xref: /btstack/src/ble/gatt_client.c (revision ec9babacc577799c985a0ae8277a2a2d625e9e54)
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 MATTHIAS
24  * RINGWALD 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 
43 #include "btstack_config.h"
44 
45 #include "att_dispatch.h"
46 #include "ad_parser.h"
47 #include "ble/att_db.h"
48 #include "ble/core.h"
49 #include "ble/gatt_client.h"
50 #include "ble/le_device_db.h"
51 #include "ble/sm.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 "classic/sdp_util.h"
58 #include "hci.h"
59 #include "hci_cmd.h"
60 #include "hci_dump.h"
61 #include "l2cap.h"
62 
63 static btstack_linked_list_t gatt_client_connections;
64 static btstack_linked_list_t gatt_client_value_listeners;
65 static btstack_packet_callback_registration_t hci_event_callback_registration;
66 
67 #if defined(ENABLE_GATT_CLIENT_PAIRING) || defined (ENABLE_LE_SIGNED_WRITE) || defined (ENABLE_LE_PROACTIVE_AUTHENTICATION)
68 static btstack_packet_callback_registration_t sm_event_callback_registration;
69 #endif
70 
71 static uint8_t mtu_exchange_enabled;
72 
73 static void gatt_client_att_packet_handler(uint8_t packet_type, uint16_t handle, uint8_t *packet, uint16_t size);
74 static void gatt_client_event_packet_handler(uint8_t packet_type, uint16_t channel, uint8_t *packet, uint16_t size);
75 static void gatt_client_report_error_if_pending(gatt_client_t *gatt_client, uint8_t att_error_code);
76 
77 #ifdef ENABLE_LE_SIGNED_WRITE
78 static void att_signed_write_handle_cmac_result(uint8_t hash[8]);
79 #endif
80 
81 void gatt_client_init(void){
82     gatt_client_connections = NULL;
83     mtu_exchange_enabled = 1;
84 
85     // regsister for HCI Events
86     hci_event_callback_registration.callback = &gatt_client_event_packet_handler;
87     hci_add_event_handler(&hci_event_callback_registration);
88 
89 #if defined(ENABLE_GATT_CLIENT_PAIRING) || defined (ENABLE_LE_SIGNED_WRITE) || defined (ENABLE_LE_PROACTIVE_AUTHENTICATION)
90     // register for SM Events
91     sm_event_callback_registration.callback = &gatt_client_event_packet_handler;
92     sm_add_event_handler(&sm_event_callback_registration);
93 #endif
94 
95     // and ATT Client PDUs
96     att_dispatch_register_client(gatt_client_att_packet_handler);
97 }
98 
99 static gatt_client_t * gatt_client_for_timer(btstack_timer_source_t * ts){
100     btstack_linked_list_iterator_t it;
101     btstack_linked_list_iterator_init(&it, &gatt_client_connections);
102     while (btstack_linked_list_iterator_has_next(&it)){
103         gatt_client_t * gatt_client = (gatt_client_t *) btstack_linked_list_iterator_next(&it);
104         if (&gatt_client->gc_timeout == ts) {
105             return gatt_client;
106         }
107     }
108     return NULL;
109 }
110 
111 static void gatt_client_timeout_handler(btstack_timer_source_t * timer){
112     gatt_client_t * gatt_client = gatt_client_for_timer(timer);
113     if (gatt_client == NULL) return;
114     log_info("GATT client timeout handle, handle 0x%02x", gatt_client->con_handle);
115     gatt_client_report_error_if_pending(gatt_client, ATT_ERROR_TIMEOUT);
116 }
117 
118 static void gatt_client_timeout_start(gatt_client_t * gatt_client){
119     log_info("GATT client timeout start, handle 0x%02x", gatt_client->con_handle);
120     btstack_run_loop_remove_timer(&gatt_client->gc_timeout);
121     btstack_run_loop_set_timer_handler(&gatt_client->gc_timeout, gatt_client_timeout_handler);
122     btstack_run_loop_set_timer(&gatt_client->gc_timeout, 30000); // 30 seconds sm timeout
123     btstack_run_loop_add_timer(&gatt_client->gc_timeout);
124 }
125 
126 static void gatt_client_timeout_stop(gatt_client_t * gatt_client){
127     log_info("GATT client timeout stop, handle 0x%02x", gatt_client->con_handle);
128     btstack_run_loop_remove_timer(&gatt_client->gc_timeout);
129 }
130 
131 static gatt_client_t * gatt_client_get_context_for_handle(uint16_t handle){
132     btstack_linked_item_t *it;
133     for (it = (btstack_linked_item_t *) gatt_client_connections; it != NULL; it = it->next){
134         gatt_client_t * gatt_client = (gatt_client_t *) it;
135         if (gatt_client->con_handle == handle){
136             return gatt_client;
137         }
138     }
139     return NULL;
140 }
141 
142 
143 // @returns gatt_client context
144 // returns existing one, or tries to setup new one
145 static gatt_client_t * gatt_client_provide_context_for_handle(hci_con_handle_t con_handle){
146     gatt_client_t * gatt_client = gatt_client_get_context_for_handle(con_handle);
147     if (gatt_client) return gatt_client;
148 
149     // bail if no such hci connection
150     if (!hci_connection_for_handle(con_handle)){
151         log_error("No connection for handle 0x%04x", con_handle);
152         return NULL;
153     }
154     gatt_client = btstack_memory_gatt_client_get();
155     if (!gatt_client) return NULL;
156     // init state
157     gatt_client->con_handle = con_handle;
158     gatt_client->mtu = ATT_DEFAULT_MTU;
159     if (mtu_exchange_enabled){
160         gatt_client->mtu_state = SEND_MTU_EXCHANGE;
161     } else {
162         gatt_client->mtu_state = MTU_AUTO_EXCHANGE_DISABLED;
163     }
164     gatt_client->gatt_client_state = P_READY;
165     btstack_linked_list_add(&gatt_client_connections, (btstack_linked_item_t*)gatt_client);
166     return gatt_client;
167 }
168 
169 static gatt_client_t * gatt_client_provide_context_for_handle_and_start_timer(hci_con_handle_t con_handle){
170     gatt_client_t * gatt_client = gatt_client_provide_context_for_handle(con_handle);
171     if (gatt_client == NULL) return NULL;
172     gatt_client_timeout_start(gatt_client);
173     return gatt_client;
174 }
175 
176 static int is_ready(gatt_client_t * gatt_client){
177     return gatt_client->gatt_client_state == P_READY;
178 }
179 
180 int gatt_client_is_ready(hci_con_handle_t con_handle){
181     gatt_client_t * gatt_client = gatt_client_provide_context_for_handle(con_handle);
182     if (gatt_client == NULL) return 0;
183     return is_ready(gatt_client);
184 }
185 
186 void gatt_client_mtu_enable_auto_negotiation(uint8_t enabled){
187     mtu_exchange_enabled = enabled;
188 }
189 
190 uint8_t gatt_client_get_mtu(hci_con_handle_t con_handle, uint16_t * mtu){
191     gatt_client_t * gatt_client = gatt_client_provide_context_for_handle(con_handle);
192     if (gatt_client == NULL) return BTSTACK_MEMORY_ALLOC_FAILED;
193 
194     if ((gatt_client->mtu_state == MTU_EXCHANGED) || (gatt_client->mtu_state == MTU_AUTO_EXCHANGE_DISABLED)){
195         *mtu = gatt_client->mtu;
196         return ERROR_CODE_SUCCESS;
197     }
198     *mtu = ATT_DEFAULT_MTU;
199     return GATT_CLIENT_IN_WRONG_STATE;
200 }
201 
202 // precondition: can_send_packet_now == TRUE
203 static uint8_t att_confirmation(uint16_t con_handle){
204     l2cap_reserve_packet_buffer();
205     uint8_t * request = l2cap_get_outgoing_buffer();
206     request[0] = ATT_HANDLE_VALUE_CONFIRMATION;
207 
208     return l2cap_send_prepared_connectionless(con_handle, L2CAP_CID_ATTRIBUTE_PROTOCOL, 1);
209 }
210 
211 // precondition: can_send_packet_now == TRUE
212 static uint8_t att_find_information_request(uint16_t request_type, uint16_t con_handle, uint16_t start_handle, uint16_t end_handle){
213     l2cap_reserve_packet_buffer();
214     uint8_t * request = l2cap_get_outgoing_buffer();
215     request[0] = request_type;
216     little_endian_store_16(request, 1, start_handle);
217     little_endian_store_16(request, 3, end_handle);
218 
219     return l2cap_send_prepared_connectionless(con_handle, L2CAP_CID_ATTRIBUTE_PROTOCOL, 5);
220 }
221 
222 // precondition: can_send_packet_now == TRUE
223 static uint8_t att_find_by_type_value_request(uint16_t request_type, uint16_t attribute_group_type, uint16_t con_handle, uint16_t start_handle, uint16_t end_handle, uint8_t * value, uint16_t value_size){
224     l2cap_reserve_packet_buffer();
225     uint8_t * request = l2cap_get_outgoing_buffer();
226 
227     request[0] = request_type;
228     little_endian_store_16(request, 1, start_handle);
229     little_endian_store_16(request, 3, end_handle);
230     little_endian_store_16(request, 5, attribute_group_type);
231     (void)memcpy(&request[7], value, value_size);
232 
233     return l2cap_send_prepared_connectionless(con_handle, L2CAP_CID_ATTRIBUTE_PROTOCOL, 7u + value_size);
234 }
235 
236 // precondition: can_send_packet_now == TRUE
237 static uint8_t att_read_by_type_or_group_request_for_uuid16(uint16_t request_type, uint16_t uuid16, uint16_t con_handle, uint16_t start_handle, uint16_t end_handle){
238     l2cap_reserve_packet_buffer();
239     uint8_t * request = l2cap_get_outgoing_buffer();
240     request[0] = request_type;
241     little_endian_store_16(request, 1, start_handle);
242     little_endian_store_16(request, 3, end_handle);
243     little_endian_store_16(request, 5, uuid16);
244 
245     return l2cap_send_prepared_connectionless(con_handle, L2CAP_CID_ATTRIBUTE_PROTOCOL, 7);
246 }
247 
248 // precondition: can_send_packet_now == TRUE
249 static uint8_t att_read_by_type_or_group_request_for_uuid128(uint16_t request_type, uint8_t * uuid128, uint16_t con_handle, uint16_t start_handle, uint16_t end_handle){
250     l2cap_reserve_packet_buffer();
251     uint8_t * request = l2cap_get_outgoing_buffer();
252     request[0] = request_type;
253     little_endian_store_16(request, 1, start_handle);
254     little_endian_store_16(request, 3, end_handle);
255     reverse_128(uuid128, &request[5]);
256 
257     return l2cap_send_prepared_connectionless(con_handle, L2CAP_CID_ATTRIBUTE_PROTOCOL, 21);
258 }
259 
260 // precondition: can_send_packet_now == TRUE
261 static uint8_t att_read_request(uint16_t request_type, uint16_t con_handle, uint16_t attribute_handle){
262     l2cap_reserve_packet_buffer();
263     uint8_t * request = l2cap_get_outgoing_buffer();
264     request[0] = request_type;
265     little_endian_store_16(request, 1, attribute_handle);
266 
267     return l2cap_send_prepared_connectionless(con_handle, L2CAP_CID_ATTRIBUTE_PROTOCOL, 3);
268 }
269 
270 // precondition: can_send_packet_now == TRUE
271 static uint8_t att_read_blob_request(uint16_t request_type, uint16_t con_handle, uint16_t attribute_handle, uint16_t value_offset){
272     l2cap_reserve_packet_buffer();
273     uint8_t * request = l2cap_get_outgoing_buffer();
274     request[0] = request_type;
275     little_endian_store_16(request, 1, attribute_handle);
276     little_endian_store_16(request, 3, value_offset);
277 
278     return l2cap_send_prepared_connectionless(con_handle, L2CAP_CID_ATTRIBUTE_PROTOCOL, 5);
279 }
280 
281 static uint8_t att_read_multiple_request(uint16_t con_handle, uint16_t num_value_handles, uint16_t * value_handles){
282     l2cap_reserve_packet_buffer();
283     uint8_t * request = l2cap_get_outgoing_buffer();
284     request[0] = ATT_READ_MULTIPLE_REQUEST;
285     int i;
286     int offset = 1;
287     for (i=0;i<num_value_handles;i++){
288         little_endian_store_16(request, offset, value_handles[i]);
289         offset += 2;
290     }
291 
292     return l2cap_send_prepared_connectionless(con_handle, L2CAP_CID_ATTRIBUTE_PROTOCOL, offset);
293 }
294 
295 #ifdef ENABLE_LE_SIGNED_WRITE
296 // precondition: can_send_packet_now == TRUE
297 static uint8_t att_signed_write_request(uint16_t request_type, uint16_t con_handle, uint16_t attribute_handle, uint16_t value_length, uint8_t * value, uint32_t sign_counter, uint8_t sgn[8]){
298     l2cap_reserve_packet_buffer();
299     uint8_t * request = l2cap_get_outgoing_buffer();
300     request[0] = request_type;
301     little_endian_store_16(request, 1, attribute_handle);
302     (void)memcpy(&request[3], value, value_length);
303     little_endian_store_32(request, 3 + value_length, sign_counter);
304     reverse_64(sgn, &request[3 + value_length + 4]);
305 
306     return l2cap_send_prepared_connectionless(con_handle, L2CAP_CID_ATTRIBUTE_PROTOCOL, 3 + value_length + 12);
307 }
308 #endif
309 
310 // precondition: can_send_packet_now == TRUE
311 static uint8_t att_write_request(uint16_t request_type, uint16_t con_handle, uint16_t attribute_handle, uint16_t value_length, uint8_t * value){
312     l2cap_reserve_packet_buffer();
313     uint8_t * request = l2cap_get_outgoing_buffer();
314     request[0] = request_type;
315     little_endian_store_16(request, 1, attribute_handle);
316     (void)memcpy(&request[3], value, value_length);
317 
318     return l2cap_send_prepared_connectionless(con_handle, L2CAP_CID_ATTRIBUTE_PROTOCOL, 3u + value_length);
319 }
320 
321 // precondition: can_send_packet_now == TRUE
322 static uint8_t att_execute_write_request(uint16_t request_type, uint16_t con_handle, uint8_t execute_write){
323     l2cap_reserve_packet_buffer();
324     uint8_t * request = l2cap_get_outgoing_buffer();
325     request[0] = request_type;
326     request[1] = execute_write;
327 
328     return l2cap_send_prepared_connectionless(con_handle, L2CAP_CID_ATTRIBUTE_PROTOCOL, 2);
329 }
330 
331 // precondition: can_send_packet_now == TRUE
332 static uint8_t att_prepare_write_request(uint16_t request_type, uint16_t con_handle, uint16_t attribute_handle, uint16_t value_offset, uint16_t blob_length, uint8_t * value){
333     l2cap_reserve_packet_buffer();
334     uint8_t * request = l2cap_get_outgoing_buffer();
335     request[0] = request_type;
336     little_endian_store_16(request, 1, attribute_handle);
337     little_endian_store_16(request, 3, value_offset);
338     (void)memcpy(&request[5], &value[value_offset], blob_length);
339 
340     return l2cap_send_prepared_connectionless(con_handle, L2CAP_CID_ATTRIBUTE_PROTOCOL, 5u + blob_length);
341 }
342 
343 static uint8_t att_exchange_mtu_request(uint16_t con_handle){
344     uint16_t mtu = l2cap_max_le_mtu();
345     l2cap_reserve_packet_buffer();
346     uint8_t * request = l2cap_get_outgoing_buffer();
347     request[0] = ATT_EXCHANGE_MTU_REQUEST;
348     little_endian_store_16(request, 1, mtu);
349 
350     return l2cap_send_prepared_connectionless(con_handle, L2CAP_CID_ATTRIBUTE_PROTOCOL, 3);
351 }
352 
353 static uint16_t write_blob_length(gatt_client_t * gatt_client){
354     uint16_t max_blob_length = gatt_client->mtu - 5u;
355     if (gatt_client->attribute_offset >= gatt_client->attribute_length) {
356         return 0;
357     }
358     uint16_t rest_length = gatt_client->attribute_length - gatt_client->attribute_offset;
359     if (max_blob_length > rest_length){
360         return rest_length;
361     }
362     return max_blob_length;
363 }
364 
365 static void send_gatt_services_request(gatt_client_t *gatt_client){
366     att_read_by_type_or_group_request_for_uuid16(ATT_READ_BY_GROUP_TYPE_REQUEST, GATT_PRIMARY_SERVICE_UUID, gatt_client->con_handle, gatt_client->start_group_handle, gatt_client->end_group_handle);
367 }
368 
369 static void send_gatt_by_uuid_request(gatt_client_t *gatt_client, uint16_t attribute_group_type){
370     if (gatt_client->uuid16){
371         uint8_t uuid16[2];
372         little_endian_store_16(uuid16, 0, gatt_client->uuid16);
373         att_find_by_type_value_request(ATT_FIND_BY_TYPE_VALUE_REQUEST, attribute_group_type, gatt_client->con_handle, gatt_client->start_group_handle, gatt_client->end_group_handle, uuid16, 2);
374         return;
375     }
376     uint8_t uuid128[16];
377     reverse_128(gatt_client->uuid128, uuid128);
378     att_find_by_type_value_request(ATT_FIND_BY_TYPE_VALUE_REQUEST, attribute_group_type, gatt_client->con_handle, gatt_client->start_group_handle, gatt_client->end_group_handle, uuid128, 16);
379 }
380 
381 static void send_gatt_services_by_uuid_request(gatt_client_t *gatt_client){
382     send_gatt_by_uuid_request(gatt_client, GATT_PRIMARY_SERVICE_UUID);
383 }
384 
385 static void send_gatt_included_service_uuid_request(gatt_client_t *gatt_client){
386     att_read_request(ATT_READ_REQUEST, gatt_client->con_handle, gatt_client->query_start_handle);
387 }
388 
389 static void send_gatt_included_service_request(gatt_client_t *gatt_client){
390     att_read_by_type_or_group_request_for_uuid16(ATT_READ_BY_TYPE_REQUEST, GATT_INCLUDE_SERVICE_UUID, gatt_client->con_handle, gatt_client->start_group_handle, gatt_client->end_group_handle);
391 }
392 
393 static void send_gatt_characteristic_request(gatt_client_t *gatt_client){
394     att_read_by_type_or_group_request_for_uuid16(ATT_READ_BY_TYPE_REQUEST, GATT_CHARACTERISTICS_UUID, gatt_client->con_handle, gatt_client->start_group_handle, gatt_client->end_group_handle);
395 }
396 
397 static void send_gatt_characteristic_descriptor_request(gatt_client_t *gatt_client){
398     att_find_information_request(ATT_FIND_INFORMATION_REQUEST, gatt_client->con_handle, gatt_client->start_group_handle, gatt_client->end_group_handle);
399 }
400 
401 static void send_gatt_read_characteristic_value_request(gatt_client_t *gatt_client){
402     att_read_request(ATT_READ_REQUEST, gatt_client->con_handle, gatt_client->attribute_handle);
403 }
404 
405 static void send_gatt_read_by_type_request(gatt_client_t * gatt_client){
406     if (gatt_client->uuid16){
407         att_read_by_type_or_group_request_for_uuid16(ATT_READ_BY_TYPE_REQUEST, gatt_client->uuid16, gatt_client->con_handle, gatt_client->start_group_handle, gatt_client->end_group_handle);
408     } else {
409         att_read_by_type_or_group_request_for_uuid128(ATT_READ_BY_TYPE_REQUEST, gatt_client->uuid128, gatt_client->con_handle, gatt_client->start_group_handle, gatt_client->end_group_handle);
410     }
411 }
412 
413 static void send_gatt_read_blob_request(gatt_client_t *gatt_client){
414     att_read_blob_request(ATT_READ_BLOB_REQUEST, gatt_client->con_handle, gatt_client->attribute_handle, gatt_client->attribute_offset);
415 }
416 
417 static void send_gatt_read_multiple_request(gatt_client_t * gatt_client){
418     att_read_multiple_request(gatt_client->con_handle, gatt_client->read_multiple_handle_count, gatt_client->read_multiple_handles);
419 }
420 
421 static void send_gatt_write_attribute_value_request(gatt_client_t * gatt_client){
422     att_write_request(ATT_WRITE_REQUEST, gatt_client->con_handle, gatt_client->attribute_handle, gatt_client->attribute_length, gatt_client->attribute_value);
423 }
424 
425 static void send_gatt_write_client_characteristic_configuration_request(gatt_client_t * gatt_client){
426     att_write_request(ATT_WRITE_REQUEST, gatt_client->con_handle, gatt_client->client_characteristic_configuration_handle, 2, gatt_client->client_characteristic_configuration_value);
427 }
428 
429 static void send_gatt_prepare_write_request(gatt_client_t * gatt_client){
430     att_prepare_write_request(ATT_PREPARE_WRITE_REQUEST, gatt_client->con_handle, gatt_client->attribute_handle, gatt_client->attribute_offset, write_blob_length(gatt_client), gatt_client->attribute_value);
431 }
432 
433 static void send_gatt_execute_write_request(gatt_client_t * gatt_client){
434     att_execute_write_request(ATT_EXECUTE_WRITE_REQUEST, gatt_client->con_handle, 1);
435 }
436 
437 static void send_gatt_cancel_prepared_write_request(gatt_client_t * gatt_client){
438     att_execute_write_request(ATT_EXECUTE_WRITE_REQUEST, gatt_client->con_handle, 0);
439 }
440 
441 #ifndef ENABLE_GATT_FIND_INFORMATION_FOR_CCC_DISCOVERY
442 static void send_gatt_read_client_characteristic_configuration_request(gatt_client_t * gatt_client){
443     att_read_by_type_or_group_request_for_uuid16(ATT_READ_BY_TYPE_REQUEST, GATT_CLIENT_CHARACTERISTICS_CONFIGURATION, gatt_client->con_handle, gatt_client->start_group_handle, gatt_client->end_group_handle);
444 }
445 #endif
446 
447 static void send_gatt_read_characteristic_descriptor_request(gatt_client_t * gatt_client){
448     att_read_request(ATT_READ_REQUEST, gatt_client->con_handle, gatt_client->attribute_handle);
449 }
450 
451 #ifdef ENABLE_LE_SIGNED_WRITE
452 static void send_gatt_signed_write_request(gatt_client_t * gatt_client, uint32_t sign_counter){
453     att_signed_write_request(ATT_SIGNED_WRITE_COMMAND, gatt_client->con_handle, gatt_client->attribute_handle, gatt_client->attribute_length, gatt_client->attribute_value, sign_counter, gatt_client->cmac);
454 }
455 #endif
456 
457 static uint16_t get_last_result_handle_from_service_list(uint8_t * packet, uint16_t size){
458     uint8_t attr_length = packet[1];
459     return little_endian_read_16(packet, size - attr_length + 2u);
460 }
461 
462 static uint16_t get_last_result_handle_from_characteristics_list(uint8_t * packet, uint16_t size){
463     uint8_t attr_length = packet[1];
464     return little_endian_read_16(packet, size - attr_length + 3u);
465 }
466 
467 static uint16_t get_last_result_handle_from_included_services_list(uint8_t * packet, uint16_t size){
468     uint8_t attr_length = packet[1];
469     return little_endian_read_16(packet, size - attr_length);
470 }
471 
472 static void gatt_client_handle_transaction_complete(gatt_client_t * gatt_client){
473     gatt_client->gatt_client_state = P_READY;
474     gatt_client_timeout_stop(gatt_client);
475 }
476 
477 static void emit_event_new(btstack_packet_handler_t callback, uint8_t * packet, uint16_t size){
478     if (!callback) return;
479     hci_dump_packet(HCI_EVENT_PACKET, 0, packet, size);
480     (*callback)(HCI_EVENT_PACKET, 0, packet, size);
481 }
482 
483 void gatt_client_listen_for_characteristic_value_updates(gatt_client_notification_t * notification, btstack_packet_handler_t packet_handler, hci_con_handle_t con_handle, gatt_client_characteristic_t * characteristic){
484     notification->callback = packet_handler;
485     notification->con_handle = con_handle;
486     if (characteristic == NULL){
487         notification->attribute_handle = GATT_CLIENT_ANY_VALUE_HANDLE;
488     } else {
489         notification->attribute_handle = characteristic->value_handle;
490     }
491     btstack_linked_list_add(&gatt_client_value_listeners, (btstack_linked_item_t*) notification);
492 }
493 
494 void gatt_client_stop_listening_for_characteristic_value_updates(gatt_client_notification_t * notification){
495     btstack_linked_list_remove(&gatt_client_value_listeners, (btstack_linked_item_t*) notification);
496 }
497 
498 static void emit_event_to_registered_listeners(hci_con_handle_t con_handle, uint16_t attribute_handle, uint8_t * packet, uint16_t size){
499     btstack_linked_list_iterator_t it;
500     btstack_linked_list_iterator_init(&it, &gatt_client_value_listeners);
501     while (btstack_linked_list_iterator_has_next(&it)){
502         gatt_client_notification_t * notification = (gatt_client_notification_t*) btstack_linked_list_iterator_next(&it);
503         if ((notification->con_handle       != GATT_CLIENT_ANY_CONNECTION)   && (notification->con_handle       != con_handle)) continue;
504         if ((notification->attribute_handle != GATT_CLIENT_ANY_VALUE_HANDLE) && (notification->attribute_handle != attribute_handle)) continue;
505         (*notification->callback)(HCI_EVENT_PACKET, 0, packet, size);
506     }
507 }
508 
509 static void emit_gatt_complete_event(gatt_client_t * gatt_client, uint8_t att_status){
510     // @format H1
511     uint8_t packet[5];
512     packet[0] = GATT_EVENT_QUERY_COMPLETE;
513     packet[1] = 3;
514     little_endian_store_16(packet, 2, gatt_client->con_handle);
515     packet[4] = att_status;
516     emit_event_new(gatt_client->callback, packet, sizeof(packet));
517 }
518 
519 static void emit_gatt_service_query_result_event(gatt_client_t * gatt_client, uint16_t start_group_handle, uint16_t end_group_handle, uint8_t * uuid128){
520     // @format HX
521     uint8_t packet[24];
522     packet[0] = GATT_EVENT_SERVICE_QUERY_RESULT;
523     packet[1] = sizeof(packet) - 2u;
524     little_endian_store_16(packet, 2, gatt_client->con_handle);
525     ///
526     little_endian_store_16(packet, 4, start_group_handle);
527     little_endian_store_16(packet, 6, end_group_handle);
528     reverse_128(uuid128, &packet[8]);
529     emit_event_new(gatt_client->callback, packet, sizeof(packet));
530 }
531 
532 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, uint8_t * uuid128){
533     // @format HX
534     uint8_t packet[26];
535     packet[0] = GATT_EVENT_INCLUDED_SERVICE_QUERY_RESULT;
536     packet[1] = sizeof(packet) - 2u;
537     little_endian_store_16(packet, 2, gatt_client->con_handle);
538     ///
539     little_endian_store_16(packet, 4, include_handle);
540     //
541     little_endian_store_16(packet, 6, start_group_handle);
542     little_endian_store_16(packet, 8, end_group_handle);
543     reverse_128(uuid128, &packet[10]);
544     emit_event_new(gatt_client->callback, packet, sizeof(packet));
545 }
546 
547 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,
548                                                         uint16_t properties, uint8_t * uuid128){
549     // @format HY
550     uint8_t packet[28];
551     packet[0] = GATT_EVENT_CHARACTERISTIC_QUERY_RESULT;
552     packet[1] = sizeof(packet) - 2u;
553     little_endian_store_16(packet, 2, gatt_client->con_handle);
554     ///
555     little_endian_store_16(packet, 4,  start_handle);
556     little_endian_store_16(packet, 6,  value_handle);
557     little_endian_store_16(packet, 8,  end_handle);
558     little_endian_store_16(packet, 10, properties);
559     reverse_128(uuid128, &packet[12]);
560     emit_event_new(gatt_client->callback, packet, sizeof(packet));
561 }
562 
563 static void emit_gatt_all_characteristic_descriptors_result_event(
564         gatt_client_t * gatt_client, uint16_t descriptor_handle, uint8_t * uuid128){
565     // @format HZ
566     uint8_t packet[22];
567     packet[0] = GATT_EVENT_ALL_CHARACTERISTIC_DESCRIPTORS_QUERY_RESULT;
568     packet[1] = sizeof(packet) - 2u;
569     little_endian_store_16(packet, 2, gatt_client->con_handle);
570     ///
571     little_endian_store_16(packet, 4,  descriptor_handle);
572     reverse_128(uuid128, &packet[6]);
573     emit_event_new(gatt_client->callback, packet, sizeof(packet));
574 }
575 
576 static void emit_gatt_mtu_exchanged_result_event(gatt_client_t * gatt_client, uint16_t new_mtu){
577     // @format H2
578     uint8_t packet[6];
579     packet[0] = GATT_EVENT_MTU;
580     packet[1] = sizeof(packet) - 2u;
581     little_endian_store_16(packet, 2, gatt_client->con_handle);
582     little_endian_store_16(packet, 4, new_mtu);
583     att_dispatch_client_mtu_exchanged(gatt_client->con_handle, new_mtu);
584     emit_event_new(gatt_client->callback, packet, sizeof(packet));
585 }
586 ///
587 static void report_gatt_services(gatt_client_t * gatt_client, uint8_t * packet, uint16_t size){
588     uint8_t attr_length = packet[1];
589     uint8_t uuid_length = attr_length - 4u;
590 
591     int i;
592     for (i = 2; i < size; i += attr_length){
593         uint16_t start_group_handle = little_endian_read_16(packet,i);
594         uint16_t end_group_handle   = little_endian_read_16(packet,i+2);
595         uint8_t  uuid128[16];
596         uint16_t uuid16 = 0;
597 
598         if (uuid_length == 2u){
599             uuid16 = little_endian_read_16(packet, i+4);
600             uuid_add_bluetooth_prefix((uint8_t*) &uuid128, uuid16);
601         } else {
602             reverse_128(&packet[i+4], uuid128);
603         }
604         emit_gatt_service_query_result_event(gatt_client, start_group_handle, end_group_handle, uuid128);
605     }
606 }
607 
608 // helper
609 static void 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){
610     uint8_t uuid128[16];
611     uint16_t uuid16 = 0;
612     if (uuid_length == 2u){
613         uuid16 = little_endian_read_16(uuid, 0);
614         uuid_add_bluetooth_prefix((uint8_t*) uuid128, uuid16);
615     } else if (uuid_length == 16u){
616         reverse_128(uuid, uuid128);
617     } else {
618         return;
619     }
620 
621     if (gatt_client->filter_with_uuid && (memcmp(gatt_client->uuid128, uuid128, 16) != 0)) return;
622 
623     gatt_client->characteristic_properties = properties;
624     gatt_client->characteristic_start_handle = start_handle;
625     gatt_client->attribute_handle = value_handle;
626 
627     if (gatt_client->filter_with_uuid) return;
628 
629     gatt_client->uuid16 = uuid16;
630     (void)memcpy(gatt_client->uuid128, uuid128, 16);
631 }
632 
633 static void characteristic_end_found(gatt_client_t * gatt_client, uint16_t end_handle){
634     // TODO: stop searching if filter and uuid found
635 
636     if (!gatt_client->characteristic_start_handle) return;
637 
638     emit_gatt_characteristic_query_result_event(gatt_client, gatt_client->characteristic_start_handle, gatt_client->attribute_handle,
639                                                 end_handle, gatt_client->characteristic_properties, gatt_client->uuid128);
640 
641     gatt_client->characteristic_start_handle = 0;
642 }
643 
644 static void report_gatt_characteristics(gatt_client_t * gatt_client, uint8_t * packet, uint16_t size){
645     if (size < 2u) return;
646     uint8_t attr_length = packet[1];
647     if ((attr_length != 7u) && (attr_length != 21u)) return;
648     uint8_t uuid_length = attr_length - 5u;
649     int i;
650     for (i = 2u; (i + attr_length) <= size; i += attr_length){
651         uint16_t start_handle = little_endian_read_16(packet, i);
652         uint8_t  properties = packet[i+2];
653         uint16_t value_handle = little_endian_read_16(packet, i+3);
654         characteristic_end_found(gatt_client, start_handle - 1u);
655         characteristic_start_found(gatt_client, start_handle, properties, value_handle, &packet[i + 5], uuid_length);
656     }
657 }
658 
659 static void report_gatt_included_service_uuid16(gatt_client_t * gatt_client, uint16_t include_handle, uint16_t uuid16){
660     uint8_t normalized_uuid128[16];
661     uuid_add_bluetooth_prefix(normalized_uuid128, uuid16);
662     emit_gatt_included_service_query_result_event(gatt_client, include_handle, gatt_client->query_start_handle,
663                                                   gatt_client->query_end_handle, normalized_uuid128);
664 }
665 
666 static void report_gatt_included_service_uuid128(gatt_client_t * gatt_client, uint16_t include_handle, uint8_t *uuid128){
667     emit_gatt_included_service_query_result_event(gatt_client, include_handle, gatt_client->query_start_handle,
668                                                   gatt_client->query_end_handle, uuid128);
669 }
670 
671 // @returns packet pointer
672 // @note assume that value is part of an l2cap buffer - overwrite HCI + L2CAP packet headers
673 static const int characteristic_value_event_header_size = 8;
674 static uint8_t * setup_characteristic_value_packet(uint8_t type, hci_con_handle_t con_handle, uint16_t attribute_handle, uint8_t * value, uint16_t length){
675 #ifdef FUZZING_BUILD_MODE_UNSAFE_FOR_PRODUCTION
676     // avoid using pre ATT headers.
677     return NULL;
678 #endif
679     // before the value inside the ATT PDU
680     uint8_t * packet = value - characteristic_value_event_header_size;
681     packet[0] = type;
682     packet[1] = characteristic_value_event_header_size - 2 + length;
683     little_endian_store_16(packet, 2, con_handle);
684     little_endian_store_16(packet, 4, attribute_handle);
685     little_endian_store_16(packet, 6, length);
686     return packet;
687 }
688 
689 // @returns packet pointer
690 // @note assume that value is part of an l2cap buffer - overwrite parts of the HCI/L2CAP/ATT packet (4/4/3) bytes
691 static const int long_characteristic_value_event_header_size = 10;
692 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){
693 #ifdef FUZZING_BUILD_MODE_UNSAFE_FOR_PRODUCTION
694     // avoid using pre ATT headers.
695     return NULL;
696 #endif
697 #if defined(HCI_INCOMING_PRE_BUFFER_SIZE) && (HCI_INCOMING_PRE_BUFFER_SIZE >= 10 - 8) // L2CAP Header (4) - ACL Header (4)
698     // before the value inside the ATT PDU
699     uint8_t * packet = value - long_characteristic_value_event_header_size;
700     packet[0] = type;
701     packet[1] = long_characteristic_value_event_header_size - 2 + length;
702     little_endian_store_16(packet, 2, con_handle);
703     little_endian_store_16(packet, 4, attribute_handle);
704     little_endian_store_16(packet, 6, offset);
705     little_endian_store_16(packet, 8, length);
706     return packet;
707 #else
708     log_error("HCI_INCOMING_PRE_BUFFER_SIZE >= 2 required for long characteristic reads");
709     return NULL;
710 #endif
711 }
712 
713 // test if notification/indication should be delivered to application (BLESA)
714 static bool gatt_client_accept_server_message(hci_con_handle_t con_handle){
715 #ifdef ENABLE_LE_PROACTIVE_AUTHENTICATION
716 	// ignore messages until re-encryption is complete
717     if (gap_reconnect_security_setup_active(con_handle)) return false;
718 
719 	// after that ignore if bonded but not encrypted
720 	return !gap_bonded(con_handle) || (gap_encryption_key_size(con_handle) > 0);
721 #else
722 	return true;
723 #endif
724 }
725 
726 
727 // @note assume that value is part of an l2cap buffer - overwrite parts of the HCI/L2CAP/ATT packet (4/4/3) bytes
728 static void report_gatt_notification(hci_con_handle_t con_handle, uint16_t value_handle, uint8_t * value, int length){
729 	if (!gatt_client_accept_server_message(con_handle)) return;
730     uint8_t * packet = setup_characteristic_value_packet(GATT_EVENT_NOTIFICATION, con_handle, value_handle, value, length);
731     emit_event_to_registered_listeners(con_handle, value_handle, packet, characteristic_value_event_header_size + length);
732 }
733 
734 // @note assume that value is part of an l2cap buffer - overwrite parts of the HCI/L2CAP/ATT packet (4/4/3) bytes
735 static void report_gatt_indication(hci_con_handle_t con_handle, uint16_t value_handle, uint8_t * value, int length){
736 	if (!gatt_client_accept_server_message(con_handle)) return;
737     uint8_t * packet = setup_characteristic_value_packet(GATT_EVENT_INDICATION, con_handle, value_handle, value, length);
738     emit_event_to_registered_listeners(con_handle, value_handle, packet, characteristic_value_event_header_size + length);
739 }
740 
741 // @note assume that value is part of an l2cap buffer - overwrite parts of the HCI/L2CAP/ATT packet (4/4/3) bytes
742 static void report_gatt_characteristic_value(gatt_client_t * gatt_client, uint16_t attribute_handle, uint8_t * value, uint16_t length){
743     uint8_t * packet = setup_characteristic_value_packet(GATT_EVENT_CHARACTERISTIC_VALUE_QUERY_RESULT, gatt_client->con_handle, attribute_handle, value, length);
744     emit_event_new(gatt_client->callback, packet, characteristic_value_event_header_size + length);
745 }
746 
747 // @note assume that value is part of an l2cap buffer - overwrite parts of the HCI/L2CAP/ATT packet (4/4/3) bytes
748 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){
749     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);
750     if (!packet) return;
751     emit_event_new(gatt_client->callback, packet, blob_length + long_characteristic_value_event_header_size);
752 }
753 
754 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){
755     UNUSED(value_offset);
756     uint8_t * packet = setup_characteristic_value_packet(GATT_EVENT_CHARACTERISTIC_DESCRIPTOR_QUERY_RESULT, gatt_client->con_handle, descriptor_handle, value, value_length);
757     emit_event_new(gatt_client->callback, packet, value_length + 8u);
758 }
759 
760 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){
761     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);
762     if (!packet) return;
763     emit_event_new(gatt_client->callback, packet, blob_length + long_characteristic_value_event_header_size);
764 }
765 
766 static void report_gatt_all_characteristic_descriptors(gatt_client_t * gatt_client, uint8_t * packet, uint16_t size, uint16_t pair_size){
767     int i;
768     for (i = 0u; (i + pair_size) <= size; i += pair_size){
769         uint16_t descriptor_handle = little_endian_read_16(packet,i);
770         uint8_t uuid128[16];
771         uint16_t uuid16 = 0;
772         if (pair_size == 4u){
773             uuid16 = little_endian_read_16(packet,i+2);
774             uuid_add_bluetooth_prefix(uuid128, uuid16);
775         } else {
776             reverse_128(&packet[i+2], uuid128);
777         }
778         emit_gatt_all_characteristic_descriptors_result_event(gatt_client, descriptor_handle, uuid128);
779     }
780 
781 }
782 
783 static int is_query_done(gatt_client_t * gatt_client, uint16_t last_result_handle){
784     return last_result_handle >= gatt_client->end_group_handle;
785 }
786 
787 static void trigger_next_query(gatt_client_t * gatt_client, uint16_t last_result_handle, gatt_client_state_t next_query_state){
788     if (is_query_done(gatt_client, last_result_handle)){
789         gatt_client_handle_transaction_complete(gatt_client);
790         emit_gatt_complete_event(gatt_client, ATT_ERROR_SUCCESS);
791         return;
792     }
793     // next
794     gatt_client->start_group_handle = last_result_handle + 1u;
795     gatt_client->gatt_client_state = next_query_state;
796 }
797 
798 static void trigger_next_included_service_query(gatt_client_t * gatt_client, uint16_t last_result_handle){
799     trigger_next_query(gatt_client, last_result_handle, P_W2_SEND_INCLUDED_SERVICE_QUERY);
800 }
801 
802 static void trigger_next_service_query(gatt_client_t * gatt_client, uint16_t last_result_handle){
803     trigger_next_query(gatt_client, last_result_handle, P_W2_SEND_SERVICE_QUERY);
804 }
805 
806 static void trigger_next_service_by_uuid_query(gatt_client_t * gatt_client, uint16_t last_result_handle){
807     trigger_next_query(gatt_client, last_result_handle, P_W2_SEND_SERVICE_WITH_UUID_QUERY);
808 }
809 
810 static void trigger_next_characteristic_query(gatt_client_t * gatt_client, uint16_t last_result_handle){
811     if (is_query_done(gatt_client, last_result_handle)){
812         // report last characteristic
813         characteristic_end_found(gatt_client, gatt_client->end_group_handle);
814     }
815     trigger_next_query(gatt_client, last_result_handle, P_W2_SEND_ALL_CHARACTERISTICS_OF_SERVICE_QUERY);
816 }
817 
818 static void trigger_next_characteristic_descriptor_query(gatt_client_t * gatt_client, uint16_t last_result_handle){
819     trigger_next_query(gatt_client, last_result_handle, P_W2_SEND_ALL_CHARACTERISTIC_DESCRIPTORS_QUERY);
820 }
821 
822 static void trigger_next_read_by_type_query(gatt_client_t * gatt_client, uint16_t last_result_handle){
823     trigger_next_query(gatt_client, last_result_handle, P_W2_SEND_READ_BY_TYPE_REQUEST);
824 }
825 
826 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){
827     gatt_client->attribute_offset += write_blob_length(gatt_client);
828     uint16_t next_blob_length =  write_blob_length(gatt_client);
829 
830     if (next_blob_length == 0u){
831         gatt_client->gatt_client_state = done_state;
832         return;
833     }
834     gatt_client->gatt_client_state = next_query_state;
835 }
836 
837 static void trigger_next_blob_query(gatt_client_t * gatt_client, gatt_client_state_t next_query_state, uint16_t received_blob_length){
838 
839     uint16_t max_blob_length = gatt_client->mtu - 1u;
840     if (received_blob_length < max_blob_length){
841         gatt_client_handle_transaction_complete(gatt_client);
842         emit_gatt_complete_event(gatt_client, ATT_ERROR_SUCCESS);
843         return;
844     }
845 
846     gatt_client->attribute_offset += received_blob_length;
847     gatt_client->gatt_client_state = next_query_state;
848 }
849 
850 
851 static int is_value_valid(gatt_client_t *gatt_client, uint8_t *packet, uint16_t size){
852     uint16_t attribute_handle = little_endian_read_16(packet, 1);
853     uint16_t value_offset = little_endian_read_16(packet, 3);
854 
855     if (gatt_client->attribute_handle != attribute_handle) return 0;
856     if (gatt_client->attribute_offset != value_offset) return 0;
857     return memcmp(&gatt_client->attribute_value[gatt_client->attribute_offset], &packet[5], size - 5u) == 0u;
858 }
859 
860 // returns 1 if packet was sent
861 static int gatt_client_run_for_gatt_client(gatt_client_t * gatt_client){
862 
863     // wait until re-encryption as central is complete
864     if (gap_reconnect_security_setup_active(gatt_client->con_handle)) return 0;
865 
866 #ifdef ENABLE_GATT_CLIENT_PAIRING
867     // wait until pairing complete
868     if (gatt_client->wait_for_pairing_complete) return 0;
869 #endif
870 
871     switch (gatt_client->mtu_state) {
872         case SEND_MTU_EXCHANGE:
873             gatt_client->mtu_state = SENT_MTU_EXCHANGE;
874             att_exchange_mtu_request(gatt_client->con_handle);
875             return 1;
876         case SENT_MTU_EXCHANGE:
877             return 0;
878         default:
879             break;
880     }
881 
882     if (gatt_client->send_confirmation){
883         gatt_client->send_confirmation = 0;
884         att_confirmation(gatt_client->con_handle);
885         return 1;
886     }
887 
888     // check MTU for writes
889     switch (gatt_client->gatt_client_state){
890         case P_W2_SEND_WRITE_CHARACTERISTIC_VALUE:
891         case P_W2_SEND_WRITE_CHARACTERISTIC_DESCRIPTOR:
892             if (gatt_client->attribute_length <= (gatt_client->mtu - 3u)) break;
893             log_error("gatt_client_run: value len %u > MTU %u - 3\n", gatt_client->attribute_length,gatt_client->mtu);
894             gatt_client_handle_transaction_complete(gatt_client);
895             emit_gatt_complete_event(gatt_client, ATT_ERROR_INVALID_ATTRIBUTE_VALUE_LENGTH);
896             return 0;
897         default:
898             break;
899     }
900 
901     switch (gatt_client->gatt_client_state){
902         case P_W2_SEND_SERVICE_QUERY:
903             gatt_client->gatt_client_state = P_W4_SERVICE_QUERY_RESULT;
904             send_gatt_services_request(gatt_client);
905             return 1;
906 
907         case P_W2_SEND_SERVICE_WITH_UUID_QUERY:
908             gatt_client->gatt_client_state = P_W4_SERVICE_WITH_UUID_RESULT;
909             send_gatt_services_by_uuid_request(gatt_client);
910             return 1;
911 
912         case P_W2_SEND_ALL_CHARACTERISTICS_OF_SERVICE_QUERY:
913             gatt_client->gatt_client_state = P_W4_ALL_CHARACTERISTICS_OF_SERVICE_QUERY_RESULT;
914             send_gatt_characteristic_request(gatt_client);
915             return 1;
916 
917         case P_W2_SEND_CHARACTERISTIC_WITH_UUID_QUERY:
918             gatt_client->gatt_client_state = P_W4_CHARACTERISTIC_WITH_UUID_QUERY_RESULT;
919             send_gatt_characteristic_request(gatt_client);
920             return 1;
921 
922         case P_W2_SEND_ALL_CHARACTERISTIC_DESCRIPTORS_QUERY:
923             gatt_client->gatt_client_state = P_W4_CHARACTERISTIC_WITH_UUID_QUERY_RESULT;
924             send_gatt_characteristic_descriptor_request(gatt_client);
925             return 1;
926 
927         case P_W2_SEND_INCLUDED_SERVICE_QUERY:
928             gatt_client->gatt_client_state = P_W4_INCLUDED_SERVICE_QUERY_RESULT;
929             send_gatt_included_service_request(gatt_client);
930             return 1;
931 
932         case P_W2_SEND_INCLUDED_SERVICE_WITH_UUID_QUERY:
933             gatt_client->gatt_client_state = P_W4_INCLUDED_SERVICE_UUID_WITH_QUERY_RESULT;
934             send_gatt_included_service_uuid_request(gatt_client);
935             return 1;
936 
937         case P_W2_SEND_READ_CHARACTERISTIC_VALUE_QUERY:
938             gatt_client->gatt_client_state = P_W4_READ_CHARACTERISTIC_VALUE_RESULT;
939             send_gatt_read_characteristic_value_request(gatt_client);
940             return 1;
941 
942         case P_W2_SEND_READ_BLOB_QUERY:
943             gatt_client->gatt_client_state = P_W4_READ_BLOB_RESULT;
944             send_gatt_read_blob_request(gatt_client);
945             return 1;
946 
947         case P_W2_SEND_READ_BY_TYPE_REQUEST:
948             gatt_client->gatt_client_state = P_W4_READ_BY_TYPE_RESPONSE;
949             send_gatt_read_by_type_request(gatt_client);
950             return 1;
951 
952         case P_W2_SEND_READ_MULTIPLE_REQUEST:
953             gatt_client->gatt_client_state = P_W4_READ_MULTIPLE_RESPONSE;
954             send_gatt_read_multiple_request(gatt_client);
955             return 1;
956 
957         case P_W2_SEND_WRITE_CHARACTERISTIC_VALUE:
958             gatt_client->gatt_client_state = P_W4_WRITE_CHARACTERISTIC_VALUE_RESULT;
959             send_gatt_write_attribute_value_request(gatt_client);
960             return 1;
961 
962         case P_W2_PREPARE_WRITE:
963             gatt_client->gatt_client_state = P_W4_PREPARE_WRITE_RESULT;
964             send_gatt_prepare_write_request(gatt_client);
965             return 1;
966 
967         case P_W2_PREPARE_WRITE_SINGLE:
968             gatt_client->gatt_client_state = P_W4_PREPARE_WRITE_SINGLE_RESULT;
969             send_gatt_prepare_write_request(gatt_client);
970             return 1;
971 
972         case P_W2_PREPARE_RELIABLE_WRITE:
973             gatt_client->gatt_client_state = P_W4_PREPARE_RELIABLE_WRITE_RESULT;
974             send_gatt_prepare_write_request(gatt_client);
975             return 1;
976 
977         case P_W2_EXECUTE_PREPARED_WRITE:
978             gatt_client->gatt_client_state = P_W4_EXECUTE_PREPARED_WRITE_RESULT;
979             send_gatt_execute_write_request(gatt_client);
980             return 1;
981 
982         case P_W2_CANCEL_PREPARED_WRITE:
983             gatt_client->gatt_client_state = P_W4_CANCEL_PREPARED_WRITE_RESULT;
984             send_gatt_cancel_prepared_write_request(gatt_client);
985             return 1;
986 
987         case P_W2_CANCEL_PREPARED_WRITE_DATA_MISMATCH:
988             gatt_client->gatt_client_state = P_W4_CANCEL_PREPARED_WRITE_DATA_MISMATCH_RESULT;
989             send_gatt_cancel_prepared_write_request(gatt_client);
990             return 1;
991 
992 #ifdef ENABLE_GATT_FIND_INFORMATION_FOR_CCC_DISCOVERY
993         case P_W2_SEND_FIND_CLIENT_CHARACTERISTIC_CONFIGURATION_QUERY:
994             // use Find Information
995             gatt_client->gatt_client_state = P_W4_FIND_CLIENT_CHARACTERISTIC_CONFIGURATION_QUERY_RESULT;
996             send_gatt_characteristic_descriptor_request(gatt_client);
997 #else
998         case P_W2_SEND_READ_CLIENT_CHARACTERISTIC_CONFIGURATION_QUERY:
999             // Use Read By Type
1000             gatt_client->gatt_client_state = P_W4_READ_CLIENT_CHARACTERISTIC_CONFIGURATION_QUERY_RESULT;
1001             send_gatt_read_client_characteristic_configuration_request(gatt_client);
1002 #endif
1003             return 1;
1004 
1005         case P_W2_SEND_READ_CHARACTERISTIC_DESCRIPTOR_QUERY:
1006             gatt_client->gatt_client_state = P_W4_READ_CHARACTERISTIC_DESCRIPTOR_RESULT;
1007             send_gatt_read_characteristic_descriptor_request(gatt_client);
1008             return 1;
1009 
1010         case P_W2_SEND_READ_BLOB_CHARACTERISTIC_DESCRIPTOR_QUERY:
1011             gatt_client->gatt_client_state = P_W4_READ_BLOB_CHARACTERISTIC_DESCRIPTOR_RESULT;
1012             send_gatt_read_blob_request(gatt_client);
1013             return 1;
1014 
1015         case P_W2_SEND_WRITE_CHARACTERISTIC_DESCRIPTOR:
1016             gatt_client->gatt_client_state = P_W4_WRITE_CHARACTERISTIC_DESCRIPTOR_RESULT;
1017             send_gatt_write_attribute_value_request(gatt_client);
1018             return 1;
1019 
1020         case P_W2_WRITE_CLIENT_CHARACTERISTIC_CONFIGURATION:
1021             gatt_client->gatt_client_state = P_W4_CLIENT_CHARACTERISTIC_CONFIGURATION_RESULT;
1022             send_gatt_write_client_characteristic_configuration_request(gatt_client);
1023             return 1;
1024 
1025         case P_W2_PREPARE_WRITE_CHARACTERISTIC_DESCRIPTOR:
1026             gatt_client->gatt_client_state = P_W4_PREPARE_WRITE_CHARACTERISTIC_DESCRIPTOR_RESULT;
1027             send_gatt_prepare_write_request(gatt_client);
1028             return 1;
1029 
1030         case P_W2_EXECUTE_PREPARED_WRITE_CHARACTERISTIC_DESCRIPTOR:
1031             gatt_client->gatt_client_state = P_W4_EXECUTE_PREPARED_WRITE_CHARACTERISTIC_DESCRIPTOR_RESULT;
1032             send_gatt_execute_write_request(gatt_client);
1033             return 1;
1034 
1035 #ifdef ENABLE_LE_SIGNED_WRITE
1036         case P_W4_IDENTITY_RESOLVING:
1037             log_info("P_W4_IDENTITY_RESOLVING - state %x", sm_identity_resolving_state(gatt_client->con_handle));
1038             switch (sm_identity_resolving_state(gatt_client->con_handle)){
1039                 case IRK_LOOKUP_SUCCEEDED:
1040                     gatt_client->le_device_index = sm_le_device_index(gatt_client->con_handle);
1041                     gatt_client->gatt_client_state = P_W4_CMAC_READY;
1042                     break;
1043                 case IRK_LOOKUP_FAILED:
1044                     gatt_client_handle_transaction_complete(gatt_client);
1045                     emit_gatt_complete_event(gatt_client, ATT_ERROR_BONDING_INFORMATION_MISSING);
1046                     return 0;
1047                 default:
1048                     return 0;
1049             }
1050 
1051             /* Fall through */
1052 
1053         case P_W4_CMAC_READY:
1054             if (sm_cmac_ready()){
1055                 sm_key_t csrk;
1056                 le_device_db_local_csrk_get(gatt_client->le_device_index, csrk);
1057                 uint32_t sign_counter = le_device_db_local_counter_get(gatt_client->le_device_index);
1058                 gatt_client->gatt_client_state = P_W4_CMAC_RESULT;
1059                 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);
1060             }
1061             return 0;
1062 
1063         case P_W2_SEND_SIGNED_WRITE: {
1064             gatt_client->gatt_client_state = P_W4_SEND_SINGED_WRITE_DONE;
1065             // bump local signing counter
1066             uint32_t sign_counter = le_device_db_local_counter_get(gatt_client->le_device_index);
1067             le_device_db_local_counter_set(gatt_client->le_device_index, sign_counter + 1);
1068             // send signed write command
1069             send_gatt_signed_write_request(gatt_client, sign_counter);
1070             // finally, notifiy client that write is complete
1071             gatt_client_handle_transaction_complete(gatt_client);
1072             emit_gatt_complete_event(gatt_client, ATT_ERROR_SUCCESS);
1073             return 1;
1074         }
1075 #endif
1076         default:
1077             break;
1078     }
1079 
1080     // requested can send snow?
1081     if (gatt_client->write_without_response_callback){
1082         btstack_packet_handler_t packet_handler = gatt_client->write_without_response_callback;
1083         gatt_client->write_without_response_callback = NULL;
1084         uint8_t event[4];
1085         event[0] = GATT_EVENT_CAN_WRITE_WITHOUT_RESPONSE;
1086         event[1] = sizeof(event) - 2u;
1087         little_endian_store_16(event, 2, gatt_client->con_handle);
1088         packet_handler(HCI_EVENT_PACKET, gatt_client->con_handle, event, sizeof(event));
1089         return 1; // to trigger requeueing (even if higher layer didn't sent)
1090     }
1091 
1092     return 0;
1093 }
1094 
1095 static void gatt_client_run(void){
1096     btstack_linked_item_t *it;
1097     for (it = (btstack_linked_item_t *) gatt_client_connections; it != NULL; it = it->next){
1098         gatt_client_t * gatt_client = (gatt_client_t *) it;
1099         if (!att_dispatch_client_can_send_now(gatt_client->con_handle)) {
1100             att_dispatch_client_request_can_send_now_event(gatt_client->con_handle);
1101             return;
1102         }
1103         int packet_sent = gatt_client_run_for_gatt_client(gatt_client);
1104         if (packet_sent){
1105             // request new permission
1106             att_dispatch_client_request_can_send_now_event(gatt_client->con_handle);
1107             // requeue client for fairness and exit
1108             // note: iterator has become invalid
1109             btstack_linked_list_remove(&gatt_client_connections, (btstack_linked_item_t *) gatt_client);
1110             btstack_linked_list_add_tail(&gatt_client_connections, (btstack_linked_item_t *) gatt_client);
1111             return;
1112         }
1113     }
1114 }
1115 
1116 static void gatt_client_report_error_if_pending(gatt_client_t *gatt_client, uint8_t att_error_code) {
1117     if (is_ready(gatt_client) == 1) return;
1118     gatt_client_handle_transaction_complete(gatt_client);
1119     emit_gatt_complete_event(gatt_client, att_error_code);
1120 }
1121 
1122 static void gatt_client_event_packet_handler(uint8_t packet_type, uint16_t channel, uint8_t *packet, uint16_t size){
1123     UNUSED(channel);    // ok: handling own l2cap events
1124     UNUSED(size);       // ok: there is no channel
1125 
1126     if (packet_type != HCI_EVENT_PACKET) return;
1127 
1128     hci_con_handle_t con_handle;
1129     gatt_client_t * gatt_client;
1130     switch (hci_event_packet_get_type(packet)) {
1131         case HCI_EVENT_DISCONNECTION_COMPLETE:
1132             log_info("GATT Client: HCI_EVENT_DISCONNECTION_COMPLETE");
1133             con_handle = little_endian_read_16(packet,3);
1134             gatt_client = gatt_client_get_context_for_handle(con_handle);
1135             if (gatt_client == NULL) break;
1136 
1137             gatt_client_report_error_if_pending(gatt_client, ATT_ERROR_HCI_DISCONNECT_RECEIVED);
1138             gatt_client_timeout_stop(gatt_client);
1139             btstack_linked_list_remove(&gatt_client_connections, (btstack_linked_item_t *) gatt_client);
1140             btstack_memory_gatt_client_free(gatt_client);
1141             break;
1142 
1143 #ifdef ENABLE_GATT_CLIENT_PAIRING
1144         // Pairing complete (with/without bonding=storing of pairing information)
1145         case SM_EVENT_PAIRING_COMPLETE:
1146             con_handle = sm_event_pairing_complete_get_handle(packet);
1147             gatt_client = gatt_client_get_context_for_handle(con_handle);
1148             if (gatt_client == NULL) break;
1149 
1150             if (gatt_client->wait_for_pairing_complete){
1151                 gatt_client->wait_for_pairing_complete = 0;
1152                 if (sm_event_pairing_complete_get_status(packet)){
1153                     log_info("pairing failed, report previous error 0x%x", gatt_client->pending_error_code);
1154                     gatt_client_report_error_if_pending(gatt_client, gatt_client->pending_error_code);
1155                 } else {
1156                     log_info("pairing success, retry operation");
1157                 }
1158             }
1159             break;
1160 #endif
1161 #ifdef ENABLE_LE_SIGNED_WRITE
1162         // Identity Resolving completed (no code, gatt_client_run will continue)
1163         case SM_EVENT_IDENTITY_RESOLVING_SUCCEEDED:
1164         case SM_EVENT_IDENTITY_RESOLVING_FAILED:
1165             break;
1166 #endif
1167 #ifdef ENABLE_LE_PROACTIVE_AUTHENTICATION
1168         // re-encryption complete
1169         case SM_EVENT_REENCRYPTION_COMPLETE:
1170             con_handle = sm_event_reencryption_complete_get_handle(packet);
1171             gatt_client = gatt_client_get_context_for_handle(con_handle);
1172             if (gatt_client == NULL) break;
1173 
1174             // report bonding information missing, if re-encryption failed
1175             if (sm_event_reencryption_complete_get_status(packet)){
1176                 gatt_client_report_error_if_pending(gatt_client, ATT_ERROR_BONDING_INFORMATION_MISSING);
1177             } else {
1178                 log_info("re-encryption success, retry operation");
1179             }
1180             break;
1181 #endif
1182         default:
1183             break;
1184     }
1185 
1186     gatt_client_run();
1187 }
1188 
1189 static void gatt_client_att_packet_handler(uint8_t packet_type, uint16_t handle, uint8_t *packet, uint16_t size){
1190     gatt_client_t * gatt_client;
1191     if (size < 1u) return;
1192 
1193     if (packet_type == HCI_EVENT_PACKET) {
1194         switch (packet[0]){
1195             case L2CAP_EVENT_CAN_SEND_NOW:
1196                 gatt_client_run();
1197                 break;
1198             // att_server has negotiated the mtu for this connection, cache if context exists
1199             case ATT_EVENT_MTU_EXCHANGE_COMPLETE:
1200                 if (size < 6u) break;
1201                 gatt_client = gatt_client_get_context_for_handle(handle);
1202                 if (gatt_client == NULL) break;
1203                 gatt_client->mtu = little_endian_read_16(packet, 4);
1204                 break;
1205             default:
1206                 break;
1207         }
1208         return;
1209     }
1210 
1211     if (packet_type != ATT_DATA_PACKET) return;
1212 
1213     // special cases: notifications don't need a context while indications motivate creating one
1214     switch (packet[0]){
1215         case ATT_HANDLE_VALUE_NOTIFICATION:
1216             if (size < 3u) return;
1217             report_gatt_notification(handle, little_endian_read_16(packet,1u), &packet[3], size-3u);
1218             return;
1219         case ATT_HANDLE_VALUE_INDICATION:
1220             gatt_client = gatt_client_provide_context_for_handle(handle);
1221             break;
1222         default:
1223             gatt_client = gatt_client_get_context_for_handle(handle);
1224             break;
1225     }
1226 
1227     if (gatt_client == NULL) return;
1228 
1229     uint8_t error_code;
1230     switch (packet[0]){
1231         case ATT_EXCHANGE_MTU_RESPONSE:
1232         {
1233             if (size < 3u) break;
1234             uint16_t remote_rx_mtu = little_endian_read_16(packet, 1);
1235             uint16_t local_rx_mtu = l2cap_max_le_mtu();
1236             gatt_client->mtu = (remote_rx_mtu < local_rx_mtu) ? remote_rx_mtu : local_rx_mtu;
1237             gatt_client->mtu_state = MTU_EXCHANGED;
1238             emit_gatt_mtu_exchanged_result_event(gatt_client, gatt_client->mtu);
1239             break;
1240         }
1241         case ATT_READ_BY_GROUP_TYPE_RESPONSE:
1242             switch(gatt_client->gatt_client_state){
1243                 case P_W4_SERVICE_QUERY_RESULT:
1244                     report_gatt_services(gatt_client, packet, size);
1245                     trigger_next_service_query(gatt_client, get_last_result_handle_from_service_list(packet, size));
1246                     // GATT_EVENT_QUERY_COMPLETE is emitted by trigger_next_xxx when done
1247                     break;
1248                 default:
1249                     break;
1250             }
1251             break;
1252         case ATT_HANDLE_VALUE_INDICATION:
1253             if (size < 3u) break;
1254             report_gatt_indication(handle, little_endian_read_16(packet,1u), &packet[3], size-3u);
1255             gatt_client->send_confirmation = 1;
1256             break;
1257 
1258         case ATT_READ_BY_TYPE_RESPONSE:
1259             switch (gatt_client->gatt_client_state){
1260                 case P_W4_ALL_CHARACTERISTICS_OF_SERVICE_QUERY_RESULT:
1261                     report_gatt_characteristics(gatt_client, packet, size);
1262                     trigger_next_characteristic_query(gatt_client, get_last_result_handle_from_characteristics_list(packet, size));
1263                     // GATT_EVENT_QUERY_COMPLETE is emitted by trigger_next_xxx when done, or by ATT_ERROR
1264                     break;
1265                 case P_W4_CHARACTERISTIC_WITH_UUID_QUERY_RESULT:
1266                     report_gatt_characteristics(gatt_client, packet, size);
1267                     trigger_next_characteristic_query(gatt_client, get_last_result_handle_from_characteristics_list(packet, size));
1268                     // GATT_EVENT_QUERY_COMPLETE is emitted by trigger_next_xxx when done, or by ATT_ERROR
1269                     break;
1270                 case P_W4_INCLUDED_SERVICE_QUERY_RESULT:
1271                 {
1272                     if (size < 2u) break;
1273                     uint16_t uuid16 = 0;
1274                     uint16_t pair_size = packet[1];
1275 
1276                     if (pair_size == 6u){
1277                         if (size < 8u) break;
1278                         // UUIDs not available, query first included service
1279                         gatt_client->start_group_handle = little_endian_read_16(packet, 2); // ready for next query
1280                         gatt_client->query_start_handle = little_endian_read_16(packet, 4);
1281                         gatt_client->query_end_handle = little_endian_read_16(packet, 6);
1282                         gatt_client->gatt_client_state = P_W2_SEND_INCLUDED_SERVICE_WITH_UUID_QUERY;
1283                         break;
1284                     }
1285 
1286                     if (pair_size != 8u) break;
1287 
1288                     // UUIDs included, report all of them
1289                     uint16_t offset;
1290                     for (offset = 2u; (offset + 8u) <= size; offset += pair_size){
1291                         uint16_t include_handle = little_endian_read_16(packet, offset);
1292                         gatt_client->query_start_handle = little_endian_read_16(packet, offset + 2u);
1293                         gatt_client->query_end_handle = little_endian_read_16(packet, offset + 4u);
1294                         uuid16 = little_endian_read_16(packet, offset+6u);
1295                         report_gatt_included_service_uuid16(gatt_client, include_handle, uuid16);
1296                     }
1297 
1298                     trigger_next_included_service_query(gatt_client, get_last_result_handle_from_included_services_list(packet, size));
1299                     // GATT_EVENT_QUERY_COMPLETE is emitted by trigger_next_xxx when done
1300                     break;
1301                 }
1302 #ifndef ENABLE_GATT_FIND_INFORMATION_FOR_CCC_DISCOVERY
1303                 case P_W4_READ_CLIENT_CHARACTERISTIC_CONFIGURATION_QUERY_RESULT:
1304                     gatt_client->client_characteristic_configuration_handle = little_endian_read_16(packet, 2);
1305                     gatt_client->gatt_client_state = P_W2_WRITE_CLIENT_CHARACTERISTIC_CONFIGURATION;
1306                     break;
1307 #endif
1308                 case P_W4_READ_BY_TYPE_RESPONSE: {
1309                     uint16_t pair_size = packet[1];
1310                     uint16_t offset;
1311                     uint16_t last_result_handle = 0;
1312                     for (offset = 2; offset < size ; offset += pair_size){
1313                         uint16_t value_handle = little_endian_read_16(packet, offset);
1314                         report_gatt_characteristic_value(gatt_client, value_handle, &packet[offset + 2u], pair_size - 2u);
1315                         last_result_handle = value_handle;
1316                     }
1317                     trigger_next_read_by_type_query(gatt_client, last_result_handle);
1318                     break;
1319                 }
1320                 default:
1321                     break;
1322             }
1323             break;
1324         case ATT_READ_RESPONSE:
1325             switch (gatt_client->gatt_client_state){
1326                 case P_W4_INCLUDED_SERVICE_UUID_WITH_QUERY_RESULT: {
1327                     uint8_t uuid128[16];
1328                     reverse_128(&packet[1], uuid128);
1329                     report_gatt_included_service_uuid128(gatt_client, gatt_client->start_group_handle, uuid128);
1330                     trigger_next_included_service_query(gatt_client, gatt_client->start_group_handle);
1331                     // GATT_EVENT_QUERY_COMPLETE is emitted by trigger_next_xxx when done
1332                     break;
1333                 }
1334                 case P_W4_READ_CHARACTERISTIC_VALUE_RESULT:
1335                     gatt_client_handle_transaction_complete(gatt_client);
1336                     report_gatt_characteristic_value(gatt_client, gatt_client->attribute_handle, &packet[1], size - 1u);
1337                     emit_gatt_complete_event(gatt_client, ATT_ERROR_SUCCESS);
1338                     break;
1339 
1340                 case P_W4_READ_CHARACTERISTIC_DESCRIPTOR_RESULT:{
1341                     gatt_client_handle_transaction_complete(gatt_client);
1342                     report_gatt_characteristic_descriptor(gatt_client, gatt_client->attribute_handle, &packet[1], size - 1u, 0u);
1343                     emit_gatt_complete_event(gatt_client, ATT_ERROR_SUCCESS);
1344                     break;
1345                 }
1346                 default:
1347                     break;
1348             }
1349             break;
1350 
1351         case ATT_FIND_BY_TYPE_VALUE_RESPONSE:
1352         {
1353             uint8_t pair_size = 4;
1354             int i;
1355             uint16_t start_group_handle;
1356             uint16_t   end_group_handle= 0xffff; // asserts GATT_EVENT_QUERY_COMPLETE is emitted if no results
1357             for (i = 1u; (i + pair_size) <= size; i += pair_size){
1358                 start_group_handle = little_endian_read_16(packet,i);
1359                 end_group_handle = little_endian_read_16(packet,i+2);
1360                 emit_gatt_service_query_result_event(gatt_client, start_group_handle, end_group_handle, gatt_client->uuid128);
1361             }
1362             trigger_next_service_by_uuid_query(gatt_client, end_group_handle);
1363             // GATT_EVENT_QUERY_COMPLETE is emitted by trigger_next_xxx when done
1364             break;
1365         }
1366         case ATT_FIND_INFORMATION_REPLY:
1367         {
1368             if (size < 2u) break;
1369 
1370             uint8_t pair_size = 4;
1371             if (packet[1u] == 2u){
1372                 pair_size = 18;
1373             }
1374             uint16_t offset = 2;
1375 
1376             if (size < (pair_size + offset)) break;
1377             uint16_t last_descriptor_handle = little_endian_read_16(packet, size - pair_size);
1378 
1379 #ifdef ENABLE_GATT_FIND_INFORMATION_FOR_CCC_DISCOVERY
1380             log_info("ENABLE_GATT_FIND_INFORMATION_FOR_CCC_DISCOVERY, state %x", gatt_client->gatt_client_state);
1381             if (gatt_client->gatt_client_state == P_W4_FIND_CLIENT_CHARACTERISTIC_CONFIGURATION_QUERY_RESULT){
1382                 // iterate over descriptors looking for CCC
1383                 if (pair_size == 4){
1384                     while ((offset + 4) <= size){
1385                         uint16_t uuid16 = little_endian_read_16(packet, offset + 2);
1386                         if (uuid16 == GATT_CLIENT_CHARACTERISTICS_CONFIGURATION){
1387                             gatt_client->client_characteristic_configuration_handle = little_endian_read_16(packet, offset);
1388                             gatt_client->gatt_client_state = P_W2_WRITE_CLIENT_CHARACTERISTIC_CONFIGURATION;
1389                             log_info("CCC found %x", gatt_client->client_characteristic_configuration_handle);
1390                             break;
1391                         }
1392                         offset += pair_size;
1393                     }
1394                 }
1395                 if (is_query_done(gatt_client, last_descriptor_handle)){
1396 
1397                 } else {
1398                     // next
1399                     gatt_client->start_group_handle = last_descriptor_handle + 1;
1400                     gatt_client->gatt_client_state = P_W2_SEND_FIND_CLIENT_CHARACTERISTIC_CONFIGURATION_QUERY;
1401                 }
1402                 break;
1403             }
1404 #endif
1405             report_gatt_all_characteristic_descriptors(gatt_client, &packet[2], size - 2u, pair_size);
1406             trigger_next_characteristic_descriptor_query(gatt_client, last_descriptor_handle);
1407             // GATT_EVENT_QUERY_COMPLETE is emitted by trigger_next_xxx when done
1408             break;
1409         }
1410 
1411         case ATT_WRITE_RESPONSE:
1412             switch (gatt_client->gatt_client_state){
1413                 case P_W4_WRITE_CHARACTERISTIC_VALUE_RESULT:
1414                     gatt_client_handle_transaction_complete(gatt_client);
1415                     emit_gatt_complete_event(gatt_client, ATT_ERROR_SUCCESS);
1416                     break;
1417                 case P_W4_CLIENT_CHARACTERISTIC_CONFIGURATION_RESULT:
1418                     gatt_client_handle_transaction_complete(gatt_client);
1419                     emit_gatt_complete_event(gatt_client, ATT_ERROR_SUCCESS);
1420                     break;
1421                 case P_W4_WRITE_CHARACTERISTIC_DESCRIPTOR_RESULT:
1422                     gatt_client_handle_transaction_complete(gatt_client);
1423                     emit_gatt_complete_event(gatt_client, ATT_ERROR_SUCCESS);
1424                     break;
1425                 default:
1426                     break;
1427             }
1428             break;
1429 
1430         case ATT_READ_BLOB_RESPONSE:{
1431             uint16_t received_blob_length = size-1u;
1432             switch(gatt_client->gatt_client_state){
1433                 case P_W4_READ_BLOB_RESULT:
1434                     report_gatt_long_characteristic_value_blob(gatt_client, gatt_client->attribute_handle, &packet[1], received_blob_length, gatt_client->attribute_offset);
1435                     trigger_next_blob_query(gatt_client, P_W2_SEND_READ_BLOB_QUERY, received_blob_length);
1436                     // GATT_EVENT_QUERY_COMPLETE is emitted by trigger_next_xxx when done
1437                     break;
1438                 case P_W4_READ_BLOB_CHARACTERISTIC_DESCRIPTOR_RESULT:
1439                     report_gatt_long_characteristic_descriptor(gatt_client, gatt_client->attribute_handle,
1440                                                                &packet[1], received_blob_length,
1441                                                                gatt_client->attribute_offset);
1442                     trigger_next_blob_query(gatt_client, P_W2_SEND_READ_BLOB_CHARACTERISTIC_DESCRIPTOR_QUERY, received_blob_length);
1443                     // GATT_EVENT_QUERY_COMPLETE is emitted by trigger_next_xxx when done
1444                     break;
1445                 default:
1446                     break;
1447             }
1448             break;
1449         }
1450         case ATT_PREPARE_WRITE_RESPONSE:
1451             switch (gatt_client->gatt_client_state){
1452                 case P_W4_PREPARE_WRITE_SINGLE_RESULT:
1453                     gatt_client_handle_transaction_complete(gatt_client);
1454                     if (is_value_valid(gatt_client, packet, size)){
1455                         emit_gatt_complete_event(gatt_client, ATT_ERROR_SUCCESS);
1456                     } else {
1457                         emit_gatt_complete_event(gatt_client, ATT_ERROR_DATA_MISMATCH);
1458                     }
1459                     break;
1460 
1461                 case P_W4_PREPARE_WRITE_RESULT:{
1462                     gatt_client->attribute_offset = little_endian_read_16(packet, 3);
1463                     trigger_next_prepare_write_query(gatt_client, P_W2_PREPARE_WRITE, P_W2_EXECUTE_PREPARED_WRITE);
1464                     // GATT_EVENT_QUERY_COMPLETE is emitted by trigger_next_xxx when done
1465                     break;
1466                 }
1467                 case P_W4_PREPARE_WRITE_CHARACTERISTIC_DESCRIPTOR_RESULT:{
1468                     gatt_client->attribute_offset = little_endian_read_16(packet, 3);
1469                     trigger_next_prepare_write_query(gatt_client, P_W2_PREPARE_WRITE_CHARACTERISTIC_DESCRIPTOR, P_W2_EXECUTE_PREPARED_WRITE_CHARACTERISTIC_DESCRIPTOR);
1470                     // GATT_EVENT_QUERY_COMPLETE is emitted by trigger_next_xxx when done
1471                     break;
1472                 }
1473                 case P_W4_PREPARE_RELIABLE_WRITE_RESULT:{
1474                     if (is_value_valid(gatt_client, packet, size)){
1475                         gatt_client->attribute_offset = little_endian_read_16(packet, 3);
1476                         trigger_next_prepare_write_query(gatt_client, P_W2_PREPARE_RELIABLE_WRITE, P_W2_EXECUTE_PREPARED_WRITE);
1477                         // GATT_EVENT_QUERY_COMPLETE is emitted by trigger_next_xxx when done
1478                         break;
1479                     }
1480                     gatt_client->gatt_client_state = P_W2_CANCEL_PREPARED_WRITE_DATA_MISMATCH;
1481                     break;
1482                 }
1483                 default:
1484                     break;
1485             }
1486             break;
1487 
1488         case ATT_EXECUTE_WRITE_RESPONSE:
1489             switch (gatt_client->gatt_client_state){
1490                 case P_W4_EXECUTE_PREPARED_WRITE_RESULT:
1491                     gatt_client_handle_transaction_complete(gatt_client);
1492                     emit_gatt_complete_event(gatt_client, ATT_ERROR_SUCCESS);
1493                     break;
1494                 case P_W4_CANCEL_PREPARED_WRITE_RESULT:
1495                     gatt_client_handle_transaction_complete(gatt_client);
1496                     emit_gatt_complete_event(gatt_client, ATT_ERROR_SUCCESS);
1497                     break;
1498                 case P_W4_CANCEL_PREPARED_WRITE_DATA_MISMATCH_RESULT:
1499                     gatt_client_handle_transaction_complete(gatt_client);
1500                     emit_gatt_complete_event(gatt_client, ATT_ERROR_DATA_MISMATCH);
1501                     break;
1502                 case P_W4_EXECUTE_PREPARED_WRITE_CHARACTERISTIC_DESCRIPTOR_RESULT:
1503                     gatt_client_handle_transaction_complete(gatt_client);
1504                     emit_gatt_complete_event(gatt_client, ATT_ERROR_SUCCESS);
1505                     break;
1506                 default:
1507                     break;
1508 
1509             }
1510             break;
1511 
1512         case ATT_READ_MULTIPLE_RESPONSE:
1513             switch(gatt_client->gatt_client_state){
1514                 case P_W4_READ_MULTIPLE_RESPONSE:
1515                     report_gatt_characteristic_value(gatt_client, 0u, &packet[1], size - 1u);
1516                     gatt_client_handle_transaction_complete(gatt_client);
1517                     emit_gatt_complete_event(gatt_client, ATT_ERROR_SUCCESS);
1518                     break;
1519                 default:
1520                     break;
1521             }
1522             break;
1523 
1524         case ATT_ERROR_RESPONSE:
1525             if (size < 5u) return;
1526             error_code = packet[4];
1527             switch (error_code){
1528                 case ATT_ERROR_ATTRIBUTE_NOT_FOUND: {
1529                     switch(gatt_client->gatt_client_state){
1530                         case P_W4_SERVICE_QUERY_RESULT:
1531                         case P_W4_SERVICE_WITH_UUID_RESULT:
1532                         case P_W4_INCLUDED_SERVICE_QUERY_RESULT:
1533                         case P_W4_ALL_CHARACTERISTIC_DESCRIPTORS_QUERY_RESULT:
1534                             gatt_client_handle_transaction_complete(gatt_client);
1535                             emit_gatt_complete_event(gatt_client, ATT_ERROR_SUCCESS);
1536                             break;
1537                         case P_W4_ALL_CHARACTERISTICS_OF_SERVICE_QUERY_RESULT:
1538                         case P_W4_CHARACTERISTIC_WITH_UUID_QUERY_RESULT:
1539                             characteristic_end_found(gatt_client, gatt_client->end_group_handle);
1540                             gatt_client_handle_transaction_complete(gatt_client);
1541                             emit_gatt_complete_event(gatt_client, ATT_ERROR_SUCCESS);
1542                             break;
1543                         case P_W4_READ_BY_TYPE_RESPONSE:
1544                             gatt_client_handle_transaction_complete(gatt_client);
1545                             if (gatt_client->start_group_handle == gatt_client->query_start_handle){
1546                                 emit_gatt_complete_event(gatt_client, ATT_ERROR_ATTRIBUTE_NOT_FOUND);
1547                             } else {
1548                                 emit_gatt_complete_event(gatt_client, ATT_ERROR_SUCCESS);
1549                             }
1550                             break;
1551                         default:
1552                             gatt_client_report_error_if_pending(gatt_client, error_code);
1553                             break;
1554                     }
1555                     break;
1556                 }
1557 
1558 #ifdef ENABLE_GATT_CLIENT_PAIRING
1559 
1560                 case ATT_ERROR_INSUFFICIENT_AUTHENTICATION:
1561                 case ATT_ERROR_INSUFFICIENT_ENCRYPTION_KEY_SIZE:
1562                 case ATT_ERROR_INSUFFICIENT_ENCRYPTION: {
1563 
1564                     // security too low
1565                     if (gatt_client->security_counter > 0) {
1566                         gatt_client_report_error_if_pending(gatt_client, error_code);
1567                         break;
1568                     }
1569                     // start security
1570                     gatt_client->security_counter++;
1571 
1572                     // setup action
1573                     int retry = 1;
1574                     switch (gatt_client->gatt_client_state){
1575                         case P_W4_READ_CHARACTERISTIC_VALUE_RESULT:
1576                             gatt_client->gatt_client_state = P_W2_SEND_READ_CHARACTERISTIC_VALUE_QUERY ;
1577                             break;
1578                         case P_W4_READ_BLOB_RESULT:
1579                             gatt_client->gatt_client_state = P_W2_SEND_READ_BLOB_QUERY;
1580                             break;
1581                         case P_W4_READ_BY_TYPE_RESPONSE:
1582                             gatt_client->gatt_client_state = P_W2_SEND_READ_BY_TYPE_REQUEST;
1583                             break;
1584                         case P_W4_READ_MULTIPLE_RESPONSE:
1585                             gatt_client->gatt_client_state = P_W2_SEND_READ_MULTIPLE_REQUEST;
1586                             break;
1587                         case P_W4_WRITE_CHARACTERISTIC_VALUE_RESULT:
1588                             gatt_client->gatt_client_state = P_W2_SEND_WRITE_CHARACTERISTIC_VALUE;
1589                             break;
1590                         case P_W4_PREPARE_WRITE_RESULT:
1591                             gatt_client->gatt_client_state = P_W2_PREPARE_WRITE;
1592                             break;
1593                         case P_W4_PREPARE_WRITE_SINGLE_RESULT:
1594                             gatt_client->gatt_client_state = P_W2_PREPARE_WRITE_SINGLE;
1595                             break;
1596                         case P_W4_PREPARE_RELIABLE_WRITE_RESULT:
1597                             gatt_client->gatt_client_state = P_W2_PREPARE_RELIABLE_WRITE;
1598                             break;
1599                         case P_W4_EXECUTE_PREPARED_WRITE_RESULT:
1600                             gatt_client->gatt_client_state = P_W2_EXECUTE_PREPARED_WRITE;
1601                             break;
1602                         case P_W4_CANCEL_PREPARED_WRITE_RESULT:
1603                             gatt_client->gatt_client_state = P_W2_CANCEL_PREPARED_WRITE;
1604                             break;
1605                         case P_W4_CANCEL_PREPARED_WRITE_DATA_MISMATCH_RESULT:
1606                             gatt_client->gatt_client_state = P_W2_CANCEL_PREPARED_WRITE_DATA_MISMATCH;
1607                             break;
1608                         case P_W4_READ_CHARACTERISTIC_DESCRIPTOR_RESULT:
1609                             gatt_client->gatt_client_state = P_W2_SEND_READ_CHARACTERISTIC_DESCRIPTOR_QUERY;
1610                             break;
1611                         case P_W4_READ_BLOB_CHARACTERISTIC_DESCRIPTOR_RESULT:
1612                             gatt_client->gatt_client_state = P_W2_SEND_READ_BLOB_CHARACTERISTIC_DESCRIPTOR_QUERY;
1613                             break;
1614                         case P_W4_WRITE_CHARACTERISTIC_DESCRIPTOR_RESULT:
1615                             gatt_client->gatt_client_state = P_W2_SEND_WRITE_CHARACTERISTIC_DESCRIPTOR;
1616                             break;
1617                         case P_W4_CLIENT_CHARACTERISTIC_CONFIGURATION_RESULT:
1618                             gatt_client->gatt_client_state = P_W2_WRITE_CLIENT_CHARACTERISTIC_CONFIGURATION;
1619                             break;
1620                         case P_W4_PREPARE_WRITE_CHARACTERISTIC_DESCRIPTOR_RESULT:
1621                             gatt_client->gatt_client_state = P_W2_PREPARE_WRITE_CHARACTERISTIC_DESCRIPTOR;
1622                             break;
1623                         case P_W4_EXECUTE_PREPARED_WRITE_CHARACTERISTIC_DESCRIPTOR_RESULT:
1624                             gatt_client->gatt_client_state = P_W2_EXECUTE_PREPARED_WRITE_CHARACTERISTIC_DESCRIPTOR;
1625                             break;
1626 #ifdef ENABLE_LE_SIGNED_WRITE
1627                         case P_W4_SEND_SINGED_WRITE_DONE:
1628                             gatt_client->gatt_client_state = P_W2_SEND_SIGNED_WRITE;
1629                             break;
1630 #endif
1631                         default:
1632                             log_info("retry not supported for state %x", gatt_client->gatt_client_state);
1633                             retry = 0;
1634                             break;
1635                     }
1636 
1637                     if (!retry) {
1638                         gatt_client_report_error_if_pending(gatt_client, error_code);
1639                         break;
1640                     }
1641 
1642                     log_info("security error, start pairing");
1643 
1644                     // start pairing for higher security level
1645                     gatt_client->wait_for_pairing_complete = 1;
1646                     gatt_client->pending_error_code = error_code;
1647                     sm_request_pairing(gatt_client->con_handle);
1648                     break;
1649                 }
1650 #endif
1651 
1652                 // nothing we can do about that
1653                 case ATT_ERROR_INSUFFICIENT_AUTHORIZATION:
1654                 default:
1655                     gatt_client_report_error_if_pending(gatt_client, error_code);
1656                     break;
1657             }
1658             break;
1659 
1660         default:
1661             log_info("ATT Handler, unhandled response type 0x%02x", packet[0]);
1662             break;
1663     }
1664     gatt_client_run();
1665 }
1666 
1667 #ifdef ENABLE_LE_SIGNED_WRITE
1668 static void att_signed_write_handle_cmac_result(uint8_t hash[8]){
1669     btstack_linked_list_iterator_t it;
1670     btstack_linked_list_iterator_init(&it, &gatt_client_connections);
1671     while (btstack_linked_list_iterator_has_next(&it)){
1672         gatt_client_t * gatt_client = (gatt_client_t *) btstack_linked_list_iterator_next(&it);
1673         if (gatt_client->gatt_client_state == P_W4_CMAC_RESULT){
1674             // store result
1675             (void)memcpy(gatt_client->cmac, hash, 8);
1676             // reverse_64(hash, gatt_client->cmac);
1677             gatt_client->gatt_client_state = P_W2_SEND_SIGNED_WRITE;
1678             gatt_client_run();
1679             return;
1680         }
1681     }
1682 }
1683 
1684 uint8_t gatt_client_signed_write_without_response(btstack_packet_handler_t callback, hci_con_handle_t con_handle, uint16_t handle, uint16_t message_len, uint8_t * message){
1685     gatt_client_t * gatt_client = gatt_client_provide_context_for_handle(con_handle);
1686     if (gatt_client == NULL) return BTSTACK_MEMORY_ALLOC_FAILED;
1687     if (is_ready(gatt_client) == 0) return GATT_CLIENT_IN_WRONG_STATE;
1688 
1689     gatt_client->callback = callback;
1690     gatt_client->attribute_handle = handle;
1691     gatt_client->attribute_length = message_len;
1692     gatt_client->attribute_value = message;
1693     gatt_client->gatt_client_state = P_W4_IDENTITY_RESOLVING;
1694     gatt_client_run();
1695     return ERROR_CODE_SUCCESS;
1696 }
1697 #endif
1698 
1699 uint8_t gatt_client_discover_primary_services(btstack_packet_handler_t callback, hci_con_handle_t con_handle){
1700     gatt_client_t * gatt_client = gatt_client_provide_context_for_handle_and_start_timer(con_handle);
1701     if (gatt_client == NULL) return BTSTACK_MEMORY_ALLOC_FAILED;
1702     if (is_ready(gatt_client) == 0) return GATT_CLIENT_IN_WRONG_STATE;
1703 
1704     gatt_client->callback = callback;
1705     gatt_client->start_group_handle = 0x0001;
1706     gatt_client->end_group_handle   = 0xffff;
1707     gatt_client->gatt_client_state = P_W2_SEND_SERVICE_QUERY;
1708     gatt_client->uuid16 = 0;
1709     gatt_client_run();
1710     return ERROR_CODE_SUCCESS;
1711 }
1712 
1713 
1714 uint8_t gatt_client_discover_primary_services_by_uuid16(btstack_packet_handler_t callback, hci_con_handle_t con_handle, uint16_t uuid16){
1715     gatt_client_t * gatt_client = gatt_client_provide_context_for_handle_and_start_timer(con_handle);
1716     if (gatt_client == NULL) return BTSTACK_MEMORY_ALLOC_FAILED;
1717     if (is_ready(gatt_client) == 0) return GATT_CLIENT_IN_WRONG_STATE;
1718 
1719     gatt_client->callback = callback;
1720     gatt_client->start_group_handle = 0x0001;
1721     gatt_client->end_group_handle   = 0xffff;
1722     gatt_client->gatt_client_state = P_W2_SEND_SERVICE_WITH_UUID_QUERY;
1723     gatt_client->uuid16 = uuid16;
1724     uuid_add_bluetooth_prefix((uint8_t*) &(gatt_client->uuid128), gatt_client->uuid16);
1725     gatt_client_run();
1726     return ERROR_CODE_SUCCESS;
1727 }
1728 
1729 uint8_t gatt_client_discover_primary_services_by_uuid128(btstack_packet_handler_t callback, hci_con_handle_t con_handle, const uint8_t * uuid128){
1730     gatt_client_t * gatt_client = gatt_client_provide_context_for_handle_and_start_timer(con_handle);
1731     if (gatt_client == NULL) return BTSTACK_MEMORY_ALLOC_FAILED;
1732     if (is_ready(gatt_client) == 0) return GATT_CLIENT_IN_WRONG_STATE;
1733 
1734     gatt_client->callback = callback;
1735     gatt_client->start_group_handle = 0x0001;
1736     gatt_client->end_group_handle   = 0xffff;
1737     gatt_client->uuid16 = 0;
1738     (void)memcpy(gatt_client->uuid128, uuid128, 16);
1739     gatt_client->gatt_client_state = P_W2_SEND_SERVICE_WITH_UUID_QUERY;
1740     gatt_client_run();
1741     return ERROR_CODE_SUCCESS;
1742 }
1743 
1744 uint8_t gatt_client_discover_characteristics_for_service(btstack_packet_handler_t callback, hci_con_handle_t con_handle, gatt_client_service_t *service){
1745     gatt_client_t * gatt_client = gatt_client_provide_context_for_handle_and_start_timer(con_handle);
1746     if (gatt_client == NULL) return BTSTACK_MEMORY_ALLOC_FAILED;
1747     if (is_ready(gatt_client) == 0) return GATT_CLIENT_IN_WRONG_STATE;
1748 
1749     gatt_client->callback = callback;
1750     gatt_client->start_group_handle = service->start_group_handle;
1751     gatt_client->end_group_handle   = service->end_group_handle;
1752     gatt_client->filter_with_uuid = 0;
1753     gatt_client->characteristic_start_handle = 0;
1754     gatt_client->gatt_client_state = P_W2_SEND_ALL_CHARACTERISTICS_OF_SERVICE_QUERY;
1755     gatt_client_run();
1756     return ERROR_CODE_SUCCESS;
1757 }
1758 
1759 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){
1760     gatt_client_t * gatt_client = gatt_client_provide_context_for_handle_and_start_timer(con_handle);
1761     if (gatt_client == NULL) return BTSTACK_MEMORY_ALLOC_FAILED;
1762     if (is_ready(gatt_client) == 0) return GATT_CLIENT_IN_WRONG_STATE;
1763     gatt_client->callback = callback;
1764     gatt_client->start_group_handle = service->start_group_handle;
1765     gatt_client->end_group_handle   = service->end_group_handle;
1766     gatt_client->gatt_client_state = P_W2_SEND_INCLUDED_SERVICE_QUERY;
1767 
1768     gatt_client_run();
1769     return ERROR_CODE_SUCCESS;
1770 }
1771 
1772 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){
1773     gatt_client_t * gatt_client = gatt_client_provide_context_for_handle_and_start_timer(con_handle);
1774     if (gatt_client == NULL) return BTSTACK_MEMORY_ALLOC_FAILED;
1775     if (is_ready(gatt_client) == 0) return GATT_CLIENT_IN_WRONG_STATE;
1776 
1777     gatt_client->callback = callback;
1778     gatt_client->start_group_handle = start_handle;
1779     gatt_client->end_group_handle   = end_handle;
1780     gatt_client->filter_with_uuid = 1;
1781     gatt_client->uuid16 = uuid16;
1782     uuid_add_bluetooth_prefix((uint8_t*) &(gatt_client->uuid128), uuid16);
1783     gatt_client->characteristic_start_handle = 0;
1784     gatt_client->gatt_client_state = P_W2_SEND_CHARACTERISTIC_WITH_UUID_QUERY;
1785     gatt_client_run();
1786     return ERROR_CODE_SUCCESS;
1787 }
1788 
1789 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, uint8_t * uuid128){
1790     gatt_client_t * gatt_client = gatt_client_provide_context_for_handle_and_start_timer(con_handle);
1791     if (gatt_client == NULL) return BTSTACK_MEMORY_ALLOC_FAILED;
1792     if (is_ready(gatt_client) == 0) return GATT_CLIENT_IN_WRONG_STATE;
1793 
1794     gatt_client->callback = callback;
1795     gatt_client->start_group_handle = start_handle;
1796     gatt_client->end_group_handle   = end_handle;
1797     gatt_client->filter_with_uuid = 1;
1798     gatt_client->uuid16 = 0;
1799     (void)memcpy(gatt_client->uuid128, uuid128, 16);
1800     gatt_client->characteristic_start_handle = 0;
1801     gatt_client->gatt_client_state = P_W2_SEND_CHARACTERISTIC_WITH_UUID_QUERY;
1802     gatt_client_run();
1803     return ERROR_CODE_SUCCESS;
1804 }
1805 
1806 
1807 uint8_t gatt_client_discover_characteristics_for_service_by_uuid16(btstack_packet_handler_t callback, uint16_t handle, gatt_client_service_t *service, uint16_t  uuid16){
1808     return gatt_client_discover_characteristics_for_handle_range_by_uuid16(callback, handle, service->start_group_handle, service->end_group_handle, uuid16);
1809 }
1810 
1811 uint8_t gatt_client_discover_characteristics_for_service_by_uuid128(btstack_packet_handler_t callback, uint16_t handle, gatt_client_service_t *service, uint8_t * uuid128){
1812     return gatt_client_discover_characteristics_for_handle_range_by_uuid128(callback, handle, service->start_group_handle, service->end_group_handle, uuid128);
1813 }
1814 
1815 uint8_t gatt_client_discover_characteristic_descriptors(btstack_packet_handler_t callback, hci_con_handle_t con_handle, gatt_client_characteristic_t *characteristic){
1816     gatt_client_t * gatt_client = gatt_client_provide_context_for_handle_and_start_timer(con_handle);
1817     if (gatt_client == NULL) return BTSTACK_MEMORY_ALLOC_FAILED;
1818     if (is_ready(gatt_client) == 0) return GATT_CLIENT_IN_WRONG_STATE;
1819 
1820     if (characteristic->value_handle == characteristic->end_handle){
1821         emit_gatt_complete_event(gatt_client, ATT_ERROR_SUCCESS);
1822         return ERROR_CODE_SUCCESS;
1823     }
1824     gatt_client->callback = callback;
1825     gatt_client->start_group_handle = characteristic->value_handle + 1u;
1826     gatt_client->end_group_handle   = characteristic->end_handle;
1827     gatt_client->gatt_client_state = P_W2_SEND_ALL_CHARACTERISTIC_DESCRIPTORS_QUERY;
1828     gatt_client_run();
1829     return ERROR_CODE_SUCCESS;
1830 }
1831 
1832 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){
1833     gatt_client_t * gatt_client = gatt_client_provide_context_for_handle_and_start_timer(con_handle);
1834     if (gatt_client == NULL) return BTSTACK_MEMORY_ALLOC_FAILED;
1835     if (is_ready(gatt_client) == 0) return GATT_CLIENT_IN_WRONG_STATE;
1836 
1837     gatt_client->callback = callback;
1838     gatt_client->attribute_handle = value_handle;
1839     gatt_client->attribute_offset = 0;
1840     gatt_client->gatt_client_state = P_W2_SEND_READ_CHARACTERISTIC_VALUE_QUERY;
1841     gatt_client_run();
1842     return ERROR_CODE_SUCCESS;
1843 }
1844 
1845 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){
1846     gatt_client_t * gatt_client = gatt_client_provide_context_for_handle_and_start_timer(con_handle);
1847     if (gatt_client == NULL) return BTSTACK_MEMORY_ALLOC_FAILED;
1848     if (is_ready(gatt_client) == 0) return GATT_CLIENT_IN_WRONG_STATE;
1849 
1850     gatt_client->callback = callback;
1851     gatt_client->start_group_handle = start_handle;
1852     gatt_client->end_group_handle = end_handle;
1853     gatt_client->query_start_handle = start_handle;
1854     gatt_client->query_end_handle = end_handle;
1855     gatt_client->uuid16 = uuid16;
1856     uuid_add_bluetooth_prefix((uint8_t*) &(gatt_client->uuid128), uuid16);
1857     gatt_client->gatt_client_state = P_W2_SEND_READ_BY_TYPE_REQUEST;
1858     gatt_client_run();
1859     return ERROR_CODE_SUCCESS;
1860 }
1861 
1862 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, uint8_t * uuid128){
1863     gatt_client_t * gatt_client = gatt_client_provide_context_for_handle_and_start_timer(con_handle);
1864     if (gatt_client == NULL) return BTSTACK_MEMORY_ALLOC_FAILED;
1865     if (is_ready(gatt_client) == 0) return GATT_CLIENT_IN_WRONG_STATE;
1866 
1867     gatt_client->callback = callback;
1868     gatt_client->start_group_handle = start_handle;
1869     gatt_client->end_group_handle = end_handle;
1870     gatt_client->query_start_handle = start_handle;
1871     gatt_client->query_end_handle = end_handle;
1872     gatt_client->uuid16 = 0;
1873     (void)memcpy(gatt_client->uuid128, uuid128, 16);
1874     gatt_client->gatt_client_state = P_W2_SEND_READ_BY_TYPE_REQUEST;
1875     gatt_client_run();
1876     return ERROR_CODE_SUCCESS;
1877 }
1878 
1879 
1880 uint8_t gatt_client_read_value_of_characteristic(btstack_packet_handler_t callback, uint16_t handle, gatt_client_characteristic_t *characteristic){
1881     return gatt_client_read_value_of_characteristic_using_value_handle(callback, handle, characteristic->value_handle);
1882 }
1883 
1884 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 characteristic_value_handle, uint16_t offset){
1885     gatt_client_t * gatt_client = gatt_client_provide_context_for_handle_and_start_timer(con_handle);
1886     if (gatt_client == NULL) return BTSTACK_MEMORY_ALLOC_FAILED;
1887     if (is_ready(gatt_client) == 0) return GATT_CLIENT_IN_WRONG_STATE;
1888 
1889     gatt_client->callback = callback;
1890     gatt_client->attribute_handle = characteristic_value_handle;
1891     gatt_client->attribute_offset = offset;
1892     gatt_client->gatt_client_state = P_W2_SEND_READ_BLOB_QUERY;
1893     gatt_client_run();
1894     return ERROR_CODE_SUCCESS;
1895 }
1896 
1897 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 characteristic_value_handle){
1898     return gatt_client_read_long_value_of_characteristic_using_value_handle_with_offset(callback, con_handle, characteristic_value_handle, 0);
1899 }
1900 
1901 uint8_t gatt_client_read_long_value_of_characteristic(btstack_packet_handler_t callback, uint16_t handle, gatt_client_characteristic_t *characteristic){
1902     return gatt_client_read_long_value_of_characteristic_using_value_handle(callback, handle, characteristic->value_handle);
1903 }
1904 
1905 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){
1906     gatt_client_t * gatt_client = gatt_client_provide_context_for_handle_and_start_timer(con_handle);
1907     if (gatt_client == NULL) return BTSTACK_MEMORY_ALLOC_FAILED;
1908     if (is_ready(gatt_client) == 0) return GATT_CLIENT_IN_WRONG_STATE;
1909 
1910     gatt_client->callback = callback;
1911     gatt_client->read_multiple_handle_count = num_value_handles;
1912     gatt_client->read_multiple_handles = value_handles;
1913     gatt_client->gatt_client_state = P_W2_SEND_READ_MULTIPLE_REQUEST;
1914     gatt_client_run();
1915     return ERROR_CODE_SUCCESS;
1916 }
1917 
1918 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){
1919     gatt_client_t * gatt_client = gatt_client_provide_context_for_handle(con_handle);
1920     if (gatt_client == NULL) return BTSTACK_MEMORY_ALLOC_FAILED;
1921 
1922     if (value_length > (gatt_client->mtu - 3u)) return GATT_CLIENT_VALUE_TOO_LONG;
1923     if (!att_dispatch_client_can_send_now(gatt_client->con_handle)) return GATT_CLIENT_BUSY;
1924 
1925     return att_write_request(ATT_WRITE_COMMAND, gatt_client->con_handle, value_handle, value_length, value);
1926 }
1927 
1928 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 * data){
1929     gatt_client_t * gatt_client = gatt_client_provide_context_for_handle_and_start_timer(con_handle);
1930     if (gatt_client == NULL) return BTSTACK_MEMORY_ALLOC_FAILED;
1931     if (is_ready(gatt_client) == 0) return GATT_CLIENT_IN_WRONG_STATE;
1932 
1933     gatt_client->callback = callback;
1934     gatt_client->attribute_handle = value_handle;
1935     gatt_client->attribute_length = value_length;
1936     gatt_client->attribute_value = data;
1937     gatt_client->gatt_client_state = P_W2_SEND_WRITE_CHARACTERISTIC_VALUE;
1938     gatt_client_run();
1939     return ERROR_CODE_SUCCESS;
1940 }
1941 
1942 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  * data){
1943     gatt_client_t * gatt_client = gatt_client_provide_context_for_handle_and_start_timer(con_handle);
1944     if (gatt_client == NULL) return BTSTACK_MEMORY_ALLOC_FAILED;
1945     if (is_ready(gatt_client) == 0) return GATT_CLIENT_IN_WRONG_STATE;
1946 
1947     gatt_client->callback = callback;
1948     gatt_client->attribute_handle = value_handle;
1949     gatt_client->attribute_length = value_length;
1950     gatt_client->attribute_offset = offset;
1951     gatt_client->attribute_value = data;
1952     gatt_client->gatt_client_state = P_W2_PREPARE_WRITE;
1953     gatt_client_run();
1954     return ERROR_CODE_SUCCESS;
1955 }
1956 
1957 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){
1958     return gatt_client_write_long_value_of_characteristic_with_offset(callback, con_handle, value_handle, 0, value_length, value);
1959 }
1960 
1961 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){
1962     gatt_client_t * gatt_client = gatt_client_provide_context_for_handle_and_start_timer(con_handle);
1963     if (gatt_client == NULL) return BTSTACK_MEMORY_ALLOC_FAILED;
1964     if (is_ready(gatt_client) == 0) return GATT_CLIENT_IN_WRONG_STATE;
1965 
1966     gatt_client->callback = callback;
1967     gatt_client->attribute_handle = value_handle;
1968     gatt_client->attribute_length = value_length;
1969     gatt_client->attribute_offset = 0;
1970     gatt_client->attribute_value = value;
1971     gatt_client->gatt_client_state = P_W2_PREPARE_RELIABLE_WRITE;
1972     gatt_client_run();
1973     return ERROR_CODE_SUCCESS;
1974 }
1975 
1976 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){
1977     gatt_client_t * gatt_client = gatt_client_provide_context_for_handle_and_start_timer(con_handle);
1978     if (gatt_client == NULL) return BTSTACK_MEMORY_ALLOC_FAILED;
1979     if (is_ready(gatt_client) == 0) return GATT_CLIENT_IN_WRONG_STATE;
1980 
1981     if ( (configuration & GATT_CLIENT_CHARACTERISTICS_CONFIGURATION_NOTIFICATION) &&
1982         ((characteristic->properties & ATT_PROPERTY_NOTIFY) == 0u)) {
1983         log_info("gatt_client_write_client_characteristic_configuration: GATT_CLIENT_CHARACTERISTIC_NOTIFICATION_NOT_SUPPORTED");
1984         return GATT_CLIENT_CHARACTERISTIC_NOTIFICATION_NOT_SUPPORTED;
1985     } else if ( (configuration & GATT_CLIENT_CHARACTERISTICS_CONFIGURATION_INDICATION) &&
1986                ((characteristic->properties & ATT_PROPERTY_INDICATE) == 0u)){
1987         log_info("gatt_client_write_client_characteristic_configuration: GATT_CLIENT_CHARACTERISTIC_INDICATION_NOT_SUPPORTED");
1988         return GATT_CLIENT_CHARACTERISTIC_INDICATION_NOT_SUPPORTED;
1989     }
1990 
1991     gatt_client->callback = callback;
1992     gatt_client->start_group_handle = characteristic->value_handle;
1993     gatt_client->end_group_handle = characteristic->end_handle;
1994     little_endian_store_16(gatt_client->client_characteristic_configuration_value, 0, configuration);
1995 
1996 #ifdef ENABLE_GATT_FIND_INFORMATION_FOR_CCC_DISCOVERY
1997     gatt_client->gatt_client_state = P_W2_SEND_FIND_CLIENT_CHARACTERISTIC_CONFIGURATION_QUERY;
1998 #else
1999     gatt_client->gatt_client_state = P_W2_SEND_READ_CLIENT_CHARACTERISTIC_CONFIGURATION_QUERY;
2000 #endif
2001     gatt_client_run();
2002     return ERROR_CODE_SUCCESS;
2003 }
2004 
2005 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){
2006     gatt_client_t * gatt_client = gatt_client_provide_context_for_handle_and_start_timer(con_handle);
2007     if (gatt_client == NULL) return BTSTACK_MEMORY_ALLOC_FAILED;
2008     if (is_ready(gatt_client) == 0) return GATT_CLIENT_IN_WRONG_STATE;
2009 
2010     gatt_client->callback = callback;
2011     gatt_client->attribute_handle = descriptor_handle;
2012 
2013     gatt_client->gatt_client_state = P_W2_SEND_READ_CHARACTERISTIC_DESCRIPTOR_QUERY;
2014     gatt_client_run();
2015     return ERROR_CODE_SUCCESS;
2016 }
2017 
2018 uint8_t gatt_client_read_characteristic_descriptor(btstack_packet_handler_t callback, hci_con_handle_t con_handle, gatt_client_characteristic_descriptor_t * descriptor){
2019     return gatt_client_read_characteristic_descriptor_using_descriptor_handle(callback, con_handle, descriptor->handle);
2020 }
2021 
2022 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){
2023     gatt_client_t * gatt_client = gatt_client_provide_context_for_handle_and_start_timer(con_handle);
2024     if (gatt_client == NULL) return BTSTACK_MEMORY_ALLOC_FAILED;
2025     if (is_ready(gatt_client) == 0) return GATT_CLIENT_IN_WRONG_STATE;
2026 
2027     gatt_client->callback = callback;
2028     gatt_client->attribute_handle = descriptor_handle;
2029     gatt_client->attribute_offset = offset;
2030     gatt_client->gatt_client_state = P_W2_SEND_READ_BLOB_CHARACTERISTIC_DESCRIPTOR_QUERY;
2031     gatt_client_run();
2032     return ERROR_CODE_SUCCESS;
2033 }
2034 
2035 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){
2036     return gatt_client_read_long_characteristic_descriptor_using_descriptor_handle_with_offset(callback, con_handle, descriptor_handle, 0);
2037 }
2038 
2039 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){
2040     return gatt_client_read_long_characteristic_descriptor_using_descriptor_handle(callback, con_handle, descriptor->handle);
2041 }
2042 
2043 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 length, uint8_t  * data){
2044     gatt_client_t * gatt_client = gatt_client_provide_context_for_handle_and_start_timer(con_handle);
2045     if (gatt_client == NULL) return BTSTACK_MEMORY_ALLOC_FAILED;
2046     if (is_ready(gatt_client) == 0) return GATT_CLIENT_IN_WRONG_STATE;
2047 
2048     gatt_client->callback = callback;
2049     gatt_client->attribute_handle = descriptor_handle;
2050     gatt_client->attribute_length = length;
2051     gatt_client->attribute_offset = 0;
2052     gatt_client->attribute_value = data;
2053     gatt_client->gatt_client_state = P_W2_SEND_WRITE_CHARACTERISTIC_DESCRIPTOR;
2054     gatt_client_run();
2055     return ERROR_CODE_SUCCESS;
2056 }
2057 
2058 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 length, uint8_t * value){
2059     return gatt_client_write_characteristic_descriptor_using_descriptor_handle(callback, con_handle, descriptor->handle, length, value);
2060 }
2061 
2062 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 length, uint8_t  * data){
2063     gatt_client_t * gatt_client = gatt_client_provide_context_for_handle_and_start_timer(con_handle);
2064     if (gatt_client == NULL) return BTSTACK_MEMORY_ALLOC_FAILED;
2065     if (is_ready(gatt_client) == 0) return GATT_CLIENT_IN_WRONG_STATE;
2066 
2067     gatt_client->callback = callback;
2068     gatt_client->attribute_handle = descriptor_handle;
2069     gatt_client->attribute_length = length;
2070     gatt_client->attribute_offset = offset;
2071     gatt_client->attribute_value = data;
2072     gatt_client->gatt_client_state = P_W2_PREPARE_WRITE_CHARACTERISTIC_DESCRIPTOR;
2073     gatt_client_run();
2074     return ERROR_CODE_SUCCESS;
2075 }
2076 
2077 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 length, uint8_t * data){
2078     return gatt_client_write_long_characteristic_descriptor_using_descriptor_handle_with_offset(callback, con_handle, descriptor_handle, 0, length, data );
2079 }
2080 
2081 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 length, uint8_t * value){
2082     return gatt_client_write_long_characteristic_descriptor_using_descriptor_handle(callback, con_handle, descriptor->handle, length, value);
2083 }
2084 
2085 /**
2086  * @brief -> gatt complete event
2087  */
2088 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 length, uint8_t * data){
2089     gatt_client_t * gatt_client = gatt_client_provide_context_for_handle_and_start_timer(con_handle);
2090     if (gatt_client == NULL) return BTSTACK_MEMORY_ALLOC_FAILED;
2091     if (is_ready(gatt_client) == 0) return GATT_CLIENT_IN_WRONG_STATE;
2092 
2093     gatt_client->callback = callback;
2094     gatt_client->attribute_handle = attribute_handle;
2095     gatt_client->attribute_length = length;
2096     gatt_client->attribute_offset = offset;
2097     gatt_client->attribute_value = data;
2098     gatt_client->gatt_client_state = P_W2_PREPARE_WRITE_SINGLE;
2099     gatt_client_run();
2100     return ERROR_CODE_SUCCESS;
2101 }
2102 
2103 /**
2104  * @brief -> gatt complete event
2105  */
2106 uint8_t gatt_client_execute_write(btstack_packet_handler_t callback, hci_con_handle_t con_handle){
2107     gatt_client_t * gatt_client = gatt_client_provide_context_for_handle_and_start_timer(con_handle);
2108 
2109     if (gatt_client == NULL) return BTSTACK_MEMORY_ALLOC_FAILED;
2110     if (is_ready(gatt_client) == 0) return GATT_CLIENT_IN_WRONG_STATE;
2111 
2112     gatt_client->callback = callback;
2113     gatt_client->gatt_client_state = P_W2_EXECUTE_PREPARED_WRITE;
2114     gatt_client_run();
2115     return ERROR_CODE_SUCCESS;
2116 }
2117 
2118 /**
2119  * @brief -> gatt complete event
2120  */
2121 uint8_t gatt_client_cancel_write(btstack_packet_handler_t callback, hci_con_handle_t con_handle){
2122     gatt_client_t * gatt_client = gatt_client_provide_context_for_handle_and_start_timer(con_handle);
2123     if (gatt_client == NULL) return BTSTACK_MEMORY_ALLOC_FAILED;
2124     if (is_ready(gatt_client) == 0) return GATT_CLIENT_IN_WRONG_STATE;
2125 
2126     gatt_client->callback = callback;
2127     gatt_client->gatt_client_state = P_W2_CANCEL_PREPARED_WRITE;
2128     gatt_client_run();
2129     return ERROR_CODE_SUCCESS;
2130 }
2131 
2132 void gatt_client_deserialize_service(const uint8_t *packet, int offset, gatt_client_service_t *service){
2133     service->start_group_handle = little_endian_read_16(packet, offset);
2134     service->end_group_handle = little_endian_read_16(packet, offset + 2);
2135     reverse_128(&packet[offset + 4], service->uuid128);
2136     if (uuid_has_bluetooth_prefix(service->uuid128)){
2137         service->uuid16 = big_endian_read_32(service->uuid128, 0);
2138     } else {
2139         service->uuid16 = 0;
2140     }
2141 }
2142 
2143 void gatt_client_deserialize_characteristic(const uint8_t * packet, int offset, gatt_client_characteristic_t * characteristic){
2144     characteristic->start_handle = little_endian_read_16(packet, offset);
2145     characteristic->value_handle = little_endian_read_16(packet, offset + 2);
2146     characteristic->end_handle = little_endian_read_16(packet, offset + 4);
2147     characteristic->properties = little_endian_read_16(packet, offset + 6);
2148     reverse_128(&packet[offset+8], characteristic->uuid128);
2149     if (uuid_has_bluetooth_prefix(characteristic->uuid128)){
2150         characteristic->uuid16 = big_endian_read_32(characteristic->uuid128, 0);
2151     } else {
2152         characteristic->uuid16 = 0;
2153     }
2154 }
2155 
2156 void gatt_client_deserialize_characteristic_descriptor(const uint8_t * packet, int offset, gatt_client_characteristic_descriptor_t * descriptor){
2157     descriptor->handle = little_endian_read_16(packet, offset);
2158     reverse_128(&packet[offset+2], descriptor->uuid128);
2159     if (uuid_has_bluetooth_prefix(descriptor->uuid128)){
2160         descriptor->uuid16 = big_endian_read_32(descriptor->uuid128, 0);
2161     } else {
2162         descriptor->uuid16 = 0;
2163     }
2164 }
2165 
2166 void gatt_client_send_mtu_negotiation(btstack_packet_handler_t callback, hci_con_handle_t con_handle){
2167     gatt_client_t * context = gatt_client_provide_context_for_handle(con_handle);
2168     if (context == NULL) return;
2169     if (context->mtu_state == MTU_AUTO_EXCHANGE_DISABLED){
2170         context->callback = callback;
2171         context->mtu_state = SEND_MTU_EXCHANGE;
2172         gatt_client_run();
2173     }
2174 }
2175 
2176 uint8_t gatt_client_request_can_write_without_response_event(btstack_packet_handler_t callback, hci_con_handle_t con_handle){
2177     gatt_client_t * context = gatt_client_provide_context_for_handle(con_handle);
2178     if (context == NULL) return BTSTACK_MEMORY_ALLOC_FAILED;
2179     if (context->write_without_response_callback != NULL) return GATT_CLIENT_IN_WRONG_STATE;
2180     context->write_without_response_callback = callback;
2181     att_dispatch_client_request_can_send_now_event(context->con_handle);
2182     return ERROR_CODE_SUCCESS;
2183 }
2184 
2185 #ifdef FUZZING_BUILD_MODE_UNSAFE_FOR_PRODUCTION
2186 void gatt_client_att_packet_handler_fuzz(uint8_t packet_type, uint16_t handle, uint8_t *packet, uint16_t size){
2187     gatt_client_att_packet_handler(packet_type, handle, packet, size);
2188 }
2189 #endif
2190