service_packet_handler,
877                                                                                    gatt_client->con_handle,
878                                                                                    &characteristic,
879                                                                                    GATT_CLIENT_CHARACTERISTICS_CONFIGURATION_INDICATION);
880                     query_sent = true;
881                     break;
882                 }
883 
884                 // DONE
885                 gatt_client->gatt_service_state = GATT_CLIENT_SERVICE_DONE;
886                 break;
887             default:
888                 break;
889         }
890         btstack_assert(status == ERROR_CODE_SUCCESS);
891         UNUSED(status);
892         if (query_sent){
893             continue;
894         }
895 #endif
896 
897 #ifdef ENABLE_GATT_OVER_EATT
898         query_sent = gatt_client_le_enhanced_handle_can_send_query(gatt_client);
899         if (query_sent){
900             continue;
901         }
902 #endif
903         btstack_context_callback_registration_t * callback = (btstack_context_callback_registration_t *) btstack_linked_list_pop(&gatt_client->query_requests);
904         if (callback == NULL) {
905             return;
906         }
907         (*callback->callback)(callback->context);
908     }
909 }
910 
911 // test if notification/indication should be delivered to application (BLESA)
912 static bool gatt_client_accept_server_message(gatt_client_t *gatt_client) {
913     // ignore messages until re-encryption is complete
914     if (gap_reconnect_security_setup_active(gatt_client->con_handle)) return false;
915 
916 	// after that ignore if bonded but not encrypted
917 	return !gap_bonded(gatt_client->con_handle) || (gap_encryption_key_size(gatt_client->con_handle) > 0);
918 }
919 
920 static void emit_event_new(btstack_packet_handler_t callback, uint8_t * packet, uint16_t size){
921     if (!callback) return;
922     hci_dump_btstack_event(packet, size);
923     (*callback)(HCI_EVENT_PACKET, 0, packet, size);
924 }
925 
926 static void emit_event_to_registered_listeners(hci_con_handle_t con_handle, uint16_t attribute_handle, uint8_t * packet, uint16_t size){
927     btstack_linked_list_iterator_t it;
928     btstack_linked_list_iterator_init(&it, &gatt_client_value_listeners);
929     while (btstack_linked_list_iterator_has_next(&it)){
930         gatt_client_notification_t * notification = (gatt_client_notification_t*) btstack_linked_list_iterator_next(&it);
931         if ((notification->con_handle       != GATT_CLIENT_ANY_CONNECTION)   && (notification->con_handle       != con_handle)) continue;
932         if ((notification->attribute_handle != GATT_CLIENT_ANY_VALUE_HANDLE) && (notification->attribute_handle != attribute_handle)) continue;
933         (*notification->callback)(HCI_EVENT_PACKET, 0, packet, size);
934     }
935 }
936 
937 static void emit_gatt_complete_event(gatt_client_t * gatt_client, uint8_t att_status){
938     // @format H1
939     uint8_t packet[5];
940     packet[0] = GATT_EVENT_QUERY_COMPLETE;
941     packet[1] = 3;
942     little_endian_store_16(packet, 2, gatt_client->con_handle);
943     packet[4] = att_status;
944     emit_event_new(gatt_client->callback, packet, sizeof(packet));
945 }
946 
947 static void emit_gatt_service_query_result_event(gatt_client_t * gatt_client, uint16_t start_group_handle, uint16_t end_group_handle, const uint8_t * uuid128){
948     // @format HX
949     uint8_t packet[24];
950     packet[0] = GATT_EVENT_SERVICE_QUERY_RESULT;
951     packet[1] = sizeof(packet) - 2u;
952     little_endian_store_16(packet, 2, gatt_client->con_handle);
953     ///
954     little_endian_store_16(packet, 4, start_group_handle);
955     little_endian_store_16(packet, 6, end_group_handle);
956     reverse_128(uuid128, &packet[8]);
957     emit_event_new(gatt_client->callback, packet, sizeof(packet));
958 }
959 
960 static void emit_gatt_included_service_query_result_event(gatt_client_t * gatt_client, uint16_t include_handle, uint16_t start_group_handle, uint16_t end_group_handle, const uint8_t * uuid128){
961     // @format HX
962     uint8_t packet[26];
963     packet[0] = GATT_EVENT_INCLUDED_SERVICE_QUERY_RESULT;
964     packet[1] = sizeof(packet) - 2u;
965     little_endian_store_16(packet, 2, gatt_client->con_handle);
966     ///
967     little_endian_store_16(packet, 4, include_handle);
968     //
969     little_endian_store_16(packet, 6, start_group_handle);
970     little_endian_store_16(packet, 8, end_group_handle);
971     reverse_128(uuid128, &packet[10]);
972     emit_event_new(gatt_client->callback, packet, sizeof(packet));
973 }
974 
975 static void emit_gatt_characteristic_query_result_event(gatt_client_t * gatt_client, uint16_t start_handle, uint16_t value_handle, uint16_t end_handle,
976                                                         uint16_t properties, const uint8_t * uuid128){
977     // @format HY
978     uint8_t packet[28];
979     packet[0] = GATT_EVENT_CHARACTERISTIC_QUERY_RESULT;
980     packet[1] = sizeof(packet) - 2u;
981     little_endian_store_16(packet, 2, gatt_client->con_handle);
982     ///
983     little_endian_store_16(packet, 4,  start_handle);
984     little_endian_store_16(packet, 6,  value_handle);
985     little_endian_store_16(packet, 8,  end_handle);
986     little_endian_store_16(packet, 10, properties);
987     reverse_128(uuid128, &packet[12]);
988     emit_event_new(gatt_client->callback, packet, sizeof(packet));
989 }
990 
991 static void emit_gatt_all_characteristic_descriptors_result_event(
992         gatt_client_t * gatt_client, uint16_t descriptor_handle, const uint8_t * uuid128){
993     // @format HZ
994     uint8_t packet[22];
995     packet[0] = GATT_EVENT_ALL_CHARACTERISTIC_DESCRIPTORS_QUERY_RESULT;
996     packet[1] = sizeof(packet) - 2u;
997     little_endian_store_16(packet, 2, gatt_client->con_handle);
998     ///
999     little_endian_store_16(packet, 4,  descriptor_handle);
1000     reverse_128(uuid128, &packet[6]);
1001     emit_event_new(gatt_client->callback, packet, sizeof(packet));
1002 }
1003 
1004 static void emit_gatt_mtu_exchanged_result_event(gatt_client_t * gatt_client, uint16_t new_mtu){
1005     // @format H2
1006     uint8_t packet[6];
1007     packet[0] = GATT_EVENT_MTU;
1008     packet[1] = sizeof(packet) - 2u;
1009     little_endian_store_16(packet, 2, gatt_client->con_handle);
1010     little_endian_store_16(packet, 4, new_mtu);
1011     att_dispatch_client_mtu_exchanged(gatt_client->con_handle, new_mtu);
1012     emit_event_new(gatt_client->callback, packet, sizeof(packet));
1013 }
1014 
1015 // helper
1016 static void gatt_client_handle_transaction_complete(gatt_client_t *gatt_client, uint8_t att_status) {
1017     gatt_client->state = P_READY;
1018     gatt_client_timeout_stop(gatt_client);
1019     emit_gatt_complete_event(gatt_client, att_status);
1020     gatt_client_notify_can_send_query(gatt_client);
1021 }
1022 
1023 // @return packet pointer
1024 // @note assume that value is part of an l2cap buffer - overwrite HCI + L2CAP packet headers
1025 #define CHARACTERISTIC_VALUE_EVENT_HEADER_SIZE 8
1026 static uint8_t *
1027 setup_characteristic_value_packet(const gatt_client_t *gatt_client, uint8_t type, uint16_t attribute_handle,
1028                                   uint8_t *value, uint16_t length) {
1029 #ifdef FUZZING_BUILD_MODE_UNSAFE_FOR_PRODUCTION
1030     // copy value into test packet for testing
1031     static uint8_t packet[1000];
1032     memcpy(&packet[CHARACTERISTIC_VALUE_EVENT_HEADER_SIZE], value, length);
1033 #else
1034     // before the value inside the ATT PDU
1035     uint8_t * packet = value - CHARACTERISTIC_VALUE_EVENT_HEADER_SIZE;
1036 #endif
1037     packet[0] = type;
1038     packet[1] = CHARACTERISTIC_VALUE_EVENT_HEADER_SIZE - 2 + length;
1039     little_endian_store_16(packet, 2, gatt_client->con_handle);
1040     little_endian_store_16(packet, 4, attribute_handle);
1041     little_endian_store_16(packet, 6, length);
1042     return packet;
1043 }
1044 
1045 // @return packet pointer
1046 // @note assume that value is part of an l2cap buffer - overwrite parts of the HCI/L2CAP/ATT packet (4/4/3) bytes
1047 #define LONG_CHARACTERISTIC_VALUE_EVENT_HEADER_SIZE 10
1048 
1049 // L2CAP Header (4) + ACL Header (4) => 8 bytes
1050 #if !defined(HCI_INCOMING_PRE_BUFFER_SIZE) || ((HCI_INCOMING_PRE_BUFFER_SIZE < LONG_CHARACTERISTIC_VALUE_EVENT_HEADER_SIZE - 8))
1051 #error "Long Characteristic reads requires HCI_INCOMING_PRE_BUFFER_SIZE >= 2"
1052 #endif
1053 
1054 static uint8_t * setup_long_characteristic_value_packet(uint8_t type, hci_con_handle_t con_handle, uint16_t attribute_handle, uint16_t offset, uint8_t * value, uint16_t length){
1055 #ifdef FUZZING_BUILD_MODE_UNSAFE_FOR_PRODUCTION
1056     // avoid using pre ATT headers.
1057     // copy value into test packet for testing
1058     static uint8_t packet[1000];
1059     memcpy(&packet[LONG_CHARACTERISTIC_VALUE_EVENT_HEADER_SIZE], value, length);
1060 #else
1061     // before the value inside the ATT PDU
1062     uint8_t * packet = value - LONG_CHARACTERISTIC_VALUE_EVENT_HEADER_SIZE;
1063 #endif
1064     packet[0] = type;
1065     packet[1] = LONG_CHARACTERISTIC_VALUE_EVENT_HEADER_SIZE - 2 + length;
1066     little_endian_store_16(packet, 2, con_handle);
1067     little_endian_store_16(packet, 4, attribute_handle);
1068     little_endian_store_16(packet, 6, offset);
1069     little_endian_store_16(packet, 8, length);
1070     return packet;
1071 }
1072 
1073 #if (LONG_CHARACTERISTIC_VALUE_EVENT_HEADER_SIZE > CHARACTERISTIC_VALUE_EVENT_HEADER_SIZE)
1074 #define REPORT_PREBUFFER_HEADER LONG_CHARACTERISTIC_VALUE_EVENT_HEADER_SIZE
1075 #else
1076 #define REPORT_PREBUFFER_HEADER CHARACTERISTIC_VALUE_EVENT_HEADER_SIZE
1077 #endif
1078 
1079 ///
1080 static void report_gatt_services(gatt_client_t * gatt_client, uint8_t * packet, uint16_t size){
1081     if (size < 2) return;
1082     uint8_t attr_length = packet[1];
1083     uint8_t uuid_length = attr_length - 4u;
1084 
1085     int i;
1086     for (i = 2; (i+attr_length) <= size; i += attr_length){
1087         uint16_t start_group_handle = little_endian_read_16(packet,i);
1088         uint16_t end_group_handle   = little_endian_read_16(packet,i+2);
1089         uint8_t  uuid128[16];
1090         uint16_t uuid16 = 0;
1091 
1092         if (uuid_length == 2u){
1093             uuid16 = little_endian_read_16(packet, i+4);
1094             uuid_add_bluetooth_prefix((uint8_t*) &uuid128, uuid16);
1095         } else if (uuid_length == 16u) {
1096             reverse_128(&packet[i+4], uuid128);
1097         } else {
1098             return;
1099         }
1100         emit_gatt_service_query_result_event(gatt_client, start_group_handle, end_group_handle, uuid128);
1101     }
1102 }
1103 
1104 static void report_gatt_characteristic_start_found(gatt_client_t * gatt_client, uint16_t start_handle, uint8_t properties, uint16_t value_handle, uint8_t * uuid, uint16_t uuid_length){
1105     uint8_t uuid128[16];
1106     uint16_t uuid16 = 0;
1107     if (uuid_length == 2u){
1108         uuid16 = little_endian_read_16(uuid, 0);
1109         uuid_add_bluetooth_prefix((uint8_t*) uuid128, uuid16);
1110     } else if (uuid_length == 16u){
1111         reverse_128(uuid, uuid128);
1112     } else {
1113         return;
1114     }
1115 
1116     if (gatt_client->filter_with_uuid && (memcmp(gatt_client->uuid128, uuid128, 16) != 0)) return;
1117 
1118     gatt_client->characteristic_properties = properties;
1119     gatt_client->characteristic_start_handle = start_handle;
1120     gatt_client->attribute_handle = value_handle;
1121 
1122     if (gatt_client->filter_with_uuid) return;
1123 
1124     gatt_client->uuid16 = uuid16;
1125     (void)memcpy(gatt_client->uuid128, uuid128, 16);
1126 }
1127 
1128 static void report_gatt_characteristic_end_found(gatt_client_t * gatt_client, uint16_t end_handle){
1129     // TODO: stop searching if filter and uuid found
1130 
1131     if (!gatt_client->characteristic_start_handle) return;
1132 
1133     emit_gatt_characteristic_query_result_event(gatt_client, gatt_client->characteristic_start_handle, gatt_client->attribute_handle,
1134                                                 end_handle, gatt_client->characteristic_properties, gatt_client->uuid128);
1135 
1136     gatt_client->characteristic_start_handle = 0;
1137 }
1138 
1139 
1140 static void report_gatt_characteristics(gatt_client_t * gatt_client, uint8_t * packet, uint16_t size){
1141     if (size < 2u) return;
1142     uint8_t attr_length = packet[1];
1143     if ((attr_length != 7u) && (attr_length != 21u)) return;
1144     uint8_t uuid_length = attr_length - 5u;
1145     int i;
1146     for (i = 2u; (i + attr_length) <= size; i += attr_length){
1147         uint16_t start_handle = little_endian_read_16(packet, i);
1148         uint8_t  properties = packet[i+2];
1149         uint16_t value_handle = little_endian_read_16(packet, i+3);
1150         report_gatt_characteristic_end_found(gatt_client, start_handle - 1u);
1151         report_gatt_characteristic_start_found(gatt_client, start_handle, properties, value_handle, &packet[i + 5],
1152                                                uuid_length);
1153     }
1154 }
1155 
1156 static void report_gatt_included_service_uuid16(gatt_client_t * gatt_client, uint16_t include_handle, uint16_t uuid16){
1157     uint8_t normalized_uuid128[16];
1158     uuid_add_bluetooth_prefix(normalized_uuid128, uuid16);
1159     emit_gatt_included_service_query_result_event(gatt_client, include_handle, gatt_client->query_start_handle,
1160                                                   gatt_client->query_end_handle, normalized_uuid128);
1161 }
1162 
1163 static void report_gatt_included_service_uuid128(gatt_client_t * gatt_client, uint16_t include_handle, const uint8_t * uuid128){
1164     emit_gatt_included_service_query_result_event(gatt_client, include_handle, gatt_client->query_start_handle,
1165                                                   gatt_client->query_end_handle, uuid128);
1166 }
1167 
1168 // @note assume that value is part of an l2cap buffer - overwrite parts of the HCI/L2CAP/ATT packet (4/4/3) bytes
1169 static void report_gatt_notification(gatt_client_t *gatt_client, uint16_t value_handle, uint8_t *value, int length) {
1170 	if (!gatt_client_accept_server_message(gatt_client)) return;
1171     uint8_t * packet = setup_characteristic_value_packet(gatt_client, GATT_EVENT_NOTIFICATION, value_handle,
1172                                                          value, length);
1173     emit_event_to_registered_listeners(gatt_client->con_handle, value_handle, packet, CHARACTERISTIC_VALUE_EVENT_HEADER_SIZE + length);
1174 }
1175 
1176 // @note assume that value is part of an l2cap buffer - overwrite parts of the HCI/L2CAP/ATT packet (4/4/3) bytes
1177 static void report_gatt_indication(gatt_client_t *gatt_client, uint16_t value_handle, uint8_t *value, int length) {
1178 	if (!gatt_client_accept_server_message(gatt_client)) return;
1179 #ifdef ENABLE_GATT_CLIENT_SERVICE_CHANGED
1180     // Directly Handle GATT Service Changed and Database Hash indications
1181     if (value_handle == gatt_client->gatt_service_database_hash_value_handle){
1182         gatt_client_service_emit_database_hash(gatt_client, value, length);
1183     }
1184     if (value_handle == gatt_client->gatt_service_changed_value_handle){
1185         gatt_client_service_emit_service_changed(gatt_client, value, length);
1186     }
1187 #endif
1188     uint8_t * packet = setup_characteristic_value_packet(gatt_client, GATT_EVENT_INDICATION, value_handle,
1189                                                          value, length);
1190     emit_event_to_registered_listeners(gatt_client->con_handle, value_handle, packet, CHARACTERISTIC_VALUE_EVENT_HEADER_SIZE + length);
1191 }
1192 
1193 // @note assume that value is part of an l2cap buffer - overwrite parts of the HCI/L2CAP/ATT packet (4/4/3) bytes
1194 static void report_gatt_characteristic_value(gatt_client_t * gatt_client, uint16_t attribute_handle, uint8_t * value, uint16_t length){
1195     uint8_t * packet = setup_characteristic_value_packet(
1196             gatt_client, GATT_EVENT_CHARACTERISTIC_VALUE_QUERY_RESULT, attribute_handle, value, length);
1197     emit_event_new(gatt_client->callback, packet, CHARACTERISTIC_VALUE_EVENT_HEADER_SIZE + length);
1198 }
1199 
1200 // @note assume that value is part of an l2cap buffer - overwrite parts of the HCI/L2CAP/ATT packet (4/4/3) bytes
1201 static void report_gatt_long_characteristic_value_blob(gatt_client_t * gatt_client, uint16_t attribute_handle, uint8_t * blob, uint16_t blob_length, int value_offset){
1202     uint8_t * packet = setup_long_characteristic_value_packet(GATT_EVENT_LONG_CHARACTERISTIC_VALUE_QUERY_RESULT, gatt_client->con_handle, attribute_handle, value_offset, blob, blob_length);
1203     emit_event_new(gatt_client->callback, packet, blob_length + LONG_CHARACTERISTIC_VALUE_EVENT_HEADER_SIZE);
1204 }
1205 
1206 static void report_gatt_characteristic_descriptor(gatt_client_t * gatt_client, uint16_t descriptor_handle, uint8_t *value, uint16_t value_length, uint16_t value_offset){
1207     UNUSED(value_offset);
1208     uint8_t * packet = setup_characteristic_value_packet(gatt_client, GATT_EVENT_CHARACTERISTIC_DESCRIPTOR_QUERY_RESULT,
1209                                                          descriptor_handle, value,
1210                                                          value_length);
1211     emit_event_new(gatt_client->callback, packet, value_length + 8u);
1212 }
1213 
1214 static void report_gatt_long_characteristic_descriptor(gatt_client_t * gatt_client, uint16_t descriptor_handle, uint8_t *blob, uint16_t blob_length, uint16_t value_offset){
1215     uint8_t * packet = setup_long_characteristic_value_packet(GATT_EVENT_LONG_CHARACTERISTIC_DESCRIPTOR_QUERY_RESULT, gatt_client->con_handle, descriptor_handle, value_offset, blob, blob_length);
1216     emit_event_new(gatt_client->callback, packet, blob_length + LONG_CHARACTERISTIC_VALUE_EVENT_HEADER_SIZE);
1217 }
1218 
1219 static void report_gatt_all_characteristic_descriptors(gatt_client_t * gatt_client, uint8_t * packet, uint16_t size, uint16_t pair_size){
1220     int i;
1221     for (i = 0u; (i + pair_size) <= size; i += pair_size){
1222         uint16_t descriptor_handle = little_endian_read_16(packet,i);
1223         uint8_t uuid128[16];
1224         uint16_t uuid16 = 0;
1225         if (pair_size == 4u){
1226             uuid16 = little_endian_read_16(packet,i+2);
1227             uuid_add_bluetooth_prefix(uuid128, uuid16);
1228         } else {
1229             reverse_128(&packet[i+2], uuid128);
1230         }
1231         emit_gatt_all_characteristic_descriptors_result_event(gatt_client, descriptor_handle, uuid128);
1232     }
1233 
1234 }
1235 
1236 static bool is_query_done(gatt_client_t * gatt_client, uint16_t last_result_handle){
1237     return last_result_handle >= gatt_client->end_group_handle;
1238 }
1239 
1240 static void trigger_next_query(gatt_client_t * gatt_client, uint16_t last_result_handle, gatt_client_state_t next_query_state){
1241     if (is_query_done(gatt_client, last_result_handle)){
1242         gatt_client_handle_transaction_complete(gatt_client, ATT_ERROR_SUCCESS);
1243         return;
1244     }
1245     // next
1246     gatt_client->start_group_handle = last_result_handle + 1u;
1247     gatt_client->state = next_query_state;
1248 }
1249 
1250 static void trigger_next_included_service_query(gatt_client_t * gatt_client, uint16_t last_result_handle){
1251     trigger_next_query(gatt_client, last_result_handle, P_W2_SEND_INCLUDED_SERVICE_QUERY);
1252 }
1253 
1254 static void trigger_next_service_query(gatt_client_t * gatt_client, uint16_t last_result_handle){
1255     trigger_next_query(gatt_client, last_result_handle, P_W2_SEND_SERVICE_QUERY);
1256 }
1257 
1258 static void trigger_next_service_by_uuid_query(gatt_client_t * gatt_client, uint16_t last_result_handle){
1259     trigger_next_query(gatt_client, last_result_handle, P_W2_SEND_SERVICE_WITH_UUID_QUERY);
1260 }
1261 
1262 static void trigger_next_characteristic_query(gatt_client_t * gatt_client, uint16_t last_result_handle){
1263     if (is_query_done(gatt_client, last_result_handle)){
1264         // report last characteristic
1265         report_gatt_characteristic_end_found(gatt_client, gatt_client->end_group_handle);
1266     }
1267     trigger_next_query(gatt_client, last_result_handle, P_W2_SEND_ALL_CHARACTERISTICS_OF_SERVICE_QUERY);
1268 }
1269 
1270 static void trigger_next_characteristic_descriptor_query(gatt_client_t * gatt_client, uint16_t last_result_handle){
1271     trigger_next_query(gatt_client, last_result_handle, P_W2_SEND_ALL_CHARACTERISTIC_DESCRIPTORS_QUERY);
1272 }
1273 
1274 static void trigger_next_read_by_type_query(gatt_client_t * gatt_client, uint16_t last_result_handle){
1275     trigger_next_query(gatt_client, last_result_handle, P_W2_SEND_READ_BY_TYPE_REQUEST);
1276 }
1277 
1278 static void trigger_next_prepare_write_query(gatt_client_t * gatt_client, gatt_client_state_t next_query_state, gatt_client_state_t done_state){
1279     gatt_client->attribute_offset += write_blob_length(gatt_client);
1280     uint16_t next_blob_length =  write_blob_length(gatt_client);
1281 
1282     if (next_blob_length == 0u){
1283         gatt_client->state = done_state;
1284         return;
1285     }
1286     gatt_client->state = next_query_state;
1287 }
1288 
1289 static void trigger_next_blob_query(gatt_client_t * gatt_client, gatt_client_state_t next_query_state, uint16_t received_blob_length){
1290 
1291     uint16_t max_blob_length = gatt_client->mtu - 1u;
1292     if (received_blob_length < max_blob_length){
1293         gatt_client_handle_transaction_complete(gatt_client, ATT_ERROR_SUCCESS);
1294         return;
1295     }
1296 
1297     gatt_client->attribute_offset += received_blob_length;
1298     gatt_client->state = next_query_state;
1299 }
1300 
1301 void gatt_client_listen_for_characteristic_value_updates(gatt_client_notification_t * notification, btstack_packet_handler_t callback, hci_con_handle_t con_handle, gatt_client_characteristic_t * characteristic){
1302     notification->callback = callback;
1303     notification->con_handle = con_handle;
1304     if (characteristic == NULL){
1305         notification->attribute_handle = GATT_CLIENT_ANY_VALUE_HANDLE;
1306     } else {
1307         notification->attribute_handle = characteristic->value_handle;
1308     }
1309     btstack_linked_list_add(&gatt_client_value_listeners, (btstack_linked_item_t*) notification);
1310 }
1311 
1312 void gatt_client_stop_listening_for_characteristic_value_updates(gatt_client_notification_t * notification){
1313     btstack_linked_list_remove(&gatt_client_value_listeners, (btstack_linked_item_t*) notification);
1314 }
1315 
1316 static bool is_value_valid(gatt_client_t *gatt_client, uint8_t *packet, uint16_t size){
1317     uint16_t attribute_handle = little_endian_read_16(packet, 1);
1318     uint16_t value_offset = little_endian_read_16(packet, 3);
1319 
1320     if (gatt_client->attribute_handle != attribute_handle) return false;
1321     if (gatt_client->attribute_offset != value_offset) return false;
1322     return memcmp(&gatt_client->attribute_value[gatt_client->attribute_offset], &packet[5], size - 5u) == 0u;
1323 }
1324 
1325 #ifdef ENABLE_LE_SIGNED_WRITE
1326 static void gatt_client_run_for_client_start_signed_write(gatt_client_t *gatt_client) {
1327     sm_key_t csrk;
1328     le_device_db_local_csrk_get(gatt_client->le_device_index, csrk);
1329     uint32_t sign_counter = le_device_db_local_counter_get(gatt_client->le_device_index);
1330     gatt_client->state = P_W4_CMAC_RESULT;
1331     sm_cmac_signed_write_start(csrk, ATT_SIGNED_WRITE_COMMAND, gatt_client->attribute_handle, gatt_client->attribute_length, gatt_client->attribute_value, sign_counter, att_signed_write_handle_cmac_result);
1332 }
1333 #endif
1334 
1335 // returns true if packet was sent
1336 static bool gatt_client_run_for_gatt_client(gatt_client_t * gatt_client){
1337 
1338     // wait until re-encryption is complete
1339     if (gap_reconnect_security_setup_active(gatt_client->con_handle)) return false;
1340 
1341     // wait until re-encryption is complete
1342     if (gatt_client->reencryption_active) return false;
1343 
1344     // wait until pairing complete (either reactive authentication or due to required security level)
1345     if (gatt_client->wait_for_authentication_complete) return false;
1346 
1347     bool client_request_pending = gatt_client->state != P_READY;
1348 
1349     // verify security level for Mandatory Authentication over LE
1350     bool check_security;
1351     switch (gatt_client->bearer_type){
1352         case ATT_BEARER_UNENHANCED_LE:
1353             check_security = true;
1354             break;
1355         default:
1356             check_security = false;
1357             break;
1358     }
1359     if (client_request_pending && (gatt_client_required_security_level > gatt_client->security_level) && check_security){
1360         log_info("Trigger pairing, current security level %u, required %u\n", gatt_client->security_level, gatt_client_required_security_level);
1361         gatt_client->wait_for_authentication_complete = true;
1362         // set att error code for pairing failure based on required level
1363         switch (gatt_client_required_security_level){
1364             case LEVEL_4:
1365             case LEVEL_3:
1366                 gatt_client->pending_error_code = ATT_ERROR_INSUFFICIENT_AUTHENTICATION;
1367                 break;
1368             default:
1369                 gatt_client->pending_error_code = ATT_ERROR_INSUFFICIENT_ENCRYPTION;
1370                 break;
1371         }
1372         sm_request_pairing(gatt_client->con_handle);
1373         // sm probably just sent a pdu
1374         return true;
1375     }
1376 
1377     switch (gatt_client->mtu_state) {
1378         case SEND_MTU_EXCHANGE:
1379             gatt_client->mtu_state = SENT_MTU_EXCHANGE;
1380             att_exchange_mtu_request(gatt_client);
1381             return true;
1382         case SENT_MTU_EXCHANGE:
1383             return false;
1384         default:
1385             break;
1386     }
1387 
1388     if (gatt_client->send_confirmation){
1389         gatt_client->send_confirmation = false;
1390         att_confirmation(gatt_client);
1391         return true;
1392     }
1393 
1394     // check MTU for writes
1395     switch (gatt_client->state){
1396         case P_W2_SEND_WRITE_CHARACTERISTIC_VALUE:
1397         case P_W2_SEND_WRITE_CHARACTERISTIC_DESCRIPTOR:
1398             if (gatt_client->attribute_length <= (gatt_client->mtu - 3u)) break;
1399             log_error("gatt_client_run: value len %u > MTU %u - 3\n", gatt_client->attribute_length,gatt_client->mtu);
1400             gatt_client_handle_transaction_complete(gatt_client, ATT_ERROR_INVALID_ATTRIBUTE_VALUE_LENGTH);
1401             return false;
1402         default:
1403             break;
1404     }
1405 
1406     bool packet_sent = true;
1407     bool done = true;
1408     switch (gatt_client->state){
1409         case P_W2_SEND_SERVICE_QUERY:
1410             gatt_client->state = P_W4_SERVICE_QUERY_RESULT;
1411             send_gatt_services_request(gatt_client);
1412             break;
1413 
1414         case P_W2_SEND_SERVICE_WITH_UUID_QUERY:
1415             gatt_client->state = P_W4_SERVICE_WITH_UUID_RESULT;
1416             send_gatt_services_by_uuid_request(gatt_client);
1417             break;
1418 
1419         case P_W2_SEND_ALL_CHARACTERISTICS_OF_SERVICE_QUERY:
1420             gatt_client->state = P_W4_ALL_CHARACTERISTICS_OF_SERVICE_QUERY_RESULT;
1421             send_gatt_characteristic_request(gatt_client);
1422             break;
1423 
1424         case P_W2_SEND_CHARACTERISTIC_WITH_UUID_QUERY:
1425             gatt_client->state = P_W4_CHARACTERISTIC_WITH_UUID_QUERY_RESULT;
1426             send_gatt_characteristic_request(gatt_client);
1427             break;
1428 
1429         case P_W2_SEND_ALL_CHARACTERISTIC_DESCRIPTORS_QUERY:
1430             gatt_client->state = P_W4_CHARACTERISTIC_WITH_UUID_QUERY_RESULT;
1431             send_gatt_characteristic_descriptor_request(gatt_client);
1432             break;
1433 
1434         case P_W2_SEND_INCLUDED_SERVICE_QUERY:
1435             gatt_client->state = P_W4_INCLUDED_SERVICE_QUERY_RESULT;
1436             send_gatt_included_service_request(gatt_client);
1437             break;
1438 
1439         case P_W2_SEND_INCLUDED_SERVICE_WITH_UUID_QUERY:
1440             gatt_client->state = P_W4_INCLUDED_SERVICE_UUID_WITH_QUERY_RESULT;
1441             send_gatt_included_service_uuid_request(gatt_client);
1442             break;
1443 
1444         case P_W2_SEND_READ_CHARACTERISTIC_VALUE_QUERY:
1445             gatt_client->state = P_W4_READ_CHARACTERISTIC_VALUE_RESULT;
1446             send_gatt_read_characteristic_value_request(gatt_client);
1447             break;
1448 
1449         case P_W2_SEND_READ_BLOB_QUERY:
1450             gatt_client->state = P_W4_READ_BLOB_RESULT;
1451             send_gatt_read_blob_request(gatt_client);
1452             break;
1453 
1454         case P_W2_SEND_READ_BY_TYPE_REQUEST:
1455             gatt_client->state = P_W4_READ_BY_TYPE_RESPONSE;
1456             send_gatt_read_by_type_request(gatt_client);
1457             break;
1458 
1459         case P_W2_SEND_READ_MULTIPLE_REQUEST:
1460             gatt_client->state = P_W4_READ_MULTIPLE_RESPONSE;
1461             send_gatt_read_multiple_request(gatt_client);
1462             break;
1463 
1464 #ifdef ENABLE_GATT_OVER_EATT
1465         case P_W2_SEND_READ_MULTIPLE_VARIABLE_REQUEST:
1466             gatt_client->state = P_W4_READ_MULTIPLE_VARIABLE_RESPONSE;
1467             send_gatt_read_multiple_variable_request(gatt_client);
1468             break;
1469 #endif
1470 
1471         case P_W2_SEND_WRITE_CHARACTERISTIC_VALUE:
1472             gatt_client->state = P_W4_WRITE_CHARACTERISTIC_VALUE_RESULT;
1473             send_gatt_write_attribute_value_request(gatt_client);
1474             break;
1475 
1476         case P_W2_PREPARE_WRITE:
1477             gatt_client->state = P_W4_PREPARE_WRITE_RESULT;
1478             send_gatt_prepare_write_request(gatt_client);
1479             break;
1480 
1481         case P_W2_PREPARE_WRITE_SINGLE:
1482             gatt_client->state = P_W4_PREPARE_WRITE_SINGLE_RESULT;
1483             send_gatt_prepare_write_request(gatt_client);
1484             break;
1485 
1486         case P_W2_PREPARE_RELIABLE_WRITE:
1487             gatt_client->state = P_W4_PREPARE_RELIABLE_WRITE_RESULT;
1488             send_gatt_prepare_write_request(gatt_client);
1489             break;
1490 
1491         case P_W2_EXECUTE_PREPARED_WRITE:
1492             gatt_client->state = P_W4_EXECUTE_PREPARED_WRITE_RESULT;
1493             send_gatt_execute_write_request(gatt_client);
1494             break;
1495 
1496         case P_W2_CANCEL_PREPARED_WRITE:
1497             gatt_client->state = P_W4_CANCEL_PREPARED_WRITE_RESULT;
1498             send_gatt_cancel_prepared_write_request(gatt_client);
1499             break;
1500 
1501         case P_W2_CANCEL_PREPARED_WRITE_DATA_MISMATCH:
1502             gatt_client->state = P_W4_CANCEL_PREPARED_WRITE_DATA_MISMATCH_RESULT;
1503             send_gatt_cancel_prepared_write_request(gatt_client);
1504             break;
1505 
1506 #ifdef ENABLE_GATT_FIND_INFORMATION_FOR_CCC_DISCOVERY
1507         case P_W2_SEND_FIND_CLIENT_CHARACTERISTIC_CONFIGURATION_QUERY:
1508             // use Find Information
1509             gatt_client->gatt_client_state = P_W4_FIND_CLIENT_CHARACTERISTIC_CONFIGURATION_QUERY_RESULT;
1510             send_gatt_characteristic_descriptor_request(gatt_client);
1511 #else
1512         case P_W2_SEND_READ_CLIENT_CHARACTERISTIC_CONFIGURATION_QUERY:
1513             // Use Read By Type
1514             gatt_client->state = P_W4_READ_CLIENT_CHARACTERISTIC_CONFIGURATION_QUERY_RESULT;
1515             send_gatt_read_client_characteristic_configuration_request(gatt_client);
1516 #endif
1517             break;
1518 
1519         case P_W2_SEND_READ_CHARACTERISTIC_DESCRIPTOR_QUERY:
1520             gatt_client->state = P_W4_READ_CHARACTERISTIC_DESCRIPTOR_RESULT;
1521             send_gatt_read_characteristic_descriptor_request(gatt_client);
1522             break;
1523 
1524         case P_W2_SEND_READ_BLOB_CHARACTERISTIC_DESCRIPTOR_QUERY:
1525             gatt_client->state = P_W4_READ_BLOB_CHARACTERISTIC_DESCRIPTOR_RESULT;
1526             send_gatt_read_blob_request(gatt_client);
1527             break;
1528 
1529         case P_W2_SEND_WRITE_CHARACTERISTIC_DESCRIPTOR:
1530             gatt_client->state = P_W4_WRITE_CHARACTERISTIC_DESCRIPTOR_RESULT;
1531             send_gatt_write_attribute_value_request(gatt_client);
1532             break;
1533 
1534         case P_W2_WRITE_CLIENT_CHARACTERISTIC_CONFIGURATION:
1535             gatt_client->state = P_W4_CLIENT_CHARACTERISTIC_CONFIGURATION_RESULT;
1536             send_gatt_write_client_characteristic_configuration_request(gatt_client);
1537             break;
1538 
1539         case P_W2_PREPARE_WRITE_CHARACTERISTIC_DESCRIPTOR:
1540             gatt_client->state = P_W4_PREPARE_WRITE_CHARACTERISTIC_DESCRIPTOR_RESULT;
1541             send_gatt_prepare_write_request(gatt_client);
1542             break;
1543 
1544         case P_W2_EXECUTE_PREPARED_WRITE_CHARACTERISTIC_DESCRIPTOR:
1545             gatt_client->state = P_W4_EXECUTE_PREPARED_WRITE_CHARACTERISTIC_DESCRIPTOR_RESULT;
1546             send_gatt_execute_write_request(gatt_client);
1547             break;
1548 
1549 #ifdef ENABLE_LE_SIGNED_WRITE
1550         case P_W4_IDENTITY_RESOLVING:
1551             log_info("P_W4_IDENTITY_RESOLVING - state %x", sm_identity_resolving_state(gatt_client->con_handle));
1552             switch (sm_identity_resolving_state(gatt_client->con_handle)){
1553                 case IRK_LOOKUP_SUCCEEDED:
1554                     gatt_client->le_device_index = sm_le_device_index(gatt_client->con_handle);
1555                     gatt_client->state = P_W4_CMAC_READY;
1556                     if (sm_cmac_ready()){
1557                         gatt_client_run_for_client_start_signed_write(gatt_client);
1558                     }
1559                     break;
1560                 case IRK_LOOKUP_FAILED:
1561                     gatt_client_handle_transaction_complete(gatt_client, ATT_ERROR_BONDING_INFORMATION_MISSING);
1562                     break;
1563                 default:
1564                     break;
1565             }
1566             packet_sent = false;
1567             break;
1568 
1569         case P_W4_CMAC_READY:
1570             if (sm_cmac_ready()){
1571                 gatt_client_run_for_client_start_signed_write(gatt_client);
1572             }
1573             packet_sent = false;
1574             break;
1575 
1576         case P_W2_SEND_SIGNED_WRITE: {
1577             gatt_client->state = P_W4_SEND_SIGNED_WRITE_DONE;
1578             // bump local signing counter
1579             uint32_t sign_counter = le_device_db_local_counter_get(gatt_client->le_device_index);
1580             le_device_db_local_counter_set(gatt_client->le_device_index, sign_counter + 1);
1581             // send signed write command
1582             send_gatt_signed_write_request(gatt_client, sign_counter);
1583             // finally, notifiy client that write is complete
1584             gatt_client_handle_transaction_complete(gatt_client, ATT_ERROR_SUCCESS);
1585             break;
1586         }
1587 #endif
1588         default:
1589             done = false;
1590             break;
1591     }
1592 
1593     if (done){
1594         return packet_sent;
1595     }
1596 
1597     // write without response callback
1598     btstack_context_callback_registration_t * callback =
1599             (btstack_context_callback_registration_t *) btstack_linked_list_pop(&gatt_client->write_without_response_requests);
1600     if (callback != NULL){
1601         (*callback->callback)(callback->context);
1602         return true;
1603     }
1604 
1605     // requested can send now old
1606     if (gatt_client->write_without_response_callback != NULL){
1607         btstack_packet_handler_t packet_handler = gatt_client->write_without_response_callback;
1608         gatt_client->write_without_response_callback = NULL;
1609         uint8_t event[4];
1610         event[0] = GATT_EVENT_CAN_WRITE_WITHOUT_RESPONSE;
1611         event[1] = sizeof(event) - 2u;
1612         little_endian_store_16(event, 2, gatt_client->con_handle);
1613         packet_handler(HCI_EVENT_PACKET, gatt_client->con_handle, event, sizeof(event));
1614         return true; // to trigger requeueing (even if higher layer didn't sent)
1615     }
1616 
1617     return false;
1618 }
1619 
1620 static void gatt_client_run(void){
1621     btstack_linked_item_t *it;
1622     bool packet_sent;
1623 #ifdef ENABLE_GATT_OVER_EATT
1624     btstack_linked_list_iterator_t it_eatt;
1625 #endif
1626     for (it = (btstack_linked_item_t *) gatt_client_connections; it != NULL; it = it->next){
1627         gatt_client_t * gatt_client = (gatt_client_t *) it;
1628         switch (gatt_client->bearer_type){
1629             case ATT_BEARER_UNENHANCED_LE:
1630 #ifdef ENABLE_GATT_OVER_EATT
1631                 btstack_linked_list_iterator_init(&it_eatt, &gatt_client->eatt_clients);
1632                 while (btstack_linked_list_iterator_has_next(&it_eatt)) {
1633                     gatt_client_t * eatt_client = (gatt_client_t *) btstack_linked_list_iterator_next(&it_eatt);
1634                     if (eatt_client->state != P_READY){
1635                         if (att_dispatch_client_can_send_now(gatt_client->con_handle)){
1636                             gatt_client_run_for_gatt_client(eatt_client);
1637                         }
1638                     }
1639                 }
1640 #endif
1641                 if (!att_dispatch_client_can_send_now(gatt_client->con_handle)) {
1642                     att_dispatch_client_request_can_send_now_event(gatt_client->con_handle);
1643                     return;
1644                 }
1645                 packet_sent = gatt_client_run_for_gatt_client(gatt_client);
1646                 if (packet_sent){
1647                     // request new permission
1648                     att_dispatch_client_request_can_send_now_event(gatt_client->con_handle);
1649                     // requeue client for fairness and exit
1650                     // note: iterator has become invalid
1651                     btstack_linked_list_remove(&gatt_client_connections, (btstack_linked_item_t *) gatt_client);
1652                     btstack_linked_list_add_tail(&gatt_client_connections, (btstack_linked_item_t *) gatt_client);
1653                     return;
1654                 }
1655                 break;
1656 #ifdef ENABLE_GATT_OVER_CLASSIC
1657             case ATT_BEARER_UNENHANCED_CLASSIC:
1658                 if (gatt_client->con_handle == HCI_CON_HANDLE_INVALID) {
1659                     continue;
1660                 }
1661 
1662                 // handle GATT over BR/EDR
1663                 if (att_dispatch_client_can_send_now(gatt_client->con_handle) == false) {
1664                     att_dispatch_client_request_can_send_now_event(gatt_client->con_handle);
1665                     return;
1666                 }
1667                 packet_sent = gatt_client_run_for_gatt_client(gatt_client);
1668                 if (packet_sent){
1669                     // request new permission
1670                     att_dispatch_client_request_can_send_now_event(gatt_client->con_handle);
1671                     // requeue client for fairness and exit
1672                     // note: iterator has become invalid
1673                     btstack_linked_list_remove(&gatt_client_connections, (btstack_linked_item_t *) gatt_client);
1674                     btstack_linked_list_add_tail(&gatt_client_connections, (btstack_linked_item_t *) gatt_client);
1675                     return;
1676                 }
1677                 break;
1678 #endif
1679             default:
1680                 btstack_unreachable();
1681                 break;
1682         }
1683 
1684 
1685     }
1686 }
1687 
1688 // emit complete event, used to avoid emitting event from API call
1689 static void gatt_client_emit_events(void * context){
1690     UNUSED(context);
1691     btstack_linked_item_t *it;
1692     for (it = (btstack_linked_item_t *) gatt_client_connections; it != NULL; it = it->next) {
1693         gatt_client_t *gatt_client = (gatt_client_t *) it;
1694         if (gatt_client->state == P_W2_EMIT_QUERY_COMPLETE_EVENT){
1695             gatt_client->state = P_READY;
1696             emit_gatt_complete_event(gatt_client, ATT_ERROR_SUCCESS);
1697         }
1698     }
1699 }
1700 
1701 static void gatt_client_report_error_if_pending(gatt_client_t *gatt_client, uint8_t att_error_code) {
1702     if (is_ready(gatt_client)) return;
1703     gatt_client_handle_transaction_complete(gatt_client, att_error_code);
1704 }
1705 
1706 static void gatt_client_handle_reencryption_complete(const uint8_t * packet){
1707     hci_con_handle_t con_handle = sm_event_reencryption_complete_get_handle(packet);
1708     gatt_client_t * gatt_client = gatt_client_get_context_for_handle(con_handle);
1709     if (gatt_client == NULL) return;
1710 
1711     // update security level
1712     gatt_client->security_level = gatt_client_le_security_level_for_connection(con_handle);
1713 
1714     gatt_client->reencryption_result = sm_event_reencryption_complete_get_status(packet);
1715     gatt_client->reencryption_active = false;
1716     gatt_client->wait_for_authentication_complete = false;
1717 
1718     if (gatt_client->state == P_READY) return;
1719 
1720     switch (sm_event_reencryption_complete_get_status(packet)){
1721         case ERROR_CODE_SUCCESS:
1722             log_info("re-encryption success, retry operation");
1723             break;
1724         case ERROR_CODE_AUTHENTICATION_FAILURE:
1725         case ERROR_CODE_PIN_OR_KEY_MISSING:
1726 #if defined(ENABLE_GATT_CLIENT_PAIRING) && !defined(ENABLE_LE_PROACTIVE_AUTHENTICATION)
1727             if (gatt_client_required_security_level == LEVEL_0) {
1728                 // re-encryption failed for reactive authentication with pairing and we have a pending client request
1729                 // => try to resolve it by deleting bonding information if we started pairing before
1730                 // delete bonding information
1731                 int le_device_db_index = sm_le_device_index(gatt_client->con_handle);
1732                 btstack_assert(le_device_db_index >= 0);
1733                 log_info("reactive auth with pairing: delete bonding and start pairing");
1734 #ifdef ENABLE_LE_PRIVACY_ADDRESS_RESOLUTION
1735                 hci_remove_le_device_db_entry_from_resolving_list((uint16_t) le_device_db_index);
1736 #endif
1737                 le_device_db_remove(le_device_db_index);
1738                 // trigger pairing again
1739                 sm_request_pairing(gatt_client->con_handle);
1740                 break;
1741             }
1742 #endif
1743             // report bonding information missing
1744             gatt_client_handle_transaction_complete(gatt_client, ATT_ERROR_BONDING_INFORMATION_MISSING);
1745             break;
1746         default:
1747             // report bonding information missing
1748             gatt_client_handle_transaction_complete(gatt_client, gatt_client->pending_error_code);
1749             break;
1750     }
1751 }
1752 
1753 static void gatt_client_handle_disconnection_complete(const uint8_t * packet){
1754     log_info("GATT Client: HCI_EVENT_DISCONNECTION_COMPLETE");
1755     hci_con_handle_t con_handle = little_endian_read_16(packet,3);
1756     gatt_client_t * gatt_client = gatt_client_get_context_for_handle(con_handle);
1757     if (gatt_client == NULL) return;
1758 
1759     gatt_client_report_error_if_pending(gatt_client, ATT_ERROR_HCI_DISCONNECT_RECEIVED);
1760     gatt_client_timeout_stop(gatt_client);
1761     btstack_linked_list_remove(&gatt_client_connections, (btstack_linked_item_t *) gatt_client);
1762     btstack_memory_gatt_client_free(gatt_client);
1763 }
1764 
1765 static void gatt_client_event_packet_handler(uint8_t packet_type, uint16_t channel, uint8_t *packet, uint16_t size){
1766     UNUSED(channel);    // ok: handling own l2cap events
1767     UNUSED(size);       // ok: there is no channel
1768 
1769     if (packet_type != HCI_EVENT_PACKET) return;
1770 
1771     hci_con_handle_t con_handle;
1772     gatt_client_t * gatt_client;
1773     switch (hci_event_packet_get_type(packet)) {
1774         case HCI_EVENT_DISCONNECTION_COMPLETE:
1775             gatt_client_handle_disconnection_complete(packet);
1776             break;
1777 
1778         // Pairing complete (with/without bonding=storing of pairing information)
1779         case SM_EVENT_PAIRING_COMPLETE:
1780             con_handle = sm_event_pairing_complete_get_handle(packet);
1781             gatt_client = gatt_client_get_context_for_handle(con_handle);
1782             if (gatt_client == NULL) break;
1783 
1784             // update security level
1785             gatt_client->security_level = gatt_client_le_security_level_for_connection(con_handle);
1786 
1787             if (gatt_client->wait_for_authentication_complete){
1788                 gatt_client->wait_for_authentication_complete = false;
1789                 if (sm_event_pairing_complete_get_status(packet) != ERROR_CODE_SUCCESS){
1790                     log_info("pairing failed, report previous error 0x%x", gatt_client->pending_error_code);
1791                     gatt_client_report_error_if_pending(gatt_client, gatt_client->pending_error_code);
1792                 } else {
1793                     log_info("pairing success, retry operation");
1794                 }
1795             }
1796             break;
1797 
1798 #ifdef ENABLE_LE_SIGNED_WRITE
1799         // Identity Resolving completed (no code, gatt_client_run will continue)
1800         case SM_EVENT_IDENTITY_RESOLVING_SUCCEEDED:
1801         case SM_EVENT_IDENTITY_RESOLVING_FAILED:
1802             break;
1803 #endif
1804 
1805         // re-encryption started
1806         case SM_EVENT_REENCRYPTION_STARTED:
1807             con_handle = sm_event_reencryption_complete_get_handle(packet);
1808             gatt_client = gatt_client_get_context_for_handle(con_handle);
1809             if (gatt_client == NULL) break;
1810 
1811             gatt_client->reencryption_active = true;
1812             gatt_client->reencryption_result = ERROR_CODE_SUCCESS;
1813             break;
1814 
1815         // re-encryption complete
1816         case SM_EVENT_REENCRYPTION_COMPLETE:
1817             gatt_client_handle_reencryption_complete(packet);
1818             break;
1819         default:
1820             break;
1821     }
1822 
1823     gatt_client_run();
1824 }
1825 
1826 static void gatt_client_handle_att_read_response(gatt_client_t *gatt_client, uint8_t *packet, uint16_t size) {
1827     switch (gatt_client->state) {
1828         case P_W4_INCLUDED_SERVICE_UUID_WITH_QUERY_RESULT:
1829             if (size >= 17) {
1830                 uint8_t uuid128[16];
1831                 reverse_128(&packet[1], uuid128);
1832                 report_gatt_included_service_uuid128(gatt_client, gatt_client->start_group_handle, uuid128);
1833             }
1834             trigger_next_included_service_query(gatt_client, gatt_client->start_group_handle);
1835             // GATT_EVENT_QUERY_COMPLETE is emitted by trigger_next_xxx when done
1836             break;
1837 
1838         case P_W4_READ_CHARACTERISTIC_VALUE_RESULT:
1839             report_gatt_characteristic_value(gatt_client, gatt_client->attribute_handle, &packet[1], size - 1u);
1840             gatt_client_handle_transaction_complete(gatt_client, ATT_ERROR_SUCCESS);
1841             break;
1842 
1843         case P_W4_READ_CHARACTERISTIC_DESCRIPTOR_RESULT:
1844             report_gatt_characteristic_descriptor(gatt_client, gatt_client->attribute_handle, &packet[1],
1845                                                   size - 1u, 0u);
1846             gatt_client_handle_transaction_complete(gatt_client, ATT_ERROR_SUCCESS);
1847             break;
1848 
1849             // Use ATT_READ_REQUEST for first blob of Read Long Characteristic
1850         case P_W4_READ_BLOB_RESULT:
1851             report_gatt_long_characteristic_value_blob(gatt_client, gatt_client->attribute_handle, &packet[1],
1852                                                        size - 1u, gatt_client->attribute_offset);
1853             trigger_next_blob_query(gatt_client, P_W2_SEND_READ_BLOB_QUERY, size - 1u);
1854             // GATT_EVENT_QUERY_COMPLETE is emitted by trigger_next_xxx when done
1855             break;
1856 
1857             // Use ATT_READ_REQUEST for first blob of Read Long Characteristic Descriptor
1858         case P_W4_READ_BLOB_CHARACTERISTIC_DESCRIPTOR_RESULT:
1859             report_gatt_long_characteristic_descriptor(gatt_client, gatt_client->attribute_handle, &packet[1],
1860                                                        size - 1u, gatt_client->attribute_offset);
1861             trigger_next_blob_query(gatt_client, P_W2_SEND_READ_BLOB_CHARACTERISTIC_DESCRIPTOR_QUERY,
1862                                     size - 1u);
1863             // GATT_EVENT_QUERY_COMPLETE is emitted by trigger_next_xxx when done
1864             break;
1865 
1866         default:
1867             break;
1868     }
1869 }
1870 
1871 static void gatt_client_handle_att_read_by_type_response(gatt_client_t *gatt_client, uint8_t *packet, uint16_t size) {
1872     switch (gatt_client->state) {
1873         case P_W4_ALL_CHARACTERISTICS_OF_SERVICE_QUERY_RESULT:
1874             report_gatt_characteristics(gatt_client, packet, size);
1875             trigger_next_characteristic_query(gatt_client,
1876                                               get_last_result_handle_from_characteristics_list(packet, size));
1877             // GATT_EVENT_QUERY_COMPLETE is emitted by trigger_next_xxx when done, or by ATT_ERROR
1878             break;
1879         case P_W4_CHARACTERISTIC_WITH_UUID_QUERY_RESULT:
1880             report_gatt_characteristics(gatt_client, packet, size);
1881             trigger_next_characteristic_query(gatt_client,
1882                                               get_last_result_handle_from_characteristics_list(packet, size));
1883             // GATT_EVENT_QUERY_COMPLETE is emitted by trigger_next_xxx when done, or by ATT_ERROR
1884             break;
1885         case P_W4_INCLUDED_SERVICE_QUERY_RESULT: {
1886             if (size < 2u) break;
1887             uint16_t uuid16 = 0;
1888             uint16_t pair_size = packet[1];
1889 
1890             if (pair_size == 6u) {
1891                 if (size < 8u) break;
1892                 // UUIDs not available, query first included service
1893                 gatt_client->start_group_handle = little_endian_read_16(packet, 2); // ready for next query
1894                 gatt_client->query_start_handle = little_endian_read_16(packet, 4);
1895                 gatt_client->query_end_handle = little_endian_read_16(packet, 6);
1896                 gatt_client->state = P_W2_SEND_INCLUDED_SERVICE_WITH_UUID_QUERY;
1897                 break;
1898             }
1899 
1900             if (pair_size != 8u) break;
1901 
1902             // UUIDs included, report all of them
1903             uint16_t offset;
1904             for (offset = 2u; (offset + 8u) <= size; offset += pair_size) {
1905                 uint16_t include_handle = little_endian_read_16(packet, offset);
1906                 gatt_client->query_start_handle = little_endian_read_16(packet, offset + 2u);
1907                 gatt_client->query_end_handle = little_endian_read_16(packet, offset + 4u);
1908                 uuid16 = little_endian_read_16(packet, offset + 6u);
1909                 report_gatt_included_service_uuid16(gatt_client, include_handle, uuid16);
1910             }
1911 
1912             trigger_next_included_service_query(gatt_client,
1913                                                 get_last_result_handle_from_included_services_list(packet,
1914                                                                                                    size));
1915             // GATT_EVENT_QUERY_COMPLETE is emitted by trigger_next_xxx when done
1916             break;
1917         }
1918 #ifndef ENABLE_GATT_FIND_INFORMATION_FOR_CCC_DISCOVERY
1919         case P_W4_READ_CLIENT_CHARACTERISTIC_CONFIGURATION_QUERY_RESULT:
1920             gatt_client->client_characteristic_configuration_handle = little_endian_read_16(packet, 2);
1921             gatt_client->state = P_W2_WRITE_CLIENT_CHARACTERISTIC_CONFIGURATION;
1922             break;
1923 #endif
1924         case P_W4_READ_BY_TYPE_RESPONSE: {
1925             uint16_t pair_size = packet[1];
1926             // set last result handle to last valid handle, only used if pair_size invalid
1927             uint16_t last_result_handle = 0xffff;
1928             if (pair_size > 2) {
1929                 uint16_t offset;
1930                 for (offset = 2; offset < size; offset += pair_size) {
1931                     uint16_t value_handle = little_endian_read_16(packet, offset);
1932                     report_gatt_characteristic_value(gatt_client, value_handle, &packet[offset + 2u],
1933                                                      pair_size - 2u);
1934                     last_result_handle = value_handle;
1935                 }
1936             }
1937             trigger_next_read_by_type_query(gatt_client, last_result_handle);
1938             break;
1939         }
1940         default:
1941             break;
1942     }
1943 }
1944 
1945 static void gatt_client_handle_att_write_response(gatt_client_t *gatt_client) {
1946     switch (gatt_client->state) {
1947         case P_W4_WRITE_CHARACTERISTIC_VALUE_RESULT:
1948             gatt_client_handle_transaction_complete(gatt_client, ATT_ERROR_SUCCESS);
1949             break;
1950         case P_W4_CLIENT_CHARACTERISTIC_CONFIGURATION_RESULT:
1951             gatt_client_handle_transaction_complete(gatt_client, ATT_ERROR_SUCCESS);
1952             break;
1953         case P_W4_WRITE_CHARACTERISTIC_DESCRIPTOR_RESULT:
1954             gatt_client_handle_transaction_complete(gatt_client, ATT_ERROR_SUCCESS);
1955             break;
1956         default:
1957             break;
1958     }
1959 }
1960 
1961 static void gatt_client_handle_att_response(gatt_client_t * gatt_client, uint8_t * packet, uint16_t size) {
1962     uint8_t att_status;
1963     switch (packet[0]) {
1964         case ATT_EXCHANGE_MTU_RESPONSE: {
1965             if (size < 3u) break;
1966             bool update_gatt_server_att_mtu = false;
1967             uint16_t remote_rx_mtu = little_endian_read_16(packet, 1);
1968             uint16_t local_rx_mtu = l2cap_max_le_mtu();
1969             switch (gatt_client->bearer_type){
1970                 case ATT_BEARER_UNENHANCED_LE:
1971                     update_gatt_server_att_mtu = true;
1972                     break;
1973 #ifdef ENABLE_GATT_OVER_CLASSIC
1974                 case ATT_BEARER_UNENHANCED_CLASSIC:
1975                     local_rx_mtu = gatt_client->mtu;
1976                     break;
1977 #endif
1978                 default:
1979                     btstack_unreachable();
1980                     break;
1981             }
1982 
1983             uint16_t mtu = (remote_rx_mtu < local_rx_mtu) ? remote_rx_mtu : local_rx_mtu;
1984 
1985             // set gatt client mtu
1986             gatt_client->mtu = mtu;
1987             gatt_client->mtu_state = MTU_EXCHANGED;
1988 
1989             if (update_gatt_server_att_mtu){
1990                 // set per connection mtu state - for fixed channel
1991                 hci_connection_t *hci_connection = hci_connection_for_handle(gatt_client->con_handle);
1992                 hci_connection->att_connection.mtu = gatt_client->mtu;
1993                 hci_connection->att_connection.mtu_exchanged = true;
1994             }
1995             emit_gatt_mtu_exchanged_result_event(gatt_client, gatt_client->mtu);
1996             break;
1997         }
1998         case ATT_READ_BY_GROUP_TYPE_RESPONSE:
1999             switch (gatt_client->state) {
2000                 case P_W4_SERVICE_QUERY_RESULT:
2001                     report_gatt_services(gatt_client, packet, size);
2002                     trigger_next_service_query(gatt_client, get_last_result_handle_from_service_list(packet, size));
2003                     // GATT_EVENT_QUERY_COMPLETE is emitted by trigger_next_xxx when done
2004                     break;
2005                 default:
2006                     break;
2007             }
2008             break;
2009         case ATT_HANDLE_VALUE_NOTIFICATION:
2010             if (size < 3u) return;
2011             report_gatt_notification(gatt_client, little_endian_read_16(packet, 1u), &packet[3], size - 3u);
2012             return;
2013 #ifdef ENABLE_GATT_OVER_EATT
2014         case ATT_MULTIPLE_HANDLE_VALUE_NTF:
2015             if (size >= 5u) {
2016                 uint16_t offset = 1;
2017                 while (true){
2018                     uint16_t value_handle = little_endian_read_16(packet, offset);
2019                     offset += 2;
2020                     uint16_t value_length = little_endian_read_16(packet, offset);
2021                     offset += 2;
2022                     if ((offset + value_length) > size) break;
2023                     report_gatt_notification(gatt_client, value_handle, &packet[offset], value_length);
2024                     offset += value_length;
2025                 }
2026             }
2027             return;
2028 #endif
2029         case ATT_HANDLE_VALUE_INDICATION:
2030             if (size < 3u) break;
2031             report_gatt_indication(gatt_client, little_endian_read_16(packet, 1u), &packet[3], size - 3u);
2032             gatt_client->send_confirmation = true;
2033             break;
2034         case ATT_READ_BY_TYPE_RESPONSE:
2035             gatt_client_handle_att_read_by_type_response(gatt_client, packet, size);
2036             break;
2037         case ATT_READ_RESPONSE:
2038             gatt_client_handle_att_read_response(gatt_client, packet, size);
2039             break;
2040         case ATT_FIND_BY_TYPE_VALUE_RESPONSE: {
2041             uint8_t pair_size = 4;
2042             int i;
2043             uint16_t start_group_handle;
2044             uint16_t end_group_handle = 0xffff; // asserts GATT_EVENT_QUERY_COMPLETE is emitted if no results
2045             for (i = 1u; (i + pair_size) <= size; i += pair_size) {
2046                 start_group_handle = little_endian_read_16(packet, i);
2047                 end_group_handle = little_endian_read_16(packet, i + 2);
2048                 emit_gatt_service_query_result_event(gatt_client, start_group_handle, end_group_handle,
2049                                                      gatt_client->uuid128);
2050             }
2051             trigger_next_service_by_uuid_query(gatt_client, end_group_handle);
2052             // GATT_EVENT_QUERY_COMPLETE is emitted by trigger_next_xxx when done
2053             break;
2054         }
2055         case ATT_FIND_INFORMATION_REPLY: {
2056             if (size < 2u) break;
2057 
2058             uint8_t pair_size = 4;
2059             if (packet[1u] == 2u) {
2060                 pair_size = 18;
2061             }
2062             uint16_t offset = 2;
2063 
2064             if (size < (pair_size + offset)) break;
2065             uint16_t last_descriptor_handle = little_endian_read_16(packet, size - pair_size);
2066 
2067 #ifdef ENABLE_GATT_FIND_INFORMATION_FOR_CCC_DISCOVERY
2068             log_info("ENABLE_GATT_FIND_INFORMATION_FOR_CCC_DISCOVERY, state %x", gatt_client->gatt_client_state);
2069             if (gatt_client->gatt_client_state == P_W4_FIND_CLIENT_CHARACTERISTIC_CONFIGURATION_QUERY_RESULT){
2070                 // iterate over descriptors looking for CCC
2071                 if (pair_size == 4){
2072                     while ((offset + 4) <= size){
2073                         uint16_t uuid16 = little_endian_read_16(packet, offset + 2);
2074                         if (uuid16 == GATT_CLIENT_CHARACTERISTICS_CONFIGURATION){
2075                             gatt_client->client_characteristic_configuration_handle = little_endian_read_16(packet, offset);
2076                             gatt_client->gatt_client_state = P_W2_WRITE_CLIENT_CHARACTERISTIC_CONFIGURATION;
2077                             log_info("CCC found %x", gatt_client->client_characteristic_configuration_handle);
2078                             break;
2079                         }
2080                         offset += pair_size;
2081                     }
2082                 }
2083                 if (is_query_done(gatt_client, last_descriptor_handle)){
2084 
2085                 } else {
2086                     // next
2087                     gatt_client->start_group_handle = last_descriptor_handle + 1;
2088                     gatt_client->gatt_client_state = P_W2_SEND_FIND_CLIENT_CHARACTERISTIC_CONFIGURATION_QUERY;
2089                 }
2090                 break;
2091             }
2092 #endif
2093             report_gatt_all_characteristic_descriptors(gatt_client, &packet[2], size - 2u, pair_size);
2094             trigger_next_characteristic_descriptor_query(gatt_client, last_descriptor_handle);
2095             // GATT_EVENT_QUERY_COMPLETE is emitted by trigger_next_xxx when done
2096             break;
2097         }
2098 
2099         case ATT_WRITE_RESPONSE:
2100             gatt_client_handle_att_write_response(gatt_client);
2101             break;
2102 
2103         case ATT_READ_BLOB_RESPONSE: {
2104             uint16_t received_blob_length = size - 1u;
2105             switch (gatt_client->state) {
2106                 case P_W4_READ_BLOB_RESULT:
2107                     report_gatt_long_characteristic_value_blob(gatt_client, gatt_client->attribute_handle, &packet[1],
2108                                                                received_blob_length, gatt_client->attribute_offset);
2109                     trigger_next_blob_query(gatt_client, P_W2_SEND_READ_BLOB_QUERY, received_blob_length);
2110                     // GATT_EVENT_QUERY_COMPLETE is emitted by trigger_next_xxx when done
2111                     break;
2112                 case P_W4_READ_BLOB_CHARACTERISTIC_DESCRIPTOR_RESULT:
2113                     report_gatt_long_characteristic_descriptor(gatt_client, gatt_client->attribute_handle,
2114                                                                &packet[1], received_blob_length,
2115                                                                gatt_client->attribute_offset);
2116                     trigger_next_blob_query(gatt_client, P_W2_SEND_READ_BLOB_CHARACTERISTIC_DESCRIPTOR_QUERY,
2117                                             received_blob_length);
2118                     // GATT_EVENT_QUERY_COMPLETE is emitted by trigger_next_xxx when done
2119                     break;
2120                 default:
2121                     break;
2122             }
2123             break;
2124         }
2125         case ATT_PREPARE_WRITE_RESPONSE:
2126             switch (gatt_client->state) {
2127                 case P_W4_PREPARE_WRITE_SINGLE_RESULT:
2128                     if (is_value_valid(gatt_client, packet, size)) {
2129                         att_status = ATT_ERROR_SUCCESS;
2130                     } else {
2131                         att_status = ATT_ERROR_DATA_MISMATCH;
2132                     }
2133                     gatt_client_handle_transaction_complete(gatt_client, att_status);
2134                     break;
2135 
2136                 case P_W4_PREPARE_WRITE_RESULT: {
2137                     gatt_client->attribute_offset = little_endian_read_16(packet, 3);
2138                     trigger_next_prepare_write_query(gatt_client, P_W2_PREPARE_WRITE, P_W2_EXECUTE_PREPARED_WRITE);
2139                     // GATT_EVENT_QUERY_COMPLETE is emitted by trigger_next_xxx when done
2140                     break;
2141                 }
2142                 case P_W4_PREPARE_WRITE_CHARACTERISTIC_DESCRIPTOR_RESULT: {
2143                     gatt_client->attribute_offset = little_endian_read_16(packet, 3);
2144                     trigger_next_prepare_write_query(gatt_client, P_W2_PREPARE_WRITE_CHARACTERISTIC_DESCRIPTOR,
2145                                                      P_W2_EXECUTE_PREPARED_WRITE_CHARACTERISTIC_DESCRIPTOR);
2146                     // GATT_EVENT_QUERY_COMPLETE is emitted by trigger_next_xxx when done
2147                     break;
2148                 }
2149                 case P_W4_PREPARE_RELIABLE_WRITE_RESULT: {
2150                     if (is_value_valid(gatt_client, packet, size)) {
2151                         gatt_client->attribute_offset = little_endian_read_16(packet, 3);
2152                         trigger_next_prepare_write_query(gatt_client, P_W2_PREPARE_RELIABLE_WRITE,
2153                                                          P_W2_EXECUTE_PREPARED_WRITE);
2154                         // GATT_EVENT_QUERY_COMPLETE is emitted by trigger_next_xxx when done
2155                         break;
2156                     }
2157                     gatt_client->state = P_W2_CANCEL_PREPARED_WRITE_DATA_MISMATCH;
2158                     break;
2159                 }
2160                 default:
2161                     break;
2162             }
2163             break;
2164 
2165         case ATT_EXECUTE_WRITE_RESPONSE:
2166             switch (gatt_client->state) {
2167                 case P_W4_EXECUTE_PREPARED_WRITE_RESULT:
2168                     gatt_client_handle_transaction_complete(gatt_client, ATT_ERROR_SUCCESS);
2169                     break;
2170                 case P_W4_CANCEL_PREPARED_WRITE_RESULT:
2171                     gatt_client_handle_transaction_complete(gatt_client, ATT_ERROR_SUCCESS);
2172                     break;
2173                 case P_W4_CANCEL_PREPARED_WRITE_DATA_MISMATCH_RESULT:
2174                     gatt_client_handle_transaction_complete(gatt_client, ATT_ERROR_DATA_MISMATCH);
2175                     break;
2176                 case P_W4_EXECUTE_PREPARED_WRITE_CHARACTERISTIC_DESCRIPTOR_RESULT:
2177                     gatt_client_handle_transaction_complete(gatt_client, ATT_ERROR_SUCCESS);
2178                     break;
2179                 default:
2180                     break;
2181 
2182             }
2183             break;
2184 
2185         case ATT_READ_MULTIPLE_RESPONSE:
2186             switch (gatt_client->state) {
2187                 case P_W4_READ_MULTIPLE_RESPONSE:
2188                     report_gatt_characteristic_value(gatt_client, 0u, &packet[1], size - 1u);
2189                     gatt_client_handle_transaction_complete(gatt_client, ATT_ERROR_SUCCESS);
2190                     break;
2191                 default:
2192                     break;
2193             }
2194             break;
2195 
2196 #ifdef ENABLE_GATT_OVER_EATT
2197         case ATT_READ_MULTIPLE_VARIABLE_RSP:
2198             switch (gatt_client->state) {
2199                 case P_W4_READ_MULTIPLE_VARIABLE_RESPONSE:
2200                     report_gatt_characteristic_value(gatt_client, 0u, &packet[1], size - 1u);
2201                     gatt_client_handle_transaction_complete(gatt_client, ATT_ERROR_SUCCESS);
2202                     break;
2203                 default:
2204                     break;
2205             }
2206             break;
2207 #endif
2208 
2209         case ATT_ERROR_RESPONSE:
2210             if (size < 5u) return;
2211             att_status = packet[4];
2212             switch (att_status) {
2213                 case ATT_ERROR_ATTRIBUTE_NOT_FOUND: {
2214                     switch (gatt_client->state) {
2215                         case P_W4_SERVICE_QUERY_RESULT:
2216                         case P_W4_SERVICE_WITH_UUID_RESULT:
2217                         case P_W4_INCLUDED_SERVICE_QUERY_RESULT:
2218                         case P_W4_ALL_CHARACTERISTIC_DESCRIPTORS_QUERY_RESULT:
2219                             gatt_client_handle_transaction_complete(gatt_client, ATT_ERROR_SUCCESS);
2220                             break;
2221                         case P_W4_ALL_CHARACTERISTICS_OF_SERVICE_QUERY_RESULT:
2222                         case P_W4_CHARACTERISTIC_WITH_UUID_QUERY_RESULT:
2223                             report_gatt_characteristic_end_found(gatt_client, gatt_client->end_group_handle);
2224                             gatt_client_handle_transaction_complete(gatt_client, ATT_ERROR_SUCCESS);
2225                             break;
2226                         case P_W4_READ_BY_TYPE_RESPONSE:
2227                             if (gatt_client->start_group_handle == gatt_client->query_start_handle) {
2228                                 att_status = ATT_ERROR_ATTRIBUTE_NOT_FOUND;
2229                             } else {
2230                                 att_status = ATT_ERROR_SUCCESS;
2231                             }
2232                             gatt_client_handle_transaction_complete(gatt_client, att_status);
2233                             break;
2234                         default:
2235                             gatt_client_report_error_if_pending(gatt_client, att_status);
2236                             break;
2237                     }
2238                     break;
2239                 }
2240 
2241 #ifdef ENABLE_GATT_CLIENT_PAIRING
2242 
2243                     case ATT_ERROR_INSUFFICIENT_AUTHENTICATION:
2244                     case ATT_ERROR_INSUFFICIENT_ENCRYPTION_KEY_SIZE:
2245                     case ATT_ERROR_INSUFFICIENT_ENCRYPTION: {
2246 
2247                         // security too low
2248                         if (gatt_client->security_counter > 0) {
2249                             gatt_client_report_error_if_pending(gatt_client, att_status);
2250                             break;
2251                         }
2252                         // start security
2253                         gatt_client->security_counter++;
2254 
2255                         // setup action
2256                         int retry = 1;
2257                         switch (gatt_client->state){
2258                             case P_W4_READ_CHARACTERISTIC_VALUE_RESULT:
2259                                 gatt_client->state = P_W2_SEND_READ_CHARACTERISTIC_VALUE_QUERY ;
2260                                 break;
2261                             case P_W4_READ_BLOB_RESULT:
2262                                 gatt_client->state = P_W2_SEND_READ_BLOB_QUERY;
2263                                 break;
2264                             case P_W4_READ_BY_TYPE_RESPONSE:
2265                                 gatt_client->state = P_W2_SEND_READ_BY_TYPE_REQUEST;
2266                                 break;
2267                             case P_W4_READ_MULTIPLE_RESPONSE:
2268                                 gatt_client->state = P_W2_SEND_READ_MULTIPLE_REQUEST;
2269                                 break;
2270                             case P_W4_READ_MULTIPLE_VARIABLE_RESPONSE:
2271                                 gatt_client->state = P_W2_SEND_READ_MULTIPLE_VARIABLE_REQUEST;
2272                                 break;
2273                             case P_W4_WRITE_CHARACTERISTIC_VALUE_RESULT:
2274                                 gatt_client->state = P_W2_SEND_WRITE_CHARACTERISTIC_VALUE;
2275                                 break;
2276                             case P_W4_PREPARE_WRITE_RESULT:
2277                                 gatt_client->state = P_W2_PREPARE_WRITE;
2278                                 break;
2279                             case P_W4_PREPARE_WRITE_SINGLE_RESULT:
2280                                 gatt_client->state = P_W2_PREPARE_WRITE_SINGLE;
2281                                 break;
2282                             case P_W4_PREPARE_RELIABLE_WRITE_RESULT:
2283                                 gatt_client->state = P_W2_PREPARE_RELIABLE_WRITE;
2284                                 break;
2285                             case P_W4_EXECUTE_PREPARED_WRITE_RESULT:
2286                                 gatt_client->state = P_W2_EXECUTE_PREPARED_WRITE;
2287                                 break;
2288                             case P_W4_CANCEL_PREPARED_WRITE_RESULT:
2289                                 gatt_client->state = P_W2_CANCEL_PREPARED_WRITE;
2290                                 break;
2291                             case P_W4_CANCEL_PREPARED_WRITE_DATA_MISMATCH_RESULT:
2292                                 gatt_client->state = P_W2_CANCEL_PREPARED_WRITE_DATA_MISMATCH;
2293                                 break;
2294                             case P_W4_READ_CHARACTERISTIC_DESCRIPTOR_RESULT:
2295                                 gatt_client->state = P_W2_SEND_READ_CHARACTERISTIC_DESCRIPTOR_QUERY;
2296                                 break;
2297                             case P_W4_READ_BLOB_CHARACTERISTIC_DESCRIPTOR_RESULT:
2298                                 gatt_client->state = P_W2_SEND_READ_BLOB_CHARACTERISTIC_DESCRIPTOR_QUERY;
2299                                 break;
2300                             case P_W4_WRITE_CHARACTERISTIC_DESCRIPTOR_RESULT:
2301                                 gatt_client->state = P_W2_SEND_WRITE_CHARACTERISTIC_DESCRIPTOR;
2302                                 break;
2303                             case P_W4_CLIENT_CHARACTERISTIC_CONFIGURATION_RESULT:
2304                                 gatt_client->state = P_W2_WRITE_CLIENT_CHARACTERISTIC_CONFIGURATION;
2305                                 break;
2306                             case P_W4_PREPARE_WRITE_CHARACTERISTIC_DESCRIPTOR_RESULT:
2307                                 gatt_client->state = P_W2_PREPARE_WRITE_CHARACTERISTIC_DESCRIPTOR;
2308                                 break;
2309                             case P_W4_EXECUTE_PREPARED_WRITE_CHARACTERISTIC_DESCRIPTOR_RESULT:
2310                                 gatt_client->state = P_W2_EXECUTE_PREPARED_WRITE_CHARACTERISTIC_DESCRIPTOR;
2311                                 break;
2312 #ifdef ENABLE_LE_SIGNED_WRITE
2313                             case P_W4_SEND_SIGNED_WRITE_DONE:
2314                                 gatt_client->state = P_W2_SEND_SIGNED_WRITE;
2315                                 break;
2316 #endif
2317                             default:
2318                                 log_info("retry not supported for state %x", gatt_client->state);
2319                                 retry = 0;
2320                                 break;
2321                         }
2322 
2323                         if (!retry) {
2324                             gatt_client_report_error_if_pending(gatt_client, att_status);
2325                             break;
2326                         }
2327 
2328                         log_info("security error, start pairing");
2329 
2330                         // start pairing for higher security level
2331                         gatt_client->wait_for_authentication_complete = true;
2332                         gatt_client->pending_error_code = att_status;
2333                         sm_request_pairing(gatt_client->con_handle);
2334                         break;
2335                     }
2336 #endif
2337 
2338                     // nothing we can do about that
2339                 case ATT_ERROR_INSUFFICIENT_AUTHORIZATION:
2340                 default:
2341                     gatt_client_report_error_if_pending(gatt_client, att_status);
2342                     break;
2343             }
2344             break;
2345 
2346         default:
2347             log_info("ATT Handler, unhandled response type 0x%02x", packet[0]);
2348             break;
2349     }
2350 }
2351 
2352 static void gatt_client_att_packet_handler(uint8_t packet_type, uint16_t handle, uint8_t *packet, uint16_t size) {
2353     gatt_client_t *gatt_client;
2354 #ifdef ENABLE_GATT_OVER_CLASSIC
2355     uint8_t status;
2356     hci_connection_t * hci_connection;
2357     hci_con_handle_t con_handle;
2358 #endif
2359 
2360     if (size < 1u) return;
2361     switch (packet_type){
2362         case HCI_EVENT_PACKET:
2363             switch (hci_event_packet_get_type(packet)) {
2364 #ifdef ENABLE_GATT_OVER_CLASSIC
2365                 case L2CAP_EVENT_CHANNEL_OPENED:
2366                     status = l2cap_event_channel_opened_get_status(packet);
2367                     gatt_client = gatt_client_get_context_for_l2cap_cid(l2cap_event_channel_opened_get_local_cid(packet));
2368                     if (gatt_client != NULL){
2369                         con_handle = l2cap_event_channel_opened_get_handle(packet);
2370                         hci_connection = hci_connection_for_handle(con_handle);
2371                         if (status == L2CAP_CONNECTION_RESPONSE_RESULT_REFUSED_RESOURCES){
2372                             if ((hci_connection != NULL) && hci_connection->att_server.incoming_connection_request) {
2373                                 log_info("Collision, retry in 100ms");
2374                                 gatt_client->state = P_W2_L2CAP_CONNECT;
2375                                 // set timer for retry
2376                                 btstack_run_loop_set_timer(&gatt_client->gc_timeout, GATT_CLIENT_COLLISION_BACKOFF_MS);
2377                                 btstack_run_loop_set_timer_handler(&gatt_client->gc_timeout, gatt_client_classic_retry);
2378                                 btstack_run_loop_add_timer(&gatt_client->gc_timeout);
2379                                 break;
2380                             }
2381                         }
2382                         // if status != 0, gatt_client will be discarded
2383                         gatt_client->state = P_READY;
2384                         gatt_client->con_handle = l2cap_event_channel_opened_get_handle(packet);
2385                         gatt_client->mtu = l2cap_event_channel_opened_get_remote_mtu(packet);
2386                         gatt_client_classic_handle_connected(gatt_client, status);
2387                     }
2388                     break;
2389                 case L2CAP_EVENT_CHANNEL_CLOSED:
2390                     gatt_client = gatt_client_get_context_for_l2cap_cid(l2cap_event_channel_closed_get_local_cid(packet));
2391                     if (gatt_client != NULL){
2392                         // discard gatt client object
2393                         gatt_client_classic_handle_disconnected(gatt_client);
2394                     }
2395                     break;
2396 #endif
2397                 case L2CAP_EVENT_CAN_SEND_NOW:
2398                     gatt_client_run();
2399                     break;
2400                     // att_server has negotiated the mtu for this connection, cache if context exists
2401                 case ATT_EVENT_MTU_EXCHANGE_COMPLETE:
2402                     if (size < 6u) break;
2403                     gatt_client = gatt_client_get_context_for_handle(handle);
2404                     if (gatt_client != NULL) {
2405                         gatt_client->mtu = little_endian_read_16(packet, 4);
2406                     }
2407                     break;
2408                 default:
2409                     break;
2410             }
2411             break;
2412 
2413         case ATT_DATA_PACKET:
2414             // special cases: notifications & indications motivate creating context
2415             switch (packet[0]) {
2416                 case ATT_HANDLE_VALUE_NOTIFICATION:
2417                 case ATT_HANDLE_VALUE_INDICATION:
2418                     gatt_client_provide_context_for_handle(handle, &gatt_client);
2419                     break;
2420                 default:
2421                     gatt_client = gatt_client_get_context_for_handle(handle);
2422                     break;
2423             }
2424 
2425             if (gatt_client != NULL) {
2426                 gatt_client_handle_att_response(gatt_client, packet, size);
2427                 gatt_client_run();
2428             }
2429             break;
2430 
2431 #ifdef ENABLE_GATT_OVER_CLASSIC
2432         case L2CAP_DATA_PACKET:
2433             gatt_client = gatt_client_get_context_for_l2cap_cid(handle);
2434             if (gatt_client != NULL){
2435                 gatt_client_handle_att_response(gatt_client, packet, size);
2436                 gatt_client_run();
2437             }
2438             break;
2439 #endif
2440 
2441         default:
2442             break;
2443     }
2444 }
2445 
2446 #ifdef ENABLE_LE_SIGNED_WRITE
2447 static void att_signed_write_handle_cmac_result(uint8_t hash[8]){
2448     btstack_linked_list_iterator_t it;
2449     btstack_linked_list_iterator_init(&it, &gatt_client_connections);
2450     while (btstack_linked_list_iterator_has_next(&it)){
2451         gatt_client_t * gatt_client = (gatt_client_t *) btstack_linked_list_iterator_next(&it);
2452         if (gatt_client->state == P_W4_CMAC_RESULT){
2453             // store result
2454             (void)memcpy(gatt_client->cmac, hash, 8);
2455             // reverse_64(hash, gatt_client->cmac);
2456             gatt_client->state = P_W2_SEND_SIGNED_WRITE;
2457             gatt_client_run();
2458             return;
2459         }
2460     }
2461 }
2462 
2463 uint8_t gatt_client_signed_write_without_response(btstack_packet_handler_t callback, hci_con_handle_t con_handle, uint16_t value_handle, uint16_t message_len, uint8_t * message){
2464     gatt_client_t * gatt_client;
2465     uint8_t status = gatt_client_provide_context_for_handle(con_handle, &gatt_client);
2466     if (status != ERROR_CODE_SUCCESS){
2467         return status;
2468     }
2469     if (is_ready(gatt_client) == 0){
2470         return GATT_CLIENT_IN_WRONG_STATE;
2471     }
2472 
2473     gatt_client->callback = callback;
2474     gatt_client->attribute_handle = value_handle;
2475     gatt_client->attribute_length = message_len;
2476     gatt_client->attribute_value = message;
2477     gatt_client->state = P_W4_IDENTITY_RESOLVING;
2478     gatt_client_run();
2479     return ERROR_CODE_SUCCESS;
2480 }
2481 #endif
2482 
2483 uint8_t gatt_client_discover_primary_services(btstack_packet_handler_t callback, hci_con_handle_t con_handle){
2484     gatt_client_t * gatt_client;
2485     uint8_t status = gatt_client_provide_context_for_request(con_handle, &gatt_client);
2486     if (status != ERROR_CODE_SUCCESS){
2487         return status;
2488     }
2489 
2490     gatt_client->callback = callback;
2491     gatt_client->start_group_handle = 0x0001;
2492     gatt_client->end_group_handle   = 0xffff;
2493     gatt_client->state = P_W2_SEND_SERVICE_QUERY;
2494     gatt_client->uuid16 = GATT_PRIMARY_SERVICE_UUID;
2495     gatt_client_run();
2496     return ERROR_CODE_SUCCESS;
2497 }
2498 
2499 uint8_t gatt_client_discover_secondary_services(btstack_packet_handler_t callback, hci_con_handle_t con_handle){
2500     gatt_client_t * gatt_client;
2501     uint8_t status = gatt_client_provide_context_for_request(con_handle, &gatt_client);
2502     if (status != ERROR_CODE_SUCCESS){
2503         return status;
2504     }
2505 
2506     gatt_client->callback = callback;
2507     gatt_client->start_group_handle = 0x0001;
2508     gatt_client->end_group_handle   = 0xffff;
2509     gatt_client->state = P_W2_SEND_SERVICE_QUERY;
2510     gatt_client->uuid16 = GATT_SECONDARY_SERVICE_UUID;
2511     gatt_client_run();
2512     return ERROR_CODE_SUCCESS;
2513 }
2514 
2515 uint8_t gatt_client_discover_primary_services_by_uuid16(btstack_packet_handler_t callback, hci_con_handle_t con_handle, uint16_t uuid16){
2516     gatt_client_t * gatt_client;
2517     uint8_t status = gatt_client_provide_context_for_request(con_handle, &gatt_client);
2518     if (status != ERROR_CODE_SUCCESS){
2519         return status;
2520     }
2521 
2522     gatt_client->callback = callback;
2523     gatt_client->start_group_handle = 0x0001;
2524     gatt_client->end_group_handle   = 0xffff;
2525     gatt_client->state = P_W2_SEND_SERVICE_WITH_UUID_QUERY;
2526     gatt_client->uuid16 = uuid16;
2527     uuid_add_bluetooth_prefix((uint8_t*) &(gatt_client->uuid128), gatt_client->uuid16);
2528     gatt_client_run();
2529     return ERROR_CODE_SUCCESS;
2530 }
2531 
2532 uint8_t gatt_client_discover_primary_services_by_uuid128(btstack_packet_handler_t callback, hci_con_handle_t con_handle, const uint8_t * uuid128){
2533     gatt_client_t * gatt_client;
2534     uint8_t status = gatt_client_provide_context_for_request(con_handle, &gatt_client);
2535     if (status != ERROR_CODE_SUCCESS){
2536         return status;
2537     }
2538 
2539     gatt_client->callback = callback;
2540     gatt_client->start_group_handle = 0x0001;
2541     gatt_client->end_group_handle   = 0xffff;
2542     gatt_client->uuid16 = 0;
2543     (void)memcpy(gatt_client->uuid128, uuid128, 16);
2544     gatt_client->state = P_W2_SEND_SERVICE_WITH_UUID_QUERY;
2545     gatt_client_run();
2546     return ERROR_CODE_SUCCESS;
2547 }
2548 
2549 uint8_t gatt_client_discover_characteristics_for_service(btstack_packet_handler_t callback, hci_con_handle_t con_handle, gatt_client_service_t * service){
2550     gatt_client_t * gatt_client;
2551     uint8_t status = gatt_client_provide_context_for_request(con_handle, &gatt_client);
2552     if (status != ERROR_CODE_SUCCESS){
2553         return status;
2554     }
2555 
2556     gatt_client->callback = callback;
2557     gatt_client->start_group_handle = service->start_group_handle;
2558     gatt_client->end_group_handle   = service->end_group_handle;
2559     gatt_client->filter_with_uuid = false;
2560     gatt_client->characteristic_start_handle = 0;
2561     gatt_client->state = P_W2_SEND_ALL_CHARACTERISTICS_OF_SERVICE_QUERY;
2562     gatt_client_run();
2563     return ERROR_CODE_SUCCESS;
2564 }
2565 
2566 uint8_t gatt_client_find_included_services_for_service(btstack_packet_handler_t callback, hci_con_handle_t con_handle, gatt_client_service_t * service){
2567     gatt_client_t * gatt_client;
2568     uint8_t status = gatt_client_provide_context_for_request(con_handle, &gatt_client);
2569     if (status != ERROR_CODE_SUCCESS){
2570         return status;
2571     }
2572 
2573     gatt_client->callback = callback;
2574     gatt_client->start_group_handle = service->start_group_handle;
2575     gatt_client->end_group_handle   = service->end_group_handle;
2576     gatt_client->state = P_W2_SEND_INCLUDED_SERVICE_QUERY;
2577 
2578     gatt_client_run();
2579     return ERROR_CODE_SUCCESS;
2580 }
2581 
2582 uint8_t gatt_client_discover_characteristics_for_handle_range_by_uuid16(btstack_packet_handler_t callback, hci_con_handle_t con_handle, uint16_t start_handle, uint16_t end_handle, uint16_t uuid16){
2583     gatt_client_t * gatt_client;
2584     uint8_t status = gatt_client_provide_context_for_request(con_handle, &gatt_client);
2585     if (status != ERROR_CODE_SUCCESS){
2586         return status;
2587     }
2588 
2589     gatt_client->callback = callback;
2590     gatt_client->start_group_handle = start_handle;
2591     gatt_client->end_group_handle   = end_handle;
2592     gatt_client->filter_with_uuid = true;
2593     gatt_client->uuid16 = uuid16;
2594     uuid_add_bluetooth_prefix((uint8_t*) &(gatt_client->uuid128), uuid16);
2595     gatt_client->characteristic_start_handle = 0;
2596     gatt_client->state = P_W2_SEND_CHARACTERISTIC_WITH_UUID_QUERY;
2597     gatt_client_run();
2598     return ERROR_CODE_SUCCESS;
2599 }
2600 
2601 uint8_t gatt_client_discover_characteristics_for_handle_range_by_uuid128(btstack_packet_handler_t callback, hci_con_handle_t con_handle, uint16_t start_handle, uint16_t end_handle, const uint8_t * uuid128){
2602     gatt_client_t * gatt_client;
2603     uint8_t status = gatt_client_provide_context_for_request(con_handle, &gatt_client);
2604     if (status != ERROR_CODE_SUCCESS){
2605         return status;
2606     }
2607 
2608     gatt_client->callback = callback;
2609     gatt_client->start_group_handle = start_handle;
2610     gatt_client->end_group_handle   = end_handle;
2611     gatt_client->filter_with_uuid = true;
2612     gatt_client->uuid16 = 0;
2613     (void)memcpy(gatt_client->uuid128, uuid128, 16);
2614     gatt_client->characteristic_start_handle = 0;
2615     gatt_client->state = P_W2_SEND_CHARACTERISTIC_WITH_UUID_QUERY;
2616     gatt_client_run();
2617     return ERROR_CODE_SUCCESS;
2618 }
2619 
2620 
2621 uint8_t gatt_client_discover_characteristics_for_service_by_uuid16(btstack_packet_handler_t callback, hci_con_handle_t con_handle, gatt_client_service_t * service, uint16_t uuid16){
2622     return gatt_client_discover_characteristics_for_handle_range_by_uuid16(callback, con_handle, service->start_group_handle, service->end_group_handle, uuid16);
2623 }
2624 
2625 uint8_t gatt_client_discover_characteristics_for_service_by_uuid128(btstack_packet_handler_t callback, hci_con_handle_t con_handle, gatt_client_service_t * service, const uint8_t * uuid128){
2626     return gatt_client_discover_characteristics_for_handle_range_by_uuid128(callback, con_handle, service->start_group_handle, service->end_group_handle, uuid128);
2627 }
2628 
2629 uint8_t gatt_client_discover_characteristic_descriptors(btstack_packet_handler_t callback, hci_con_handle_t con_handle, gatt_client_characteristic_t * characteristic){
2630     gatt_client_t * gatt_client;
2631     uint8_t status = gatt_client_provide_context_for_request(con_handle, &gatt_client);
2632     if (status != ERROR_CODE_SUCCESS){
2633         return status;
2634     }
2635 
2636     // check if there is space for characteristics descriptors
2637     if (characteristic->end_handle > characteristic->value_handle){
2638         gatt_client->callback = callback;
2639         gatt_client->start_group_handle = characteristic->value_handle + 1u;
2640         gatt_client->end_group_handle   = characteristic->end_handle;
2641         gatt_client->state = P_W2_SEND_ALL_CHARACTERISTIC_DESCRIPTORS_QUERY;
2642         gatt_client_run();
2643     } else {
2644         // schedule gatt complete event on next run loop iteration otherwise
2645         gatt_client->state = P_W2_EMIT_QUERY_COMPLETE_EVENT;
2646         gatt_client_deferred_event_emit.callback = gatt_client_emit_events;
2647         btstack_run_loop_execute_on_main_thread(&gatt_client_deferred_event_emit);
2648     }
2649     return ERROR_CODE_SUCCESS;
2650 }
2651 
2652 uint8_t gatt_client_read_value_of_characteristic_using_value_handle(btstack_packet_handler_t callback, hci_con_handle_t con_handle, uint16_t value_handle){
2653     gatt_client_t * gatt_client;
2654     uint8_t status = gatt_client_provide_context_for_request(con_handle, &gatt_client);
2655     if (status != ERROR_CODE_SUCCESS){
2656         return status;
2657     }
2658 
2659     gatt_client->callback = callback;
2660     gatt_client->attribute_handle = value_handle;
2661     gatt_client->attribute_offset = 0;
2662     gatt_client->state = P_W2_SEND_READ_CHARACTERISTIC_VALUE_QUERY;
2663     gatt_client_run();
2664     return ERROR_CODE_SUCCESS;
2665 }
2666 
2667 uint8_t gatt_client_read_value_of_characteristics_by_uuid16(btstack_packet_handler_t callback, hci_con_handle_t con_handle, uint16_t start_handle, uint16_t end_handle, uint16_t uuid16){
2668     gatt_client_t * gatt_client;
2669     uint8_t status = gatt_client_provide_context_for_request(con_handle, &gatt_client);
2670     if (status != ERROR_CODE_SUCCESS){
2671         return status;
2672     }
2673 
2674     gatt_client->callback = callback;
2675     gatt_client->start_group_handle = start_handle;
2676     gatt_client->end_group_handle = end_handle;
2677     gatt_client->query_start_handle = start_handle;
2678     gatt_client->query_end_handle = end_handle;
2679     gatt_client->uuid16 = uuid16;
2680     uuid_add_bluetooth_prefix((uint8_t*) &(gatt_client->uuid128), uuid16);
2681     gatt_client->state = P_W2_SEND_READ_BY_TYPE_REQUEST;
2682     gatt_client_run();
2683     return ERROR_CODE_SUCCESS;
2684 }
2685 
2686 uint8_t gatt_client_read_value_of_characteristics_by_uuid128(btstack_packet_handler_t callback, hci_con_handle_t con_handle, uint16_t start_handle, uint16_t end_handle, const uint8_t * uuid128){
2687     gatt_client_t * gatt_client;
2688     uint8_t status = gatt_client_provide_context_for_request(con_handle, &gatt_client);
2689     if (status != ERROR_CODE_SUCCESS){
2690         return status;
2691     }
2692 
2693     gatt_client->callback = callback;
2694     gatt_client->start_group_handle = start_handle;
2695     gatt_client->end_group_handle = end_handle;
2696     gatt_client->query_start_handle = start_handle;
2697     gatt_client->query_end_handle = end_handle;
2698     gatt_client->uuid16 = 0;
2699     (void)memcpy(gatt_client->uuid128, uuid128, 16);
2700     gatt_client->state = P_W2_SEND_READ_BY_TYPE_REQUEST;
2701     gatt_client_run();
2702     return ERROR_CODE_SUCCESS;
2703 }
2704 
2705 
2706 uint8_t gatt_client_read_value_of_characteristic(btstack_packet_handler_t callback, hci_con_handle_t con_handle, gatt_client_characteristic_t * characteristic){
2707     return gatt_client_read_value_of_characteristic_using_value_handle(callback, con_handle, characteristic->value_handle);
2708 }
2709 
2710 uint8_t gatt_client_read_long_value_of_characteristic_using_value_handle_with_offset(btstack_packet_handler_t callback, hci_con_handle_t con_handle, uint16_t value_handle, uint16_t offset){
2711     gatt_client_t * gatt_client;
2712     uint8_t status = gatt_client_provide_context_for_request(con_handle, &gatt_client);
2713     if (status != ERROR_CODE_SUCCESS){
2714         return status;
2715     }
2716 
2717     gatt_client->callback = callback;
2718     gatt_client->attribute_handle = value_handle;
2719     gatt_client->attribute_offset = offset;
2720     gatt_client->state = P_W2_SEND_READ_BLOB_QUERY;
2721     gatt_client_run();
2722     return ERROR_CODE_SUCCESS;
2723 }
2724 
2725 uint8_t gatt_client_read_long_value_of_characteristic_using_value_handle(btstack_packet_handler_t callback, hci_con_handle_t con_handle, uint16_t value_handle){
2726     return gatt_client_read_long_value_of_characteristic_using_value_handle_with_offset(callback, con_handle, value_handle, 0);
2727 }
2728 
2729 uint8_t gatt_client_read_long_value_of_characteristic(btstack_packet_handler_t callback, hci_con_handle_t con_handle, gatt_client_characteristic_t * characteristic){
2730     return gatt_client_read_long_value_of_characteristic_using_value_handle(callback, con_handle, characteristic->value_handle);
2731 }
2732 
2733 static uint8_t gatt_client_read_multiple_characteristic_values_with_state(btstack_packet_handler_t callback, hci_con_handle_t con_handle, int num_value_handles, uint16_t * value_handles, gatt_client_state_t state){
2734     gatt_client_t * gatt_client;
2735     uint8_t status = gatt_client_provide_context_for_request(con_handle, &gatt_client);
2736     if (status != ERROR_CODE_SUCCESS){
2737         return status;
2738     }
2739 
2740 #ifdef ENABLE_GATT_OVER_EATT
2741     if (state == P_W2_SEND_READ_MULTIPLE_VARIABLE_REQUEST){
2742         if (gatt_client->bearer_type != ATT_BEARER_ENHANCED_LE){
2743             return ERROR_CODE_COMMAND_DISALLOWED;
2744         }
2745     }
2746 #endif
2747 
2748     gatt_client->callback = callback;
2749     gatt_client->read_multiple_handle_count = num_value_handles;
2750     gatt_client->read_multiple_handles = value_handles;
2751     gatt_client->state = state;
2752     gatt_client_run();
2753     return ERROR_CODE_SUCCESS;
2754 }
2755 
2756 uint8_t gatt_client_read_multiple_characteristic_values(btstack_packet_handler_t callback, hci_con_handle_t con_handle, int num_value_handles, uint16_t * value_handles){
2757     return gatt_client_read_multiple_characteristic_values_with_state(callback, con_handle, num_value_handles, value_handles, P_W2_SEND_READ_MULTIPLE_REQUEST);
2758 }
2759 
2760 #ifdef ENABLE_GATT_OVER_EATT
2761 uint8_t gatt_client_read_multiple_variable_characteristic_values(btstack_packet_handler_t callback, hci_con_handle_t con_handle, int num_value_handles, uint16_t * value_handles){
2762     return gatt_client_read_multiple_characteristic_values_with_state(callback, con_handle, num_value_handles, value_handles, P_W2_SEND_READ_MULTIPLE_VARIABLE_REQUEST);
2763 }
2764 #endif
2765 
2766 uint8_t gatt_client_write_value_of_characteristic_without_response(hci_con_handle_t con_handle, uint16_t value_handle, uint16_t value_length, uint8_t * value){
2767     gatt_client_t * gatt_client;
2768     uint8_t status = gatt_client_provide_context_for_handle(con_handle, &gatt_client);
2769     if (status != ERROR_CODE_SUCCESS){
2770         return status;
2771     }
2772 
2773     if (value_length > (gatt_client->mtu - 3u)) return GATT_CLIENT_VALUE_TOO_LONG;
2774     if (!att_dispatch_client_can_send_now(gatt_client->con_handle)) return GATT_CLIENT_BUSY;
2775 
2776     return att_write_request(gatt_client, ATT_WRITE_COMMAND, value_handle, value_length, value);
2777 }
2778 
2779 uint8_t gatt_client_write_value_of_characteristic(btstack_packet_handler_t callback, hci_con_handle_t con_handle, uint16_t value_handle, uint16_t value_length, uint8_t * value){
2780     gatt_client_t * gatt_client;
2781     uint8_t status = gatt_client_provide_context_for_request(con_handle, &gatt_client);
2782     if (status != ERROR_CODE_SUCCESS){
2783         return status;
2784     }
2785 
2786     gatt_client->callback = callback;
2787     gatt_client->attribute_handle = value_handle;
2788     gatt_client->attribute_length = value_length;
2789     gatt_client->attribute_value = value;
2790     gatt_client->state = P_W2_SEND_WRITE_CHARACTERISTIC_VALUE;
2791     gatt_client_run();
2792     return ERROR_CODE_SUCCESS;
2793 }
2794 
2795 uint8_t gatt_client_write_long_value_of_characteristic_with_offset(btstack_packet_handler_t callback, hci_con_handle_t con_handle, uint16_t value_handle, uint16_t offset, uint16_t value_length, uint8_t * value){
2796     gatt_client_t * gatt_client;
2797     uint8_t status = gatt_client_provide_context_for_request(con_handle, &gatt_client);
2798     if (status != ERROR_CODE_SUCCESS){
2799         return status;
2800     }
2801 
2802     gatt_client->callback = callback;
2803     gatt_client->attribute_handle = value_handle;
2804     gatt_client->attribute_length = value_length;
2805     gatt_client->attribute_offset = offset;
2806     gatt_client->attribute_value = value;
2807     gatt_client->state = P_W2_PREPARE_WRITE;
2808     gatt_client_run();
2809     return ERROR_CODE_SUCCESS;
2810 }
2811 
2812 uint8_t gatt_client_write_long_value_of_characteristic(btstack_packet_handler_t callback, hci_con_handle_t con_handle, uint16_t value_handle, uint16_t value_length, uint8_t * value){
2813     return gatt_client_write_long_value_of_characteristic_with_offset(callback, con_handle, value_handle, 0, value_length, value);
2814 }
2815 
2816 uint8_t gatt_client_reliable_write_long_value_of_characteristic(btstack_packet_handler_t callback, hci_con_handle_t con_handle, uint16_t value_handle, uint16_t value_length, uint8_t * value){
2817     gatt_client_t * gatt_client;
2818     uint8_t status = gatt_client_provide_context_for_request(con_handle, &gatt_client);
2819     if (status != ERROR_CODE_SUCCESS){
2820         return status;
2821     }
2822 
2823     gatt_client->callback = callback;
2824     gatt_client->attribute_handle = value_handle;
2825     gatt_client->attribute_length = value_length;
2826     gatt_client->attribute_offset = 0;
2827     gatt_client->attribute_value = value;
2828     gatt_client->state = P_W2_PREPARE_RELIABLE_WRITE;
2829     gatt_client_run();
2830     return ERROR_CODE_SUCCESS;
2831 }
2832 
2833 uint8_t gatt_client_write_client_characteristic_configuration(btstack_packet_handler_t callback, hci_con_handle_t con_handle, gatt_client_characteristic_t * characteristic, uint16_t configuration){
2834     gatt_client_t * gatt_client;
2835     uint8_t status = gatt_client_provide_context_for_request(con_handle, &gatt_client);
2836     if (status != ERROR_CODE_SUCCESS){
2837         return status;
2838     }
2839 
2840     if (configuration > 3){
2841         return ERROR_CODE_UNSUPPORTED_FEATURE_OR_PARAMETER_VALUE;
2842     }
2843 
2844     if ( (configuration & GATT_CLIENT_CHARACTERISTICS_CONFIGURATION_NOTIFICATION) &&
2845         ((characteristic->properties & ATT_PROPERTY_NOTIFY) == 0u)) {
2846         log_info("gatt_client_write_client_characteristic_configuration: GATT_CLIENT_CHARACTERISTIC_NOTIFICATION_NOT_SUPPORTED");
2847         return GATT_CLIENT_CHARACTERISTIC_NOTIFICATION_NOT_SUPPORTED;
2848     } else if ( (configuration & GATT_CLIENT_CHARACTERISTICS_CONFIGURATION_INDICATION) &&
2849                ((characteristic->properties & ATT_PROPERTY_INDICATE) == 0u)){
2850         log_info("gatt_client_write_client_characteristic_configuration: GATT_CLIENT_CHARACTERISTIC_INDICATION_NOT_SUPPORTED");
2851         return GATT_CLIENT_CHARACTERISTIC_INDICATION_NOT_SUPPORTED;
2852     }
2853 
2854     gatt_client->callback = callback;
2855     gatt_client->start_group_handle = characteristic->value_handle;
2856     gatt_client->end_group_handle = characteristic->end_handle;
2857     little_endian_store_16(gatt_client->client_characteristic_configuration_value, 0, configuration);
2858 
2859 #ifdef ENABLE_GATT_FIND_INFORMATION_FOR_CCC_DISCOVERY
2860     gatt_client->gatt_client_state = P_W2_SEND_FIND_CLIENT_CHARACTERISTIC_CONFIGURATION_QUERY;
2861 #else
2862     gatt_client->state = P_W2_SEND_READ_CLIENT_CHARACTERISTIC_CONFIGURATION_QUERY;
2863 #endif
2864     gatt_client_run();
2865     return ERROR_CODE_SUCCESS;
2866 }
2867 
2868 uint8_t gatt_client_read_characteristic_descriptor_using_descriptor_handle(btstack_packet_handler_t callback, hci_con_handle_t con_handle, uint16_t descriptor_handle){
2869     gatt_client_t * gatt_client;
2870     uint8_t status = gatt_client_provide_context_for_request(con_handle, &gatt_client);
2871     if (status != ERROR_CODE_SUCCESS){
2872         return status;
2873     }
2874 
2875     gatt_client->callback = callback;
2876     gatt_client->attribute_handle = descriptor_handle;
2877 
2878     gatt_client->state = P_W2_SEND_READ_CHARACTERISTIC_DESCRIPTOR_QUERY;
2879     gatt_client_run();
2880     return ERROR_CODE_SUCCESS;
2881 }
2882 
2883 uint8_t gatt_client_read_characteristic_descriptor(btstack_packet_handler_t callback, hci_con_handle_t con_handle, gatt_client_characteristic_descriptor_t * descriptor){
2884     return gatt_client_read_characteristic_descriptor_using_descriptor_handle(callback, con_handle, descriptor->handle);
2885 }
2886 
2887 uint8_t gatt_client_read_long_characteristic_descriptor_using_descriptor_handle_with_offset(btstack_packet_handler_t callback, hci_con_handle_t con_handle, uint16_t descriptor_handle, uint16_t offset){
2888     gatt_client_t * gatt_client;
2889     uint8_t status = gatt_client_provide_context_for_request(con_handle, &gatt_client);
2890     if (status != ERROR_CODE_SUCCESS){
2891         return status;
2892     }
2893 
2894     gatt_client->callback = callback;
2895     gatt_client->attribute_handle = descriptor_handle;
2896     gatt_client->attribute_offset = offset;
2897     gatt_client->state = P_W2_SEND_READ_BLOB_CHARACTERISTIC_DESCRIPTOR_QUERY;
2898     gatt_client_run();
2899     return ERROR_CODE_SUCCESS;
2900 }
2901 
2902 uint8_t gatt_client_read_long_characteristic_descriptor_using_descriptor_handle(btstack_packet_handler_t callback, hci_con_handle_t con_handle, uint16_t descriptor_handle){
2903     return gatt_client_read_long_characteristic_descriptor_using_descriptor_handle_with_offset(callback, con_handle, descriptor_handle, 0);
2904 }
2905 
2906 uint8_t gatt_client_read_long_characteristic_descriptor(btstack_packet_handler_t callback, hci_con_handle_t con_handle, gatt_client_characteristic_descriptor_t * descriptor){
2907     return gatt_client_read_long_characteristic_descriptor_using_descriptor_handle(callback, con_handle, descriptor->handle);
2908 }
2909 
2910 uint8_t gatt_client_write_characteristic_descriptor_using_descriptor_handle(btstack_packet_handler_t callback, hci_con_handle_t con_handle, uint16_t descriptor_handle, uint16_t value_length, uint8_t * value){
2911     gatt_client_t * gatt_client;
2912     uint8_t status = gatt_client_provide_context_for_request(con_handle, &gatt_client);
2913     if (status != ERROR_CODE_SUCCESS){
2914         return status;
2915     }
2916 
2917     gatt_client->callback = callback;
2918     gatt_client->attribute_handle = descriptor_handle;
2919     gatt_client->attribute_length = value_length;
2920     gatt_client->attribute_offset = 0;
2921     gatt_client->attribute_value = value;
2922     gatt_client->state = P_W2_SEND_WRITE_CHARACTERISTIC_DESCRIPTOR;
2923     gatt_client_run();
2924     return ERROR_CODE_SUCCESS;
2925 }
2926 
2927 uint8_t gatt_client_write_characteristic_descriptor(btstack_packet_handler_t callback, hci_con_handle_t con_handle, gatt_client_characteristic_descriptor_t * descriptor, uint16_t value_length, uint8_t * value){
2928     return gatt_client_write_characteristic_descriptor_using_descriptor_handle(callback, con_handle, descriptor->handle, value_length, value);
2929 }
2930 
2931 uint8_t gatt_client_write_long_characteristic_descriptor_using_descriptor_handle_with_offset(btstack_packet_handler_t callback, hci_con_handle_t con_handle, uint16_t descriptor_handle, uint16_t offset, uint16_t value_length, uint8_t * value){
2932     gatt_client_t * gatt_client;
2933     uint8_t status = gatt_client_provide_context_for_request(con_handle, &gatt_client);
2934     if (status != ERROR_CODE_SUCCESS){
2935         return status;
2936     }
2937 
2938     gatt_client->callback = callback;
2939     gatt_client->attribute_handle = descriptor_handle;
2940     gatt_client->attribute_length = value_length;
2941     gatt_client->attribute_offset = offset;
2942     gatt_client->attribute_value = value;
2943     gatt_client->state = P_W2_PREPARE_WRITE_CHARACTERISTIC_DESCRIPTOR;
2944     gatt_client_run();
2945     return ERROR_CODE_SUCCESS;
2946 }
2947 
2948 uint8_t gatt_client_write_long_characteristic_descriptor_using_descriptor_handle(btstack_packet_handler_t callback, hci_con_handle_t con_handle, uint16_t descriptor_handle, uint16_t value_length, uint8_t * value){
2949     return gatt_client_write_long_characteristic_descriptor_using_descriptor_handle_with_offset(callback, con_handle, descriptor_handle, 0, value_length, value);
2950 }
2951 
2952 uint8_t gatt_client_write_long_characteristic_descriptor(btstack_packet_handler_t callback, hci_con_handle_t con_handle, gatt_client_characteristic_descriptor_t * descriptor, uint16_t value_length, uint8_t * value){
2953     return gatt_client_write_long_characteristic_descriptor_using_descriptor_handle(callback, con_handle, descriptor->handle, value_length, value);
2954 }
2955 
2956 /**
2957  * @brief -> gatt complete event
2958  */
2959 uint8_t gatt_client_prepare_write(btstack_packet_handler_t callback, hci_con_handle_t con_handle, uint16_t attribute_handle, uint16_t offset, uint16_t value_length, uint8_t * value){
2960     gatt_client_t * gatt_client;
2961     uint8_t status = gatt_client_provide_context_for_request(con_handle, &gatt_client);
2962     if (status != ERROR_CODE_SUCCESS){
2963         return status;
2964     }
2965 
2966     gatt_client->callback = callback;
2967     gatt_client->attribute_handle = attribute_handle;
2968     gatt_client->attribute_length = value_length;
2969     gatt_client->attribute_offset = offset;
2970     gatt_client->attribute_value = value;
2971     gatt_client->state = P_W2_PREPARE_WRITE_SINGLE;
2972     gatt_client_run();
2973     return ERROR_CODE_SUCCESS;
2974 }
2975 
2976 /**
2977  * @brief -> gatt complete event
2978  */
2979 uint8_t gatt_client_execute_write(btstack_packet_handler_t callback, hci_con_handle_t con_handle){
2980     gatt_client_t * gatt_client;
2981     uint8_t status = gatt_client_provide_context_for_request(con_handle, &gatt_client);
2982     if (status != ERROR_CODE_SUCCESS){
2983         return status;
2984     }
2985 
2986     gatt_client->callback = callback;
2987     gatt_client->state = P_W2_EXECUTE_PREPARED_WRITE;
2988     gatt_client_run();
2989     return ERROR_CODE_SUCCESS;
2990 }
2991 
2992 /**
2993  * @brief -> gatt complete event
2994  */
2995 uint8_t gatt_client_cancel_write(btstack_packet_handler_t callback, hci_con_handle_t con_handle){
2996     gatt_client_t * gatt_client;
2997     uint8_t status = gatt_client_provide_context_for_request(con_handle, &gatt_client);
2998     if (status != ERROR_CODE_SUCCESS){
2999         return status;
3000     }
3001 
3002     gatt_client->callback = callback;
3003     gatt_client->state = P_W2_CANCEL_PREPARED_WRITE;
3004     gatt_client_run();
3005     return ERROR_CODE_SUCCESS;
3006 }
3007 
3008 void gatt_client_deserialize_service(const uint8_t *packet, int offset, gatt_client_service_t * service){
3009     service->start_group_handle = little_endian_read_16(packet, offset);
3010     service->end_group_handle = little_endian_read_16(packet, offset + 2);
3011     reverse_128(&packet[offset + 4], service->uuid128);
3012     if (uuid_has_bluetooth_prefix(service->uuid128)){
3013         service->uuid16 = big_endian_read_32(service->uuid128, 0);
3014     } else {
3015         service->uuid16 = 0;
3016     }
3017 }
3018 
3019 void gatt_client_deserialize_characteristic(const uint8_t * packet, int offset, gatt_client_characteristic_t * characteristic){
3020     characteristic->start_handle = little_endian_read_16(packet, offset);
3021     characteristic->value_handle = little_endian_read_16(packet, offset + 2);
3022     characteristic->end_handle = little_endian_read_16(packet, offset + 4);
3023     characteristic->properties = little_endian_read_16(packet, offset + 6);
3024     reverse_128(&packet[offset+8], characteristic->uuid128);
3025     if (uuid_has_bluetooth_prefix(characteristic->uuid128)){
3026         characteristic->uuid16 = big_endian_read_32(characteristic->uuid128, 0);
3027     } else {
3028         characteristic->uuid16 = 0;
3029     }
3030 }
3031 
3032 void gatt_client_deserialize_characteristic_descriptor(const uint8_t * packet, int offset, gatt_client_characteristic_descriptor_t * descriptor){
3033     descriptor->handle = little_endian_read_16(packet, offset);
3034     reverse_128(&packet[offset+2], descriptor->uuid128);
3035     if (uuid_has_bluetooth_prefix(descriptor->uuid128)){
3036         descriptor->uuid16 = big_endian_read_32(descriptor->uuid128, 0);
3037     } else {
3038         descriptor->uuid16 = 0;
3039     }
3040 }
3041 
3042 void gatt_client_send_mtu_negotiation(btstack_packet_handler_t callback, hci_con_handle_t con_handle){
3043     gatt_client_t * gatt_client;
3044     uint8_t status = gatt_client_provide_context_for_handle(con_handle, &gatt_client);
3045     if (status != ERROR_CODE_SUCCESS){
3046         return;
3047     }
3048     if (gatt_client->mtu_state == MTU_AUTO_EXCHANGE_DISABLED){
3049         gatt_client->callback = callback;
3050         gatt_client->mtu_state = SEND_MTU_EXCHANGE;
3051         gatt_client_run();
3052     }
3053 }
3054 
3055 uint8_t gatt_client_request_to_write_without_response(btstack_context_callback_registration_t * callback_registration, hci_con_handle_t con_handle){
3056     gatt_client_t * gatt_client;
3057     uint8_t status = gatt_client_provide_context_for_handle(con_handle, &gatt_client);
3058     if (status != ERROR_CODE_SUCCESS){
3059         return status;
3060     }
3061     bool added = btstack_linked_list_add_tail(&gatt_client->write_without_response_requests, (btstack_linked_item_t*) callback_registration);
3062     if (added == false){
3063         return ERROR_CODE_COMMAND_DISALLOWED;
3064     } else {
3065         att_dispatch_client_request_can_send_now_event(gatt_client->con_handle);
3066         return ERROR_CODE_SUCCESS;
3067     }
3068 }
3069 
3070 uint8_t gatt_client_request_to_send_gatt_query(btstack_context_callback_registration_t * callback_registration, hci_con_handle_t con_handle){
3071     gatt_client_t * gatt_client;
3072     uint8_t status = gatt_client_provide_context_for_handle(con_handle, &gatt_client);
3073     if (status != ERROR_CODE_SUCCESS){
3074         return status;
3075     }
3076     bool added = btstack_linked_list_add_tail(&gatt_client->query_requests, (btstack_linked_item_t*) callback_registration);
3077     if (added == false){
3078         return ERROR_CODE_COMMAND_DISALLOWED;
3079     } else {
3080         gatt_client_notify_can_send_query(gatt_client);
3081         return ERROR_CODE_SUCCESS;
3082     }
3083 }
3084 
3085 uint8_t gatt_client_remove_gatt_query(btstack_context_callback_registration_t * callback_registration, hci_con_handle_t con_handle){
3086     gatt_client_t * gatt_client;
3087     uint8_t status = gatt_client_provide_context_for_handle(con_handle, &gatt_client);
3088     if (status != ERROR_CODE_SUCCESS){
3089         return status;
3090     }
3091     (void)btstack_linked_list_remove(&gatt_client->query_requests, (btstack_linked_item_t*) callback_registration);
3092     return ERROR_CODE_SUCCESS;
3093 }
3094 
3095 uint8_t gatt_client_request_can_write_without_response_event(btstack_packet_handler_t callback, hci_con_handle_t con_handle){
3096     gatt_client_t * gatt_client;
3097     uint8_t status = gatt_client_provide_context_for_handle(con_handle, &gatt_client);
3098     if (status != ERROR_CODE_SUCCESS){
3099         return status;
3100     }
3101     if (gatt_client->write_without_response_callback != NULL){
3102         return GATT_CLIENT_IN_WRONG_STATE;
3103     }
3104     gatt_client->write_without_response_callback = callback;
3105     att_dispatch_client_request_can_send_now_event(gatt_client->con_handle);
3106     return ERROR_CODE_SUCCESS;
3107 }
3108 
3109 #ifdef ENABLE_GATT_CLIENT_SERVICE_CHANGED
3110 void gatt_client_add_service_changed_handler(btstack_packet_callback_registration_t * callback) {
3111     btstack_linked_list_add_tail(&gatt_client_service_changed_handler, (btstack_linked_item_t*) callback);
3112 }
3113 
3114 void gatt_client_remove_service_changed_handler(btstack_packet_callback_registration_t * callback){
3115     btstack_linked_list_remove(&gatt_client_service_changed_handler, (btstack_linked_item_t*) callback);
3116 }
3117 #endif
3118 
3119 #if defined(ENABLE_GATT_OVER_CLASSIC) || defined(ENABLE_GATT_OVER_EATT)
3120 
3121 #include "hci_event.h"
3122 
3123 static const hci_event_t gatt_client_connected = {
3124         GATT_EVENT_CONNECTED, 0, "11BH"
3125 };
3126 
3127 static const hci_event_t gatt_client_disconnected = {
3128         GATT_EVENT_DISCONNECTED, 0, "H"
3129 };
3130 
3131 static void
3132 gatt_client_emit_connected(btstack_packet_handler_t callback, uint8_t status, bd_addr_type_t addr_type, bd_addr_t addr,
3133                            hci_con_handle_t con_handle) {
3134     uint8_t buffer[20];
3135     uint16_t len = hci_event_create_from_template_and_arguments(buffer, sizeof(buffer), &gatt_client_connected, status, addr, con_handle);
3136     (*callback)(HCI_EVENT_PACKET, 0, buffer, len);
3137 }
3138 
3139 #endif
3140 
3141 #ifdef ENABLE_GATT_OVER_CLASSIC
3142 
3143 #include "bluetooth_psm.h"
3144 
3145 // single active SDP query
3146 static gatt_client_t * gatt_client_classic_active_sdp_query;
3147 
3148 // macos protocol descriptor list requires 16 bytes
3149 static uint8_t gatt_client_classic_sdp_buffer[32];
3150 
3151 
3152 static gatt_client_t * gatt_client_get_context_for_classic_addr(bd_addr_t addr){
3153     btstack_linked_item_t *it;
3154     for (it = (btstack_linked_item_t *) gatt_client_connections; it != NULL; it = it->next){
3155         gatt_client_t * gatt_client = (gatt_client_t *) it;
3156         if (memcmp(gatt_client->addr, addr, 6) == 0){
3157             return gatt_client;
3158         }
3159     }
3160     return NULL;
3161 }
3162 
3163 static gatt_client_t * gatt_client_get_context_for_l2cap_cid(uint16_t l2cap_cid){
3164     btstack_linked_item_t *it;
3165     for (it = (btstack_linked_item_t *) gatt_client_connections; it != NULL; it = it->next){
3166         gatt_client_t * gatt_client = (gatt_client_t *) it;
3167         if (gatt_client->l2cap_cid == l2cap_cid){
3168             return gatt_client;
3169         }
3170     }
3171     return NULL;
3172 }
3173 
3174 static void gatt_client_classic_handle_connected(gatt_client_t * gatt_client, uint8_t status){
3175     // cache peer information
3176     bd_addr_t addr;
3177     // cppcheck-suppress uninitvar ; addr is reported as uninitialized although it's the destination of the memcpy
3178     memcpy(addr, gatt_client->addr, 6);
3179     bd_addr_type_t addr_type = gatt_client->addr_type;
3180     gatt_client->addr_type = BD_ADDR_TYPE_ACL;
3181     hci_con_handle_t con_handle = gatt_client->con_handle;
3182     btstack_packet_handler_t callback = gatt_client->callback;
3183 
3184     if (status != ERROR_CODE_SUCCESS){
3185         btstack_linked_list_remove(&gatt_client_connections, (btstack_linked_item_t *) gatt_client);
3186         btstack_memory_gatt_client_free(gatt_client);
3187     }
3188 
3189     gatt_client_emit_connected(callback, status, addr_type, addr, con_handle);
3190 }
3191 
3192 static void gatt_client_classic_retry(btstack_timer_source_t * ts){
3193     gatt_client_t * gatt_client = gatt_client_for_timer(ts);
3194     if (gatt_client != NULL){
3195         gatt_client->state = P_W4_L2CAP_CONNECTION;
3196         att_dispatch_classic_connect(gatt_client->addr, gatt_client->l2cap_psm, &gatt_client->l2cap_cid);
3197     }
3198 }
3199 
3200 static void gatt_client_classic_handle_disconnected(gatt_client_t * gatt_client){
3201 
3202     gatt_client_report_error_if_pending(gatt_client, ATT_ERROR_HCI_DISCONNECT_RECEIVED);
3203     gatt_client_timeout_stop(gatt_client);
3204 
3205     hci_con_handle_t con_handle = gatt_client->con_handle;
3206     btstack_packet_handler_t callback = gatt_client->callback;
3207     btstack_linked_list_remove(&gatt_client_connections, (btstack_linked_item_t *) gatt_client);
3208     btstack_memory_gatt_client_free(gatt_client);
3209 
3210     uint8_t buffer[20];
3211     uint16_t len = hci_event_create_from_template_and_arguments(buffer, sizeof(buffer), &gatt_client_disconnected, con_handle);
3212     (*callback)(HCI_EVENT_PACKET, 0, buffer, len);
3213 }
3214 
3215 static void gatt_client_handle_sdp_client_query_attribute_value(gatt_client_t * connection, uint8_t *packet){
3216     des_iterator_t des_list_it;
3217     des_iterator_t prot_it;
3218 
3219     if (sdp_event_query_attribute_byte_get_attribute_length(packet) <= sizeof(gatt_client_classic_sdp_buffer)) {
3220         gatt_client_classic_sdp_buffer[sdp_event_query_attribute_byte_get_data_offset(packet)] = sdp_event_query_attribute_byte_get_data(packet);
3221         if ((uint16_t)(sdp_event_query_attribute_byte_get_data_offset(packet)+1) == sdp_event_query_attribute_byte_get_attribute_length(packet)) {
3222             switch(sdp_event_query_attribute_byte_get_attribute_id(packet)) {
3223                 case BLUETOOTH_ATTRIBUTE_PROTOCOL_DESCRIPTOR_LIST:
3224                     for (des_iterator_init(&des_list_it, gatt_client_classic_sdp_buffer); des_iterator_has_more(&des_list_it); des_iterator_next(&des_list_it)) {
3225                         uint8_t       *des_element;
3226                         uint8_t       *element;
3227                         uint32_t       uuid;
3228 
3229                         if (des_iterator_get_type(&des_list_it) != DE_DES) continue;
3230 
3231                         des_element = des_iterator_get_element(&des_list_it);
3232                         des_iterator_init(&prot_it, des_element);
3233                         element = des_iterator_get_element(&prot_it);
3234 
3235                         if (de_get_element_type(element) != DE_UUID) continue;
3236 
3237                         uuid = de_get_uuid32(element);
3238                         des_iterator_next(&prot_it);
3239                         // we assume that the even if there are both roles supported, remote device uses the same psm and avdtp version for both
3240                         switch (uuid){
3241                             case BLUETOOTH_PROTOCOL_L2CAP:
3242                                 if (!des_iterator_has_more(&prot_it)) continue;
3243                                 de_element_get_uint16(des_iterator_get_element(&prot_it), &connection->l2cap_psm);
3244                                 break;
3245                             default:
3246                                 break;
3247                         }
3248                     }
3249                     break;
3250 
3251                 default:
3252                     break;
3253             }
3254         }
3255     }
3256 }
3257 
3258 static void gatt_client_classic_sdp_handler(uint8_t packet_type, uint16_t handle, uint8_t *packet, uint16_t size){
3259     gatt_client_t * gatt_client = gatt_client_classic_active_sdp_query;
3260     btstack_assert(gatt_client != NULL);
3261     uint8_t status;
3262 
3263     // TODO: handle sdp events, get l2cap psm
3264     switch (hci_event_packet_get_type(packet)){
3265         case SDP_EVENT_QUERY_ATTRIBUTE_VALUE:
3266             gatt_client_handle_sdp_client_query_attribute_value(gatt_client, packet);
3267             // TODO:
3268             return;
3269         case SDP_EVENT_QUERY_COMPLETE:
3270             status = sdp_event_query_complete_get_status(packet);
3271             gatt_client_classic_active_sdp_query = NULL;
3272             log_info("l2cap psm: %0x, status %02x", gatt_client->l2cap_psm, status);
3273             if (status != ERROR_CODE_SUCCESS) break;
3274             if (gatt_client->l2cap_psm == 0) {
3275                 status = SDP_SERVICE_NOT_FOUND;
3276                 break;
3277             }
3278             break;
3279         default:
3280             btstack_assert(false);
3281             return;
3282     }
3283 
3284     // done
3285     if (status == ERROR_CODE_SUCCESS){
3286         gatt_client->state = P_W4_L2CAP_CONNECTION;
3287         status = att_dispatch_classic_connect(gatt_client->addr, gatt_client->l2cap_psm, &gatt_client->l2cap_cid);
3288     }
3289     if (status != ERROR_CODE_SUCCESS) {
3290         gatt_client_classic_handle_connected(gatt_client, status);
3291     }
3292 }
3293 
3294 static void gatt_client_classic_sdp_start(void * context){
3295     gatt_client_classic_active_sdp_query = (gatt_client_t *) context;
3296     gatt_client_classic_active_sdp_query->state = P_W4_SDP_QUERY;
3297     sdp_client_query_uuid16(gatt_client_classic_sdp_handler, gatt_client_classic_active_sdp_query->addr, ORG_BLUETOOTH_SERVICE_GENERIC_ATTRIBUTE);
3298 }
3299 
3300 static void gatt_client_classic_emit_connected(void * context){
3301     gatt_client_t * gatt_client = (gatt_client_t *) context;
3302     gatt_client->state = P_READY;
3303     gatt_client_emit_connected(gatt_client->callback, ERROR_CODE_SUCCESS, gatt_client->addr_type, gatt_client->addr, gatt_client->con_handle);
3304 }
3305 
3306 uint8_t gatt_client_classic_connect(btstack_packet_handler_t callback, bd_addr_t addr){
3307     gatt_client_t * gatt_client = gatt_client_get_context_for_classic_addr(addr);
3308     if (gatt_client != NULL){
3309         return ERROR_CODE_ACL_CONNECTION_ALREADY_EXISTS;
3310     }
3311     gatt_client = btstack_memory_gatt_client_get();
3312     if (gatt_client == NULL){
3313         return ERROR_CODE_MEMORY_CAPACITY_EXCEEDED;
3314     }
3315     // init state
3316     gatt_client->bearer_type = ATT_BEARER_UNENHANCED_CLASSIC;
3317     gatt_client->con_handle = HCI_CON_HANDLE_INVALID;
3318     memcpy(gatt_client->addr, addr, 6);
3319     gatt_client->addr_type = BD_ADDR_TYPE_ACL;
3320     gatt_client->mtu = ATT_DEFAULT_MTU;
3321     gatt_client->security_level = LEVEL_0;
3322     gatt_client->mtu_state = MTU_AUTO_EXCHANGE_DISABLED;
3323     gatt_client->callback = callback;
3324 #ifdef ENABLE_GATT_OVER_EATT
3325     gatt_client->eatt_state = GATT_CLIENT_EATT_IDLE;
3326 #endif
3327     btstack_linked_list_add(&gatt_client_connections, (btstack_linked_item_t*)gatt_client);
3328 
3329     // schedule emitted event if already connected, otherwise
3330     bool already_connected = false;
3331     hci_connection_t * hci_connection = hci_connection_for_bd_addr_and_type(addr, BD_ADDR_TYPE_ACL);
3332     if (hci_connection != NULL){
3333         if (hci_connection->att_server.l2cap_cid != 0){
3334             already_connected = true;
3335         }
3336     }
3337     gatt_client->callback_request.context = gatt_client;
3338     if (already_connected){
3339         gatt_client->con_handle = hci_connection->con_handle;
3340         gatt_client->callback_request.callback = &gatt_client_classic_emit_connected;
3341         gatt_client->state = P_W2_EMIT_CONNECTED;
3342         btstack_run_loop_execute_on_main_thread(&gatt_client->callback_request);
3343     } else {
3344         gatt_client->callback_request.callback = &gatt_client_classic_sdp_start;
3345         gatt_client->state = P_W2_SDP_QUERY;
3346         sdp_client_register_query_callback(&gatt_client->callback_request);
3347     }
3348     return ERROR_CODE_SUCCESS;
3349 }
3350 
3351 uint8_t gatt_client_classic_disconnect(btstack_packet_handler_t callback, hci_con_handle_t con_handle){
3352     gatt_client_t * gatt_client = gatt_client_get_context_for_handle(con_handle);
3353     if (gatt_client == NULL){
3354         return ERROR_CODE_UNKNOWN_CONNECTION_IDENTIFIER;
3355     }
3356     gatt_client->callback = callback;
3357     return l2cap_disconnect(gatt_client->l2cap_cid);
3358 }
3359 #endif
3360 
3361 #ifdef ENABLE_GATT_OVER_EATT
3362 
3363 #define MAX_NR_EATT_CHANNELS 5
3364 
3365 static void gatt_client_le_enhanced_packet_handler(uint8_t packet_type, uint16_t channel, uint8_t *packet, uint16_t size);
3366 
3367 static uint8_t gatt_client_le_enhanced_num_eatt_clients_in_state(gatt_client_t * gatt_client, gatt_client_state_t state){
3368     uint8_t num_clients = 0;
3369     btstack_linked_list_iterator_t it;
3370     btstack_linked_list_iterator_init(&it, &gatt_client->eatt_clients);
3371     while (btstack_linked_list_iterator_has_next(&it)){
3372         gatt_client_t * eatt_client = (gatt_client_t *) btstack_linked_list_iterator_next(&it);
3373         if (eatt_client->state == state){
3374             num_clients++;
3375         }
3376     }
3377     return num_clients;
3378 }
3379 
3380 static void gatt_client_eatt_finalize(gatt_client_t * gatt_client) {
3381     // free eatt clients
3382     btstack_linked_list_iterator_t it;
3383     btstack_linked_list_iterator_init(&it, &gatt_client_connections);
3384     while (btstack_linked_list_iterator_has_next(&it)) {
3385         gatt_client_t *eatt_client = (gatt_client_t *) btstack_linked_list_iterator_next(&it);
3386         btstack_linked_list_iterator_remove(&it);
3387         btstack_memory_gatt_client_free(eatt_client);
3388     }
3389 }
3390 
3391 // all channels connected
3392 static void gatt_client_le_enhanced_handle_connected(gatt_client_t * gatt_client, uint8_t status) {
3393     if (status == ERROR_CODE_SUCCESS){
3394         uint8_t num_ready = gatt_client_le_enhanced_num_eatt_clients_in_state(gatt_client, P_READY);
3395         if (num_ready > 0){
3396             gatt_client->eatt_state = GATT_CLIENT_EATT_READY;
3397             // free unused channels
3398             btstack_linked_list_iterator_t it;
3399             btstack_linked_list_iterator_init(&it, &gatt_client_connections);
3400             while (btstack_linked_list_iterator_has_next(&it)) {
3401                 gatt_client_t *eatt_client = (gatt_client_t *) btstack_linked_list_iterator_next(&it);
3402                 if (eatt_client->state == P_L2CAP_CLOSED){
3403                     btstack_linked_list_iterator_remove(&it);
3404                     btstack_memory_gatt_client_free(eatt_client);
3405                 }
3406             }
3407         } else {
3408             hci_connection_t * hci_connection = hci_connection_for_handle(gatt_client->con_handle);
3409             btstack_assert(hci_connection != NULL);
3410             if (hci_connection->att_server.incoming_connection_request){
3411                 hci_connection->att_server.incoming_connection_request = false;
3412                 log_info("Collision, retry in 100ms");
3413                 gatt_client->state = P_W2_L2CAP_CONNECT;
3414                 // set timer for retry
3415                 btstack_run_loop_set_timer(&gatt_client->gc_timeout, GATT_CLIENT_COLLISION_BACKOFF_MS);
3416                 btstack_run_loop_set_timer_handler(&gatt_client->gc_timeout, gatt_client_le_enhanced_retry);
3417                 btstack_run_loop_add_timer(&gatt_client->gc_timeout);
3418                 return;
3419             } else {
3420                 gatt_client->eatt_state = GATT_CLIENT_EATT_IDLE;
3421                 status = ERROR_CODE_CONNECTION_REJECTED_DUE_TO_LIMITED_RESOURCES;
3422             }
3423         }
3424     } else {
3425         gatt_client_eatt_finalize(gatt_client);
3426         gatt_client->eatt_state = GATT_CLIENT_EATT_IDLE;
3427     }
3428 
3429     gatt_client_emit_connected(gatt_client->callback, status, gatt_client->addr_type, gatt_client->addr, gatt_client->con_handle);
3430 }
3431 
3432 // single channel disconnected
3433 static void gatt_client_le_enhanced_handle_ecbm_disconnected(gatt_client_t * gatt_client, gatt_client_t * eatt_client) {
3434 
3435     // report error
3436     gatt_client_report_error_if_pending(eatt_client, ATT_ERROR_HCI_DISCONNECT_RECEIVED);
3437 
3438     // free memory
3439     btstack_linked_list_remove(&gatt_client->eatt_clients, (btstack_linked_item_t *) eatt_client);
3440     btstack_memory_gatt_client_free(eatt_client);
3441 
3442     // last channel
3443     if (btstack_linked_list_empty(&gatt_client->eatt_clients)){
3444         hci_connection_t * hci_connection = hci_connection_for_handle(gatt_client->con_handle);
3445         hci_connection->att_server.eatt_outgoing_active = false;
3446 
3447         if (gatt_client->eatt_state == GATT_CLIENT_EATT_READY) {
3448             // report disconnected if last channel closed
3449             uint8_t buffer[20];
3450             uint16_t len = hci_event_create_from_template_and_arguments(buffer, sizeof(buffer), &gatt_client_disconnected, gatt_client->con_handle);
3451             (*gatt_client->callback)(HCI_EVENT_PACKET, 0, buffer, len);
3452         }
3453     }
3454 }
3455 
3456 static gatt_client_t * gatt_client_le_enhanced_get_context_for_l2cap_cid(uint16_t l2cap_cid, gatt_client_t ** out_eatt_client){
3457     btstack_linked_list_iterator_t it;
3458     btstack_linked_list_iterator_init(&it, &gatt_client_connections);
3459     while (btstack_linked_list_iterator_has_next(&it)) {
3460         gatt_client_t * gatt_client = (gatt_client_t *) btstack_linked_list_iterator_next(&it);
3461         btstack_linked_list_iterator_t it2;
3462         btstack_linked_list_iterator_init(&it2, &gatt_client->eatt_clients);
3463         while (btstack_linked_list_iterator_has_next(&it2)) {
3464             gatt_client_t * eatt_client = (gatt_client_t *) btstack_linked_list_iterator_next(&it2);
3465             if (eatt_client->l2cap_cid == l2cap_cid){
3466                 *out_eatt_client = eatt_client;
3467                 return gatt_client;
3468             }
3469         }
3470     }
3471     return NULL;
3472 }
3473 
3474 static void gatt_client_le_enhanced_setup_l2cap_channel(gatt_client_t * gatt_client){
3475     uint8_t num_channels = gatt_client->eatt_num_clients;
3476 
3477     // setup channels
3478     uint16_t buffer_size_per_client = gatt_client->eatt_storage_size / num_channels;
3479     uint16_t max_mtu = (buffer_size_per_client - REPORT_PREBUFFER_HEADER) / 2;
3480     uint8_t * receive_buffers[MAX_NR_EATT_CHANNELS];
3481     uint16_t  new_cids[MAX_NR_EATT_CHANNELS];
3482     memset(gatt_client->eatt_storage_buffer, 0, gatt_client->eatt_storage_size);
3483     uint8_t i;
3484     for (i=0;i<gatt_client->eatt_num_clients; i++){
3485         receive_buffers[i] = &gatt_client->eatt_storage_buffer[REPORT_PREBUFFER_HEADER];
3486         gatt_client->eatt_storage_buffer += REPORT_PREBUFFER_HEADER + max_mtu;
3487     }
3488 
3489     log_info("%u EATT clients with receive buffer size %u", gatt_client->eatt_num_clients, buffer_size_per_client);
3490 
3491     uint8_t status = l2cap_ecbm_create_channels(&gatt_client_le_enhanced_packet_handler,
3492                                                 gatt_client->con_handle,
3493                                                 gatt_client->security_level,
3494                                                 BLUETOOTH_PSM_EATT, num_channels,
3495                                                 L2CAP_LE_AUTOMATIC_CREDITS,
3496                                                 buffer_size_per_client,
3497                                                 receive_buffers,
3498                                                 new_cids);
3499 
3500     if (status == ERROR_CODE_SUCCESS){
3501         i = 0;
3502         btstack_linked_list_iterator_t it;
3503         btstack_linked_list_iterator_init(&it, &gatt_client->eatt_clients);
3504         while (btstack_linked_list_iterator_has_next(&it)) {
3505             gatt_client_t *new_eatt_client = (gatt_client_t *) btstack_linked_list_iterator_next(&it);
3506 
3507             // init state with new cid and transmit buffer
3508             new_eatt_client->bearer_type = ATT_BEARER_ENHANCED_LE;
3509             new_eatt_client->con_handle = gatt_client->con_handle;
3510             new_eatt_client->mtu = 64;
3511             new_eatt_client->security_level = LEVEL_0;
3512             new_eatt_client->mtu_state = MTU_AUTO_EXCHANGE_DISABLED;
3513             new_eatt_client->state = P_W4_L2CAP_CONNECTION;
3514             new_eatt_client->l2cap_cid = new_cids[i];
3515             new_eatt_client->eatt_storage_buffer = gatt_client->eatt_storage_buffer;
3516             gatt_client->eatt_storage_buffer += max_mtu;
3517             i++;
3518         }
3519         gatt_client->eatt_state = GATT_CLIENT_EATT_L2CAP_SETUP;
3520     } else {
3521         gatt_client_le_enhanced_handle_connected(gatt_client, status);
3522     }
3523 }
3524 
3525 static void gatt_client_le_enhanced_retry(btstack_timer_source_t * ts){
3526     gatt_client_t * gatt_client = gatt_client_for_timer(ts);
3527     if (gatt_client != NULL){
3528         gatt_client->state = P_W4_L2CAP_CONNECTION;
3529         gatt_client_le_enhanced_setup_l2cap_channel(gatt_client);
3530     }
3531 }
3532 
3533 static void gatt_client_le_enhanced_packet_handler(uint8_t packet_type, uint16_t channel, uint8_t *packet, uint16_t size) {
3534     gatt_client_t *gatt_client;
3535     gatt_client_t *eatt_client;
3536     hci_con_handle_t con_handle;
3537     uint16_t l2cap_cid;
3538     uint8_t status;
3539     gatt_client_characteristic_t characteristic;
3540     gatt_client_service_t service;
3541     switch (packet_type) {
3542         case HCI_EVENT_PACKET:
3543             switch (hci_event_packet_get_type(packet)) {
3544                 case GATT_EVENT_SERVICE_QUERY_RESULT:
3545                     con_handle = gatt_event_service_query_result_get_handle(packet);
3546                     gatt_client = gatt_client_get_context_for_handle(con_handle);
3547                     btstack_assert(gatt_client != NULL);
3548                     btstack_assert(gatt_client->eatt_state == GATT_CLIENT_EATT_DISCOVER_GATT_SERVICE_W4_DONE);
3549                     gatt_event_service_query_result_get_service(packet, &service);
3550                     gatt_client->gatt_service_start_group_handle = service.start_group_handle;
3551                     gatt_client->gatt_service_end_group_handle = service.end_group_handle;
3552                     break;
3553                 case GATT_EVENT_CHARACTERISTIC_VALUE_QUERY_RESULT:
3554                     con_handle = gatt_event_characteristic_value_query_result_get_handle(packet);
3555                     gatt_client = gatt_client_get_context_for_handle(con_handle);
3556                     btstack_assert(gatt_client != NULL);
3557                     btstack_assert(gatt_client->eatt_state == GATT_CLIENT_EATT_READ_SERVER_SUPPORTED_FEATURES_W4_DONE);
3558                     if (gatt_event_characteristic_value_query_result_get_value_length(packet) >= 1) {
3559                         gatt_client->gatt_server_supported_features = gatt_event_characteristic_value_query_result_get_value(packet)[0];
3560                     }
3561                     break;
3562                 case GATT_EVENT_CHARACTERISTIC_QUERY_RESULT:
3563                     con_handle = gatt_event_characteristic_query_result_get_handle(packet);
3564                     gatt_client = gatt_client_get_context_for_handle(con_handle);
3565                     btstack_assert(gatt_client != NULL);
3566                     btstack_assert(gatt_client->eatt_state == GATT_CLIENT_EATT_FIND_CLIENT_SUPPORTED_FEATURES_W4_DONE);
3567                     gatt_event_characteristic_query_result_get_characteristic(packet, &characteristic);
3568                     gatt_client->gatt_client_supported_features_handle = characteristic.value_handle;
3569                     break;
3570                 case GATT_EVENT_QUERY_COMPLETE:
3571                     con_handle = gatt_event_query_complete_get_handle(packet);
3572                     gatt_client = gatt_client_get_context_for_handle(con_handle);
3573                     btstack_assert(gatt_client != NULL);
3574                     switch (gatt_client->eatt_state){
3575                         case GATT_CLIENT_EATT_DISCOVER_GATT_SERVICE_W4_DONE:
3576                             if (gatt_client->gatt_service_start_group_handle == 0){
3577                                 gatt_client_le_enhanced_handle_connected(gatt_client, ERROR_CODE_UNSUPPORTED_FEATURE_OR_PARAMETER_VALUE);
3578                             } else {
3579                                 gatt_client->eatt_state = GATT_CLIENT_EATT_READ_SERVER_SUPPORTED_FEATURES_W2_SEND;
3580                             }
3581                             break;
3582                         case GATT_CLIENT_EATT_READ_SERVER_SUPPORTED_FEATURES_W4_DONE:
3583                             if ((gatt_client->gatt_server_supported_features & 1) == 0) {
3584                                 gatt_client_le_enhanced_handle_connected(gatt_client, ERROR_CODE_UNSUPPORTED_FEATURE_OR_PARAMETER_VALUE);
3585                             } else {
3586                                 gatt_client->eatt_state = GATT_CLIENT_EATT_FIND_CLIENT_SUPPORTED_FEATURES_W2_SEND;
3587                             }
3588                             break;
3589                         case GATT_CLIENT_EATT_FIND_CLIENT_SUPPORTED_FEATURES_W4_DONE:
3590                             if (gatt_client->gatt_client_supported_features_handle == 0){
3591                                 gatt_client_le_enhanced_handle_connected(gatt_client, ERROR_CODE_UNSUPPORTED_FEATURE_OR_PARAMETER_VALUE);
3592                             } else {
3593                                 gatt_client->eatt_state = GATT_CLIENT_EATT_WRITE_ClIENT_SUPPORTED_FEATURES_W2_SEND;
3594                             }
3595                             break;
3596                         case GATT_CLIENT_EATT_WRITE_ClIENT_SUPPORTED_FEATURES_W4_DONE:
3597                             gatt_client_le_enhanced_setup_l2cap_channel(gatt_client);
3598                             break;
3599                         default:
3600                             break;
3601                     }
3602                     break;
3603                 case L2CAP_EVENT_ECBM_CHANNEL_OPENED:
3604                     l2cap_cid = l2cap_event_ecbm_channel_opened_get_local_cid(packet);
3605                     gatt_client = gatt_client_le_enhanced_get_context_for_l2cap_cid(l2cap_cid, &eatt_client);
3606 
3607                     btstack_assert(gatt_client != NULL);
3608                     btstack_assert(eatt_client != NULL);
3609                     btstack_assert(eatt_client->state == P_W4_L2CAP_CONNECTION);
3610 
3611                     status = l2cap_event_channel_opened_get_status(packet);
3612                     if (status == ERROR_CODE_SUCCESS){
3613                         eatt_client->state = P_READY;
3614                         eatt_client->mtu = l2cap_event_channel_opened_get_remote_mtu(packet);
3615                     } else {
3616                         eatt_client->state = P_L2CAP_CLOSED;
3617                     }
3618                     // connected if opened event for all channels received
3619                     if (gatt_client_le_enhanced_num_eatt_clients_in_state(gatt_client, P_W4_L2CAP_CONNECTION) == 0){
3620                         gatt_client_le_enhanced_handle_connected(gatt_client, ERROR_CODE_SUCCESS);
3621                     }
3622                     break;
3623                 case L2CAP_EVENT_CHANNEL_CLOSED:
3624                     l2cap_cid = l2cap_event_channel_closed_get_local_cid(packet);
3625                     gatt_client = gatt_client_le_enhanced_get_context_for_l2cap_cid(l2cap_cid, &eatt_client);
3626                     btstack_assert(gatt_client != NULL);
3627                     btstack_assert(eatt_client != NULL);
3628                     gatt_client_le_enhanced_handle_ecbm_disconnected(gatt_client, eatt_client);
3629                     break;
3630                 default:
3631                     break;
3632             }
3633             break;
3634         case L2CAP_DATA_PACKET:
3635             gatt_client = gatt_client_le_enhanced_get_context_for_l2cap_cid(channel, &eatt_client);
3636             btstack_assert(gatt_client != NULL);
3637             btstack_assert(eatt_client != NULL);
3638             gatt_client_handle_att_response(eatt_client, packet, size);
3639             gatt_client_run();
3640             break;
3641         default:
3642             break;
3643     }
3644 }
3645 
3646 static bool gatt_client_le_enhanced_handle_can_send_query(gatt_client_t * gatt_client){
3647     uint8_t status = ERROR_CODE_SUCCESS;
3648     uint8_t gatt_client_supported_features = 0x06; // eatt + multiple value notifications
3649     switch (gatt_client->eatt_state){
3650         case GATT_CLIENT_EATT_DISCOVER_GATT_SERVICE_W2_SEND:
3651             gatt_client->gatt_service_start_group_handle = 0;
3652             gatt_client->eatt_state = GATT_CLIENT_EATT_DISCOVER_GATT_SERVICE_W4_DONE;
3653             status = gatt_client_discover_primary_services_by_uuid16(&gatt_client_le_enhanced_packet_handler,
3654                                                                      gatt_client->con_handle,
3655                                                                      ORG_BLUETOOTH_SERVICE_GENERIC_ATTRIBUTE);
3656             break;
3657         case GATT_CLIENT_EATT_READ_SERVER_SUPPORTED_FEATURES_W2_SEND:
3658             gatt_client->gatt_server_supported_features = 0;
3659             gatt_client->eatt_state = GATT_CLIENT_EATT_READ_SERVER_SUPPORTED_FEATURES_W4_DONE;
3660             status = gatt_client_read_value_of_characteristics_by_uuid16(&gatt_client_le_enhanced_packet_handler,
3661                                                                          gatt_client->con_handle,
3662                                                                          gatt_client->gatt_service_start_group_handle,
3663                                                                          gatt_client->gatt_service_end_group_handle,
3664                                                                          ORG_BLUETOOTH_CHARACTERISTIC_SERVER_SUPPORTED_FEATURES);
3665             return true;
3666         case GATT_CLIENT_EATT_FIND_CLIENT_SUPPORTED_FEATURES_W2_SEND:
3667             gatt_client->gatt_client_supported_features_handle = 0;
3668             gatt_client->eatt_state = GATT_CLIENT_EATT_FIND_CLIENT_SUPPORTED_FEATURES_W4_DONE;
3669             status = gatt_client_discover_characteristics_for_handle_range_by_uuid16(&gatt_client_le_enhanced_packet_handler,
3670                                                                                      gatt_client->con_handle,
3671                                                                                      gatt_client->gatt_service_start_group_handle,
3672                                                                                      gatt_client->gatt_service_end_group_handle,
3673                                                                                      ORG_BLUETOOTH_CHARACTERISTIC_CLIENT_SUPPORTED_FEATURES);
3674             return true;
3675         case GATT_CLIENT_EATT_WRITE_ClIENT_SUPPORTED_FEATURES_W2_SEND:
3676             gatt_client->eatt_state = GATT_CLIENT_EATT_WRITE_ClIENT_SUPPORTED_FEATURES_W4_DONE;
3677             status = gatt_client_write_value_of_characteristic(&gatt_client_le_enhanced_packet_handler, gatt_client->con_handle,
3678                                                                gatt_client->gatt_client_supported_features_handle, 1,
3679                                                                &gatt_client_supported_features);
3680             return true;
3681         default:
3682             break;
3683     }
3684     btstack_assert(status == ERROR_CODE_SUCCESS);
3685     UNUSED(status);
3686     return false;
3687 }
3688 
3689 uint8_t gatt_client_le_enhanced_connect(btstack_packet_handler_t callback, hci_con_handle_t con_handle, uint8_t num_channels, uint8_t * storage_buffer, uint16_t storage_size) {
3690     gatt_client_t * gatt_client;
3691     uint8_t status = gatt_client_provide_context_for_handle(con_handle, &gatt_client);
3692     if (status != ERROR_CODE_SUCCESS){
3693         return status;
3694     }
3695 
3696     if (gatt_client->eatt_state != GATT_CLIENT_EATT_IDLE){
3697         return ERROR_CODE_COMMAND_DISALLOWED;
3698     }
3699 
3700     // need one buffer for sending and one for receiving. Receiving includes pre-buffer for reports
3701     uint16_t buffer_size_per_client = storage_size / num_channels;
3702     uint16_t max_mtu = (buffer_size_per_client - REPORT_PREBUFFER_HEADER) / 2;
3703     if (max_mtu < 64) {
3704         return ERROR_CODE_INVALID_HCI_COMMAND_PARAMETERS;
3705     }
3706 
3707     if ((num_channels == 0) || (num_channels > MAX_NR_EATT_CHANNELS)){
3708         return ERROR_CODE_INVALID_HCI_COMMAND_PARAMETERS;
3709     }
3710 
3711     // create max num_channel eatt clients
3712     uint8_t i;
3713     btstack_linked_list_t eatt_clients = NULL;
3714     for (i=0;i<num_channels;i++) {
3715         gatt_client_t * new_gatt_client = btstack_memory_gatt_client_get();
3716         if (new_gatt_client == NULL) {
3717             break;
3718         }
3719         btstack_linked_list_add(&eatt_clients, (btstack_linked_item_t*)new_gatt_client);
3720     }
3721 
3722     if (i != num_channels){
3723         while (true){
3724             gatt_client = (gatt_client_t *) btstack_linked_list_pop(&eatt_clients);
3725             if (gatt_client == NULL) {
3726                 break;
3727             }
3728             btstack_memory_gatt_client_free(gatt_client);
3729         }
3730         return ERROR_CODE_MEMORY_CAPACITY_EXCEEDED;
3731     }
3732 
3733     hci_connection_t * hci_connection = hci_connection_for_handle(con_handle);
3734     hci_connection->att_server.eatt_outgoing_active = true;
3735 
3736     gatt_client->callback = callback;
3737     gatt_client->eatt_num_clients   = num_channels;
3738     gatt_client->eatt_storage_buffer = storage_buffer;
3739     gatt_client->eatt_storage_size   = storage_size;
3740     gatt_client->eatt_clients = eatt_clients;
3741     gatt_client->eatt_state = GATT_CLIENT_EATT_DISCOVER_GATT_SERVICE_W2_SEND;
3742     gatt_client_notify_can_send_query(gatt_client);
3743 
3744     return ERROR_CODE_SUCCESS;
3745 }
3746 
3747 #endif
3748 
3749 #ifdef FUZZING_BUILD_MODE_UNSAFE_FOR_PRODUCTION
3750 void gatt_client_att_packet_handler_fuzz(uint8_t packet_type, uint16_t handle, uint8_t *packet, uint16_t size){
3751     gatt_client_att_packet_handler(packet_type, handle, packet, size);
3752 }
3753 
3754 uint8_t gatt_client_get_client(hci_con_handle_t con_handle, gatt_client_t ** out_gatt_client){
3755     uint8_t status = gatt_client_provide_context_for_handle(con_handle, out_gatt_client);
3756     return status;
3757 }
3758 #endif
3759