xref: /btstack/src/classic/avrcp.c (revision c3d92d4cd669b8b3faad1c4bbd1a975c7264c98f)
1 /*
2  * Copyright (C) 2016 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__ "avrcp.c"
39 
40 #include <stdint.h>
41 #include <string.h>
42 // snprintf
43 #include <stdio.h>
44 
45 #include "bluetooth_psm.h"
46 #include "bluetooth_sdp.h"
47 #include "btstack_debug.h"
48 #include "btstack_event.h"
49 #include "btstack_memory.h"
50 #include "classic/sdp_client.h"
51 #include "classic/sdp_util.h"
52 #include "classic/avrcp.h"
53 
54 
55 typedef struct {
56     uint8_t  parse_sdp_record;
57     uint32_t record_id;
58     uint16_t avrcp_cid;
59     uint16_t avrcp_l2cap_psm;
60     uint16_t avrcp_version;
61 
62     uint16_t browsing_l2cap_psm;
63     uint16_t browsing_version;
64 } avrcp_sdp_query_context_t;
65 
66 static void avrcp_packet_handler(uint8_t packet_type, uint16_t channel, uint8_t *packet, uint16_t size);
67 
68 static const char * avrcp_default_controller_service_name = "BTstack AVRCP Controller Service";
69 static const char * avrcp_default_controller_service_provider_name = "BTstack AVRCP Controller Service Provider";
70 static const char * avrcp_defaul_target_service_name = "BTstack AVRCP Target Service";
71 static const char * avrcp_default_target_service_provider_name = "BTstack AVRCP Target Service Provider";
72 
73 static const char * avrcp_subunit_type_name[] = {
74         "MONITOR", "AUDIO", "PRINTER", "DISC", "TAPE_RECORDER_PLAYER", "TUNER",
75         "CA", "CAMERA", "RESERVED", "PANEL", "BULLETIN_BOARD", "CAMERA_STORAGE",
76         "VENDOR_UNIQUE", "RESERVED_FOR_ALL_SUBUNIT_TYPES",
77         "EXTENDED_TO_NEXT_BYTE", "UNIT", "ERROR"
78 };
79 
80 // default subunit info: single PANEL subunit
81 static const uint8_t avrcp_default_subunit_info[] = { AVRCP_SUBUNIT_TYPE_PANEL << 3};
82 
83 // globals
84 static bool avrcp_l2cap_service_registered = false;
85 
86 // connections
87 static uint16_t                 avrcp_cid_counter;
88 static btstack_linked_list_t    avrcp_connections;
89 
90 // higher layer callbacks
91 static btstack_packet_handler_t avrcp_callback;
92 static btstack_packet_handler_t avrcp_controller_packet_handler;
93 static btstack_packet_handler_t avrcp_target_packet_handler;
94 
95 // sdp query
96 static btstack_context_callback_registration_t avrcp_sdp_query_registration;
97 static avrcp_sdp_query_context_t               avrcp_sdp_query_context;
98 static uint8_t                                 avrcp_sdp_query_attribute_value[45];
99 static const unsigned int                      avrcp_sdp_query_attribute_value_buffer_size = sizeof(avrcp_sdp_query_attribute_value);
100 
101 
102 const char * avrcp_subunit2str(uint16_t index){
103     if (index <= 11) return avrcp_subunit_type_name[index];
104     if ((index >= 0x1C) && (index <= 0x1F)) return avrcp_subunit_type_name[index - 0x10];
105     return avrcp_subunit_type_name[16];
106 }
107 
108 static const char * avrcp_event_name[] = {
109     "ERROR", "PLAYBACK_STATUS_CHANGED",
110     "TRACK_CHANGED", "TRACK_REACHED_END", "TRACK_REACHED_START",
111     "PLAYBACK_POS_CHANGED", "BATT_STATUS_CHANGED", "SYSTEM_STATUS_CHANGED",
112     "PLAYER_APPLICATION_SETTING_CHANGED", "NOW_PLAYING_CONTENT_CHANGED",
113     "AVAILABLE_PLAYERS_CHANGED", "ADDRESSED_PLAYER_CHANGED", "UIDS_CHANGED", "VOLUME_CHANGED"
114 };
115 const char * avrcp_event2str(uint16_t index){
116     if (index <= 0x0d) return avrcp_event_name[index];
117     return avrcp_event_name[0];
118 }
119 
120 static const char * avrcp_operation_name[] = {
121     "SKIP", NULL, NULL, NULL, NULL,
122     "VOLUME_UP", "VOLUME_DOWN", "MUTE", "PLAY", "STOP", "PAUSE", NULL,
123     "REWIND", "FAST_FORWARD", NULL, "FORWARD", "BACKWARD" // 0x4C
124 };
125 
126 const char * avrcp_operation2str(uint8_t operation_id){
127     char * name = NULL;
128     if ((operation_id >= AVRCP_OPERATION_ID_SKIP) && (operation_id <= AVRCP_OPERATION_ID_BACKWARD)){
129         name = (char *)avrcp_operation_name[operation_id - AVRCP_OPERATION_ID_SKIP];
130     }
131     if (name == NULL){
132         static char buffer[13];
133         snprintf(buffer, sizeof(buffer), "Unknown 0x%02x", operation_id);
134         buffer[sizeof(buffer)-1] = 0;
135         return buffer;
136     } else {
137         return name;
138     }
139 }
140 
141 static const char * avrcp_media_attribute_id_name[] = {
142     "NONE", "TITLE", "ARTIST", "ALBUM", "TRACK", "TOTAL TRACKS", "GENRE", "SONG LENGTH"
143 };
144 const char * avrcp_attribute2str(uint8_t index){
145     if ((index >= 1) && (index <= 7)) return avrcp_media_attribute_id_name[index];
146     return avrcp_media_attribute_id_name[0];
147 }
148 
149 static const char * avrcp_play_status_name[] = {
150     "STOPPED", "PLAYING", "PAUSED", "FORWARD SEEK", "REVERSE SEEK",
151     "ERROR" // 0xFF
152 };
153 const char * avrcp_play_status2str(uint8_t index){
154     if ((index >= 1) && (index <= 4)) return avrcp_play_status_name[index];
155     return avrcp_play_status_name[5];
156 }
157 
158 static const char * avrcp_ctype_name[] = {
159     "CONTROL",
160     "STATUS",
161     "SPECIFIC_INQUIRY",
162     "NOTIFY",
163     "GENERAL_INQUIRY",
164     "RESERVED5",
165     "RESERVED6",
166     "RESERVED7",
167     "NOT IMPLEMENTED IN REMOTE",
168     "ACCEPTED BY REMOTE",
169     "REJECTED BY REMOTE",
170     "IN_TRANSITION",
171     "IMPLEMENTED_STABLE",
172     "CHANGED_STABLE",
173     "RESERVED",
174     "INTERIM"
175 };
176 const char * avrcp_ctype2str(uint8_t index){
177     if (index < sizeof(avrcp_ctype_name)){
178         return avrcp_ctype_name[index];
179     }
180     return "NONE";
181 }
182 
183 static const char * avrcp_shuffle_mode_name[] = {
184     "SHUFFLE OFF",
185     "SHUFFLE ALL TRACKS",
186     "SHUFFLE GROUP"
187 };
188 
189 const char * avrcp_shuffle2str(uint8_t index){
190     if ((index >= 1) && (index <= 3)) return avrcp_shuffle_mode_name[index-1];
191     return "NONE";
192 }
193 
194 static const char * avrcp_repeat_mode_name[] = {
195     "REPEAT OFF",
196     "REPEAT SINGLE TRACK",
197     "REPEAT ALL TRACKS",
198     "REPEAT GROUP"
199 };
200 
201 const char * avrcp_repeat2str(uint8_t index){
202     if ((index >= 1) && (index <= 4)) return avrcp_repeat_mode_name[index-1];
203     return "NONE";
204 }
205 
206 btstack_linked_list_t avrcp_get_connections(void){
207     return avrcp_connections;
208 }
209 
210 uint8_t avrcp_cmd_opcode(uint8_t *packet, uint16_t size){
211     uint8_t cmd_opcode_index = 5;
212     if (cmd_opcode_index > size) return AVRCP_CMD_OPCODE_UNDEFINED;
213     return packet[cmd_opcode_index];
214 }
215 
216 void avrcp_create_sdp_record(uint8_t controller, uint8_t * service, uint32_t service_record_handle, uint8_t browsing, uint16_t supported_features,
217     const char * service_name, const char * service_provider_name){
218     uint8_t* attribute;
219     de_create_sequence(service);
220 
221     // 0x0000 "Service Record Handle"
222     de_add_number(service, DE_UINT, DE_SIZE_16, BLUETOOTH_ATTRIBUTE_SERVICE_RECORD_HANDLE);
223     de_add_number(service, DE_UINT, DE_SIZE_32, service_record_handle);
224 
225     // 0x0001 "Service Class ID List"
226     de_add_number(service,  DE_UINT, DE_SIZE_16, BLUETOOTH_ATTRIBUTE_SERVICE_CLASS_ID_LIST);
227     attribute = de_push_sequence(service);
228     {
229         if (controller){
230             de_add_number(attribute, DE_UUID, DE_SIZE_16, BLUETOOTH_SERVICE_CLASS_AV_REMOTE_CONTROL);
231             de_add_number(attribute, DE_UUID, DE_SIZE_16, BLUETOOTH_SERVICE_CLASS_AV_REMOTE_CONTROL_CONTROLLER);
232         } else {
233             de_add_number(attribute, DE_UUID, DE_SIZE_16, BLUETOOTH_SERVICE_CLASS_AV_REMOTE_CONTROL_TARGET);
234         }
235     }
236     de_pop_sequence(service, attribute);
237 
238     // 0x0004 "Protocol Descriptor List"
239     de_add_number(service,  DE_UINT, DE_SIZE_16, BLUETOOTH_ATTRIBUTE_PROTOCOL_DESCRIPTOR_LIST);
240     attribute = de_push_sequence(service);
241     {
242         uint8_t* l2cpProtocol = de_push_sequence(attribute);
243         {
244             de_add_number(l2cpProtocol,  DE_UUID, DE_SIZE_16, BLUETOOTH_PROTOCOL_L2CAP);
245             de_add_number(l2cpProtocol,  DE_UINT, DE_SIZE_16, BLUETOOTH_PSM_AVCTP);
246         }
247         de_pop_sequence(attribute, l2cpProtocol);
248 
249         uint8_t* avctpProtocol = de_push_sequence(attribute);
250         {
251             de_add_number(avctpProtocol,  DE_UUID, DE_SIZE_16, BLUETOOTH_PROTOCOL_AVCTP);  // avctpProtocol_service
252             de_add_number(avctpProtocol,  DE_UINT, DE_SIZE_16,  0x0104);    // version
253         }
254         de_pop_sequence(attribute, avctpProtocol);
255     }
256     de_pop_sequence(service, attribute);
257 
258     // 0x0005 "Public Browse Group"
259     de_add_number(service,  DE_UINT, DE_SIZE_16, BLUETOOTH_ATTRIBUTE_BROWSE_GROUP_LIST); // public browse group
260     attribute = de_push_sequence(service);
261     {
262         de_add_number(attribute,  DE_UUID, DE_SIZE_16, BLUETOOTH_ATTRIBUTE_PUBLIC_BROWSE_ROOT);
263     }
264     de_pop_sequence(service, attribute);
265 
266     // 0x0009 "Bluetooth Profile Descriptor List"
267     de_add_number(service,  DE_UINT, DE_SIZE_16, BLUETOOTH_ATTRIBUTE_BLUETOOTH_PROFILE_DESCRIPTOR_LIST);
268     attribute = de_push_sequence(service);
269     {
270         uint8_t *avrcProfile = de_push_sequence(attribute);
271         {
272             de_add_number(avrcProfile,  DE_UUID, DE_SIZE_16, BLUETOOTH_SERVICE_CLASS_AV_REMOTE_CONTROL);
273             de_add_number(avrcProfile,  DE_UINT, DE_SIZE_16, 0x0106);
274         }
275         de_pop_sequence(attribute, avrcProfile);
276     }
277     de_pop_sequence(service, attribute);
278 
279     // 0x000d "Additional Bluetooth Profile Descriptor List"
280     if (browsing){
281         de_add_number(service,  DE_UINT, DE_SIZE_16, BLUETOOTH_ATTRIBUTE_ADDITIONAL_PROTOCOL_DESCRIPTOR_LISTS);
282         attribute = de_push_sequence(service);
283         {
284             uint8_t * des = de_push_sequence(attribute);
285             {
286                 uint8_t* browsing_l2cpProtocol = de_push_sequence(des);
287                 {
288                     de_add_number(browsing_l2cpProtocol,  DE_UUID, DE_SIZE_16, BLUETOOTH_PROTOCOL_L2CAP);
289                     de_add_number(browsing_l2cpProtocol,  DE_UINT, DE_SIZE_16, BLUETOOTH_PSM_AVCTP_BROWSING);
290                 }
291                 de_pop_sequence(des, browsing_l2cpProtocol);
292 
293                 uint8_t* browsing_avctpProtocol = de_push_sequence(des);
294                 {
295                     de_add_number(browsing_avctpProtocol,  DE_UUID, DE_SIZE_16, BLUETOOTH_PROTOCOL_AVCTP);  // browsing_avctpProtocol_service
296                     de_add_number(browsing_avctpProtocol,  DE_UINT, DE_SIZE_16, 0x0104);                   // version
297                 }
298                 de_pop_sequence(des, browsing_avctpProtocol);
299             }
300             de_pop_sequence(attribute, des);
301         }
302         de_pop_sequence(service, attribute);
303     }
304 
305 
306     // 0x0100 "Service Name"
307     de_add_number(service,  DE_UINT, DE_SIZE_16, 0x0100);
308     if (service_name){
309         de_add_data(service,  DE_STRING, strlen(service_name), (uint8_t *) service_name);
310     } else {
311         if (controller){
312             de_add_data(service, DE_STRING, strlen(avrcp_default_controller_service_name), (uint8_t *) avrcp_default_controller_service_name);
313         } else {
314             de_add_data(service, DE_STRING, strlen(avrcp_defaul_target_service_name), (uint8_t *) avrcp_defaul_target_service_name);
315         }
316     }
317 
318     // 0x0100 "Provider Name"
319     de_add_number(service,  DE_UINT, DE_SIZE_16, 0x0102);
320     if (service_provider_name){
321         de_add_data(service,  DE_STRING, strlen(service_provider_name), (uint8_t *) service_provider_name);
322     } else {
323         if (controller){
324             de_add_data(service, DE_STRING, strlen(avrcp_default_controller_service_provider_name), (uint8_t *) avrcp_default_controller_service_provider_name);
325         } else {
326             de_add_data(service, DE_STRING, strlen(avrcp_default_target_service_provider_name), (uint8_t *) avrcp_default_target_service_provider_name);
327         }
328     }
329 
330     // 0x0311 "Supported Features"
331     de_add_number(service, DE_UINT, DE_SIZE_16, 0x0311);
332     de_add_number(service, DE_UINT, DE_SIZE_16, supported_features);
333 }
334 
335 uint16_t avctp_get_num_bytes_for_header(avctp_packet_type_t avctp_packet_type) {
336     switch (avctp_packet_type){
337         case AVCTP_SINGLE_PACKET:
338             // AVCTP message: transport header (1), pid (2)
339             return 3;
340         case AVCTP_START_PACKET:
341             // AVCTP message: transport header (1), num_packets (1), pid (2)
342             return 4;
343         default:
344             // AVCTP message: transport header (1)
345             return 1;
346     }
347 }
348 
349 uint16_t avrcp_get_num_bytes_for_header(avrcp_command_opcode_t command_opcode, avctp_packet_type_t avctp_packet_type) {
350     switch (avctp_packet_type){
351         case AVCTP_SINGLE_PACKET:
352         case AVCTP_START_PACKET:
353             break;
354         default:
355             return 0;
356     }
357 
358     uint16_t offset = 3; // AVRCP message: cmd type (1), subunit (1), opcode (1)
359     switch (command_opcode){
360         case AVRCP_CMD_OPCODE_VENDOR_DEPENDENT:
361             offset += 7; // AVRCP message:  company (3), pdu id(1), AVRCP packet type (1), param_len (2)
362             break;
363         case AVRCP_CMD_OPCODE_PASS_THROUGH:
364             offset += 3;  // AVRCP message: operation id (1), param_len (2)
365             break;
366         default:
367             break;
368     }
369     return offset;
370 }
371 
372 static uint16_t avrcp_get_num_free_bytes_for_payload(uint16_t l2cap_mtu, avrcp_command_opcode_t command_opcode, avctp_packet_type_t avctp_packet_type){
373     uint16_t max_frame_size = btstack_min(l2cap_mtu, AVRCP_MAX_AV_C_MESSAGE_FRAME_SIZE);
374     uint16_t payload_offset = avctp_get_num_bytes_for_header(avctp_packet_type) +
375                               avrcp_get_num_bytes_for_header(command_opcode, avctp_packet_type);
376 
377     btstack_assert(max_frame_size >= payload_offset);
378     return (max_frame_size - payload_offset);
379 }
380 
381 
382 avctp_packet_type_t avctp_get_packet_type(avrcp_connection_t * connection, uint16_t * max_payload_size){
383     if (connection->data_offset == 0){
384         uint16_t max_payload_size_for_single_packet = avrcp_get_num_free_bytes_for_payload(connection->l2cap_mtu,
385                                                                  connection->command_opcode,
386                                                                  AVCTP_SINGLE_PACKET);
387         if (max_payload_size_for_single_packet >= connection->data_len){
388             *max_payload_size = max_payload_size_for_single_packet;
389             return AVCTP_SINGLE_PACKET;
390         } else {
391             uint16_t max_payload_size_for_start_packet = max_payload_size_for_single_packet - 1;
392             *max_payload_size = max_payload_size_for_start_packet;
393             return AVCTP_START_PACKET;
394         }
395     } else {
396         // both packet types have the same single byte AVCTP header
397         *max_payload_size = avrcp_get_num_free_bytes_for_payload(connection->l2cap_mtu,
398                                                                  connection->command_opcode,
399                                                                  AVCTP_CONTINUE_PACKET);
400         if ((connection->data_len - connection->data_offset) > *max_payload_size){
401             return AVCTP_CONTINUE_PACKET;
402         } else {
403             return AVCTP_END_PACKET;
404         }
405     }
406 }
407 
408 avrcp_packet_type_t avrcp_get_packet_type(avrcp_connection_t * connection){
409     switch (connection->avctp_packet_type) {
410         case AVCTP_SINGLE_PACKET:
411         case AVCTP_START_PACKET:
412             break;
413         default:
414             return connection->avrcp_packet_type;
415     }
416 
417     if (connection->data_offset == 0){
418         if (AVRCP_MAX_AV_C_MESSAGE_FRAME_SIZE >= connection->data_len){
419             return AVRCP_SINGLE_PACKET;
420         } else {
421             return AVRCP_START_PACKET;
422         }
423     } else {
424         if ((connection->data_len - connection->data_offset) > AVRCP_MAX_AV_C_MESSAGE_FRAME_SIZE){
425             return AVRCP_CONTINUE_PACKET;
426         } else {
427             return AVRCP_END_PACKET;
428         }
429     }
430 }
431 
432 avrcp_connection_t * avrcp_get_connection_for_bd_addr_for_role(avrcp_role_t role, bd_addr_t addr){
433     btstack_linked_list_iterator_t it;
434     btstack_linked_list_iterator_init(&it, (btstack_linked_list_t *) &avrcp_connections);
435     while (btstack_linked_list_iterator_has_next(&it)){
436         avrcp_connection_t * connection = (avrcp_connection_t *)btstack_linked_list_iterator_next(&it);
437         if (connection->role != role) continue;
438         if (memcmp(addr, connection->remote_addr, 6) != 0) continue;
439         return connection;
440     }
441     return NULL;
442 }
443 
444 avrcp_connection_t * avrcp_get_connection_for_l2cap_signaling_cid_for_role(avrcp_role_t role, uint16_t l2cap_cid){
445     btstack_linked_list_iterator_t it;
446     btstack_linked_list_iterator_init(&it, (btstack_linked_list_t *) &avrcp_connections);
447     while (btstack_linked_list_iterator_has_next(&it)){
448         avrcp_connection_t * connection = (avrcp_connection_t *)btstack_linked_list_iterator_next(&it);
449         if (connection->role != role) continue;
450         if (connection->l2cap_signaling_cid != l2cap_cid) continue;
451         return connection;
452     }
453     return NULL;
454 }
455 
456 avrcp_connection_t * avrcp_get_connection_for_avrcp_cid_for_role(avrcp_role_t role, uint16_t avrcp_cid){
457     btstack_linked_list_iterator_t it;
458     btstack_linked_list_iterator_init(&it, (btstack_linked_list_t *) &avrcp_connections);
459     while (btstack_linked_list_iterator_has_next(&it)){
460         avrcp_connection_t * connection = (avrcp_connection_t *)btstack_linked_list_iterator_next(&it);
461         if (connection->role != role) continue;
462         if (connection->avrcp_cid != avrcp_cid) continue;
463         return connection;
464     }
465     return NULL;
466 }
467 
468 avrcp_connection_t * avrcp_get_connection_for_browsing_cid_for_role(avrcp_role_t role, uint16_t browsing_cid){
469     btstack_linked_list_iterator_t it;
470     btstack_linked_list_iterator_init(&it, (btstack_linked_list_t *) &avrcp_connections);
471     while (btstack_linked_list_iterator_has_next(&it)){
472         avrcp_connection_t * connection = (avrcp_connection_t *)btstack_linked_list_iterator_next(&it);
473         if (connection->role != role) continue;
474         if (connection->avrcp_browsing_cid != browsing_cid) continue;
475         return connection;
476     }
477     return NULL;
478 }
479 
480 avrcp_connection_t * avrcp_get_connection_for_browsing_l2cap_cid_for_role(avrcp_role_t role, uint16_t browsing_l2cap_cid){
481     btstack_linked_list_iterator_t it;
482     btstack_linked_list_iterator_init(&it, (btstack_linked_list_t *) &avrcp_connections);
483     while (btstack_linked_list_iterator_has_next(&it)){
484         avrcp_connection_t * connection = (avrcp_connection_t *)btstack_linked_list_iterator_next(&it);
485         if (connection->role != role) continue;
486         if (connection->browsing_connection &&  (connection->browsing_connection->l2cap_browsing_cid != browsing_l2cap_cid)) continue;
487         return connection;
488     }
489     return NULL;
490 }
491 
492 avrcp_browsing_connection_t * avrcp_get_browsing_connection_for_l2cap_cid_for_role(avrcp_role_t role, uint16_t l2cap_cid){
493     btstack_linked_list_iterator_t it;
494     btstack_linked_list_iterator_init(&it, (btstack_linked_list_t *) &avrcp_connections);
495     while (btstack_linked_list_iterator_has_next(&it)){
496         avrcp_connection_t * connection = (avrcp_connection_t *)btstack_linked_list_iterator_next(&it);
497         if (connection->role != role) continue;
498         if (connection->browsing_connection && (connection->browsing_connection->l2cap_browsing_cid != l2cap_cid)) continue;
499         return connection->browsing_connection;
500     }
501     return NULL;
502 }
503 
504 void avrcp_request_can_send_now(avrcp_connection_t * connection, uint16_t l2cap_cid){
505     connection->wait_to_send = true;
506     l2cap_request_can_send_now_event(l2cap_cid);
507 }
508 
509 uint16_t avrcp_get_next_cid(avrcp_role_t role){
510     do {
511         if (avrcp_cid_counter == 0xffff) {
512             avrcp_cid_counter = 1;
513         } else {
514             avrcp_cid_counter++;
515         }
516     } while (avrcp_get_connection_for_avrcp_cid_for_role(role, avrcp_cid_counter) !=  NULL) ;
517     return avrcp_cid_counter;
518 }
519 
520 static avrcp_connection_t * avrcp_create_connection(avrcp_role_t role, bd_addr_t remote_addr){
521     avrcp_connection_t * connection = btstack_memory_avrcp_connection_get();
522     if (!connection){
523         log_error("Not enough memory to create connection for role %d", role);
524         return NULL;
525     }
526 
527     connection->state = AVCTP_CONNECTION_IDLE;
528     connection->role = role;
529 
530     connection->transaction_id = 0xFF;
531     connection->transaction_id_counter = 0;
532 
533     connection->controller_max_num_fragments = 0xFF;
534 
535     // setup default unit / subunit info
536     connection->company_id = 0xffffff;
537     connection->target_unit_type = AVRCP_SUBUNIT_TYPE_PANEL;
538     connection->target_subunit_info_data_size = sizeof(avrcp_default_subunit_info);
539     connection->target_subunit_info_data = avrcp_default_subunit_info;
540 
541     log_info("avrcp_create_connection, role %d", role);
542     (void)memcpy(connection->remote_addr, remote_addr, 6);
543     btstack_linked_list_add(&avrcp_connections, (btstack_linked_item_t *) connection);
544     return connection;
545 }
546 
547 static void avrcp_finalize_connection(avrcp_connection_t * connection){
548     btstack_run_loop_remove_timer(&connection->retry_timer);
549     btstack_linked_list_remove(&avrcp_connections, (btstack_linked_item_t*) connection);
550     btstack_memory_avrcp_connection_free(connection);
551 }
552 
553 static void avrcp_emit_connection_established(uint16_t avrcp_cid, bd_addr_t addr, hci_con_handle_t con_handle, uint8_t status){
554     btstack_assert(avrcp_callback != NULL);
555 
556     uint8_t event[14];
557     int pos = 0;
558     event[pos++] = HCI_EVENT_AVRCP_META;
559     event[pos++] = sizeof(event) - 2;
560     event[pos++] = AVRCP_SUBEVENT_CONNECTION_ESTABLISHED;
561     event[pos++] = status;
562     little_endian_store_16(event, pos, avrcp_cid);
563     pos += 2;
564     reverse_bd_addr(addr,&event[pos]);
565     pos += 6;
566     little_endian_store_16(event, pos, con_handle);
567     pos += 2;
568     (*avrcp_callback)(HCI_EVENT_PACKET, 0, event, sizeof(event));
569 }
570 
571 static void avrcp_emit_connection_closed(uint16_t avrcp_cid){
572     btstack_assert(avrcp_callback != NULL);
573 
574     uint8_t event[5];
575     int pos = 0;
576     event[pos++] = HCI_EVENT_AVRCP_META;
577     event[pos++] = sizeof(event) - 2;
578     event[pos++] = AVRCP_SUBEVENT_CONNECTION_RELEASED;
579     little_endian_store_16(event, pos, avrcp_cid);
580     pos += 2;
581     (*avrcp_callback)(HCI_EVENT_PACKET, 0, event, sizeof(event));
582 }
583 
584 uint16_t avrcp_sdp_query_browsing_l2cap_psm(void){
585     return avrcp_sdp_query_context.browsing_l2cap_psm;
586 }
587 
588 void avrcp_handle_sdp_client_query_attribute_value(uint8_t *packet){
589     des_iterator_t des_list_it;
590     des_iterator_t prot_it;
591 
592     // Handle new SDP record
593     if (sdp_event_query_attribute_byte_get_record_id(packet) != avrcp_sdp_query_context.record_id) {
594         avrcp_sdp_query_context.record_id = sdp_event_query_attribute_byte_get_record_id(packet);
595         avrcp_sdp_query_context.parse_sdp_record = 0;
596         // log_info("SDP Record: Nr: %d", record_id);
597     }
598 
599     if (sdp_event_query_attribute_byte_get_attribute_length(packet) <= avrcp_sdp_query_attribute_value_buffer_size) {
600         avrcp_sdp_query_attribute_value[sdp_event_query_attribute_byte_get_data_offset(packet)] = sdp_event_query_attribute_byte_get_data(packet);
601 
602         if ((uint16_t)(sdp_event_query_attribute_byte_get_data_offset(packet)+1) == sdp_event_query_attribute_byte_get_attribute_length(packet)) {
603             switch(sdp_event_query_attribute_byte_get_attribute_id(packet)) {
604                 case BLUETOOTH_ATTRIBUTE_SERVICE_CLASS_ID_LIST:
605                     if (de_get_element_type(avrcp_sdp_query_attribute_value) != DE_DES) break;
606                     for (des_iterator_init(&des_list_it, avrcp_sdp_query_attribute_value); des_iterator_has_more(&des_list_it); des_iterator_next(&des_list_it)) {
607                         uint8_t * element = des_iterator_get_element(&des_list_it);
608                         if (de_get_element_type(element) != DE_UUID) continue;
609                         uint32_t uuid = de_get_uuid32(element);
610                         switch (uuid){
611                             case BLUETOOTH_SERVICE_CLASS_AV_REMOTE_CONTROL_TARGET:
612                             case BLUETOOTH_SERVICE_CLASS_AV_REMOTE_CONTROL:
613                             case BLUETOOTH_SERVICE_CLASS_AV_REMOTE_CONTROL_CONTROLLER:
614                                 avrcp_sdp_query_context.parse_sdp_record = 1;
615                                 break;
616                             default:
617                                 break;
618                         }
619                     }
620                     break;
621 
622                 case BLUETOOTH_ATTRIBUTE_PROTOCOL_DESCRIPTOR_LIST: {
623                     if (!avrcp_sdp_query_context.parse_sdp_record) break;
624                     // log_info("SDP Attribute: 0x%04x", sdp_event_query_attribute_byte_get_attribute_id(packet));
625                     for (des_iterator_init(&des_list_it, avrcp_sdp_query_attribute_value); des_iterator_has_more(&des_list_it); des_iterator_next(&des_list_it)) {
626                         uint8_t       *des_element;
627                         uint8_t       *element;
628                         uint32_t       uuid;
629 
630                         if (des_iterator_get_type(&des_list_it) != DE_DES) continue;
631 
632                         des_element = des_iterator_get_element(&des_list_it);
633                         des_iterator_init(&prot_it, des_element);
634                         element = des_iterator_get_element(&prot_it);
635 
636                         if (de_get_element_type(element) != DE_UUID) continue;
637 
638                         uuid = de_get_uuid32(element);
639                         des_iterator_next(&prot_it);
640                         switch (uuid){
641                             case BLUETOOTH_PROTOCOL_L2CAP:
642                                 if (!des_iterator_has_more(&prot_it)) continue;
643                                 de_element_get_uint16(des_iterator_get_element(&prot_it), &avrcp_sdp_query_context.avrcp_l2cap_psm);
644                                 break;
645                             case BLUETOOTH_PROTOCOL_AVCTP:
646                                 if (!des_iterator_has_more(&prot_it)) continue;
647                                 de_element_get_uint16(des_iterator_get_element(&prot_it), &avrcp_sdp_query_context.avrcp_version);
648                                 break;
649                             default:
650                                 break;
651                         }
652                     }
653                 }
654                     break;
655                 case BLUETOOTH_ATTRIBUTE_ADDITIONAL_PROTOCOL_DESCRIPTOR_LISTS: {
656                     // log_info("SDP Attribute: 0x%04x", sdp_event_query_attribute_byte_get_attribute_id(packet));
657                     if (!avrcp_sdp_query_context.parse_sdp_record) break;
658                     if (de_get_element_type(avrcp_sdp_query_attribute_value) != DE_DES) break;
659 
660                     des_iterator_t des_list_0_it;
661                     uint8_t       *element_0;
662 
663                     des_iterator_init(&des_list_0_it, avrcp_sdp_query_attribute_value);
664                     element_0 = des_iterator_get_element(&des_list_0_it);
665 
666                     for (des_iterator_init(&des_list_it, element_0); des_iterator_has_more(&des_list_it); des_iterator_next(&des_list_it)) {
667                         uint8_t       *des_element;
668                         uint8_t       *element;
669                         uint32_t       uuid;
670 
671                         if (des_iterator_get_type(&des_list_it) != DE_DES) continue;
672 
673                         des_element = des_iterator_get_element(&des_list_it);
674                         des_iterator_init(&prot_it, des_element);
675                         element = des_iterator_get_element(&prot_it);
676 
677                         if (de_get_element_type(element) != DE_UUID) continue;
678 
679                         uuid = de_get_uuid32(element);
680                         des_iterator_next(&prot_it);
681                         switch (uuid){
682                             case BLUETOOTH_PROTOCOL_L2CAP:
683                                 if (!des_iterator_has_more(&prot_it)) continue;
684                                 de_element_get_uint16(des_iterator_get_element(&prot_it), &avrcp_sdp_query_context.browsing_l2cap_psm);
685                                 break;
686                             case BLUETOOTH_PROTOCOL_AVCTP:
687                                 if (!des_iterator_has_more(&prot_it)) continue;
688                                 de_element_get_uint16(des_iterator_get_element(&prot_it), &avrcp_sdp_query_context.browsing_version);
689                                 break;
690                             default:
691                                 break;
692                         }
693                     }
694                 }
695                     break;
696                 default:
697                     break;
698             }
699         }
700     } else {
701         log_error("SDP attribute value buffer size exceeded: available %d, required %d", avrcp_sdp_query_attribute_value_buffer_size, sdp_event_query_attribute_byte_get_attribute_length(packet));
702     }
703 }
704 
705 static void avrcp_handle_sdp_query_failed(avrcp_connection_t * connection, uint8_t status){
706     if (connection == NULL) return;
707     log_info("AVRCP: SDP query failed with status 0x%02x.", status);
708     avrcp_emit_connection_established(connection->avrcp_cid, connection->remote_addr, connection->con_handle, status);
709     avrcp_finalize_connection(connection);
710 }
711 
712 static void avrcp_handle_sdp_query_succeeded(avrcp_connection_t * connection){
713     if (connection == NULL) return;
714     connection->state = AVCTP_CONNECTION_W4_L2CAP_CONNECTED;
715     connection->avrcp_l2cap_psm = avrcp_sdp_query_context.avrcp_l2cap_psm;
716     connection->browsing_version = avrcp_sdp_query_context.browsing_version;
717     connection->browsing_l2cap_psm = avrcp_sdp_query_context.browsing_l2cap_psm;
718 }
719 
720 static void avrcp_handle_sdp_client_query_result(uint8_t packet_type, uint16_t channel, uint8_t *packet, uint16_t size){
721     UNUSED(packet_type);
722     UNUSED(channel);
723     UNUSED(size);
724 
725     bool state_ok = true;
726     avrcp_connection_t * avrcp_target_connection = avrcp_get_connection_for_avrcp_cid_for_role(AVRCP_TARGET, avrcp_sdp_query_context.avrcp_cid);
727     if (!avrcp_target_connection || avrcp_target_connection->state != AVCTP_CONNECTION_W4_SDP_QUERY_COMPLETE) {
728         state_ok = false;
729     }
730     avrcp_connection_t * avrcp_controller_connection = avrcp_get_connection_for_avrcp_cid_for_role(AVRCP_CONTROLLER, avrcp_sdp_query_context.avrcp_cid);
731     if (!avrcp_controller_connection || avrcp_controller_connection->state != AVCTP_CONNECTION_W4_SDP_QUERY_COMPLETE) {
732         state_ok = false;
733     }
734     if (!state_ok){
735         // something wrong, nevertheless, start next sdp query if this one is complete
736         if (hci_event_packet_get_type(packet) == SDP_EVENT_QUERY_COMPLETE){
737             (void) sdp_client_register_query_callback(&avrcp_sdp_query_registration);
738         }
739         return;
740     }
741 
742     uint8_t status;
743 
744     switch (hci_event_packet_get_type(packet)){
745         case SDP_EVENT_QUERY_ATTRIBUTE_VALUE:
746             avrcp_handle_sdp_client_query_attribute_value(packet);
747             return;
748 
749         case SDP_EVENT_QUERY_COMPLETE:
750             status = sdp_event_query_complete_get_status(packet);
751 
752             if (status != ERROR_CODE_SUCCESS){
753                 avrcp_handle_sdp_query_failed(avrcp_controller_connection, status);
754                 avrcp_handle_sdp_query_failed(avrcp_target_connection, status);
755                 break;
756             }
757 
758             if (!avrcp_sdp_query_context.avrcp_l2cap_psm){
759                 avrcp_handle_sdp_query_failed(avrcp_controller_connection, SDP_SERVICE_NOT_FOUND);
760                 avrcp_handle_sdp_query_failed(avrcp_target_connection, SDP_SERVICE_NOT_FOUND);
761                 break;
762             }
763 
764             avrcp_handle_sdp_query_succeeded(avrcp_controller_connection);
765             avrcp_handle_sdp_query_succeeded(avrcp_target_connection);
766 
767             l2cap_create_channel(&avrcp_packet_handler, avrcp_target_connection->remote_addr, avrcp_sdp_query_context.avrcp_l2cap_psm, l2cap_max_mtu(), NULL);
768             break;
769 
770         default:
771             return;
772     }
773 
774     // register the SDP Query request to check if there is another connection waiting for the query
775     // ignore ERROR_CODE_COMMAND_DISALLOWED because in that case, we already have requested an SDP callback
776     (void) sdp_client_register_query_callback(&avrcp_sdp_query_registration);
777 }
778 
779 
780 static avrcp_connection_t * avrcp_handle_incoming_connection_for_role(avrcp_role_t role, avrcp_connection_t * connection, bd_addr_t event_addr, hci_con_handle_t con_handle, uint16_t local_cid, uint16_t avrcp_cid){
781     if (connection == NULL){
782         connection = avrcp_create_connection(role, event_addr);
783     }
784     if (connection) {
785         connection->state = AVCTP_CONNECTION_W4_L2CAP_CONNECTED;
786         connection->l2cap_signaling_cid = local_cid;
787         connection->avrcp_cid = avrcp_cid;
788         connection->con_handle = con_handle;
789         btstack_run_loop_remove_timer(&connection->retry_timer);
790     }
791     return connection;
792 }
793 
794 static void avrcp_handle_open_connection(avrcp_connection_t * connection, hci_con_handle_t con_handle, uint16_t local_cid, uint16_t l2cap_mtu){
795     connection->l2cap_signaling_cid = local_cid;
796     connection->l2cap_mtu = l2cap_mtu;
797     connection->con_handle = con_handle;
798     connection->incoming_declined = false;
799     connection->target_song_length_ms = 0xFFFFFFFF;
800     connection->target_song_position_ms = 0xFFFFFFFF;
801     memset(connection->target_track_id, 0xFF, 8);
802     connection->target_track_selected = false;
803     connection->target_playback_status = AVRCP_PLAYBACK_STATUS_STOPPED;
804     connection->state = AVCTP_CONNECTION_OPENED;
805 
806     log_info("L2CAP_EVENT_CHANNEL_OPENED avrcp_cid 0x%02x, l2cap_signaling_cid 0x%02x, role %d, state %d", connection->avrcp_cid, connection->l2cap_signaling_cid, connection->role, connection->state);
807 }
808 
809 static void avrcp_retry_timer_timeout_handler(btstack_timer_source_t * timer){
810     uint16_t avrcp_cid = (uint16_t)(uintptr_t) btstack_run_loop_get_timer_context(timer);
811     avrcp_connection_t * connection_controller = avrcp_get_connection_for_avrcp_cid_for_role(AVRCP_CONTROLLER, avrcp_cid);
812     if (connection_controller == NULL) return;
813     avrcp_connection_t * connection_target = avrcp_get_connection_for_avrcp_cid_for_role(AVRCP_TARGET, avrcp_cid);
814     if (connection_target == NULL) return;
815 
816     if (connection_controller->state == AVCTP_CONNECTION_W2_L2CAP_RETRY){
817         connection_controller->state = AVCTP_CONNECTION_W4_L2CAP_CONNECTED;
818         connection_target->state = AVCTP_CONNECTION_W4_L2CAP_CONNECTED;
819         l2cap_create_channel(&avrcp_packet_handler, connection_controller->remote_addr, connection_controller->avrcp_l2cap_psm, l2cap_max_mtu(), NULL);
820     }
821 }
822 
823 static void avrcp_retry_timer_start(avrcp_connection_t * connection){
824     btstack_run_loop_set_timer_handler(&connection->retry_timer, avrcp_retry_timer_timeout_handler);
825     btstack_run_loop_set_timer_context(&connection->retry_timer, (void *)(uintptr_t)connection->avrcp_cid);
826 
827     // add some jitter/randomness to reconnect delay
828     uint32_t timeout = 100 + (btstack_run_loop_get_time_ms() & 0x7F);
829     btstack_run_loop_set_timer(&connection->retry_timer, timeout);
830 
831     btstack_run_loop_add_timer(&connection->retry_timer);
832 }
833 
834 static avrcp_frame_type_t avrcp_get_frame_type(uint8_t header){
835     return (avrcp_frame_type_t)((header & 0x02) >> 1);
836 }
837 
838 static void avrcp_packet_handler(uint8_t packet_type, uint16_t channel, uint8_t *packet, uint16_t size){
839     UNUSED(channel);
840     UNUSED(size);
841     bd_addr_t event_addr;
842     uint16_t local_cid;
843     uint16_t l2cap_mtu;
844     uint8_t  status;
845     bool decline_connection;
846     bool outoing_active;
847     hci_con_handle_t con_handle;
848 
849     avrcp_connection_t * connection_controller;
850     avrcp_connection_t * connection_target;
851     bool can_send;
852 
853     switch (packet_type) {
854         case HCI_EVENT_PACKET:
855             switch (hci_event_packet_get_type(packet)) {
856 
857                 case L2CAP_EVENT_INCOMING_CONNECTION:
858                     btstack_assert(avrcp_controller_packet_handler != NULL);
859                     btstack_assert(avrcp_target_packet_handler != NULL);
860 
861                     l2cap_event_incoming_connection_get_address(packet, event_addr);
862                     local_cid = l2cap_event_incoming_connection_get_local_cid(packet);
863                     con_handle = l2cap_event_incoming_connection_get_handle(packet);
864 
865                     outoing_active = false;
866                     connection_target = avrcp_get_connection_for_bd_addr_for_role(AVRCP_TARGET, event_addr);
867                     if (connection_target != NULL){
868                         if (connection_target->state == AVCTP_CONNECTION_W4_L2CAP_CONNECTED){
869                             outoing_active = true;
870                             connection_target->incoming_declined = true;
871                         }
872                     }
873 
874                     connection_controller = avrcp_get_connection_for_bd_addr_for_role(AVRCP_CONTROLLER, event_addr);
875                     if (connection_controller != NULL){
876                         if (connection_controller->state == AVCTP_CONNECTION_W4_L2CAP_CONNECTED) {
877                             outoing_active = true;
878                             connection_controller->incoming_declined = true;
879                         }
880                     }
881 
882                     decline_connection = outoing_active;
883                     if (decline_connection == false){
884                         uint16_t avrcp_cid;
885                         if ((connection_controller == NULL) || (connection_target == NULL)){
886                             avrcp_cid = avrcp_get_next_cid(AVRCP_CONTROLLER);
887                         } else {
888                             avrcp_cid = connection_controller->avrcp_cid;
889                         }
890                         // create two connection objects (both)
891                         connection_target     = avrcp_handle_incoming_connection_for_role(AVRCP_TARGET, connection_target, event_addr, con_handle, local_cid, avrcp_cid);
892                         connection_controller = avrcp_handle_incoming_connection_for_role(AVRCP_CONTROLLER, connection_controller, event_addr, con_handle, local_cid, avrcp_cid);
893                         if ((connection_target == NULL) || (connection_controller == NULL)){
894                             decline_connection = true;
895                             if (connection_target) {
896                                 avrcp_finalize_connection(connection_target);
897                             }
898                             if (connection_controller) {
899                                 avrcp_finalize_connection(connection_controller);
900                             }
901                         }
902                     }
903                     if (decline_connection){
904                         l2cap_decline_connection(local_cid);
905                     } else {
906                         log_info("AVRCP: L2CAP_EVENT_INCOMING_CONNECTION local cid 0x%02x, state %d", local_cid, connection_controller->state);
907                         l2cap_accept_connection(local_cid);
908                     }
909                     break;
910 
911                 case L2CAP_EVENT_CHANNEL_OPENED:
912                     l2cap_event_channel_opened_get_address(packet, event_addr);
913                     status = l2cap_event_channel_opened_get_status(packet);
914                     local_cid = l2cap_event_channel_opened_get_local_cid(packet);
915                     l2cap_mtu = l2cap_event_channel_opened_get_remote_mtu(packet);
916                     con_handle = l2cap_event_channel_opened_get_handle(packet);
917 
918                     connection_controller = avrcp_get_connection_for_bd_addr_for_role(AVRCP_CONTROLLER, event_addr);
919                     connection_target = avrcp_get_connection_for_bd_addr_for_role(AVRCP_TARGET, event_addr);
920 
921                     // incoming: structs are already created in L2CAP_EVENT_INCOMING_CONNECTION
922                     // outgoing: structs are cteated in avrcp_connect()
923                     if ((connection_controller == NULL) || (connection_target == NULL)) {
924                         break;
925                     }
926 
927                     switch (status){
928                         case ERROR_CODE_SUCCESS:
929                             avrcp_handle_open_connection(connection_target, con_handle, local_cid, l2cap_mtu);
930                             avrcp_handle_open_connection(connection_controller, con_handle, local_cid, l2cap_mtu);
931                             avrcp_emit_connection_established(connection_controller->avrcp_cid, event_addr, con_handle, status);
932                             return;
933                         case L2CAP_CONNECTION_RESPONSE_RESULT_REFUSED_RESOURCES:
934                             if (connection_controller->incoming_declined == true){
935                                 log_info("Incoming connection was declined, and the outgoing failed");
936                                 connection_controller->state = AVCTP_CONNECTION_W2_L2CAP_RETRY;
937                                 connection_controller->incoming_declined = false;
938                                 connection_target->state = AVCTP_CONNECTION_W2_L2CAP_RETRY;
939                                 connection_target->incoming_declined = false;
940                                 avrcp_retry_timer_start(connection_controller);
941                                 return;
942                             }
943                             break;
944                         default:
945                             break;
946                     }
947                     log_info("L2CAP connection to connection %s failed. status code 0x%02x", bd_addr_to_str(event_addr), status);
948                     avrcp_emit_connection_established(connection_controller->avrcp_cid, event_addr, con_handle, status);
949                     avrcp_finalize_connection(connection_controller);
950                     avrcp_finalize_connection(connection_target);
951 
952                     break;
953 
954                 case L2CAP_EVENT_CHANNEL_CLOSED:
955                     local_cid = l2cap_event_channel_closed_get_local_cid(packet);
956 
957                     connection_controller = avrcp_get_connection_for_l2cap_signaling_cid_for_role(AVRCP_CONTROLLER, local_cid);
958                     connection_target = avrcp_get_connection_for_l2cap_signaling_cid_for_role(AVRCP_TARGET, local_cid);
959                     if ((connection_controller == NULL) || (connection_target == NULL)) {
960                         break;
961                     }
962                     avrcp_emit_connection_closed(connection_controller->avrcp_cid);
963                     avrcp_finalize_connection(connection_controller);
964                     avrcp_finalize_connection(connection_target);
965                     break;
966 
967                 case L2CAP_EVENT_CAN_SEND_NOW:
968                     local_cid = l2cap_event_can_send_now_get_local_cid(packet);
969                     can_send = true;
970 
971                     connection_target = avrcp_get_connection_for_l2cap_signaling_cid_for_role(AVRCP_TARGET, local_cid);
972                     if ((connection_target != NULL) && connection_target->wait_to_send){
973                         connection_target->wait_to_send = false;
974                         (*avrcp_target_packet_handler)(HCI_EVENT_PACKET, channel, packet, size);
975                         can_send = false;
976                     }
977 
978                     connection_controller = avrcp_get_connection_for_l2cap_signaling_cid_for_role(AVRCP_CONTROLLER, local_cid);
979                     if ((connection_controller != NULL) && connection_controller->wait_to_send){
980                         if (can_send){
981                             connection_controller->wait_to_send = false;
982                             (*avrcp_controller_packet_handler)(HCI_EVENT_PACKET, channel, packet, size);
983                         } else {
984                             l2cap_request_can_send_now_event(local_cid);
985                         }
986                     }
987                     break;
988 
989                 default:
990                     break;
991             }
992             break;
993 
994         case L2CAP_DATA_PACKET:
995             switch (avrcp_get_frame_type(packet[0])){
996                 case AVRCP_RESPONSE_FRAME:
997                     (*avrcp_controller_packet_handler)(packet_type, channel, packet, size);
998                     break;
999                 case AVRCP_COMMAND_FRAME:
1000                 default:    // make compiler happy
1001                     (*avrcp_target_packet_handler)(packet_type, channel, packet, size);
1002                     break;
1003             }
1004             break;
1005 
1006         default:
1007             break;
1008     }
1009 }
1010 
1011 uint8_t avrcp_disconnect(uint16_t avrcp_cid){
1012     avrcp_connection_t * connection_controller = avrcp_get_connection_for_avrcp_cid_for_role(AVRCP_CONTROLLER, avrcp_cid);
1013     if (!connection_controller){
1014         return ERROR_CODE_UNKNOWN_CONNECTION_IDENTIFIER;
1015     }
1016     avrcp_connection_t * connection_target = avrcp_get_connection_for_avrcp_cid_for_role(AVRCP_TARGET, avrcp_cid);
1017     if (!connection_target){
1018         return ERROR_CODE_UNKNOWN_CONNECTION_IDENTIFIER;
1019     }
1020     if (connection_controller->browsing_connection){
1021         l2cap_disconnect(connection_controller->browsing_connection->l2cap_browsing_cid);
1022     }
1023     l2cap_disconnect(connection_controller->l2cap_signaling_cid);
1024     return ERROR_CODE_SUCCESS;
1025 }
1026 
1027 static void avrcp_handle_start_sdp_client_query(void * context){
1028     UNUSED(context);
1029 
1030     btstack_linked_list_iterator_t it;
1031     btstack_linked_list_iterator_init(&it, &avrcp_connections);
1032     while (btstack_linked_list_iterator_has_next(&it)){
1033         avrcp_connection_t * connection = (avrcp_connection_t *)btstack_linked_list_iterator_next(&it);
1034 
1035         if (connection->state != AVCTP_CONNECTION_W2_SEND_SDP_QUERY) continue;
1036         connection->state = AVCTP_CONNECTION_W4_SDP_QUERY_COMPLETE;
1037 
1038         // prevent triggering SDP query twice (for each role once)
1039         avrcp_connection_t * connection_with_opposite_role;
1040         switch (connection->role){
1041             case AVRCP_CONTROLLER:
1042                 connection_with_opposite_role = avrcp_get_connection_for_avrcp_cid_for_role(AVRCP_TARGET, connection->avrcp_cid);
1043                 break;
1044             case AVRCP_TARGET:
1045                 connection_with_opposite_role = avrcp_get_connection_for_avrcp_cid_for_role(AVRCP_CONTROLLER, connection->avrcp_cid);
1046                 break;
1047             default:
1048                 btstack_assert(false);
1049                 return;
1050         }
1051         connection_with_opposite_role->state = AVCTP_CONNECTION_W4_SDP_QUERY_COMPLETE;
1052 
1053         avrcp_sdp_query_context.avrcp_l2cap_psm = 0;
1054         avrcp_sdp_query_context.avrcp_version  = 0;
1055         avrcp_sdp_query_context.avrcp_cid = connection->avrcp_cid;
1056         sdp_client_query_uuid16(&avrcp_handle_sdp_client_query_result, (uint8_t *) connection->remote_addr, BLUETOOTH_PROTOCOL_AVCTP);
1057         return;
1058     }
1059 }
1060 
1061 uint8_t avrcp_connect(bd_addr_t remote_addr, uint16_t * avrcp_cid){
1062     btstack_assert(avrcp_controller_packet_handler != NULL);
1063     btstack_assert(avrcp_target_packet_handler != NULL);
1064 
1065     avrcp_connection_t * connection_controller = avrcp_get_connection_for_bd_addr_for_role(AVRCP_CONTROLLER, remote_addr);
1066     if (connection_controller){
1067         return ERROR_CODE_COMMAND_DISALLOWED;
1068     }
1069     avrcp_connection_t * connection_target = avrcp_get_connection_for_bd_addr_for_role(AVRCP_TARGET, remote_addr);
1070     if (connection_target){
1071         return ERROR_CODE_COMMAND_DISALLOWED;
1072     }
1073 
1074     uint16_t cid = avrcp_get_next_cid(AVRCP_CONTROLLER);
1075 
1076     connection_controller = avrcp_create_connection(AVRCP_CONTROLLER, remote_addr);
1077     if (!connection_controller) return BTSTACK_MEMORY_ALLOC_FAILED;
1078 
1079     connection_target = avrcp_create_connection(AVRCP_TARGET, remote_addr);
1080     if (!connection_target){
1081         avrcp_finalize_connection(connection_controller);
1082         return BTSTACK_MEMORY_ALLOC_FAILED;
1083     }
1084 
1085     if (avrcp_cid != NULL){
1086         *avrcp_cid = cid;
1087     }
1088 
1089     connection_controller->state = AVCTP_CONNECTION_W2_SEND_SDP_QUERY;
1090     connection_controller->avrcp_cid = cid;
1091 
1092     connection_target->state     = AVCTP_CONNECTION_W2_SEND_SDP_QUERY;
1093     connection_target->avrcp_cid = cid;
1094 
1095     avrcp_sdp_query_registration.callback = &avrcp_handle_start_sdp_client_query;
1096     // ignore ERROR_CODE_COMMAND_DISALLOWED because in that case, we already have requested an SDP callback
1097     (void) sdp_client_register_query_callback(&avrcp_sdp_query_registration);
1098     return ERROR_CODE_SUCCESS;
1099 }
1100 
1101 void avrcp_init(void){
1102     avrcp_connections = NULL;
1103     if (avrcp_l2cap_service_registered) return;
1104 
1105     int status = l2cap_register_service(&avrcp_packet_handler, BLUETOOTH_PSM_AVCTP, 0xffff, gap_get_security_level());
1106     if (status != ERROR_CODE_SUCCESS) return;
1107     avrcp_l2cap_service_registered = true;
1108 }
1109 
1110 void avrcp_deinit(void){
1111     avrcp_l2cap_service_registered = false;
1112 
1113     avrcp_cid_counter = 0;
1114     avrcp_connections = NULL;
1115 
1116     avrcp_callback = NULL;
1117     avrcp_controller_packet_handler = NULL;
1118     avrcp_target_packet_handler = NULL;
1119 
1120     (void) memset(&avrcp_sdp_query_registration, 0, sizeof(avrcp_sdp_query_registration));
1121     (void) memset(&avrcp_sdp_query_context, 0, sizeof(avrcp_sdp_query_context_t));
1122     (void) memset(avrcp_sdp_query_attribute_value, 0, sizeof(avrcp_sdp_query_attribute_value));
1123 }
1124 
1125 void avrcp_register_controller_packet_handler(btstack_packet_handler_t callback){
1126     avrcp_controller_packet_handler = callback;
1127 }
1128 
1129 void avrcp_register_target_packet_handler(btstack_packet_handler_t callback){
1130     avrcp_target_packet_handler = callback;
1131 }
1132 
1133 void avrcp_register_packet_handler(btstack_packet_handler_t callback){
1134     btstack_assert(callback != NULL);
1135     avrcp_callback = callback;
1136 }
1137 
1138 #ifdef FUZZING_BUILD_MODE_UNSAFE_FOR_PRODUCTION
1139 #define FUZZ_CID 0x44
1140 #define FUZZ_CON_HANDLE 0x0001
1141 static bd_addr_t remote_addr = { 0x33, 0x33, 0x33, 0x33, 0x33, 0x33 };
1142 void avrcp_init_fuzz(void){
1143     // setup avrcp connections for cid
1144     avrcp_connection_t * connection_controller = avrcp_create_connection(AVRCP_CONTROLLER, remote_addr);
1145     avrcp_connection_t * connection_target     = avrcp_create_connection(AVRCP_TARGET, remote_addr);
1146     avrcp_handle_open_connection(connection_controller, FUZZ_CON_HANDLE, FUZZ_CID, 999);
1147     avrcp_handle_open_connection(connection_target, FUZZ_CON_HANDLE, FUZZ_CID, 999);
1148 }
1149 void avrcp_packet_handler_fuzz(uint8_t *packet, uint16_t size){
1150     avrcp_packet_handler(L2CAP_DATA_PACKET, FUZZ_CID, packet, size);
1151 }
1152 #endif