xref: /btstack/src/ble/gatt_client.c (revision 6c124bc24f267d5ae707c5d5137367237eff4d16)
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_LE_PROACTIVE_AUTHENTICATION
867     // wait until re-encryption complete
868     if (gatt_client->reencryption_active) return 0;
869 
870     // report bonding information missing, if re-encryption failed
871     if ((gatt_client->reencryption_result != ERROR_CODE_SUCCESS) && (gatt_client->gatt_client_state != P_READY)){
872         gatt_client_handle_transaction_complete(gatt_client);
873         emit_gatt_complete_event(gatt_client, ATT_ERROR_BONDING_INFORMATION_MISSING);
874         return 0;
875     }
876 #endif
877 
878 #ifdef ENABLE_GATT_CLIENT_PAIRING
879     // wait until pairing complete
880     if (gatt_client->wait_for_pairing_complete) return 0;
881 #endif
882 
883     switch (gatt_client->mtu_state) {
884         case SEND_MTU_EXCHANGE:
885             gatt_client->mtu_state = SENT_MTU_EXCHANGE;
886             att_exchange_mtu_request(gatt_client->con_handle);
887             return 1;
888         case SENT_MTU_EXCHANGE:
889             return 0;
890         default:
891             break;
892     }
893 
894     if (gatt_client->send_confirmation){
895         gatt_client->send_confirmation = 0;
896         att_confirmation(gatt_client->con_handle);
897         return 1;
898     }
899 
900     // check MTU for writes
901     switch (gatt_client->gatt_client_state){
902         case P_W2_SEND_WRITE_CHARACTERISTIC_VALUE:
903         case P_W2_SEND_WRITE_CHARACTERISTIC_DESCRIPTOR:
904             if (gatt_client->attribute_length <= (gatt_client->mtu - 3u)) break;
905             log_error("gatt_client_run: value len %u > MTU %u - 3\n", gatt_client->attribute_length,gatt_client->mtu);
906             gatt_client_handle_transaction_complete(gatt_client);
907             emit_gatt_complete_event(gatt_client, ATT_ERROR_INVALID_ATTRIBUTE_VALUE_LENGTH);
908             return 0;
909         default:
910             break;
911     }
912 
913     switch (gatt_client->gatt_client_state){
914         case P_W2_SEND_SERVICE_QUERY:
915             gatt_client->gatt_client_state = P_W4_SERVICE_QUERY_RESULT;
916             send_gatt_services_request(gatt_client);
917             return 1;
918 
919         case P_W2_SEND_SERVICE_WITH_UUID_QUERY:
920             gatt_client->gatt_client_state = P_W4_SERVICE_WITH_UUID_RESULT;
921             send_gatt_services_by_uuid_request(gatt_client);
922             return 1;
923 
924         case P_W2_SEND_ALL_CHARACTERISTICS_OF_SERVICE_QUERY:
925             gatt_client->gatt_client_state = P_W4_ALL_CHARACTERISTICS_OF_SERVICE_QUERY_RESULT;
926             send_gatt_characteristic_request(gatt_client);
927             return 1;
928 
929         case P_W2_SEND_CHARACTERISTIC_WITH_UUID_QUERY:
930             gatt_client->gatt_client_state = P_W4_CHARACTERISTIC_WITH_UUID_QUERY_RESULT;
931             send_gatt_characteristic_request(gatt_client);
932             return 1;
933 
934         case P_W2_SEND_ALL_CHARACTERISTIC_DESCRIPTORS_QUERY:
935             gatt_client->gatt_client_state = P_W4_CHARACTERISTIC_WITH_UUID_QUERY_RESULT;
936             send_gatt_characteristic_descriptor_request(gatt_client);
937             return 1;
938 
939         case P_W2_SEND_INCLUDED_SERVICE_QUERY:
940             gatt_client->gatt_client_state = P_W4_INCLUDED_SERVICE_QUERY_RESULT;
941             send_gatt_included_service_request(gatt_client);
942             return 1;
943 
944         case P_W2_SEND_INCLUDED_SERVICE_WITH_UUID_QUERY:
945             gatt_client->gatt_client_state = P_W4_INCLUDED_SERVICE_UUID_WITH_QUERY_RESULT;
946             send_gatt_included_service_uuid_request(gatt_client);
947             return 1;
948 
949         case P_W2_SEND_READ_CHARACTERISTIC_VALUE_QUERY:
950             gatt_client->gatt_client_state = P_W4_READ_CHARACTERISTIC_VALUE_RESULT;
951             send_gatt_read_characteristic_value_request(gatt_client);
952             return 1;
953 
954         case P_W2_SEND_READ_BLOB_QUERY:
955             gatt_client->gatt_client_state = P_W4_READ_BLOB_RESULT;
956             send_gatt_read_blob_request(gatt_client);
957             return 1;
958 
959         case P_W2_SEND_READ_BY_TYPE_REQUEST:
960             gatt_client->gatt_client_state = P_W4_READ_BY_TYPE_RESPONSE;
961             send_gatt_read_by_type_request(gatt_client);
962             return 1;
963 
964         case P_W2_SEND_READ_MULTIPLE_REQUEST:
965             gatt_client->gatt_client_state = P_W4_READ_MULTIPLE_RESPONSE;
966             send_gatt_read_multiple_request(gatt_client);
967             return 1;
968 
969         case P_W2_SEND_WRITE_CHARACTERISTIC_VALUE:
970             gatt_client->gatt_client_state = P_W4_WRITE_CHARACTERISTIC_VALUE_RESULT;
971             send_gatt_write_attribute_value_request(gatt_client);
972             return 1;
973 
974         case P_W2_PREPARE_WRITE:
975             gatt_client->gatt_client_state = P_W4_PREPARE_WRITE_RESULT;
976             send_gatt_prepare_write_request(gatt_client);
977             return 1;
978 
979         case P_W2_PREPARE_WRITE_SINGLE:
980             gatt_client->gatt_client_state = P_W4_PREPARE_WRITE_SINGLE_RESULT;
981             send_gatt_prepare_write_request(gatt_client);
982             return 1;
983 
984         case P_W2_PREPARE_RELIABLE_WRITE:
985             gatt_client->gatt_client_state = P_W4_PREPARE_RELIABLE_WRITE_RESULT;
986             send_gatt_prepare_write_request(gatt_client);
987             return 1;
988 
989         case P_W2_EXECUTE_PREPARED_WRITE:
990             gatt_client->gatt_client_state = P_W4_EXECUTE_PREPARED_WRITE_RESULT;
991             send_gatt_execute_write_request(gatt_client);
992             return 1;
993 
994         case P_W2_CANCEL_PREPARED_WRITE:
995             gatt_client->gatt_client_state = P_W4_CANCEL_PREPARED_WRITE_RESULT;
996             send_gatt_cancel_prepared_write_request(gatt_client);
997             return 1;
998 
999         case P_W2_CANCEL_PREPARED_WRITE_DATA_MISMATCH:
1000             gatt_client->gatt_client_state = P_W4_CANCEL_PREPARED_WRITE_DATA_MISMATCH_RESULT;
1001             send_gatt_cancel_prepared_write_request(gatt_client);
1002             return 1;
1003 
1004 #ifdef ENABLE_GATT_FIND_INFORMATION_FOR_CCC_DISCOVERY
1005         case P_W2_SEND_FIND_CLIENT_CHARACTERISTIC_CONFIGURATION_QUERY:
1006             // use Find Information
1007             gatt_client->gatt_client_state = P_W4_FIND_CLIENT_CHARACTERISTIC_CONFIGURATION_QUERY_RESULT;
1008             send_gatt_characteristic_descriptor_request(gatt_client);
1009 #else
1010         case P_W2_SEND_READ_CLIENT_CHARACTERISTIC_CONFIGURATION_QUERY:
1011             // Use Read By Type
1012             gatt_client->gatt_client_state = P_W4_READ_CLIENT_CHARACTERISTIC_CONFIGURATION_QUERY_RESULT;
1013             send_gatt_read_client_characteristic_configuration_request(gatt_client);
1014 #endif
1015             return 1;
1016 
1017         case P_W2_SEND_READ_CHARACTERISTIC_DESCRIPTOR_QUERY:
1018             gatt_client->gatt_client_state = P_W4_READ_CHARACTERISTIC_DESCRIPTOR_RESULT;
1019             send_gatt_read_characteristic_descriptor_request(gatt_client);
1020             return 1;
1021 
1022         case P_W2_SEND_READ_BLOB_CHARACTERISTIC_DESCRIPTOR_QUERY:
1023             gatt_client->gatt_client_state = P_W4_READ_BLOB_CHARACTERISTIC_DESCRIPTOR_RESULT;
1024             send_gatt_read_blob_request(gatt_client);
1025             return 1;
1026 
1027         case P_W2_SEND_WRITE_CHARACTERISTIC_DESCRIPTOR:
1028             gatt_client->gatt_client_state = P_W4_WRITE_CHARACTERISTIC_DESCRIPTOR_RESULT;
1029             send_gatt_write_attribute_value_request(gatt_client);
1030             return 1;
1031 
1032         case P_W2_WRITE_CLIENT_CHARACTERISTIC_CONFIGURATION:
1033             gatt_client->gatt_client_state = P_W4_CLIENT_CHARACTERISTIC_CONFIGURATION_RESULT;
1034             send_gatt_write_client_characteristic_configuration_request(gatt_client);
1035             return 1;
1036 
1037         case P_W2_PREPARE_WRITE_CHARACTERISTIC_DESCRIPTOR:
1038             gatt_client->gatt_client_state = P_W4_PREPARE_WRITE_CHARACTERISTIC_DESCRIPTOR_RESULT;
1039             send_gatt_prepare_write_request(gatt_client);
1040             return 1;
1041 
1042         case P_W2_EXECUTE_PREPARED_WRITE_CHARACTERISTIC_DESCRIPTOR:
1043             gatt_client->gatt_client_state = P_W4_EXECUTE_PREPARED_WRITE_CHARACTERISTIC_DESCRIPTOR_RESULT;
1044             send_gatt_execute_write_request(gatt_client);
1045             return 1;
1046 
1047 #ifdef ENABLE_LE_SIGNED_WRITE
1048         case P_W4_IDENTITY_RESOLVING:
1049             log_info("P_W4_IDENTITY_RESOLVING - state %x", sm_identity_resolving_state(gatt_client->con_handle));
1050             switch (sm_identity_resolving_state(gatt_client->con_handle)){
1051                 case IRK_LOOKUP_SUCCEEDED:
1052                     gatt_client->le_device_index = sm_le_device_index(gatt_client->con_handle);
1053                     gatt_client->gatt_client_state = P_W4_CMAC_READY;
1054                     break;
1055                 case IRK_LOOKUP_FAILED:
1056                     gatt_client_handle_transaction_complete(gatt_client);
1057                     emit_gatt_complete_event(gatt_client, ATT_ERROR_BONDING_INFORMATION_MISSING);
1058                     return 0;
1059                 default:
1060                     return 0;
1061             }
1062 
1063             /* Fall through */
1064 
1065         case P_W4_CMAC_READY:
1066             if (sm_cmac_ready()){
1067                 sm_key_t csrk;
1068                 le_device_db_local_csrk_get(gatt_client->le_device_index, csrk);
1069                 uint32_t sign_counter = le_device_db_local_counter_get(gatt_client->le_device_index);
1070                 gatt_client->gatt_client_state = P_W4_CMAC_RESULT;
1071                 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);
1072             }
1073             return 0;
1074 
1075         case P_W2_SEND_SIGNED_WRITE: {
1076             gatt_client->gatt_client_state = P_W4_SEND_SINGED_WRITE_DONE;
1077             // bump local signing counter
1078             uint32_t sign_counter = le_device_db_local_counter_get(gatt_client->le_device_index);
1079             le_device_db_local_counter_set(gatt_client->le_device_index, sign_counter + 1);
1080             // send signed write command
1081             send_gatt_signed_write_request(gatt_client, sign_counter);
1082             // finally, notifiy client that write is complete
1083             gatt_client_handle_transaction_complete(gatt_client);
1084             emit_gatt_complete_event(gatt_client, ATT_ERROR_SUCCESS);
1085             return 1;
1086         }
1087 #endif
1088         default:
1089             break;
1090     }
1091 
1092     // requested can send snow?
1093     if (gatt_client->write_without_response_callback){
1094         btstack_packet_handler_t packet_handler = gatt_client->write_without_response_callback;
1095         gatt_client->write_without_response_callback = NULL;
1096         uint8_t event[4];
1097         event[0] = GATT_EVENT_CAN_WRITE_WITHOUT_RESPONSE;
1098         event[1] = sizeof(event) - 2u;
1099         little_endian_store_16(event, 2, gatt_client->con_handle);
1100         packet_handler(HCI_EVENT_PACKET, gatt_client->con_handle, event, sizeof(event));
1101         return 1; // to trigger requeueing (even if higher layer didn't sent)
1102     }
1103 
1104     return 0;
1105 }
1106 
1107 static void gatt_client_run(void){
1108     btstack_linked_item_t *it;
1109     for (it = (btstack_linked_item_t *) gatt_client_connections; it != NULL; it = it->next){
1110         gatt_client_t * gatt_client = (gatt_client_t *) it;
1111         if (!att_dispatch_client_can_send_now(gatt_client->con_handle)) {
1112             att_dispatch_client_request_can_send_now_event(gatt_client->con_handle);
1113             return;
1114         }
1115         int packet_sent = gatt_client_run_for_gatt_client(gatt_client);
1116         if (packet_sent){
1117             // request new permission
1118             att_dispatch_client_request_can_send_now_event(gatt_client->con_handle);
1119             // requeue client for fairness and exit
1120             // note: iterator has become invalid
1121             btstack_linked_list_remove(&gatt_client_connections, (btstack_linked_item_t *) gatt_client);
1122             btstack_linked_list_add_tail(&gatt_client_connections, (btstack_linked_item_t *) gatt_client);
1123             return;
1124         }
1125     }
1126 }
1127 
1128 static void gatt_client_report_error_if_pending(gatt_client_t *gatt_client, uint8_t att_error_code) {
1129     if (is_ready(gatt_client) == 1) return;
1130     gatt_client_handle_transaction_complete(gatt_client);
1131     emit_gatt_complete_event(gatt_client, att_error_code);
1132 }
1133 
1134 static void gatt_client_event_packet_handler(uint8_t packet_type, uint16_t channel, uint8_t *packet, uint16_t size){
1135     UNUSED(channel);    // ok: handling own l2cap events
1136     UNUSED(size);       // ok: there is no channel
1137 
1138     if (packet_type != HCI_EVENT_PACKET) return;
1139 
1140     hci_con_handle_t con_handle;
1141     gatt_client_t * gatt_client;
1142     switch (hci_event_packet_get_type(packet)) {
1143         case HCI_EVENT_DISCONNECTION_COMPLETE:
1144             log_info("GATT Client: HCI_EVENT_DISCONNECTION_COMPLETE");
1145             con_handle = little_endian_read_16(packet,3);
1146             gatt_client = gatt_client_get_context_for_handle(con_handle);
1147             if (gatt_client == NULL) break;
1148 
1149             gatt_client_report_error_if_pending(gatt_client, ATT_ERROR_HCI_DISCONNECT_RECEIVED);
1150             gatt_client_timeout_stop(gatt_client);
1151             btstack_linked_list_remove(&gatt_client_connections, (btstack_linked_item_t *) gatt_client);
1152             btstack_memory_gatt_client_free(gatt_client);
1153             break;
1154 
1155 #ifdef ENABLE_GATT_CLIENT_PAIRING
1156         // Pairing complete (with/without bonding=storing of pairing information)
1157         case SM_EVENT_PAIRING_COMPLETE:
1158             con_handle = sm_event_pairing_complete_get_handle(packet);
1159             gatt_client = gatt_client_get_context_for_handle(con_handle);
1160             if (gatt_client == NULL) break;
1161 
1162             if (gatt_client->wait_for_pairing_complete){
1163                 gatt_client->wait_for_pairing_complete = 0;
1164                 if (sm_event_pairing_complete_get_status(packet)){
1165                     log_info("pairing failed, report previous error 0x%x", gatt_client->pending_error_code);
1166                     gatt_client_report_error_if_pending(gatt_client, gatt_client->pending_error_code);
1167                 } else {
1168                     log_info("pairing success, retry operation");
1169                 }
1170             }
1171             break;
1172 #endif
1173 #ifdef ENABLE_LE_SIGNED_WRITE
1174         // Identity Resolving completed (no code, gatt_client_run will continue)
1175         case SM_EVENT_IDENTITY_RESOLVING_SUCCEEDED:
1176         case SM_EVENT_IDENTITY_RESOLVING_FAILED:
1177             break;
1178 #endif
1179 #ifdef ENABLE_LE_PROACTIVE_AUTHENTICATION
1180         // re-encryption started
1181         case SM_EVENT_REENCRYPTION_STARTED:
1182             con_handle = sm_event_reencryption_complete_get_handle(packet);
1183             gatt_client = gatt_client_get_context_for_handle(con_handle);
1184             if (gatt_client == NULL) break;
1185 
1186             gatt_client->reencryption_active = true;
1187             gatt_client->reencryption_result = ERROR_CODE_SUCCESS;
1188             break;
1189 
1190         // re-encryption complete
1191         case SM_EVENT_REENCRYPTION_COMPLETE:
1192             con_handle = sm_event_reencryption_complete_get_handle(packet);
1193             gatt_client = gatt_client_get_context_for_handle(con_handle);
1194             if (gatt_client == NULL) break;
1195 
1196             gatt_client->reencryption_result = sm_event_reencryption_complete_get_status(packet);
1197             gatt_client->reencryption_active = false;
1198             break;
1199 #endif
1200         default:
1201             break;
1202     }
1203 
1204     gatt_client_run();
1205 }
1206 
1207 static void gatt_client_att_packet_handler(uint8_t packet_type, uint16_t handle, uint8_t *packet, uint16_t size){
1208     gatt_client_t * gatt_client;
1209     if (size < 1u) return;
1210 
1211     if (packet_type == HCI_EVENT_PACKET) {
1212         switch (packet[0]){
1213             case L2CAP_EVENT_CAN_SEND_NOW:
1214                 gatt_client_run();
1215                 break;
1216             // att_server has negotiated the mtu for this connection, cache if context exists
1217             case ATT_EVENT_MTU_EXCHANGE_COMPLETE:
1218                 if (size < 6u) break;
1219                 gatt_client = gatt_client_get_context_for_handle(handle);
1220                 if (gatt_client == NULL) break;
1221                 gatt_client->mtu = little_endian_read_16(packet, 4);
1222                 break;
1223             default:
1224                 break;
1225         }
1226         return;
1227     }
1228 
1229     if (packet_type != ATT_DATA_PACKET) return;
1230 
1231     // special cases: notifications don't need a context while indications motivate creating one
1232     switch (packet[0]){
1233         case ATT_HANDLE_VALUE_NOTIFICATION:
1234             if (size < 3u) return;
1235             report_gatt_notification(handle, little_endian_read_16(packet,1u), &packet[3], size-3u);
1236             return;
1237         case ATT_HANDLE_VALUE_INDICATION:
1238             gatt_client = gatt_client_provide_context_for_handle(handle);
1239             break;
1240         default:
1241             gatt_client = gatt_client_get_context_for_handle(handle);
1242             break;
1243     }
1244 
1245     if (gatt_client == NULL) return;
1246 
1247     uint8_t error_code;
1248     switch (packet[0]){
1249         case ATT_EXCHANGE_MTU_RESPONSE:
1250         {
1251             if (size < 3u) break;
1252             uint16_t remote_rx_mtu = little_endian_read_16(packet, 1);
1253             uint16_t local_rx_mtu = l2cap_max_le_mtu();
1254             gatt_client->mtu = (remote_rx_mtu < local_rx_mtu) ? remote_rx_mtu : local_rx_mtu;
1255             gatt_client->mtu_state = MTU_EXCHANGED;
1256             emit_gatt_mtu_exchanged_result_event(gatt_client, gatt_client->mtu);
1257             break;
1258         }
1259         case ATT_READ_BY_GROUP_TYPE_RESPONSE:
1260             switch(gatt_client->gatt_client_state){
1261                 case P_W4_SERVICE_QUERY_RESULT:
1262                     report_gatt_services(gatt_client, packet, size);
1263                     trigger_next_service_query(gatt_client, get_last_result_handle_from_service_list(packet, size));
1264                     // GATT_EVENT_QUERY_COMPLETE is emitted by trigger_next_xxx when done
1265                     break;
1266                 default:
1267                     break;
1268             }
1269             break;
1270         case ATT_HANDLE_VALUE_INDICATION:
1271             if (size < 3u) break;
1272             report_gatt_indication(handle, little_endian_read_16(packet,1u), &packet[3], size-3u);
1273             gatt_client->send_confirmation = 1;
1274             break;
1275 
1276         case ATT_READ_BY_TYPE_RESPONSE:
1277             switch (gatt_client->gatt_client_state){
1278                 case P_W4_ALL_CHARACTERISTICS_OF_SERVICE_QUERY_RESULT:
1279                     report_gatt_characteristics(gatt_client, packet, size);
1280                     trigger_next_characteristic_query(gatt_client, get_last_result_handle_from_characteristics_list(packet, size));
1281                     // GATT_EVENT_QUERY_COMPLETE is emitted by trigger_next_xxx when done, or by ATT_ERROR
1282                     break;
1283                 case P_W4_CHARACTERISTIC_WITH_UUID_QUERY_RESULT:
1284                     report_gatt_characteristics(gatt_client, packet, size);
1285                     trigger_next_characteristic_query(gatt_client, get_last_result_handle_from_characteristics_list(packet, size));
1286                     // GATT_EVENT_QUERY_COMPLETE is emitted by trigger_next_xxx when done, or by ATT_ERROR
1287                     break;
1288                 case P_W4_INCLUDED_SERVICE_QUERY_RESULT:
1289                 {
1290                     if (size < 2u) break;
1291                     uint16_t uuid16 = 0;
1292                     uint16_t pair_size = packet[1];
1293 
1294                     if (pair_size == 6u){
1295                         if (size < 8u) break;
1296                         // UUIDs not available, query first included service
1297                         gatt_client->start_group_handle = little_endian_read_16(packet, 2); // ready for next query
1298                         gatt_client->query_start_handle = little_endian_read_16(packet, 4);
1299                         gatt_client->query_end_handle = little_endian_read_16(packet, 6);
1300                         gatt_client->gatt_client_state = P_W2_SEND_INCLUDED_SERVICE_WITH_UUID_QUERY;
1301                         break;
1302                     }
1303 
1304                     if (pair_size != 8u) break;
1305 
1306                     // UUIDs included, report all of them
1307                     uint16_t offset;
1308                     for (offset = 2u; (offset + 8u) <= size; offset += pair_size){
1309                         uint16_t include_handle = little_endian_read_16(packet, offset);
1310                         gatt_client->query_start_handle = little_endian_read_16(packet, offset + 2u);
1311                         gatt_client->query_end_handle = little_endian_read_16(packet, offset + 4u);
1312                         uuid16 = little_endian_read_16(packet, offset+6u);
1313                         report_gatt_included_service_uuid16(gatt_client, include_handle, uuid16);
1314                     }
1315 
1316                     trigger_next_included_service_query(gatt_client, get_last_result_handle_from_included_services_list(packet, size));
1317                     // GATT_EVENT_QUERY_COMPLETE is emitted by trigger_next_xxx when done
1318                     break;
1319                 }
1320 #ifndef ENABLE_GATT_FIND_INFORMATION_FOR_CCC_DISCOVERY
1321                 case P_W4_READ_CLIENT_CHARACTERISTIC_CONFIGURATION_QUERY_RESULT:
1322                     gatt_client->client_characteristic_configuration_handle = little_endian_read_16(packet, 2);
1323                     gatt_client->gatt_client_state = P_W2_WRITE_CLIENT_CHARACTERISTIC_CONFIGURATION;
1324                     break;
1325 #endif
1326                 case P_W4_READ_BY_TYPE_RESPONSE: {
1327                     uint16_t pair_size = packet[1];
1328                     uint16_t offset;
1329                     uint16_t last_result_handle = 0;
1330                     for (offset = 2; offset < size ; offset += pair_size){
1331                         uint16_t value_handle = little_endian_read_16(packet, offset);
1332                         report_gatt_characteristic_value(gatt_client, value_handle, &packet[offset + 2u], pair_size - 2u);
1333                         last_result_handle = value_handle;
1334                     }
1335                     trigger_next_read_by_type_query(gatt_client, last_result_handle);
1336                     break;
1337                 }
1338                 default:
1339                     break;
1340             }
1341             break;
1342         case ATT_READ_RESPONSE:
1343             switch (gatt_client->gatt_client_state){
1344                 case P_W4_INCLUDED_SERVICE_UUID_WITH_QUERY_RESULT: {
1345                     uint8_t uuid128[16];
1346                     reverse_128(&packet[1], uuid128);
1347                     report_gatt_included_service_uuid128(gatt_client, gatt_client->start_group_handle, uuid128);
1348                     trigger_next_included_service_query(gatt_client, gatt_client->start_group_handle);
1349                     // GATT_EVENT_QUERY_COMPLETE is emitted by trigger_next_xxx when done
1350                     break;
1351                 }
1352                 case P_W4_READ_CHARACTERISTIC_VALUE_RESULT:
1353                     gatt_client_handle_transaction_complete(gatt_client);
1354                     report_gatt_characteristic_value(gatt_client, gatt_client->attribute_handle, &packet[1], size - 1u);
1355                     emit_gatt_complete_event(gatt_client, ATT_ERROR_SUCCESS);
1356                     break;
1357 
1358                 case P_W4_READ_CHARACTERISTIC_DESCRIPTOR_RESULT:{
1359                     gatt_client_handle_transaction_complete(gatt_client);
1360                     report_gatt_characteristic_descriptor(gatt_client, gatt_client->attribute_handle, &packet[1], size - 1u, 0u);
1361                     emit_gatt_complete_event(gatt_client, ATT_ERROR_SUCCESS);
1362                     break;
1363                 }
1364                 default:
1365                     break;
1366             }
1367             break;
1368 
1369         case ATT_FIND_BY_TYPE_VALUE_RESPONSE:
1370         {
1371             uint8_t pair_size = 4;
1372             int i;
1373             uint16_t start_group_handle;
1374             uint16_t   end_group_handle= 0xffff; // asserts GATT_EVENT_QUERY_COMPLETE is emitted if no results
1375             for (i = 1u; (i + pair_size) <= size; i += pair_size){
1376                 start_group_handle = little_endian_read_16(packet,i);
1377                 end_group_handle = little_endian_read_16(packet,i+2);
1378                 emit_gatt_service_query_result_event(gatt_client, start_group_handle, end_group_handle, gatt_client->uuid128);
1379             }
1380             trigger_next_service_by_uuid_query(gatt_client, end_group_handle);
1381             // GATT_EVENT_QUERY_COMPLETE is emitted by trigger_next_xxx when done
1382             break;
1383         }
1384         case ATT_FIND_INFORMATION_REPLY:
1385         {
1386             if (size < 2u) break;
1387 
1388             uint8_t pair_size = 4;
1389             if (packet[1u] == 2u){
1390                 pair_size = 18;
1391             }
1392             uint16_t offset = 2;
1393 
1394             if (size < (pair_size + offset)) break;
1395             uint16_t last_descriptor_handle = little_endian_read_16(packet, size - pair_size);
1396 
1397 #ifdef ENABLE_GATT_FIND_INFORMATION_FOR_CCC_DISCOVERY
1398             log_info("ENABLE_GATT_FIND_INFORMATION_FOR_CCC_DISCOVERY, state %x", gatt_client->gatt_client_state);
1399             if (gatt_client->gatt_client_state == P_W4_FIND_CLIENT_CHARACTERISTIC_CONFIGURATION_QUERY_RESULT){
1400                 // iterate over descriptors looking for CCC
1401                 if (pair_size == 4){
1402                     while ((offset + 4) <= size){
1403                         uint16_t uuid16 = little_endian_read_16(packet, offset + 2);
1404                         if (uuid16 == GATT_CLIENT_CHARACTERISTICS_CONFIGURATION){
1405                             gatt_client->client_characteristic_configuration_handle = little_endian_read_16(packet, offset);
1406                             gatt_client->gatt_client_state = P_W2_WRITE_CLIENT_CHARACTERISTIC_CONFIGURATION;
1407                             log_info("CCC found %x", gatt_client->client_characteristic_configuration_handle);
1408                             break;
1409                         }
1410                         offset += pair_size;
1411                     }
1412                 }
1413                 if (is_query_done(gatt_client, last_descriptor_handle)){
1414 
1415                 } else {
1416                     // next
1417                     gatt_client->start_group_handle = last_descriptor_handle + 1;
1418                     gatt_client->gatt_client_state = P_W2_SEND_FIND_CLIENT_CHARACTERISTIC_CONFIGURATION_QUERY;
1419                 }
1420                 break;
1421             }
1422 #endif
1423             report_gatt_all_characteristic_descriptors(gatt_client, &packet[2], size - 2u, pair_size);
1424             trigger_next_characteristic_descriptor_query(gatt_client, last_descriptor_handle);
1425             // GATT_EVENT_QUERY_COMPLETE is emitted by trigger_next_xxx when done
1426             break;
1427         }
1428 
1429         case ATT_WRITE_RESPONSE:
1430             switch (gatt_client->gatt_client_state){
1431                 case P_W4_WRITE_CHARACTERISTIC_VALUE_RESULT:
1432                     gatt_client_handle_transaction_complete(gatt_client);
1433                     emit_gatt_complete_event(gatt_client, ATT_ERROR_SUCCESS);
1434                     break;
1435                 case P_W4_CLIENT_CHARACTERISTIC_CONFIGURATION_RESULT:
1436                     gatt_client_handle_transaction_complete(gatt_client);
1437                     emit_gatt_complete_event(gatt_client, ATT_ERROR_SUCCESS);
1438                     break;
1439                 case P_W4_WRITE_CHARACTERISTIC_DESCRIPTOR_RESULT:
1440                     gatt_client_handle_transaction_complete(gatt_client);
1441                     emit_gatt_complete_event(gatt_client, ATT_ERROR_SUCCESS);
1442                     break;
1443                 default:
1444                     break;
1445             }
1446             break;
1447 
1448         case ATT_READ_BLOB_RESPONSE:{
1449             uint16_t received_blob_length = size-1u;
1450             switch(gatt_client->gatt_client_state){
1451                 case P_W4_READ_BLOB_RESULT:
1452                     report_gatt_long_characteristic_value_blob(gatt_client, gatt_client->attribute_handle, &packet[1], received_blob_length, gatt_client->attribute_offset);
1453                     trigger_next_blob_query(gatt_client, P_W2_SEND_READ_BLOB_QUERY, received_blob_length);
1454                     // GATT_EVENT_QUERY_COMPLETE is emitted by trigger_next_xxx when done
1455                     break;
1456                 case P_W4_READ_BLOB_CHARACTERISTIC_DESCRIPTOR_RESULT:
1457                     report_gatt_long_characteristic_descriptor(gatt_client, gatt_client->attribute_handle,
1458                                                                &packet[1], received_blob_length,
1459                                                                gatt_client->attribute_offset);
1460                     trigger_next_blob_query(gatt_client, P_W2_SEND_READ_BLOB_CHARACTERISTIC_DESCRIPTOR_QUERY, received_blob_length);
1461                     // GATT_EVENT_QUERY_COMPLETE is emitted by trigger_next_xxx when done
1462                     break;
1463                 default:
1464                     break;
1465             }
1466             break;
1467         }
1468         case ATT_PREPARE_WRITE_RESPONSE:
1469             switch (gatt_client->gatt_client_state){
1470                 case P_W4_PREPARE_WRITE_SINGLE_RESULT:
1471                     gatt_client_handle_transaction_complete(gatt_client);
1472                     if (is_value_valid(gatt_client, packet, size)){
1473                         emit_gatt_complete_event(gatt_client, ATT_ERROR_SUCCESS);
1474                     } else {
1475                         emit_gatt_complete_event(gatt_client, ATT_ERROR_DATA_MISMATCH);
1476                     }
1477                     break;
1478 
1479                 case P_W4_PREPARE_WRITE_RESULT:{
1480                     gatt_client->attribute_offset = little_endian_read_16(packet, 3);
1481                     trigger_next_prepare_write_query(gatt_client, P_W2_PREPARE_WRITE, P_W2_EXECUTE_PREPARED_WRITE);
1482                     // GATT_EVENT_QUERY_COMPLETE is emitted by trigger_next_xxx when done
1483                     break;
1484                 }
1485                 case P_W4_PREPARE_WRITE_CHARACTERISTIC_DESCRIPTOR_RESULT:{
1486                     gatt_client->attribute_offset = little_endian_read_16(packet, 3);
1487                     trigger_next_prepare_write_query(gatt_client, P_W2_PREPARE_WRITE_CHARACTERISTIC_DESCRIPTOR, P_W2_EXECUTE_PREPARED_WRITE_CHARACTERISTIC_DESCRIPTOR);
1488                     // GATT_EVENT_QUERY_COMPLETE is emitted by trigger_next_xxx when done
1489                     break;
1490                 }
1491                 case P_W4_PREPARE_RELIABLE_WRITE_RESULT:{
1492                     if (is_value_valid(gatt_client, packet, size)){
1493                         gatt_client->attribute_offset = little_endian_read_16(packet, 3);
1494                         trigger_next_prepare_write_query(gatt_client, P_W2_PREPARE_RELIABLE_WRITE, P_W2_EXECUTE_PREPARED_WRITE);
1495                         // GATT_EVENT_QUERY_COMPLETE is emitted by trigger_next_xxx when done
1496                         break;
1497                     }
1498                     gatt_client->gatt_client_state = P_W2_CANCEL_PREPARED_WRITE_DATA_MISMATCH;
1499                     break;
1500                 }
1501                 default:
1502                     break;
1503             }
1504             break;
1505 
1506         case ATT_EXECUTE_WRITE_RESPONSE:
1507             switch (gatt_client->gatt_client_state){
1508                 case P_W4_EXECUTE_PREPARED_WRITE_RESULT:
1509                     gatt_client_handle_transaction_complete(gatt_client);
1510                     emit_gatt_complete_event(gatt_client, ATT_ERROR_SUCCESS);
1511                     break;
1512                 case P_W4_CANCEL_PREPARED_WRITE_RESULT:
1513                     gatt_client_handle_transaction_complete(gatt_client);
1514                     emit_gatt_complete_event(gatt_client, ATT_ERROR_SUCCESS);
1515                     break;
1516                 case P_W4_CANCEL_PREPARED_WRITE_DATA_MISMATCH_RESULT:
1517                     gatt_client_handle_transaction_complete(gatt_client);
1518                     emit_gatt_complete_event(gatt_client, ATT_ERROR_DATA_MISMATCH);
1519                     break;
1520                 case P_W4_EXECUTE_PREPARED_WRITE_CHARACTERISTIC_DESCRIPTOR_RESULT:
1521                     gatt_client_handle_transaction_complete(gatt_client);
1522                     emit_gatt_complete_event(gatt_client, ATT_ERROR_SUCCESS);
1523                     break;
1524                 default:
1525                     break;
1526 
1527             }
1528             break;
1529 
1530         case ATT_READ_MULTIPLE_RESPONSE:
1531             switch(gatt_client->gatt_client_state){
1532                 case P_W4_READ_MULTIPLE_RESPONSE:
1533                     report_gatt_characteristic_value(gatt_client, 0u, &packet[1], size - 1u);
1534                     gatt_client_handle_transaction_complete(gatt_client);
1535                     emit_gatt_complete_event(gatt_client, ATT_ERROR_SUCCESS);
1536                     break;
1537                 default:
1538                     break;
1539             }
1540             break;
1541 
1542         case ATT_ERROR_RESPONSE:
1543             if (size < 5u) return;
1544             error_code = packet[4];
1545             switch (error_code){
1546                 case ATT_ERROR_ATTRIBUTE_NOT_FOUND: {
1547                     switch(gatt_client->gatt_client_state){
1548                         case P_W4_SERVICE_QUERY_RESULT:
1549                         case P_W4_SERVICE_WITH_UUID_RESULT:
1550                         case P_W4_INCLUDED_SERVICE_QUERY_RESULT:
1551                         case P_W4_ALL_CHARACTERISTIC_DESCRIPTORS_QUERY_RESULT:
1552                             gatt_client_handle_transaction_complete(gatt_client);
1553                             emit_gatt_complete_event(gatt_client, ATT_ERROR_SUCCESS);
1554                             break;
1555                         case P_W4_ALL_CHARACTERISTICS_OF_SERVICE_QUERY_RESULT:
1556                         case P_W4_CHARACTERISTIC_WITH_UUID_QUERY_RESULT:
1557                             characteristic_end_found(gatt_client, gatt_client->end_group_handle);
1558                             gatt_client_handle_transaction_complete(gatt_client);
1559                             emit_gatt_complete_event(gatt_client, ATT_ERROR_SUCCESS);
1560                             break;
1561                         case P_W4_READ_BY_TYPE_RESPONSE:
1562                             gatt_client_handle_transaction_complete(gatt_client);
1563                             if (gatt_client->start_group_handle == gatt_client->query_start_handle){
1564                                 emit_gatt_complete_event(gatt_client, ATT_ERROR_ATTRIBUTE_NOT_FOUND);
1565                             } else {
1566                                 emit_gatt_complete_event(gatt_client, ATT_ERROR_SUCCESS);
1567                             }
1568                             break;
1569                         default:
1570                             gatt_client_report_error_if_pending(gatt_client, error_code);
1571                             break;
1572                     }
1573                     break;
1574                 }
1575 
1576 #ifdef ENABLE_GATT_CLIENT_PAIRING
1577 
1578                 case ATT_ERROR_INSUFFICIENT_AUTHENTICATION:
1579                 case ATT_ERROR_INSUFFICIENT_ENCRYPTION_KEY_SIZE:
1580                 case ATT_ERROR_INSUFFICIENT_ENCRYPTION: {
1581 
1582                     // security too low
1583                     if (gatt_client->security_counter > 0) {
1584                         gatt_client_report_error_if_pending(gatt_client, error_code);
1585                         break;
1586                     }
1587                     // start security
1588                     gatt_client->security_counter++;
1589 
1590                     // setup action
1591                     int retry = 1;
1592                     switch (gatt_client->gatt_client_state){
1593                         case P_W4_READ_CHARACTERISTIC_VALUE_RESULT:
1594                             gatt_client->gatt_client_state = P_W2_SEND_READ_CHARACTERISTIC_VALUE_QUERY ;
1595                             break;
1596                         case P_W4_READ_BLOB_RESULT:
1597                             gatt_client->gatt_client_state = P_W2_SEND_READ_BLOB_QUERY;
1598                             break;
1599                         case P_W4_READ_BY_TYPE_RESPONSE:
1600                             gatt_client->gatt_client_state = P_W2_SEND_READ_BY_TYPE_REQUEST;
1601                             break;
1602                         case P_W4_READ_MULTIPLE_RESPONSE:
1603                             gatt_client->gatt_client_state = P_W2_SEND_READ_MULTIPLE_REQUEST;
1604                             break;
1605                         case P_W4_WRITE_CHARACTERISTIC_VALUE_RESULT:
1606                             gatt_client->gatt_client_state = P_W2_SEND_WRITE_CHARACTERISTIC_VALUE;
1607                             break;
1608                         case P_W4_PREPARE_WRITE_RESULT:
1609                             gatt_client->gatt_client_state = P_W2_PREPARE_WRITE;
1610                             break;
1611                         case P_W4_PREPARE_WRITE_SINGLE_RESULT:
1612                             gatt_client->gatt_client_state = P_W2_PREPARE_WRITE_SINGLE;
1613                             break;
1614                         case P_W4_PREPARE_RELIABLE_WRITE_RESULT:
1615                             gatt_client->gatt_client_state = P_W2_PREPARE_RELIABLE_WRITE;
1616                             break;
1617                         case P_W4_EXECUTE_PREPARED_WRITE_RESULT:
1618                             gatt_client->gatt_client_state = P_W2_EXECUTE_PREPARED_WRITE;
1619                             break;
1620                         case P_W4_CANCEL_PREPARED_WRITE_RESULT:
1621                             gatt_client->gatt_client_state = P_W2_CANCEL_PREPARED_WRITE;
1622                             break;
1623                         case P_W4_CANCEL_PREPARED_WRITE_DATA_MISMATCH_RESULT:
1624                             gatt_client->gatt_client_state = P_W2_CANCEL_PREPARED_WRITE_DATA_MISMATCH;
1625                             break;
1626                         case P_W4_READ_CHARACTERISTIC_DESCRIPTOR_RESULT:
1627                             gatt_client->gatt_client_state = P_W2_SEND_READ_CHARACTERISTIC_DESCRIPTOR_QUERY;
1628                             break;
1629                         case P_W4_READ_BLOB_CHARACTERISTIC_DESCRIPTOR_RESULT:
1630                             gatt_client->gatt_client_state = P_W2_SEND_READ_BLOB_CHARACTERISTIC_DESCRIPTOR_QUERY;
1631                             break;
1632                         case P_W4_WRITE_CHARACTERISTIC_DESCRIPTOR_RESULT:
1633                             gatt_client->gatt_client_state = P_W2_SEND_WRITE_CHARACTERISTIC_DESCRIPTOR;
1634                             break;
1635                         case P_W4_CLIENT_CHARACTERISTIC_CONFIGURATION_RESULT:
1636                             gatt_client->gatt_client_state = P_W2_WRITE_CLIENT_CHARACTERISTIC_CONFIGURATION;
1637                             break;
1638                         case P_W4_PREPARE_WRITE_CHARACTERISTIC_DESCRIPTOR_RESULT:
1639                             gatt_client->gatt_client_state = P_W2_PREPARE_WRITE_CHARACTERISTIC_DESCRIPTOR;
1640                             break;
1641                         case P_W4_EXECUTE_PREPARED_WRITE_CHARACTERISTIC_DESCRIPTOR_RESULT:
1642                             gatt_client->gatt_client_state = P_W2_EXECUTE_PREPARED_WRITE_CHARACTERISTIC_DESCRIPTOR;
1643                             break;
1644 #ifdef ENABLE_LE_SIGNED_WRITE
1645                         case P_W4_SEND_SINGED_WRITE_DONE:
1646                             gatt_client->gatt_client_state = P_W2_SEND_SIGNED_WRITE;
1647                             break;
1648 #endif
1649                         default:
1650                             log_info("retry not supported for state %x", gatt_client->gatt_client_state);
1651                             retry = 0;
1652                             break;
1653                     }
1654 
1655                     if (!retry) {
1656                         gatt_client_report_error_if_pending(gatt_client, error_code);
1657                         break;
1658                     }
1659 
1660                     log_info("security error, start pairing");
1661 
1662                     // start pairing for higher security level
1663                     gatt_client->wait_for_pairing_complete = 1;
1664                     gatt_client->pending_error_code = error_code;
1665                     sm_request_pairing(gatt_client->con_handle);
1666                     break;
1667                 }
1668 #endif
1669 
1670                 // nothing we can do about that
1671                 case ATT_ERROR_INSUFFICIENT_AUTHORIZATION:
1672                 default:
1673                     gatt_client_report_error_if_pending(gatt_client, error_code);
1674                     break;
1675             }
1676             break;
1677 
1678         default:
1679             log_info("ATT Handler, unhandled response type 0x%02x", packet[0]);
1680             break;
1681     }
1682     gatt_client_run();
1683 }
1684 
1685 #ifdef ENABLE_LE_SIGNED_WRITE
1686 static void att_signed_write_handle_cmac_result(uint8_t hash[8]){
1687     btstack_linked_list_iterator_t it;
1688     btstack_linked_list_iterator_init(&it, &gatt_client_connections);
1689     while (btstack_linked_list_iterator_has_next(&it)){
1690         gatt_client_t * gatt_client = (gatt_client_t *) btstack_linked_list_iterator_next(&it);
1691         if (gatt_client->gatt_client_state == P_W4_CMAC_RESULT){
1692             // store result
1693             (void)memcpy(gatt_client->cmac, hash, 8);
1694             // reverse_64(hash, gatt_client->cmac);
1695             gatt_client->gatt_client_state = P_W2_SEND_SIGNED_WRITE;
1696             gatt_client_run();
1697             return;
1698         }
1699     }
1700 }
1701 
1702 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){
1703     gatt_client_t * gatt_client = gatt_client_provide_context_for_handle(con_handle);
1704     if (gatt_client == NULL) return BTSTACK_MEMORY_ALLOC_FAILED;
1705     if (is_ready(gatt_client) == 0) return GATT_CLIENT_IN_WRONG_STATE;
1706 
1707     gatt_client->callback = callback;
1708     gatt_client->attribute_handle = handle;
1709     gatt_client->attribute_length = message_len;
1710     gatt_client->attribute_value = message;
1711     gatt_client->gatt_client_state = P_W4_IDENTITY_RESOLVING;
1712     gatt_client_run();
1713     return ERROR_CODE_SUCCESS;
1714 }
1715 #endif
1716 
1717 uint8_t gatt_client_discover_primary_services(btstack_packet_handler_t callback, hci_con_handle_t con_handle){
1718     gatt_client_t * gatt_client = gatt_client_provide_context_for_handle_and_start_timer(con_handle);
1719     if (gatt_client == NULL) return BTSTACK_MEMORY_ALLOC_FAILED;
1720     if (is_ready(gatt_client) == 0) return GATT_CLIENT_IN_WRONG_STATE;
1721 
1722     gatt_client->callback = callback;
1723     gatt_client->start_group_handle = 0x0001;
1724     gatt_client->end_group_handle   = 0xffff;
1725     gatt_client->gatt_client_state = P_W2_SEND_SERVICE_QUERY;
1726     gatt_client->uuid16 = 0;
1727     gatt_client_run();
1728     return ERROR_CODE_SUCCESS;
1729 }
1730 
1731 
1732 uint8_t gatt_client_discover_primary_services_by_uuid16(btstack_packet_handler_t callback, hci_con_handle_t con_handle, uint16_t uuid16){
1733     gatt_client_t * gatt_client = gatt_client_provide_context_for_handle_and_start_timer(con_handle);
1734     if (gatt_client == NULL) return BTSTACK_MEMORY_ALLOC_FAILED;
1735     if (is_ready(gatt_client) == 0) return GATT_CLIENT_IN_WRONG_STATE;
1736 
1737     gatt_client->callback = callback;
1738     gatt_client->start_group_handle = 0x0001;
1739     gatt_client->end_group_handle   = 0xffff;
1740     gatt_client->gatt_client_state = P_W2_SEND_SERVICE_WITH_UUID_QUERY;
1741     gatt_client->uuid16 = uuid16;
1742     uuid_add_bluetooth_prefix((uint8_t*) &(gatt_client->uuid128), gatt_client->uuid16);
1743     gatt_client_run();
1744     return ERROR_CODE_SUCCESS;
1745 }
1746 
1747 uint8_t gatt_client_discover_primary_services_by_uuid128(btstack_packet_handler_t callback, hci_con_handle_t con_handle, const uint8_t * uuid128){
1748     gatt_client_t * gatt_client = gatt_client_provide_context_for_handle_and_start_timer(con_handle);
1749     if (gatt_client == NULL) return BTSTACK_MEMORY_ALLOC_FAILED;
1750     if (is_ready(gatt_client) == 0) return GATT_CLIENT_IN_WRONG_STATE;
1751 
1752     gatt_client->callback = callback;
1753     gatt_client->start_group_handle = 0x0001;
1754     gatt_client->end_group_handle   = 0xffff;
1755     gatt_client->uuid16 = 0;
1756     (void)memcpy(gatt_client->uuid128, uuid128, 16);
1757     gatt_client->gatt_client_state = P_W2_SEND_SERVICE_WITH_UUID_QUERY;
1758     gatt_client_run();
1759     return ERROR_CODE_SUCCESS;
1760 }
1761 
1762 uint8_t gatt_client_discover_characteristics_for_service(btstack_packet_handler_t callback, hci_con_handle_t con_handle, gatt_client_service_t *service){
1763     gatt_client_t * gatt_client = gatt_client_provide_context_for_handle_and_start_timer(con_handle);
1764     if (gatt_client == NULL) return BTSTACK_MEMORY_ALLOC_FAILED;
1765     if (is_ready(gatt_client) == 0) return GATT_CLIENT_IN_WRONG_STATE;
1766 
1767     gatt_client->callback = callback;
1768     gatt_client->start_group_handle = service->start_group_handle;
1769     gatt_client->end_group_handle   = service->end_group_handle;
1770     gatt_client->filter_with_uuid = 0;
1771     gatt_client->characteristic_start_handle = 0;
1772     gatt_client->gatt_client_state = P_W2_SEND_ALL_CHARACTERISTICS_OF_SERVICE_QUERY;
1773     gatt_client_run();
1774     return ERROR_CODE_SUCCESS;
1775 }
1776 
1777 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){
1778     gatt_client_t * gatt_client = gatt_client_provide_context_for_handle_and_start_timer(con_handle);
1779     if (gatt_client == NULL) return BTSTACK_MEMORY_ALLOC_FAILED;
1780     if (is_ready(gatt_client) == 0) return GATT_CLIENT_IN_WRONG_STATE;
1781     gatt_client->callback = callback;
1782     gatt_client->start_group_handle = service->start_group_handle;
1783     gatt_client->end_group_handle   = service->end_group_handle;
1784     gatt_client->gatt_client_state = P_W2_SEND_INCLUDED_SERVICE_QUERY;
1785 
1786     gatt_client_run();
1787     return ERROR_CODE_SUCCESS;
1788 }
1789 
1790 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){
1791     gatt_client_t * gatt_client = gatt_client_provide_context_for_handle_and_start_timer(con_handle);
1792     if (gatt_client == NULL) return BTSTACK_MEMORY_ALLOC_FAILED;
1793     if (is_ready(gatt_client) == 0) return GATT_CLIENT_IN_WRONG_STATE;
1794 
1795     gatt_client->callback = callback;
1796     gatt_client->start_group_handle = start_handle;
1797     gatt_client->end_group_handle   = end_handle;
1798     gatt_client->filter_with_uuid = 1;
1799     gatt_client->uuid16 = uuid16;
1800     uuid_add_bluetooth_prefix((uint8_t*) &(gatt_client->uuid128), uuid16);
1801     gatt_client->characteristic_start_handle = 0;
1802     gatt_client->gatt_client_state = P_W2_SEND_CHARACTERISTIC_WITH_UUID_QUERY;
1803     gatt_client_run();
1804     return ERROR_CODE_SUCCESS;
1805 }
1806 
1807 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){
1808     gatt_client_t * gatt_client = gatt_client_provide_context_for_handle_and_start_timer(con_handle);
1809     if (gatt_client == NULL) return BTSTACK_MEMORY_ALLOC_FAILED;
1810     if (is_ready(gatt_client) == 0) return GATT_CLIENT_IN_WRONG_STATE;
1811 
1812     gatt_client->callback = callback;
1813     gatt_client->start_group_handle = start_handle;
1814     gatt_client->end_group_handle   = end_handle;
1815     gatt_client->filter_with_uuid = 1;
1816     gatt_client->uuid16 = 0;
1817     (void)memcpy(gatt_client->uuid128, uuid128, 16);
1818     gatt_client->characteristic_start_handle = 0;
1819     gatt_client->gatt_client_state = P_W2_SEND_CHARACTERISTIC_WITH_UUID_QUERY;
1820     gatt_client_run();
1821     return ERROR_CODE_SUCCESS;
1822 }
1823 
1824 
1825 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){
1826     return gatt_client_discover_characteristics_for_handle_range_by_uuid16(callback, handle, service->start_group_handle, service->end_group_handle, uuid16);
1827 }
1828 
1829 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){
1830     return gatt_client_discover_characteristics_for_handle_range_by_uuid128(callback, handle, service->start_group_handle, service->end_group_handle, uuid128);
1831 }
1832 
1833 uint8_t gatt_client_discover_characteristic_descriptors(btstack_packet_handler_t callback, hci_con_handle_t con_handle, gatt_client_characteristic_t *characteristic){
1834     gatt_client_t * gatt_client = gatt_client_provide_context_for_handle_and_start_timer(con_handle);
1835     if (gatt_client == NULL) return BTSTACK_MEMORY_ALLOC_FAILED;
1836     if (is_ready(gatt_client) == 0) return GATT_CLIENT_IN_WRONG_STATE;
1837 
1838     if (characteristic->value_handle == characteristic->end_handle){
1839         emit_gatt_complete_event(gatt_client, ATT_ERROR_SUCCESS);
1840         return ERROR_CODE_SUCCESS;
1841     }
1842     gatt_client->callback = callback;
1843     gatt_client->start_group_handle = characteristic->value_handle + 1u;
1844     gatt_client->end_group_handle   = characteristic->end_handle;
1845     gatt_client->gatt_client_state = P_W2_SEND_ALL_CHARACTERISTIC_DESCRIPTORS_QUERY;
1846     gatt_client_run();
1847     return ERROR_CODE_SUCCESS;
1848 }
1849 
1850 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){
1851     gatt_client_t * gatt_client = gatt_client_provide_context_for_handle_and_start_timer(con_handle);
1852     if (gatt_client == NULL) return BTSTACK_MEMORY_ALLOC_FAILED;
1853     if (is_ready(gatt_client) == 0) return GATT_CLIENT_IN_WRONG_STATE;
1854 
1855     gatt_client->callback = callback;
1856     gatt_client->attribute_handle = value_handle;
1857     gatt_client->attribute_offset = 0;
1858     gatt_client->gatt_client_state = P_W2_SEND_READ_CHARACTERISTIC_VALUE_QUERY;
1859     gatt_client_run();
1860     return ERROR_CODE_SUCCESS;
1861 }
1862 
1863 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){
1864     gatt_client_t * gatt_client = gatt_client_provide_context_for_handle_and_start_timer(con_handle);
1865     if (gatt_client == NULL) return BTSTACK_MEMORY_ALLOC_FAILED;
1866     if (is_ready(gatt_client) == 0) return GATT_CLIENT_IN_WRONG_STATE;
1867 
1868     gatt_client->callback = callback;
1869     gatt_client->start_group_handle = start_handle;
1870     gatt_client->end_group_handle = end_handle;
1871     gatt_client->query_start_handle = start_handle;
1872     gatt_client->query_end_handle = end_handle;
1873     gatt_client->uuid16 = uuid16;
1874     uuid_add_bluetooth_prefix((uint8_t*) &(gatt_client->uuid128), uuid16);
1875     gatt_client->gatt_client_state = P_W2_SEND_READ_BY_TYPE_REQUEST;
1876     gatt_client_run();
1877     return ERROR_CODE_SUCCESS;
1878 }
1879 
1880 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){
1881     gatt_client_t * gatt_client = gatt_client_provide_context_for_handle_and_start_timer(con_handle);
1882     if (gatt_client == NULL) return BTSTACK_MEMORY_ALLOC_FAILED;
1883     if (is_ready(gatt_client) == 0) return GATT_CLIENT_IN_WRONG_STATE;
1884 
1885     gatt_client->callback = callback;
1886     gatt_client->start_group_handle = start_handle;
1887     gatt_client->end_group_handle = end_handle;
1888     gatt_client->query_start_handle = start_handle;
1889     gatt_client->query_end_handle = end_handle;
1890     gatt_client->uuid16 = 0;
1891     (void)memcpy(gatt_client->uuid128, uuid128, 16);
1892     gatt_client->gatt_client_state = P_W2_SEND_READ_BY_TYPE_REQUEST;
1893     gatt_client_run();
1894     return ERROR_CODE_SUCCESS;
1895 }
1896 
1897 
1898 uint8_t gatt_client_read_value_of_characteristic(btstack_packet_handler_t callback, uint16_t handle, gatt_client_characteristic_t *characteristic){
1899     return gatt_client_read_value_of_characteristic_using_value_handle(callback, handle, characteristic->value_handle);
1900 }
1901 
1902 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){
1903     gatt_client_t * gatt_client = gatt_client_provide_context_for_handle_and_start_timer(con_handle);
1904     if (gatt_client == NULL) return BTSTACK_MEMORY_ALLOC_FAILED;
1905     if (is_ready(gatt_client) == 0) return GATT_CLIENT_IN_WRONG_STATE;
1906 
1907     gatt_client->callback = callback;
1908     gatt_client->attribute_handle = characteristic_value_handle;
1909     gatt_client->attribute_offset = offset;
1910     gatt_client->gatt_client_state = P_W2_SEND_READ_BLOB_QUERY;
1911     gatt_client_run();
1912     return ERROR_CODE_SUCCESS;
1913 }
1914 
1915 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){
1916     return gatt_client_read_long_value_of_characteristic_using_value_handle_with_offset(callback, con_handle, characteristic_value_handle, 0);
1917 }
1918 
1919 uint8_t gatt_client_read_long_value_of_characteristic(btstack_packet_handler_t callback, uint16_t handle, gatt_client_characteristic_t *characteristic){
1920     return gatt_client_read_long_value_of_characteristic_using_value_handle(callback, handle, characteristic->value_handle);
1921 }
1922 
1923 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){
1924     gatt_client_t * gatt_client = gatt_client_provide_context_for_handle_and_start_timer(con_handle);
1925     if (gatt_client == NULL) return BTSTACK_MEMORY_ALLOC_FAILED;
1926     if (is_ready(gatt_client) == 0) return GATT_CLIENT_IN_WRONG_STATE;
1927 
1928     gatt_client->callback = callback;
1929     gatt_client->read_multiple_handle_count = num_value_handles;
1930     gatt_client->read_multiple_handles = value_handles;
1931     gatt_client->gatt_client_state = P_W2_SEND_READ_MULTIPLE_REQUEST;
1932     gatt_client_run();
1933     return ERROR_CODE_SUCCESS;
1934 }
1935 
1936 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){
1937     gatt_client_t * gatt_client = gatt_client_provide_context_for_handle(con_handle);
1938     if (gatt_client == NULL) return BTSTACK_MEMORY_ALLOC_FAILED;
1939 
1940     if (value_length > (gatt_client->mtu - 3u)) return GATT_CLIENT_VALUE_TOO_LONG;
1941     if (!att_dispatch_client_can_send_now(gatt_client->con_handle)) return GATT_CLIENT_BUSY;
1942 
1943     return att_write_request(ATT_WRITE_COMMAND, gatt_client->con_handle, value_handle, value_length, value);
1944 }
1945 
1946 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){
1947     gatt_client_t * gatt_client = gatt_client_provide_context_for_handle_and_start_timer(con_handle);
1948     if (gatt_client == NULL) return BTSTACK_MEMORY_ALLOC_FAILED;
1949     if (is_ready(gatt_client) == 0) return GATT_CLIENT_IN_WRONG_STATE;
1950 
1951     gatt_client->callback = callback;
1952     gatt_client->attribute_handle = value_handle;
1953     gatt_client->attribute_length = value_length;
1954     gatt_client->attribute_value = data;
1955     gatt_client->gatt_client_state = P_W2_SEND_WRITE_CHARACTERISTIC_VALUE;
1956     gatt_client_run();
1957     return ERROR_CODE_SUCCESS;
1958 }
1959 
1960 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){
1961     gatt_client_t * gatt_client = gatt_client_provide_context_for_handle_and_start_timer(con_handle);
1962     if (gatt_client == NULL) return BTSTACK_MEMORY_ALLOC_FAILED;
1963     if (is_ready(gatt_client) == 0) return GATT_CLIENT_IN_WRONG_STATE;
1964 
1965     gatt_client->callback = callback;
1966     gatt_client->attribute_handle = value_handle;
1967     gatt_client->attribute_length = value_length;
1968     gatt_client->attribute_offset = offset;
1969     gatt_client->attribute_value = data;
1970     gatt_client->gatt_client_state = P_W2_PREPARE_WRITE;
1971     gatt_client_run();
1972     return ERROR_CODE_SUCCESS;
1973 }
1974 
1975 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){
1976     return gatt_client_write_long_value_of_characteristic_with_offset(callback, con_handle, value_handle, 0, value_length, value);
1977 }
1978 
1979 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){
1980     gatt_client_t * gatt_client = gatt_client_provide_context_for_handle_and_start_timer(con_handle);
1981     if (gatt_client == NULL) return BTSTACK_MEMORY_ALLOC_FAILED;
1982     if (is_ready(gatt_client) == 0) return GATT_CLIENT_IN_WRONG_STATE;
1983 
1984     gatt_client->callback = callback;
1985     gatt_client->attribute_handle = value_handle;
1986     gatt_client->attribute_length = value_length;
1987     gatt_client->attribute_offset = 0;
1988     gatt_client->attribute_value = value;
1989     gatt_client->gatt_client_state = P_W2_PREPARE_RELIABLE_WRITE;
1990     gatt_client_run();
1991     return ERROR_CODE_SUCCESS;
1992 }
1993 
1994 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){
1995     gatt_client_t * gatt_client = gatt_client_provide_context_for_handle_and_start_timer(con_handle);
1996     if (gatt_client == NULL) return BTSTACK_MEMORY_ALLOC_FAILED;
1997     if (is_ready(gatt_client) == 0) return GATT_CLIENT_IN_WRONG_STATE;
1998 
1999     if ( (configuration & GATT_CLIENT_CHARACTERISTICS_CONFIGURATION_NOTIFICATION) &&
2000         ((characteristic->properties & ATT_PROPERTY_NOTIFY) == 0u)) {
2001         log_info("gatt_client_write_client_characteristic_configuration: GATT_CLIENT_CHARACTERISTIC_NOTIFICATION_NOT_SUPPORTED");
2002         return GATT_CLIENT_CHARACTERISTIC_NOTIFICATION_NOT_SUPPORTED;
2003     } else if ( (configuration & GATT_CLIENT_CHARACTERISTICS_CONFIGURATION_INDICATION) &&
2004                ((characteristic->properties & ATT_PROPERTY_INDICATE) == 0u)){
2005         log_info("gatt_client_write_client_characteristic_configuration: GATT_CLIENT_CHARACTERISTIC_INDICATION_NOT_SUPPORTED");
2006         return GATT_CLIENT_CHARACTERISTIC_INDICATION_NOT_SUPPORTED;
2007     }
2008 
2009     gatt_client->callback = callback;
2010     gatt_client->start_group_handle = characteristic->value_handle;
2011     gatt_client->end_group_handle = characteristic->end_handle;
2012     little_endian_store_16(gatt_client->client_characteristic_configuration_value, 0, configuration);
2013 
2014 #ifdef ENABLE_GATT_FIND_INFORMATION_FOR_CCC_DISCOVERY
2015     gatt_client->gatt_client_state = P_W2_SEND_FIND_CLIENT_CHARACTERISTIC_CONFIGURATION_QUERY;
2016 #else
2017     gatt_client->gatt_client_state = P_W2_SEND_READ_CLIENT_CHARACTERISTIC_CONFIGURATION_QUERY;
2018 #endif
2019     gatt_client_run();
2020     return ERROR_CODE_SUCCESS;
2021 }
2022 
2023 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){
2024     gatt_client_t * gatt_client = gatt_client_provide_context_for_handle_and_start_timer(con_handle);
2025     if (gatt_client == NULL) return BTSTACK_MEMORY_ALLOC_FAILED;
2026     if (is_ready(gatt_client) == 0) return GATT_CLIENT_IN_WRONG_STATE;
2027 
2028     gatt_client->callback = callback;
2029     gatt_client->attribute_handle = descriptor_handle;
2030 
2031     gatt_client->gatt_client_state = P_W2_SEND_READ_CHARACTERISTIC_DESCRIPTOR_QUERY;
2032     gatt_client_run();
2033     return ERROR_CODE_SUCCESS;
2034 }
2035 
2036 uint8_t gatt_client_read_characteristic_descriptor(btstack_packet_handler_t callback, hci_con_handle_t con_handle, gatt_client_characteristic_descriptor_t * descriptor){
2037     return gatt_client_read_characteristic_descriptor_using_descriptor_handle(callback, con_handle, descriptor->handle);
2038 }
2039 
2040 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){
2041     gatt_client_t * gatt_client = gatt_client_provide_context_for_handle_and_start_timer(con_handle);
2042     if (gatt_client == NULL) return BTSTACK_MEMORY_ALLOC_FAILED;
2043     if (is_ready(gatt_client) == 0) return GATT_CLIENT_IN_WRONG_STATE;
2044 
2045     gatt_client->callback = callback;
2046     gatt_client->attribute_handle = descriptor_handle;
2047     gatt_client->attribute_offset = offset;
2048     gatt_client->gatt_client_state = P_W2_SEND_READ_BLOB_CHARACTERISTIC_DESCRIPTOR_QUERY;
2049     gatt_client_run();
2050     return ERROR_CODE_SUCCESS;
2051 }
2052 
2053 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){
2054     return gatt_client_read_long_characteristic_descriptor_using_descriptor_handle_with_offset(callback, con_handle, descriptor_handle, 0);
2055 }
2056 
2057 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){
2058     return gatt_client_read_long_characteristic_descriptor_using_descriptor_handle(callback, con_handle, descriptor->handle);
2059 }
2060 
2061 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){
2062     gatt_client_t * gatt_client = gatt_client_provide_context_for_handle_and_start_timer(con_handle);
2063     if (gatt_client == NULL) return BTSTACK_MEMORY_ALLOC_FAILED;
2064     if (is_ready(gatt_client) == 0) return GATT_CLIENT_IN_WRONG_STATE;
2065 
2066     gatt_client->callback = callback;
2067     gatt_client->attribute_handle = descriptor_handle;
2068     gatt_client->attribute_length = length;
2069     gatt_client->attribute_offset = 0;
2070     gatt_client->attribute_value = data;
2071     gatt_client->gatt_client_state = P_W2_SEND_WRITE_CHARACTERISTIC_DESCRIPTOR;
2072     gatt_client_run();
2073     return ERROR_CODE_SUCCESS;
2074 }
2075 
2076 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){
2077     return gatt_client_write_characteristic_descriptor_using_descriptor_handle(callback, con_handle, descriptor->handle, length, value);
2078 }
2079 
2080 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){
2081     gatt_client_t * gatt_client = gatt_client_provide_context_for_handle_and_start_timer(con_handle);
2082     if (gatt_client == NULL) return BTSTACK_MEMORY_ALLOC_FAILED;
2083     if (is_ready(gatt_client) == 0) return GATT_CLIENT_IN_WRONG_STATE;
2084 
2085     gatt_client->callback = callback;
2086     gatt_client->attribute_handle = descriptor_handle;
2087     gatt_client->attribute_length = length;
2088     gatt_client->attribute_offset = offset;
2089     gatt_client->attribute_value = data;
2090     gatt_client->gatt_client_state = P_W2_PREPARE_WRITE_CHARACTERISTIC_DESCRIPTOR;
2091     gatt_client_run();
2092     return ERROR_CODE_SUCCESS;
2093 }
2094 
2095 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){
2096     return gatt_client_write_long_characteristic_descriptor_using_descriptor_handle_with_offset(callback, con_handle, descriptor_handle, 0, length, data );
2097 }
2098 
2099 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){
2100     return gatt_client_write_long_characteristic_descriptor_using_descriptor_handle(callback, con_handle, descriptor->handle, length, value);
2101 }
2102 
2103 /**
2104  * @brief -> gatt complete event
2105  */
2106 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){
2107     gatt_client_t * gatt_client = gatt_client_provide_context_for_handle_and_start_timer(con_handle);
2108     if (gatt_client == NULL) return BTSTACK_MEMORY_ALLOC_FAILED;
2109     if (is_ready(gatt_client) == 0) return GATT_CLIENT_IN_WRONG_STATE;
2110 
2111     gatt_client->callback = callback;
2112     gatt_client->attribute_handle = attribute_handle;
2113     gatt_client->attribute_length = length;
2114     gatt_client->attribute_offset = offset;
2115     gatt_client->attribute_value = data;
2116     gatt_client->gatt_client_state = P_W2_PREPARE_WRITE_SINGLE;
2117     gatt_client_run();
2118     return ERROR_CODE_SUCCESS;
2119 }
2120 
2121 /**
2122  * @brief -> gatt complete event
2123  */
2124 uint8_t gatt_client_execute_write(btstack_packet_handler_t callback, hci_con_handle_t con_handle){
2125     gatt_client_t * gatt_client = gatt_client_provide_context_for_handle_and_start_timer(con_handle);
2126 
2127     if (gatt_client == NULL) return BTSTACK_MEMORY_ALLOC_FAILED;
2128     if (is_ready(gatt_client) == 0) return GATT_CLIENT_IN_WRONG_STATE;
2129 
2130     gatt_client->callback = callback;
2131     gatt_client->gatt_client_state = P_W2_EXECUTE_PREPARED_WRITE;
2132     gatt_client_run();
2133     return ERROR_CODE_SUCCESS;
2134 }
2135 
2136 /**
2137  * @brief -> gatt complete event
2138  */
2139 uint8_t gatt_client_cancel_write(btstack_packet_handler_t callback, hci_con_handle_t con_handle){
2140     gatt_client_t * gatt_client = gatt_client_provide_context_for_handle_and_start_timer(con_handle);
2141     if (gatt_client == NULL) return BTSTACK_MEMORY_ALLOC_FAILED;
2142     if (is_ready(gatt_client) == 0) return GATT_CLIENT_IN_WRONG_STATE;
2143 
2144     gatt_client->callback = callback;
2145     gatt_client->gatt_client_state = P_W2_CANCEL_PREPARED_WRITE;
2146     gatt_client_run();
2147     return ERROR_CODE_SUCCESS;
2148 }
2149 
2150 void gatt_client_deserialize_service(const uint8_t *packet, int offset, gatt_client_service_t *service){
2151     service->start_group_handle = little_endian_read_16(packet, offset);
2152     service->end_group_handle = little_endian_read_16(packet, offset + 2);
2153     reverse_128(&packet[offset + 4], service->uuid128);
2154     if (uuid_has_bluetooth_prefix(service->uuid128)){
2155         service->uuid16 = big_endian_read_32(service->uuid128, 0);
2156     } else {
2157         service->uuid16 = 0;
2158     }
2159 }
2160 
2161 void gatt_client_deserialize_characteristic(const uint8_t * packet, int offset, gatt_client_characteristic_t * characteristic){
2162     characteristic->start_handle = little_endian_read_16(packet, offset);
2163     characteristic->value_handle = little_endian_read_16(packet, offset + 2);
2164     characteristic->end_handle = little_endian_read_16(packet, offset + 4);
2165     characteristic->properties = little_endian_read_16(packet, offset + 6);
2166     reverse_128(&packet[offset+8], characteristic->uuid128);
2167     if (uuid_has_bluetooth_prefix(characteristic->uuid128)){
2168         characteristic->uuid16 = big_endian_read_32(characteristic->uuid128, 0);
2169     } else {
2170         characteristic->uuid16 = 0;
2171     }
2172 }
2173 
2174 void gatt_client_deserialize_characteristic_descriptor(const uint8_t * packet, int offset, gatt_client_characteristic_descriptor_t * descriptor){
2175     descriptor->handle = little_endian_read_16(packet, offset);
2176     reverse_128(&packet[offset+2], descriptor->uuid128);
2177     if (uuid_has_bluetooth_prefix(descriptor->uuid128)){
2178         descriptor->uuid16 = big_endian_read_32(descriptor->uuid128, 0);
2179     } else {
2180         descriptor->uuid16 = 0;
2181     }
2182 }
2183 
2184 void gatt_client_send_mtu_negotiation(btstack_packet_handler_t callback, hci_con_handle_t con_handle){
2185     gatt_client_t * context = gatt_client_provide_context_for_handle(con_handle);
2186     if (context == NULL) return;
2187     if (context->mtu_state == MTU_AUTO_EXCHANGE_DISABLED){
2188         context->callback = callback;
2189         context->mtu_state = SEND_MTU_EXCHANGE;
2190         gatt_client_run();
2191     }
2192 }
2193 
2194 uint8_t gatt_client_request_can_write_without_response_event(btstack_packet_handler_t callback, hci_con_handle_t con_handle){
2195     gatt_client_t * context = gatt_client_provide_context_for_handle(con_handle);
2196     if (context == NULL) return BTSTACK_MEMORY_ALLOC_FAILED;
2197     if (context->write_without_response_callback != NULL) return GATT_CLIENT_IN_WRONG_STATE;
2198     context->write_without_response_callback = callback;
2199     att_dispatch_client_request_can_send_now_event(context->con_handle);
2200     return ERROR_CODE_SUCCESS;
2201 }
2202 
2203 #ifdef FUZZING_BUILD_MODE_UNSAFE_FOR_PRODUCTION
2204 void gatt_client_att_packet_handler_fuzz(uint8_t packet_type, uint16_t handle, uint8_t *packet, uint16_t size){
2205     gatt_client_att_packet_handler(packet_type, handle, packet, size);
2206 }
2207 #endif
2208