xref: /btstack/src/classic/avdtp_util.c (revision 74b2411b799883dc5ca85872669d49b38ec309ff)
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->connection = NULL;
114     stream_endpoint->state = AVDTP_STREAM_ENDPOINT_IDLE;
115     stream_endpoint->acceptor_config_state = AVDTP_ACCEPTOR_STREAM_CONFIG_IDLE;
116     stream_endpoint->initiator_config_state = AVDTP_INITIATOR_STREAM_CONFIG_IDLE;
117 
118     stream_endpoint->sep.in_use = 0;
119     memset(&stream_endpoint->remote_sep, 0, sizeof(avdtp_sep_t));
120     // memset(&stream_endpoint->remote_capabilities, 0, sizeof(avdtp_capabilities_t));
121     // memset(&stream_endpoint->remote_configuration, 0, sizeof(avdtp_capabilities_t));
122 
123     stream_endpoint->remote_capabilities_bitmap = 0;
124     stream_endpoint->remote_configuration_bitmap = 0;
125 
126     stream_endpoint->media_disconnect = 0;
127     stream_endpoint->media_connect = 0;
128     stream_endpoint->start_stream = 0;
129     stream_endpoint->stop_stream = 0;
130     stream_endpoint->send_stream = 0;
131     stream_endpoint->abort_stream = 0;
132     stream_endpoint->suspend_stream = 0;
133     stream_endpoint->sequence_number = 0;
134 }
135 
136 int get_bit16(uint16_t bitmap, int position){
137     return (bitmap >> position) & 1;
138 }
139 
140 uint16_t store_bit16(uint16_t bitmap, int position, uint8_t value){
141     if (value){
142         bitmap |= 1 << position;
143     } else {
144         bitmap &= ~ (1 << position);
145     }
146     return bitmap;
147 }
148 
149 avdtp_message_type_t avdtp_get_signaling_packet_type(uint8_t * packet){
150     return (avdtp_message_type_t) (packet[0] & 0x03);
151 }
152 
153 int avdtp_read_signaling_header(avdtp_signaling_packet_t * signaling_header, uint8_t * packet, uint16_t size){
154     int pos = 0;
155     if (size < 2) return pos;
156     signaling_header->transaction_label = packet[pos] >> 4;
157     signaling_header->packet_type = (avdtp_packet_type_t)((packet[pos] >> 2) & 0x03);
158     signaling_header->message_type = (avdtp_message_type_t) (packet[pos] & 0x03);
159     pos++;
160     memset(signaling_header->command, 0, sizeof(signaling_header->command));
161     switch (signaling_header->packet_type){
162         case AVDTP_SINGLE_PACKET:
163             signaling_header->num_packets = 0;
164             signaling_header->offset = 0;
165             signaling_header->size = 0;
166             break;
167         case AVDTP_END_PACKET:
168             signaling_header->num_packets = 0;
169             break;
170         case AVDTP_START_PACKET:
171             signaling_header->num_packets = packet[pos++];
172             signaling_header->size = 0;
173             signaling_header->offset = 0;
174             break;
175         case AVDTP_CONTINUE_PACKET:
176             if (signaling_header->num_packets <= 0) {
177                 log_info("    ERROR: wrong num fragmented packets\n");
178                 break;
179             }
180             signaling_header->num_packets--;
181             break;
182     }
183     signaling_header->signal_identifier = (avdtp_signal_identifier_t)(packet[pos++] & 0x3f);
184     return pos;
185 }
186 
187 static bool avdtp_is_basic_capability(int service_category){
188     return (AVDTP_MEDIA_TRANSPORT <= service_category) && (service_category <= AVDTP_MEDIA_CODEC);
189 }
190 
191 int avdtp_pack_service_capabilities(uint8_t *buffer, int size, avdtp_capabilities_t caps, avdtp_service_category_t category) {
192     UNUSED(size);
193 
194     int i;
195     // pos = 0 reserved for length
196     int pos = 1;
197     switch(category){
198         case AVDTP_MEDIA_TRANSPORT:
199         case AVDTP_REPORTING:
200         case AVDTP_DELAY_REPORTING:
201             break;
202         case AVDTP_RECOVERY:
203             buffer[pos++] = caps.recovery.recovery_type; // 0x01=RFC2733
204             buffer[pos++] = caps.recovery.maximum_recovery_window_size;
205             buffer[pos++] = caps.recovery.maximum_number_media_packets;
206             break;
207         case AVDTP_CONTENT_PROTECTION:
208             buffer[pos++] = caps.content_protection.cp_type_value_len + 2;
209             big_endian_store_16(buffer, pos, caps.content_protection.cp_type);
210             pos += 2;
211             (void)memcpy(buffer + pos, caps.content_protection.cp_type_value,
212                          caps.content_protection.cp_type_value_len);
213             pos += caps.content_protection.cp_type_value_len;
214             break;
215         case AVDTP_HEADER_COMPRESSION:
216             buffer[pos++] = (caps.header_compression.back_ch << 7) | (caps.header_compression.media << 6) | (caps.header_compression.recovery << 5);
217             break;
218         case AVDTP_MULTIPLEXING:
219             buffer[pos++] = caps.multiplexing_mode.fragmentation << 7;
220             for (i=0; i<caps.multiplexing_mode.transport_identifiers_num; i++){
221                 buffer[pos++] = caps.multiplexing_mode.transport_session_identifiers[i] << 7;
222                 buffer[pos++] = caps.multiplexing_mode.tcid[i] << 7;
223                 // media, reporting. recovery
224             }
225             break;
226         case AVDTP_MEDIA_CODEC:
227             buffer[pos++] = ((uint8_t)caps.media_codec.media_type) << 4;
228             buffer[pos++] = (uint8_t)caps.media_codec.media_codec_type;
229             for (i = 0; i<caps.media_codec.media_codec_information_len; i++){
230                 buffer[pos++] = caps.media_codec.media_codec_information[i];
231             }
232             break;
233         default:
234             break;
235     }
236     buffer[0] = pos - 1; // length
237     return pos;
238 }
239 
240 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){
241     connection->error_code = 0;
242 
243     if ((category == AVDTP_SERVICE_CATEGORY_INVALID_0) ||
244         ((category == AVDTP_SERVICE_CATEGORY_INVALID_FF) && (signal_identifier == AVDTP_SI_RECONFIGURE))){
245         log_info("    ERROR: BAD SERVICE CATEGORY %d\n", category);
246         connection->reject_service_category = category;
247         connection->error_code = BAD_SERV_CATEGORY;
248         return 1;
249     }
250 
251     if (signal_identifier == AVDTP_SI_RECONFIGURE){
252         if ( (category != AVDTP_CONTENT_PROTECTION) && (category != AVDTP_MEDIA_CODEC)){
253             log_info("    ERROR: REJECT CATEGORY, INVALID_CAPABILITIES\n");
254             connection->reject_service_category = category;
255             connection->error_code = INVALID_CAPABILITIES;
256             return 1;
257         }
258     }
259 
260     switch(category){
261         case AVDTP_MEDIA_TRANSPORT:
262             if (cap_len != 0){
263                 log_info("    ERROR: REJECT CATEGORY, BAD_MEDIA_TRANSPORT\n");
264                 connection->reject_service_category = category;
265                 connection->error_code = BAD_MEDIA_TRANSPORT_FORMAT;
266                 return 1;
267             }
268             break;
269         case AVDTP_REPORTING:
270         case AVDTP_DELAY_REPORTING:
271             if (cap_len != 0){
272                 log_info("    ERROR: REJECT CATEGORY, BAD_LENGTH\n");
273                 connection->reject_service_category = category;
274                 connection->error_code = BAD_LENGTH;
275                 return 1;
276             }
277             break;
278         case AVDTP_RECOVERY:
279             if (cap_len != 3){
280                 log_info("    ERROR: REJECT CATEGORY, BAD_MEDIA_TRANSPORT\n");
281                 connection->reject_service_category = category;
282                 connection->error_code = BAD_RECOVERY_FORMAT;
283                 return 1;
284             }
285             break;
286         case AVDTP_CONTENT_PROTECTION:
287             if (cap_len < 2){
288                 log_info("    ERROR: REJECT CATEGORY, BAD_CP_FORMAT\n");
289                 connection->reject_service_category = category;
290                 connection->error_code = BAD_CP_FORMAT;
291                 return 1;
292             }
293             break;
294         case AVDTP_HEADER_COMPRESSION:
295             // TODO: find error code for bad header compression
296             if (cap_len != 1){
297                 log_info("    ERROR: REJECT CATEGORY, BAD_HEADER_COMPRESSION\n");
298                 connection->reject_service_category = category;
299                 connection->error_code = BAD_RECOVERY_FORMAT;
300                 return 1;
301             }
302             break;
303         case AVDTP_MULTIPLEXING:
304             break;
305         case AVDTP_MEDIA_CODEC:
306             break;
307         default:
308             break;
309     }
310     return 0;
311 }
312 
313 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){
314 
315     int i;
316 
317     uint16_t registered_service_categories = 0;
318     uint16_t to_process = size;
319 
320     while (to_process >= 2){
321 
322         avdtp_service_category_t category = (avdtp_service_category_t) packet[0];
323         uint8_t cap_len = packet[1];
324         packet     += 2;
325         to_process -= 2;
326 
327         if (cap_len > to_process){
328             connection->reject_service_category = category;
329             connection->error_code = BAD_LENGTH;
330             return 0;
331         }
332 
333         if (avdtp_unpack_service_capabilities_has_errors(connection, signal_identifier, category, cap_len)) return 0;
334 
335         int category_valid = 1;
336 
337         uint8_t * data = packet;
338         uint16_t  pos = 0;
339 
340         switch(category){
341             case AVDTP_RECOVERY:
342                 caps->recovery.recovery_type = data[pos++];
343                 caps->recovery.maximum_recovery_window_size = data[pos++];
344                 caps->recovery.maximum_number_media_packets = data[pos++];
345                 break;
346             case AVDTP_CONTENT_PROTECTION:
347                 caps->content_protection.cp_type = big_endian_read_16(data, 0);
348                 caps->content_protection.cp_type_value_len = cap_len - 2;
349                 // connection->reject_service_category = category;
350                 // connection->error_code = UNSUPPORTED_CONFIGURATION;
351                 // support for content protection goes here
352                 break;
353             case AVDTP_HEADER_COMPRESSION:
354                 caps->header_compression.back_ch  = (data[0] >> 7) & 1;
355                 caps->header_compression.media    = (data[0] >> 6) & 1;
356                 caps->header_compression.recovery = (data[0] >> 5) & 1;
357                 break;
358             case AVDTP_MULTIPLEXING:
359                 caps->multiplexing_mode.fragmentation = (data[pos++] >> 7) & 1;
360                 // read [tsid, tcid] for media, reporting. recovery respectively
361                 caps->multiplexing_mode.transport_identifiers_num = 3;
362                 for (i=0; i<caps->multiplexing_mode.transport_identifiers_num; i++){
363                     caps->multiplexing_mode.transport_session_identifiers[i] = (data[pos++] >> 7) & 1;
364                     caps->multiplexing_mode.tcid[i] = (data[pos++] >> 7) & 1;
365                 }
366                 break;
367             case AVDTP_MEDIA_CODEC:
368                 caps->media_codec.media_type = (avdtp_media_type_t)(data[pos++] >> 4);
369                 caps->media_codec.media_codec_type = (avdtp_media_codec_type_t)(data[pos++]);
370                 caps->media_codec.media_codec_information_len = cap_len - 2;
371                 caps->media_codec.media_codec_information = &data[pos++];
372                 break;
373             case AVDTP_MEDIA_TRANSPORT:
374             case AVDTP_REPORTING:
375             case AVDTP_DELAY_REPORTING:
376                 break;
377             default:
378                 category_valid = 0;
379                 break;
380         }
381 
382         if (category_valid) {
383             registered_service_categories = store_bit16(registered_service_categories, category, 1);
384         }
385 
386         packet     += cap_len;
387         to_process -= cap_len;
388     }
389 
390     return registered_service_categories;
391 }
392 
393 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){
394     if (signaling_packet->offset) return;
395     bool basic_capabilities_only = false;
396     signaling_packet->message_type = AVDTP_RESPONSE_ACCEPT_MSG;
397     int i;
398 
399     signaling_packet->size = 0;
400     memset(signaling_packet->command, 0 , sizeof(signaling_packet->command));
401 
402     switch (identifier) {
403         case AVDTP_SI_GET_CAPABILITIES:
404             basic_capabilities_only = true;
405             break;
406         case AVDTP_SI_GET_ALL_CAPABILITIES:
407             break;
408         case AVDTP_SI_SET_CONFIGURATION:
409             signaling_packet->command[signaling_packet->size++] = signaling_packet->acp_seid << 2;
410             signaling_packet->command[signaling_packet->size++] = signaling_packet->int_seid << 2;
411             signaling_packet->message_type = AVDTP_CMD_MSG;
412             break;
413         case AVDTP_SI_RECONFIGURE:
414             signaling_packet->command[signaling_packet->size++] = signaling_packet->acp_seid << 2;
415             signaling_packet->message_type = AVDTP_CMD_MSG;
416             break;
417         default:
418             log_error("avdtp_prepare_capabilities wrong identifier %d", identifier);
419             break;
420     }
421 
422     for (i = AVDTP_MEDIA_TRANSPORT; i <= AVDTP_DELAY_REPORTING; i++){
423         int registered_category = get_bit16(service_categories, i);
424         if (!registered_category && (identifier == AVDTP_SI_SET_CONFIGURATION)){
425             // TODO: introduce bitmap of mandatory categories
426             if (i == AVDTP_MEDIA_TRANSPORT){
427                 registered_category = true;
428             }
429         }
430         // AVDTP_SI_GET_CAPABILITIES reports only basic capabilities (i.e., it skips non-basic categories)
431         if (basic_capabilities_only && !avdtp_is_basic_capability(i)){
432             registered_category = false;
433         }
434 
435         if (registered_category){
436             // service category
437             signaling_packet->command[signaling_packet->size++] = i;
438             signaling_packet->size += avdtp_pack_service_capabilities(signaling_packet->command + signaling_packet->size,
439                     sizeof(signaling_packet->command) - signaling_packet->size, capabilities, (avdtp_service_category_t) i);
440         }
441     }
442     signaling_packet->signal_identifier = (avdtp_signal_identifier_t)identifier;
443     signaling_packet->transaction_label = transaction_label;
444 }
445 
446 int avdtp_signaling_create_fragment(uint16_t cid, avdtp_signaling_packet_t * signaling_packet, uint8_t * out_buffer) {
447     int mtu = l2cap_get_remote_mtu_for_local_cid(cid);
448     int data_len = 0;
449 
450     uint16_t offset = signaling_packet->offset;
451     uint16_t pos = 1;
452 
453     if (offset == 0){
454         if (signaling_packet->size <= (mtu - 2)){
455             signaling_packet->packet_type = AVDTP_SINGLE_PACKET;
456             out_buffer[pos++] = signaling_packet->signal_identifier;
457             data_len = signaling_packet->size;
458         } else {
459             signaling_packet->packet_type = AVDTP_START_PACKET;
460             out_buffer[pos++] = (mtu + signaling_packet->size)/ (mtu-1);
461             out_buffer[pos++] = signaling_packet->signal_identifier;
462             data_len = mtu - 3;
463             signaling_packet->offset = data_len;
464         }
465     } else {
466         int remaining_bytes = signaling_packet->size - offset;
467         if (remaining_bytes <= (mtu - 1)){
468             signaling_packet->packet_type = AVDTP_END_PACKET;
469             data_len = remaining_bytes;
470             signaling_packet->offset = 0;
471         } else{
472             signaling_packet->packet_type = AVDTP_CONTINUE_PACKET;
473             data_len = mtu - 1;
474             signaling_packet->offset += data_len;
475         }
476     }
477     out_buffer[0] = avdtp_header(signaling_packet->transaction_label, signaling_packet->packet_type, signaling_packet->message_type);
478     (void)memcpy(out_buffer + pos, signaling_packet->command + offset,
479                  data_len);
480     pos += data_len;
481     return pos;
482 }
483 
484 
485 void avdtp_signaling_emit_connection_established(uint16_t avdtp_cid, bd_addr_t addr, uint8_t status) {
486     uint8_t event[12];
487     int pos = 0;
488     event[pos++] = HCI_EVENT_AVDTP_META;
489     event[pos++] = sizeof(event) - 2;
490     event[pos++] = AVDTP_SUBEVENT_SIGNALING_CONNECTION_ESTABLISHED;
491     little_endian_store_16(event, pos, avdtp_cid);
492     pos += 2;
493     reverse_bd_addr(addr,&event[pos]);
494     pos += 6;
495     event[pos++] = status;
496     avdtp_emit_sink_and_source(event, pos);
497 }
498 
499 void avdtp_signaling_emit_connection_released(uint16_t avdtp_cid) {
500     uint8_t event[5];
501     int pos = 0;
502     event[pos++] = HCI_EVENT_AVDTP_META;
503     event[pos++] = sizeof(event) - 2;
504     event[pos++] = AVDTP_SUBEVENT_SIGNALING_CONNECTION_RELEASED;
505     little_endian_store_16(event, pos, avdtp_cid);
506     pos += 2;
507     avdtp_emit_sink_and_source(event, pos);
508 }
509 
510 void avdtp_signaling_emit_sep(uint16_t avdtp_cid, avdtp_sep_t sep) {
511     uint8_t event[9];
512     int pos = 0;
513     event[pos++] = HCI_EVENT_AVDTP_META;
514     event[pos++] = sizeof(event) - 2;
515     event[pos++] = AVDTP_SUBEVENT_SIGNALING_SEP_FOUND;
516     little_endian_store_16(event, pos, avdtp_cid);
517     pos += 2;
518     event[pos++] = sep.seid;
519     event[pos++] = sep.in_use;
520     event[pos++] = sep.media_type;
521     event[pos++] = sep.type;
522     avdtp_emit_sink_and_source(event, pos);
523 }
524 
525 void avdtp_signaling_emit_sep_done(uint16_t avdtp_cid) {
526     uint8_t event[5];
527     int pos = 0;
528     event[pos++] = HCI_EVENT_AVDTP_META;
529     event[pos++] = sizeof(event) - 2;
530     event[pos++] = AVDTP_SUBEVENT_SIGNALING_SEP_DICOVERY_DONE;
531     little_endian_store_16(event, pos, avdtp_cid);
532     pos += 2;
533     avdtp_emit_sink_and_source(event, pos);
534 }
535 
536 void avdtp_signaling_emit_accept(uint16_t avdtp_cid, uint8_t local_seid, avdtp_signal_identifier_t identifier, bool is_initiator) {
537     uint8_t event[8];
538     int pos = 0;
539     event[pos++] = HCI_EVENT_AVDTP_META;
540     event[pos++] = sizeof(event) - 2;
541     event[pos++] = AVDTP_SUBEVENT_SIGNALING_ACCEPT;
542     little_endian_store_16(event, pos, avdtp_cid);
543     pos += 2;
544     event[pos++] = local_seid;
545     event[pos++] = is_initiator ? 1 : 0;
546     event[pos++] = identifier;
547     avdtp_emit_sink_and_source(event, pos);
548 }
549 
550 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){
551     uint8_t event[8];
552     int pos = 0;
553     event[pos++] = HCI_EVENT_AVDTP_META;
554     event[pos++] = sizeof(event) - 2;
555     event[pos++] = AVDTP_SUBEVENT_SIGNALING_ACCEPT;
556     little_endian_store_16(event, pos, stream_endpoint->connection->avdtp_cid);
557     pos += 2;
558     event[pos++] = local_seid;
559     event[pos++] = is_initiator ? 1 : 0;
560     event[pos++] = identifier;
561 
562     btstack_packet_handler_t packet_handler = avdtp_packet_handler_for_stream_endpoint(stream_endpoint);
563     (*packet_handler)(HCI_EVENT_PACKET, 0, event, pos);
564 }
565 
566 void avdtp_signaling_emit_reject(uint16_t avdtp_cid, uint8_t local_seid, avdtp_signal_identifier_t identifier, bool is_initiator) {
567     uint8_t event[8];
568     int pos = 0;
569     event[pos++] = HCI_EVENT_AVDTP_META;
570     event[pos++] = sizeof(event) - 2;
571     event[pos++] = AVDTP_SUBEVENT_SIGNALING_REJECT;
572     little_endian_store_16(event, pos, avdtp_cid);
573     pos += 2;
574     event[pos++] = local_seid;
575     event[pos++] = is_initiator ? 1 : 0;
576     event[pos++] = identifier;
577     avdtp_emit_sink_and_source(event, pos);
578 }
579 
580 void avdtp_signaling_emit_general_reject(uint16_t avdtp_cid, uint8_t local_seid, avdtp_signal_identifier_t identifier, bool is_initiator) {
581     uint8_t event[8];
582     int pos = 0;
583     event[pos++] = HCI_EVENT_AVDTP_META;
584     event[pos++] = sizeof(event) - 2;
585     event[pos++] = AVDTP_SUBEVENT_SIGNALING_GENERAL_REJECT;
586     little_endian_store_16(event, pos, avdtp_cid);
587     pos += 2;
588     event[pos++] = local_seid;
589     event[pos++] = is_initiator ? 1 : 0;
590     event[pos++] = identifier;
591     avdtp_emit_sink_and_source(event, pos);
592 }
593 
594 static inline void
595 avdtp_signaling_emit_capability(uint8_t capability_subevent_id, uint16_t avdtp_cid, uint8_t local_seid, uint8_t remote_seid) {
596     uint8_t event[7];
597     int pos = 0;
598     event[pos++] = HCI_EVENT_AVDTP_META;
599     event[pos++] = sizeof(event) - 2;
600     event[pos++] = capability_subevent_id;
601     little_endian_store_16(event, pos, avdtp_cid);
602     pos += 2;
603     event[pos++] = local_seid;
604     event[pos++] = remote_seid;
605     avdtp_emit_sink_and_source(event, pos);
606 }
607 
608 static void avdtp_signaling_emit_media_codec_sbc_capability(uint16_t avdtp_cid, uint8_t local_seid, uint8_t remote_seid,
609                                                             adtvp_media_codec_capabilities_t media_codec) {
610     uint8_t event[15];
611     int pos = 0;
612     event[pos++] = HCI_EVENT_AVDTP_META;
613     event[pos++] = sizeof(event) - 2;
614     event[pos++] = AVDTP_SUBEVENT_SIGNALING_MEDIA_CODEC_SBC_CAPABILITY;
615     little_endian_store_16(event, pos, avdtp_cid);
616     pos += 2;
617     event[pos++] = local_seid;
618     event[pos++] = remote_seid;
619     event[pos++] = media_codec.media_type;
620     event[pos++] = media_codec.media_codec_information[0] >> 4;
621     event[pos++] = media_codec.media_codec_information[0] & 0x0F;
622     event[pos++] = media_codec.media_codec_information[1] >> 4;
623     event[pos++] = (media_codec.media_codec_information[1] & 0x0F) >> 2;
624     event[pos++] = media_codec.media_codec_information[1] & 0x03;
625     event[pos++] = media_codec.media_codec_information[2];
626     event[pos++] = media_codec.media_codec_information[3];
627     avdtp_emit_sink_and_source(event, pos);
628 }
629 
630 static void avdtp_signaling_emit_media_codec_other_capability(uint16_t avdtp_cid, uint8_t local_seid, uint8_t remote_seid,
631                                                   adtvp_media_codec_capabilities_t media_codec) {
632     uint8_t event[MAX_MEDIA_CODEC_INFORMATION_LENGTH + 12];
633     int pos = 0;
634     event[pos++] = HCI_EVENT_AVDTP_META;
635     event[pos++] = sizeof(event) - 2;
636     event[pos++] = AVDTP_SUBEVENT_SIGNALING_MEDIA_CODEC_OTHER_CAPABILITY;
637     little_endian_store_16(event, pos, avdtp_cid);
638     pos += 2;
639     event[pos++] = local_seid;
640     event[pos++] = remote_seid;
641     event[pos++] = media_codec.media_type;
642     little_endian_store_16(event, pos, media_codec.media_codec_type);
643     pos += 2;
644     little_endian_store_16(event, pos, media_codec.media_codec_information_len);
645     pos += 2;
646     (void)memcpy(event + pos, media_codec.media_codec_information,
647                  btstack_min(media_codec.media_codec_information_len, MAX_MEDIA_CODEC_INFORMATION_LENGTH));
648     avdtp_emit_sink_and_source(event, pos);
649 }
650 
651 static void
652 avdtp_signaling_emit_media_transport_capability(uint16_t avdtp_cid, uint8_t local_seid, uint8_t remote_seid) {
653     avdtp_signaling_emit_capability(AVDTP_SUBEVENT_SIGNALING_MEDIA_TRANSPORT_CAPABILITY, avdtp_cid, local_seid,
654                                     remote_seid);
655 }
656 
657 static void avdtp_signaling_emit_reporting_capability(uint16_t avdtp_cid, uint8_t local_seid, uint8_t remote_seid) {
658     avdtp_signaling_emit_capability(AVDTP_SUBEVENT_SIGNALING_REPORTING_CAPABILITY, avdtp_cid, local_seid, remote_seid);
659 }
660 
661 static void
662 avdtp_signaling_emit_delay_reporting_capability(uint16_t avdtp_cid, uint8_t local_seid, uint8_t remote_seid) {
663     avdtp_signaling_emit_capability(AVDTP_SUBEVENT_SIGNALING_DELAY_REPORTING_CAPABILITY, avdtp_cid, local_seid,
664                                     remote_seid);
665 }
666 
667 static void avdtp_signaling_emit_recovery_capability(uint16_t avdtp_cid, uint8_t local_seid, uint8_t remote_seid,
668                                                      avdtp_recovery_capabilities_t *recovery) {
669     uint8_t event[10];
670     int pos = 0;
671     event[pos++] = HCI_EVENT_AVDTP_META;
672     event[pos++] = sizeof(event) - 2;
673     event[pos++] = AVDTP_SUBEVENT_SIGNALING_RECOVERY_CAPABILITY;
674     little_endian_store_16(event, pos, avdtp_cid);
675     pos += 2;
676     event[pos++] = local_seid;
677     event[pos++] = remote_seid;
678     event[pos++] = recovery->recovery_type;
679     event[pos++] = recovery->maximum_recovery_window_size;
680     event[pos++] = recovery->maximum_number_media_packets;
681     avdtp_emit_sink_and_source(event, pos);
682 }
683 
684 static void
685 avdtp_signaling_emit_content_protection_capability(uint16_t avdtp_cid, uint8_t local_seid, uint8_t remote_seid,
686                                                    adtvp_content_protection_t *content_protection) {
687     uint8_t event[22];
688     int pos = 0;
689     event[pos++] = HCI_EVENT_AVDTP_META;
690     event[pos++] = sizeof(event) - 2;
691     event[pos++] = AVDTP_SUBEVENT_SIGNALING_CONTENT_PROTECTION_CAPABILITY;
692     little_endian_store_16(event, pos, avdtp_cid);
693     pos += 2;
694     event[pos++] = local_seid;
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 local_seid, uint8_t remote_seid,
713                                                    avdtp_header_compression_capabilities_t *header_compression) {
714     uint8_t event[10];
715     int pos = 0;
716     event[pos++] = HCI_EVENT_AVDTP_META;
717     event[pos++] = sizeof(event) - 2;
718     event[pos++] = AVDTP_SUBEVENT_SIGNALING_HEADER_COMPRESSION_CAPABILITY;
719     little_endian_store_16(event, pos, avdtp_cid);
720     pos += 2;
721     event[pos++] = local_seid;
722     event[pos++] = remote_seid;
723     event[pos++] = header_compression->back_ch;
724     event[pos++] = header_compression->media;
725     event[pos++] = header_compression->recovery;
726     avdtp_emit_sink_and_source(event, pos);
727 }
728 
729 static void
730 avdtp_signaling_emit_content_multiplexing_capability(uint16_t avdtp_cid, uint8_t local_seid, uint8_t remote_seid,
731                                                      avdtp_multiplexing_mode_capabilities_t *multiplexing_mode) {
732     uint8_t event[15];
733     int pos = 0;
734     event[pos++] = HCI_EVENT_AVDTP_META;
735     event[pos++] = sizeof(event) - 2;
736     event[pos++] = AVDTP_SUBEVENT_SIGNALING_MULTIPLEXING_CAPABILITY;
737     little_endian_store_16(event, pos, avdtp_cid);
738     pos += 2;
739     event[pos++] = local_seid;
740     event[pos++] = remote_seid;
741 
742     event[pos++] = multiplexing_mode->fragmentation;
743     event[pos++] = multiplexing_mode->transport_identifiers_num;
744 
745     int i;
746     for (i = 0; i < 3; i++){
747         event[pos++] = multiplexing_mode->transport_session_identifiers[i];
748     }
749     for (i = 0; i < 3; i++){
750         event[pos++] = multiplexing_mode->tcid[i];
751     }
752     avdtp_emit_sink_and_source(event, pos);
753 }
754 
755 static void avdtp_signaling_emit_capability_done(uint16_t avdtp_cid, uint8_t local_seid, uint8_t remote_seid) {
756     uint8_t event[7];
757     int pos = 0;
758     event[pos++] = HCI_EVENT_AVDTP_META;
759     event[pos++] = sizeof(event) - 2;
760     event[pos++] = AVDTP_SUBEVENT_SIGNALING_CAPABILITIES_DONE;
761     little_endian_store_16(event, pos, avdtp_cid);
762     pos += 2;
763     event[pos++] = local_seid;
764     event[pos++] = remote_seid;
765     avdtp_emit_sink_and_source(event, pos);
766 }
767 
768 // emit events for all capabilities incl. final done event
769 void avdtp_signaling_emit_capabilities(uint16_t avdtp_cid, uint8_t local_seid, uint8_t remote_seid, avdtp_capabilities_t *capabilities,
770                                        uint16_t registered_service_categories) {
771     if (get_bit16(registered_service_categories, AVDTP_MEDIA_CODEC)){
772         switch (capabilities->media_codec.media_codec_type){
773             case AVDTP_CODEC_SBC:
774                 avdtp_signaling_emit_media_codec_sbc_capability(avdtp_cid, local_seid, remote_seid, capabilities->media_codec);
775                 break;
776             default:
777                 avdtp_signaling_emit_media_codec_other_capability(avdtp_cid, local_seid, remote_seid, capabilities->media_codec);
778                 break;
779         }
780     }
781 
782     if (get_bit16(registered_service_categories, AVDTP_MEDIA_TRANSPORT)){
783         avdtp_signaling_emit_media_transport_capability(avdtp_cid, local_seid, remote_seid);
784     }
785     if (get_bit16(registered_service_categories, AVDTP_REPORTING)){
786         avdtp_signaling_emit_reporting_capability(avdtp_cid, local_seid, remote_seid);
787     }
788     if (get_bit16(registered_service_categories, AVDTP_RECOVERY)){
789         avdtp_signaling_emit_recovery_capability(avdtp_cid, local_seid, remote_seid, &capabilities->recovery);
790     }
791     if (get_bit16(registered_service_categories, AVDTP_CONTENT_PROTECTION)){
792         avdtp_signaling_emit_content_protection_capability(avdtp_cid, local_seid, remote_seid,
793                                                            &capabilities->content_protection);
794     }
795     if (get_bit16(registered_service_categories, AVDTP_HEADER_COMPRESSION)){
796         avdtp_signaling_emit_header_compression_capability(avdtp_cid, local_seid, remote_seid,
797                                                            &capabilities->header_compression);
798     }
799     if (get_bit16(registered_service_categories, AVDTP_MULTIPLEXING)){
800         avdtp_signaling_emit_content_multiplexing_capability(avdtp_cid, local_seid, remote_seid,
801                                                              &capabilities->multiplexing_mode);
802     }
803     if (get_bit16(registered_service_categories, AVDTP_DELAY_REPORTING)){
804         avdtp_signaling_emit_delay_reporting_capability(avdtp_cid, local_seid, remote_seid);
805     }
806     avdtp_signaling_emit_capability_done(avdtp_cid, local_seid, remote_seid);
807 }
808 
809 static void avdtp_signaling_emit_media_codec_sbc(avdtp_stream_endpoint_t *stream_endpoint, uint16_t avdtp_cid,
810                                      avdtp_media_type_t media_type, const uint8_t *media_codec_information,
811                                      uint8_t reconfigure) {
812 
813     btstack_packet_handler_t packet_handler = avdtp_packet_handler_for_stream_endpoint(stream_endpoint);
814     uint8_t local_seid = avdtp_local_seid(stream_endpoint);
815     uint8_t remote_seid = avdtp_remote_seid(stream_endpoint);
816 
817     uint8_t event[16 + 2];
818     int pos = 0;
819     event[pos++] = HCI_EVENT_AVDTP_META;
820     event[pos++] = sizeof(event) - 2;
821 
822     event[pos++] = AVDTP_SUBEVENT_SIGNALING_MEDIA_CODEC_SBC_CONFIGURATION;
823     little_endian_store_16(event, pos, avdtp_cid);
824     pos += 2;
825     event[pos++] = local_seid;
826     event[pos++] = remote_seid;
827     event[pos++] = reconfigure;
828 
829 
830     uint8_t sampling_frequency_bitmap = media_codec_information[0] >> 4;
831     uint8_t channel_mode_bitmap = media_codec_information[0] & 0x0F;
832     uint8_t block_length_bitmap = media_codec_information[1] >> 4;
833     uint8_t subbands_bitmap = (media_codec_information[1] & 0x0F) >> 2;
834 
835     uint8_t num_channels = 0;
836     if ((channel_mode_bitmap & AVDTP_SBC_JOINT_STEREO) ||
837         (channel_mode_bitmap & AVDTP_SBC_STEREO) ||
838         (channel_mode_bitmap & AVDTP_SBC_DUAL_CHANNEL)) {
839         num_channels = 2;
840     } else if (channel_mode_bitmap & AVDTP_SBC_MONO) {
841         num_channels = 1;
842     }
843 
844     uint16_t sampling_frequency = 0;
845     if (sampling_frequency_bitmap & AVDTP_SBC_48000) {
846         sampling_frequency = 48000;
847     } else if (sampling_frequency_bitmap & AVDTP_SBC_44100) {
848         sampling_frequency = 44100;
849     } else if (sampling_frequency_bitmap & AVDTP_SBC_32000) {
850         sampling_frequency = 32000;
851     } else if (sampling_frequency_bitmap & AVDTP_SBC_16000) {
852         sampling_frequency = 16000;
853     }
854 
855     uint8_t subbands = 0;
856     if (subbands_bitmap & AVDTP_SBC_SUBBANDS_8){
857         subbands = 8;
858     } else if (subbands_bitmap & AVDTP_SBC_SUBBANDS_4){
859         subbands = 4;
860     }
861 
862     uint8_t block_length = 0;
863     if (block_length_bitmap & AVDTP_SBC_BLOCK_LENGTH_16){
864         block_length = 16;
865     } else if (block_length_bitmap & AVDTP_SBC_BLOCK_LENGTH_12){
866         block_length = 12;
867     } else if (block_length_bitmap & AVDTP_SBC_BLOCK_LENGTH_8){
868         block_length = 8;
869     } else if (block_length_bitmap & AVDTP_SBC_BLOCK_LENGTH_4){
870         block_length = 4;
871     }
872 
873     event[pos++] = media_type;
874     little_endian_store_16(event, pos, sampling_frequency);
875     pos += 2;
876 
877     event[pos++] = channel_mode_bitmap;
878     event[pos++] = num_channels;
879     event[pos++] = block_length;
880     event[pos++] = subbands;
881     event[pos++] = media_codec_information[1] & 0x03;
882     event[pos++] = media_codec_information[2];
883     event[pos++] = media_codec_information[3];
884     (*packet_handler)(HCI_EVENT_PACKET, 0, event, sizeof(event));
885 }
886 
887 static void avdtp_signaling_emit_media_codec_other(avdtp_stream_endpoint_t *stream_endpoint, uint16_t avdtp_cid,
888                                        adtvp_media_codec_capabilities_t * media_codec, uint8_t reconfigure) {
889 
890     btstack_packet_handler_t packet_handler = avdtp_packet_handler_for_stream_endpoint(stream_endpoint);
891     uint8_t local_seid = avdtp_local_seid(stream_endpoint);
892     uint8_t remote_seid = avdtp_remote_seid(stream_endpoint);
893 
894     uint8_t event[MAX_MEDIA_CODEC_INFORMATION_LENGTH + 13];
895     int pos = 0;
896     event[pos++] = HCI_EVENT_AVDTP_META;
897     event[pos++] = sizeof(event) - 2;
898     event[pos++] = AVDTP_SUBEVENT_SIGNALING_MEDIA_CODEC_OTHER_CONFIGURATION;
899     little_endian_store_16(event, pos, avdtp_cid);
900     pos += 2;
901     event[pos++] = local_seid;
902     event[pos++] = remote_seid;
903     event[pos++] = reconfigure;
904     event[pos++] = media_codec->media_type;
905     little_endian_store_16(event, pos, media_codec->media_codec_type);
906     pos += 2;
907     little_endian_store_16(event, pos, media_codec->media_codec_information_len);
908     pos += 2;
909 
910     int media_codec_len = btstack_min(MAX_MEDIA_CODEC_INFORMATION_LENGTH, media_codec->media_codec_information_len);
911     (void)memcpy(event + pos, media_codec->media_codec_information, media_codec_len);
912 
913     (*packet_handler)(HCI_EVENT_PACKET, 0, event, sizeof(event));
914 }
915 
916 void avdtp_signaling_emit_delay(uint16_t avdtp_cid, uint8_t local_seid, uint16_t delay) {
917     uint8_t event[8];
918     int pos = 0;
919     event[pos++] = HCI_EVENT_AVDTP_META;
920     event[pos++] = sizeof(event) - 2;
921     event[pos++] = AVDTP_SUBEVENT_SIGNALING_DELAY_REPORT;
922     little_endian_store_16(event, pos, avdtp_cid);
923     pos += 2;
924     event[pos++] = local_seid;
925     little_endian_store_16(event, pos, delay);
926     pos += 2;
927     avdtp_emit_source(event, sizeof(event));
928 }
929 
930 void avdtp_signaling_emit_media_codec_sbc_configuration(avdtp_stream_endpoint_t *stream_endpoint, uint16_t avdtp_cid,
931                                                         avdtp_media_type_t media_type,
932                                                         const uint8_t *media_codec_information) {
933     avdtp_signaling_emit_media_codec_sbc(stream_endpoint, avdtp_cid, media_type,
934                                          media_codec_information, 0);
935 }
936 
937 void avdtp_signaling_emit_media_codec_other_configuration(avdtp_stream_endpoint_t *stream_endpoint, uint16_t avdtp_cid,
938                                                           adtvp_media_codec_capabilities_t * media_codec) {
939     avdtp_signaling_emit_media_codec_other(stream_endpoint, avdtp_cid, media_codec, 0);
940 }
941 
942 void avdtp_signaling_emit_configuration(avdtp_stream_endpoint_t *stream_endpoint, uint16_t avdtp_cid,
943                                         avdtp_capabilities_t *configuration, uint16_t configured_service_categories) {
944 
945     if (get_bit16(configured_service_categories, AVDTP_MEDIA_CODEC)){
946         switch (configuration->media_codec.media_codec_type){
947             case AVDTP_CODEC_SBC:
948                 avdtp_signaling_emit_media_codec_sbc_configuration(
949                         stream_endpoint, avdtp_cid,
950                         configuration->media_codec.media_type,
951                         configuration->media_codec.media_codec_information);
952                 break;
953             default:
954                 avdtp_signaling_emit_media_codec_other_configuration(stream_endpoint, avdtp_cid,
955                                                                      &configuration->media_codec);
956                 break;
957         }
958     }
959 }
960 
961 void avdtp_streaming_emit_connection_established(avdtp_stream_endpoint_t *stream_endpoint, uint8_t status) {
962     uint8_t event[14];
963     int pos = 0;
964     event[pos++] = HCI_EVENT_AVDTP_META;
965     event[pos++] = sizeof(event) - 2;
966     event[pos++] = AVDTP_SUBEVENT_STREAMING_CONNECTION_ESTABLISHED;
967     little_endian_store_16(event, pos, stream_endpoint->connection->avdtp_cid);
968     pos += 2;
969     reverse_bd_addr(stream_endpoint->connection->remote_addr, &event[pos]);
970     pos += 6;
971     event[pos++] = avdtp_local_seid(stream_endpoint);
972     event[pos++] = avdtp_remote_seid(stream_endpoint);
973     event[pos++] = status;
974 
975     btstack_packet_handler_t packet_handler = avdtp_packet_handler_for_stream_endpoint(stream_endpoint);
976     (*packet_handler)(HCI_EVENT_PACKET, 0, event, sizeof(event));
977 }
978 
979 void avdtp_streaming_emit_connection_released(avdtp_stream_endpoint_t *stream_endpoint, uint16_t avdtp_cid, uint8_t local_seid) {
980     uint8_t event[6];
981     int pos = 0;
982     event[pos++] = HCI_EVENT_AVDTP_META;
983     event[pos++] = sizeof(event) - 2;
984     event[pos++] = AVDTP_SUBEVENT_STREAMING_CONNECTION_RELEASED;
985     little_endian_store_16(event, pos, avdtp_cid);
986     pos += 2;
987     event[pos++] = local_seid;
988 
989     btstack_packet_handler_t packet_handler = avdtp_packet_handler_for_stream_endpoint(stream_endpoint);
990     (*packet_handler)(HCI_EVENT_PACKET, 0, event, sizeof(event));
991 }
992 
993 void avdtp_streaming_emit_can_send_media_packet_now(avdtp_stream_endpoint_t *stream_endpoint, uint16_t sequence_number) {
994     uint8_t event[8];
995     int pos = 0;
996     event[pos++] = HCI_EVENT_AVDTP_META;
997     event[pos++] = sizeof(event) - 2;
998     event[pos++] = AVDTP_SUBEVENT_STREAMING_CAN_SEND_MEDIA_PACKET_NOW;
999     little_endian_store_16(event, pos, stream_endpoint->connection->avdtp_cid);
1000     pos += 2;
1001     event[pos++] = avdtp_local_seid(stream_endpoint);
1002     little_endian_store_16(event, pos, sequence_number);
1003     pos += 2;
1004 
1005     btstack_packet_handler_t packet_handler = avdtp_packet_handler_for_stream_endpoint(stream_endpoint);
1006     (*packet_handler)(HCI_EVENT_PACKET, 0, event, sizeof(event));
1007 }
1008 
1009 uint8_t avdtp_request_can_send_now_acceptor(avdtp_connection_t * connection, uint16_t l2cap_cid){
1010     if (!connection) return ERROR_CODE_UNKNOWN_CONNECTION_IDENTIFIER;
1011     connection->wait_to_send_acceptor = 1;
1012     l2cap_request_can_send_now_event(l2cap_cid);
1013     return ERROR_CODE_SUCCESS;
1014 }
1015 
1016 uint8_t avdtp_request_can_send_now_initiator(avdtp_connection_t * connection, uint16_t l2cap_cid){
1017     if (!connection) return ERROR_CODE_UNKNOWN_CONNECTION_IDENTIFIER;
1018     connection->wait_to_send_initiator = 1;
1019     l2cap_request_can_send_now_event(l2cap_cid);
1020     return ERROR_CODE_SUCCESS;
1021 }
1022 
1023 uint8_t avdtp_local_seid(avdtp_stream_endpoint_t * stream_endpoint){
1024     if (!stream_endpoint) return 0;
1025     return stream_endpoint->sep.seid;
1026 
1027 }
1028 
1029 uint8_t avdtp_remote_seid(avdtp_stream_endpoint_t * stream_endpoint){
1030     if (!stream_endpoint) return AVDTP_INVALID_SEP_SEID;
1031     return stream_endpoint->remote_sep.seid;
1032 }
1033 
1034 // helper for A2DP
1035 
1036 void a2dp_replace_subevent_id_and_emit_cmd(btstack_packet_handler_t callback, uint8_t * packet, uint16_t size, uint8_t subevent_id){
1037     UNUSED(size);
1038     btstack_assert(callback != NULL);
1039     packet[0] = HCI_EVENT_A2DP_META;
1040     packet[2] = subevent_id;
1041     (*callback)(HCI_EVENT_PACKET, 0, packet, size);
1042 }
1043 
1044 void a2dp_emit_streaming_connection_established(btstack_packet_handler_t callback, uint8_t * packet, uint16_t size, uint8_t status){
1045     btstack_assert(callback != NULL);
1046     packet[0] = HCI_EVENT_A2DP_META;
1047     packet[2] = A2DP_SUBEVENT_STREAM_ESTABLISHED;
1048     packet[12] = status;
1049     (*callback)(HCI_EVENT_PACKET, 0, packet, size);
1050 }
1051 
1052 void a2dp_emit_signaling_connection_established(btstack_packet_handler_t callback, uint8_t * packet, uint16_t size, uint8_t status){
1053     btstack_assert(callback != NULL);
1054     packet[0] = HCI_EVENT_A2DP_META;
1055     packet[2] = A2DP_SUBEVENT_SIGNALING_CONNECTION_ESTABLISHED;
1056     packet[10] = status;
1057     (*callback)(HCI_EVENT_PACKET, 0, packet, size);
1058 }
1059 
1060 void a2dp_emit_stream_event(btstack_packet_handler_t callback, uint16_t cid, uint8_t local_seid, uint8_t subevent_id){
1061     uint8_t event[6];
1062     int pos = 0;
1063     event[pos++] = HCI_EVENT_A2DP_META;
1064     event[pos++] = sizeof(event) - 2;
1065     event[pos++] = subevent_id;
1066     little_endian_store_16(event, pos, cid);
1067     pos += 2;
1068     event[pos++] = local_seid;
1069     (*callback)(HCI_EVENT_PACKET, 0, event, sizeof(event));
1070 }
1071