xref: /btstack/src/classic/avdtp.c (revision cc92f22bee26a7cb6d2d16e105e8269f520f9968)
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 MATTHIAS
24  * RINGWALD OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
25  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
26  * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
27  * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
28  * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
29  * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF
30  * THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
31  * SUCH DAMAGE.
32  *
33  * Please inquire about commercial licensing options at
34  * [email protected]
35  *
36  */
37 
38 #define BTSTACK_FILE__ "avdtp.c"
39 
40 
41 #include <stdint.h>
42 #include <string.h>
43 
44 #include "bluetooth_psm.h"
45 #include "bluetooth_sdp.h"
46 #include "btstack_debug.h"
47 #include "btstack_event.h"
48 #include "btstack_memory.h"
49 #include "classic/avdtp.h"
50 #include "classic/avdtp_acceptor.h"
51 #include "classic/avdtp_initiator.h"
52 #include "classic/avdtp_util.h"
53 #include "classic/sdp_client.h"
54 #include "classic/sdp_util.h"
55 
56 btstack_linked_list_t stream_endpoints;
57 
58 static btstack_packet_handler_t avdtp_source_callback;
59 static btstack_packet_handler_t avdtp_sink_callback;
60 static btstack_context_callback_registration_t avdtp_handle_sdp_client_query_request;
61 
62 static uint16_t sdp_query_context_avdtp_cid = 0;
63 
64 static uint16_t stream_endpoints_id_counter = 0;
65 
66 static btstack_linked_list_t connections;
67 static uint16_t transaction_id_counter = 0;
68 
69 static int record_id = -1;
70 static uint8_t   attribute_value[45];
71 static const unsigned int attribute_value_buffer_size = sizeof(attribute_value);
72 
73 static void (*avdtp_sink_handle_media_data)(uint8_t local_seid, uint8_t *packet, uint16_t size);
74 
75 static uint16_t avdtp_cid_counter = 0;
76 
77 static void avdtp_handle_sdp_client_query_result(uint8_t packet_type, uint16_t channel, uint8_t *packet, uint16_t size);
78 
79 btstack_packet_handler_t
80 avdtp_packet_handler_for_stream_endpoint(const avdtp_stream_endpoint_t *stream_endpoint) {
81     return (stream_endpoint->sep.type == AVDTP_SOURCE) ? avdtp_source_callback : avdtp_sink_callback;
82 }
83 
84 void avdtp_emit_sink_and_source(uint8_t * packet, uint16_t size){
85     if (avdtp_source_callback != NULL){
86         (*avdtp_source_callback)(HCI_EVENT_PACKET, 0, packet, size);
87     }
88     if (avdtp_sink_callback != NULL){
89         (*avdtp_sink_callback)(HCI_EVENT_PACKET, 0, packet, size);
90     }
91 }
92 
93 void avdtp_emit_source(uint8_t * packet, uint16_t size){
94     if (avdtp_source_callback != NULL){
95         (*avdtp_source_callback)(HCI_EVENT_PACKET, 0, packet, size);
96     }
97 }
98 
99 btstack_linked_list_t * avdtp_get_stream_endpoints(void){
100     return &stream_endpoints;
101 }
102 
103 btstack_linked_list_t * avdtp_get_connections(void){
104     return &connections;
105 }
106 
107 static avdtp_connection_t * avdtp_get_connection_for_bd_addr(bd_addr_t addr){
108     btstack_linked_list_iterator_t it;
109     btstack_linked_list_iterator_init(&it, &connections);
110     while (btstack_linked_list_iterator_has_next(&it)){
111         avdtp_connection_t * connection = (avdtp_connection_t *)btstack_linked_list_iterator_next(&it);
112         if (memcmp(addr, connection->remote_addr, 6) != 0) continue;
113         return connection;
114     }
115     return NULL;
116 }
117 
118  avdtp_connection_t * avdtp_get_connection_for_avdtp_cid(uint16_t avdtp_cid){
119     btstack_linked_list_iterator_t it;
120     btstack_linked_list_iterator_init(&it, &connections);
121     while (btstack_linked_list_iterator_has_next(&it)){
122         avdtp_connection_t * connection = (avdtp_connection_t *)btstack_linked_list_iterator_next(&it);
123         if (connection->avdtp_cid != avdtp_cid) continue;
124         return connection;
125     }
126     return NULL;
127 }
128 
129 
130 avdtp_stream_endpoint_t * avdtp_get_stream_endpoint_for_seid(uint16_t seid){
131     btstack_linked_list_iterator_t it;
132     btstack_linked_list_iterator_init(&it, avdtp_get_stream_endpoints());
133     while (btstack_linked_list_iterator_has_next(&it)){
134         avdtp_stream_endpoint_t * stream_endpoint = (avdtp_stream_endpoint_t *)btstack_linked_list_iterator_next(&it);
135         if (stream_endpoint->sep.seid == seid){
136             return stream_endpoint;
137         }
138     }
139     return NULL;
140 }
141 
142 avdtp_connection_t * avdtp_get_connection_for_l2cap_signaling_cid(uint16_t l2cap_cid){
143     btstack_linked_list_iterator_t it;
144     btstack_linked_list_iterator_init(&it, &connections);
145     while (btstack_linked_list_iterator_has_next(&it)){
146         avdtp_connection_t * connection = (avdtp_connection_t *)btstack_linked_list_iterator_next(&it);
147         if (connection->l2cap_signaling_cid != l2cap_cid) continue;
148         return connection;
149     }
150     return NULL;
151 }
152 
153 static avdtp_stream_endpoint_t * avdtp_get_stream_endpoint_for_l2cap_cid(uint16_t l2cap_cid){
154     btstack_linked_list_iterator_t it;
155     btstack_linked_list_iterator_init(&it, avdtp_get_stream_endpoints());
156     while (btstack_linked_list_iterator_has_next(&it)){
157         avdtp_stream_endpoint_t * stream_endpoint = (avdtp_stream_endpoint_t *)btstack_linked_list_iterator_next(&it);
158         if (stream_endpoint->l2cap_media_cid == l2cap_cid){
159             return stream_endpoint;
160         }
161         if (stream_endpoint->l2cap_reporting_cid == l2cap_cid){
162             return stream_endpoint;
163         }
164         if (stream_endpoint->l2cap_recovery_cid == l2cap_cid){
165             return stream_endpoint;
166         }
167     }
168     return NULL;
169 }
170 
171 static avdtp_stream_endpoint_t * avdtp_get_stream_endpoint_for_signaling_cid(uint16_t l2cap_cid){
172     btstack_linked_list_iterator_t it;
173     btstack_linked_list_iterator_init(&it, avdtp_get_stream_endpoints());
174     while (btstack_linked_list_iterator_has_next(&it)){
175         avdtp_stream_endpoint_t * stream_endpoint = (avdtp_stream_endpoint_t *)btstack_linked_list_iterator_next(&it);
176         if (stream_endpoint->connection){
177             if (stream_endpoint->connection->l2cap_signaling_cid == l2cap_cid){
178                 return stream_endpoint;
179             }
180         }
181     }
182     return NULL;
183 }
184 
185 uint16_t avdtp_get_next_transaction_label(void){
186     transaction_id_counter++;
187     if (transaction_id_counter == 16){
188         transaction_id_counter = 1;
189     }
190     return transaction_id_counter;
191 }
192 
193 static avdtp_connection_t * avdtp_create_connection(bd_addr_t remote_addr, uint16_t cid){
194     avdtp_connection_t * connection = btstack_memory_avdtp_connection_get();
195     if (!connection){
196         log_error("Not enough memory to create connection");
197         return NULL;
198     }
199     connection->state = AVDTP_SIGNALING_CONNECTION_IDLE;
200     connection->initiator_transaction_label = avdtp_get_next_transaction_label();
201     connection->configuration_state = AVDTP_CONFIGURATION_STATE_IDLE;
202     connection->a2dp_source_discover_seps = false;
203     connection->avdtp_cid = cid;
204     (void)memcpy(connection->remote_addr, remote_addr, 6);
205 
206     btstack_linked_list_add(&connections, (btstack_linked_item_t *) connection);
207     return connection;
208 }
209 
210 static uint16_t avdtp_get_next_cid(void){
211     if (avdtp_cid_counter == 0xffff) {
212         avdtp_cid_counter = 1;
213     } else {
214         avdtp_cid_counter++;
215     }
216     return avdtp_cid_counter;
217 }
218 
219 static uint16_t avdtp_get_next_local_seid(void){
220     if (stream_endpoints_id_counter == 0xffff) {
221         stream_endpoints_id_counter = 1;
222     } else {
223         stream_endpoints_id_counter++;
224     }
225     return stream_endpoints_id_counter;
226 }
227 
228 static void avdtp_handle_start_sdp_client_query(void * context){
229     UNUSED(context);
230 
231     btstack_linked_list_iterator_t it;
232     btstack_linked_list_iterator_init(&it, &connections);
233     while (btstack_linked_list_iterator_has_next(&it)){
234         avdtp_connection_t * connection = (avdtp_connection_t *)btstack_linked_list_iterator_next(&it);
235 
236         switch (connection->state){
237             case AVDTP_SIGNALING_W2_SEND_SDP_QUERY_FOR_REMOTE_SOURCE:
238                 connection->state = AVDTP_SIGNALING_W4_SDP_QUERY_FOR_REMOTE_SOURCE_COMPLETE;
239                 break;
240             case AVDTP_SIGNALING_W2_SEND_SDP_QUERY_FOR_REMOTE_SINK:
241                 connection->state = AVDTP_SIGNALING_W4_SDP_QUERY_FOR_REMOTE_SINK_COMPLETE;
242                 break;
243             case AVDTP_SIGNALING_CONNECTION_OPENED:
244                 if (connection->initiator_connection_state != AVDTP_SIGNALING_CONNECTION_INITIATOR_W2_SEND_SDP_QUERY_THEN_GET_ALL_CAPABILITIES) continue;
245                 connection->initiator_connection_state = AVDTP_SIGNALING_CONNECTION_INITIATOR_W4_SDP_QUERY_COMPLETE_THEN_GET_ALL_CAPABILITIES;
246                 break;
247             default:
248                 continue;
249         }
250         sdp_query_context_avdtp_cid = connection->avdtp_cid;
251         sdp_client_query_uuid16(&avdtp_handle_sdp_client_query_result, (uint8_t *) connection->remote_addr, BLUETOOTH_PROTOCOL_AVDTP);
252         return;
253     }
254 }
255 
256 uint8_t avdtp_connect(bd_addr_t remote, avdtp_role_t role, uint16_t * avdtp_cid){
257     avdtp_connection_t * connection = avdtp_get_connection_for_bd_addr(remote);
258     if (connection){
259         return ERROR_CODE_COMMAND_DISALLOWED;
260     }
261 
262     uint16_t cid = avdtp_get_next_cid();
263     if (avdtp_cid != NULL) {
264         *avdtp_cid = cid;
265     }
266 
267     connection = avdtp_create_connection(remote, cid);
268     if (!connection) return BTSTACK_MEMORY_ALLOC_FAILED;
269 
270     connection->avdtp_cid = cid;
271 
272     connection->avdtp_l2cap_psm = 0;
273     connection->avdtp_version  = 0;
274     connection->sink_supported = false;
275     connection->source_supported = false;
276 
277     switch (role){
278         case AVDTP_ROLE_SOURCE:
279             connection->state = AVDTP_SIGNALING_W2_SEND_SDP_QUERY_FOR_REMOTE_SINK;
280             break;
281         case AVDTP_ROLE_SINK:
282             connection->state = AVDTP_SIGNALING_W2_SEND_SDP_QUERY_FOR_REMOTE_SOURCE;
283             break;
284         default:
285             btstack_assert(false);
286             return ERROR_CODE_COMMAND_DISALLOWED;
287     }
288 
289     avdtp_handle_sdp_client_query_request.callback = &avdtp_handle_start_sdp_client_query;
290     // ignore ERROR_CODE_COMMAND_DISALLOWED because in that case, we already have requested an SDP callback
291     (void) sdp_client_register_query_callback(&avdtp_handle_sdp_client_query_request);
292     return ERROR_CODE_SUCCESS;
293 }
294 
295 
296 void avdtp_register_sink_packet_handler(btstack_packet_handler_t callback){
297     btstack_assert(callback != NULL);
298     avdtp_sink_callback = callback;
299 }
300 
301 void avdtp_register_source_packet_handler(btstack_packet_handler_t callback){
302     btstack_assert(callback != NULL);
303     avdtp_source_callback = callback;
304 }
305 
306 void avdtp_register_media_transport_category(avdtp_stream_endpoint_t * stream_endpoint){
307     if (!stream_endpoint){
308         log_error("Stream endpoint with given seid is not registered.");
309         return;
310     }
311     uint16_t bitmap = store_bit16(stream_endpoint->sep.registered_service_categories, AVDTP_MEDIA_TRANSPORT, 1);
312     stream_endpoint->sep.registered_service_categories = bitmap;
313 }
314 
315 void avdtp_register_reporting_category(avdtp_stream_endpoint_t * stream_endpoint){
316     if (!stream_endpoint){
317         log_error("Stream endpoint with given seid is not registered.");
318         return;
319     }
320     uint16_t bitmap = store_bit16(stream_endpoint->sep.registered_service_categories, AVDTP_REPORTING, 1);
321     stream_endpoint->sep.registered_service_categories = bitmap;
322 }
323 
324 void avdtp_register_delay_reporting_category(avdtp_stream_endpoint_t * stream_endpoint){
325     if (!stream_endpoint){
326         log_error("Stream endpoint with given seid is not registered.");
327         return;
328     }
329     uint16_t bitmap = store_bit16(stream_endpoint->sep.registered_service_categories, AVDTP_DELAY_REPORTING, 1);
330     stream_endpoint->sep.registered_service_categories = bitmap;
331 }
332 
333 void avdtp_register_recovery_category(avdtp_stream_endpoint_t * stream_endpoint, uint8_t maximum_recovery_window_size, uint8_t maximum_number_media_packets){
334     if (!stream_endpoint){
335         log_error("Stream endpoint with given seid is not registered.");
336         return;
337     }
338     uint16_t bitmap = store_bit16(stream_endpoint->sep.registered_service_categories, AVDTP_RECOVERY, 1);
339     stream_endpoint->sep.registered_service_categories = bitmap;
340     stream_endpoint->sep.capabilities.recovery.recovery_type = 0x01; // 0x01 = RFC2733
341     stream_endpoint->sep.capabilities.recovery.maximum_recovery_window_size = maximum_recovery_window_size;
342     stream_endpoint->sep.capabilities.recovery.maximum_number_media_packets = maximum_number_media_packets;
343 }
344 
345 void avdtp_register_content_protection_category(avdtp_stream_endpoint_t * stream_endpoint, uint16_t cp_type, const uint8_t * cp_type_value, uint8_t cp_type_value_len){
346     if (!stream_endpoint){
347         log_error("Stream endpoint with given seid is not registered.");
348         return;
349     }
350     uint16_t bitmap = store_bit16(stream_endpoint->sep.registered_service_categories, AVDTP_CONTENT_PROTECTION, 1);
351     stream_endpoint->sep.registered_service_categories = bitmap;
352     stream_endpoint->sep.capabilities.content_protection.cp_type = cp_type;
353     (void)memcpy(stream_endpoint->sep.capabilities.content_protection.cp_type_value,
354                  cp_type_value,
355                  btstack_min(cp_type_value_len, AVDTP_MAX_CONTENT_PROTECTION_TYPE_VALUE_LEN));
356     stream_endpoint->sep.capabilities.content_protection.cp_type_value_len = btstack_min(cp_type_value_len, AVDTP_MAX_CONTENT_PROTECTION_TYPE_VALUE_LEN);
357 }
358 
359 void avdtp_register_header_compression_category(avdtp_stream_endpoint_t * stream_endpoint, uint8_t back_ch, uint8_t media, uint8_t recovery){
360     if (!stream_endpoint){
361         log_error("Stream endpoint with given seid is not registered.");
362         return;
363     }
364     uint16_t bitmap = store_bit16(stream_endpoint->sep.registered_service_categories, AVDTP_HEADER_COMPRESSION, 1);
365     stream_endpoint->sep.registered_service_categories = bitmap;
366     stream_endpoint->sep.capabilities.header_compression.back_ch = back_ch;
367     stream_endpoint->sep.capabilities.header_compression.media = media;
368     stream_endpoint->sep.capabilities.header_compression.recovery = recovery;
369 }
370 
371 void avdtp_register_media_codec_category(avdtp_stream_endpoint_t * stream_endpoint, avdtp_media_type_t media_type, avdtp_media_codec_type_t media_codec_type, uint8_t * media_codec_info, uint16_t media_codec_info_len){
372     if (!stream_endpoint){
373         log_error("Stream endpoint with given seid is not registered.");
374         return;
375     }
376     uint16_t bitmap = store_bit16(stream_endpoint->sep.registered_service_categories, AVDTP_MEDIA_CODEC, 1);
377     stream_endpoint->sep.registered_service_categories = bitmap;
378     stream_endpoint->sep.capabilities.media_codec.media_type = media_type;
379     stream_endpoint->sep.capabilities.media_codec.media_codec_type = media_codec_type;
380     stream_endpoint->sep.capabilities.media_codec.media_codec_information = media_codec_info;
381     stream_endpoint->sep.capabilities.media_codec.media_codec_information_len = media_codec_info_len;
382 }
383 
384 void avdtp_register_multiplexing_category(avdtp_stream_endpoint_t * stream_endpoint, uint8_t fragmentation){
385     if (!stream_endpoint){
386         log_error("Stream endpoint with given seid is not registered.");
387         return;
388     }
389     uint16_t bitmap = store_bit16(stream_endpoint->sep.registered_service_categories, AVDTP_MULTIPLEXING, 1);
390     stream_endpoint->sep.registered_service_categories = bitmap;
391     stream_endpoint->sep.capabilities.multiplexing_mode.fragmentation = fragmentation;
392 }
393 
394 void avdtp_register_media_handler(void (*callback)(uint8_t local_seid, uint8_t *packet, uint16_t size)){
395     avdtp_sink_handle_media_data = callback;
396 }
397 
398 /* START: tracking can send now requests per l2cap cid */
399 static void avdtp_handle_can_send_now(uint16_t l2cap_cid) {
400 
401 	log_debug("avdtp_packet_handler, L2CAP_EVENT_CAN_SEND_NOW l2cap_cid 0x%02x", l2cap_cid);
402 
403 	// get signaling connection for l2cap cid
404 	avdtp_connection_t * connection = avdtp_get_connection_for_l2cap_signaling_cid(l2cap_cid);
405 
406 	if (connection != NULL) {
407 		if (connection->wait_to_send_acceptor) {
408 			log_debug("call avdtp_acceptor_stream_config_subsm_run %p", connection);
409 			connection->wait_to_send_acceptor = false;
410 			avdtp_acceptor_stream_config_subsm_run(connection);
411 		} else if (connection->wait_to_send_initiator) {
412 			log_debug("call avdtp_initiator_stream_config_subsm_handle_can_send_now_signaling %p", connection);
413 			connection->wait_to_send_initiator = false;
414 			avdtp_initiator_stream_config_subsm_handle_can_send_now_signaling(connection);
415 		}
416 		bool more_to_send = connection->wait_to_send_acceptor || connection->wait_to_send_initiator;
417 		if (more_to_send){
418 			l2cap_request_can_send_now_event(l2cap_cid);
419 		}
420 		return;
421 	}
422 
423 	// get stream endpoint connection for l2cap cid
424 	avdtp_stream_endpoint_t * stream_endpoint = avdtp_get_stream_endpoint_for_l2cap_cid(l2cap_cid);
425 	if (stream_endpoint != NULL) {
426 		log_debug("call avdtp_initiator_stream_config_subsm_handle_can_send_now_stream_endpoint %p", stream_endpoint);
427 		if (stream_endpoint->request_can_send_now) {
428 			stream_endpoint->request_can_send_now = 0;
429 			avdtp_initiator_stream_config_subsm_handle_can_send_now_stream_endpoint(stream_endpoint);
430 		}
431 		bool more_to_send = stream_endpoint->request_can_send_now != 0;
432 		if (more_to_send){
433 			l2cap_request_can_send_now_event(l2cap_cid);
434 		}
435 	}
436 }
437 /* END: tracking can send now requests per l2cap cid */
438 
439 
440 avdtp_stream_endpoint_t * avdtp_create_stream_endpoint(avdtp_sep_type_t sep_type, avdtp_media_type_t media_type){
441     avdtp_stream_endpoint_t * stream_endpoint = btstack_memory_avdtp_stream_endpoint_get();
442     if (!stream_endpoint){
443         log_error("Not enough memory to create stream endpoint");
444         return NULL;
445     }
446     stream_endpoint->sep.seid = avdtp_get_next_local_seid();
447     stream_endpoint->sep.media_type = media_type;
448     stream_endpoint->sep.type = sep_type;
449     btstack_linked_list_add(avdtp_get_stream_endpoints(), (btstack_linked_item_t *) stream_endpoint);
450     return stream_endpoint;
451 }
452 
453 void avdtp_finalize_stream_endpoint(avdtp_stream_endpoint_t * stream_endpoint){
454     btstack_linked_list_remove(avdtp_get_stream_endpoints(), (btstack_linked_item_t* ) stream_endpoint);
455     btstack_memory_avdtp_stream_endpoint_free(stream_endpoint);
456 }
457 
458 static void
459 handle_l2cap_data_packet_for_signaling_connection(avdtp_connection_t *connection, uint8_t *packet, uint16_t size) {
460     if (size < 2) return;
461 
462     uint16_t offset;
463     avdtp_message_type_t message_type = avdtp_get_signaling_packet_type(packet);
464     switch (message_type){
465         case AVDTP_CMD_MSG:
466             offset = avdtp_read_signaling_header(&connection->acceptor_signaling_packet, packet, size);
467             avdtp_acceptor_stream_config_subsm(connection, packet, size, offset);
468             break;
469         default:
470             offset = avdtp_read_signaling_header(&connection->initiator_signaling_packet, packet, size);
471             avdtp_initiator_stream_config_subsm(connection, packet, size, offset);
472             break;
473     }
474 }
475 
476 static void avdtp_handle_sdp_client_query_attribute_value(avdtp_connection_t * connection, uint8_t *packet){
477     des_iterator_t des_list_it;
478     des_iterator_t prot_it;
479 
480     // Handle new SDP record
481     if (sdp_event_query_attribute_byte_get_record_id(packet) != record_id) {
482         record_id = sdp_event_query_attribute_byte_get_record_id(packet);
483         // log_info("SDP Record: Nr: %d", record_id);
484     }
485 
486     if (sdp_event_query_attribute_byte_get_attribute_length(packet) <= attribute_value_buffer_size) {
487         attribute_value[sdp_event_query_attribute_byte_get_data_offset(packet)] = sdp_event_query_attribute_byte_get_data(packet);
488 
489         if ((uint16_t)(sdp_event_query_attribute_byte_get_data_offset(packet)+1) == sdp_event_query_attribute_byte_get_attribute_length(packet)) {
490 
491             switch(sdp_event_query_attribute_byte_get_attribute_id(packet)) {
492 
493                 case BLUETOOTH_ATTRIBUTE_SERVICE_CLASS_ID_LIST:
494                     if (de_get_element_type(attribute_value) != DE_DES) break;
495                     for (des_iterator_init(&des_list_it, attribute_value); des_iterator_has_more(&des_list_it); des_iterator_next(&des_list_it)) {
496                         uint8_t * element = des_iterator_get_element(&des_list_it);
497                         if (de_get_element_type(element) != DE_UUID) continue;
498                         uint32_t uuid = de_get_uuid32(element);
499                         switch (uuid){
500                             case BLUETOOTH_SERVICE_CLASS_AUDIO_SOURCE:
501                                 connection->source_supported = true;
502                                 log_info("source_supported");
503                                 break;
504                             case BLUETOOTH_SERVICE_CLASS_AUDIO_SINK:
505                                 connection->sink_supported = true;
506                                 log_info("sink_supported");
507                                 break;
508                             default:
509                                 break;
510                         }
511                     }
512                     break;
513 
514                 case BLUETOOTH_ATTRIBUTE_PROTOCOL_DESCRIPTOR_LIST:
515                     // log_info("SDP Attribute: 0x%04x", sdp_event_query_attribute_byte_get_attribute_id(packet));
516                     for (des_iterator_init(&des_list_it, attribute_value); des_iterator_has_more(&des_list_it); des_iterator_next(&des_list_it)) {
517                         uint8_t       *des_element;
518                         uint8_t       *element;
519                         uint32_t       uuid;
520 
521                         if (des_iterator_get_type(&des_list_it) != DE_DES) continue;
522 
523                         des_element = des_iterator_get_element(&des_list_it);
524                         des_iterator_init(&prot_it, des_element);
525                         element = des_iterator_get_element(&prot_it);
526 
527                         if (de_get_element_type(element) != DE_UUID) continue;
528 
529                         uuid = de_get_uuid32(element);
530                         des_iterator_next(&prot_it);
531                         // we assume that the even if there are both roles supported, remote device uses the same psm and avdtp version for both
532                         switch (uuid){
533                             case BLUETOOTH_PROTOCOL_L2CAP:
534                                 if (!des_iterator_has_more(&prot_it)) continue;
535                                 de_element_get_uint16(des_iterator_get_element(&prot_it), &connection->avdtp_l2cap_psm);
536                                 break;
537                             case BLUETOOTH_PROTOCOL_AVDTP:
538                                 if (!des_iterator_has_more(&prot_it)) continue;
539                                 de_element_get_uint16(des_iterator_get_element(&prot_it), &connection->avdtp_version);
540                                 log_info("avdtp version 0x%02x", connection->avdtp_version);
541                                 break;
542                             default:
543                                 break;
544                         }
545                     }
546                     break;
547 
548                 default:
549                     break;
550             }
551         }
552     } else {
553         log_error("SDP attribute value buffer size exceeded: available %d, required %d", attribute_value_buffer_size, sdp_event_query_attribute_byte_get_attribute_length(packet));
554     }
555 
556 }
557 
558 static void avdtp_finalize_connection(avdtp_connection_t * connection){
559     btstack_run_loop_remove_timer(&connection->retry_timer);
560     btstack_linked_list_remove(&connections, (btstack_linked_item_t*) connection);
561     btstack_memory_avdtp_connection_free(connection);
562 }
563 
564 static void avdtp_handle_sdp_query_failed(avdtp_connection_t * connection, uint8_t status){
565     switch (connection->state){
566         case AVDTP_SIGNALING_W4_SDP_QUERY_FOR_REMOTE_SINK_COMPLETE:
567         case AVDTP_SIGNALING_W4_SDP_QUERY_FOR_REMOTE_SOURCE_COMPLETE:
568             avdtp_signaling_emit_connection_established(connection->avdtp_cid, connection->remote_addr, connection->con_handle, status);
569             break;
570 
571         case AVDTP_SIGNALING_CONNECTION_OPENED:
572             // SDP query failed: try query that must be supported
573             connection->initiator_connection_state = AVDTP_SIGNALING_CONNECTION_INITIATOR_W2_GET_CAPABILITIES;
574 			avdtp_request_can_send_now_initiator(connection);
575             return;
576 
577         default:
578             btstack_assert(false);
579             break;
580     }
581     avdtp_finalize_connection(connection);
582     sdp_query_context_avdtp_cid = 0;
583     log_info("SDP query failed with status 0x%02x.", status);
584 }
585 
586 static void avdtp_handle_sdp_query_succeeded(avdtp_connection_t * connection){
587     log_info("avdtp_handle_sdp_query_succeeded: state %d", connection->state);
588 
589     switch (connection->state){
590         case AVDTP_SIGNALING_CONNECTION_OPENED:
591             if (connection->avdtp_version < 0x0103){
592                 connection->initiator_connection_state = AVDTP_SIGNALING_CONNECTION_INITIATOR_W2_GET_CAPABILITIES;
593             } else {
594                 connection->initiator_connection_state = AVDTP_SIGNALING_CONNECTION_INITIATOR_W2_GET_ALL_CAPABILITIES;
595             }
596 			avdtp_request_can_send_now_initiator(connection);
597             break;
598         default:
599             connection->state = AVDTP_SIGNALING_CONNECTION_W4_L2CAP_CONNECTED;
600             l2cap_create_channel(avdtp_packet_handler, connection->remote_addr, connection->avdtp_l2cap_psm, l2cap_max_mtu(), NULL);
601             break;
602     }
603 }
604 
605 static void avdtp_handle_sdp_client_query_result(uint8_t packet_type, uint16_t channel, uint8_t *packet, uint16_t size){
606     UNUSED(packet_type);
607     UNUSED(channel);
608     UNUSED(size);
609 
610     avdtp_connection_t * connection = avdtp_get_connection_for_avdtp_cid(sdp_query_context_avdtp_cid);
611     if (!connection) {
612         log_error("SDP query, connection with 0x%02x cid not found", sdp_query_context_avdtp_cid);
613         return;
614     }
615 
616     uint8_t status = ERROR_CODE_SUCCESS;
617     switch (connection->state){
618         case AVDTP_SIGNALING_W4_SDP_QUERY_FOR_REMOTE_SINK_COMPLETE:
619             switch (hci_event_packet_get_type(packet)){
620                 case SDP_EVENT_QUERY_ATTRIBUTE_VALUE:
621                     avdtp_handle_sdp_client_query_attribute_value(connection, packet);
622                     return;
623                 case SDP_EVENT_QUERY_COMPLETE:
624                     status = sdp_event_query_complete_get_status(packet);
625                     if (status != ERROR_CODE_SUCCESS) break;
626                     if (!connection->sink_supported || (connection->avdtp_l2cap_psm == 0)) {
627                         status = SDP_SERVICE_NOT_FOUND;
628                         break;
629                     }
630                     break;
631                 default:
632                     btstack_assert(false);
633                     return;
634             }
635             break;
636         case AVDTP_SIGNALING_W4_SDP_QUERY_FOR_REMOTE_SOURCE_COMPLETE:
637             switch (hci_event_packet_get_type(packet)){
638                 case SDP_EVENT_QUERY_ATTRIBUTE_VALUE:
639                     avdtp_handle_sdp_client_query_attribute_value(connection, packet);
640                     return;
641                 case SDP_EVENT_QUERY_COMPLETE:
642                     status = sdp_event_query_complete_get_status(packet);
643                     if (status != ERROR_CODE_SUCCESS) break;
644                     if (!connection->source_supported || (connection->avdtp_l2cap_psm == 0)) {
645                         status = SDP_SERVICE_NOT_FOUND;
646                         break;
647                     }
648                     break;
649                 default:
650                     btstack_assert(false);
651                     return;
652             }
653             break;
654 
655         case AVDTP_SIGNALING_CONNECTION_OPENED:
656             switch (hci_event_packet_get_type(packet)){
657                 case SDP_EVENT_QUERY_ATTRIBUTE_VALUE:
658                     avdtp_handle_sdp_client_query_attribute_value(connection, packet);
659                     return;
660                 case SDP_EVENT_QUERY_COMPLETE:
661                     // without suitable SDP Record, avdtp version v0.0 is assumed
662                     status = sdp_event_query_complete_get_status(packet);
663                     break;
664                 default:
665                     btstack_assert(false);
666                     return;
667             }
668             break;
669 
670         default:
671             // bail out, we must have had an incoming connection in the meantime; just trigger next sdp query on complete
672             if (hci_event_packet_get_type(packet) == SDP_EVENT_QUERY_COMPLETE){
673                 (void) sdp_client_register_query_callback(&avdtp_handle_sdp_client_query_request);
674             }
675             return;
676     }
677 
678     if (status == ERROR_CODE_SUCCESS){
679         avdtp_handle_sdp_query_succeeded(connection);
680     } else {
681         avdtp_handle_sdp_query_failed(connection, status);
682     }
683 
684     // register the SDP Query request to check if there is another connection waiting for the query
685     // ignore ERROR_CODE_COMMAND_DISALLOWED because in that case, we already have requested an SDP callback
686     (void) sdp_client_register_query_callback(&avdtp_handle_sdp_client_query_request);
687 }
688 
689 static avdtp_connection_t * avdtp_handle_incoming_connection(avdtp_connection_t * connection, bd_addr_t event_addr, hci_con_handle_t con_handle, uint16_t local_cid){
690     if (connection == NULL){
691         uint16_t cid = avdtp_get_next_cid();
692         connection = avdtp_create_connection(event_addr, cid);
693     }
694 
695     if (connection) {
696         connection->state = AVDTP_SIGNALING_CONNECTION_W4_L2CAP_CONNECTED;
697         connection->l2cap_signaling_cid = local_cid;
698         connection->con_handle = con_handle;
699         btstack_run_loop_remove_timer(&connection->retry_timer);
700     }
701     return connection;
702 }
703 
704 static void avdtp_retry_timer_timeout_handler(btstack_timer_source_t * timer){
705     uint16_t avdtp_cid = (uint16_t)(uintptr_t) btstack_run_loop_get_timer_context(timer);
706 
707     avdtp_connection_t * connection = avdtp_get_connection_for_avdtp_cid(avdtp_cid);
708     if (connection == NULL) return;
709 
710     if (connection->state == AVDTP_SIGNALING_CONNECTION_W2_L2CAP_RETRY){
711         connection->state = AVDTP_SIGNALING_CONNECTION_W4_L2CAP_CONNECTED;
712         l2cap_create_channel(&avdtp_packet_handler, connection->remote_addr, connection->avdtp_l2cap_psm, l2cap_max_mtu(), NULL);
713     }
714 }
715 
716 static void avdtp_retry_timer_start(avdtp_connection_t * connection){
717     btstack_run_loop_set_timer_handler(&connection->retry_timer, avdtp_retry_timer_timeout_handler);
718     btstack_run_loop_set_timer_context(&connection->retry_timer, (void *)(uintptr_t)connection->avdtp_cid);
719 
720     // add some jitter/randomness to reconnect delay
721     uint32_t timeout = 100 + (btstack_run_loop_get_time_ms() & 0x7F);
722     btstack_run_loop_set_timer(&connection->retry_timer, timeout);
723     btstack_run_loop_add_timer(&connection->retry_timer);
724 }
725 
726 
727 void avdtp_packet_handler(uint8_t packet_type, uint16_t channel, uint8_t *packet, uint16_t size){
728     bd_addr_t event_addr;
729     uint16_t psm;
730     uint16_t local_cid;
731     uint8_t  status;
732     uint16_t l2cap_mtu;
733     hci_con_handle_t con_handle;
734 
735     bool accept_streaming_connection;
736     bool outoing_signaling_active;
737     bool decline_connection;
738 
739     avdtp_stream_endpoint_t * stream_endpoint = NULL;
740     avdtp_connection_t * connection = NULL;
741 
742     switch (packet_type) {
743         case L2CAP_DATA_PACKET:
744             connection = avdtp_get_connection_for_l2cap_signaling_cid(channel);
745             if (connection){
746                 handle_l2cap_data_packet_for_signaling_connection(connection, packet, size);
747                 break;
748             }
749 
750             stream_endpoint = avdtp_get_stream_endpoint_for_l2cap_cid(channel);
751             if (!stream_endpoint){
752                 if (!connection) break;
753                 handle_l2cap_data_packet_for_signaling_connection(connection, packet, size);
754                 break;
755             }
756 
757             if (stream_endpoint->connection){
758                 if (channel == stream_endpoint->connection->l2cap_signaling_cid){
759                     handle_l2cap_data_packet_for_signaling_connection(stream_endpoint->connection, packet, size);
760                     break;
761                 }
762             }
763 
764             if (channel == stream_endpoint->l2cap_media_cid){
765                 btstack_assert(avdtp_sink_handle_media_data);
766                 (*avdtp_sink_handle_media_data)(avdtp_local_seid(stream_endpoint), packet, size);
767                 break;
768             }
769 
770             if (channel == stream_endpoint->l2cap_reporting_cid){
771                 log_info("L2CAP_DATA_PACKET for reporting: NOT IMPLEMENTED");
772             } else if (channel == stream_endpoint->l2cap_recovery_cid){
773                 log_info("L2CAP_DATA_PACKET for recovery: NOT IMPLEMENTED");
774             } else {
775                 log_error("avdtp packet handler L2CAP_DATA_PACKET: local cid 0x%02x not found", channel);
776             }
777             break;
778 
779         case HCI_EVENT_PACKET:
780             switch (hci_event_packet_get_type(packet)) {
781 
782                 case L2CAP_EVENT_INCOMING_CONNECTION:
783                     l2cap_event_incoming_connection_get_address(packet, event_addr);
784                     local_cid = l2cap_event_incoming_connection_get_local_cid(packet);
785                     con_handle = l2cap_event_incoming_connection_get_handle(packet);
786                     outoing_signaling_active = false;
787                     accept_streaming_connection = false;
788 
789                     connection = avdtp_get_connection_for_bd_addr(event_addr);
790                     if (connection != NULL){
791                         switch (connection->state){
792                             case AVDTP_SIGNALING_CONNECTION_W4_L2CAP_DISCONNECTED:
793                             case AVDTP_SIGNALING_CONNECTION_W4_L2CAP_CONNECTED:
794                                 outoing_signaling_active = true;
795                                 connection->incoming_declined = true;
796                                 break;
797                             case AVDTP_SIGNALING_CONNECTION_OPENED:
798                                 outoing_signaling_active = true;
799                                 accept_streaming_connection = true;
800                                 break;
801                             default:
802                                 break;
803                         }
804                     }
805                     log_info("incoming: %s, outoing_signaling_active %d, accept_streaming_connection %d",
806                         bd_addr_to_str(event_addr), outoing_signaling_active, accept_streaming_connection);
807 
808                     decline_connection = outoing_signaling_active && !accept_streaming_connection;
809                     if (outoing_signaling_active == false){
810                         connection = avdtp_handle_incoming_connection(connection, event_addr, con_handle, local_cid);
811                         if (connection == NULL){
812                             decline_connection = true;
813                         }
814                     } else if (accept_streaming_connection){
815                         if ((connection == NULL) || (connection->configuration_state != AVDTP_CONFIGURATION_STATE_REMOTE_CONFIGURED)) {
816                             decline_connection = true;
817                         } else {
818                             // now, we're only dealing with media connections that are created by remote side - we're acceptor here
819                             stream_endpoint = avdtp_get_stream_endpoint_for_seid(connection->acceptor_local_seid);
820                             if ((stream_endpoint == NULL) || (stream_endpoint->l2cap_media_cid != 0) ) {
821                                 decline_connection = true;
822                             }
823                         }
824                     }
825 
826                     if (decline_connection){
827                         l2cap_decline_connection(local_cid);
828                     } else {
829                         l2cap_accept_connection(local_cid);
830                     }
831                     break;
832 
833                 case L2CAP_EVENT_CHANNEL_OPENED:
834 
835                     psm = l2cap_event_channel_opened_get_psm(packet);
836                     if (psm != BLUETOOTH_PSM_AVDTP){
837                         log_info("Unexpected PSM - Not implemented yet, avdtp sink: L2CAP_EVENT_CHANNEL_OPENED ");
838                         return;
839                     }
840 
841                     status = l2cap_event_channel_opened_get_status(packet);
842                     // inform about new l2cap connection
843                     l2cap_event_channel_opened_get_address(packet, event_addr);
844                     local_cid = l2cap_event_channel_opened_get_local_cid(packet);
845                     l2cap_mtu = l2cap_event_channel_opened_get_remote_mtu(packet);
846                     connection = avdtp_get_connection_for_bd_addr(event_addr);
847                     if (connection == NULL){
848                         log_info("L2CAP_EVENT_CHANNEL_OPENED: no connection found for %s", bd_addr_to_str(event_addr));
849                         break;
850                     }
851 
852                     con_handle = l2cap_event_channel_opened_get_handle(packet);
853 
854                     switch (connection->state){
855                         case AVDTP_SIGNALING_CONNECTION_W4_L2CAP_CONNECTED:
856                             switch (status){
857                                 case ERROR_CODE_SUCCESS:
858                                     connection->l2cap_signaling_cid = local_cid;
859                                     connection->incoming_declined = false;
860                                     connection->l2cap_mtu = l2cap_mtu;
861                                     connection->con_handle = con_handle;
862                                     connection->state = AVDTP_SIGNALING_CONNECTION_OPENED;
863                                     log_info("Connection opened l2cap_signaling_cid 0x%02x, avdtp_cid 0x%02x, con_handle 0x%02x", connection->l2cap_signaling_cid, connection->avdtp_cid, con_handle);
864                                     avdtp_signaling_emit_connection_established(connection->avdtp_cid, event_addr, con_handle, status);
865                                     return;
866                                 case L2CAP_CONNECTION_RESPONSE_RESULT_REFUSED_RESOURCES:
867                                     if (connection->incoming_declined == true) {
868                                         log_info("Connection was declined, and the outgoing failed");
869                                         connection->state = AVDTP_SIGNALING_CONNECTION_W2_L2CAP_RETRY;
870                                         connection->incoming_declined = false;
871                                         avdtp_retry_timer_start(connection);
872                                         return;
873                                     }
874                                     break;
875                                 default:
876                                     log_info("Connection to %s failed. status code 0x%02x", bd_addr_to_str(event_addr), status);
877                                     break;
878                             }
879                             avdtp_signaling_emit_connection_established(connection->avdtp_cid, event_addr, con_handle, status);
880                             avdtp_finalize_connection(connection);
881                             break;
882 
883                         case AVDTP_SIGNALING_CONNECTION_OPENED:
884                             stream_endpoint = avdtp_get_stream_endpoint_for_signaling_cid(connection->l2cap_signaling_cid);
885                             if (!stream_endpoint){
886                                 log_info("L2CAP_EVENT_CHANNEL_OPENED: stream_endpoint not found for signaling cid 0x%02x", connection->l2cap_signaling_cid);
887                                 return;
888                             }
889                             if (status != ERROR_CODE_SUCCESS){
890                                 log_info("AVDTP_STREAM_ENDPOINT_OPENED failed with status %d, avdtp cid 0x%02x, l2cap_media_cid 0x%02x, local seid %d, remote seid %d", status, connection->avdtp_cid, stream_endpoint->l2cap_media_cid, avdtp_local_seid(stream_endpoint), avdtp_remote_seid(stream_endpoint));
891                                 stream_endpoint->state = AVDTP_STREAM_ENDPOINT_IDLE;
892                                 avdtp_streaming_emit_connection_established(stream_endpoint, status);
893                                 break;
894                             }
895                             switch (stream_endpoint->state){
896                                 case AVDTP_STREAM_ENDPOINT_W4_L2CAP_FOR_MEDIA_CONNECTED:
897                                     stream_endpoint->state = AVDTP_STREAM_ENDPOINT_OPENED;
898                                     stream_endpoint->l2cap_media_cid = l2cap_event_channel_opened_get_local_cid(packet);
899                                     stream_endpoint->media_con_handle = l2cap_event_channel_opened_get_handle(packet);
900 
901                                     log_info("AVDTP_STREAM_ENDPOINT_OPENED, avdtp cid 0x%02x, l2cap_media_cid 0x%02x, local seid %d, remote seid %d", connection->avdtp_cid, stream_endpoint->l2cap_media_cid, avdtp_local_seid(stream_endpoint), avdtp_remote_seid(stream_endpoint));
902                                     avdtp_streaming_emit_connection_established(stream_endpoint, ERROR_CODE_SUCCESS);
903                                     break;
904                                 default:
905                                     log_info("AVDTP_STREAM_ENDPOINT_OPENED failed - stream endpoint in wrong state %d, avdtp cid 0x%02x, l2cap_media_cid 0x%02x, local seid %d, remote seid %d", stream_endpoint->state, connection->avdtp_cid, stream_endpoint->l2cap_media_cid, avdtp_local_seid(stream_endpoint), avdtp_remote_seid(stream_endpoint));
906                                     avdtp_streaming_emit_connection_established(stream_endpoint, ERROR_CODE_COMMAND_DISALLOWED);
907                                     break;
908                             }
909                             break;
910 
911                         default:
912                             log_info("L2CAP connection to %s ignored: status code 0x%02x, connection state %d", bd_addr_to_str(event_addr), status, connection->state);
913                             break;
914                     }
915                     break;
916 
917                 case L2CAP_EVENT_CHANNEL_CLOSED:
918                     local_cid = l2cap_event_channel_closed_get_local_cid(packet);
919                     stream_endpoint = avdtp_get_stream_endpoint_for_l2cap_cid(local_cid);
920                     connection = avdtp_get_connection_for_l2cap_signaling_cid(local_cid);
921 
922                     log_info("Received L2CAP_EVENT_CHANNEL_CLOSED, cid 0x%2x, connection %p, stream_endpoint %p", local_cid, connection, stream_endpoint);
923 
924                     if (stream_endpoint){
925                         if (stream_endpoint->l2cap_media_cid == local_cid){
926                             connection = stream_endpoint->connection;
927                             if (connection) {
928                                 avdtp_streaming_emit_connection_released(stream_endpoint,
929                                                                          connection->avdtp_cid,
930                                                                          avdtp_local_seid(stream_endpoint));
931                             }
932                             avdtp_reset_stream_endpoint(stream_endpoint);
933                             connection->configuration_state = AVDTP_CONFIGURATION_STATE_IDLE;
934                             break;
935                         }
936                         if (stream_endpoint->l2cap_recovery_cid == local_cid){
937                             log_info("L2CAP_EVENT_CHANNEL_CLOSED recovery cid 0x%0x", local_cid);
938                             stream_endpoint->l2cap_recovery_cid = 0;
939                             break;
940                         }
941 
942                         if (stream_endpoint->l2cap_reporting_cid == local_cid){
943                             log_info("L2CAP_EVENT_CHANNEL_CLOSED reporting cid 0x%0x", local_cid);
944                             stream_endpoint->l2cap_reporting_cid = 0;
945                             break;
946                         }
947                     }
948 
949                     if (connection){
950                         btstack_linked_list_iterator_t it;
951                         btstack_linked_list_iterator_init(&it, avdtp_get_stream_endpoints());
952                         while (btstack_linked_list_iterator_has_next(&it)){
953                             stream_endpoint = (avdtp_stream_endpoint_t *)btstack_linked_list_iterator_next(&it);
954                             if (stream_endpoint->connection == connection){
955                                 avdtp_reset_stream_endpoint(stream_endpoint);
956                             }
957                         }
958                         avdtp_signaling_emit_connection_released(connection->avdtp_cid);
959                         avdtp_finalize_connection(connection);
960                         break;
961                     }
962                     break;
963 
964                 case L2CAP_EVENT_CAN_SEND_NOW:
965                     log_debug("avdtp_packet_handler, L2CAP_EVENT_CAN_SEND_NOW l2cap_cid 0x%02x", channel);
966 					avdtp_handle_can_send_now(channel);
967                     break;
968                 default:
969                     log_info("Unknown HCI event type %02x", hci_event_packet_get_type(packet));
970                     break;
971             }
972             break;
973 
974         default:
975             // other packet type
976             break;
977     }
978 }
979 
980 uint8_t avdtp_disconnect(uint16_t avdtp_cid){
981     avdtp_connection_t * connection = avdtp_get_connection_for_avdtp_cid(avdtp_cid);
982     if (!connection) return ERROR_CODE_UNKNOWN_CONNECTION_IDENTIFIER;
983 
984     if (connection->state == AVDTP_SIGNALING_CONNECTION_W4_L2CAP_DISCONNECTED) return ERROR_CODE_SUCCESS;
985 
986     btstack_linked_list_iterator_t it;
987     btstack_linked_list_iterator_init(&it, avdtp_get_stream_endpoints());
988 
989     while (btstack_linked_list_iterator_has_next(&it)){
990         avdtp_stream_endpoint_t * stream_endpoint = (avdtp_stream_endpoint_t *)btstack_linked_list_iterator_next(&it);
991         if (stream_endpoint->connection != connection) continue;
992 
993         switch (stream_endpoint->state){
994             case AVDTP_STREAM_ENDPOINT_OPENED:
995             case AVDTP_STREAM_ENDPOINT_STREAMING:
996                 stream_endpoint->state = AVDTP_STREAM_ENDPOINT_W4_L2CAP_FOR_MEDIA_DISCONNECTED;
997                 l2cap_disconnect(stream_endpoint->l2cap_media_cid, 0);
998                 break;
999             default:
1000                 break;
1001         }
1002     }
1003 
1004     connection->state = AVDTP_SIGNALING_CONNECTION_W4_L2CAP_DISCONNECTED;
1005     l2cap_disconnect(connection->l2cap_signaling_cid, 0);
1006     return ERROR_CODE_SUCCESS;
1007 }
1008 
1009 uint8_t avdtp_open_stream(uint16_t avdtp_cid, uint8_t local_seid, uint8_t remote_seid){
1010     avdtp_connection_t * connection = avdtp_get_connection_for_avdtp_cid(avdtp_cid);
1011     if (!connection){
1012         log_error("avdtp_media_connect: no connection for signaling cid 0x%02x found", avdtp_cid);
1013         return ERROR_CODE_UNKNOWN_CONNECTION_IDENTIFIER;
1014     }
1015 
1016     if (connection->state != AVDTP_SIGNALING_CONNECTION_OPENED) {
1017         log_error("avdtp_media_connect: wrong connection state %d", connection->state);
1018         return ERROR_CODE_COMMAND_DISALLOWED;
1019     }
1020 
1021     avdtp_stream_endpoint_t * stream_endpoint = avdtp_get_stream_endpoint_for_seid(local_seid);
1022     if (!stream_endpoint) {
1023         log_error("avdtp_media_connect: no stream_endpoint with seid %d found", local_seid);
1024         return ERROR_CODE_UNKNOWN_CONNECTION_IDENTIFIER;
1025     }
1026 
1027     if (stream_endpoint->remote_sep.seid != remote_seid){
1028         log_error("avdtp_media_connect: no remote sep with seid %d registered with the stream endpoint", remote_seid);
1029         return ERROR_CODE_UNKNOWN_CONNECTION_IDENTIFIER;
1030     }
1031 
1032     if (stream_endpoint->state < AVDTP_STREAM_ENDPOINT_CONFIGURED) return ERROR_CODE_COMMAND_DISALLOWED;
1033 
1034     connection->initiator_transaction_label= avdtp_get_next_transaction_label();
1035     connection->initiator_remote_seid = remote_seid;
1036     connection->initiator_local_seid = local_seid;
1037     stream_endpoint->initiator_config_state = AVDTP_INITIATOR_W2_OPEN_STREAM;
1038     stream_endpoint->state = AVDTP_STREAM_ENDPOINT_W2_REQUEST_OPEN_STREAM;
1039 	avdtp_request_can_send_now_initiator(connection);
1040     return ERROR_CODE_SUCCESS;
1041 }
1042 
1043 uint8_t avdtp_start_stream(uint16_t avdtp_cid, uint8_t local_seid){
1044     avdtp_connection_t * connection = avdtp_get_connection_for_avdtp_cid(avdtp_cid);
1045     if (!connection){
1046         log_error("avdtp_start_stream: no connection for signaling cid 0x%02x found", avdtp_cid);
1047         return ERROR_CODE_UNKNOWN_CONNECTION_IDENTIFIER;
1048     }
1049 
1050     avdtp_stream_endpoint_t * stream_endpoint = avdtp_get_stream_endpoint_for_seid(local_seid);
1051     if (!stream_endpoint) {
1052         log_error("avdtp_start_stream: no stream_endpoint with seid %d found", local_seid);
1053         return ERROR_CODE_UNKNOWN_CONNECTION_IDENTIFIER;
1054     }
1055 
1056     if (stream_endpoint->l2cap_media_cid == 0){
1057         log_error("avdtp_start_stream: no media connection for stream_endpoint with seid %d found", local_seid);
1058         return ERROR_CODE_UNKNOWN_CONNECTION_IDENTIFIER;
1059     }
1060 
1061     if (!is_avdtp_remote_seid_registered(stream_endpoint)){
1062         log_error("avdtp_media_connect: no remote sep registered with the stream endpoint");
1063         return ERROR_CODE_UNKNOWN_CONNECTION_IDENTIFIER;
1064     }
1065 
1066     if (!is_avdtp_remote_seid_registered(stream_endpoint) || stream_endpoint->start_stream == 1){
1067         return ERROR_CODE_COMMAND_DISALLOWED;
1068     }
1069 
1070     stream_endpoint->start_stream = 1;
1071     connection->initiator_local_seid = local_seid;
1072     connection->initiator_remote_seid = stream_endpoint->remote_sep.seid;
1073 	avdtp_request_can_send_now_initiator(connection);
1074     return ERROR_CODE_SUCCESS;
1075 }
1076 
1077 uint8_t avdtp_stop_stream(uint16_t avdtp_cid, uint8_t local_seid){
1078     avdtp_connection_t * connection = avdtp_get_connection_for_avdtp_cid(avdtp_cid);
1079     if (!connection){
1080         log_error("avdtp_stop_stream: no connection for signaling cid 0x%02x found", avdtp_cid);
1081         return ERROR_CODE_UNKNOWN_CONNECTION_IDENTIFIER;
1082     }
1083 
1084     avdtp_stream_endpoint_t * stream_endpoint = avdtp_get_stream_endpoint_for_seid(local_seid);
1085     if (!stream_endpoint) {
1086         log_error("avdtp_stop_stream: no stream_endpoint with seid %d found", local_seid);
1087         return ERROR_CODE_UNKNOWN_CONNECTION_IDENTIFIER;
1088     }
1089 
1090     if (stream_endpoint->l2cap_media_cid == 0){
1091         log_error("avdtp_stop_stream: no media connection for stream_endpoint with seid %d found", local_seid);
1092         return ERROR_CODE_UNKNOWN_CONNECTION_IDENTIFIER;
1093     }
1094 
1095     if (!is_avdtp_remote_seid_registered(stream_endpoint) || stream_endpoint->close_stream){
1096         return ERROR_CODE_COMMAND_DISALLOWED;
1097     }
1098 
1099     stream_endpoint->close_stream = 1;
1100     connection->initiator_local_seid = local_seid;
1101     connection->initiator_remote_seid = stream_endpoint->remote_sep.seid;
1102 	avdtp_request_can_send_now_initiator(connection);
1103     return ERROR_CODE_SUCCESS;
1104 }
1105 
1106 uint8_t avdtp_abort_stream(uint16_t avdtp_cid, uint8_t local_seid){
1107     avdtp_connection_t * connection = avdtp_get_connection_for_avdtp_cid(avdtp_cid);
1108     if (!connection){
1109         log_error("avdtp_abort_stream: no connection for signaling cid 0x%02x found", avdtp_cid);
1110         return ERROR_CODE_UNKNOWN_CONNECTION_IDENTIFIER;
1111     }
1112 
1113     avdtp_stream_endpoint_t * stream_endpoint = avdtp_get_stream_endpoint_for_seid(local_seid);
1114     if (!stream_endpoint) {
1115         log_error("avdtp_abort_stream: no stream_endpoint with seid %d found", local_seid);
1116         return ERROR_CODE_UNKNOWN_CONNECTION_IDENTIFIER;
1117     }
1118 
1119     if (stream_endpoint->l2cap_media_cid == 0){
1120         log_error("avdtp_abort_stream: no media connection for stream_endpoint with seid %d found", local_seid);
1121         return ERROR_CODE_UNKNOWN_CONNECTION_IDENTIFIER;
1122     }
1123 
1124     if (!is_avdtp_remote_seid_registered(stream_endpoint) || stream_endpoint->abort_stream){
1125         return ERROR_CODE_COMMAND_DISALLOWED;
1126     }
1127 
1128     stream_endpoint->abort_stream = 1;
1129     connection->initiator_local_seid = local_seid;
1130     connection->initiator_remote_seid = stream_endpoint->remote_sep.seid;
1131 	avdtp_request_can_send_now_initiator(connection);
1132     return ERROR_CODE_SUCCESS;
1133 }
1134 
1135 uint8_t avdtp_suspend_stream(uint16_t avdtp_cid, uint8_t local_seid){
1136     avdtp_connection_t * connection = avdtp_get_connection_for_avdtp_cid(avdtp_cid);
1137     if (!connection){
1138         log_error("avdtp_suspend_stream: no connection for signaling cid 0x%02x found", avdtp_cid);
1139         return ERROR_CODE_UNKNOWN_CONNECTION_IDENTIFIER;
1140     }
1141     avdtp_stream_endpoint_t * stream_endpoint = avdtp_get_stream_endpoint_for_seid(local_seid);
1142     if (!stream_endpoint) {
1143         log_error("avdtp_suspend_stream: no stream_endpoint with seid %d found", local_seid);
1144         return ERROR_CODE_UNKNOWN_CONNECTION_IDENTIFIER;
1145     }
1146 
1147     if (stream_endpoint->l2cap_media_cid == 0){
1148         log_error("avdtp_suspend_stream: no media connection for stream_endpoint with seid %d found", local_seid);
1149         return ERROR_CODE_UNKNOWN_CONNECTION_IDENTIFIER;
1150     }
1151 
1152     if (!is_avdtp_remote_seid_registered(stream_endpoint) || stream_endpoint->suspend_stream){
1153         return ERROR_CODE_COMMAND_DISALLOWED;
1154     }
1155 
1156     stream_endpoint->suspend_stream = 1;
1157     connection->initiator_local_seid = local_seid;
1158     connection->initiator_remote_seid = stream_endpoint->remote_sep.seid;
1159 	avdtp_request_can_send_now_initiator(connection);
1160     return ERROR_CODE_SUCCESS;
1161 }
1162 
1163 uint8_t avdtp_discover_stream_endpoints(uint16_t avdtp_cid){
1164     avdtp_connection_t * connection = avdtp_get_connection_for_avdtp_cid(avdtp_cid);
1165     if (!connection){
1166         log_error("avdtp_discover_stream_endpoints: no connection for signaling cid 0x%02x found", avdtp_cid);
1167         return ERROR_CODE_UNKNOWN_CONNECTION_IDENTIFIER;
1168     }
1169     if ((connection->state != AVDTP_SIGNALING_CONNECTION_OPENED) ||
1170         (connection->initiator_connection_state != AVDTP_SIGNALING_CONNECTION_INITIATOR_IDLE)) {
1171         return ERROR_CODE_COMMAND_DISALLOWED;
1172     }
1173 
1174     connection->initiator_transaction_label= avdtp_get_next_transaction_label();
1175     connection->initiator_connection_state = AVDTP_SIGNALING_CONNECTION_INITIATOR_W2_DISCOVER_SEPS;
1176     return avdtp_request_can_send_now_initiator(connection);
1177 }
1178 
1179 
1180 uint8_t avdtp_get_capabilities(uint16_t avdtp_cid, uint8_t remote_seid){
1181     avdtp_connection_t * connection = avdtp_get_connection_for_avdtp_cid(avdtp_cid);
1182     if (!connection){
1183         log_error("No connection for AVDTP cid 0x%02x found", avdtp_cid);
1184         return ERROR_CODE_UNKNOWN_CONNECTION_IDENTIFIER;
1185     }
1186     if ((connection->state != AVDTP_SIGNALING_CONNECTION_OPENED) ||
1187         (connection->initiator_connection_state != AVDTP_SIGNALING_CONNECTION_INITIATOR_IDLE)) {
1188         return ERROR_CODE_COMMAND_DISALLOWED;
1189     }
1190 
1191     connection->initiator_transaction_label= avdtp_get_next_transaction_label();
1192     connection->initiator_connection_state = AVDTP_SIGNALING_CONNECTION_INITIATOR_W2_GET_CAPABILITIES;
1193     connection->initiator_remote_seid = remote_seid;
1194     return avdtp_request_can_send_now_initiator(connection);
1195 }
1196 
1197 
1198 uint8_t avdtp_get_all_capabilities(uint16_t avdtp_cid, uint8_t remote_seid){
1199     avdtp_connection_t * connection = avdtp_get_connection_for_avdtp_cid(avdtp_cid);
1200     if (!connection){
1201         log_error("No connection for AVDTP cid 0x%02x found", avdtp_cid);
1202         return ERROR_CODE_UNKNOWN_CONNECTION_IDENTIFIER;
1203     }
1204     if ((connection->state != AVDTP_SIGNALING_CONNECTION_OPENED) ||
1205         (connection->initiator_connection_state != AVDTP_SIGNALING_CONNECTION_INITIATOR_IDLE)) {
1206         return ERROR_CODE_COMMAND_DISALLOWED;
1207     }
1208 
1209     connection->initiator_transaction_label= avdtp_get_next_transaction_label();
1210     connection->initiator_remote_seid = remote_seid;
1211 
1212     if (connection->avdtp_version == 0){
1213         connection->initiator_connection_state = AVDTP_SIGNALING_CONNECTION_INITIATOR_W2_SEND_SDP_QUERY_THEN_GET_ALL_CAPABILITIES;
1214         avdtp_handle_sdp_client_query_request.callback = &avdtp_handle_start_sdp_client_query;
1215         // ignore ERROR_CODE_COMMAND_DISALLOWED because in that case, we already have requested an SDP callback
1216         (void) sdp_client_register_query_callback(&avdtp_handle_sdp_client_query_request);
1217         return ERROR_CODE_SUCCESS;
1218     } else {
1219         // AVDTP version lower then 1.3 supports only get capabilities command
1220         if (connection->avdtp_version < 0x103){
1221             connection->initiator_connection_state = AVDTP_SIGNALING_CONNECTION_INITIATOR_W2_GET_CAPABILITIES;
1222         } else {
1223             connection->initiator_connection_state = AVDTP_SIGNALING_CONNECTION_INITIATOR_W2_GET_ALL_CAPABILITIES;
1224         }
1225         return avdtp_request_can_send_now_initiator(connection);
1226     }
1227 }
1228 
1229 uint8_t avdtp_get_configuration(uint16_t avdtp_cid, uint8_t remote_seid){
1230     avdtp_connection_t * connection = avdtp_get_connection_for_avdtp_cid(avdtp_cid);
1231     if (!connection){
1232         log_error("No connection for AVDTP cid 0x%02x found", avdtp_cid);
1233         return ERROR_CODE_UNKNOWN_CONNECTION_IDENTIFIER;
1234     }
1235     if ((connection->state != AVDTP_SIGNALING_CONNECTION_OPENED) ||
1236         (connection->initiator_connection_state != AVDTP_SIGNALING_CONNECTION_INITIATOR_IDLE)) {
1237         return ERROR_CODE_COMMAND_DISALLOWED;
1238     }
1239 
1240     connection->initiator_transaction_label= avdtp_get_next_transaction_label();
1241     connection->initiator_connection_state = AVDTP_SIGNALING_CONNECTION_INITIATOR_W2_GET_CONFIGURATION;
1242     connection->initiator_remote_seid = remote_seid;
1243     return avdtp_request_can_send_now_initiator(connection);
1244 }
1245 
1246 uint8_t avdtp_set_configuration(uint16_t avdtp_cid, uint8_t local_seid, uint8_t remote_seid, uint16_t configured_services_bitmap, avdtp_capabilities_t configuration){
1247     avdtp_connection_t * connection = avdtp_get_connection_for_avdtp_cid(avdtp_cid);
1248     if (!connection){
1249         log_error("No connection for AVDTP cid 0x%02x found", avdtp_cid);
1250         return ERROR_CODE_UNKNOWN_CONNECTION_IDENTIFIER;
1251     }
1252     if ((connection->state != AVDTP_SIGNALING_CONNECTION_OPENED) ||
1253         (connection->initiator_connection_state != AVDTP_SIGNALING_CONNECTION_INITIATOR_IDLE)) {
1254         log_error("connection in wrong state, %d, initiator state %d", connection->state, connection->initiator_connection_state);
1255         return ERROR_CODE_COMMAND_DISALLOWED;
1256     }
1257     if (connection->configuration_state != AVDTP_CONFIGURATION_STATE_IDLE){
1258         log_info("configuration already started, config state %u", connection->configuration_state);
1259         return ERROR_CODE_COMMAND_DISALLOWED;
1260     }
1261 
1262     avdtp_stream_endpoint_t * stream_endpoint = avdtp_get_stream_endpoint_for_seid(local_seid);
1263     if (!stream_endpoint) {
1264         log_error("No initiator stream endpoint for seid %d", local_seid);
1265         return ERROR_CODE_UNKNOWN_CONNECTION_IDENTIFIER;
1266     }
1267     if (stream_endpoint->state >= AVDTP_STREAM_ENDPOINT_CONFIGURED){
1268         log_error("Stream endpoint seid %d in wrong state %d", local_seid, stream_endpoint->state);
1269         return ERROR_CODE_COMMAND_DISALLOWED;
1270     }
1271 
1272     connection->active_stream_endpoint = (void*) stream_endpoint;
1273     connection->configuration_state = AVDTP_CONFIGURATION_STATE_LOCAL_INITIATED;
1274 
1275     connection->initiator_transaction_label= avdtp_get_next_transaction_label();
1276     connection->initiator_remote_seid = remote_seid;
1277     connection->initiator_local_seid = local_seid;
1278     stream_endpoint->remote_configuration_bitmap = configured_services_bitmap;
1279     stream_endpoint->remote_configuration = configuration;
1280     stream_endpoint->initiator_config_state = AVDTP_INITIATOR_W2_SET_CONFIGURATION;
1281 
1282 	log_debug("SE %p, initiator_config_state: 0x%02x", stream_endpoint, stream_endpoint->initiator_config_state);
1283 
1284     return avdtp_request_can_send_now_initiator(connection);
1285 }
1286 
1287 uint8_t avdtp_reconfigure(uint16_t avdtp_cid, uint8_t local_seid, uint8_t remote_seid, uint16_t configured_services_bitmap, avdtp_capabilities_t configuration){
1288     avdtp_connection_t * connection = avdtp_get_connection_for_avdtp_cid(avdtp_cid);
1289     if (!connection){
1290         log_error("No connection for AVDTP cid 0x%02x found", avdtp_cid);
1291         return ERROR_CODE_UNKNOWN_CONNECTION_IDENTIFIER;
1292     }
1293     //TODO: if opened only app capabilities, enable reconfigure for not opened
1294     if ((connection->state != AVDTP_SIGNALING_CONNECTION_OPENED) ||
1295         (connection->initiator_connection_state != AVDTP_SIGNALING_CONNECTION_INITIATOR_IDLE)) {
1296         return ERROR_CODE_COMMAND_DISALLOWED;
1297     }
1298 
1299     avdtp_stream_endpoint_t * stream_endpoint = avdtp_get_stream_endpoint_for_seid(local_seid);
1300     if (!stream_endpoint) {
1301         log_error("avdtp_reconfigure: no initiator stream endpoint for seid %d", local_seid);
1302         return ERROR_CODE_UNKNOWN_CONNECTION_IDENTIFIER;
1303     }
1304 
1305     if (!is_avdtp_remote_seid_registered(stream_endpoint)){
1306         log_error("avdtp_reconfigure: no associated remote sep");
1307         return ERROR_CODE_COMMAND_DISALLOWED;
1308     }
1309 
1310     connection->initiator_transaction_label= avdtp_get_next_transaction_label();
1311     connection->initiator_remote_seid = remote_seid;
1312     connection->initiator_local_seid = local_seid;
1313     stream_endpoint->remote_configuration_bitmap = configured_services_bitmap;
1314     stream_endpoint->remote_configuration = configuration;
1315     stream_endpoint->initiator_config_state = AVDTP_INITIATOR_W2_RECONFIGURE_STREAM_WITH_SEID;
1316     return avdtp_request_can_send_now_initiator(connection);
1317 }
1318 
1319 void    avdtp_set_preferred_sampling_frequeny(avdtp_stream_endpoint_t * stream_endpoint, uint32_t sampling_frequency){
1320     stream_endpoint->preferred_sampling_frequency = sampling_frequency;
1321 }
1322 
1323 void    avdtp_set_preferred_channel_mode(avdtp_stream_endpoint_t * stream_endpoint, uint8_t channel_mode){
1324     stream_endpoint->preferred_channel_mode = channel_mode;
1325 }
1326 
1327 
1328 uint8_t avdtp_choose_sbc_channel_mode(avdtp_stream_endpoint_t * stream_endpoint, uint8_t remote_channel_mode_bitmap){
1329     uint8_t * media_codec = stream_endpoint->sep.capabilities.media_codec.media_codec_information;
1330     uint8_t channel_mode_bitmap = (media_codec[0] & 0x0F) & remote_channel_mode_bitmap;
1331 
1332     uint8_t channel_mode = AVDTP_SBC_STEREO;
1333     // use preferred channel mode if possible
1334     if (stream_endpoint->preferred_channel_mode == AVDTP_SBC_JOINT_STEREO){
1335         return AVDTP_SBC_JOINT_STEREO;
1336     }
1337     if (stream_endpoint->preferred_channel_mode == AVDTP_SBC_STEREO){
1338         return AVDTP_SBC_STEREO;
1339     }
1340     if (stream_endpoint->preferred_channel_mode == AVDTP_SBC_DUAL_CHANNEL){
1341         return AVDTP_SBC_DUAL_CHANNEL;
1342     }
1343     if (stream_endpoint->preferred_channel_mode == AVDTP_SBC_MONO){
1344         return AVDTP_SBC_MONO;
1345     }
1346 
1347 
1348     if (channel_mode_bitmap & AVDTP_SBC_JOINT_STEREO){
1349         channel_mode = AVDTP_SBC_JOINT_STEREO;
1350     } else if (channel_mode_bitmap & AVDTP_SBC_STEREO){
1351         channel_mode = AVDTP_SBC_STEREO;
1352     } else if (channel_mode_bitmap & AVDTP_SBC_DUAL_CHANNEL){
1353         channel_mode = AVDTP_SBC_DUAL_CHANNEL;
1354     } else if (channel_mode_bitmap & AVDTP_SBC_MONO){
1355         channel_mode = AVDTP_SBC_MONO;
1356     }
1357     return channel_mode;
1358 }
1359 
1360 uint8_t avdtp_choose_sbc_allocation_method(avdtp_stream_endpoint_t * stream_endpoint, uint8_t remote_allocation_method_bitmap){
1361     uint8_t * media_codec = stream_endpoint->sep.capabilities.media_codec.media_codec_information;
1362     uint8_t allocation_method_bitmap = (media_codec[1] & 0x03) & remote_allocation_method_bitmap;
1363 
1364     uint8_t allocation_method = AVDTP_SBC_ALLOCATION_METHOD_LOUDNESS;
1365     if (allocation_method_bitmap & AVDTP_SBC_ALLOCATION_METHOD_LOUDNESS){
1366         allocation_method = AVDTP_SBC_ALLOCATION_METHOD_LOUDNESS;
1367     } else if (allocation_method_bitmap & AVDTP_SBC_ALLOCATION_METHOD_SNR){
1368         allocation_method = AVDTP_SBC_ALLOCATION_METHOD_SNR;
1369     }
1370     return allocation_method;
1371 }
1372 
1373 uint8_t avdtp_stream_endpoint_seid(avdtp_stream_endpoint_t * stream_endpoint){
1374     if (!stream_endpoint) return 0;
1375     return stream_endpoint->sep.seid;
1376 }
1377 uint8_t avdtp_choose_sbc_subbands(avdtp_stream_endpoint_t * stream_endpoint, uint8_t remote_subbands_bitmap){
1378     if (!stream_endpoint) return 0;
1379     uint8_t * media_codec = stream_endpoint->sep.capabilities.media_codec.media_codec_information;
1380     uint8_t subbands_bitmap = ((media_codec[1] >> 2) & 0x03) & remote_subbands_bitmap;
1381 
1382     uint8_t subbands = AVDTP_SBC_SUBBANDS_8;
1383     if (subbands_bitmap & AVDTP_SBC_SUBBANDS_8){
1384         subbands = AVDTP_SBC_SUBBANDS_8;
1385     } else if (subbands_bitmap & AVDTP_SBC_SUBBANDS_4){
1386         subbands = AVDTP_SBC_SUBBANDS_4;
1387     }
1388     return subbands;
1389 }
1390 
1391 uint8_t avdtp_choose_sbc_block_length(avdtp_stream_endpoint_t * stream_endpoint, uint8_t remote_block_length_bitmap){
1392     if (!stream_endpoint) return 0;
1393     uint8_t * media_codec = stream_endpoint->sep.capabilities.media_codec.media_codec_information;
1394     uint8_t block_length_bitmap = (media_codec[1] >> 4) & remote_block_length_bitmap;
1395 
1396     uint8_t block_length = AVDTP_SBC_BLOCK_LENGTH_16;
1397     if (block_length_bitmap & AVDTP_SBC_BLOCK_LENGTH_16){
1398         block_length = AVDTP_SBC_BLOCK_LENGTH_16;
1399     } else if (block_length_bitmap & AVDTP_SBC_BLOCK_LENGTH_12){
1400         block_length = AVDTP_SBC_BLOCK_LENGTH_12;
1401     } else if (block_length_bitmap & AVDTP_SBC_BLOCK_LENGTH_8){
1402         block_length = AVDTP_SBC_BLOCK_LENGTH_8;
1403     } else if (block_length_bitmap & AVDTP_SBC_BLOCK_LENGTH_4){
1404         block_length = AVDTP_SBC_BLOCK_LENGTH_4;
1405     }
1406     return block_length;
1407 }
1408 
1409 uint8_t avdtp_choose_sbc_sampling_frequency(avdtp_stream_endpoint_t * stream_endpoint, uint8_t remote_sampling_frequency_bitmap){
1410     if (!stream_endpoint) return 0;
1411     uint8_t * media_codec = stream_endpoint->sep.capabilities.media_codec.media_codec_information;
1412     uint8_t supported_sampling_frequency_bitmap = (media_codec[0] >> 4) & remote_sampling_frequency_bitmap;
1413 
1414     // use preferred sampling frequency if possible
1415     if ((stream_endpoint->preferred_sampling_frequency == 48000) && (supported_sampling_frequency_bitmap & AVDTP_SBC_48000)){
1416         return AVDTP_SBC_48000;
1417     }
1418     if ((stream_endpoint->preferred_sampling_frequency == 44100) && (supported_sampling_frequency_bitmap & AVDTP_SBC_44100)){
1419         return AVDTP_SBC_44100;
1420     }
1421     if ((stream_endpoint->preferred_sampling_frequency == 32000) && (supported_sampling_frequency_bitmap & AVDTP_SBC_32000)){
1422         return AVDTP_SBC_32000;
1423     }
1424     if ((stream_endpoint->preferred_sampling_frequency == 16000) && (supported_sampling_frequency_bitmap & AVDTP_SBC_16000)){
1425         return AVDTP_SBC_16000;
1426     }
1427 
1428     // otherwise, use highest available
1429     if (supported_sampling_frequency_bitmap & AVDTP_SBC_48000){
1430         return AVDTP_SBC_48000;
1431     }
1432     if (supported_sampling_frequency_bitmap & AVDTP_SBC_44100){
1433         return AVDTP_SBC_44100;
1434     }
1435     if (supported_sampling_frequency_bitmap & AVDTP_SBC_32000){
1436         return AVDTP_SBC_32000;
1437     }
1438     if (supported_sampling_frequency_bitmap & AVDTP_SBC_16000){
1439         return AVDTP_SBC_16000;
1440     }
1441     return AVDTP_SBC_44100; // some default
1442 }
1443 
1444 uint8_t avdtp_choose_sbc_max_bitpool_value(avdtp_stream_endpoint_t * stream_endpoint, uint8_t remote_max_bitpool_value){
1445     if (!stream_endpoint) return 0;
1446     uint8_t * media_codec = stream_endpoint->sep.capabilities.media_codec.media_codec_information;
1447     return btstack_min(media_codec[3], remote_max_bitpool_value);
1448 }
1449 
1450 uint8_t avdtp_choose_sbc_min_bitpool_value(avdtp_stream_endpoint_t * stream_endpoint, uint8_t remote_min_bitpool_value){
1451     if (!stream_endpoint) return 0;
1452     uint8_t * media_codec = stream_endpoint->sep.capabilities.media_codec.media_codec_information;
1453     return btstack_max(media_codec[2], remote_min_bitpool_value);
1454 }
1455 
1456 uint8_t is_avdtp_remote_seid_registered(avdtp_stream_endpoint_t * stream_endpoint){
1457     if (!stream_endpoint) return 0;
1458     if (stream_endpoint->remote_sep.seid == 0) return 0;
1459     if (stream_endpoint->remote_sep.seid > 0x3E) return 0;
1460     return 1;
1461 }
1462 
1463 void avdtp_init(void){
1464     static bool l2cap_registered = false;
1465     if (!l2cap_registered){
1466         l2cap_registered = true;
1467         l2cap_register_service(&avdtp_packet_handler, BLUETOOTH_PSM_AVDTP, 0xffff, gap_get_security_level());
1468     }
1469 }
1470