xref: /btstack/src/classic/avrcp.c (revision 7e7a3a6ea63904f47c98ff1f0b682c951b6d058c)
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     uint16_t cover_art_l2cap_psm;
65 } avrcp_sdp_query_context_t;
66 
67 static void avrcp_packet_handler(uint8_t packet_type, uint16_t channel, uint8_t *packet, uint16_t size);
68 static void avrcp_start_next_sdp_query(void);
69 
70 static const char * avrcp_default_controller_service_name = "BTstack AVRCP Controller Service";
71 static const char * avrcp_default_controller_service_provider_name = "BTstack AVRCP Controller Service Provider";
72 static const char * avrcp_defaul_target_service_name = "BTstack AVRCP Target Service";
73 static const char * avrcp_default_target_service_provider_name = "BTstack AVRCP Target Service Provider";
74 
75 static const char * avrcp_subunit_type_name[] = {
76         "MONITOR", "AUDIO", "PRINTER", "DISC", "TAPE_RECORDER_PLAYER", "TUNER",
77         "CA", "CAMERA", "RESERVED", "PANEL", "BULLETIN_BOARD", "CAMERA_STORAGE",
78         "VENDOR_UNIQUE", "RESERVED_FOR_ALL_SUBUNIT_TYPES",
79         "EXTENDED_TO_NEXT_BYTE", "UNIT", "ERROR"
80 };
81 
82 // default subunit info: single PANEL subunit
83 static const uint8_t avrcp_default_subunit_info[] = { AVRCP_SUBUNIT_TYPE_PANEL << 3};
84 
85 // globals
86 static bool avrcp_l2cap_service_registered = false;
87 
88 // connections
89 static uint16_t                 avrcp_cid_counter;
90 static btstack_linked_list_t    avrcp_connections;
91 
92 // higher layer callbacks
93 static btstack_packet_handler_t avrcp_callback;
94 static btstack_packet_handler_t avrcp_controller_packet_handler;
95 static btstack_packet_handler_t avrcp_target_packet_handler;
96 
97 // sdp query
98 static btstack_context_callback_registration_t avrcp_sdp_query_registration;
99 static avrcp_sdp_query_context_t               avrcp_sdp_query_context;
100 static uint8_t                                 avrcp_sdp_query_attribute_value[45];
101 static const unsigned int                      avrcp_sdp_query_attribute_value_buffer_size = sizeof(avrcp_sdp_query_attribute_value);
102 
103 static void (*avrcp_browsing_sdp_query_complete_handler)(avrcp_connection_t * connection, uint8_t status);
104 
105 
106 const char * avrcp_subunit2str(uint16_t index){
107     if (index <= 11) return avrcp_subunit_type_name[index];
108     if ((index >= 0x1C) && (index <= 0x1F)) return avrcp_subunit_type_name[index - 0x10];
109     return avrcp_subunit_type_name[16];
110 }
111 
112 static const char * avrcp_event_name[] = {
113     "ERROR", "PLAYBACK_STATUS_CHANGED",
114     "TRACK_CHANGED", "TRACK_REACHED_END", "TRACK_REACHED_START",
115     "PLAYBACK_POS_CHANGED", "BATT_STATUS_CHANGED", "SYSTEM_STATUS_CHANGED",
116     "PLAYER_APPLICATION_SETTING_CHANGED", "NOW_PLAYING_CONTENT_CHANGED",
117     "AVAILABLE_PLAYERS_CHANGED", "ADDRESSED_PLAYER_CHANGED", "UIDS_CHANGED", "VOLUME_CHANGED"
118 };
119 const char * avrcp_event2str(uint16_t index){
120     if (index <= 0x0d) return avrcp_event_name[index];
121     return avrcp_event_name[0];
122 }
123 
124 static const char * avrcp_operation_name[] = {
125     "SKIP", NULL, NULL, NULL, NULL,
126     "VOLUME_UP", "VOLUME_DOWN", "MUTE", "PLAY", "STOP", "PAUSE", NULL,
127     "REWIND", "FAST_FORWARD", NULL, "FORWARD", "BACKWARD" // 0x4C
128 };
129 
130 const char * avrcp_operation2str(uint8_t operation_id){
131     char * name = NULL;
132     if ((operation_id >= AVRCP_OPERATION_ID_SKIP) && (operation_id <= AVRCP_OPERATION_ID_BACKWARD)){
133         name = (char *)avrcp_operation_name[operation_id - AVRCP_OPERATION_ID_SKIP];
134     }
135     if (name == NULL){
136         static char buffer[13];
137         snprintf(buffer, sizeof(buffer), "Unknown 0x%02x", operation_id);
138         buffer[sizeof(buffer)-1] = 0;
139         return buffer;
140     } else {
141         return name;
142     }
143 }
144 
145 static const char * avrcp_media_attribute_id_name[] = {
146     "NONE", "TITLE", "ARTIST", "ALBUM", "TRACK", "TOTAL TRACKS", "GENRE", "SONG LENGTH"
147 };
148 const char * avrcp_attribute2str(uint8_t index){
149     if (index > 7){
150         index = 0;
151     }
152     return avrcp_media_attribute_id_name[0];
153 }
154 
155 static const char * avrcp_play_status_name[] = {
156     "STOPPED", "PLAYING", "PAUSED", "FORWARD SEEK", "REVERSE SEEK",
157     "ERROR" // 0xFF
158 };
159 const char * avrcp_play_status2str(uint8_t index){
160     if (index > 4){
161         index = 5;
162     }
163     return avrcp_play_status_name[index];
164 }
165 
166 static const char * avrcp_ctype_name[] = {
167     "CONTROL",
168     "STATUS",
169     "SPECIFIC_INQUIRY",
170     "NOTIFY",
171     "GENERAL_INQUIRY",
172     "RESERVED5",
173     "RESERVED6",
174     "RESERVED7",
175     "NOT IMPLEMENTED IN REMOTE",
176     "ACCEPTED BY REMOTE",
177     "REJECTED BY REMOTE",
178     "IN_TRANSITION",
179     "IMPLEMENTED_STABLE",
180     "CHANGED_STABLE",
181     "RESERVED",
182     "INTERIM"
183 };
184 static const uint16_t avrcp_ctype_name_num = 16;
185 
186 const char * avrcp_ctype2str(uint8_t index){
187     if (index < avrcp_ctype_name_num){
188         return avrcp_ctype_name[index];
189     }
190     return "NONE";
191 }
192 
193 static const char * avrcp_shuffle_mode_name[] = {
194     "SHUFFLE OFF",
195     "SHUFFLE ALL TRACKS",
196     "SHUFFLE GROUP"
197 };
198 
199 const char * avrcp_shuffle2str(uint8_t index){
200     if ((index >= 1) && (index <= 3)) return avrcp_shuffle_mode_name[index-1];
201     return "NONE";
202 }
203 
204 static const char * avrcp_repeat_mode_name[] = {
205     "REPEAT OFF",
206     "REPEAT SINGLE TRACK",
207     "REPEAT ALL TRACKS",
208     "REPEAT GROUP"
209 };
210 
211 const char * avrcp_repeat2str(uint8_t index){
212     if ((index >= 1) && (index <= 4)) return avrcp_repeat_mode_name[index-1];
213     return "NONE";
214 }
215 
216 static const char * notification_name[] = {
217     "INVALID_INDEX",
218     "PLAYBACK_STATUS_CHANGED",
219     "TRACK_CHANGED",
220     "TRACK_REACHED_END",
221     "TRACK_REACHED_START",
222     "PLAYBACK_POS_CHANGED",
223     "BATT_STATUS_CHANGED",
224     "SYSTEM_STATUS_CHANGED",
225     "PLAYER_APPLICATION_SETTING_CHANGED",
226     "NOW_PLAYING_CONTENT_CHANGED",
227     "AVAILABLE_PLAYERS_CHANGED",
228     "ADDRESSED_PLAYER_CHANGED",
229     "UIDS_CHANGED",
230     "VOLUME_CHANGED",
231     "MAX_VALUE"
232 };
233 
234 const char * avrcp_notification2str(avrcp_notification_event_id_t index){
235     if ((index >= AVRCP_NOTIFICATION_EVENT_FIRST_INDEX) && (index <= AVRCP_NOTIFICATION_EVENT_LAST_INDEX)){
236         return notification_name[index];
237     }
238     return notification_name[0];
239 }
240 
241 btstack_linked_list_t avrcp_get_connections(void){
242     return avrcp_connections;
243 }
244 
245 uint8_t avrcp_cmd_opcode(uint8_t *packet, uint16_t size){
246     uint8_t cmd_opcode_index = 5;
247     if (cmd_opcode_index > size) return AVRCP_CMD_OPCODE_UNDEFINED;
248     return packet[cmd_opcode_index];
249 }
250 
251 void avrcp_create_sdp_record(uint8_t controller, uint8_t * service, uint32_t service_record_handle, uint8_t browsing, uint16_t supported_features,
252     const char * service_name, const char * service_provider_name){
253     uint8_t* attribute;
254     de_create_sequence(service);
255 
256     // 0x0000 "Service Record Handle"
257     de_add_number(service, DE_UINT, DE_SIZE_16, BLUETOOTH_ATTRIBUTE_SERVICE_RECORD_HANDLE);
258     de_add_number(service, DE_UINT, DE_SIZE_32, service_record_handle);
259 
260     // 0x0001 "Service Class ID List"
261     de_add_number(service,  DE_UINT, DE_SIZE_16, BLUETOOTH_ATTRIBUTE_SERVICE_CLASS_ID_LIST);
262     attribute = de_push_sequence(service);
263     {
264         if (controller){
265             de_add_number(attribute, DE_UUID, DE_SIZE_16, BLUETOOTH_SERVICE_CLASS_AV_REMOTE_CONTROL);
266             de_add_number(attribute, DE_UUID, DE_SIZE_16, BLUETOOTH_SERVICE_CLASS_AV_REMOTE_CONTROL_CONTROLLER);
267         } else {
268             de_add_number(attribute, DE_UUID, DE_SIZE_16, BLUETOOTH_SERVICE_CLASS_AV_REMOTE_CONTROL_TARGET);
269         }
270     }
271     de_pop_sequence(service, attribute);
272 
273     // 0x0004 "Protocol Descriptor List"
274     de_add_number(service,  DE_UINT, DE_SIZE_16, BLUETOOTH_ATTRIBUTE_PROTOCOL_DESCRIPTOR_LIST);
275     attribute = de_push_sequence(service);
276     {
277         uint8_t* l2cpProtocol = de_push_sequence(attribute);
278         {
279             de_add_number(l2cpProtocol,  DE_UUID, DE_SIZE_16, BLUETOOTH_PROTOCOL_L2CAP);
280             de_add_number(l2cpProtocol,  DE_UINT, DE_SIZE_16, BLUETOOTH_PSM_AVCTP);
281         }
282         de_pop_sequence(attribute, l2cpProtocol);
283 
284         uint8_t* avctpProtocol = de_push_sequence(attribute);
285         {
286             de_add_number(avctpProtocol,  DE_UUID, DE_SIZE_16, BLUETOOTH_PROTOCOL_AVCTP);  // avctpProtocol_service
287             de_add_number(avctpProtocol,  DE_UINT, DE_SIZE_16,  0x0104);    // version
288         }
289         de_pop_sequence(attribute, avctpProtocol);
290     }
291     de_pop_sequence(service, attribute);
292 
293     // 0x0005 "Public Browse Group"
294     de_add_number(service,  DE_UINT, DE_SIZE_16, BLUETOOTH_ATTRIBUTE_BROWSE_GROUP_LIST); // public browse group
295     attribute = de_push_sequence(service);
296     {
297         de_add_number(attribute,  DE_UUID, DE_SIZE_16, BLUETOOTH_ATTRIBUTE_PUBLIC_BROWSE_ROOT);
298     }
299     de_pop_sequence(service, attribute);
300 
301     // 0x0009 "Bluetooth Profile Descriptor List"
302     de_add_number(service,  DE_UINT, DE_SIZE_16, BLUETOOTH_ATTRIBUTE_BLUETOOTH_PROFILE_DESCRIPTOR_LIST);
303     attribute = de_push_sequence(service);
304     {
305         uint8_t *avrcProfile = de_push_sequence(attribute);
306         {
307             de_add_number(avrcProfile,  DE_UUID, DE_SIZE_16, BLUETOOTH_SERVICE_CLASS_AV_REMOTE_CONTROL);
308             de_add_number(avrcProfile,  DE_UINT, DE_SIZE_16, 0x0106);
309         }
310         de_pop_sequence(attribute, avrcProfile);
311     }
312     de_pop_sequence(service, attribute);
313 
314     // 0x000d "Additional Bluetooth Profile Descriptor List"
315     if (browsing){
316         de_add_number(service,  DE_UINT, DE_SIZE_16, BLUETOOTH_ATTRIBUTE_ADDITIONAL_PROTOCOL_DESCRIPTOR_LISTS);
317         attribute = de_push_sequence(service);
318         {
319             uint8_t * des = de_push_sequence(attribute);
320             {
321                 uint8_t* browsing_l2cpProtocol = de_push_sequence(des);
322                 {
323                     de_add_number(browsing_l2cpProtocol,  DE_UUID, DE_SIZE_16, BLUETOOTH_PROTOCOL_L2CAP);
324                     de_add_number(browsing_l2cpProtocol,  DE_UINT, DE_SIZE_16, BLUETOOTH_PSM_AVCTP_BROWSING);
325                 }
326                 de_pop_sequence(des, browsing_l2cpProtocol);
327 
328                 uint8_t* browsing_avctpProtocol = de_push_sequence(des);
329                 {
330                     de_add_number(browsing_avctpProtocol,  DE_UUID, DE_SIZE_16, BLUETOOTH_PROTOCOL_AVCTP);  // browsing_avctpProtocol_service
331                     de_add_number(browsing_avctpProtocol,  DE_UINT, DE_SIZE_16, 0x0104);                   // version
332                 }
333                 de_pop_sequence(des, browsing_avctpProtocol);
334             }
335             de_pop_sequence(attribute, des);
336         }
337         de_pop_sequence(service, attribute);
338     }
339 
340 
341     // 0x0100 "Service Name"
342     de_add_number(service,  DE_UINT, DE_SIZE_16, 0x0100);
343     if (service_name){
344         de_add_data(service,  DE_STRING, (uint16_t) strlen(service_name), (uint8_t *) service_name);
345     } else {
346         if (controller){
347             de_add_data(service, DE_STRING, (uint16_t) strlen(avrcp_default_controller_service_name), (uint8_t *) avrcp_default_controller_service_name);
348         } else {
349             de_add_data(service, DE_STRING, (uint16_t) strlen(avrcp_defaul_target_service_name), (uint8_t *) avrcp_defaul_target_service_name);
350         }
351     }
352 
353     // 0x0100 "Provider Name"
354     de_add_number(service,  DE_UINT, DE_SIZE_16, 0x0102);
355     if (service_provider_name){
356         de_add_data(service,  DE_STRING, (uint16_t) strlen(service_provider_name), (uint8_t *) service_provider_name);
357     } else {
358         if (controller){
359             de_add_data(service, DE_STRING, (uint16_t) strlen(avrcp_default_controller_service_provider_name), (uint8_t *) avrcp_default_controller_service_provider_name);
360         } else {
361             de_add_data(service, DE_STRING, (uint16_t) strlen(avrcp_default_target_service_provider_name), (uint8_t *) avrcp_default_target_service_provider_name);
362         }
363     }
364 
365     // 0x0311 "Supported Features"
366     de_add_number(service, DE_UINT, DE_SIZE_16, 0x0311);
367     de_add_number(service, DE_UINT, DE_SIZE_16, supported_features);
368 }
369 
370 uint16_t avctp_get_num_bytes_for_header(avctp_packet_type_t avctp_packet_type) {
371     switch (avctp_packet_type){
372         case AVCTP_SINGLE_PACKET:
373             // AVCTP message: transport header (1), pid (2)
374             return 3;
375         case AVCTP_START_PACKET:
376             // AVCTP message: transport header (1), num_packets (1), pid (2)
377             return 4;
378         default:
379             // AVCTP message: transport header (1)
380             return 1;
381     }
382 }
383 
384 uint16_t avrcp_get_num_bytes_for_header(avrcp_command_opcode_t command_opcode, avctp_packet_type_t avctp_packet_type) {
385     switch (avctp_packet_type){
386         case AVCTP_SINGLE_PACKET:
387         case AVCTP_START_PACKET:
388             break;
389         default:
390             return 0;
391     }
392 
393     uint16_t offset = 3; // AVRCP message: cmd type (1), subunit (1), opcode (1)
394     switch (command_opcode){
395         case AVRCP_CMD_OPCODE_VENDOR_DEPENDENT:
396             offset += 7; // AVRCP message:  company (3), pdu id(1), AVRCP packet type (1), param_len (2)
397             break;
398         case AVRCP_CMD_OPCODE_PASS_THROUGH:
399             offset += 3;  // AVRCP message: operation id (1), param_len (2)
400             break;
401         default:
402             break;
403     }
404     return offset;
405 }
406 
407 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){
408     uint16_t max_frame_size = btstack_min(l2cap_mtu, AVRCP_MAX_AV_C_MESSAGE_FRAME_SIZE);
409     uint16_t payload_offset = avctp_get_num_bytes_for_header(avctp_packet_type) +
410                               avrcp_get_num_bytes_for_header(command_opcode, avctp_packet_type);
411 
412     btstack_assert(max_frame_size >= payload_offset);
413     return (max_frame_size - payload_offset);
414 }
415 
416 
417 avctp_packet_type_t avctp_get_packet_type(avrcp_connection_t * connection, uint16_t * max_payload_size){
418     if (connection->l2cap_mtu >= AVRCP_MAX_AV_C_MESSAGE_FRAME_SIZE){
419         return AVCTP_SINGLE_PACKET;
420     }
421 
422     if (connection->data_offset == 0){
423         uint16_t max_payload_size_for_single_packet = avrcp_get_num_free_bytes_for_payload(connection->l2cap_mtu,
424                                                                  connection->command_opcode,
425                                                                  AVCTP_SINGLE_PACKET);
426         if (max_payload_size_for_single_packet >= connection->data_len){
427             *max_payload_size = max_payload_size_for_single_packet;
428             return AVCTP_SINGLE_PACKET;
429         } else {
430             uint16_t max_payload_size_for_start_packet = max_payload_size_for_single_packet - 1;
431             *max_payload_size = max_payload_size_for_start_packet;
432             return AVCTP_START_PACKET;
433         }
434     } else {
435         // both packet types have the same single byte AVCTP header
436         *max_payload_size = avrcp_get_num_free_bytes_for_payload(connection->l2cap_mtu,
437                                                                  connection->command_opcode,
438                                                                  AVCTP_CONTINUE_PACKET);
439         if ((connection->data_len - connection->data_offset) > *max_payload_size){
440             return AVCTP_CONTINUE_PACKET;
441         } else {
442             return AVCTP_END_PACKET;
443         }
444     }
445 }
446 
447 avrcp_packet_type_t avrcp_get_packet_type(avrcp_connection_t * connection){
448     switch (connection->avctp_packet_type) {
449         case AVCTP_SINGLE_PACKET:
450         case AVCTP_START_PACKET:
451             break;
452         default:
453             return connection->avrcp_packet_type;
454     }
455 
456     uint16_t payload_offset = avctp_get_num_bytes_for_header(connection->avctp_packet_type) +
457                               avrcp_get_num_bytes_for_header(connection->command_opcode, connection->avctp_packet_type);
458     uint16_t bytes_to_send = (connection->data_len - connection->data_offset) + payload_offset;
459 
460     if (connection->data_offset == 0){
461         if (bytes_to_send <= AVRCP_MAX_AV_C_MESSAGE_FRAME_SIZE){
462             return AVRCP_SINGLE_PACKET;
463         } else {
464             return AVRCP_START_PACKET;
465         }
466     } else {
467         if (bytes_to_send > AVRCP_MAX_AV_C_MESSAGE_FRAME_SIZE){
468             return AVRCP_CONTINUE_PACKET;
469         } else {
470             return AVRCP_END_PACKET;
471         }
472     }
473 }
474 
475 avrcp_connection_t * avrcp_get_connection_for_bd_addr_for_role(avrcp_role_t role, bd_addr_t addr){
476     btstack_linked_list_iterator_t it;
477     btstack_linked_list_iterator_init(&it, (btstack_linked_list_t *) &avrcp_connections);
478     while (btstack_linked_list_iterator_has_next(&it)){
479         avrcp_connection_t * connection = (avrcp_connection_t *)btstack_linked_list_iterator_next(&it);
480         if (connection->role != role) continue;
481         if (memcmp(addr, connection->remote_addr, 6) != 0) continue;
482         return connection;
483     }
484     return NULL;
485 }
486 
487 avrcp_connection_t * avrcp_get_connection_for_l2cap_signaling_cid_for_role(avrcp_role_t role, uint16_t l2cap_cid){
488     btstack_linked_list_iterator_t it;
489     btstack_linked_list_iterator_init(&it, (btstack_linked_list_t *) &avrcp_connections);
490     while (btstack_linked_list_iterator_has_next(&it)){
491         avrcp_connection_t * connection = (avrcp_connection_t *)btstack_linked_list_iterator_next(&it);
492         if (connection->role != role) continue;
493         if (connection->l2cap_signaling_cid != l2cap_cid) continue;
494         return connection;
495     }
496     return NULL;
497 }
498 
499 avrcp_connection_t * avrcp_get_connection_for_avrcp_cid_for_role(avrcp_role_t role, uint16_t avrcp_cid){
500     btstack_linked_list_iterator_t it;
501     btstack_linked_list_iterator_init(&it, (btstack_linked_list_t *) &avrcp_connections);
502     while (btstack_linked_list_iterator_has_next(&it)){
503         avrcp_connection_t * connection = (avrcp_connection_t *)btstack_linked_list_iterator_next(&it);
504         if (connection->role != role) continue;
505         if (connection->avrcp_cid != avrcp_cid) continue;
506         return connection;
507     }
508     return NULL;
509 }
510 
511 avrcp_connection_t * avrcp_get_connection_for_browsing_cid_for_role(avrcp_role_t role, uint16_t browsing_cid){
512     btstack_linked_list_iterator_t it;
513     btstack_linked_list_iterator_init(&it, (btstack_linked_list_t *) &avrcp_connections);
514     while (btstack_linked_list_iterator_has_next(&it)){
515         avrcp_connection_t * connection = (avrcp_connection_t *)btstack_linked_list_iterator_next(&it);
516         if (connection->role != role) continue;
517         if (connection->avrcp_browsing_cid != browsing_cid) continue;
518         return connection;
519     }
520     return NULL;
521 }
522 
523 avrcp_connection_t * avrcp_get_connection_for_browsing_l2cap_cid_for_role(avrcp_role_t role, uint16_t browsing_l2cap_cid){
524     btstack_linked_list_iterator_t it;
525     btstack_linked_list_iterator_init(&it, (btstack_linked_list_t *) &avrcp_connections);
526     while (btstack_linked_list_iterator_has_next(&it)){
527         avrcp_connection_t * connection = (avrcp_connection_t *)btstack_linked_list_iterator_next(&it);
528         if (connection->role != role) continue;
529         if (connection->browsing_connection &&  (connection->browsing_connection->l2cap_browsing_cid != browsing_l2cap_cid)) continue;
530         return connection;
531     }
532     return NULL;
533 }
534 
535 avrcp_browsing_connection_t * avrcp_get_browsing_connection_for_l2cap_cid_for_role(avrcp_role_t role, uint16_t l2cap_cid){
536     btstack_linked_list_iterator_t it;
537     btstack_linked_list_iterator_init(&it, (btstack_linked_list_t *) &avrcp_connections);
538     while (btstack_linked_list_iterator_has_next(&it)){
539         avrcp_connection_t * connection = (avrcp_connection_t *)btstack_linked_list_iterator_next(&it);
540         if (connection->role != role) continue;
541         if (connection->browsing_connection && (connection->browsing_connection->l2cap_browsing_cid != l2cap_cid)) continue;
542         return connection->browsing_connection;
543     }
544     return NULL;
545 }
546 
547 void avrcp_request_can_send_now(avrcp_connection_t * connection, uint16_t l2cap_cid){
548     connection->wait_to_send = true;
549     l2cap_request_can_send_now_event(l2cap_cid);
550 }
551 
552 uint16_t avrcp_get_next_cid(avrcp_role_t role){
553     do {
554         if (avrcp_cid_counter == 0xffff) {
555             avrcp_cid_counter = 1;
556         } else {
557             avrcp_cid_counter++;
558         }
559     } while (avrcp_get_connection_for_avrcp_cid_for_role(role, avrcp_cid_counter) !=  NULL) ;
560     return avrcp_cid_counter;
561 }
562 
563 static avrcp_connection_t * avrcp_create_connection(avrcp_role_t role, bd_addr_t remote_addr){
564     avrcp_connection_t * connection = btstack_memory_avrcp_connection_get();
565     if (!connection){
566         log_error("Not enough memory to create connection for role %d", role);
567         return NULL;
568     }
569 
570     connection->state = AVCTP_CONNECTION_IDLE;
571     connection->role = role;
572 
573     connection->transaction_id = 0xFF;
574     connection->transaction_id_counter = 0;
575 
576     connection->controller_max_num_fragments = 0xFF;
577 
578     // setup default unit / subunit info
579     connection->company_id = 0xffffff;
580     connection->target_unit_type = AVRCP_SUBUNIT_TYPE_PANEL;
581     connection->target_subunit_info_data_size = sizeof(avrcp_default_subunit_info);
582     connection->target_subunit_info_data = avrcp_default_subunit_info;
583 
584     log_info("avrcp_create_connection, role %d", role);
585     (void)memcpy(connection->remote_addr, remote_addr, 6);
586     btstack_linked_list_add(&avrcp_connections, (btstack_linked_item_t *) connection);
587     return connection;
588 }
589 
590 static void avrcp_finalize_connection(avrcp_connection_t * connection){
591     btstack_run_loop_remove_timer(&connection->retry_timer);
592     btstack_run_loop_remove_timer(&connection->controller_press_and_hold_cmd_timer);
593     btstack_linked_list_remove(&avrcp_connections, (btstack_linked_item_t*) connection);
594     btstack_memory_avrcp_connection_free(connection);
595 }
596 
597 static void avrcp_emit_connection_established(uint16_t avrcp_cid, bd_addr_t addr, hci_con_handle_t con_handle, uint8_t status){
598     btstack_assert(avrcp_callback != NULL);
599 
600     uint8_t event[14];
601     int pos = 0;
602     event[pos++] = HCI_EVENT_AVRCP_META;
603     event[pos++] = sizeof(event) - 2;
604     event[pos++] = AVRCP_SUBEVENT_CONNECTION_ESTABLISHED;
605     event[pos++] = status;
606     little_endian_store_16(event, pos, avrcp_cid);
607     pos += 2;
608     reverse_bd_addr(addr,&event[pos]);
609     pos += 6;
610     little_endian_store_16(event, pos, con_handle);
611     pos += 2;
612     (*avrcp_callback)(HCI_EVENT_PACKET, 0, event, sizeof(event));
613 }
614 
615 static void avrcp_emit_connection_closed(uint16_t avrcp_cid){
616     btstack_assert(avrcp_callback != NULL);
617 
618     uint8_t event[5];
619     int pos = 0;
620     event[pos++] = HCI_EVENT_AVRCP_META;
621     event[pos++] = sizeof(event) - 2;
622     event[pos++] = AVRCP_SUBEVENT_CONNECTION_RELEASED;
623     little_endian_store_16(event, pos, avrcp_cid);
624     pos += 2;
625     (*avrcp_callback)(HCI_EVENT_PACKET, 0, event, sizeof(event));
626 }
627 
628 uint16_t avrcp_sdp_query_browsing_l2cap_psm(void){
629     return avrcp_sdp_query_context.browsing_l2cap_psm;
630 }
631 
632 void avrcp_handle_sdp_client_query_attribute_value(uint8_t *packet){
633     des_iterator_t des_list_it;
634 
635     des_iterator_t additional_protocol_descriptor_list_it;
636     des_iterator_t protocol_descriptor_list_it;
637     des_iterator_t protocol_it;
638     uint8_t protocol_descriptor_id;
639 
640     // Handle new SDP record
641     if (sdp_event_query_attribute_byte_get_record_id(packet) != avrcp_sdp_query_context.record_id) {
642         avrcp_sdp_query_context.record_id = sdp_event_query_attribute_byte_get_record_id(packet);
643         avrcp_sdp_query_context.parse_sdp_record = 0;
644         // log_info("SDP Record: Nr: %d", record_id);
645     }
646 
647     if (sdp_event_query_attribute_byte_get_attribute_length(packet) <= avrcp_sdp_query_attribute_value_buffer_size) {
648         avrcp_sdp_query_attribute_value[sdp_event_query_attribute_byte_get_data_offset(packet)] = sdp_event_query_attribute_byte_get_data(packet);
649 
650         if ((uint16_t)(sdp_event_query_attribute_byte_get_data_offset(packet)+1) == sdp_event_query_attribute_byte_get_attribute_length(packet)) {
651             switch(sdp_event_query_attribute_byte_get_attribute_id(packet)) {
652                 case BLUETOOTH_ATTRIBUTE_SERVICE_CLASS_ID_LIST:
653                     if (de_get_element_type(avrcp_sdp_query_attribute_value) != DE_DES) break;
654                     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)) {
655                         uint8_t * element = des_iterator_get_element(&des_list_it);
656                         if (de_get_element_type(element) != DE_UUID) continue;
657                         uint32_t uuid = de_get_uuid32(element);
658                         switch (uuid){
659                             case BLUETOOTH_SERVICE_CLASS_AV_REMOTE_CONTROL_TARGET:
660                             case BLUETOOTH_SERVICE_CLASS_AV_REMOTE_CONTROL:
661                             case BLUETOOTH_SERVICE_CLASS_AV_REMOTE_CONTROL_CONTROLLER:
662                                 avrcp_sdp_query_context.parse_sdp_record = 1;
663                                 break;
664                             default:
665                                 break;
666                         }
667                     }
668                     break;
669 
670                 case BLUETOOTH_ATTRIBUTE_PROTOCOL_DESCRIPTOR_LIST:
671                     if (!avrcp_sdp_query_context.parse_sdp_record) break;
672 
673                     for (des_iterator_init(&protocol_descriptor_list_it, avrcp_sdp_query_attribute_value); des_iterator_has_more(&protocol_descriptor_list_it); des_iterator_next(&protocol_descriptor_list_it)) {
674 
675                         if (des_iterator_get_type(&protocol_descriptor_list_it) != DE_DES) continue;
676                         uint8_t * protocol_descriptor_list_element = des_iterator_get_element(&protocol_descriptor_list_it);
677 
678                         des_iterator_init(&protocol_it, protocol_descriptor_list_element);
679                         uint8_t * protocol_element = des_iterator_get_element(&protocol_it);
680 
681                         if (de_get_element_type(protocol_element) != DE_UUID) continue;
682 
683                         uint32_t uuid = de_get_uuid32(protocol_element);
684                         des_iterator_next(&protocol_it);
685                         switch (uuid){
686                             case BLUETOOTH_PROTOCOL_L2CAP:
687                                 if (!des_iterator_has_more(&protocol_it)) continue;
688                                 de_element_get_uint16(des_iterator_get_element(&protocol_it), &avrcp_sdp_query_context.avrcp_l2cap_psm);
689                                 break;
690                             case BLUETOOTH_PROTOCOL_AVCTP:
691                                 if (!des_iterator_has_more(&protocol_it)) continue;
692                                 de_element_get_uint16(des_iterator_get_element(&protocol_it), &avrcp_sdp_query_context.avrcp_version);
693                                 break;
694                             default:
695                                 break;
696                         }
697                     }
698                     break;
699 
700                 case BLUETOOTH_ATTRIBUTE_ADDITIONAL_PROTOCOL_DESCRIPTOR_LISTS:
701                     if (!avrcp_sdp_query_context.parse_sdp_record) break;
702 
703                     protocol_descriptor_id = 0;
704 
705                     for ( des_iterator_init(&additional_protocol_descriptor_list_it, avrcp_sdp_query_attribute_value);
706                           des_iterator_has_more(&additional_protocol_descriptor_list_it);
707                           des_iterator_next(&additional_protocol_descriptor_list_it)) {
708 
709                         if (des_iterator_get_type(&additional_protocol_descriptor_list_it) != DE_DES) continue;
710                         uint8_t *additional_protocol_descriptor_element = des_iterator_get_element(&additional_protocol_descriptor_list_it);
711 
712                         for ( des_iterator_init(&protocol_descriptor_list_it,additional_protocol_descriptor_element);
713                               des_iterator_has_more(&protocol_descriptor_list_it);
714                               des_iterator_next(&protocol_descriptor_list_it)) {
715 
716                             if (des_iterator_get_type(&protocol_descriptor_list_it) != DE_DES) continue;
717 
718                             uint8_t * protocol_descriptor_list_element = des_iterator_get_element(&protocol_descriptor_list_it);
719 
720                             des_iterator_init(&protocol_it, protocol_descriptor_list_element);
721                             uint8_t * protocol_element = des_iterator_get_element(&protocol_it);
722 
723                             if (de_get_element_type(protocol_element) != DE_UUID) continue;
724 
725                             uint32_t uuid = de_get_uuid32(protocol_element);
726                             des_iterator_next(&protocol_it);
727                             switch (uuid) {
728                                 case BLUETOOTH_PROTOCOL_L2CAP:
729                                     if (!des_iterator_has_more(&protocol_it)) continue;
730                                     switch (protocol_descriptor_id) {
731                                         case 0:
732                                             de_element_get_uint16(des_iterator_get_element(&protocol_it),
733                                                                   &avrcp_sdp_query_context.browsing_l2cap_psm);
734                                             break;
735                                         case 1:
736                                             de_element_get_uint16(des_iterator_get_element(&protocol_it),
737                                                                   &avrcp_sdp_query_context.cover_art_l2cap_psm);
738                                             break;
739                                         default:
740                                             break;
741                                     }
742                                     break;
743                                 case BLUETOOTH_PROTOCOL_AVCTP:
744                                     if (!des_iterator_has_more(&protocol_it)) continue;
745                                     de_element_get_uint16(des_iterator_get_element(&protocol_it),
746                                                           &avrcp_sdp_query_context.browsing_version);
747                                     break;
748                                 default:
749                                     break;
750                             }
751                         }
752                         protocol_descriptor_id++;
753                     }
754                     break;
755 
756                 default:
757                     break;
758             }
759         }
760     } else {
761         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));
762     }
763 }
764 
765 static void avrcp_signaling_handle_sdp_query_complete(avrcp_connection_t * connection, uint8_t status){
766 
767     // l2cap available?
768     if (status == ERROR_CODE_SUCCESS){
769         if (avrcp_sdp_query_context.avrcp_l2cap_psm == 0){
770             status = SDP_SERVICE_NOT_FOUND;
771         }
772     }
773 
774     if (status == ERROR_CODE_SUCCESS){
775         // ready to connect
776         connection->state = AVCTP_CONNECTION_W2_L2CAP_CONNECT;
777 
778         // check if both events have been handled
779         avrcp_connection_t * connection_with_opposite_role;
780         switch (connection->role){
781             case AVRCP_CONTROLLER:
782                 connection_with_opposite_role = avrcp_get_connection_for_avrcp_cid_for_role(AVRCP_TARGET, connection->avrcp_cid);
783                 break;
784             case AVRCP_TARGET:
785                 connection_with_opposite_role = avrcp_get_connection_for_avrcp_cid_for_role(AVRCP_CONTROLLER, connection->avrcp_cid);
786                 break;
787             default:
788                 btstack_assert(false);
789                 return;
790         }
791         if (connection_with_opposite_role->state == AVCTP_CONNECTION_W4_L2CAP_CONNECTED){
792             connection->state                    = AVCTP_CONNECTION_W4_L2CAP_CONNECTED;
793             connection_with_opposite_role->state = AVCTP_CONNECTION_W4_L2CAP_CONNECTED;
794             l2cap_create_channel(&avrcp_packet_handler, connection->remote_addr, connection->avrcp_l2cap_psm, l2cap_max_mtu(), NULL);
795         }
796     } else {
797         log_info("AVRCP: SDP query failed with status 0x%02x.", status);
798         avrcp_emit_connection_established(connection->avrcp_cid, connection->remote_addr, connection->con_handle, status);
799         avrcp_finalize_connection(connection);
800     }
801 }
802 
803 static void avrcp_handle_sdp_query_completed(avrcp_connection_t * connection, uint8_t status){
804     btstack_assert(connection != NULL);
805 
806     // cache SDP result on success
807     if (status == ERROR_CODE_SUCCESS){
808         connection->avrcp_l2cap_psm = avrcp_sdp_query_context.avrcp_l2cap_psm;
809         connection->browsing_version = avrcp_sdp_query_context.browsing_version;
810         connection->browsing_l2cap_psm = avrcp_sdp_query_context.browsing_l2cap_psm;
811     }
812 
813     // SDP Signaling Query?
814     if (connection->state == AVCTP_CONNECTION_W4_SDP_QUERY_COMPLETE){
815         avrcp_signaling_handle_sdp_query_complete(connection, status);
816         return;
817     }
818     // Browsing SDP <- Browsing Connection <- Existing SDP Connection => it wasn't an SDP query for signaling
819     if (avrcp_browsing_sdp_query_complete_handler != NULL){
820         (*avrcp_browsing_sdp_query_complete_handler)(connection, status);
821     }
822 }
823 
824 static void avrcp_handle_sdp_client_query_result(uint8_t packet_type, uint16_t channel, uint8_t *packet, uint16_t size){
825     UNUSED(packet_type);
826     UNUSED(channel);
827     UNUSED(size);
828 
829     avrcp_connection_t * avrcp_target_connection     = avrcp_get_connection_for_avrcp_cid_for_role(AVRCP_TARGET,     avrcp_sdp_query_context.avrcp_cid);
830     avrcp_connection_t * avrcp_controller_connection = avrcp_get_connection_for_avrcp_cid_for_role(AVRCP_CONTROLLER, avrcp_sdp_query_context.avrcp_cid);
831     bool state_ok = (avrcp_target_connection != NULL) && (avrcp_controller_connection != NULL);
832 
833     if (!state_ok){
834         // something wrong, nevertheless, start next sdp query if this one is complete
835         if (hci_event_packet_get_type(packet) == SDP_EVENT_QUERY_COMPLETE){
836             avrcp_sdp_query_context.avrcp_cid = 0;
837             avrcp_start_next_sdp_query();
838         }
839         return;
840     }
841 
842     uint8_t status;
843 
844     switch (hci_event_packet_get_type(packet)){
845         case SDP_EVENT_QUERY_ATTRIBUTE_VALUE:
846             avrcp_handle_sdp_client_query_attribute_value(packet);
847             return;
848 
849         case SDP_EVENT_QUERY_COMPLETE:
850             // handle result
851             status = sdp_event_query_complete_get_status(packet);
852             avrcp_handle_sdp_query_completed(avrcp_controller_connection, status);
853             avrcp_handle_sdp_query_completed(avrcp_target_connection, status);
854 
855             // query done, start next one
856             avrcp_sdp_query_context.avrcp_cid = 0;
857             avrcp_start_next_sdp_query();
858             break;
859 
860         default:
861             return;
862     }
863 
864 }
865 
866 static void avrcp_handle_start_sdp_client_query(void * context){
867     UNUSED(context);
868 
869     avrcp_connection_t * avrcp_target_connection     = avrcp_get_connection_for_avrcp_cid_for_role(AVRCP_TARGET,     avrcp_sdp_query_context.avrcp_cid);
870     avrcp_connection_t * avrcp_controller_connection = avrcp_get_connection_for_avrcp_cid_for_role(AVRCP_CONTROLLER, avrcp_sdp_query_context.avrcp_cid);
871     bool state_ok = (avrcp_target_connection != NULL) && (avrcp_controller_connection != NULL);
872     if (state_ok == false){
873         // connection seems to got finalized in the meantime, just trigger next query
874         avrcp_start_next_sdp_query();
875         return;
876     }
877 
878     // prevent triggering SDP query twice (for each role once)
879     avrcp_target_connection->trigger_sdp_query = false;
880     avrcp_controller_connection->trigger_sdp_query = false;
881 
882     sdp_client_query_uuid16(&avrcp_handle_sdp_client_query_result, avrcp_target_connection->remote_addr, BLUETOOTH_PROTOCOL_AVCTP);
883 }
884 
885 static void avrcp_start_next_sdp_query(void) {
886     if (avrcp_sdp_query_context.avrcp_cid != 0) {
887         return;
888     }
889     btstack_linked_list_iterator_t it;
890     btstack_linked_list_iterator_init(&it, &avrcp_connections);
891     while (btstack_linked_list_iterator_has_next(&it)){
892         avrcp_connection_t * connection = (avrcp_connection_t *)btstack_linked_list_iterator_next(&it);
893         if (connection->trigger_sdp_query == false) continue;
894 
895         // we're ready => setup avrcp_sdp_query_context and request sdp query
896         avrcp_sdp_query_context.avrcp_cid = connection->avrcp_cid;
897         avrcp_sdp_query_context.avrcp_l2cap_psm = 0;
898         avrcp_sdp_query_context.avrcp_version  = 0;
899         avrcp_sdp_query_registration.callback = &avrcp_handle_start_sdp_client_query;
900         uint8_t status = sdp_client_register_query_callback(&avrcp_sdp_query_registration);
901         btstack_assert(status == ERROR_CODE_SUCCESS);
902         break;
903     }
904 }
905 
906 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){
907     if (connection == NULL){
908         connection = avrcp_create_connection(role, event_addr);
909     }
910     if (connection) {
911         connection->state = AVCTP_CONNECTION_W4_L2CAP_CONNECTED;
912         connection->l2cap_signaling_cid = local_cid;
913         connection->avrcp_cid = avrcp_cid;
914         connection->con_handle = con_handle;
915         btstack_run_loop_remove_timer(&connection->retry_timer);
916     }
917     return connection;
918 }
919 
920 static void avrcp_handle_open_connection(avrcp_connection_t * connection, hci_con_handle_t con_handle, uint16_t local_cid, uint16_t l2cap_mtu){
921     connection->l2cap_signaling_cid = local_cid;
922     connection->l2cap_mtu = l2cap_mtu;
923     connection->con_handle = con_handle;
924     connection->incoming_declined = false;
925     connection->target_song_length_ms = 0xFFFFFFFF;
926     connection->target_song_position_ms = 0xFFFFFFFF;
927     memset(connection->target_track_id, 0xFF, 8);
928     connection->target_track_selected = false;
929     connection->target_track_changed = false;
930     connection->target_playback_status = AVRCP_PLAYBACK_STATUS_STOPPED;
931     connection->state = AVCTP_CONNECTION_OPENED;
932 
933     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);
934 }
935 
936 static void avrcp_retry_timer_timeout_handler(btstack_timer_source_t * timer){
937     uint16_t avrcp_cid = (uint16_t)(uintptr_t) btstack_run_loop_get_timer_context(timer);
938     avrcp_connection_t * connection_controller = avrcp_get_connection_for_avrcp_cid_for_role(AVRCP_CONTROLLER, avrcp_cid);
939     if (connection_controller == NULL) return;
940     avrcp_connection_t * connection_target = avrcp_get_connection_for_avrcp_cid_for_role(AVRCP_TARGET, avrcp_cid);
941     if (connection_target == NULL) return;
942 
943     if (connection_controller->state == AVCTP_CONNECTION_W2_L2CAP_RETRY){
944         connection_controller->state = AVCTP_CONNECTION_W4_L2CAP_CONNECTED;
945         connection_target->state = AVCTP_CONNECTION_W4_L2CAP_CONNECTED;
946         l2cap_create_channel(&avrcp_packet_handler, connection_controller->remote_addr, connection_controller->avrcp_l2cap_psm, l2cap_max_mtu(), NULL);
947     }
948 }
949 
950 static void avrcp_retry_timer_start(avrcp_connection_t * connection){
951     btstack_run_loop_set_timer_handler(&connection->retry_timer, avrcp_retry_timer_timeout_handler);
952     btstack_run_loop_set_timer_context(&connection->retry_timer, (void *)(uintptr_t)connection->avrcp_cid);
953 
954     // add some jitter/randomness to reconnect delay
955     uint32_t timeout = 100 + (btstack_run_loop_get_time_ms() & 0x7F);
956     btstack_run_loop_set_timer(&connection->retry_timer, timeout);
957 
958     btstack_run_loop_add_timer(&connection->retry_timer);
959 }
960 
961 static avrcp_frame_type_t avrcp_get_frame_type(uint8_t header){
962     return (avrcp_frame_type_t)((header & 0x02) >> 1);
963 }
964 
965 static void avrcp_packet_handler(uint8_t packet_type, uint16_t channel, uint8_t *packet, uint16_t size){
966     UNUSED(channel);
967     UNUSED(size);
968     bd_addr_t event_addr;
969     uint16_t local_cid;
970     uint16_t l2cap_mtu;
971     uint8_t  status;
972     bool decline_connection;
973     bool outoing_active;
974     hci_con_handle_t con_handle;
975 
976     avrcp_connection_t * connection_controller;
977     avrcp_connection_t * connection_target;
978     bool can_send;
979 
980     switch (packet_type) {
981         case HCI_EVENT_PACKET:
982             switch (hci_event_packet_get_type(packet)) {
983 
984                 case L2CAP_EVENT_INCOMING_CONNECTION:
985                     btstack_assert(avrcp_controller_packet_handler != NULL);
986                     btstack_assert(avrcp_target_packet_handler != NULL);
987 
988                     l2cap_event_incoming_connection_get_address(packet, event_addr);
989                     local_cid = l2cap_event_incoming_connection_get_local_cid(packet);
990                     con_handle = l2cap_event_incoming_connection_get_handle(packet);
991 
992                     outoing_active = false;
993                     connection_target = avrcp_get_connection_for_bd_addr_for_role(AVRCP_TARGET, event_addr);
994                     if (connection_target != NULL){
995                         if (connection_target->state == AVCTP_CONNECTION_W4_L2CAP_CONNECTED){
996                             outoing_active = true;
997                             connection_target->incoming_declined = true;
998                         }
999                     }
1000 
1001                     connection_controller = avrcp_get_connection_for_bd_addr_for_role(AVRCP_CONTROLLER, event_addr);
1002                     if (connection_controller != NULL){
1003                         if (connection_controller->state == AVCTP_CONNECTION_W4_L2CAP_CONNECTED) {
1004                             outoing_active = true;
1005                             connection_controller->incoming_declined = true;
1006                         }
1007                     }
1008 
1009                     decline_connection = outoing_active;
1010                     if (decline_connection == false){
1011                         uint16_t avrcp_cid;
1012                         if ((connection_controller == NULL) || (connection_target == NULL)){
1013                             avrcp_cid = avrcp_get_next_cid(AVRCP_CONTROLLER);
1014                         } else {
1015                             avrcp_cid = connection_controller->avrcp_cid;
1016                         }
1017                         // create two connection objects (both)
1018                         connection_target     = avrcp_handle_incoming_connection_for_role(AVRCP_TARGET, connection_target, event_addr, con_handle, local_cid, avrcp_cid);
1019                         connection_controller = avrcp_handle_incoming_connection_for_role(AVRCP_CONTROLLER, connection_controller, event_addr, con_handle, local_cid, avrcp_cid);
1020                         if ((connection_target == NULL) || (connection_controller == NULL)){
1021                             decline_connection = true;
1022                             if (connection_target) {
1023                                 avrcp_finalize_connection(connection_target);
1024                             }
1025                             if (connection_controller) {
1026                                 avrcp_finalize_connection(connection_controller);
1027                             }
1028                         }
1029                     }
1030                     if (decline_connection){
1031                         l2cap_decline_connection(local_cid);
1032                     } else {
1033                         log_info("AVRCP: L2CAP_EVENT_INCOMING_CONNECTION local cid 0x%02x, state %d", local_cid, connection_controller->state);
1034                         l2cap_accept_connection(local_cid);
1035                     }
1036                     break;
1037 
1038                 case L2CAP_EVENT_CHANNEL_OPENED:
1039                     l2cap_event_channel_opened_get_address(packet, event_addr);
1040                     status = l2cap_event_channel_opened_get_status(packet);
1041                     local_cid = l2cap_event_channel_opened_get_local_cid(packet);
1042                     l2cap_mtu = l2cap_event_channel_opened_get_remote_mtu(packet);
1043                     con_handle = l2cap_event_channel_opened_get_handle(packet);
1044 
1045                     connection_controller = avrcp_get_connection_for_bd_addr_for_role(AVRCP_CONTROLLER, event_addr);
1046                     connection_target = avrcp_get_connection_for_bd_addr_for_role(AVRCP_TARGET, event_addr);
1047 
1048                     // incoming: structs are already created in L2CAP_EVENT_INCOMING_CONNECTION
1049                     // outgoing: structs are cteated in avrcp_connect()
1050                     if ((connection_controller == NULL) || (connection_target == NULL)) {
1051                         break;
1052                     }
1053 
1054                     switch (status){
1055                         case ERROR_CODE_SUCCESS:
1056                             avrcp_handle_open_connection(connection_target, con_handle, local_cid, l2cap_mtu);
1057                             avrcp_handle_open_connection(connection_controller, con_handle, local_cid, l2cap_mtu);
1058                             avrcp_emit_connection_established(connection_controller->avrcp_cid, event_addr, con_handle, status);
1059                             return;
1060                         case L2CAP_CONNECTION_RESPONSE_RESULT_REFUSED_RESOURCES:
1061                             if (connection_controller->incoming_declined == true){
1062                                 log_info("Incoming connection was declined, and the outgoing failed");
1063                                 connection_controller->state = AVCTP_CONNECTION_W2_L2CAP_RETRY;
1064                                 connection_controller->incoming_declined = false;
1065                                 connection_target->state = AVCTP_CONNECTION_W2_L2CAP_RETRY;
1066                                 connection_target->incoming_declined = false;
1067                                 avrcp_retry_timer_start(connection_controller);
1068                                 return;
1069                             }
1070                             break;
1071                         default:
1072                             break;
1073                     }
1074                     log_info("L2CAP connection to connection %s failed. status code 0x%02x", bd_addr_to_str(event_addr), status);
1075                     avrcp_emit_connection_established(connection_controller->avrcp_cid, event_addr, con_handle, status);
1076                     avrcp_finalize_connection(connection_controller);
1077                     avrcp_finalize_connection(connection_target);
1078 
1079                     break;
1080 
1081                 case L2CAP_EVENT_CHANNEL_CLOSED:
1082                     local_cid = l2cap_event_channel_closed_get_local_cid(packet);
1083 
1084                     connection_controller = avrcp_get_connection_for_l2cap_signaling_cid_for_role(AVRCP_CONTROLLER, local_cid);
1085                     connection_target = avrcp_get_connection_for_l2cap_signaling_cid_for_role(AVRCP_TARGET, local_cid);
1086                     if ((connection_controller == NULL) || (connection_target == NULL)) {
1087                         break;
1088                     }
1089                     avrcp_emit_connection_closed(connection_controller->avrcp_cid);
1090                     avrcp_finalize_connection(connection_controller);
1091                     avrcp_finalize_connection(connection_target);
1092                     break;
1093 
1094                 case L2CAP_EVENT_CAN_SEND_NOW:
1095                     local_cid = l2cap_event_can_send_now_get_local_cid(packet);
1096                     can_send = true;
1097 
1098                     connection_target = avrcp_get_connection_for_l2cap_signaling_cid_for_role(AVRCP_TARGET, local_cid);
1099                     if ((connection_target != NULL) && connection_target->wait_to_send){
1100                         connection_target->wait_to_send = false;
1101                         (*avrcp_target_packet_handler)(HCI_EVENT_PACKET, channel, packet, size);
1102                         can_send = false;
1103                     }
1104 
1105                     connection_controller = avrcp_get_connection_for_l2cap_signaling_cid_for_role(AVRCP_CONTROLLER, local_cid);
1106                     if ((connection_controller != NULL) && connection_controller->wait_to_send){
1107                         if (can_send){
1108                             connection_controller->wait_to_send = false;
1109                             (*avrcp_controller_packet_handler)(HCI_EVENT_PACKET, channel, packet, size);
1110                         } else {
1111                             l2cap_request_can_send_now_event(local_cid);
1112                         }
1113                     }
1114                     break;
1115 
1116                 default:
1117                     break;
1118             }
1119             break;
1120 
1121         case L2CAP_DATA_PACKET:
1122             switch (avrcp_get_frame_type(packet[0])){
1123                 case AVRCP_RESPONSE_FRAME:
1124                     (*avrcp_controller_packet_handler)(packet_type, channel, packet, size);
1125                     break;
1126                 case AVRCP_COMMAND_FRAME:
1127                 default:    // make compiler happy
1128                     (*avrcp_target_packet_handler)(packet_type, channel, packet, size);
1129                     break;
1130             }
1131             break;
1132 
1133         default:
1134             break;
1135     }
1136 }
1137 
1138 void avrcp_init(void){
1139     avrcp_connections = NULL;
1140     if (avrcp_l2cap_service_registered) return;
1141 
1142     int status = l2cap_register_service(&avrcp_packet_handler, BLUETOOTH_PSM_AVCTP, 0xffff, gap_get_security_level());
1143     if (status != ERROR_CODE_SUCCESS) return;
1144     avrcp_l2cap_service_registered = true;
1145 }
1146 
1147 void avrcp_register_controller_packet_handler(btstack_packet_handler_t callback){
1148     // note: called by avrcp_controller_init
1149     avrcp_controller_packet_handler = callback;
1150 }
1151 
1152 void avrcp_register_target_packet_handler(btstack_packet_handler_t callback){
1153     // note: called by avrcp_target_init
1154     avrcp_target_packet_handler = callback;
1155 }
1156 
1157 void avrcp_register_packet_handler(btstack_packet_handler_t callback){
1158     btstack_assert(callback != NULL);
1159     avrcp_callback = callback;
1160 }
1161 
1162 void avrcp_register_browsing_sdp_query_complete_handler(void (*callback)(avrcp_connection_t * connection, uint8_t status)){
1163     btstack_assert(callback != NULL);
1164     avrcp_browsing_sdp_query_complete_handler = callback;
1165 }
1166 
1167 
1168 void avrcp_trigger_sdp_query(avrcp_connection_t *connection_controller, avrcp_connection_t *connection_target) {
1169     connection_controller->trigger_sdp_query = true;
1170     connection_target->trigger_sdp_query     = true;
1171 
1172     avrcp_start_next_sdp_query();
1173 }
1174 
1175 uint8_t avrcp_connect(bd_addr_t remote_addr, uint16_t * avrcp_cid){
1176     btstack_assert(avrcp_controller_packet_handler != NULL);
1177     btstack_assert(avrcp_target_packet_handler != NULL);
1178 
1179     avrcp_connection_t * connection_controller = avrcp_get_connection_for_bd_addr_for_role(AVRCP_CONTROLLER, remote_addr);
1180     if (connection_controller){
1181         return ERROR_CODE_COMMAND_DISALLOWED;
1182     }
1183     avrcp_connection_t * connection_target = avrcp_get_connection_for_bd_addr_for_role(AVRCP_TARGET, remote_addr);
1184     if (connection_target){
1185         return ERROR_CODE_COMMAND_DISALLOWED;
1186     }
1187 
1188     uint16_t cid = avrcp_get_next_cid(AVRCP_CONTROLLER);
1189 
1190     connection_controller = avrcp_create_connection(AVRCP_CONTROLLER, remote_addr);
1191     if (!connection_controller) return BTSTACK_MEMORY_ALLOC_FAILED;
1192 
1193     connection_target = avrcp_create_connection(AVRCP_TARGET, remote_addr);
1194     if (!connection_target){
1195         avrcp_finalize_connection(connection_controller);
1196         return BTSTACK_MEMORY_ALLOC_FAILED;
1197     }
1198 
1199     if (avrcp_cid != NULL){
1200         *avrcp_cid = cid;
1201     }
1202 
1203     connection_controller->avrcp_cid = cid;
1204     connection_target->avrcp_cid     = cid;
1205 
1206     connection_controller->state = AVCTP_CONNECTION_W4_SDP_QUERY_COMPLETE;
1207     connection_target->state     = AVCTP_CONNECTION_W4_SDP_QUERY_COMPLETE;
1208 
1209     avrcp_trigger_sdp_query(connection_controller, connection_target);
1210 
1211     return ERROR_CODE_SUCCESS;
1212 }
1213 
1214 uint8_t avrcp_disconnect(uint16_t avrcp_cid){
1215     avrcp_connection_t * connection_controller = avrcp_get_connection_for_avrcp_cid_for_role(AVRCP_CONTROLLER, avrcp_cid);
1216     if (!connection_controller){
1217         return ERROR_CODE_UNKNOWN_CONNECTION_IDENTIFIER;
1218     }
1219     avrcp_connection_t * connection_target = avrcp_get_connection_for_avrcp_cid_for_role(AVRCP_TARGET, avrcp_cid);
1220     if (!connection_target){
1221         return ERROR_CODE_UNKNOWN_CONNECTION_IDENTIFIER;
1222     }
1223     if (connection_controller->browsing_connection){
1224         l2cap_disconnect(connection_controller->browsing_connection->l2cap_browsing_cid);
1225     }
1226     l2cap_disconnect(connection_controller->l2cap_signaling_cid);
1227     return ERROR_CODE_SUCCESS;
1228 }
1229 
1230 void avrcp_deinit(void){
1231     avrcp_l2cap_service_registered = false;
1232 
1233     avrcp_cid_counter = 0;
1234     avrcp_connections = NULL;
1235 
1236     avrcp_callback = NULL;
1237     avrcp_controller_packet_handler = NULL;
1238     avrcp_target_packet_handler = NULL;
1239 
1240     (void) memset(&avrcp_sdp_query_registration, 0, sizeof(avrcp_sdp_query_registration));
1241     (void) memset(&avrcp_sdp_query_context, 0, sizeof(avrcp_sdp_query_context_t));
1242     (void) memset(avrcp_sdp_query_attribute_value, 0, sizeof(avrcp_sdp_query_attribute_value));
1243 }
1244 #ifdef FUZZING_BUILD_MODE_UNSAFE_FOR_PRODUCTION
1245 #define FUZZ_CID 0x44
1246 #define FUZZ_CON_HANDLE 0x0001
1247 static bd_addr_t remote_addr = { 0x33, 0x33, 0x33, 0x33, 0x33, 0x33 };
1248 void avrcp_init_fuzz(void){
1249     // setup avrcp connections for cid
1250     avrcp_connection_t * connection_controller = avrcp_create_connection(AVRCP_CONTROLLER, remote_addr);
1251     avrcp_connection_t * connection_target     = avrcp_create_connection(AVRCP_TARGET, remote_addr);
1252     avrcp_handle_open_connection(connection_controller, FUZZ_CON_HANDLE, FUZZ_CID, 999);
1253     avrcp_handle_open_connection(connection_target, FUZZ_CON_HANDLE, FUZZ_CID, 999);
1254 }
1255 void avrcp_packet_handler_fuzz(uint8_t *packet, uint16_t size){
1256     avrcp_packet_handler(L2CAP_DATA_PACKET, FUZZ_CID, packet, size);
1257 }
1258 #endif
1259