xref: /btstack/src/ble/gatt_client.c (revision e9cdf30bbcdc3ad1eebaf0d535ba80c0cc39a66b)
1 /*
2  * Copyright (C) 2014 BlueKitchen GmbH
3  *
4  * Redistribution and use in source and binary forms, with or without
5  * modification, are permitted provided that the following conditions
6  * are met:
7  *
8  * 1. Redistributions of source code must retain the above copyright
9  *    notice, this list of conditions and the following disclaimer.
10  * 2. Redistributions in binary form must reproduce the above copyright
11  *    notice, this list of conditions and the following disclaimer in the
12  *    documentation and/or other materials provided with the distribution.
13  * 3. Neither the name of the copyright holders nor the names of
14  *    contributors may be used to endorse or promote products derived
15  *    from this software without specific prior written permission.
16  * 4. Any redistribution, use, or modification is done solely for
17  *    personal benefit and not for any commercial purpose or for
18  *    monetary gain.
19  *
20  * THIS SOFTWARE IS PROVIDED BY BLUEKITCHEN GMBH AND CONTRIBUTORS
21  * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
22  * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
23  * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL BLUEKITCHEN
24  * GMBH OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
25  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
26  * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
27  * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
28  * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
29  * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF
30  * THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
31  * SUCH DAMAGE.
32  *
33  * Please inquire about commercial licensing options at
34  * [email protected]
35  *
36  */
37 
38 #define BTSTACK_FILE__ "gatt_client.c"
39 
40 #include <stdint.h>
41 #include <string.h>
42 #include <stddef.h>
43 
44 #include "btstack_config.h"
45 
46 #include "ble/att_dispatch.h"
47 #include "ble/att_db.h"
48 #include "ble/gatt_client.h"
49 #include "ble/le_device_db.h"
50 #include "ble/sm.h"
51 #include "btstack_debug.h"
52 #include "btstack_event.h"
53 #include "btstack_memory.h"
54 #include "btstack_run_loop.h"
55 #include "btstack_util.h"
56 #include "hci.h"
57 #include "hci_dump.h"
58 #include "l2cap.h"
59 #include "classic/sdp_client.h"
60 #include "bluetooth_gatt.h"
61 #include "bluetooth_sdp.h"
62 #include "classic/sdp_util.h"
63 
64 static btstack_linked_list_t gatt_client_connections;
65 static btstack_linked_list_t gatt_client_value_listeners;
66 static btstack_packet_callback_registration_t hci_event_callback_registration;
67 static btstack_packet_callback_registration_t sm_event_callback_registration;
68 
69 // GATT Client Configuration
70 static bool                 gatt_client_mtu_exchange_enabled;
71 static gap_security_level_t gatt_client_required_security_level;
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 
84     // default configuration
85     gatt_client_mtu_exchange_enabled    = true;
86     gatt_client_required_security_level = LEVEL_0;
87 
88     // register for HCI Events
89     hci_event_callback_registration.callback = &gatt_client_event_packet_handler;
90     hci_add_event_handler(&hci_event_callback_registration);
91 
92     // register for SM Events
93     sm_event_callback_registration.callback = &gatt_client_event_packet_handler;
94     sm_add_event_handler(&sm_event_callback_registration);
95 
96     // and ATT Client PDUs
97     att_dispatch_register_client(gatt_client_att_packet_handler);
98 }
99 
100 void gatt_client_set_required_security_level(gap_security_level_t level){
101     gatt_client_required_security_level = level;
102 }
103 
104 static gatt_client_t * gatt_client_for_timer(btstack_timer_source_t * ts){
105     btstack_linked_list_iterator_t it;
106     btstack_linked_list_iterator_init(&it, &gatt_client_connections);
107     while (btstack_linked_list_iterator_has_next(&it)){
108         gatt_client_t * gatt_client = (gatt_client_t *) btstack_linked_list_iterator_next(&it);
109         if (&gatt_client->gc_timeout == ts) {
110             return gatt_client;
111         }
112     }
113     return NULL;
114 }
115 
116 static void gatt_client_timeout_handler(btstack_timer_source_t * timer){
117     gatt_client_t * gatt_client = gatt_client_for_timer(timer);
118     if (gatt_client == NULL) return;
119     log_info("GATT client timeout handle, handle 0x%02x", gatt_client->con_handle);
120     gatt_client_report_error_if_pending(gatt_client, ATT_ERROR_TIMEOUT);
121 }
122 
123 static void gatt_client_timeout_start(gatt_client_t * gatt_client){
124     log_info("GATT client timeout start, handle 0x%02x", gatt_client->con_handle);
125     btstack_run_loop_remove_timer(&gatt_client->gc_timeout);
126     btstack_run_loop_set_timer_handler(&gatt_client->gc_timeout, gatt_client_timeout_handler);
127     btstack_run_loop_set_timer(&gatt_client->gc_timeout, 30000); // 30 seconds sm timeout
128     btstack_run_loop_add_timer(&gatt_client->gc_timeout);
129 }
130 
131 static void gatt_client_timeout_stop(gatt_client_t * gatt_client){
132     log_info("GATT client timeout stop, handle 0x%02x", gatt_client->con_handle);
133     btstack_run_loop_remove_timer(&gatt_client->gc_timeout);
134 }
135 
136 static gap_security_level_t gatt_client_le_security_level_for_connection(hci_con_handle_t con_handle){
137     uint8_t encryption_key_size = gap_encryption_key_size(con_handle);
138     if (encryption_key_size == 0) return LEVEL_0;
139 
140     bool authenticated = gap_authenticated(con_handle);
141     if (!authenticated) return LEVEL_2;
142 
143     return encryption_key_size == 16 ? LEVEL_4 : LEVEL_3;
144 }
145 
146 static gatt_client_t * gatt_client_get_context_for_handle(uint16_t handle){
147     btstack_linked_item_t *it;
148     for (it = (btstack_linked_item_t *) gatt_client_connections; it != NULL; it = it->next){
149         gatt_client_t * gatt_client = (gatt_client_t *) it;
150         if (gatt_client->con_handle == handle){
151             return gatt_client;
152         }
153     }
154     return NULL;
155 }
156 
157 
158 // @return gatt_client context
159 // returns existing one, or tries to setup new one
160 static uint8_t gatt_client_provide_context_for_handle(hci_con_handle_t con_handle, gatt_client_t ** out_gatt_client){
161     gatt_client_t * gatt_client = gatt_client_get_context_for_handle(con_handle);
162 
163     if (gatt_client != NULL){
164         *out_gatt_client = gatt_client;
165         return ERROR_CODE_SUCCESS;
166     }
167 
168     // bail if no such hci connection
169     hci_connection_t * hci_connection = hci_connection_for_handle(con_handle);
170     if (hci_connection == NULL){
171         log_error("No connection for handle 0x%04x", con_handle);
172         *out_gatt_client = NULL;
173         return ERROR_CODE_UNKNOWN_CONNECTION_IDENTIFIER;
174     }
175 
176     gatt_client = btstack_memory_gatt_client_get();
177     if (gatt_client == NULL){
178         *out_gatt_client = NULL;
179         return ERROR_CODE_MEMORY_CAPACITY_EXCEEDED;
180     }
181     // init state
182     gatt_client->bearer_type = ATT_BEARER_UNENHANCED_LE;
183     gatt_client->con_handle = con_handle;
184     gatt_client->mtu = ATT_DEFAULT_MTU;
185     gatt_client->security_level = gatt_client_le_security_level_for_connection(con_handle);
186     if (gatt_client_mtu_exchange_enabled){
187         gatt_client->mtu_state = SEND_MTU_EXCHANGE;
188     } else {
189         gatt_client->mtu_state = MTU_AUTO_EXCHANGE_DISABLED;
190     }
191     gatt_client->gatt_client_state = P_READY;
192     btstack_linked_list_add(&gatt_client_connections, (btstack_linked_item_t*)gatt_client);
193 
194     // get unenhanced att bearer state
195     if (hci_connection->att_connection.mtu_exchanged){
196         gatt_client->mtu = hci_connection->att_connection.mtu;
197         gatt_client->mtu_state = MTU_EXCHANGED;
198     }
199     *out_gatt_client = gatt_client;
200     return ERROR_CODE_SUCCESS;
201 }
202 
203 static bool is_ready(gatt_client_t * gatt_client){
204     return gatt_client->gatt_client_state == P_READY;
205 }
206 
207 static uint8_t gatt_client_provide_context_for_request(hci_con_handle_t con_handle, gatt_client_t ** out_gatt_client){
208     gatt_client_t * gatt_client = NULL;
209     uint8_t status = gatt_client_provide_context_for_handle(con_handle, &gatt_client);
210     if (status != ERROR_CODE_SUCCESS){
211         return status;
212     }
213 
214     if (is_ready(gatt_client) == 0){
215         return GATT_CLIENT_IN_WRONG_STATE;
216     }
217 
218     gatt_client_timeout_start(gatt_client);
219 
220     *out_gatt_client = gatt_client;
221 
222     return status;
223 }
224 
225 int gatt_client_is_ready(hci_con_handle_t con_handle){
226     gatt_client_t * gatt_client;
227     uint8_t status = gatt_client_provide_context_for_handle(con_handle, &gatt_client);
228     if (status != ERROR_CODE_SUCCESS){
229         return 0;
230     }
231     return is_ready(gatt_client) ? 1 : 0;
232 }
233 
234 void gatt_client_mtu_enable_auto_negotiation(uint8_t enabled){
235     gatt_client_mtu_exchange_enabled = enabled != 0;
236 }
237 
238 uint8_t gatt_client_get_mtu(hci_con_handle_t con_handle, uint16_t * mtu){
239     gatt_client_t * gatt_client;
240     uint8_t status = gatt_client_provide_context_for_handle(con_handle, &gatt_client);
241     if (status != ERROR_CODE_SUCCESS){
242         return status;
243     }
244 
245     if ((gatt_client->mtu_state == MTU_EXCHANGED) || (gatt_client->mtu_state == MTU_AUTO_EXCHANGE_DISABLED)){
246         *mtu = gatt_client->mtu;
247         return ERROR_CODE_SUCCESS;
248     }
249     *mtu = ATT_DEFAULT_MTU;
250     return GATT_CLIENT_IN_WRONG_STATE;
251 }
252 
253 static uint8_t *gatt_client_reserve_request_buffer(gatt_client_t *gatt_client) {
254     l2cap_reserve_packet_buffer();
255     return l2cap_get_outgoing_buffer();
256 }
257 
258 // precondition: can_send_packet_now == TRUE
259 static uint8_t gatt_client_send(gatt_client_t * gatt_client, uint16_t len){
260 #ifdef ENABLE_GATT_OVER_CLASSIC
261     if (gatt_client->l2cap_psm){
262         return l2cap_send_prepared(gatt_client->l2cap_cid, len);
263     }
264 #endif
265     return l2cap_send_prepared_connectionless(gatt_client->con_handle, L2CAP_CID_ATTRIBUTE_PROTOCOL, len);
266 }
267 
268 // precondition: can_send_packet_now == TRUE
269 static uint8_t att_confirmation(gatt_client_t * gatt_client) {
270     uint8_t *request = gatt_client_reserve_request_buffer(gatt_client);
271 
272     request[0] = ATT_HANDLE_VALUE_CONFIRMATION;
273 
274     return gatt_client_send(gatt_client, 1);
275 }
276 
277 // precondition: can_send_packet_now == TRUE
278 static uint8_t att_find_information_request(gatt_client_t *gatt_client, uint8_t request_type, uint16_t start_handle,
279                                             uint16_t end_handle) {
280     uint8_t *request = gatt_client_reserve_request_buffer(gatt_client);
281 
282     request[0] = request_type;
283     little_endian_store_16(request, 1, start_handle);
284     little_endian_store_16(request, 3, end_handle);
285 
286     return gatt_client_send(gatt_client, 5);
287 }
288 
289 // precondition: can_send_packet_now == TRUE
290 static uint8_t
291 att_find_by_type_value_request(gatt_client_t *gatt_client, uint8_t request_type, uint16_t attribute_group_type,
292                                uint16_t start_handle, uint16_t end_handle, uint8_t *value, uint16_t value_size) {
293     uint8_t *request = gatt_client_reserve_request_buffer(gatt_client);
294     request[0] = request_type;
295 
296     little_endian_store_16(request, 1, start_handle);
297     little_endian_store_16(request, 3, end_handle);
298     little_endian_store_16(request, 5, attribute_group_type);
299     (void)memcpy(&request[7], value, value_size);
300 
301     return gatt_client_send(gatt_client, 7u + value_size);
302 }
303 
304 // precondition: can_send_packet_now == TRUE
305 static uint8_t
306 att_read_by_type_or_group_request_for_uuid16(gatt_client_t *gatt_client, uint8_t request_type, uint16_t uuid16,
307                                              uint16_t start_handle, uint16_t end_handle) {
308     uint8_t *request = gatt_client_reserve_request_buffer(gatt_client);
309 
310     request[0] = request_type;
311     little_endian_store_16(request, 1, start_handle);
312     little_endian_store_16(request, 3, end_handle);
313     little_endian_store_16(request, 5, uuid16);
314 
315     return gatt_client_send(gatt_client, 7);
316 }
317 
318 // precondition: can_send_packet_now == TRUE
319 static uint8_t
320 att_read_by_type_or_group_request_for_uuid128(gatt_client_t *gatt_client, uint8_t request_type, const uint8_t *uuid128,
321                                               uint16_t start_handle, uint16_t end_handle) {
322     uint8_t *request = gatt_client_reserve_request_buffer(gatt_client);
323 
324     request[0] = request_type;
325     little_endian_store_16(request, 1, start_handle);
326     little_endian_store_16(request, 3, end_handle);
327     reverse_128(uuid128, &request[5]);
328 
329     return gatt_client_send(gatt_client, 21);
330 }
331 
332 // precondition: can_send_packet_now == TRUE
333 static uint8_t att_read_request(gatt_client_t *gatt_client, uint8_t request_type, uint16_t attribute_handle) {
334     uint8_t *request = gatt_client_reserve_request_buffer(gatt_client);
335 
336     request[0] = request_type;
337     little_endian_store_16(request, 1, attribute_handle);
338 
339     return gatt_client_send(gatt_client, 3);
340 }
341 
342 // precondition: can_send_packet_now == TRUE
343 static uint8_t att_read_blob_request(gatt_client_t *gatt_client, uint8_t request_type, uint16_t attribute_handle,
344                                      uint16_t value_offset) {
345     uint8_t *request = gatt_client_reserve_request_buffer(gatt_client);
346 
347     request[0] = request_type;
348     little_endian_store_16(request, 1, attribute_handle);
349     little_endian_store_16(request, 3, value_offset);
350 
351     return gatt_client_send(gatt_client, 5);
352 }
353 
354 static uint8_t
355 att_read_multiple_request(gatt_client_t *gatt_client, uint16_t num_value_handles, uint16_t *value_handles) {
356     uint8_t *request = gatt_client_reserve_request_buffer(gatt_client);
357 
358     request[0] = ATT_READ_MULTIPLE_REQUEST;
359     uint16_t i;
360     uint16_t offset = 1;
361     for (i=0;i<num_value_handles;i++){
362         little_endian_store_16(request, offset, value_handles[i]);
363         offset += 2;
364     }
365 
366     return gatt_client_send(gatt_client, offset);
367 }
368 
369 #ifdef ENABLE_LE_SIGNED_WRITE
370 // precondition: can_send_packet_now == TRUE
371 static uint8_t att_signed_write_request(gatt_client_t *gatt_client, uint16_t request_type, uint16_t attribute_handle,
372                                         uint16_t value_length, uint8_t *value, uint32_t sign_counter, uint8_t sgn[8]) {
373     uint8_t *request = gatt_client_reserve_request_buffer(gatt_client);
374 
375     request[0] = request_type;
376     little_endian_store_16(request, 1, attribute_handle);
377     (void)memcpy(&request[3], value, value_length);
378     little_endian_store_32(request, 3 + value_length, sign_counter);
379     reverse_64(sgn, &request[3 + value_length + 4]);
380 
381     return gatt_client_send(gatt_client, 3 + value_length + 12);
382 }
383 #endif
384 
385 // precondition: can_send_packet_now == TRUE
386 static uint8_t
387 att_write_request(gatt_client_t *gatt_client, uint8_t request_type, uint16_t attribute_handle, uint16_t value_length,
388                   uint8_t *value) {
389     uint8_t *request = gatt_client_reserve_request_buffer(gatt_client);
390 
391     request[0] = request_type;
392     little_endian_store_16(request, 1, attribute_handle);
393     (void)memcpy(&request[3], value, value_length);
394 
395     return gatt_client_send(gatt_client, 3u + value_length);
396 }
397 
398 // precondition: can_send_packet_now == TRUE
399 static uint8_t att_execute_write_request(gatt_client_t *gatt_client, uint8_t request_type, uint8_t execute_write) {
400     uint8_t *request = gatt_client_reserve_request_buffer(gatt_client);
401 
402     request[0] = request_type;
403     request[1] = execute_write;
404 
405     return gatt_client_send(gatt_client, 2);
406 }
407 
408 // precondition: can_send_packet_now == TRUE
409 static uint8_t att_prepare_write_request(gatt_client_t *gatt_client, uint8_t request_type, uint16_t attribute_handle,
410                                          uint16_t value_offset, uint16_t blob_length, uint8_t *value) {
411     uint8_t *request = gatt_client_reserve_request_buffer(gatt_client);
412 
413     request[0] = request_type;
414     little_endian_store_16(request, 1, attribute_handle);
415     little_endian_store_16(request, 3, value_offset);
416     (void)memcpy(&request[5], &value[value_offset], blob_length);
417 
418     return gatt_client_send(gatt_client,  5u + blob_length);
419 }
420 
421 static uint8_t att_exchange_mtu_request(gatt_client_t *gatt_client) {
422     uint8_t *request = gatt_client_reserve_request_buffer(gatt_client);
423 
424     request[0] = ATT_EXCHANGE_MTU_REQUEST;
425     uint16_t mtu = l2cap_max_le_mtu();
426     little_endian_store_16(request, 1, mtu);
427 
428     return gatt_client_send(gatt_client, 3);
429 }
430 
431 static uint16_t write_blob_length(gatt_client_t * gatt_client){
432     uint16_t max_blob_length = gatt_client->mtu - 5u;
433     if (gatt_client->attribute_offset >= gatt_client->attribute_length) {
434         return 0;
435     }
436     uint16_t rest_length = gatt_client->attribute_length - gatt_client->attribute_offset;
437     if (max_blob_length > rest_length){
438         return rest_length;
439     }
440     return max_blob_length;
441 }
442 
443 static void send_gatt_services_request(gatt_client_t *gatt_client){
444     att_read_by_type_or_group_request_for_uuid16(gatt_client, ATT_READ_BY_GROUP_TYPE_REQUEST,
445                                                  gatt_client->uuid16, gatt_client->start_group_handle,
446                                                  gatt_client->end_group_handle);
447 }
448 
449 static void send_gatt_by_uuid_request(gatt_client_t *gatt_client, uint16_t attribute_group_type){
450     if (gatt_client->uuid16){
451         uint8_t uuid16[2];
452         little_endian_store_16(uuid16, 0, gatt_client->uuid16);
453         att_find_by_type_value_request(gatt_client, ATT_FIND_BY_TYPE_VALUE_REQUEST, attribute_group_type,
454                                        gatt_client->start_group_handle, gatt_client->end_group_handle, uuid16, 2);
455         return;
456     }
457     uint8_t uuid128[16];
458     reverse_128(gatt_client->uuid128, uuid128);
459     att_find_by_type_value_request(gatt_client, ATT_FIND_BY_TYPE_VALUE_REQUEST, attribute_group_type,
460                                    gatt_client->start_group_handle, gatt_client->end_group_handle, uuid128, 16);
461 }
462 
463 static void send_gatt_services_by_uuid_request(gatt_client_t *gatt_client){
464     send_gatt_by_uuid_request(gatt_client, GATT_PRIMARY_SERVICE_UUID);
465 }
466 
467 static void send_gatt_included_service_uuid_request(gatt_client_t *gatt_client){
468     att_read_request(gatt_client, ATT_READ_REQUEST, gatt_client->query_start_handle);
469 }
470 
471 static void send_gatt_included_service_request(gatt_client_t *gatt_client){
472     att_read_by_type_or_group_request_for_uuid16(gatt_client, ATT_READ_BY_TYPE_REQUEST,
473                                                  GATT_INCLUDE_SERVICE_UUID, gatt_client->start_group_handle,
474                                                  gatt_client->end_group_handle);
475 }
476 
477 static void send_gatt_characteristic_request(gatt_client_t *gatt_client){
478     att_read_by_type_or_group_request_for_uuid16(gatt_client, ATT_READ_BY_TYPE_REQUEST,
479                                                  GATT_CHARACTERISTICS_UUID, gatt_client->start_group_handle,
480                                                  gatt_client->end_group_handle);
481 }
482 
483 static void send_gatt_characteristic_descriptor_request(gatt_client_t *gatt_client){
484     att_find_information_request(gatt_client, ATT_FIND_INFORMATION_REQUEST, gatt_client->start_group_handle,
485                                  gatt_client->end_group_handle);
486 }
487 
488 static void send_gatt_read_characteristic_value_request(gatt_client_t *gatt_client){
489     att_read_request(gatt_client, ATT_READ_REQUEST, gatt_client->attribute_handle);
490 }
491 
492 static void send_gatt_read_by_type_request(gatt_client_t * gatt_client){
493     if (gatt_client->uuid16){
494         att_read_by_type_or_group_request_for_uuid16(gatt_client, ATT_READ_BY_TYPE_REQUEST,
495                                                      gatt_client->uuid16, gatt_client->start_group_handle,
496                                                      gatt_client->end_group_handle);
497     } else {
498         att_read_by_type_or_group_request_for_uuid128(gatt_client, ATT_READ_BY_TYPE_REQUEST,
499                                                       gatt_client->uuid128, gatt_client->start_group_handle,
500                                                       gatt_client->end_group_handle);
501     }
502 }
503 
504 static void send_gatt_read_blob_request(gatt_client_t *gatt_client){
505     if (gatt_client->attribute_offset == 0){
506         att_read_request(gatt_client, ATT_READ_REQUEST, gatt_client->attribute_handle);
507     } else {
508         att_read_blob_request(gatt_client, ATT_READ_BLOB_REQUEST, gatt_client->attribute_handle,
509                               gatt_client->attribute_offset);
510     }
511 }
512 
513 static void send_gatt_read_multiple_request(gatt_client_t * gatt_client){
514     att_read_multiple_request(gatt_client, gatt_client->read_multiple_handle_count, gatt_client->read_multiple_handles);
515 }
516 
517 static void send_gatt_write_attribute_value_request(gatt_client_t * gatt_client){
518     att_write_request(gatt_client, ATT_WRITE_REQUEST, gatt_client->attribute_handle, gatt_client->attribute_length,
519                       gatt_client->attribute_value);
520 }
521 
522 static void send_gatt_write_client_characteristic_configuration_request(gatt_client_t * gatt_client){
523     att_write_request(gatt_client, ATT_WRITE_REQUEST, gatt_client->client_characteristic_configuration_handle, 2,
524                       gatt_client->client_characteristic_configuration_value);
525 }
526 
527 static void send_gatt_prepare_write_request(gatt_client_t * gatt_client){
528     att_prepare_write_request(gatt_client, ATT_PREPARE_WRITE_REQUEST, gatt_client->attribute_handle,
529                               gatt_client->attribute_offset, write_blob_length(gatt_client),
530                               gatt_client->attribute_value);
531 }
532 
533 static void send_gatt_execute_write_request(gatt_client_t * gatt_client){
534     att_execute_write_request(gatt_client, ATT_EXECUTE_WRITE_REQUEST, 1);
535 }
536 
537 static void send_gatt_cancel_prepared_write_request(gatt_client_t * gatt_client){
538     att_execute_write_request(gatt_client, ATT_EXECUTE_WRITE_REQUEST, 0);
539 }
540 
541 #ifndef ENABLE_GATT_FIND_INFORMATION_FOR_CCC_DISCOVERY
542 static void send_gatt_read_client_characteristic_configuration_request(gatt_client_t * gatt_client){
543     att_read_by_type_or_group_request_for_uuid16(gatt_client, ATT_READ_BY_TYPE_REQUEST,
544                                                  GATT_CLIENT_CHARACTERISTICS_CONFIGURATION,
545                                                  gatt_client->start_group_handle, gatt_client->end_group_handle);
546 }
547 #endif
548 
549 static void send_gatt_read_characteristic_descriptor_request(gatt_client_t * gatt_client){
550     att_read_request(gatt_client, ATT_READ_REQUEST, gatt_client->attribute_handle);
551 }
552 
553 #ifdef ENABLE_LE_SIGNED_WRITE
554 static void send_gatt_signed_write_request(gatt_client_t * gatt_client, uint32_t sign_counter){
555     att_signed_write_request(gatt_client, ATT_SIGNED_WRITE_COMMAND, gatt_client->attribute_handle,
556                              gatt_client->attribute_length, gatt_client->attribute_value, sign_counter,
557                              gatt_client->cmac);
558 }
559 #endif
560 
561 static uint16_t get_last_result_handle_from_service_list(uint8_t * packet, uint16_t size){
562     if (size < 2) return 0xffff;
563     uint8_t attr_length = packet[1];
564     if ((2 + attr_length) > size) return 0xffff;
565     return little_endian_read_16(packet, size - attr_length + 2u);
566 }
567 
568 static uint16_t get_last_result_handle_from_characteristics_list(uint8_t * packet, uint16_t size){
569     if (size < 2) return 0xffff;
570     uint8_t attr_length = packet[1];
571     if ((2 + attr_length) > size) return 0xffff;
572     return little_endian_read_16(packet, size - attr_length + 3u);
573 }
574 
575 static uint16_t get_last_result_handle_from_included_services_list(uint8_t * packet, uint16_t size){
576     if (size < 2) return 0xffff;
577     uint8_t attr_length = packet[1];
578     if ((2 + attr_length) > size) return 0xffff;
579     return little_endian_read_16(packet, size - attr_length);
580 }
581 
582 static void gatt_client_notify_can_send_query(gatt_client_t * gatt_client){
583     while (gatt_client->gatt_client_state == P_READY){
584         btstack_context_callback_registration_t * callback = (btstack_context_callback_registration_t *) btstack_linked_list_pop(&gatt_client->query_requests);
585         if (callback == NULL) {
586             return;
587         }
588         (*callback->callback)(callback->context);
589     }
590 }
591 
592 static void gatt_client_handle_transaction_complete(gatt_client_t * gatt_client){
593     gatt_client->gatt_client_state = P_READY;
594     gatt_client_timeout_stop(gatt_client);
595     gatt_client_notify_can_send_query(gatt_client);
596 }
597 
598 static void emit_event_new(btstack_packet_handler_t callback, uint8_t * packet, uint16_t size){
599     if (!callback) return;
600     hci_dump_packet(HCI_EVENT_PACKET, 1, packet, size);
601     (*callback)(HCI_EVENT_PACKET, 0, packet, size);
602 }
603 
604 void gatt_client_listen_for_characteristic_value_updates(gatt_client_notification_t * notification, btstack_packet_handler_t callback, hci_con_handle_t con_handle, gatt_client_characteristic_t * characteristic){
605     notification->callback = callback;
606     notification->con_handle = con_handle;
607     if (characteristic == NULL){
608         notification->attribute_handle = GATT_CLIENT_ANY_VALUE_HANDLE;
609     } else {
610         notification->attribute_handle = characteristic->value_handle;
611     }
612     btstack_linked_list_add(&gatt_client_value_listeners, (btstack_linked_item_t*) notification);
613 }
614 
615 void gatt_client_stop_listening_for_characteristic_value_updates(gatt_client_notification_t * notification){
616     btstack_linked_list_remove(&gatt_client_value_listeners, (btstack_linked_item_t*) notification);
617 }
618 
619 static void emit_event_to_registered_listeners(hci_con_handle_t con_handle, uint16_t attribute_handle, uint8_t * packet, uint16_t size){
620     btstack_linked_list_iterator_t it;
621     btstack_linked_list_iterator_init(&it, &gatt_client_value_listeners);
622     while (btstack_linked_list_iterator_has_next(&it)){
623         gatt_client_notification_t * notification = (gatt_client_notification_t*) btstack_linked_list_iterator_next(&it);
624         if ((notification->con_handle       != GATT_CLIENT_ANY_CONNECTION)   && (notification->con_handle       != con_handle)) continue;
625         if ((notification->attribute_handle != GATT_CLIENT_ANY_VALUE_HANDLE) && (notification->attribute_handle != attribute_handle)) continue;
626         (*notification->callback)(HCI_EVENT_PACKET, 0, packet, size);
627     }
628 }
629 
630 static void emit_gatt_complete_event(gatt_client_t * gatt_client, uint8_t att_status){
631     // @format H1
632     uint8_t packet[5];
633     packet[0] = GATT_EVENT_QUERY_COMPLETE;
634     packet[1] = 3;
635     little_endian_store_16(packet, 2, gatt_client->con_handle);
636     packet[4] = att_status;
637     emit_event_new(gatt_client->callback, packet, sizeof(packet));
638 }
639 
640 static void emit_gatt_service_query_result_event(gatt_client_t * gatt_client, uint16_t start_group_handle, uint16_t end_group_handle, const uint8_t * uuid128){
641     // @format HX
642     uint8_t packet[24];
643     packet[0] = GATT_EVENT_SERVICE_QUERY_RESULT;
644     packet[1] = sizeof(packet) - 2u;
645     little_endian_store_16(packet, 2, gatt_client->con_handle);
646     ///
647     little_endian_store_16(packet, 4, start_group_handle);
648     little_endian_store_16(packet, 6, end_group_handle);
649     reverse_128(uuid128, &packet[8]);
650     emit_event_new(gatt_client->callback, packet, sizeof(packet));
651 }
652 
653 static void emit_gatt_included_service_query_result_event(gatt_client_t * gatt_client, uint16_t include_handle, uint16_t start_group_handle, uint16_t end_group_handle, const uint8_t * uuid128){
654     // @format HX
655     uint8_t packet[26];
656     packet[0] = GATT_EVENT_INCLUDED_SERVICE_QUERY_RESULT;
657     packet[1] = sizeof(packet) - 2u;
658     little_endian_store_16(packet, 2, gatt_client->con_handle);
659     ///
660     little_endian_store_16(packet, 4, include_handle);
661     //
662     little_endian_store_16(packet, 6, start_group_handle);
663     little_endian_store_16(packet, 8, end_group_handle);
664     reverse_128(uuid128, &packet[10]);
665     emit_event_new(gatt_client->callback, packet, sizeof(packet));
666 }
667 
668 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,
669                                                         uint16_t properties, const uint8_t * uuid128){
670     // @format HY
671     uint8_t packet[28];
672     packet[0] = GATT_EVENT_CHARACTERISTIC_QUERY_RESULT;
673     packet[1] = sizeof(packet) - 2u;
674     little_endian_store_16(packet, 2, gatt_client->con_handle);
675     ///
676     little_endian_store_16(packet, 4,  start_handle);
677     little_endian_store_16(packet, 6,  value_handle);
678     little_endian_store_16(packet, 8,  end_handle);
679     little_endian_store_16(packet, 10, properties);
680     reverse_128(uuid128, &packet[12]);
681     emit_event_new(gatt_client->callback, packet, sizeof(packet));
682 }
683 
684 static void emit_gatt_all_characteristic_descriptors_result_event(
685         gatt_client_t * gatt_client, uint16_t descriptor_handle, const uint8_t * uuid128){
686     // @format HZ
687     uint8_t packet[22];
688     packet[0] = GATT_EVENT_ALL_CHARACTERISTIC_DESCRIPTORS_QUERY_RESULT;
689     packet[1] = sizeof(packet) - 2u;
690     little_endian_store_16(packet, 2, gatt_client->con_handle);
691     ///
692     little_endian_store_16(packet, 4,  descriptor_handle);
693     reverse_128(uuid128, &packet[6]);
694     emit_event_new(gatt_client->callback, packet, sizeof(packet));
695 }
696 
697 static void emit_gatt_mtu_exchanged_result_event(gatt_client_t * gatt_client, uint16_t new_mtu){
698     // @format H2
699     uint8_t packet[6];
700     packet[0] = GATT_EVENT_MTU;
701     packet[1] = sizeof(packet) - 2u;
702     little_endian_store_16(packet, 2, gatt_client->con_handle);
703     little_endian_store_16(packet, 4, new_mtu);
704     att_dispatch_client_mtu_exchanged(gatt_client->con_handle, new_mtu);
705     emit_event_new(gatt_client->callback, packet, sizeof(packet));
706 }
707 ///
708 static void report_gatt_services(gatt_client_t * gatt_client, uint8_t * packet, uint16_t size){
709     if (size < 2) return;
710     uint8_t attr_length = packet[1];
711     uint8_t uuid_length = attr_length - 4u;
712 
713     int i;
714     for (i = 2; (i+attr_length) <= size; i += attr_length){
715         uint16_t start_group_handle = little_endian_read_16(packet,i);
716         uint16_t end_group_handle   = little_endian_read_16(packet,i+2);
717         uint8_t  uuid128[16];
718         uint16_t uuid16 = 0;
719 
720         if (uuid_length == 2u){
721             uuid16 = little_endian_read_16(packet, i+4);
722             uuid_add_bluetooth_prefix((uint8_t*) &uuid128, uuid16);
723         } else if (uuid_length == 16u) {
724             reverse_128(&packet[i+4], uuid128);
725         } else {
726             return;
727         }
728         emit_gatt_service_query_result_event(gatt_client, start_group_handle, end_group_handle, uuid128);
729     }
730 }
731 
732 // helper
733 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){
734     uint8_t uuid128[16];
735     uint16_t uuid16 = 0;
736     if (uuid_length == 2u){
737         uuid16 = little_endian_read_16(uuid, 0);
738         uuid_add_bluetooth_prefix((uint8_t*) uuid128, uuid16);
739     } else if (uuid_length == 16u){
740         reverse_128(uuid, uuid128);
741     } else {
742         return;
743     }
744 
745     if (gatt_client->filter_with_uuid && (memcmp(gatt_client->uuid128, uuid128, 16) != 0)) return;
746 
747     gatt_client->characteristic_properties = properties;
748     gatt_client->characteristic_start_handle = start_handle;
749     gatt_client->attribute_handle = value_handle;
750 
751     if (gatt_client->filter_with_uuid) return;
752 
753     gatt_client->uuid16 = uuid16;
754     (void)memcpy(gatt_client->uuid128, uuid128, 16);
755 }
756 
757 static void characteristic_end_found(gatt_client_t * gatt_client, uint16_t end_handle){
758     // TODO: stop searching if filter and uuid found
759 
760     if (!gatt_client->characteristic_start_handle) return;
761 
762     emit_gatt_characteristic_query_result_event(gatt_client, gatt_client->characteristic_start_handle, gatt_client->attribute_handle,
763                                                 end_handle, gatt_client->characteristic_properties, gatt_client->uuid128);
764 
765     gatt_client->characteristic_start_handle = 0;
766 }
767 
768 static void report_gatt_characteristics(gatt_client_t * gatt_client, uint8_t * packet, uint16_t size){
769     if (size < 2u) return;
770     uint8_t attr_length = packet[1];
771     if ((attr_length != 7u) && (attr_length != 21u)) return;
772     uint8_t uuid_length = attr_length - 5u;
773     int i;
774     for (i = 2u; (i + attr_length) <= size; i += attr_length){
775         uint16_t start_handle = little_endian_read_16(packet, i);
776         uint8_t  properties = packet[i+2];
777         uint16_t value_handle = little_endian_read_16(packet, i+3);
778         characteristic_end_found(gatt_client, start_handle - 1u);
779         characteristic_start_found(gatt_client, start_handle, properties, value_handle, &packet[i + 5], uuid_length);
780     }
781 }
782 
783 static void report_gatt_included_service_uuid16(gatt_client_t * gatt_client, uint16_t include_handle, uint16_t uuid16){
784     uint8_t normalized_uuid128[16];
785     uuid_add_bluetooth_prefix(normalized_uuid128, uuid16);
786     emit_gatt_included_service_query_result_event(gatt_client, include_handle, gatt_client->query_start_handle,
787                                                   gatt_client->query_end_handle, normalized_uuid128);
788 }
789 
790 static void report_gatt_included_service_uuid128(gatt_client_t * gatt_client, uint16_t include_handle, const uint8_t * uuid128){
791     emit_gatt_included_service_query_result_event(gatt_client, include_handle, gatt_client->query_start_handle,
792                                                   gatt_client->query_end_handle, uuid128);
793 }
794 
795 // @return packet pointer
796 // @note assume that value is part of an l2cap buffer - overwrite HCI + L2CAP packet headers
797 static const int characteristic_value_event_header_size = 8;
798 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){
799 #ifdef FUZZING_BUILD_MODE_UNSAFE_FOR_PRODUCTION
800     // copy value into test packet for testing
801     static uint8_t packet[1000];
802     memcpy(&packet[8], value, length);
803 #else
804     // before the value inside the ATT PDU
805     uint8_t * packet = value - characteristic_value_event_header_size;
806 #endif
807     packet[0] = type;
808     packet[1] = characteristic_value_event_header_size - 2 + length;
809     little_endian_store_16(packet, 2, con_handle);
810     little_endian_store_16(packet, 4, attribute_handle);
811     little_endian_store_16(packet, 6, length);
812     return packet;
813 }
814 
815 // @return packet pointer
816 // @note assume that value is part of an l2cap buffer - overwrite parts of the HCI/L2CAP/ATT packet (4/4/3) bytes
817 static const int long_characteristic_value_event_header_size = 10;
818 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){
819 #ifdef FUZZING_BUILD_MODE_UNSAFE_FOR_PRODUCTION
820     // avoid using pre ATT headers.
821     return NULL;
822 #endif
823 #if defined(HCI_INCOMING_PRE_BUFFER_SIZE) && (HCI_INCOMING_PRE_BUFFER_SIZE >= 10 - 8) // L2CAP Header (4) - ACL Header (4)
824     // before the value inside the ATT PDU
825     uint8_t * packet = value - long_characteristic_value_event_header_size;
826     packet[0] = type;
827     packet[1] = long_characteristic_value_event_header_size - 2 + length;
828     little_endian_store_16(packet, 2, con_handle);
829     little_endian_store_16(packet, 4, attribute_handle);
830     little_endian_store_16(packet, 6, offset);
831     little_endian_store_16(packet, 8, length);
832     return packet;
833 #else
834     log_error("HCI_INCOMING_PRE_BUFFER_SIZE >= 2 required for long characteristic reads");
835     return NULL;
836 #endif
837 }
838 
839 // test if notification/indication should be delivered to application (BLESA)
840 static bool gatt_client_accept_server_message(gatt_client_t *gatt_client) {
841 #ifdef ENABLE_LE_PROACTIVE_AUTHENTICATION
842 	// ignore messages until re-encryption is complete
843     if (gap_reconnect_security_setup_active(gatt_client->con_handle)) return false;
844 
845 	// after that ignore if bonded but not encrypted
846 	return !gap_bonded(gatt_client->con_handle) || (gap_encryption_key_size(gatt_client->con_handle) > 0);
847 #else
848     UNUSED(gatt_client);
849 	return true;
850 #endif
851 }
852 
853 
854 // @note assume that value is part of an l2cap buffer - overwrite parts of the HCI/L2CAP/ATT packet (4/4/3) bytes
855 static void report_gatt_notification(gatt_client_t *gatt_client, uint16_t value_handle, uint8_t *value, int length) {
856 	if (!gatt_client_accept_server_message(gatt_client)) return;
857     uint8_t * packet = setup_characteristic_value_packet(GATT_EVENT_NOTIFICATION, gatt_client->con_handle, value_handle, value, length);
858     emit_event_to_registered_listeners(gatt_client->con_handle, value_handle, packet, characteristic_value_event_header_size + length);
859 }
860 
861 // @note assume that value is part of an l2cap buffer - overwrite parts of the HCI/L2CAP/ATT packet (4/4/3) bytes
862 static void report_gatt_indication(gatt_client_t *gatt_client, uint16_t value_handle, uint8_t *value, int length) {
863 	if (!gatt_client_accept_server_message(gatt_client)) return;
864     uint8_t * packet = setup_characteristic_value_packet(GATT_EVENT_INDICATION, gatt_client->con_handle, value_handle, value, length);
865     emit_event_to_registered_listeners(gatt_client->con_handle, value_handle, packet, characteristic_value_event_header_size + length);
866 }
867 
868 // @note assume that value is part of an l2cap buffer - overwrite parts of the HCI/L2CAP/ATT packet (4/4/3) bytes
869 static void report_gatt_characteristic_value(gatt_client_t * gatt_client, uint16_t attribute_handle, uint8_t * value, uint16_t length){
870     uint8_t * packet = setup_characteristic_value_packet(GATT_EVENT_CHARACTERISTIC_VALUE_QUERY_RESULT, gatt_client->con_handle, attribute_handle, value, length);
871     emit_event_new(gatt_client->callback, packet, characteristic_value_event_header_size + length);
872 }
873 
874 // @note assume that value is part of an l2cap buffer - overwrite parts of the HCI/L2CAP/ATT packet (4/4/3) bytes
875 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){
876     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);
877     if (!packet) return;
878     emit_event_new(gatt_client->callback, packet, blob_length + long_characteristic_value_event_header_size);
879 }
880 
881 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){
882     UNUSED(value_offset);
883     uint8_t * packet = setup_characteristic_value_packet(GATT_EVENT_CHARACTERISTIC_DESCRIPTOR_QUERY_RESULT, gatt_client->con_handle, descriptor_handle, value, value_length);
884     emit_event_new(gatt_client->callback, packet, value_length + 8u);
885 }
886 
887 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){
888     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);
889     if (!packet) return;
890     emit_event_new(gatt_client->callback, packet, blob_length + long_characteristic_value_event_header_size);
891 }
892 
893 static void report_gatt_all_characteristic_descriptors(gatt_client_t * gatt_client, uint8_t * packet, uint16_t size, uint16_t pair_size){
894     int i;
895     for (i = 0u; (i + pair_size) <= size; i += pair_size){
896         uint16_t descriptor_handle = little_endian_read_16(packet,i);
897         uint8_t uuid128[16];
898         uint16_t uuid16 = 0;
899         if (pair_size == 4u){
900             uuid16 = little_endian_read_16(packet,i+2);
901             uuid_add_bluetooth_prefix(uuid128, uuid16);
902         } else {
903             reverse_128(&packet[i+2], uuid128);
904         }
905         emit_gatt_all_characteristic_descriptors_result_event(gatt_client, descriptor_handle, uuid128);
906     }
907 
908 }
909 
910 static int is_query_done(gatt_client_t * gatt_client, uint16_t last_result_handle){
911     return last_result_handle >= gatt_client->end_group_handle;
912 }
913 
914 static void trigger_next_query(gatt_client_t * gatt_client, uint16_t last_result_handle, gatt_client_state_t next_query_state){
915     if (is_query_done(gatt_client, last_result_handle)){
916         gatt_client_handle_transaction_complete(gatt_client);
917         emit_gatt_complete_event(gatt_client, ATT_ERROR_SUCCESS);
918         return;
919     }
920     // next
921     gatt_client->start_group_handle = last_result_handle + 1u;
922     gatt_client->gatt_client_state = next_query_state;
923 }
924 
925 static void trigger_next_included_service_query(gatt_client_t * gatt_client, uint16_t last_result_handle){
926     trigger_next_query(gatt_client, last_result_handle, P_W2_SEND_INCLUDED_SERVICE_QUERY);
927 }
928 
929 static void trigger_next_service_query(gatt_client_t * gatt_client, uint16_t last_result_handle){
930     trigger_next_query(gatt_client, last_result_handle, P_W2_SEND_SERVICE_QUERY);
931 }
932 
933 static void trigger_next_service_by_uuid_query(gatt_client_t * gatt_client, uint16_t last_result_handle){
934     trigger_next_query(gatt_client, last_result_handle, P_W2_SEND_SERVICE_WITH_UUID_QUERY);
935 }
936 
937 static void trigger_next_characteristic_query(gatt_client_t * gatt_client, uint16_t last_result_handle){
938     if (is_query_done(gatt_client, last_result_handle)){
939         // report last characteristic
940         characteristic_end_found(gatt_client, gatt_client->end_group_handle);
941     }
942     trigger_next_query(gatt_client, last_result_handle, P_W2_SEND_ALL_CHARACTERISTICS_OF_SERVICE_QUERY);
943 }
944 
945 static void trigger_next_characteristic_descriptor_query(gatt_client_t * gatt_client, uint16_t last_result_handle){
946     trigger_next_query(gatt_client, last_result_handle, P_W2_SEND_ALL_CHARACTERISTIC_DESCRIPTORS_QUERY);
947 }
948 
949 static void trigger_next_read_by_type_query(gatt_client_t * gatt_client, uint16_t last_result_handle){
950     trigger_next_query(gatt_client, last_result_handle, P_W2_SEND_READ_BY_TYPE_REQUEST);
951 }
952 
953 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){
954     gatt_client->attribute_offset += write_blob_length(gatt_client);
955     uint16_t next_blob_length =  write_blob_length(gatt_client);
956 
957     if (next_blob_length == 0u){
958         gatt_client->gatt_client_state = done_state;
959         return;
960     }
961     gatt_client->gatt_client_state = next_query_state;
962 }
963 
964 static void trigger_next_blob_query(gatt_client_t * gatt_client, gatt_client_state_t next_query_state, uint16_t received_blob_length){
965 
966     uint16_t max_blob_length = gatt_client->mtu - 1u;
967     if (received_blob_length < max_blob_length){
968         gatt_client_handle_transaction_complete(gatt_client);
969         emit_gatt_complete_event(gatt_client, ATT_ERROR_SUCCESS);
970         return;
971     }
972 
973     gatt_client->attribute_offset += received_blob_length;
974     gatt_client->gatt_client_state = next_query_state;
975 }
976 
977 
978 static int is_value_valid(gatt_client_t *gatt_client, uint8_t *packet, uint16_t size){
979     uint16_t attribute_handle = little_endian_read_16(packet, 1);
980     uint16_t value_offset = little_endian_read_16(packet, 3);
981 
982     if (gatt_client->attribute_handle != attribute_handle) return 0;
983     if (gatt_client->attribute_offset != value_offset) return 0;
984     return memcmp(&gatt_client->attribute_value[gatt_client->attribute_offset], &packet[5], size - 5u) == 0u;
985 }
986 
987 #ifdef ENABLE_LE_SIGNED_WRITE
988 static void gatt_client_run_for_client_start_signed_write(gatt_client_t *gatt_client) {
989     sm_key_t csrk;
990     le_device_db_local_csrk_get(gatt_client->le_device_index, csrk);
991     uint32_t sign_counter = le_device_db_local_counter_get(gatt_client->le_device_index);
992     gatt_client->gatt_client_state = P_W4_CMAC_RESULT;
993     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);
994 }
995 #endif
996 
997 // returns true if packet was sent
998 static bool gatt_client_run_for_gatt_client(gatt_client_t * gatt_client){
999 
1000     // wait until re-encryption is complete
1001     if (gap_reconnect_security_setup_active(gatt_client->con_handle)) return false;
1002 
1003     // wait until re-encryption is complete
1004     if (gatt_client->reencryption_active) return false;
1005 
1006     // wait until pairing complete (either reactive authentication or due to required security level)
1007     if (gatt_client->wait_for_authentication_complete) return false;
1008 
1009     bool client_request_pending = gatt_client->gatt_client_state != P_READY;
1010 
1011     // verify security level for Mandatory Authentication over LE
1012     bool check_security = true;
1013 #ifdef ENABLE_GATT_OVER_CLASSIC
1014     if (gatt_client->l2cap_psm != 0){
1015         check_security = false;
1016     }
1017 #endif
1018     if (client_request_pending && (gatt_client_required_security_level > gatt_client->security_level) && check_security){
1019         log_info("Trigger pairing, current security level %u, required %u\n", gatt_client->security_level, gatt_client_required_security_level);
1020         gatt_client->wait_for_authentication_complete = 1;
1021         // set att error code for pairing failure based on required level
1022         switch (gatt_client_required_security_level){
1023             case LEVEL_4:
1024             case LEVEL_3:
1025                 gatt_client->pending_error_code = ATT_ERROR_INSUFFICIENT_AUTHENTICATION;
1026                 break;
1027             default:
1028                 gatt_client->pending_error_code = ATT_ERROR_INSUFFICIENT_ENCRYPTION;
1029                 break;
1030         }
1031         sm_request_pairing(gatt_client->con_handle);
1032         // sm probably just sent a pdu
1033         return true;
1034     }
1035 
1036     switch (gatt_client->mtu_state) {
1037         case SEND_MTU_EXCHANGE:
1038             gatt_client->mtu_state = SENT_MTU_EXCHANGE;
1039             att_exchange_mtu_request(gatt_client);
1040             return true;
1041         case SENT_MTU_EXCHANGE:
1042             return false;
1043         default:
1044             break;
1045     }
1046 
1047     if (gatt_client->send_confirmation){
1048         gatt_client->send_confirmation = 0;
1049         att_confirmation(gatt_client);
1050         return true;
1051     }
1052 
1053     // check MTU for writes
1054     switch (gatt_client->gatt_client_state){
1055         case P_W2_SEND_WRITE_CHARACTERISTIC_VALUE:
1056         case P_W2_SEND_WRITE_CHARACTERISTIC_DESCRIPTOR:
1057             if (gatt_client->attribute_length <= (gatt_client->mtu - 3u)) break;
1058             log_error("gatt_client_run: value len %u > MTU %u - 3\n", gatt_client->attribute_length,gatt_client->mtu);
1059             gatt_client_handle_transaction_complete(gatt_client);
1060             emit_gatt_complete_event(gatt_client, ATT_ERROR_INVALID_ATTRIBUTE_VALUE_LENGTH);
1061             return false;
1062         default:
1063             break;
1064     }
1065 
1066     bool packet_sent = true;
1067     bool done = true;
1068     switch (gatt_client->gatt_client_state){
1069         case P_W2_SEND_SERVICE_QUERY:
1070             gatt_client->gatt_client_state = P_W4_SERVICE_QUERY_RESULT;
1071             send_gatt_services_request(gatt_client);
1072             break;
1073 
1074         case P_W2_SEND_SERVICE_WITH_UUID_QUERY:
1075             gatt_client->gatt_client_state = P_W4_SERVICE_WITH_UUID_RESULT;
1076             send_gatt_services_by_uuid_request(gatt_client);
1077             break;
1078 
1079         case P_W2_SEND_ALL_CHARACTERISTICS_OF_SERVICE_QUERY:
1080             gatt_client->gatt_client_state = P_W4_ALL_CHARACTERISTICS_OF_SERVICE_QUERY_RESULT;
1081             send_gatt_characteristic_request(gatt_client);
1082             break;
1083 
1084         case P_W2_SEND_CHARACTERISTIC_WITH_UUID_QUERY:
1085             gatt_client->gatt_client_state = P_W4_CHARACTERISTIC_WITH_UUID_QUERY_RESULT;
1086             send_gatt_characteristic_request(gatt_client);
1087             break;
1088 
1089         case P_W2_SEND_ALL_CHARACTERISTIC_DESCRIPTORS_QUERY:
1090             gatt_client->gatt_client_state = P_W4_CHARACTERISTIC_WITH_UUID_QUERY_RESULT;
1091             send_gatt_characteristic_descriptor_request(gatt_client);
1092             break;
1093 
1094         case P_W2_SEND_INCLUDED_SERVICE_QUERY:
1095             gatt_client->gatt_client_state = P_W4_INCLUDED_SERVICE_QUERY_RESULT;
1096             send_gatt_included_service_request(gatt_client);
1097             break;
1098 
1099         case P_W2_SEND_INCLUDED_SERVICE_WITH_UUID_QUERY:
1100             gatt_client->gatt_client_state = P_W4_INCLUDED_SERVICE_UUID_WITH_QUERY_RESULT;
1101             send_gatt_included_service_uuid_request(gatt_client);
1102             break;
1103 
1104         case P_W2_SEND_READ_CHARACTERISTIC_VALUE_QUERY:
1105             gatt_client->gatt_client_state = P_W4_READ_CHARACTERISTIC_VALUE_RESULT;
1106             send_gatt_read_characteristic_value_request(gatt_client);
1107             break;
1108 
1109         case P_W2_SEND_READ_BLOB_QUERY:
1110             gatt_client->gatt_client_state = P_W4_READ_BLOB_RESULT;
1111             send_gatt_read_blob_request(gatt_client);
1112             break;
1113 
1114         case P_W2_SEND_READ_BY_TYPE_REQUEST:
1115             gatt_client->gatt_client_state = P_W4_READ_BY_TYPE_RESPONSE;
1116             send_gatt_read_by_type_request(gatt_client);
1117             break;
1118 
1119         case P_W2_SEND_READ_MULTIPLE_REQUEST:
1120             gatt_client->gatt_client_state = P_W4_READ_MULTIPLE_RESPONSE;
1121             send_gatt_read_multiple_request(gatt_client);
1122             break;
1123 
1124         case P_W2_SEND_WRITE_CHARACTERISTIC_VALUE:
1125             gatt_client->gatt_client_state = P_W4_WRITE_CHARACTERISTIC_VALUE_RESULT;
1126             send_gatt_write_attribute_value_request(gatt_client);
1127             break;
1128 
1129         case P_W2_PREPARE_WRITE:
1130             gatt_client->gatt_client_state = P_W4_PREPARE_WRITE_RESULT;
1131             send_gatt_prepare_write_request(gatt_client);
1132             break;
1133 
1134         case P_W2_PREPARE_WRITE_SINGLE:
1135             gatt_client->gatt_client_state = P_W4_PREPARE_WRITE_SINGLE_RESULT;
1136             send_gatt_prepare_write_request(gatt_client);
1137             break;
1138 
1139         case P_W2_PREPARE_RELIABLE_WRITE:
1140             gatt_client->gatt_client_state = P_W4_PREPARE_RELIABLE_WRITE_RESULT;
1141             send_gatt_prepare_write_request(gatt_client);
1142             break;
1143 
1144         case P_W2_EXECUTE_PREPARED_WRITE:
1145             gatt_client->gatt_client_state = P_W4_EXECUTE_PREPARED_WRITE_RESULT;
1146             send_gatt_execute_write_request(gatt_client);
1147             break;
1148 
1149         case P_W2_CANCEL_PREPARED_WRITE:
1150             gatt_client->gatt_client_state = P_W4_CANCEL_PREPARED_WRITE_RESULT;
1151             send_gatt_cancel_prepared_write_request(gatt_client);
1152             break;
1153 
1154         case P_W2_CANCEL_PREPARED_WRITE_DATA_MISMATCH:
1155             gatt_client->gatt_client_state = P_W4_CANCEL_PREPARED_WRITE_DATA_MISMATCH_RESULT;
1156             send_gatt_cancel_prepared_write_request(gatt_client);
1157             break;
1158 
1159 #ifdef ENABLE_GATT_FIND_INFORMATION_FOR_CCC_DISCOVERY
1160         case P_W2_SEND_FIND_CLIENT_CHARACTERISTIC_CONFIGURATION_QUERY:
1161             // use Find Information
1162             gatt_client->gatt_client_state = P_W4_FIND_CLIENT_CHARACTERISTIC_CONFIGURATION_QUERY_RESULT;
1163             send_gatt_characteristic_descriptor_request(gatt_client);
1164 #else
1165         case P_W2_SEND_READ_CLIENT_CHARACTERISTIC_CONFIGURATION_QUERY:
1166             // Use Read By Type
1167             gatt_client->gatt_client_state = P_W4_READ_CLIENT_CHARACTERISTIC_CONFIGURATION_QUERY_RESULT;
1168             send_gatt_read_client_characteristic_configuration_request(gatt_client);
1169 #endif
1170             break;
1171 
1172         case P_W2_SEND_READ_CHARACTERISTIC_DESCRIPTOR_QUERY:
1173             gatt_client->gatt_client_state = P_W4_READ_CHARACTERISTIC_DESCRIPTOR_RESULT;
1174             send_gatt_read_characteristic_descriptor_request(gatt_client);
1175             break;
1176 
1177         case P_W2_SEND_READ_BLOB_CHARACTERISTIC_DESCRIPTOR_QUERY:
1178             gatt_client->gatt_client_state = P_W4_READ_BLOB_CHARACTERISTIC_DESCRIPTOR_RESULT;
1179             send_gatt_read_blob_request(gatt_client);
1180             break;
1181 
1182         case P_W2_SEND_WRITE_CHARACTERISTIC_DESCRIPTOR:
1183             gatt_client->gatt_client_state = P_W4_WRITE_CHARACTERISTIC_DESCRIPTOR_RESULT;
1184             send_gatt_write_attribute_value_request(gatt_client);
1185             break;
1186 
1187         case P_W2_WRITE_CLIENT_CHARACTERISTIC_CONFIGURATION:
1188             gatt_client->gatt_client_state = P_W4_CLIENT_CHARACTERISTIC_CONFIGURATION_RESULT;
1189             send_gatt_write_client_characteristic_configuration_request(gatt_client);
1190             break;
1191 
1192         case P_W2_PREPARE_WRITE_CHARACTERISTIC_DESCRIPTOR:
1193             gatt_client->gatt_client_state = P_W4_PREPARE_WRITE_CHARACTERISTIC_DESCRIPTOR_RESULT;
1194             send_gatt_prepare_write_request(gatt_client);
1195             break;
1196 
1197         case P_W2_EXECUTE_PREPARED_WRITE_CHARACTERISTIC_DESCRIPTOR:
1198             gatt_client->gatt_client_state = P_W4_EXECUTE_PREPARED_WRITE_CHARACTERISTIC_DESCRIPTOR_RESULT;
1199             send_gatt_execute_write_request(gatt_client);
1200             break;
1201 
1202 #ifdef ENABLE_LE_SIGNED_WRITE
1203         case P_W4_IDENTITY_RESOLVING:
1204             log_info("P_W4_IDENTITY_RESOLVING - state %x", sm_identity_resolving_state(gatt_client->con_handle));
1205             switch (sm_identity_resolving_state(gatt_client->con_handle)){
1206                 case IRK_LOOKUP_SUCCEEDED:
1207                     gatt_client->le_device_index = sm_le_device_index(gatt_client->con_handle);
1208                     gatt_client->gatt_client_state = P_W4_CMAC_READY;
1209                     if (sm_cmac_ready()){
1210                         gatt_client_run_for_client_start_signed_write(gatt_client);
1211                     }
1212                     break;
1213                 case IRK_LOOKUP_FAILED:
1214                     gatt_client_handle_transaction_complete(gatt_client);
1215                     emit_gatt_complete_event(gatt_client, ATT_ERROR_BONDING_INFORMATION_MISSING);
1216                     break;
1217                 default:
1218                     break;
1219             }
1220             packet_sent = false;
1221             break;
1222 
1223         case P_W4_CMAC_READY:
1224             if (sm_cmac_ready()){
1225                 gatt_client_run_for_client_start_signed_write(gatt_client);
1226             }
1227             packet_sent = false;
1228             break;
1229 
1230         case P_W2_SEND_SIGNED_WRITE: {
1231             gatt_client->gatt_client_state = P_W4_SEND_SINGED_WRITE_DONE;
1232             // bump local signing counter
1233             uint32_t sign_counter = le_device_db_local_counter_get(gatt_client->le_device_index);
1234             le_device_db_local_counter_set(gatt_client->le_device_index, sign_counter + 1);
1235             // send signed write command
1236             send_gatt_signed_write_request(gatt_client, sign_counter);
1237             // finally, notifiy client that write is complete
1238             gatt_client_handle_transaction_complete(gatt_client);
1239             emit_gatt_complete_event(gatt_client, ATT_ERROR_SUCCESS);
1240             break;
1241         }
1242 #endif
1243         default:
1244             done = false;
1245             break;
1246     }
1247 
1248     if (done){
1249         return packet_sent;
1250     }
1251 
1252     // write without response callback
1253     btstack_context_callback_registration_t * callback =
1254             (btstack_context_callback_registration_t *) btstack_linked_list_pop(&gatt_client->write_without_response_requests);
1255     if (callback != NULL){
1256         (*callback->callback)(callback->context);
1257         return true;
1258     }
1259 
1260     // requested can send now old
1261     if (gatt_client->write_without_response_callback){
1262         btstack_packet_handler_t packet_handler = gatt_client->write_without_response_callback;
1263         gatt_client->write_without_response_callback = NULL;
1264         uint8_t event[4];
1265         event[0] = GATT_EVENT_CAN_WRITE_WITHOUT_RESPONSE;
1266         event[1] = sizeof(event) - 2u;
1267         little_endian_store_16(event, 2, gatt_client->con_handle);
1268         packet_handler(HCI_EVENT_PACKET, gatt_client->con_handle, event, sizeof(event));
1269         return true; // to trigger requeueing (even if higher layer didn't sent)
1270     }
1271 
1272     return false;
1273 }
1274 
1275 static void gatt_client_run(void){
1276     btstack_linked_item_t *it;
1277     for (it = (btstack_linked_item_t *) gatt_client_connections; it != NULL; it = it->next){
1278         gatt_client_t * gatt_client = (gatt_client_t *) it;
1279 #ifdef ENABLE_GATT_OVER_CLASSIC
1280         if (gatt_client->con_handle == HCI_CON_HANDLE_INVALID) {
1281             continue;
1282         }
1283 
1284         // handle GATT over BR/EDR
1285         if (gatt_client->l2cap_psm != 0){
1286             if (l2cap_can_send_packet_now(gatt_client->l2cap_cid) == false){
1287                 l2cap_request_can_send_now_event(gatt_client->l2cap_cid);
1288                 return;
1289             }
1290             bool packet_sent = gatt_client_run_for_gatt_client(gatt_client);
1291             if (packet_sent){
1292                 // request new permission
1293                 att_dispatch_client_request_can_send_now_event(gatt_client->con_handle);
1294                 // requeue client for fairness and exit
1295                 // note: iterator has become invalid
1296                 btstack_linked_list_remove(&gatt_client_connections, (btstack_linked_item_t *) gatt_client);
1297                 btstack_linked_list_add_tail(&gatt_client_connections, (btstack_linked_item_t *) gatt_client);
1298                 return;
1299             }
1300         }
1301 #endif
1302         // handle GATT over LE
1303         if (!att_dispatch_client_can_send_now(gatt_client->con_handle)) {
1304             att_dispatch_client_request_can_send_now_event(gatt_client->con_handle);
1305             return;
1306         }
1307         bool packet_sent = gatt_client_run_for_gatt_client(gatt_client);
1308         if (packet_sent){
1309             // request new permission
1310             att_dispatch_client_request_can_send_now_event(gatt_client->con_handle);
1311             // requeue client for fairness and exit
1312             // note: iterator has become invalid
1313             btstack_linked_list_remove(&gatt_client_connections, (btstack_linked_item_t *) gatt_client);
1314             btstack_linked_list_add_tail(&gatt_client_connections, (btstack_linked_item_t *) gatt_client);
1315             return;
1316         }
1317     }
1318 }
1319 
1320 static void gatt_client_report_error_if_pending(gatt_client_t *gatt_client, uint8_t att_error_code) {
1321     if (is_ready(gatt_client) == 1) return;
1322     gatt_client_handle_transaction_complete(gatt_client);
1323     emit_gatt_complete_event(gatt_client, att_error_code);
1324 }
1325 
1326 static void gatt_client_handle_reencryption_complete(const uint8_t * packet){
1327     hci_con_handle_t con_handle = sm_event_reencryption_complete_get_handle(packet);
1328     gatt_client_t * gatt_client = gatt_client_get_context_for_handle(con_handle);
1329     if (gatt_client == NULL) return;
1330 
1331     // update security level
1332     gatt_client->security_level = gatt_client_le_security_level_for_connection(con_handle);
1333 
1334     gatt_client->reencryption_result = sm_event_reencryption_complete_get_status(packet);
1335     gatt_client->reencryption_active = false;
1336     gatt_client->wait_for_authentication_complete = 0;
1337 
1338     if (gatt_client->gatt_client_state == P_READY) return;
1339 
1340     switch (sm_event_reencryption_complete_get_status(packet)){
1341         case ERROR_CODE_SUCCESS:
1342             log_info("re-encryption success, retry operation");
1343             break;
1344         case ERROR_CODE_AUTHENTICATION_FAILURE:
1345         case ERROR_CODE_PIN_OR_KEY_MISSING:
1346 #if defined(ENABLE_GATT_CLIENT_PAIRING) && !defined(ENABLE_LE_PROACTIVE_AUTHENTICATION)
1347             if (gatt_client_required_security_level == LEVEL_0) {
1348                 // re-encryption failed for reactive authentication with pairing and we have a pending client request
1349                 // => try to resolve it by deleting bonding information if we started pairing before
1350                 // delete bonding information
1351                 int le_device_db_index = sm_le_device_index(gatt_client->con_handle);
1352                 btstack_assert(le_device_db_index >= 0);
1353                 log_info("reactive auth with pairing: delete bonding and start pairing");
1354 #ifdef ENABLE_LE_PRIVACY_ADDRESS_RESOLUTION
1355                 hci_remove_le_device_db_entry_from_resolving_list((uint16_t) le_device_db_index);
1356 #endif
1357                 le_device_db_remove(le_device_db_index);
1358                 // trigger pairing again
1359                 sm_request_pairing(gatt_client->con_handle);
1360                 break;
1361             }
1362 #endif
1363             // report bonding information missing
1364             gatt_client_handle_transaction_complete(gatt_client);
1365             emit_gatt_complete_event(gatt_client, ATT_ERROR_BONDING_INFORMATION_MISSING);
1366             break;
1367         default:
1368             // report bonding information missing
1369             gatt_client_handle_transaction_complete(gatt_client);
1370             emit_gatt_complete_event(gatt_client, gatt_client->pending_error_code);
1371             break;
1372     }
1373 }
1374 
1375 static void gatt_client_handle_disconnection_complete(const uint8_t * packet){
1376     log_info("GATT Client: HCI_EVENT_DISCONNECTION_COMPLETE");
1377     hci_con_handle_t con_handle = little_endian_read_16(packet,3);
1378     gatt_client_t * gatt_client = gatt_client_get_context_for_handle(con_handle);
1379     if (gatt_client == NULL) return;
1380 
1381     gatt_client_report_error_if_pending(gatt_client, ATT_ERROR_HCI_DISCONNECT_RECEIVED);
1382     gatt_client_timeout_stop(gatt_client);
1383     btstack_linked_list_remove(&gatt_client_connections, (btstack_linked_item_t *) gatt_client);
1384     btstack_memory_gatt_client_free(gatt_client);
1385 }
1386 
1387 static void gatt_client_event_packet_handler(uint8_t packet_type, uint16_t channel, uint8_t *packet, uint16_t size){
1388     UNUSED(channel);    // ok: handling own l2cap events
1389     UNUSED(size);       // ok: there is no channel
1390 
1391     if (packet_type != HCI_EVENT_PACKET) return;
1392 
1393     hci_con_handle_t con_handle;
1394     gatt_client_t * gatt_client;
1395     switch (hci_event_packet_get_type(packet)) {
1396         case HCI_EVENT_DISCONNECTION_COMPLETE:
1397             gatt_client_handle_disconnection_complete(packet);
1398             break;
1399 
1400         // Pairing complete (with/without bonding=storing of pairing information)
1401         case SM_EVENT_PAIRING_COMPLETE:
1402             con_handle = sm_event_pairing_complete_get_handle(packet);
1403             gatt_client = gatt_client_get_context_for_handle(con_handle);
1404             if (gatt_client == NULL) break;
1405 
1406             // update security level
1407             gatt_client->security_level = gatt_client_le_security_level_for_connection(con_handle);
1408 
1409             if (gatt_client->wait_for_authentication_complete){
1410                 gatt_client->wait_for_authentication_complete = 0;
1411                 if (sm_event_pairing_complete_get_status(packet)){
1412                     log_info("pairing failed, report previous error 0x%x", gatt_client->pending_error_code);
1413                     gatt_client_report_error_if_pending(gatt_client, gatt_client->pending_error_code);
1414                 } else {
1415                     log_info("pairing success, retry operation");
1416                 }
1417             }
1418             break;
1419 
1420 #ifdef ENABLE_LE_SIGNED_WRITE
1421         // Identity Resolving completed (no code, gatt_client_run will continue)
1422         case SM_EVENT_IDENTITY_RESOLVING_SUCCEEDED:
1423         case SM_EVENT_IDENTITY_RESOLVING_FAILED:
1424             break;
1425 #endif
1426 
1427         // re-encryption started
1428         case SM_EVENT_REENCRYPTION_STARTED:
1429             con_handle = sm_event_reencryption_complete_get_handle(packet);
1430             gatt_client = gatt_client_get_context_for_handle(con_handle);
1431             if (gatt_client == NULL) break;
1432 
1433             gatt_client->reencryption_active = true;
1434             gatt_client->reencryption_result = ERROR_CODE_SUCCESS;
1435             break;
1436 
1437         // re-encryption complete
1438         case SM_EVENT_REENCRYPTION_COMPLETE:
1439             gatt_client_handle_reencryption_complete(packet);
1440             break;
1441         default:
1442             break;
1443     }
1444 
1445     gatt_client_run();
1446 }
1447 
1448 static void gatt_client_handle_att_read_response(gatt_client_t *gatt_client, uint8_t *packet, uint16_t size) {
1449     switch (gatt_client->gatt_client_state) {
1450         case P_W4_INCLUDED_SERVICE_UUID_WITH_QUERY_RESULT:
1451             if (size >= 17) {
1452                 uint8_t uuid128[16];
1453                 reverse_128(&packet[1], uuid128);
1454                 report_gatt_included_service_uuid128(gatt_client, gatt_client->start_group_handle, uuid128);
1455             }
1456             trigger_next_included_service_query(gatt_client, gatt_client->start_group_handle);
1457             // GATT_EVENT_QUERY_COMPLETE is emitted by trigger_next_xxx when done
1458             break;
1459 
1460         case P_W4_READ_CHARACTERISTIC_VALUE_RESULT:
1461             gatt_client_handle_transaction_complete(gatt_client);
1462             report_gatt_characteristic_value(gatt_client, gatt_client->attribute_handle, &packet[1], size - 1u);
1463             emit_gatt_complete_event(gatt_client, ATT_ERROR_SUCCESS);
1464             break;
1465 
1466         case P_W4_READ_CHARACTERISTIC_DESCRIPTOR_RESULT:
1467             gatt_client_handle_transaction_complete(gatt_client);
1468             report_gatt_characteristic_descriptor(gatt_client, gatt_client->attribute_handle, &packet[1],
1469                                                   size - 1u, 0u);
1470             emit_gatt_complete_event(gatt_client, ATT_ERROR_SUCCESS);
1471             break;
1472 
1473             // Use ATT_READ_REQUEST for first blob of Read Long Characteristic
1474         case P_W4_READ_BLOB_RESULT:
1475             report_gatt_long_characteristic_value_blob(gatt_client, gatt_client->attribute_handle, &packet[1],
1476                                                        size - 1u, gatt_client->attribute_offset);
1477             trigger_next_blob_query(gatt_client, P_W2_SEND_READ_BLOB_QUERY, size - 1u);
1478             // GATT_EVENT_QUERY_COMPLETE is emitted by trigger_next_xxx when done
1479             break;
1480 
1481             // Use ATT_READ_REQUEST for first blob of Read Long Characteristic Descriptor
1482         case P_W4_READ_BLOB_CHARACTERISTIC_DESCRIPTOR_RESULT:
1483             report_gatt_long_characteristic_descriptor(gatt_client, gatt_client->attribute_handle, &packet[1],
1484                                                        size - 1u, gatt_client->attribute_offset);
1485             trigger_next_blob_query(gatt_client, P_W2_SEND_READ_BLOB_CHARACTERISTIC_DESCRIPTOR_QUERY,
1486                                     size - 1u);
1487             // GATT_EVENT_QUERY_COMPLETE is emitted by trigger_next_xxx when done
1488             break;
1489 
1490         default:
1491             break;
1492     }
1493 }
1494 
1495 static void gatt_client_handle_att_read_by_type_response(gatt_client_t *gatt_client, uint8_t *packet, uint16_t size) {
1496     switch (gatt_client->gatt_client_state) {
1497         case P_W4_ALL_CHARACTERISTICS_OF_SERVICE_QUERY_RESULT:
1498             report_gatt_characteristics(gatt_client, packet, size);
1499             trigger_next_characteristic_query(gatt_client,
1500                                               get_last_result_handle_from_characteristics_list(packet, size));
1501             // GATT_EVENT_QUERY_COMPLETE is emitted by trigger_next_xxx when done, or by ATT_ERROR
1502             break;
1503         case P_W4_CHARACTERISTIC_WITH_UUID_QUERY_RESULT:
1504             report_gatt_characteristics(gatt_client, packet, size);
1505             trigger_next_characteristic_query(gatt_client,
1506                                               get_last_result_handle_from_characteristics_list(packet, size));
1507             // GATT_EVENT_QUERY_COMPLETE is emitted by trigger_next_xxx when done, or by ATT_ERROR
1508             break;
1509         case P_W4_INCLUDED_SERVICE_QUERY_RESULT: {
1510             if (size < 2u) break;
1511             uint16_t uuid16 = 0;
1512             uint16_t pair_size = packet[1];
1513 
1514             if (pair_size == 6u) {
1515                 if (size < 8u) break;
1516                 // UUIDs not available, query first included service
1517                 gatt_client->start_group_handle = little_endian_read_16(packet, 2); // ready for next query
1518                 gatt_client->query_start_handle = little_endian_read_16(packet, 4);
1519                 gatt_client->query_end_handle = little_endian_read_16(packet, 6);
1520                 gatt_client->gatt_client_state = P_W2_SEND_INCLUDED_SERVICE_WITH_UUID_QUERY;
1521                 break;
1522             }
1523 
1524             if (pair_size != 8u) break;
1525 
1526             // UUIDs included, report all of them
1527             uint16_t offset;
1528             for (offset = 2u; (offset + 8u) <= size; offset += pair_size) {
1529                 uint16_t include_handle = little_endian_read_16(packet, offset);
1530                 gatt_client->query_start_handle = little_endian_read_16(packet, offset + 2u);
1531                 gatt_client->query_end_handle = little_endian_read_16(packet, offset + 4u);
1532                 uuid16 = little_endian_read_16(packet, offset + 6u);
1533                 report_gatt_included_service_uuid16(gatt_client, include_handle, uuid16);
1534             }
1535 
1536             trigger_next_included_service_query(gatt_client,
1537                                                 get_last_result_handle_from_included_services_list(packet,
1538                                                                                                    size));
1539             // GATT_EVENT_QUERY_COMPLETE is emitted by trigger_next_xxx when done
1540             break;
1541         }
1542 #ifndef ENABLE_GATT_FIND_INFORMATION_FOR_CCC_DISCOVERY
1543         case P_W4_READ_CLIENT_CHARACTERISTIC_CONFIGURATION_QUERY_RESULT:
1544             gatt_client->client_characteristic_configuration_handle = little_endian_read_16(packet, 2);
1545             gatt_client->gatt_client_state = P_W2_WRITE_CLIENT_CHARACTERISTIC_CONFIGURATION;
1546             break;
1547 #endif
1548         case P_W4_READ_BY_TYPE_RESPONSE: {
1549             uint16_t pair_size = packet[1];
1550             // set last result handle to last valid handle, only used if pair_size invalid
1551             uint16_t last_result_handle = 0xffff;
1552             if (pair_size > 2) {
1553                 uint16_t offset;
1554                 for (offset = 2; offset < size; offset += pair_size) {
1555                     uint16_t value_handle = little_endian_read_16(packet, offset);
1556                     report_gatt_characteristic_value(gatt_client, value_handle, &packet[offset + 2u],
1557                                                      pair_size - 2u);
1558                     last_result_handle = value_handle;
1559                 }
1560             }
1561             trigger_next_read_by_type_query(gatt_client, last_result_handle);
1562             break;
1563         }
1564         default:
1565             break;
1566     }
1567 }
1568 
1569 static void gatt_client_handle_att_write_response(gatt_client_t *gatt_client) {
1570     switch (gatt_client->gatt_client_state) {
1571         case P_W4_WRITE_CHARACTERISTIC_VALUE_RESULT:
1572             gatt_client_handle_transaction_complete(gatt_client);
1573             emit_gatt_complete_event(gatt_client, ATT_ERROR_SUCCESS);
1574             break;
1575         case P_W4_CLIENT_CHARACTERISTIC_CONFIGURATION_RESULT:
1576             gatt_client_handle_transaction_complete(gatt_client);
1577             emit_gatt_complete_event(gatt_client, ATT_ERROR_SUCCESS);
1578             break;
1579         case P_W4_WRITE_CHARACTERISTIC_DESCRIPTOR_RESULT:
1580             gatt_client_handle_transaction_complete(gatt_client);
1581             emit_gatt_complete_event(gatt_client, ATT_ERROR_SUCCESS);
1582             break;
1583         default:
1584             break;
1585     }
1586 }
1587 
1588 static void gatt_client_handle_att_response(gatt_client_t * gatt_client, uint8_t * packet, uint16_t size) {
1589     uint8_t error_code;
1590     switch (packet[0]) {
1591         case ATT_EXCHANGE_MTU_RESPONSE: {
1592             if (size < 3u) break;
1593             bool update_att_mtu = true;
1594             uint16_t remote_rx_mtu = little_endian_read_16(packet, 1);
1595             uint16_t local_rx_mtu = l2cap_max_le_mtu();
1596 #ifdef ENABLE_GATT_OVER_CLASSIC
1597             if (gatt_client->l2cap_psm != 0){
1598                 local_rx_mtu = gatt_client->mtu;
1599             } else {
1600                 update_att_mtu = false;
1601             }
1602 #endif
1603             uint16_t mtu = (remote_rx_mtu < local_rx_mtu) ? remote_rx_mtu : local_rx_mtu;
1604 
1605             // set gatt client mtu
1606             gatt_client->mtu = mtu;
1607             gatt_client->mtu_state = MTU_EXCHANGED;
1608 
1609             if (update_att_mtu){
1610                 // set per connection mtu state - for fixed channel
1611                 hci_connection_t *hci_connection = hci_connection_for_handle(gatt_client->con_handle);
1612                 hci_connection->att_connection.mtu = gatt_client->mtu;
1613                 hci_connection->att_connection.mtu_exchanged = true;
1614             }
1615             emit_gatt_mtu_exchanged_result_event(gatt_client, gatt_client->mtu);
1616             break;
1617         }
1618         case ATT_READ_BY_GROUP_TYPE_RESPONSE:
1619             switch (gatt_client->gatt_client_state) {
1620                 case P_W4_SERVICE_QUERY_RESULT:
1621                     report_gatt_services(gatt_client, packet, size);
1622                     trigger_next_service_query(gatt_client, get_last_result_handle_from_service_list(packet, size));
1623                     // GATT_EVENT_QUERY_COMPLETE is emitted by trigger_next_xxx when done
1624                     break;
1625                 default:
1626                     break;
1627             }
1628             break;
1629         case ATT_HANDLE_VALUE_NOTIFICATION:
1630             if (size < 3u) return;
1631             report_gatt_notification(gatt_client, little_endian_read_16(packet, 1u), &packet[3], size - 3u);
1632             return;
1633         case ATT_HANDLE_VALUE_INDICATION:
1634             if (size < 3u) break;
1635             report_gatt_indication(gatt_client, little_endian_read_16(packet, 1u), &packet[3], size - 3u);
1636             gatt_client->send_confirmation = 1;
1637             break;
1638         case ATT_READ_BY_TYPE_RESPONSE:
1639             gatt_client_handle_att_read_by_type_response(gatt_client, packet, size);
1640             break;
1641         case ATT_READ_RESPONSE:
1642             gatt_client_handle_att_read_response(gatt_client, packet, size);
1643             break;
1644         case ATT_FIND_BY_TYPE_VALUE_RESPONSE: {
1645             uint8_t pair_size = 4;
1646             int i;
1647             uint16_t start_group_handle;
1648             uint16_t end_group_handle = 0xffff; // asserts GATT_EVENT_QUERY_COMPLETE is emitted if no results
1649             for (i = 1u; (i + pair_size) <= size; i += pair_size) {
1650                 start_group_handle = little_endian_read_16(packet, i);
1651                 end_group_handle = little_endian_read_16(packet, i + 2);
1652                 emit_gatt_service_query_result_event(gatt_client, start_group_handle, end_group_handle,
1653                                                      gatt_client->uuid128);
1654             }
1655             trigger_next_service_by_uuid_query(gatt_client, end_group_handle);
1656             // GATT_EVENT_QUERY_COMPLETE is emitted by trigger_next_xxx when done
1657             break;
1658         }
1659         case ATT_FIND_INFORMATION_REPLY: {
1660             if (size < 2u) break;
1661 
1662             uint8_t pair_size = 4;
1663             if (packet[1u] == 2u) {
1664                 pair_size = 18;
1665             }
1666             uint16_t offset = 2;
1667 
1668             if (size < (pair_size + offset)) break;
1669             uint16_t last_descriptor_handle = little_endian_read_16(packet, size - pair_size);
1670 
1671 #ifdef ENABLE_GATT_FIND_INFORMATION_FOR_CCC_DISCOVERY
1672             log_info("ENABLE_GATT_FIND_INFORMATION_FOR_CCC_DISCOVERY, state %x", gatt_client->gatt_client_state);
1673             if (gatt_client->gatt_client_state == P_W4_FIND_CLIENT_CHARACTERISTIC_CONFIGURATION_QUERY_RESULT){
1674                 // iterate over descriptors looking for CCC
1675                 if (pair_size == 4){
1676                     while ((offset + 4) <= size){
1677                         uint16_t uuid16 = little_endian_read_16(packet, offset + 2);
1678                         if (uuid16 == GATT_CLIENT_CHARACTERISTICS_CONFIGURATION){
1679                             gatt_client->client_characteristic_configuration_handle = little_endian_read_16(packet, offset);
1680                             gatt_client->gatt_client_state = P_W2_WRITE_CLIENT_CHARACTERISTIC_CONFIGURATION;
1681                             log_info("CCC found %x", gatt_client->client_characteristic_configuration_handle);
1682                             break;
1683                         }
1684                         offset += pair_size;
1685                     }
1686                 }
1687                 if (is_query_done(gatt_client, last_descriptor_handle)){
1688 
1689                 } else {
1690                     // next
1691                     gatt_client->start_group_handle = last_descriptor_handle + 1;
1692                     gatt_client->gatt_client_state = P_W2_SEND_FIND_CLIENT_CHARACTERISTIC_CONFIGURATION_QUERY;
1693                 }
1694                 break;
1695             }
1696 #endif
1697             report_gatt_all_characteristic_descriptors(gatt_client, &packet[2], size - 2u, pair_size);
1698             trigger_next_characteristic_descriptor_query(gatt_client, last_descriptor_handle);
1699             // GATT_EVENT_QUERY_COMPLETE is emitted by trigger_next_xxx when done
1700             break;
1701         }
1702 
1703         case ATT_WRITE_RESPONSE:
1704             gatt_client_handle_att_write_response(gatt_client);
1705             break;
1706 
1707         case ATT_READ_BLOB_RESPONSE: {
1708             uint16_t received_blob_length = size - 1u;
1709             switch (gatt_client->gatt_client_state) {
1710                 case P_W4_READ_BLOB_RESULT:
1711                     report_gatt_long_characteristic_value_blob(gatt_client, gatt_client->attribute_handle, &packet[1],
1712                                                                received_blob_length, gatt_client->attribute_offset);
1713                     trigger_next_blob_query(gatt_client, P_W2_SEND_READ_BLOB_QUERY, received_blob_length);
1714                     // GATT_EVENT_QUERY_COMPLETE is emitted by trigger_next_xxx when done
1715                     break;
1716                 case P_W4_READ_BLOB_CHARACTERISTIC_DESCRIPTOR_RESULT:
1717                     report_gatt_long_characteristic_descriptor(gatt_client, gatt_client->attribute_handle,
1718                                                                &packet[1], received_blob_length,
1719                                                                gatt_client->attribute_offset);
1720                     trigger_next_blob_query(gatt_client, P_W2_SEND_READ_BLOB_CHARACTERISTIC_DESCRIPTOR_QUERY,
1721                                             received_blob_length);
1722                     // GATT_EVENT_QUERY_COMPLETE is emitted by trigger_next_xxx when done
1723                     break;
1724                 default:
1725                     break;
1726             }
1727             break;
1728         }
1729         case ATT_PREPARE_WRITE_RESPONSE:
1730             switch (gatt_client->gatt_client_state) {
1731                 case P_W4_PREPARE_WRITE_SINGLE_RESULT:
1732                     gatt_client_handle_transaction_complete(gatt_client);
1733                     if (is_value_valid(gatt_client, packet, size)) {
1734                         emit_gatt_complete_event(gatt_client, ATT_ERROR_SUCCESS);
1735                     } else {
1736                         emit_gatt_complete_event(gatt_client, ATT_ERROR_DATA_MISMATCH);
1737                     }
1738                     break;
1739 
1740                 case P_W4_PREPARE_WRITE_RESULT: {
1741                     gatt_client->attribute_offset = little_endian_read_16(packet, 3);
1742                     trigger_next_prepare_write_query(gatt_client, P_W2_PREPARE_WRITE, P_W2_EXECUTE_PREPARED_WRITE);
1743                     // GATT_EVENT_QUERY_COMPLETE is emitted by trigger_next_xxx when done
1744                     break;
1745                 }
1746                 case P_W4_PREPARE_WRITE_CHARACTERISTIC_DESCRIPTOR_RESULT: {
1747                     gatt_client->attribute_offset = little_endian_read_16(packet, 3);
1748                     trigger_next_prepare_write_query(gatt_client, P_W2_PREPARE_WRITE_CHARACTERISTIC_DESCRIPTOR,
1749                                                      P_W2_EXECUTE_PREPARED_WRITE_CHARACTERISTIC_DESCRIPTOR);
1750                     // GATT_EVENT_QUERY_COMPLETE is emitted by trigger_next_xxx when done
1751                     break;
1752                 }
1753                 case P_W4_PREPARE_RELIABLE_WRITE_RESULT: {
1754                     if (is_value_valid(gatt_client, packet, size)) {
1755                         gatt_client->attribute_offset = little_endian_read_16(packet, 3);
1756                         trigger_next_prepare_write_query(gatt_client, P_W2_PREPARE_RELIABLE_WRITE,
1757                                                          P_W2_EXECUTE_PREPARED_WRITE);
1758                         // GATT_EVENT_QUERY_COMPLETE is emitted by trigger_next_xxx when done
1759                         break;
1760                     }
1761                     gatt_client->gatt_client_state = P_W2_CANCEL_PREPARED_WRITE_DATA_MISMATCH;
1762                     break;
1763                 }
1764                 default:
1765                     break;
1766             }
1767             break;
1768 
1769         case ATT_EXECUTE_WRITE_RESPONSE:
1770             switch (gatt_client->gatt_client_state) {
1771                 case P_W4_EXECUTE_PREPARED_WRITE_RESULT:
1772                     gatt_client_handle_transaction_complete(gatt_client);
1773                     emit_gatt_complete_event(gatt_client, ATT_ERROR_SUCCESS);
1774                     break;
1775                 case P_W4_CANCEL_PREPARED_WRITE_RESULT:
1776                     gatt_client_handle_transaction_complete(gatt_client);
1777                     emit_gatt_complete_event(gatt_client, ATT_ERROR_SUCCESS);
1778                     break;
1779                 case P_W4_CANCEL_PREPARED_WRITE_DATA_MISMATCH_RESULT:
1780                     gatt_client_handle_transaction_complete(gatt_client);
1781                     emit_gatt_complete_event(gatt_client, ATT_ERROR_DATA_MISMATCH);
1782                     break;
1783                 case P_W4_EXECUTE_PREPARED_WRITE_CHARACTERISTIC_DESCRIPTOR_RESULT:
1784                     gatt_client_handle_transaction_complete(gatt_client);
1785                     emit_gatt_complete_event(gatt_client, ATT_ERROR_SUCCESS);
1786                     break;
1787                 default:
1788                     break;
1789 
1790             }
1791             break;
1792 
1793         case ATT_READ_MULTIPLE_RESPONSE:
1794             switch (gatt_client->gatt_client_state) {
1795                 case P_W4_READ_MULTIPLE_RESPONSE:
1796                     report_gatt_characteristic_value(gatt_client, 0u, &packet[1], size - 1u);
1797                     gatt_client_handle_transaction_complete(gatt_client);
1798                     emit_gatt_complete_event(gatt_client, ATT_ERROR_SUCCESS);
1799                     break;
1800                 default:
1801                     break;
1802             }
1803             break;
1804 
1805         case ATT_ERROR_RESPONSE:
1806             if (size < 5u) return;
1807             error_code = packet[4];
1808             switch (error_code) {
1809                 case ATT_ERROR_ATTRIBUTE_NOT_FOUND: {
1810                     switch (gatt_client->gatt_client_state) {
1811                         case P_W4_SERVICE_QUERY_RESULT:
1812                         case P_W4_SERVICE_WITH_UUID_RESULT:
1813                         case P_W4_INCLUDED_SERVICE_QUERY_RESULT:
1814                         case P_W4_ALL_CHARACTERISTIC_DESCRIPTORS_QUERY_RESULT:
1815                             gatt_client_handle_transaction_complete(gatt_client);
1816                             emit_gatt_complete_event(gatt_client, ATT_ERROR_SUCCESS);
1817                             break;
1818                         case P_W4_ALL_CHARACTERISTICS_OF_SERVICE_QUERY_RESULT:
1819                         case P_W4_CHARACTERISTIC_WITH_UUID_QUERY_RESULT:
1820                             characteristic_end_found(gatt_client, gatt_client->end_group_handle);
1821                             gatt_client_handle_transaction_complete(gatt_client);
1822                             emit_gatt_complete_event(gatt_client, ATT_ERROR_SUCCESS);
1823                             break;
1824                         case P_W4_READ_BY_TYPE_RESPONSE:
1825                             gatt_client_handle_transaction_complete(gatt_client);
1826                             if (gatt_client->start_group_handle == gatt_client->query_start_handle) {
1827                                 emit_gatt_complete_event(gatt_client, ATT_ERROR_ATTRIBUTE_NOT_FOUND);
1828                             } else {
1829                                 emit_gatt_complete_event(gatt_client, ATT_ERROR_SUCCESS);
1830                             }
1831                             break;
1832                         default:
1833                             gatt_client_report_error_if_pending(gatt_client, error_code);
1834                             break;
1835                     }
1836                     break;
1837                 }
1838 
1839 #ifdef ENABLE_GATT_CLIENT_PAIRING
1840 
1841                     case ATT_ERROR_INSUFFICIENT_AUTHENTICATION:
1842                     case ATT_ERROR_INSUFFICIENT_ENCRYPTION_KEY_SIZE:
1843                     case ATT_ERROR_INSUFFICIENT_ENCRYPTION: {
1844 
1845                         // security too low
1846                         if (gatt_client->security_counter > 0) {
1847                             gatt_client_report_error_if_pending(gatt_client, error_code);
1848                             break;
1849                         }
1850                         // start security
1851                         gatt_client->security_counter++;
1852 
1853                         // setup action
1854                         int retry = 1;
1855                         switch (gatt_client->gatt_client_state){
1856                             case P_W4_READ_CHARACTERISTIC_VALUE_RESULT:
1857                                 gatt_client->gatt_client_state = P_W2_SEND_READ_CHARACTERISTIC_VALUE_QUERY ;
1858                                 break;
1859                             case P_W4_READ_BLOB_RESULT:
1860                                 gatt_client->gatt_client_state = P_W2_SEND_READ_BLOB_QUERY;
1861                                 break;
1862                             case P_W4_READ_BY_TYPE_RESPONSE:
1863                                 gatt_client->gatt_client_state = P_W2_SEND_READ_BY_TYPE_REQUEST;
1864                                 break;
1865                             case P_W4_READ_MULTIPLE_RESPONSE:
1866                                 gatt_client->gatt_client_state = P_W2_SEND_READ_MULTIPLE_REQUEST;
1867                                 break;
1868                             case P_W4_WRITE_CHARACTERISTIC_VALUE_RESULT:
1869                                 gatt_client->gatt_client_state = P_W2_SEND_WRITE_CHARACTERISTIC_VALUE;
1870                                 break;
1871                             case P_W4_PREPARE_WRITE_RESULT:
1872                                 gatt_client->gatt_client_state = P_W2_PREPARE_WRITE;
1873                                 break;
1874                             case P_W4_PREPARE_WRITE_SINGLE_RESULT:
1875                                 gatt_client->gatt_client_state = P_W2_PREPARE_WRITE_SINGLE;
1876                                 break;
1877                             case P_W4_PREPARE_RELIABLE_WRITE_RESULT:
1878                                 gatt_client->gatt_client_state = P_W2_PREPARE_RELIABLE_WRITE;
1879                                 break;
1880                             case P_W4_EXECUTE_PREPARED_WRITE_RESULT:
1881                                 gatt_client->gatt_client_state = P_W2_EXECUTE_PREPARED_WRITE;
1882                                 break;
1883                             case P_W4_CANCEL_PREPARED_WRITE_RESULT:
1884                                 gatt_client->gatt_client_state = P_W2_CANCEL_PREPARED_WRITE;
1885                                 break;
1886                             case P_W4_CANCEL_PREPARED_WRITE_DATA_MISMATCH_RESULT:
1887                                 gatt_client->gatt_client_state = P_W2_CANCEL_PREPARED_WRITE_DATA_MISMATCH;
1888                                 break;
1889                             case P_W4_READ_CHARACTERISTIC_DESCRIPTOR_RESULT:
1890                                 gatt_client->gatt_client_state = P_W2_SEND_READ_CHARACTERISTIC_DESCRIPTOR_QUERY;
1891                                 break;
1892                             case P_W4_READ_BLOB_CHARACTERISTIC_DESCRIPTOR_RESULT:
1893                                 gatt_client->gatt_client_state = P_W2_SEND_READ_BLOB_CHARACTERISTIC_DESCRIPTOR_QUERY;
1894                                 break;
1895                             case P_W4_WRITE_CHARACTERISTIC_DESCRIPTOR_RESULT:
1896                                 gatt_client->gatt_client_state = P_W2_SEND_WRITE_CHARACTERISTIC_DESCRIPTOR;
1897                                 break;
1898                             case P_W4_CLIENT_CHARACTERISTIC_CONFIGURATION_RESULT:
1899                                 gatt_client->gatt_client_state = P_W2_WRITE_CLIENT_CHARACTERISTIC_CONFIGURATION;
1900                                 break;
1901                             case P_W4_PREPARE_WRITE_CHARACTERISTIC_DESCRIPTOR_RESULT:
1902                                 gatt_client->gatt_client_state = P_W2_PREPARE_WRITE_CHARACTERISTIC_DESCRIPTOR;
1903                                 break;
1904                             case P_W4_EXECUTE_PREPARED_WRITE_CHARACTERISTIC_DESCRIPTOR_RESULT:
1905                                 gatt_client->gatt_client_state = P_W2_EXECUTE_PREPARED_WRITE_CHARACTERISTIC_DESCRIPTOR;
1906                                 break;
1907 #ifdef ENABLE_LE_SIGNED_WRITE
1908                             case P_W4_SEND_SINGED_WRITE_DONE:
1909                                 gatt_client->gatt_client_state = P_W2_SEND_SIGNED_WRITE;
1910                                 break;
1911 #endif
1912                             default:
1913                                 log_info("retry not supported for state %x", gatt_client->gatt_client_state);
1914                                 retry = 0;
1915                                 break;
1916                         }
1917 
1918                         if (!retry) {
1919                             gatt_client_report_error_if_pending(gatt_client, error_code);
1920                             break;
1921                         }
1922 
1923                         log_info("security error, start pairing");
1924 
1925                         // start pairing for higher security level
1926                         gatt_client->wait_for_authentication_complete = 1;
1927                         gatt_client->pending_error_code = error_code;
1928                         sm_request_pairing(gatt_client->con_handle);
1929                         break;
1930                     }
1931 #endif
1932 
1933                     // nothing we can do about that
1934                 case ATT_ERROR_INSUFFICIENT_AUTHORIZATION:
1935                 default:
1936                     gatt_client_report_error_if_pending(gatt_client, error_code);
1937                     break;
1938             }
1939             break;
1940 
1941         default:
1942             log_info("ATT Handler, unhandled response type 0x%02x", packet[0]);
1943             break;
1944     }
1945 }
1946 
1947 static void gatt_client_att_packet_handler(uint8_t packet_type, uint16_t handle, uint8_t *packet, uint16_t size) {
1948     gatt_client_t *gatt_client;
1949     if (size < 1u) return;
1950 
1951     if (packet_type == HCI_EVENT_PACKET) {
1952         switch (packet[0]) {
1953             case L2CAP_EVENT_CAN_SEND_NOW:
1954                 gatt_client_run();
1955                 break;
1956                 // att_server has negotiated the mtu for this connection, cache if context exists
1957             case ATT_EVENT_MTU_EXCHANGE_COMPLETE:
1958                 if (size < 6u) break;
1959                 gatt_client = gatt_client_get_context_for_handle(handle);
1960                 if (gatt_client == NULL) break;
1961                 gatt_client->mtu = little_endian_read_16(packet, 4);
1962                 break;
1963             default:
1964                 break;
1965         }
1966         return;
1967     }
1968 
1969     if (packet_type != ATT_DATA_PACKET) return;
1970 
1971     // special cases: notifications & indications motivate creating context
1972     switch (packet[0]) {
1973         case ATT_HANDLE_VALUE_NOTIFICATION:
1974         case ATT_HANDLE_VALUE_INDICATION:
1975             gatt_client_provide_context_for_handle(handle, &gatt_client);
1976             break;
1977         default:
1978             gatt_client = gatt_client_get_context_for_handle(handle);
1979             break;
1980     }
1981 
1982     if (gatt_client != NULL) {
1983         gatt_client_handle_att_response(gatt_client, packet, size);
1984         gatt_client_run();
1985     }
1986 }
1987 
1988 #ifdef ENABLE_LE_SIGNED_WRITE
1989 static void att_signed_write_handle_cmac_result(uint8_t hash[8]){
1990     btstack_linked_list_iterator_t it;
1991     btstack_linked_list_iterator_init(&it, &gatt_client_connections);
1992     while (btstack_linked_list_iterator_has_next(&it)){
1993         gatt_client_t * gatt_client = (gatt_client_t *) btstack_linked_list_iterator_next(&it);
1994         if (gatt_client->gatt_client_state == P_W4_CMAC_RESULT){
1995             // store result
1996             (void)memcpy(gatt_client->cmac, hash, 8);
1997             // reverse_64(hash, gatt_client->cmac);
1998             gatt_client->gatt_client_state = P_W2_SEND_SIGNED_WRITE;
1999             gatt_client_run();
2000             return;
2001         }
2002     }
2003 }
2004 
2005 uint8_t gatt_client_signed_write_without_response(btstack_packet_handler_t callback, hci_con_handle_t con_handle, uint16_t value_handle, uint16_t message_len, uint8_t * message){
2006     gatt_client_t * gatt_client;
2007     uint8_t status = gatt_client_provide_context_for_handle(con_handle, &gatt_client);
2008     if (status != ERROR_CODE_SUCCESS){
2009         return status;
2010     }
2011     if (is_ready(gatt_client) == 0){
2012         return GATT_CLIENT_IN_WRONG_STATE;
2013     }
2014 
2015     gatt_client->callback = callback;
2016     gatt_client->attribute_handle = value_handle;
2017     gatt_client->attribute_length = message_len;
2018     gatt_client->attribute_value = message;
2019     gatt_client->gatt_client_state = P_W4_IDENTITY_RESOLVING;
2020     gatt_client_run();
2021     return ERROR_CODE_SUCCESS;
2022 }
2023 #endif
2024 
2025 uint8_t gatt_client_discover_primary_services(btstack_packet_handler_t callback, hci_con_handle_t con_handle){
2026     gatt_client_t * gatt_client;
2027     uint8_t status = gatt_client_provide_context_for_request(con_handle, &gatt_client);
2028     if (status != ERROR_CODE_SUCCESS){
2029         return status;
2030     }
2031 
2032     gatt_client->callback = callback;
2033     gatt_client->start_group_handle = 0x0001;
2034     gatt_client->end_group_handle   = 0xffff;
2035     gatt_client->gatt_client_state = P_W2_SEND_SERVICE_QUERY;
2036     gatt_client->uuid16 = GATT_PRIMARY_SERVICE_UUID;
2037     gatt_client_run();
2038     return ERROR_CODE_SUCCESS;
2039 }
2040 
2041 uint8_t gatt_client_discover_secondary_services(btstack_packet_handler_t callback, hci_con_handle_t con_handle){
2042     gatt_client_t * gatt_client;
2043     uint8_t status = gatt_client_provide_context_for_request(con_handle, &gatt_client);
2044     if (status != ERROR_CODE_SUCCESS){
2045         return status;
2046     }
2047 
2048     gatt_client->callback = callback;
2049     gatt_client->start_group_handle = 0x0001;
2050     gatt_client->end_group_handle   = 0xffff;
2051     gatt_client->gatt_client_state = P_W2_SEND_SERVICE_QUERY;
2052     gatt_client->uuid16 = GATT_SECONDARY_SERVICE_UUID;
2053     gatt_client_run();
2054     return ERROR_CODE_SUCCESS;
2055 }
2056 
2057 uint8_t gatt_client_discover_primary_services_by_uuid16(btstack_packet_handler_t callback, hci_con_handle_t con_handle, uint16_t uuid16){
2058     gatt_client_t * gatt_client;
2059     uint8_t status = gatt_client_provide_context_for_request(con_handle, &gatt_client);
2060     if (status != ERROR_CODE_SUCCESS){
2061         return status;
2062     }
2063 
2064     gatt_client->callback = callback;
2065     gatt_client->start_group_handle = 0x0001;
2066     gatt_client->end_group_handle   = 0xffff;
2067     gatt_client->gatt_client_state = P_W2_SEND_SERVICE_WITH_UUID_QUERY;
2068     gatt_client->uuid16 = uuid16;
2069     uuid_add_bluetooth_prefix((uint8_t*) &(gatt_client->uuid128), gatt_client->uuid16);
2070     gatt_client_run();
2071     return ERROR_CODE_SUCCESS;
2072 }
2073 
2074 uint8_t gatt_client_discover_primary_services_by_uuid128(btstack_packet_handler_t callback, hci_con_handle_t con_handle, const uint8_t * uuid128){
2075     gatt_client_t * gatt_client;
2076     uint8_t status = gatt_client_provide_context_for_request(con_handle, &gatt_client);
2077     if (status != ERROR_CODE_SUCCESS){
2078         return status;
2079     }
2080 
2081     gatt_client->callback = callback;
2082     gatt_client->start_group_handle = 0x0001;
2083     gatt_client->end_group_handle   = 0xffff;
2084     gatt_client->uuid16 = 0;
2085     (void)memcpy(gatt_client->uuid128, uuid128, 16);
2086     gatt_client->gatt_client_state = P_W2_SEND_SERVICE_WITH_UUID_QUERY;
2087     gatt_client_run();
2088     return ERROR_CODE_SUCCESS;
2089 }
2090 
2091 uint8_t gatt_client_discover_characteristics_for_service(btstack_packet_handler_t callback, hci_con_handle_t con_handle, gatt_client_service_t * service){
2092     gatt_client_t * gatt_client;
2093     uint8_t status = gatt_client_provide_context_for_request(con_handle, &gatt_client);
2094     if (status != ERROR_CODE_SUCCESS){
2095         return status;
2096     }
2097 
2098     gatt_client->callback = callback;
2099     gatt_client->start_group_handle = service->start_group_handle;
2100     gatt_client->end_group_handle   = service->end_group_handle;
2101     gatt_client->filter_with_uuid = 0;
2102     gatt_client->characteristic_start_handle = 0;
2103     gatt_client->gatt_client_state = P_W2_SEND_ALL_CHARACTERISTICS_OF_SERVICE_QUERY;
2104     gatt_client_run();
2105     return ERROR_CODE_SUCCESS;
2106 }
2107 
2108 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){
2109     gatt_client_t * gatt_client;
2110     uint8_t status = gatt_client_provide_context_for_request(con_handle, &gatt_client);
2111     if (status != ERROR_CODE_SUCCESS){
2112         return status;
2113     }
2114 
2115     gatt_client->callback = callback;
2116     gatt_client->start_group_handle = service->start_group_handle;
2117     gatt_client->end_group_handle   = service->end_group_handle;
2118     gatt_client->gatt_client_state = P_W2_SEND_INCLUDED_SERVICE_QUERY;
2119 
2120     gatt_client_run();
2121     return ERROR_CODE_SUCCESS;
2122 }
2123 
2124 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){
2125     gatt_client_t * gatt_client;
2126     uint8_t status = gatt_client_provide_context_for_request(con_handle, &gatt_client);
2127     if (status != ERROR_CODE_SUCCESS){
2128         return status;
2129     }
2130 
2131     gatt_client->callback = callback;
2132     gatt_client->start_group_handle = start_handle;
2133     gatt_client->end_group_handle   = end_handle;
2134     gatt_client->filter_with_uuid = 1;
2135     gatt_client->uuid16 = uuid16;
2136     uuid_add_bluetooth_prefix((uint8_t*) &(gatt_client->uuid128), uuid16);
2137     gatt_client->characteristic_start_handle = 0;
2138     gatt_client->gatt_client_state = P_W2_SEND_CHARACTERISTIC_WITH_UUID_QUERY;
2139     gatt_client_run();
2140     return ERROR_CODE_SUCCESS;
2141 }
2142 
2143 uint8_t gatt_client_discover_characteristics_for_handle_range_by_uuid128(btstack_packet_handler_t callback, hci_con_handle_t con_handle, uint16_t start_handle, uint16_t end_handle, const uint8_t * uuid128){
2144     gatt_client_t * gatt_client;
2145     uint8_t status = gatt_client_provide_context_for_request(con_handle, &gatt_client);
2146     if (status != ERROR_CODE_SUCCESS){
2147         return status;
2148     }
2149 
2150     gatt_client->callback = callback;
2151     gatt_client->start_group_handle = start_handle;
2152     gatt_client->end_group_handle   = end_handle;
2153     gatt_client->filter_with_uuid = 1;
2154     gatt_client->uuid16 = 0;
2155     (void)memcpy(gatt_client->uuid128, uuid128, 16);
2156     gatt_client->characteristic_start_handle = 0;
2157     gatt_client->gatt_client_state = P_W2_SEND_CHARACTERISTIC_WITH_UUID_QUERY;
2158     gatt_client_run();
2159     return ERROR_CODE_SUCCESS;
2160 }
2161 
2162 
2163 uint8_t gatt_client_discover_characteristics_for_service_by_uuid16(btstack_packet_handler_t callback, hci_con_handle_t con_handle, gatt_client_service_t * service, uint16_t uuid16){
2164     return gatt_client_discover_characteristics_for_handle_range_by_uuid16(callback, con_handle, service->start_group_handle, service->end_group_handle, uuid16);
2165 }
2166 
2167 uint8_t gatt_client_discover_characteristics_for_service_by_uuid128(btstack_packet_handler_t callback, hci_con_handle_t con_handle, gatt_client_service_t * service, const uint8_t * uuid128){
2168     return gatt_client_discover_characteristics_for_handle_range_by_uuid128(callback, con_handle, service->start_group_handle, service->end_group_handle, uuid128);
2169 }
2170 
2171 uint8_t gatt_client_discover_characteristic_descriptors(btstack_packet_handler_t callback, hci_con_handle_t con_handle, gatt_client_characteristic_t * characteristic){
2172     gatt_client_t * gatt_client;
2173     uint8_t status = gatt_client_provide_context_for_request(con_handle, &gatt_client);
2174     if (status != ERROR_CODE_SUCCESS){
2175         return status;
2176     }
2177 
2178     if (characteristic->value_handle == characteristic->end_handle){
2179         emit_gatt_complete_event(gatt_client, ATT_ERROR_SUCCESS);
2180         return ERROR_CODE_SUCCESS;
2181     }
2182     gatt_client->callback = callback;
2183     gatt_client->start_group_handle = characteristic->value_handle + 1u;
2184     gatt_client->end_group_handle   = characteristic->end_handle;
2185     gatt_client->gatt_client_state = P_W2_SEND_ALL_CHARACTERISTIC_DESCRIPTORS_QUERY;
2186     gatt_client_run();
2187     return ERROR_CODE_SUCCESS;
2188 }
2189 
2190 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){
2191     gatt_client_t * gatt_client;
2192     uint8_t status = gatt_client_provide_context_for_request(con_handle, &gatt_client);
2193     if (status != ERROR_CODE_SUCCESS){
2194         return status;
2195     }
2196 
2197     gatt_client->callback = callback;
2198     gatt_client->attribute_handle = value_handle;
2199     gatt_client->attribute_offset = 0;
2200     gatt_client->gatt_client_state = P_W2_SEND_READ_CHARACTERISTIC_VALUE_QUERY;
2201     gatt_client_run();
2202     return ERROR_CODE_SUCCESS;
2203 }
2204 
2205 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){
2206     gatt_client_t * gatt_client;
2207     uint8_t status = gatt_client_provide_context_for_request(con_handle, &gatt_client);
2208     if (status != ERROR_CODE_SUCCESS){
2209         return status;
2210     }
2211 
2212     gatt_client->callback = callback;
2213     gatt_client->start_group_handle = start_handle;
2214     gatt_client->end_group_handle = end_handle;
2215     gatt_client->query_start_handle = start_handle;
2216     gatt_client->query_end_handle = end_handle;
2217     gatt_client->uuid16 = uuid16;
2218     uuid_add_bluetooth_prefix((uint8_t*) &(gatt_client->uuid128), uuid16);
2219     gatt_client->gatt_client_state = P_W2_SEND_READ_BY_TYPE_REQUEST;
2220     gatt_client_run();
2221     return ERROR_CODE_SUCCESS;
2222 }
2223 
2224 uint8_t gatt_client_read_value_of_characteristics_by_uuid128(btstack_packet_handler_t callback, hci_con_handle_t con_handle, uint16_t start_handle, uint16_t end_handle, const uint8_t * uuid128){
2225     gatt_client_t * gatt_client;
2226     uint8_t status = gatt_client_provide_context_for_request(con_handle, &gatt_client);
2227     if (status != ERROR_CODE_SUCCESS){
2228         return status;
2229     }
2230 
2231     gatt_client->callback = callback;
2232     gatt_client->start_group_handle = start_handle;
2233     gatt_client->end_group_handle = end_handle;
2234     gatt_client->query_start_handle = start_handle;
2235     gatt_client->query_end_handle = end_handle;
2236     gatt_client->uuid16 = 0;
2237     (void)memcpy(gatt_client->uuid128, uuid128, 16);
2238     gatt_client->gatt_client_state = P_W2_SEND_READ_BY_TYPE_REQUEST;
2239     gatt_client_run();
2240     return ERROR_CODE_SUCCESS;
2241 }
2242 
2243 
2244 uint8_t gatt_client_read_value_of_characteristic(btstack_packet_handler_t callback, hci_con_handle_t con_handle, gatt_client_characteristic_t * characteristic){
2245     return gatt_client_read_value_of_characteristic_using_value_handle(callback, con_handle, characteristic->value_handle);
2246 }
2247 
2248 uint8_t gatt_client_read_long_value_of_characteristic_using_value_handle_with_offset(btstack_packet_handler_t callback, hci_con_handle_t con_handle, uint16_t value_handle, uint16_t offset){
2249     gatt_client_t * gatt_client;
2250     uint8_t status = gatt_client_provide_context_for_request(con_handle, &gatt_client);
2251     if (status != ERROR_CODE_SUCCESS){
2252         return status;
2253     }
2254 
2255     gatt_client->callback = callback;
2256     gatt_client->attribute_handle = value_handle;
2257     gatt_client->attribute_offset = offset;
2258     gatt_client->gatt_client_state = P_W2_SEND_READ_BLOB_QUERY;
2259     gatt_client_run();
2260     return ERROR_CODE_SUCCESS;
2261 }
2262 
2263 uint8_t gatt_client_read_long_value_of_characteristic_using_value_handle(btstack_packet_handler_t callback, hci_con_handle_t con_handle, uint16_t value_handle){
2264     return gatt_client_read_long_value_of_characteristic_using_value_handle_with_offset(callback, con_handle, value_handle, 0);
2265 }
2266 
2267 uint8_t gatt_client_read_long_value_of_characteristic(btstack_packet_handler_t callback, hci_con_handle_t con_handle, gatt_client_characteristic_t * characteristic){
2268     return gatt_client_read_long_value_of_characteristic_using_value_handle(callback, con_handle, characteristic->value_handle);
2269 }
2270 
2271 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){
2272     gatt_client_t * gatt_client;
2273     uint8_t status = gatt_client_provide_context_for_request(con_handle, &gatt_client);
2274     if (status != ERROR_CODE_SUCCESS){
2275         return status;
2276     }
2277 
2278     gatt_client->callback = callback;
2279     gatt_client->read_multiple_handle_count = num_value_handles;
2280     gatt_client->read_multiple_handles = value_handles;
2281     gatt_client->gatt_client_state = P_W2_SEND_READ_MULTIPLE_REQUEST;
2282     gatt_client_run();
2283     return ERROR_CODE_SUCCESS;
2284 }
2285 
2286 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){
2287     gatt_client_t * gatt_client;
2288     uint8_t status = gatt_client_provide_context_for_handle(con_handle, &gatt_client);
2289     if (status != ERROR_CODE_SUCCESS){
2290         return status;
2291     }
2292 
2293     if (value_length > (gatt_client->mtu - 3u)) return GATT_CLIENT_VALUE_TOO_LONG;
2294     if (!att_dispatch_client_can_send_now(gatt_client->con_handle)) return GATT_CLIENT_BUSY;
2295 
2296     return att_write_request(gatt_client, ATT_WRITE_COMMAND, value_handle, value_length, value);
2297 }
2298 
2299 uint8_t gatt_client_write_value_of_characteristic(btstack_packet_handler_t callback, hci_con_handle_t con_handle, uint16_t value_handle, uint16_t value_length, uint8_t * value){
2300     gatt_client_t * gatt_client;
2301     uint8_t status = gatt_client_provide_context_for_request(con_handle, &gatt_client);
2302     if (status != ERROR_CODE_SUCCESS){
2303         return status;
2304     }
2305 
2306     gatt_client->callback = callback;
2307     gatt_client->attribute_handle = value_handle;
2308     gatt_client->attribute_length = value_length;
2309     gatt_client->attribute_value = value;
2310     gatt_client->gatt_client_state = P_W2_SEND_WRITE_CHARACTERISTIC_VALUE;
2311     gatt_client_run();
2312     return ERROR_CODE_SUCCESS;
2313 }
2314 
2315 uint8_t gatt_client_write_long_value_of_characteristic_with_offset(btstack_packet_handler_t callback, hci_con_handle_t con_handle, uint16_t value_handle, uint16_t offset, uint16_t value_length, uint8_t * value){
2316     gatt_client_t * gatt_client;
2317     uint8_t status = gatt_client_provide_context_for_request(con_handle, &gatt_client);
2318     if (status != ERROR_CODE_SUCCESS){
2319         return status;
2320     }
2321 
2322     gatt_client->callback = callback;
2323     gatt_client->attribute_handle = value_handle;
2324     gatt_client->attribute_length = value_length;
2325     gatt_client->attribute_offset = offset;
2326     gatt_client->attribute_value = value;
2327     gatt_client->gatt_client_state = P_W2_PREPARE_WRITE;
2328     gatt_client_run();
2329     return ERROR_CODE_SUCCESS;
2330 }
2331 
2332 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){
2333     return gatt_client_write_long_value_of_characteristic_with_offset(callback, con_handle, value_handle, 0, value_length, value);
2334 }
2335 
2336 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){
2337     gatt_client_t * gatt_client;
2338     uint8_t status = gatt_client_provide_context_for_request(con_handle, &gatt_client);
2339     if (status != ERROR_CODE_SUCCESS){
2340         return status;
2341     }
2342 
2343     gatt_client->callback = callback;
2344     gatt_client->attribute_handle = value_handle;
2345     gatt_client->attribute_length = value_length;
2346     gatt_client->attribute_offset = 0;
2347     gatt_client->attribute_value = value;
2348     gatt_client->gatt_client_state = P_W2_PREPARE_RELIABLE_WRITE;
2349     gatt_client_run();
2350     return ERROR_CODE_SUCCESS;
2351 }
2352 
2353 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){
2354     gatt_client_t * gatt_client;
2355     uint8_t status = gatt_client_provide_context_for_request(con_handle, &gatt_client);
2356     if (status != ERROR_CODE_SUCCESS){
2357         return status;
2358     }
2359 
2360     if ( (configuration & GATT_CLIENT_CHARACTERISTICS_CONFIGURATION_NOTIFICATION) &&
2361         ((characteristic->properties & ATT_PROPERTY_NOTIFY) == 0u)) {
2362         log_info("gatt_client_write_client_characteristic_configuration: GATT_CLIENT_CHARACTERISTIC_NOTIFICATION_NOT_SUPPORTED");
2363         return GATT_CLIENT_CHARACTERISTIC_NOTIFICATION_NOT_SUPPORTED;
2364     } else if ( (configuration & GATT_CLIENT_CHARACTERISTICS_CONFIGURATION_INDICATION) &&
2365                ((characteristic->properties & ATT_PROPERTY_INDICATE) == 0u)){
2366         log_info("gatt_client_write_client_characteristic_configuration: GATT_CLIENT_CHARACTERISTIC_INDICATION_NOT_SUPPORTED");
2367         return GATT_CLIENT_CHARACTERISTIC_INDICATION_NOT_SUPPORTED;
2368     }
2369 
2370     gatt_client->callback = callback;
2371     gatt_client->start_group_handle = characteristic->value_handle;
2372     gatt_client->end_group_handle = characteristic->end_handle;
2373     little_endian_store_16(gatt_client->client_characteristic_configuration_value, 0, configuration);
2374 
2375 #ifdef ENABLE_GATT_FIND_INFORMATION_FOR_CCC_DISCOVERY
2376     gatt_client->gatt_client_state = P_W2_SEND_FIND_CLIENT_CHARACTERISTIC_CONFIGURATION_QUERY;
2377 #else
2378     gatt_client->gatt_client_state = P_W2_SEND_READ_CLIENT_CHARACTERISTIC_CONFIGURATION_QUERY;
2379 #endif
2380     gatt_client_run();
2381     return ERROR_CODE_SUCCESS;
2382 }
2383 
2384 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){
2385     gatt_client_t * gatt_client;
2386     uint8_t status = gatt_client_provide_context_for_request(con_handle, &gatt_client);
2387     if (status != ERROR_CODE_SUCCESS){
2388         return status;
2389     }
2390 
2391     gatt_client->callback = callback;
2392     gatt_client->attribute_handle = descriptor_handle;
2393 
2394     gatt_client->gatt_client_state = P_W2_SEND_READ_CHARACTERISTIC_DESCRIPTOR_QUERY;
2395     gatt_client_run();
2396     return ERROR_CODE_SUCCESS;
2397 }
2398 
2399 uint8_t gatt_client_read_characteristic_descriptor(btstack_packet_handler_t callback, hci_con_handle_t con_handle, gatt_client_characteristic_descriptor_t * descriptor){
2400     return gatt_client_read_characteristic_descriptor_using_descriptor_handle(callback, con_handle, descriptor->handle);
2401 }
2402 
2403 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){
2404     gatt_client_t * gatt_client;
2405     uint8_t status = gatt_client_provide_context_for_request(con_handle, &gatt_client);
2406     if (status != ERROR_CODE_SUCCESS){
2407         return status;
2408     }
2409 
2410     gatt_client->callback = callback;
2411     gatt_client->attribute_handle = descriptor_handle;
2412     gatt_client->attribute_offset = offset;
2413     gatt_client->gatt_client_state = P_W2_SEND_READ_BLOB_CHARACTERISTIC_DESCRIPTOR_QUERY;
2414     gatt_client_run();
2415     return ERROR_CODE_SUCCESS;
2416 }
2417 
2418 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){
2419     return gatt_client_read_long_characteristic_descriptor_using_descriptor_handle_with_offset(callback, con_handle, descriptor_handle, 0);
2420 }
2421 
2422 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){
2423     return gatt_client_read_long_characteristic_descriptor_using_descriptor_handle(callback, con_handle, descriptor->handle);
2424 }
2425 
2426 uint8_t gatt_client_write_characteristic_descriptor_using_descriptor_handle(btstack_packet_handler_t callback, hci_con_handle_t con_handle, uint16_t descriptor_handle, uint16_t value_length, uint8_t * value){
2427     gatt_client_t * gatt_client;
2428     uint8_t status = gatt_client_provide_context_for_request(con_handle, &gatt_client);
2429     if (status != ERROR_CODE_SUCCESS){
2430         return status;
2431     }
2432 
2433     gatt_client->callback = callback;
2434     gatt_client->attribute_handle = descriptor_handle;
2435     gatt_client->attribute_length = value_length;
2436     gatt_client->attribute_offset = 0;
2437     gatt_client->attribute_value = value;
2438     gatt_client->gatt_client_state = P_W2_SEND_WRITE_CHARACTERISTIC_DESCRIPTOR;
2439     gatt_client_run();
2440     return ERROR_CODE_SUCCESS;
2441 }
2442 
2443 uint8_t gatt_client_write_characteristic_descriptor(btstack_packet_handler_t callback, hci_con_handle_t con_handle, gatt_client_characteristic_descriptor_t * descriptor, uint16_t value_length, uint8_t * value){
2444     return gatt_client_write_characteristic_descriptor_using_descriptor_handle(callback, con_handle, descriptor->handle, value_length, value);
2445 }
2446 
2447 uint8_t gatt_client_write_long_characteristic_descriptor_using_descriptor_handle_with_offset(btstack_packet_handler_t callback, hci_con_handle_t con_handle, uint16_t descriptor_handle, uint16_t offset, uint16_t value_length, uint8_t * value){
2448     gatt_client_t * gatt_client;
2449     uint8_t status = gatt_client_provide_context_for_request(con_handle, &gatt_client);
2450     if (status != ERROR_CODE_SUCCESS){
2451         return status;
2452     }
2453 
2454     gatt_client->callback = callback;
2455     gatt_client->attribute_handle = descriptor_handle;
2456     gatt_client->attribute_length = value_length;
2457     gatt_client->attribute_offset = offset;
2458     gatt_client->attribute_value = value;
2459     gatt_client->gatt_client_state = P_W2_PREPARE_WRITE_CHARACTERISTIC_DESCRIPTOR;
2460     gatt_client_run();
2461     return ERROR_CODE_SUCCESS;
2462 }
2463 
2464 uint8_t gatt_client_write_long_characteristic_descriptor_using_descriptor_handle(btstack_packet_handler_t callback, hci_con_handle_t con_handle, uint16_t descriptor_handle, uint16_t value_length, uint8_t * value){
2465     return gatt_client_write_long_characteristic_descriptor_using_descriptor_handle_with_offset(callback, con_handle, descriptor_handle, 0, value_length, value);
2466 }
2467 
2468 uint8_t gatt_client_write_long_characteristic_descriptor(btstack_packet_handler_t callback, hci_con_handle_t con_handle, gatt_client_characteristic_descriptor_t * descriptor, uint16_t value_length, uint8_t * value){
2469     return gatt_client_write_long_characteristic_descriptor_using_descriptor_handle(callback, con_handle, descriptor->handle, value_length, value);
2470 }
2471 
2472 /**
2473  * @brief -> gatt complete event
2474  */
2475 uint8_t gatt_client_prepare_write(btstack_packet_handler_t callback, hci_con_handle_t con_handle, uint16_t attribute_handle, uint16_t offset, uint16_t value_length, uint8_t * value){
2476     gatt_client_t * gatt_client;
2477     uint8_t status = gatt_client_provide_context_for_request(con_handle, &gatt_client);
2478     if (status != ERROR_CODE_SUCCESS){
2479         return status;
2480     }
2481 
2482     gatt_client->callback = callback;
2483     gatt_client->attribute_handle = attribute_handle;
2484     gatt_client->attribute_length = value_length;
2485     gatt_client->attribute_offset = offset;
2486     gatt_client->attribute_value = value;
2487     gatt_client->gatt_client_state = P_W2_PREPARE_WRITE_SINGLE;
2488     gatt_client_run();
2489     return ERROR_CODE_SUCCESS;
2490 }
2491 
2492 /**
2493  * @brief -> gatt complete event
2494  */
2495 uint8_t gatt_client_execute_write(btstack_packet_handler_t callback, hci_con_handle_t con_handle){
2496     gatt_client_t * gatt_client;
2497     uint8_t status = gatt_client_provide_context_for_request(con_handle, &gatt_client);
2498     if (status != ERROR_CODE_SUCCESS){
2499         return status;
2500     }
2501 
2502     gatt_client->callback = callback;
2503     gatt_client->gatt_client_state = P_W2_EXECUTE_PREPARED_WRITE;
2504     gatt_client_run();
2505     return ERROR_CODE_SUCCESS;
2506 }
2507 
2508 /**
2509  * @brief -> gatt complete event
2510  */
2511 uint8_t gatt_client_cancel_write(btstack_packet_handler_t callback, hci_con_handle_t con_handle){
2512     gatt_client_t * gatt_client;
2513     uint8_t status = gatt_client_provide_context_for_request(con_handle, &gatt_client);
2514     if (status != ERROR_CODE_SUCCESS){
2515         return status;
2516     }
2517 
2518     gatt_client->callback = callback;
2519     gatt_client->gatt_client_state = P_W2_CANCEL_PREPARED_WRITE;
2520     gatt_client_run();
2521     return ERROR_CODE_SUCCESS;
2522 }
2523 
2524 void gatt_client_deserialize_service(const uint8_t *packet, int offset, gatt_client_service_t * service){
2525     service->start_group_handle = little_endian_read_16(packet, offset);
2526     service->end_group_handle = little_endian_read_16(packet, offset + 2);
2527     reverse_128(&packet[offset + 4], service->uuid128);
2528     if (uuid_has_bluetooth_prefix(service->uuid128)){
2529         service->uuid16 = big_endian_read_32(service->uuid128, 0);
2530     } else {
2531         service->uuid16 = 0;
2532     }
2533 }
2534 
2535 void gatt_client_deserialize_characteristic(const uint8_t * packet, int offset, gatt_client_characteristic_t * characteristic){
2536     characteristic->start_handle = little_endian_read_16(packet, offset);
2537     characteristic->value_handle = little_endian_read_16(packet, offset + 2);
2538     characteristic->end_handle = little_endian_read_16(packet, offset + 4);
2539     characteristic->properties = little_endian_read_16(packet, offset + 6);
2540     reverse_128(&packet[offset+8], characteristic->uuid128);
2541     if (uuid_has_bluetooth_prefix(characteristic->uuid128)){
2542         characteristic->uuid16 = big_endian_read_32(characteristic->uuid128, 0);
2543     } else {
2544         characteristic->uuid16 = 0;
2545     }
2546 }
2547 
2548 void gatt_client_deserialize_characteristic_descriptor(const uint8_t * packet, int offset, gatt_client_characteristic_descriptor_t * descriptor){
2549     descriptor->handle = little_endian_read_16(packet, offset);
2550     reverse_128(&packet[offset+2], descriptor->uuid128);
2551     if (uuid_has_bluetooth_prefix(descriptor->uuid128)){
2552         descriptor->uuid16 = big_endian_read_32(descriptor->uuid128, 0);
2553     } else {
2554         descriptor->uuid16 = 0;
2555     }
2556 }
2557 
2558 void gatt_client_send_mtu_negotiation(btstack_packet_handler_t callback, hci_con_handle_t con_handle){
2559     gatt_client_t * gatt_client;
2560     uint8_t status = gatt_client_provide_context_for_handle(con_handle, &gatt_client);
2561     if (status != ERROR_CODE_SUCCESS){
2562         return;
2563     }
2564     if (gatt_client->mtu_state == MTU_AUTO_EXCHANGE_DISABLED){
2565         gatt_client->callback = callback;
2566         gatt_client->mtu_state = SEND_MTU_EXCHANGE;
2567         gatt_client_run();
2568     }
2569 }
2570 
2571 uint8_t gatt_client_request_to_write_without_response(btstack_context_callback_registration_t * callback_registration, hci_con_handle_t con_handle){
2572     gatt_client_t * gatt_client;
2573     uint8_t status = gatt_client_provide_context_for_handle(con_handle, &gatt_client);
2574     if (status != ERROR_CODE_SUCCESS){
2575         return status;
2576     }
2577     bool added = btstack_linked_list_add_tail(&gatt_client->write_without_response_requests, (btstack_linked_item_t*) callback_registration);
2578     att_dispatch_client_request_can_send_now_event(gatt_client->con_handle);
2579     if (added){
2580         return ERROR_CODE_SUCCESS;
2581     } else {
2582         return ERROR_CODE_COMMAND_DISALLOWED;
2583     }
2584 }
2585 
2586 uint8_t gatt_client_request_to_send_gatt_query(btstack_context_callback_registration_t * callback_registration, hci_con_handle_t con_handle){
2587     gatt_client_t * gatt_client;
2588     uint8_t status = gatt_client_provide_context_for_handle(con_handle, &gatt_client);
2589     if (status != ERROR_CODE_SUCCESS){
2590         return status;
2591     }
2592     bool added = btstack_linked_list_add_tail(&gatt_client->query_requests, (btstack_linked_item_t*) callback_registration);
2593     gatt_client_notify_can_send_query(gatt_client);
2594     if (added){
2595         return ERROR_CODE_SUCCESS;
2596     } else {
2597         return ERROR_CODE_COMMAND_DISALLOWED;
2598     }
2599 }
2600 
2601 uint8_t gatt_client_request_can_write_without_response_event(btstack_packet_handler_t callback, hci_con_handle_t con_handle){
2602     gatt_client_t * gatt_client;
2603     uint8_t status = gatt_client_provide_context_for_handle(con_handle, &gatt_client);
2604     if (status != ERROR_CODE_SUCCESS){
2605         return status;
2606     }
2607     if (gatt_client->write_without_response_callback != NULL){
2608         return GATT_CLIENT_IN_WRONG_STATE;
2609     }
2610     gatt_client->write_without_response_callback = callback;
2611     att_dispatch_client_request_can_send_now_event(gatt_client->con_handle);
2612     return ERROR_CODE_SUCCESS;
2613 }
2614 
2615 #ifdef ENABLE_GATT_OVER_CLASSIC
2616 
2617 #include "hci_event.h"
2618 
2619 // single active SDP query
2620 static gatt_client_t * gatt_client_classic_active_sdp_query;
2621 
2622 // macos protocol descriptor list requires 16 bytes
2623 static uint8_t gatt_client_classic_sdp_buffer[32];
2624 
2625 static const hci_event_t gatt_client_connected = {
2626         GATT_EVENT_CONNECTED, 0, "1BH"
2627 };
2628 
2629 static const hci_event_t gatt_client_disconnected = {
2630         GATT_EVENT_DISCONNECTED, 0, "H"
2631 };
2632 
2633 static gatt_client_t * gatt_client_get_context_for_classic_addr(bd_addr_t addr){
2634     btstack_linked_item_t *it;
2635     for (it = (btstack_linked_item_t *) gatt_client_connections; it != NULL; it = it->next){
2636         gatt_client_t * gatt_client = (gatt_client_t *) it;
2637         if (memcmp(gatt_client->addr, addr, 6) == 0){
2638             return gatt_client;
2639         }
2640     }
2641     return NULL;
2642 }
2643 
2644 static gatt_client_t * gatt_client_get_context_for_l2cap_cid(uint16_t l2cap_cid){
2645     btstack_linked_item_t *it;
2646     for (it = (btstack_linked_item_t *) gatt_client_connections; it != NULL; it = it->next){
2647         gatt_client_t * gatt_client = (gatt_client_t *) it;
2648         if (gatt_client->l2cap_cid == l2cap_cid){
2649             return gatt_client;
2650         }
2651     }
2652     return NULL;
2653 }
2654 
2655 static void gatt_client_classic_handle_connected(gatt_client_t * gatt_client, uint8_t status){
2656     bd_addr_t addr;
2657     // cppcheck-suppress uninitvar ; addr is reported as uninitialized although it's the destination of the memcpy
2658     memcpy(addr, gatt_client->addr, 6);
2659     hci_con_handle_t con_handle = gatt_client->con_handle;
2660     btstack_packet_handler_t callback = gatt_client->callback;
2661     if (status != ERROR_CODE_SUCCESS){
2662         btstack_linked_list_remove(&gatt_client_connections, (btstack_linked_item_t *) gatt_client);
2663         btstack_memory_gatt_client_free(gatt_client);
2664     }
2665     uint8_t buffer[20];
2666     uint16_t len = hci_event_create_from_template_and_arguments(buffer, sizeof(buffer), &gatt_client_connected, status, addr,
2667                                                                 con_handle);
2668     (*callback)(HCI_EVENT_PACKET, 0, buffer, len);
2669 }
2670 
2671 static void gatt_client_classic_handle_disconnected(gatt_client_t * gatt_client){
2672 
2673     gatt_client_report_error_if_pending(gatt_client, ATT_ERROR_HCI_DISCONNECT_RECEIVED);
2674     gatt_client_timeout_stop(gatt_client);
2675 
2676     hci_con_handle_t con_handle = gatt_client->con_handle;
2677     btstack_packet_handler_t callback = gatt_client->callback;
2678     btstack_linked_list_remove(&gatt_client_connections, (btstack_linked_item_t *) gatt_client);
2679     btstack_memory_gatt_client_free(gatt_client);
2680 
2681     uint8_t buffer[20];
2682     uint16_t len = hci_event_create_from_template_and_arguments(buffer, sizeof(buffer), &gatt_client_disconnected, con_handle);
2683     (*callback)(HCI_EVENT_PACKET, 0, buffer, len);
2684 }
2685 
2686 static void gatt_client_l2cap_handler(uint8_t packet_type, uint16_t channel, uint8_t *packet, uint16_t size){
2687     gatt_client_t * gatt_client = NULL;
2688     uint8_t status;
2689     switch (packet_type){
2690         case HCI_EVENT_PACKET:
2691             switch (hci_event_packet_get_type(packet)) {
2692                 case L2CAP_EVENT_CHANNEL_OPENED:
2693                     status = l2cap_event_channel_opened_get_status(packet);
2694                     gatt_client = gatt_client_get_context_for_l2cap_cid(l2cap_event_channel_opened_get_local_cid(packet));
2695                     btstack_assert(gatt_client != NULL);
2696                     // if status != 0, gatt_client will be discarded
2697                     gatt_client->gatt_client_state = P_READY;
2698                     gatt_client->con_handle = l2cap_event_channel_opened_get_handle(packet);
2699                     gatt_client->mtu = l2cap_event_channel_opened_get_remote_mtu(packet);
2700                     gatt_client_classic_handle_connected(gatt_client, status);
2701                     break;
2702                 case L2CAP_EVENT_CHANNEL_CLOSED:
2703                     gatt_client = gatt_client_get_context_for_l2cap_cid(l2cap_event_channel_closed_get_local_cid(packet));
2704                     gatt_client_classic_handle_disconnected(gatt_client);
2705                     break;
2706                 default:
2707                     break;
2708             }
2709             break;
2710         case L2CAP_DATA_PACKET:
2711             gatt_client = gatt_client_get_context_for_l2cap_cid(channel);
2712             btstack_assert(gatt_client != NULL);
2713             gatt_client_handle_att_response(gatt_client, packet, size);
2714             gatt_client_run();
2715             break;
2716         default:
2717             break;
2718     }
2719 }
2720 
2721 static void gatt_client_handle_sdp_client_query_attribute_value(gatt_client_t * connection, uint8_t *packet){
2722     des_iterator_t des_list_it;
2723     des_iterator_t prot_it;
2724 
2725     if (sdp_event_query_attribute_byte_get_attribute_length(packet) <= sizeof(gatt_client_classic_sdp_buffer)) {
2726         gatt_client_classic_sdp_buffer[sdp_event_query_attribute_byte_get_data_offset(packet)] = sdp_event_query_attribute_byte_get_data(packet);
2727         if ((uint16_t)(sdp_event_query_attribute_byte_get_data_offset(packet)+1) == sdp_event_query_attribute_byte_get_attribute_length(packet)) {
2728             switch(sdp_event_query_attribute_byte_get_attribute_id(packet)) {
2729                 case BLUETOOTH_ATTRIBUTE_PROTOCOL_DESCRIPTOR_LIST:
2730                     for (des_iterator_init(&des_list_it, gatt_client_classic_sdp_buffer); des_iterator_has_more(&des_list_it); des_iterator_next(&des_list_it)) {
2731                         uint8_t       *des_element;
2732                         uint8_t       *element;
2733                         uint32_t       uuid;
2734 
2735                         if (des_iterator_get_type(&des_list_it) != DE_DES) continue;
2736 
2737                         des_element = des_iterator_get_element(&des_list_it);
2738                         des_iterator_init(&prot_it, des_element);
2739                         element = des_iterator_get_element(&prot_it);
2740 
2741                         if (de_get_element_type(element) != DE_UUID) continue;
2742 
2743                         uuid = de_get_uuid32(element);
2744                         des_iterator_next(&prot_it);
2745                         // we assume that the even if there are both roles supported, remote device uses the same psm and avdtp version for both
2746                         switch (uuid){
2747                             case BLUETOOTH_PROTOCOL_L2CAP:
2748                                 if (!des_iterator_has_more(&prot_it)) continue;
2749                                 de_element_get_uint16(des_iterator_get_element(&prot_it), &connection->l2cap_psm);
2750                                 break;
2751                             default:
2752                                 break;
2753                         }
2754                     }
2755                     break;
2756 
2757                 default:
2758                     break;
2759             }
2760         }
2761     }
2762 }
2763 
2764 static void gatt_client_classic_sdp_handler(uint8_t packet_type, uint16_t handle, uint8_t *packet, uint16_t size){
2765     gatt_client_t * gatt_client = gatt_client_classic_active_sdp_query;
2766     btstack_assert(gatt_client != NULL);
2767     uint8_t status;
2768 
2769     // TODO: handle sdp events, get l2cap psm
2770     switch (hci_event_packet_get_type(packet)){
2771         case SDP_EVENT_QUERY_ATTRIBUTE_VALUE:
2772             gatt_client_handle_sdp_client_query_attribute_value(gatt_client, packet);
2773             // TODO:
2774             return;
2775         case SDP_EVENT_QUERY_COMPLETE:
2776             status = sdp_event_query_complete_get_status(packet);
2777             gatt_client_classic_active_sdp_query = NULL;
2778             log_info("l2cap psm: %0x, status %02x", gatt_client->l2cap_psm, status);
2779             if (status != ERROR_CODE_SUCCESS) break;
2780             if (gatt_client->l2cap_psm == 0) {
2781                 status = SDP_SERVICE_NOT_FOUND;
2782                 break;
2783             }
2784             break;
2785         default:
2786             btstack_assert(false);
2787             return;
2788     }
2789 
2790     // done
2791     if (status == ERROR_CODE_SUCCESS){
2792         gatt_client->gatt_client_state = P_W4_L2CAP_CONNECTION;
2793         status = l2cap_create_channel(gatt_client_l2cap_handler, gatt_client->addr, gatt_client->l2cap_psm, 0xffff,
2794                              &gatt_client->l2cap_cid);
2795     }
2796     if (status != ERROR_CODE_SUCCESS) {
2797         gatt_client_classic_handle_connected(gatt_client, status);
2798     }
2799 }
2800 
2801 static void gatt_client_classic_sdp_start(void * context){
2802     gatt_client_classic_active_sdp_query = (gatt_client_t *) context;
2803     gatt_client_classic_active_sdp_query->gatt_client_state = P_W4_SDP_QUERY;
2804     sdp_client_query_uuid16(gatt_client_classic_sdp_handler, gatt_client_classic_active_sdp_query->addr, ORG_BLUETOOTH_SERVICE_GENERIC_ATTRIBUTE);
2805 }
2806 
2807 uint8_t gatt_client_classic_connect(btstack_packet_handler_t callback, bd_addr_t addr){
2808     gatt_client_t * gatt_client = gatt_client_get_context_for_classic_addr(addr);
2809     if (gatt_client != NULL){
2810         return ERROR_CODE_ACL_CONNECTION_ALREADY_EXISTS;
2811     }
2812     gatt_client = btstack_memory_gatt_client_get();
2813     if (gatt_client == NULL){
2814         return ERROR_CODE_MEMORY_CAPACITY_EXCEEDED;
2815     }
2816     // init state
2817     gatt_client->bearer_type = ATT_BEARER_UNENHANCED_CLASSIC;
2818     gatt_client->con_handle = HCI_CON_HANDLE_INVALID;
2819     memcpy(gatt_client->addr, addr, 6);
2820     gatt_client->mtu = ATT_DEFAULT_MTU;
2821     gatt_client->security_level = LEVEL_0;
2822     gatt_client->mtu_state = MTU_AUTO_EXCHANGE_DISABLED;
2823     gatt_client->gatt_client_state = P_W2_SDP_QUERY;
2824     gatt_client->sdp_query_request.callback = &gatt_client_classic_sdp_start;
2825     gatt_client->sdp_query_request.context = gatt_client;
2826     gatt_client->callback = callback;
2827     btstack_linked_list_add(&gatt_client_connections, (btstack_linked_item_t*)gatt_client);
2828     sdp_client_register_query_callback(&gatt_client->sdp_query_request);
2829     return ERROR_CODE_SUCCESS;
2830 }
2831 
2832 uint8_t gatt_client_classic_disconnect(btstack_packet_handler_t callback, hci_con_handle_t con_handle){
2833     gatt_client_t * gatt_client = gatt_client_get_context_for_handle(con_handle);
2834     if (gatt_client == NULL){
2835         return ERROR_CODE_UNKNOWN_CONNECTION_IDENTIFIER;
2836     }
2837     gatt_client->callback = callback;
2838     return l2cap_disconnect(gatt_client->l2cap_cid);
2839 }
2840 #endif
2841 
2842 #ifdef FUZZING_BUILD_MODE_UNSAFE_FOR_PRODUCTION
2843 void gatt_client_att_packet_handler_fuzz(uint8_t packet_type, uint16_t handle, uint8_t *packet, uint16_t size){
2844     gatt_client_att_packet_handler(packet_type, handle, packet, size);
2845 }
2846 
2847 uint8_t gatt_client_get_client(hci_con_handle_t con_handle, gatt_client_t ** out_gatt_client){
2848     uint8_t status = gatt_client_provide_context_for_handle(con_handle, out_gatt_client);
2849     return status;
2850 }
2851 #endif
2852