xref: /btstack/src/classic/avdtp_util.c (revision a8d51f092f1b660d0f6921369ad2bc3f9368296c)
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_util.c"
39 
40 #include <stdint.h>
41 #include <string.h>
42 
43 #include "btstack.h"
44 #include "avdtp.h"
45 #include "avdtp_util.h"
46 
47 #define MAX_MEDIA_CODEC_INFORMATION_LENGTH 100
48 
49 
50 /*
51 
52  List of AVDTP_SUBEVENTs sorted by packet handler
53 
54 
55 Sink + Source:
56 - AVDTP_SUBEVENT_SIGNALING_CONNECTION_ESTABLISHED
57 - AVDTP_SUBEVENT_SIGNALING_CONNECTION_RELEASED
58 - AVDTP_SUBEVENT_SIGNALING_SEP_FOUND
59 - AVDTP_SUBEVENT_SIGNALING_ACCEPT
60 - AVDTP_SUBEVENT_SIGNALING_REJECT
61 - AVDTP_SUBEVENT_SIGNALING_GENERAL_REJECT
62 - AVDTP_SUBEVENT_SIGNALING_MEDIA_CODEC_SBC_CAPABILITY
63 - AVDTP_SUBEVENT_SIGNALING_MEDIA_CODEC_OTHER_CAPABILITY
64 - AVDTP_SUBEVENT_SIGNALING_MEDIA_TRANSPORT_CAPABILITY
65 - AVDTP_SUBEVENT_SIGNALING_REPORTING_CAPABILITY
66 - AVDTP_SUBEVENT_SIGNALING_RECOVERY_CAPABILITY
67 - AVDTP_SUBEVENT_SIGNALING_CONTENT_PROTECTION_CAPABILITY
68 - AVDTP_SUBEVENT_SIGNALING_MULTIPLEXING_CAPABILITY
69 - AVDTP_SUBEVENT_SIGNALING_DELAY_REPORTING_CAPABILITY
70 - AVDTP_SUBEVENT_SIGNALING_HEADER_COMPRESSION_CAPABILITY
71 - AVDTP_SUBEVENT_SIGNALING_CAPABILITIES_DONE
72 - AVDTP_SUBEVENT_SIGNALING_SEP_DICOVERY_DONE
73 
74 Source:
75  - AVDTP_SUBEVENT_SIGNALING_DELAY_REPORT
76 
77 Sink or Source based on SEP Type:
78 - AVDTP_SUBEVENT_STREAMING_CONNECTION_ESTABLISHED
79 - AVDTP_SUBEVENT_STREAMING_CONNECTION_RELEASED
80 - AVDTP_SUBEVENT_STREAMING_CAN_SEND_MEDIA_PACKET_NOW
81 - AVDTP_SUBEVENT_SIGNALING_MEDIA_CODEC_SBC_CONFIGURATION
82 - AVDTP_SUBEVENT_SIGNALING_MEDIA_CODEC_OTHER_CONFIGURATION
83 
84 */
85 
86 static const char * avdtp_si_name[] = {
87     "ERROR",
88     "AVDTP_SI_DISCOVER",
89     "AVDTP_SI_GET_CAPABILITIES",
90     "AVDTP_SI_SET_CONFIGURATION",
91     "AVDTP_SI_GET_CONFIGURATION",
92     "AVDTP_SI_RECONFIGURE",
93     "AVDTP_SI_OPEN",
94     "AVDTP_SI_START",
95     "AVDTP_SI_CLOSE",
96     "AVDTP_SI_SUSPEND",
97     "AVDTP_SI_ABORT",
98     "AVDTP_SI_SECURITY_CONTROL",
99     "AVDTP_SI_GET_ALL_CAPABILITIES",
100     "AVDTP_SI_DELAY_REPORT"
101 };
102 const char * avdtp_si2str(uint16_t index){
103     if ((index <= 0) || (index >= sizeof(avdtp_si_name)/sizeof(avdtp_si_name[0]) )) return avdtp_si_name[0];
104     return avdtp_si_name[index];
105 }
106 
107 void avdtp_reset_stream_endpoint(avdtp_stream_endpoint_t * stream_endpoint){
108     stream_endpoint->media_con_handle = 0;
109     stream_endpoint->l2cap_media_cid = 0;
110     stream_endpoint->l2cap_reporting_cid = 0;
111     stream_endpoint->l2cap_recovery_cid = 0;
112 
113     stream_endpoint->state = AVDTP_STREAM_ENDPOINT_IDLE;
114     stream_endpoint->acceptor_config_state = AVDTP_ACCEPTOR_STREAM_CONFIG_IDLE;
115     stream_endpoint->initiator_config_state = AVDTP_INITIATOR_STREAM_CONFIG_IDLE;
116 
117     stream_endpoint->connection = NULL;
118 
119     stream_endpoint->sep.in_use = 0;
120     memset(&stream_endpoint->remote_sep, 0, sizeof(avdtp_sep_t));
121 
122     stream_endpoint->remote_capabilities_bitmap = 0;
123     memset(&stream_endpoint->remote_capabilities, 0, sizeof(avdtp_capabilities_t));
124     stream_endpoint->remote_configuration_bitmap = 0;
125     memset(&stream_endpoint->remote_configuration, 0, sizeof(avdtp_capabilities_t));
126 
127     // temporary SBC config used by A2DP Source
128     memset(stream_endpoint->media_codec_sbc_info, 0, 4);
129 
130     stream_endpoint->media_disconnect = 0;
131     stream_endpoint->media_connect = 0;
132     stream_endpoint->start_stream = 0;
133     stream_endpoint->close_stream = 0;
134     stream_endpoint->request_can_send_now = 0;
135     stream_endpoint->abort_stream = 0;
136     stream_endpoint->suspend_stream = 0;
137     stream_endpoint->sequence_number = 0;
138 }
139 
140 int get_bit16(uint16_t bitmap, int position){
141     return (bitmap >> position) & 1;
142 }
143 
144 uint16_t store_bit16(uint16_t bitmap, int position, uint8_t value){
145     if (value){
146         bitmap |= 1 << position;
147     } else {
148         bitmap &= ~ (1 << position);
149     }
150     return bitmap;
151 }
152 
153 avdtp_message_type_t avdtp_get_signaling_packet_type(uint8_t * packet){
154     return (avdtp_message_type_t) (packet[0] & 0x03);
155 }
156 
157 int avdtp_read_signaling_header(avdtp_signaling_packet_t * signaling_header, uint8_t * packet, uint16_t size){
158     int pos = 0;
159     if (size < 2) return pos;
160     signaling_header->transaction_label = packet[pos] >> 4;
161     signaling_header->packet_type = (avdtp_packet_type_t)((packet[pos] >> 2) & 0x03);
162     signaling_header->message_type = (avdtp_message_type_t) (packet[pos] & 0x03);
163     pos++;
164     memset(signaling_header->command, 0, sizeof(signaling_header->command));
165     switch (signaling_header->packet_type){
166         case AVDTP_SINGLE_PACKET:
167             signaling_header->num_packets = 0;
168             signaling_header->offset = 0;
169             signaling_header->size = 0;
170             break;
171         case AVDTP_END_PACKET:
172             signaling_header->num_packets = 0;
173             break;
174         case AVDTP_START_PACKET:
175             signaling_header->num_packets = packet[pos++];
176             signaling_header->size = 0;
177             signaling_header->offset = 0;
178             break;
179         case AVDTP_CONTINUE_PACKET:
180             if (signaling_header->num_packets <= 0) {
181                 log_info("    ERROR: wrong num fragmented packets\n");
182                 break;
183             }
184             signaling_header->num_packets--;
185             break;
186         default:
187             btstack_assert(false);
188             break;
189     }
190     signaling_header->signal_identifier = (avdtp_signal_identifier_t)(packet[pos++] & 0x3f);
191     return pos;
192 }
193 
194 static bool avdtp_is_basic_capability(int service_category){
195     return (AVDTP_MEDIA_TRANSPORT <= service_category) && (service_category <= AVDTP_MEDIA_CODEC);
196 }
197 
198 int avdtp_pack_service_capabilities(uint8_t *buffer, int size, avdtp_capabilities_t caps, avdtp_service_category_t category) {
199     UNUSED(size);
200 
201     int i;
202     // pos = 0 reserved for length
203     int pos = 1;
204     switch(category){
205         case AVDTP_MEDIA_TRANSPORT:
206         case AVDTP_REPORTING:
207         case AVDTP_DELAY_REPORTING:
208             break;
209         case AVDTP_RECOVERY:
210             buffer[pos++] = caps.recovery.recovery_type; // 0x01=RFC2733
211             buffer[pos++] = caps.recovery.maximum_recovery_window_size;
212             buffer[pos++] = caps.recovery.maximum_number_media_packets;
213             break;
214         case AVDTP_CONTENT_PROTECTION:
215             buffer[pos++] = caps.content_protection.cp_type_value_len + 2;
216             big_endian_store_16(buffer, pos, caps.content_protection.cp_type);
217             pos += 2;
218             (void)memcpy(buffer + pos, caps.content_protection.cp_type_value,
219                          caps.content_protection.cp_type_value_len);
220             pos += caps.content_protection.cp_type_value_len;
221             break;
222         case AVDTP_HEADER_COMPRESSION:
223             buffer[pos++] = (caps.header_compression.back_ch << 7) | (caps.header_compression.media << 6) | (caps.header_compression.recovery << 5);
224             break;
225         case AVDTP_MULTIPLEXING:
226             buffer[pos++] = caps.multiplexing_mode.fragmentation << 7;
227             for (i=0; i<caps.multiplexing_mode.transport_identifiers_num; i++){
228                 buffer[pos++] = caps.multiplexing_mode.transport_session_identifiers[i] << 7;
229                 buffer[pos++] = caps.multiplexing_mode.tcid[i] << 7;
230                 // media, reporting. recovery
231             }
232             break;
233         case AVDTP_MEDIA_CODEC:
234             buffer[pos++] = ((uint8_t)caps.media_codec.media_type) << 4;
235             buffer[pos++] = (uint8_t)caps.media_codec.media_codec_type;
236             for (i = 0; i<caps.media_codec.media_codec_information_len; i++){
237                 buffer[pos++] = caps.media_codec.media_codec_information[i];
238             }
239             break;
240         default:
241             break;
242     }
243     buffer[0] = pos - 1; // length
244     return pos;
245 }
246 
247 static int avdtp_unpack_service_capabilities_has_errors(avdtp_connection_t * connection, avdtp_signal_identifier_t signal_identifier, avdtp_service_category_t category, uint8_t cap_len){
248     connection->error_code = 0;
249 
250     if ((category == AVDTP_SERVICE_CATEGORY_INVALID_0) ||
251         ((category == AVDTP_SERVICE_CATEGORY_INVALID_FF) && (signal_identifier == AVDTP_SI_RECONFIGURE))){
252         log_info("    ERROR: BAD SERVICE CATEGORY %d\n", category);
253         connection->reject_service_category = category;
254         connection->error_code = BAD_SERV_CATEGORY;
255         return 1;
256     }
257 
258     if (signal_identifier == AVDTP_SI_RECONFIGURE){
259         if ( (category != AVDTP_CONTENT_PROTECTION) && (category != AVDTP_MEDIA_CODEC)){
260             log_info("    ERROR: REJECT CATEGORY, INVALID_CAPABILITIES\n");
261             connection->reject_service_category = category;
262             connection->error_code = INVALID_CAPABILITIES;
263             return 1;
264         }
265     }
266 
267     switch(category){
268         case AVDTP_MEDIA_TRANSPORT:
269             if (cap_len != 0){
270                 log_info("    ERROR: REJECT CATEGORY, BAD_MEDIA_TRANSPORT\n");
271                 connection->reject_service_category = category;
272                 connection->error_code = BAD_MEDIA_TRANSPORT_FORMAT;
273                 return 1;
274             }
275             break;
276         case AVDTP_REPORTING:
277         case AVDTP_DELAY_REPORTING:
278             if (cap_len != 0){
279                 log_info("    ERROR: REJECT CATEGORY, BAD_LENGTH\n");
280                 connection->reject_service_category = category;
281                 connection->error_code = BAD_LENGTH;
282                 return 1;
283             }
284             break;
285         case AVDTP_RECOVERY:
286             if (cap_len != 3){
287                 log_info("    ERROR: REJECT CATEGORY, BAD_MEDIA_TRANSPORT\n");
288                 connection->reject_service_category = category;
289                 connection->error_code = BAD_RECOVERY_FORMAT;
290                 return 1;
291             }
292             break;
293         case AVDTP_CONTENT_PROTECTION:
294             if (cap_len < 2){
295                 log_info("    ERROR: REJECT CATEGORY, BAD_CP_FORMAT\n");
296                 connection->reject_service_category = category;
297                 connection->error_code = BAD_CP_FORMAT;
298                 return 1;
299             }
300             break;
301         case AVDTP_HEADER_COMPRESSION:
302             // TODO: find error code for bad header compression
303             if (cap_len != 1){
304                 log_info("    ERROR: REJECT CATEGORY, BAD_HEADER_COMPRESSION\n");
305                 connection->reject_service_category = category;
306                 connection->error_code = BAD_RECOVERY_FORMAT;
307                 return 1;
308             }
309             break;
310         case AVDTP_MULTIPLEXING:
311             break;
312         case AVDTP_MEDIA_CODEC:
313             break;
314         default:
315             break;
316     }
317     return 0;
318 }
319 
320 uint16_t avdtp_unpack_service_capabilities(avdtp_connection_t * connection, avdtp_signal_identifier_t signal_identifier, avdtp_capabilities_t * caps, uint8_t * packet, uint16_t size){
321 
322     int i;
323 
324     uint16_t registered_service_categories = 0;
325     uint16_t to_process = size;
326 
327     while (to_process >= 2){
328 
329         avdtp_service_category_t category = (avdtp_service_category_t) packet[0];
330         uint8_t cap_len = packet[1];
331         packet     += 2;
332         to_process -= 2;
333 
334         if (cap_len > to_process){
335             connection->reject_service_category = category;
336             connection->error_code = BAD_LENGTH;
337             return 0;
338         }
339 
340         if (avdtp_unpack_service_capabilities_has_errors(connection, signal_identifier, category, cap_len)) return 0;
341 
342         int category_valid = 1;
343 
344         uint8_t * data = packet;
345         uint16_t  pos = 0;
346 
347         switch(category){
348             case AVDTP_RECOVERY:
349                 caps->recovery.recovery_type = data[pos++];
350                 caps->recovery.maximum_recovery_window_size = data[pos++];
351                 caps->recovery.maximum_number_media_packets = data[pos++];
352                 break;
353             case AVDTP_CONTENT_PROTECTION:
354                 caps->content_protection.cp_type = big_endian_read_16(data, 0);
355                 caps->content_protection.cp_type_value_len = cap_len - 2;
356                 // connection->reject_service_category = category;
357                 // connection->error_code = UNSUPPORTED_CONFIGURATION;
358                 // support for content protection goes here
359                 break;
360             case AVDTP_HEADER_COMPRESSION:
361                 caps->header_compression.back_ch  = (data[0] >> 7) & 1;
362                 caps->header_compression.media    = (data[0] >> 6) & 1;
363                 caps->header_compression.recovery = (data[0] >> 5) & 1;
364                 break;
365             case AVDTP_MULTIPLEXING:
366                 caps->multiplexing_mode.fragmentation = (data[pos++] >> 7) & 1;
367                 // read [tsid, tcid] for media, reporting. recovery respectively
368                 caps->multiplexing_mode.transport_identifiers_num = 3;
369                 for (i=0; i<caps->multiplexing_mode.transport_identifiers_num; i++){
370                     caps->multiplexing_mode.transport_session_identifiers[i] = (data[pos++] >> 7) & 1;
371                     caps->multiplexing_mode.tcid[i] = (data[pos++] >> 7) & 1;
372                 }
373                 break;
374             case AVDTP_MEDIA_CODEC:
375                 caps->media_codec.media_type = (avdtp_media_type_t)(data[pos++] >> 4);
376                 caps->media_codec.media_codec_type = (avdtp_media_codec_type_t)(data[pos++]);
377                 caps->media_codec.media_codec_information_len = cap_len - 2;
378                 caps->media_codec.media_codec_information = &data[pos++];
379                 break;
380             case AVDTP_MEDIA_TRANSPORT:
381             case AVDTP_REPORTING:
382             case AVDTP_DELAY_REPORTING:
383                 break;
384             default:
385                 category_valid = 0;
386                 break;
387         }
388 
389         if (category_valid) {
390             registered_service_categories = store_bit16(registered_service_categories, category, 1);
391         }
392 
393         packet     += cap_len;
394         to_process -= cap_len;
395     }
396 
397     return registered_service_categories;
398 }
399 
400 void avdtp_prepare_capabilities(avdtp_signaling_packet_t * signaling_packet, uint8_t transaction_label, uint16_t service_categories, avdtp_capabilities_t capabilities, uint8_t identifier){
401     if (signaling_packet->offset) return;
402     bool basic_capabilities_only = false;
403     signaling_packet->message_type = AVDTP_RESPONSE_ACCEPT_MSG;
404     int i;
405 
406     signaling_packet->size = 0;
407     memset(signaling_packet->command, 0 , sizeof(signaling_packet->command));
408 
409     switch (identifier) {
410         case AVDTP_SI_GET_CAPABILITIES:
411             basic_capabilities_only = true;
412             break;
413         case AVDTP_SI_GET_ALL_CAPABILITIES:
414             break;
415         case AVDTP_SI_SET_CONFIGURATION:
416             signaling_packet->command[signaling_packet->size++] = signaling_packet->acp_seid << 2;
417             signaling_packet->command[signaling_packet->size++] = signaling_packet->int_seid << 2;
418             signaling_packet->message_type = AVDTP_CMD_MSG;
419             break;
420         case AVDTP_SI_RECONFIGURE:
421             signaling_packet->command[signaling_packet->size++] = signaling_packet->acp_seid << 2;
422             signaling_packet->message_type = AVDTP_CMD_MSG;
423             break;
424         default:
425             log_error("avdtp_prepare_capabilities wrong identifier %d", identifier);
426             break;
427     }
428 
429     for (i = AVDTP_MEDIA_TRANSPORT; i <= AVDTP_DELAY_REPORTING; i++){
430         int registered_category = get_bit16(service_categories, i);
431         if (!registered_category && (identifier == AVDTP_SI_SET_CONFIGURATION)){
432             // TODO: introduce bitmap of mandatory categories
433             if (i == AVDTP_MEDIA_TRANSPORT){
434                 registered_category = true;
435             }
436         }
437         // AVDTP_SI_GET_CAPABILITIES reports only basic capabilities (i.e., it skips non-basic categories)
438         if (basic_capabilities_only && !avdtp_is_basic_capability(i)){
439             registered_category = false;
440         }
441 
442         if (registered_category){
443             // service category
444             signaling_packet->command[signaling_packet->size++] = i;
445             signaling_packet->size += avdtp_pack_service_capabilities(signaling_packet->command + signaling_packet->size,
446                     sizeof(signaling_packet->command) - signaling_packet->size, capabilities, (avdtp_service_category_t) i);
447         }
448     }
449     signaling_packet->signal_identifier = (avdtp_signal_identifier_t)identifier;
450     signaling_packet->transaction_label = transaction_label;
451 }
452 
453 int avdtp_signaling_create_fragment(uint16_t cid, avdtp_signaling_packet_t * signaling_packet, uint8_t * out_buffer) {
454     int mtu = l2cap_get_remote_mtu_for_local_cid(cid);
455     int data_len = 0;
456 
457     uint16_t offset = signaling_packet->offset;
458     uint16_t pos = 1;
459 
460     if (offset == 0){
461         if (signaling_packet->size <= (mtu - 2)){
462             signaling_packet->packet_type = AVDTP_SINGLE_PACKET;
463             out_buffer[pos++] = signaling_packet->signal_identifier;
464             data_len = signaling_packet->size;
465         } else {
466             signaling_packet->packet_type = AVDTP_START_PACKET;
467             out_buffer[pos++] = (mtu + signaling_packet->size)/ (mtu-1);
468             out_buffer[pos++] = signaling_packet->signal_identifier;
469             data_len = mtu - 3;
470             signaling_packet->offset = data_len;
471         }
472     } else {
473         int remaining_bytes = signaling_packet->size - offset;
474         if (remaining_bytes <= (mtu - 1)){
475             signaling_packet->packet_type = AVDTP_END_PACKET;
476             data_len = remaining_bytes;
477             signaling_packet->offset = 0;
478         } else{
479             signaling_packet->packet_type = AVDTP_CONTINUE_PACKET;
480             data_len = mtu - 1;
481             signaling_packet->offset += data_len;
482         }
483     }
484     out_buffer[0] = avdtp_header(signaling_packet->transaction_label, signaling_packet->packet_type, signaling_packet->message_type);
485     (void)memcpy(out_buffer + pos, signaling_packet->command + offset,
486                  data_len);
487     pos += data_len;
488     return pos;
489 }
490 
491 
492 void avdtp_signaling_emit_connection_established(uint16_t avdtp_cid, bd_addr_t addr, hci_con_handle_t con_handle, uint8_t status) {
493     uint8_t event[14];
494     int pos = 0;
495     event[pos++] = HCI_EVENT_AVDTP_META;
496     event[pos++] = sizeof(event) - 2;
497     event[pos++] = AVDTP_SUBEVENT_SIGNALING_CONNECTION_ESTABLISHED;
498     little_endian_store_16(event, pos, avdtp_cid);
499     pos += 2;
500     reverse_bd_addr(addr,&event[pos]);
501     pos += 6;
502     little_endian_store_16(event, pos, con_handle);
503     pos += 2;
504     event[pos++] = status;
505     avdtp_emit_sink_and_source(event, pos);
506 }
507 
508 void avdtp_signaling_emit_connection_released(uint16_t avdtp_cid) {
509     uint8_t event[5];
510     int pos = 0;
511     event[pos++] = HCI_EVENT_AVDTP_META;
512     event[pos++] = sizeof(event) - 2;
513     event[pos++] = AVDTP_SUBEVENT_SIGNALING_CONNECTION_RELEASED;
514     little_endian_store_16(event, pos, avdtp_cid);
515     pos += 2;
516     avdtp_emit_sink_and_source(event, pos);
517 }
518 
519 void avdtp_signaling_emit_sep(uint16_t avdtp_cid, avdtp_sep_t sep) {
520     uint8_t event[9];
521     int pos = 0;
522     event[pos++] = HCI_EVENT_AVDTP_META;
523     event[pos++] = sizeof(event) - 2;
524     event[pos++] = AVDTP_SUBEVENT_SIGNALING_SEP_FOUND;
525     little_endian_store_16(event, pos, avdtp_cid);
526     pos += 2;
527     event[pos++] = sep.seid;
528     event[pos++] = sep.in_use;
529     event[pos++] = sep.media_type;
530     event[pos++] = sep.type;
531     avdtp_emit_sink_and_source(event, pos);
532 }
533 
534 void avdtp_signaling_emit_sep_done(uint16_t avdtp_cid) {
535     uint8_t event[5];
536     int pos = 0;
537     event[pos++] = HCI_EVENT_AVDTP_META;
538     event[pos++] = sizeof(event) - 2;
539     event[pos++] = AVDTP_SUBEVENT_SIGNALING_SEP_DICOVERY_DONE;
540     little_endian_store_16(event, pos, avdtp_cid);
541     pos += 2;
542     avdtp_emit_sink_and_source(event, pos);
543 }
544 
545 void avdtp_signaling_emit_accept(uint16_t avdtp_cid, uint8_t local_seid, avdtp_signal_identifier_t identifier, bool is_initiator) {
546     uint8_t event[8];
547     int pos = 0;
548     event[pos++] = HCI_EVENT_AVDTP_META;
549     event[pos++] = sizeof(event) - 2;
550     event[pos++] = AVDTP_SUBEVENT_SIGNALING_ACCEPT;
551     little_endian_store_16(event, pos, avdtp_cid);
552     pos += 2;
553     event[pos++] = local_seid;
554     event[pos++] = is_initiator ? 1 : 0;
555     event[pos++] = identifier;
556     avdtp_emit_sink_and_source(event, pos);
557 }
558 
559 void avdtp_signaling_emit_accept_for_stream_endpoint(avdtp_stream_endpoint_t * stream_endpoint, uint8_t local_seid,  avdtp_signal_identifier_t identifier, bool is_initiator){
560     uint8_t event[8];
561     int pos = 0;
562     event[pos++] = HCI_EVENT_AVDTP_META;
563     event[pos++] = sizeof(event) - 2;
564     event[pos++] = AVDTP_SUBEVENT_SIGNALING_ACCEPT;
565     little_endian_store_16(event, pos, stream_endpoint->connection->avdtp_cid);
566     pos += 2;
567     event[pos++] = local_seid;
568     event[pos++] = is_initiator ? 1 : 0;
569     event[pos++] = identifier;
570 
571     btstack_packet_handler_t packet_handler = avdtp_packet_handler_for_stream_endpoint(stream_endpoint);
572     (*packet_handler)(HCI_EVENT_PACKET, 0, event, pos);
573 }
574 
575 void avdtp_signaling_emit_reject(uint16_t avdtp_cid, uint8_t local_seid, avdtp_signal_identifier_t identifier, bool is_initiator) {
576     uint8_t event[8];
577     int pos = 0;
578     event[pos++] = HCI_EVENT_AVDTP_META;
579     event[pos++] = sizeof(event) - 2;
580     event[pos++] = AVDTP_SUBEVENT_SIGNALING_REJECT;
581     little_endian_store_16(event, pos, avdtp_cid);
582     pos += 2;
583     event[pos++] = local_seid;
584     event[pos++] = is_initiator ? 1 : 0;
585     event[pos++] = identifier;
586     avdtp_emit_sink_and_source(event, pos);
587 }
588 
589 void avdtp_signaling_emit_general_reject(uint16_t avdtp_cid, uint8_t local_seid, avdtp_signal_identifier_t identifier, bool is_initiator) {
590     uint8_t event[8];
591     int pos = 0;
592     event[pos++] = HCI_EVENT_AVDTP_META;
593     event[pos++] = sizeof(event) - 2;
594     event[pos++] = AVDTP_SUBEVENT_SIGNALING_GENERAL_REJECT;
595     little_endian_store_16(event, pos, avdtp_cid);
596     pos += 2;
597     event[pos++] = local_seid;
598     event[pos++] = is_initiator ? 1 : 0;
599     event[pos++] = identifier;
600     avdtp_emit_sink_and_source(event, pos);
601 }
602 
603 static inline void
604 avdtp_signaling_emit_capability(uint8_t capability_subevent_id, uint16_t avdtp_cid, uint8_t remote_seid) {
605     uint8_t event[6];
606     int pos = 0;
607     event[pos++] = HCI_EVENT_AVDTP_META;
608     event[pos++] = sizeof(event) - 2;
609     event[pos++] = capability_subevent_id;
610     little_endian_store_16(event, pos, avdtp_cid);
611     pos += 2;
612     event[pos++] = remote_seid;
613     avdtp_emit_sink_and_source(event, pos);
614 }
615 
616 static void avdtp_signaling_emit_media_codec_sbc_capability(uint16_t avdtp_cid, uint8_t remote_seid, adtvp_media_codec_capabilities_t media_codec) {
617     uint8_t event[14];
618     int pos = 0;
619     event[pos++] = HCI_EVENT_AVDTP_META;
620     event[pos++] = sizeof(event) - 2;
621     event[pos++] = AVDTP_SUBEVENT_SIGNALING_MEDIA_CODEC_SBC_CAPABILITY;
622     little_endian_store_16(event, pos, avdtp_cid);
623     pos += 2;
624     event[pos++] = remote_seid;
625     event[pos++] = media_codec.media_type;
626     event[pos++] = media_codec.media_codec_information[0] >> 4;
627     event[pos++] = media_codec.media_codec_information[0] & 0x0F;
628     event[pos++] = media_codec.media_codec_information[1] >> 4;
629     event[pos++] = (media_codec.media_codec_information[1] & 0x0F) >> 2;
630     event[pos++] = media_codec.media_codec_information[1] & 0x03;
631     event[pos++] = media_codec.media_codec_information[2];
632     event[pos++] = media_codec.media_codec_information[3];
633     avdtp_emit_sink_and_source(event, pos);
634 }
635 
636 static void avdtp_signaling_emit_media_codec_other_capability(uint16_t avdtp_cid, uint8_t remote_seid, adtvp_media_codec_capabilities_t media_codec) {
637     uint8_t event[MAX_MEDIA_CODEC_INFORMATION_LENGTH + 11];
638     int pos = 0;
639     event[pos++] = HCI_EVENT_AVDTP_META;
640     event[pos++] = sizeof(event) - 2;
641     event[pos++] = AVDTP_SUBEVENT_SIGNALING_MEDIA_CODEC_OTHER_CAPABILITY;
642     little_endian_store_16(event, pos, avdtp_cid);
643     pos += 2;
644     event[pos++] = remote_seid;
645     event[pos++] = media_codec.media_type;
646     little_endian_store_16(event, pos, media_codec.media_codec_type);
647     pos += 2;
648     little_endian_store_16(event, pos, media_codec.media_codec_information_len);
649     pos += 2;
650     (void)memcpy(event + pos, media_codec.media_codec_information,
651                  btstack_min(media_codec.media_codec_information_len, MAX_MEDIA_CODEC_INFORMATION_LENGTH));
652     avdtp_emit_sink_and_source(event, pos);
653 }
654 
655 static void
656 avdtp_signaling_emit_media_transport_capability(uint16_t avdtp_cid, uint8_t remote_seid) {
657 	avdtp_signaling_emit_capability(AVDTP_SUBEVENT_SIGNALING_MEDIA_TRANSPORT_CAPABILITY, avdtp_cid,
658 									remote_seid);
659 }
660 
661 static void avdtp_signaling_emit_reporting_capability(uint16_t avdtp_cid, uint8_t remote_seid) {
662 	avdtp_signaling_emit_capability(AVDTP_SUBEVENT_SIGNALING_REPORTING_CAPABILITY, avdtp_cid, remote_seid);
663 }
664 
665 static void
666 avdtp_signaling_emit_delay_reporting_capability(uint16_t avdtp_cid, uint8_t remote_seid) {
667 	avdtp_signaling_emit_capability(AVDTP_SUBEVENT_SIGNALING_DELAY_REPORTING_CAPABILITY, avdtp_cid,
668 									remote_seid);
669 }
670 
671 static void avdtp_signaling_emit_recovery_capability(uint16_t avdtp_cid, uint8_t remote_seid, avdtp_recovery_capabilities_t *recovery) {
672     uint8_t event[9];
673     int pos = 0;
674     event[pos++] = HCI_EVENT_AVDTP_META;
675     event[pos++] = sizeof(event) - 2;
676     event[pos++] = AVDTP_SUBEVENT_SIGNALING_RECOVERY_CAPABILITY;
677     little_endian_store_16(event, pos, avdtp_cid);
678     pos += 2;
679     event[pos++] = remote_seid;
680     event[pos++] = recovery->recovery_type;
681     event[pos++] = recovery->maximum_recovery_window_size;
682     event[pos++] = recovery->maximum_number_media_packets;
683     avdtp_emit_sink_and_source(event, pos);
684 }
685 
686 static void
687 avdtp_signaling_emit_content_protection_capability(uint16_t avdtp_cid, uint8_t remote_seid, adtvp_content_protection_t *content_protection) {
688     uint8_t event[21];
689     int pos = 0;
690     event[pos++] = HCI_EVENT_AVDTP_META;
691     event[pos++] = sizeof(event) - 2;
692     event[pos++] = AVDTP_SUBEVENT_SIGNALING_CONTENT_PROTECTION_CAPABILITY;
693     little_endian_store_16(event, pos, avdtp_cid);
694     pos += 2;
695     event[pos++] = remote_seid;
696 
697     little_endian_store_16(event, pos, content_protection->cp_type);
698     pos += 2;
699     little_endian_store_16(event, pos, content_protection->cp_type_value_len);
700     pos += 2;
701 
702     //TODO: reserve place for value
703     if (content_protection->cp_type_value_len < 10){
704         (void)memcpy(event + pos, content_protection->cp_type_value,
705                      content_protection->cp_type_value_len);
706     }
707     avdtp_emit_sink_and_source(event, pos);
708 }
709 
710 
711 static void
712 avdtp_signaling_emit_header_compression_capability(uint16_t avdtp_cid, uint8_t remote_seid, avdtp_header_compression_capabilities_t *header_compression) {
713     uint8_t event[9];
714     int pos = 0;
715     event[pos++] = HCI_EVENT_AVDTP_META;
716     event[pos++] = sizeof(event) - 2;
717     event[pos++] = AVDTP_SUBEVENT_SIGNALING_HEADER_COMPRESSION_CAPABILITY;
718     little_endian_store_16(event, pos, avdtp_cid);
719     pos += 2;
720     event[pos++] = remote_seid;
721     event[pos++] = header_compression->back_ch;
722     event[pos++] = header_compression->media;
723     event[pos++] = header_compression->recovery;
724     avdtp_emit_sink_and_source(event, pos);
725 }
726 
727 static void
728 avdtp_signaling_emit_content_multiplexing_capability(uint16_t avdtp_cid, uint8_t remote_seid, avdtp_multiplexing_mode_capabilities_t *multiplexing_mode) {
729     uint8_t event[14];
730     int pos = 0;
731     event[pos++] = HCI_EVENT_AVDTP_META;
732     event[pos++] = sizeof(event) - 2;
733     event[pos++] = AVDTP_SUBEVENT_SIGNALING_MULTIPLEXING_CAPABILITY;
734     little_endian_store_16(event, pos, avdtp_cid);
735     pos += 2;
736     event[pos++] = remote_seid;
737 
738     event[pos++] = multiplexing_mode->fragmentation;
739     event[pos++] = multiplexing_mode->transport_identifiers_num;
740 
741     int i;
742     for (i = 0; i < 3; i++){
743         event[pos++] = multiplexing_mode->transport_session_identifiers[i];
744     }
745     for (i = 0; i < 3; i++){
746         event[pos++] = multiplexing_mode->tcid[i];
747     }
748     avdtp_emit_sink_and_source(event, pos);
749 }
750 
751 static void avdtp_signaling_emit_capability_done(uint16_t avdtp_cid, uint8_t remote_seid) {
752     uint8_t event[6];
753     int pos = 0;
754     event[pos++] = HCI_EVENT_AVDTP_META;
755     event[pos++] = sizeof(event) - 2;
756     event[pos++] = AVDTP_SUBEVENT_SIGNALING_CAPABILITIES_DONE;
757     little_endian_store_16(event, pos, avdtp_cid);
758     pos += 2;
759     event[pos++] = remote_seid;
760     avdtp_emit_sink_and_source(event, pos);
761 }
762 
763 // emit events for all capabilities incl. final done event
764 void avdtp_signaling_emit_capabilities(uint16_t avdtp_cid, uint8_t remote_seid, avdtp_capabilities_t *capabilities,
765 									   uint16_t registered_service_categories) {
766     if (get_bit16(registered_service_categories, AVDTP_MEDIA_CODEC)){
767         switch (capabilities->media_codec.media_codec_type){
768             case AVDTP_CODEC_SBC:
769 				avdtp_signaling_emit_media_codec_sbc_capability(avdtp_cid, remote_seid, capabilities->media_codec);
770                 break;
771             default:
772 				avdtp_signaling_emit_media_codec_other_capability(avdtp_cid, remote_seid, capabilities->media_codec);
773                 break;
774         }
775     }
776 
777     if (get_bit16(registered_service_categories, AVDTP_MEDIA_TRANSPORT)){
778 		avdtp_signaling_emit_media_transport_capability(avdtp_cid, remote_seid);
779     }
780     if (get_bit16(registered_service_categories, AVDTP_REPORTING)){
781 		avdtp_signaling_emit_reporting_capability(avdtp_cid, remote_seid);
782     }
783     if (get_bit16(registered_service_categories, AVDTP_RECOVERY)){
784 		avdtp_signaling_emit_recovery_capability(avdtp_cid, remote_seid, &capabilities->recovery);
785     }
786     if (get_bit16(registered_service_categories, AVDTP_CONTENT_PROTECTION)){
787 		avdtp_signaling_emit_content_protection_capability(avdtp_cid, remote_seid,
788 														   &capabilities->content_protection);
789     }
790     if (get_bit16(registered_service_categories, AVDTP_HEADER_COMPRESSION)){
791 		avdtp_signaling_emit_header_compression_capability(avdtp_cid, remote_seid,
792 														   &capabilities->header_compression);
793     }
794     if (get_bit16(registered_service_categories, AVDTP_MULTIPLEXING)){
795 		avdtp_signaling_emit_content_multiplexing_capability(avdtp_cid, remote_seid,
796 															 &capabilities->multiplexing_mode);
797     }
798     if (get_bit16(registered_service_categories, AVDTP_DELAY_REPORTING)){
799 		avdtp_signaling_emit_delay_reporting_capability(avdtp_cid, remote_seid);
800     }
801 	avdtp_signaling_emit_capability_done(avdtp_cid, remote_seid);
802 }
803 
804 static void avdtp_signaling_emit_media_codec_sbc(avdtp_stream_endpoint_t *stream_endpoint, uint16_t avdtp_cid,
805                                      avdtp_media_type_t media_type, const uint8_t *media_codec_information,
806                                      uint8_t reconfigure) {
807 
808     btstack_packet_handler_t packet_handler = avdtp_packet_handler_for_stream_endpoint(stream_endpoint);
809     uint8_t local_seid = avdtp_local_seid(stream_endpoint);
810     uint8_t remote_seid = avdtp_remote_seid(stream_endpoint);
811 
812     uint8_t event[16 + 2];
813     int pos = 0;
814     event[pos++] = HCI_EVENT_AVDTP_META;
815     event[pos++] = sizeof(event) - 2;
816 
817     event[pos++] = AVDTP_SUBEVENT_SIGNALING_MEDIA_CODEC_SBC_CONFIGURATION;
818     little_endian_store_16(event, pos, avdtp_cid);
819     pos += 2;
820     event[pos++] = local_seid;
821     event[pos++] = remote_seid;
822     event[pos++] = reconfigure;
823 
824 
825     uint8_t sampling_frequency_bitmap = media_codec_information[0] >> 4;
826     uint8_t channel_mode_bitmap = media_codec_information[0] & 0x0F;
827     uint8_t block_length_bitmap = media_codec_information[1] >> 4;
828     uint8_t subbands_bitmap = (media_codec_information[1] & 0x0F) >> 2;
829 
830     uint8_t num_channels = 0;
831     if ((channel_mode_bitmap & AVDTP_SBC_JOINT_STEREO) ||
832         (channel_mode_bitmap & AVDTP_SBC_STEREO) ||
833         (channel_mode_bitmap & AVDTP_SBC_DUAL_CHANNEL)) {
834         num_channels = 2;
835     } else if (channel_mode_bitmap & AVDTP_SBC_MONO) {
836         num_channels = 1;
837     }
838 
839     uint16_t sampling_frequency = 0;
840     if (sampling_frequency_bitmap & AVDTP_SBC_48000) {
841         sampling_frequency = 48000;
842     } else if (sampling_frequency_bitmap & AVDTP_SBC_44100) {
843         sampling_frequency = 44100;
844     } else if (sampling_frequency_bitmap & AVDTP_SBC_32000) {
845         sampling_frequency = 32000;
846     } else if (sampling_frequency_bitmap & AVDTP_SBC_16000) {
847         sampling_frequency = 16000;
848     }
849 
850     uint8_t subbands = 0;
851     if (subbands_bitmap & AVDTP_SBC_SUBBANDS_8){
852         subbands = 8;
853     } else if (subbands_bitmap & AVDTP_SBC_SUBBANDS_4){
854         subbands = 4;
855     }
856 
857     uint8_t block_length = 0;
858     if (block_length_bitmap & AVDTP_SBC_BLOCK_LENGTH_16){
859         block_length = 16;
860     } else if (block_length_bitmap & AVDTP_SBC_BLOCK_LENGTH_12){
861         block_length = 12;
862     } else if (block_length_bitmap & AVDTP_SBC_BLOCK_LENGTH_8){
863         block_length = 8;
864     } else if (block_length_bitmap & AVDTP_SBC_BLOCK_LENGTH_4){
865         block_length = 4;
866     }
867 
868     event[pos++] = media_type;
869     little_endian_store_16(event, pos, sampling_frequency);
870     pos += 2;
871 
872     event[pos++] = channel_mode_bitmap;
873     event[pos++] = num_channels;
874     event[pos++] = block_length;
875     event[pos++] = subbands;
876     event[pos++] = media_codec_information[1] & 0x03;
877     event[pos++] = media_codec_information[2];
878     event[pos++] = media_codec_information[3];
879     (*packet_handler)(HCI_EVENT_PACKET, 0, event, sizeof(event));
880 }
881 
882 static void avdtp_signaling_emit_media_codec_other(avdtp_stream_endpoint_t *stream_endpoint, uint16_t avdtp_cid,
883                                        adtvp_media_codec_capabilities_t * media_codec, uint8_t reconfigure) {
884 
885     btstack_packet_handler_t packet_handler = avdtp_packet_handler_for_stream_endpoint(stream_endpoint);
886     uint8_t local_seid = avdtp_local_seid(stream_endpoint);
887     uint8_t remote_seid = avdtp_remote_seid(stream_endpoint);
888 
889     uint8_t event[MAX_MEDIA_CODEC_INFORMATION_LENGTH + 13];
890     int pos = 0;
891     event[pos++] = HCI_EVENT_AVDTP_META;
892     event[pos++] = sizeof(event) - 2;
893     event[pos++] = AVDTP_SUBEVENT_SIGNALING_MEDIA_CODEC_OTHER_CONFIGURATION;
894     little_endian_store_16(event, pos, avdtp_cid);
895     pos += 2;
896     event[pos++] = local_seid;
897     event[pos++] = remote_seid;
898     event[pos++] = reconfigure;
899     event[pos++] = media_codec->media_type;
900     little_endian_store_16(event, pos, media_codec->media_codec_type);
901     pos += 2;
902     little_endian_store_16(event, pos, media_codec->media_codec_information_len);
903     pos += 2;
904 
905     int media_codec_len = btstack_min(MAX_MEDIA_CODEC_INFORMATION_LENGTH, media_codec->media_codec_information_len);
906     (void)memcpy(event + pos, media_codec->media_codec_information, media_codec_len);
907 
908     (*packet_handler)(HCI_EVENT_PACKET, 0, event, sizeof(event));
909 }
910 
911 void avdtp_signaling_emit_delay(uint16_t avdtp_cid, uint8_t local_seid, uint16_t delay) {
912     uint8_t event[8];
913     int pos = 0;
914     event[pos++] = HCI_EVENT_AVDTP_META;
915     event[pos++] = sizeof(event) - 2;
916     event[pos++] = AVDTP_SUBEVENT_SIGNALING_DELAY_REPORT;
917     little_endian_store_16(event, pos, avdtp_cid);
918     pos += 2;
919     event[pos++] = local_seid;
920     little_endian_store_16(event, pos, delay);
921     pos += 2;
922     avdtp_emit_source(event, sizeof(event));
923 }
924 
925 void avdtp_signaling_emit_media_codec_sbc_configuration(avdtp_stream_endpoint_t *stream_endpoint, uint16_t avdtp_cid,
926                                                         avdtp_media_type_t media_type,
927                                                         const uint8_t *media_codec_information) {
928     avdtp_signaling_emit_media_codec_sbc(stream_endpoint, avdtp_cid, media_type,
929                                          media_codec_information, 0);
930 }
931 
932 void avdtp_signaling_emit_media_codec_other_configuration(avdtp_stream_endpoint_t *stream_endpoint, uint16_t avdtp_cid,
933                                                           adtvp_media_codec_capabilities_t * media_codec) {
934     avdtp_signaling_emit_media_codec_other(stream_endpoint, avdtp_cid, media_codec, 0);
935 }
936 
937 void avdtp_signaling_emit_configuration(avdtp_stream_endpoint_t *stream_endpoint, uint16_t avdtp_cid,
938                                         avdtp_capabilities_t *configuration, uint16_t configured_service_categories) {
939 
940     if (get_bit16(configured_service_categories, AVDTP_MEDIA_CODEC)){
941         switch (configuration->media_codec.media_codec_type){
942             case AVDTP_CODEC_SBC:
943                 avdtp_signaling_emit_media_codec_sbc_configuration(
944                         stream_endpoint, avdtp_cid,
945                         configuration->media_codec.media_type,
946                         configuration->media_codec.media_codec_information);
947                 break;
948             default:
949                 avdtp_signaling_emit_media_codec_other_configuration(stream_endpoint, avdtp_cid,
950                                                                      &configuration->media_codec);
951                 break;
952         }
953     }
954 }
955 
956 void avdtp_streaming_emit_connection_established(avdtp_stream_endpoint_t *stream_endpoint, uint8_t status) {
957     uint8_t event[14];
958     int pos = 0;
959     event[pos++] = HCI_EVENT_AVDTP_META;
960     event[pos++] = sizeof(event) - 2;
961     event[pos++] = AVDTP_SUBEVENT_STREAMING_CONNECTION_ESTABLISHED;
962     little_endian_store_16(event, pos, stream_endpoint->connection->avdtp_cid);
963     pos += 2;
964     reverse_bd_addr(stream_endpoint->connection->remote_addr, &event[pos]);
965     pos += 6;
966     event[pos++] = avdtp_local_seid(stream_endpoint);
967     event[pos++] = avdtp_remote_seid(stream_endpoint);
968     event[pos++] = status;
969 
970     btstack_packet_handler_t packet_handler = avdtp_packet_handler_for_stream_endpoint(stream_endpoint);
971     (*packet_handler)(HCI_EVENT_PACKET, 0, event, sizeof(event));
972 }
973 
974 void avdtp_streaming_emit_connection_released(avdtp_stream_endpoint_t *stream_endpoint, uint16_t avdtp_cid, uint8_t local_seid) {
975     uint8_t event[6];
976     int pos = 0;
977     event[pos++] = HCI_EVENT_AVDTP_META;
978     event[pos++] = sizeof(event) - 2;
979     event[pos++] = AVDTP_SUBEVENT_STREAMING_CONNECTION_RELEASED;
980     little_endian_store_16(event, pos, avdtp_cid);
981     pos += 2;
982     event[pos++] = local_seid;
983 
984     btstack_packet_handler_t packet_handler = avdtp_packet_handler_for_stream_endpoint(stream_endpoint);
985     (*packet_handler)(HCI_EVENT_PACKET, 0, event, sizeof(event));
986 }
987 
988 void avdtp_streaming_emit_can_send_media_packet_now(avdtp_stream_endpoint_t *stream_endpoint, uint16_t sequence_number) {
989     uint8_t event[8];
990     int pos = 0;
991     event[pos++] = HCI_EVENT_AVDTP_META;
992     event[pos++] = sizeof(event) - 2;
993     event[pos++] = AVDTP_SUBEVENT_STREAMING_CAN_SEND_MEDIA_PACKET_NOW;
994     little_endian_store_16(event, pos, stream_endpoint->connection->avdtp_cid);
995     pos += 2;
996     event[pos++] = avdtp_local_seid(stream_endpoint);
997     little_endian_store_16(event, pos, sequence_number);
998     pos += 2;
999 
1000     btstack_packet_handler_t packet_handler = avdtp_packet_handler_for_stream_endpoint(stream_endpoint);
1001     (*packet_handler)(HCI_EVENT_PACKET, 0, event, sizeof(event));
1002 }
1003 
1004 uint8_t avdtp_request_can_send_now_acceptor(avdtp_connection_t *connection) {
1005     if (!connection) return ERROR_CODE_UNKNOWN_CONNECTION_IDENTIFIER;
1006     connection->wait_to_send_acceptor = true;
1007     l2cap_request_can_send_now_event(connection->l2cap_signaling_cid);
1008     return ERROR_CODE_SUCCESS;
1009 }
1010 
1011 uint8_t avdtp_request_can_send_now_initiator(avdtp_connection_t *connection) {
1012     if (!connection) return ERROR_CODE_UNKNOWN_CONNECTION_IDENTIFIER;
1013     connection->wait_to_send_initiator = true;
1014     l2cap_request_can_send_now_event(connection->l2cap_signaling_cid);
1015     return ERROR_CODE_SUCCESS;
1016 }
1017 
1018 uint8_t avdtp_local_seid(avdtp_stream_endpoint_t * stream_endpoint){
1019     if (!stream_endpoint) return 0;
1020     return stream_endpoint->sep.seid;
1021 
1022 }
1023 
1024 uint8_t avdtp_remote_seid(avdtp_stream_endpoint_t * stream_endpoint){
1025     if (!stream_endpoint) return AVDTP_INVALID_SEP_SEID;
1026     return stream_endpoint->remote_sep.seid;
1027 }
1028 
1029 // helper for A2DP
1030 
1031 void a2dp_replace_subevent_id_and_emit_cmd(btstack_packet_handler_t callback, uint8_t * packet, uint16_t size, uint8_t subevent_id){
1032     UNUSED(size);
1033     btstack_assert(callback != NULL);
1034     // cache orig event and subevent id
1035     uint8_t orig_event_id    = packet[0];
1036     uint8_t orig_subevent_id = packet[2];
1037     // execute callback
1038     packet[0] = HCI_EVENT_A2DP_META;
1039     packet[2] = subevent_id;
1040     (*callback)(HCI_EVENT_PACKET, 0, packet, size);
1041     // restore id
1042     packet[0] = orig_event_id;
1043     packet[2] = orig_subevent_id;
1044 }
1045 
1046 void a2dp_emit_stream_event(btstack_packet_handler_t callback, uint16_t cid, uint8_t local_seid, uint8_t subevent_id){
1047     uint8_t event[6];
1048     int pos = 0;
1049     event[pos++] = HCI_EVENT_A2DP_META;
1050     event[pos++] = sizeof(event) - 2;
1051     event[pos++] = subevent_id;
1052     little_endian_store_16(event, pos, cid);
1053     pos += 2;
1054     event[pos++] = local_seid;
1055     (*callback)(HCI_EVENT_PACKET, 0, event, sizeof(event));
1056 }
1057