xref: /btstack/src/classic/avdtp_util.c (revision 22bed8e12d36d8545a8920fc8ccde6f8821294b0)
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->request_can_send_now = 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, hci_con_handle_t con_handle, uint8_t status) {
486     uint8_t event[14];
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     little_endian_store_16(event, pos, con_handle);
496     pos += 2;
497     event[pos++] = status;
498     avdtp_emit_sink_and_source(event, pos);
499 }
500 
501 void avdtp_signaling_emit_connection_released(uint16_t avdtp_cid) {
502     uint8_t event[5];
503     int pos = 0;
504     event[pos++] = HCI_EVENT_AVDTP_META;
505     event[pos++] = sizeof(event) - 2;
506     event[pos++] = AVDTP_SUBEVENT_SIGNALING_CONNECTION_RELEASED;
507     little_endian_store_16(event, pos, avdtp_cid);
508     pos += 2;
509     avdtp_emit_sink_and_source(event, pos);
510 }
511 
512 void avdtp_signaling_emit_sep(uint16_t avdtp_cid, avdtp_sep_t sep) {
513     uint8_t event[9];
514     int pos = 0;
515     event[pos++] = HCI_EVENT_AVDTP_META;
516     event[pos++] = sizeof(event) - 2;
517     event[pos++] = AVDTP_SUBEVENT_SIGNALING_SEP_FOUND;
518     little_endian_store_16(event, pos, avdtp_cid);
519     pos += 2;
520     event[pos++] = sep.seid;
521     event[pos++] = sep.in_use;
522     event[pos++] = sep.media_type;
523     event[pos++] = sep.type;
524     avdtp_emit_sink_and_source(event, pos);
525 }
526 
527 void avdtp_signaling_emit_sep_done(uint16_t avdtp_cid) {
528     uint8_t event[5];
529     int pos = 0;
530     event[pos++] = HCI_EVENT_AVDTP_META;
531     event[pos++] = sizeof(event) - 2;
532     event[pos++] = AVDTP_SUBEVENT_SIGNALING_SEP_DICOVERY_DONE;
533     little_endian_store_16(event, pos, avdtp_cid);
534     pos += 2;
535     avdtp_emit_sink_and_source(event, pos);
536 }
537 
538 void avdtp_signaling_emit_accept(uint16_t avdtp_cid, uint8_t local_seid, avdtp_signal_identifier_t identifier, bool is_initiator) {
539     uint8_t event[8];
540     int pos = 0;
541     event[pos++] = HCI_EVENT_AVDTP_META;
542     event[pos++] = sizeof(event) - 2;
543     event[pos++] = AVDTP_SUBEVENT_SIGNALING_ACCEPT;
544     little_endian_store_16(event, pos, avdtp_cid);
545     pos += 2;
546     event[pos++] = local_seid;
547     event[pos++] = is_initiator ? 1 : 0;
548     event[pos++] = identifier;
549     avdtp_emit_sink_and_source(event, pos);
550 }
551 
552 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){
553     uint8_t event[8];
554     int pos = 0;
555     event[pos++] = HCI_EVENT_AVDTP_META;
556     event[pos++] = sizeof(event) - 2;
557     event[pos++] = AVDTP_SUBEVENT_SIGNALING_ACCEPT;
558     little_endian_store_16(event, pos, stream_endpoint->connection->avdtp_cid);
559     pos += 2;
560     event[pos++] = local_seid;
561     event[pos++] = is_initiator ? 1 : 0;
562     event[pos++] = identifier;
563 
564     btstack_packet_handler_t packet_handler = avdtp_packet_handler_for_stream_endpoint(stream_endpoint);
565     (*packet_handler)(HCI_EVENT_PACKET, 0, event, pos);
566 }
567 
568 void avdtp_signaling_emit_reject(uint16_t avdtp_cid, uint8_t local_seid, avdtp_signal_identifier_t identifier, bool is_initiator) {
569     uint8_t event[8];
570     int pos = 0;
571     event[pos++] = HCI_EVENT_AVDTP_META;
572     event[pos++] = sizeof(event) - 2;
573     event[pos++] = AVDTP_SUBEVENT_SIGNALING_REJECT;
574     little_endian_store_16(event, pos, avdtp_cid);
575     pos += 2;
576     event[pos++] = local_seid;
577     event[pos++] = is_initiator ? 1 : 0;
578     event[pos++] = identifier;
579     avdtp_emit_sink_and_source(event, pos);
580 }
581 
582 void avdtp_signaling_emit_general_reject(uint16_t avdtp_cid, uint8_t local_seid, avdtp_signal_identifier_t identifier, bool is_initiator) {
583     uint8_t event[8];
584     int pos = 0;
585     event[pos++] = HCI_EVENT_AVDTP_META;
586     event[pos++] = sizeof(event) - 2;
587     event[pos++] = AVDTP_SUBEVENT_SIGNALING_GENERAL_REJECT;
588     little_endian_store_16(event, pos, avdtp_cid);
589     pos += 2;
590     event[pos++] = local_seid;
591     event[pos++] = is_initiator ? 1 : 0;
592     event[pos++] = identifier;
593     avdtp_emit_sink_and_source(event, pos);
594 }
595 
596 static inline void
597 avdtp_signaling_emit_capability(uint8_t capability_subevent_id, uint16_t avdtp_cid, uint8_t local_seid, uint8_t remote_seid) {
598     uint8_t event[7];
599     int pos = 0;
600     event[pos++] = HCI_EVENT_AVDTP_META;
601     event[pos++] = sizeof(event) - 2;
602     event[pos++] = capability_subevent_id;
603     little_endian_store_16(event, pos, avdtp_cid);
604     pos += 2;
605     event[pos++] = local_seid;
606     event[pos++] = remote_seid;
607     avdtp_emit_sink_and_source(event, pos);
608 }
609 
610 static void avdtp_signaling_emit_media_codec_sbc_capability(uint16_t avdtp_cid, uint8_t local_seid, uint8_t remote_seid,
611                                                             adtvp_media_codec_capabilities_t media_codec) {
612     uint8_t event[15];
613     int pos = 0;
614     event[pos++] = HCI_EVENT_AVDTP_META;
615     event[pos++] = sizeof(event) - 2;
616     event[pos++] = AVDTP_SUBEVENT_SIGNALING_MEDIA_CODEC_SBC_CAPABILITY;
617     little_endian_store_16(event, pos, avdtp_cid);
618     pos += 2;
619     event[pos++] = local_seid;
620     event[pos++] = remote_seid;
621     event[pos++] = media_codec.media_type;
622     event[pos++] = media_codec.media_codec_information[0] >> 4;
623     event[pos++] = media_codec.media_codec_information[0] & 0x0F;
624     event[pos++] = media_codec.media_codec_information[1] >> 4;
625     event[pos++] = (media_codec.media_codec_information[1] & 0x0F) >> 2;
626     event[pos++] = media_codec.media_codec_information[1] & 0x03;
627     event[pos++] = media_codec.media_codec_information[2];
628     event[pos++] = media_codec.media_codec_information[3];
629     avdtp_emit_sink_and_source(event, pos);
630 }
631 
632 static void avdtp_signaling_emit_media_codec_other_capability(uint16_t avdtp_cid, uint8_t local_seid, uint8_t remote_seid,
633                                                   adtvp_media_codec_capabilities_t media_codec) {
634     uint8_t event[MAX_MEDIA_CODEC_INFORMATION_LENGTH + 12];
635     int pos = 0;
636     event[pos++] = HCI_EVENT_AVDTP_META;
637     event[pos++] = sizeof(event) - 2;
638     event[pos++] = AVDTP_SUBEVENT_SIGNALING_MEDIA_CODEC_OTHER_CAPABILITY;
639     little_endian_store_16(event, pos, avdtp_cid);
640     pos += 2;
641     event[pos++] = local_seid;
642     event[pos++] = remote_seid;
643     event[pos++] = media_codec.media_type;
644     little_endian_store_16(event, pos, media_codec.media_codec_type);
645     pos += 2;
646     little_endian_store_16(event, pos, media_codec.media_codec_information_len);
647     pos += 2;
648     (void)memcpy(event + pos, media_codec.media_codec_information,
649                  btstack_min(media_codec.media_codec_information_len, MAX_MEDIA_CODEC_INFORMATION_LENGTH));
650     avdtp_emit_sink_and_source(event, pos);
651 }
652 
653 static void
654 avdtp_signaling_emit_media_transport_capability(uint16_t avdtp_cid, uint8_t local_seid, uint8_t remote_seid) {
655     avdtp_signaling_emit_capability(AVDTP_SUBEVENT_SIGNALING_MEDIA_TRANSPORT_CAPABILITY, avdtp_cid, local_seid,
656                                     remote_seid);
657 }
658 
659 static void avdtp_signaling_emit_reporting_capability(uint16_t avdtp_cid, uint8_t local_seid, uint8_t remote_seid) {
660     avdtp_signaling_emit_capability(AVDTP_SUBEVENT_SIGNALING_REPORTING_CAPABILITY, avdtp_cid, local_seid, remote_seid);
661 }
662 
663 static void
664 avdtp_signaling_emit_delay_reporting_capability(uint16_t avdtp_cid, uint8_t local_seid, uint8_t remote_seid) {
665     avdtp_signaling_emit_capability(AVDTP_SUBEVENT_SIGNALING_DELAY_REPORTING_CAPABILITY, avdtp_cid, local_seid,
666                                     remote_seid);
667 }
668 
669 static void avdtp_signaling_emit_recovery_capability(uint16_t avdtp_cid, uint8_t local_seid, uint8_t remote_seid,
670                                                      avdtp_recovery_capabilities_t *recovery) {
671     uint8_t event[10];
672     int pos = 0;
673     event[pos++] = HCI_EVENT_AVDTP_META;
674     event[pos++] = sizeof(event) - 2;
675     event[pos++] = AVDTP_SUBEVENT_SIGNALING_RECOVERY_CAPABILITY;
676     little_endian_store_16(event, pos, avdtp_cid);
677     pos += 2;
678     event[pos++] = local_seid;
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 local_seid, uint8_t remote_seid,
688                                                    adtvp_content_protection_t *content_protection) {
689     uint8_t event[22];
690     int pos = 0;
691     event[pos++] = HCI_EVENT_AVDTP_META;
692     event[pos++] = sizeof(event) - 2;
693     event[pos++] = AVDTP_SUBEVENT_SIGNALING_CONTENT_PROTECTION_CAPABILITY;
694     little_endian_store_16(event, pos, avdtp_cid);
695     pos += 2;
696     event[pos++] = local_seid;
697     event[pos++] = remote_seid;
698 
699     little_endian_store_16(event, pos, content_protection->cp_type);
700     pos += 2;
701     little_endian_store_16(event, pos, content_protection->cp_type_value_len);
702     pos += 2;
703 
704     //TODO: reserve place for value
705     if (content_protection->cp_type_value_len < 10){
706         (void)memcpy(event + pos, content_protection->cp_type_value,
707                      content_protection->cp_type_value_len);
708     }
709     avdtp_emit_sink_and_source(event, pos);
710 }
711 
712 
713 static void
714 avdtp_signaling_emit_header_compression_capability(uint16_t avdtp_cid, uint8_t local_seid, uint8_t remote_seid,
715                                                    avdtp_header_compression_capabilities_t *header_compression) {
716     uint8_t event[10];
717     int pos = 0;
718     event[pos++] = HCI_EVENT_AVDTP_META;
719     event[pos++] = sizeof(event) - 2;
720     event[pos++] = AVDTP_SUBEVENT_SIGNALING_HEADER_COMPRESSION_CAPABILITY;
721     little_endian_store_16(event, pos, avdtp_cid);
722     pos += 2;
723     event[pos++] = local_seid;
724     event[pos++] = remote_seid;
725     event[pos++] = header_compression->back_ch;
726     event[pos++] = header_compression->media;
727     event[pos++] = header_compression->recovery;
728     avdtp_emit_sink_and_source(event, pos);
729 }
730 
731 static void
732 avdtp_signaling_emit_content_multiplexing_capability(uint16_t avdtp_cid, uint8_t local_seid, uint8_t remote_seid,
733                                                      avdtp_multiplexing_mode_capabilities_t *multiplexing_mode) {
734     uint8_t event[15];
735     int pos = 0;
736     event[pos++] = HCI_EVENT_AVDTP_META;
737     event[pos++] = sizeof(event) - 2;
738     event[pos++] = AVDTP_SUBEVENT_SIGNALING_MULTIPLEXING_CAPABILITY;
739     little_endian_store_16(event, pos, avdtp_cid);
740     pos += 2;
741     event[pos++] = local_seid;
742     event[pos++] = remote_seid;
743 
744     event[pos++] = multiplexing_mode->fragmentation;
745     event[pos++] = multiplexing_mode->transport_identifiers_num;
746 
747     int i;
748     for (i = 0; i < 3; i++){
749         event[pos++] = multiplexing_mode->transport_session_identifiers[i];
750     }
751     for (i = 0; i < 3; i++){
752         event[pos++] = multiplexing_mode->tcid[i];
753     }
754     avdtp_emit_sink_and_source(event, pos);
755 }
756 
757 static void avdtp_signaling_emit_capability_done(uint16_t avdtp_cid, uint8_t local_seid, uint8_t remote_seid) {
758     uint8_t event[7];
759     int pos = 0;
760     event[pos++] = HCI_EVENT_AVDTP_META;
761     event[pos++] = sizeof(event) - 2;
762     event[pos++] = AVDTP_SUBEVENT_SIGNALING_CAPABILITIES_DONE;
763     little_endian_store_16(event, pos, avdtp_cid);
764     pos += 2;
765     event[pos++] = local_seid;
766     event[pos++] = remote_seid;
767     avdtp_emit_sink_and_source(event, pos);
768 }
769 
770 // emit events for all capabilities incl. final done event
771 void avdtp_signaling_emit_capabilities(uint16_t avdtp_cid, uint8_t local_seid, uint8_t remote_seid, avdtp_capabilities_t *capabilities,
772                                        uint16_t registered_service_categories) {
773     if (get_bit16(registered_service_categories, AVDTP_MEDIA_CODEC)){
774         switch (capabilities->media_codec.media_codec_type){
775             case AVDTP_CODEC_SBC:
776                 avdtp_signaling_emit_media_codec_sbc_capability(avdtp_cid, local_seid, remote_seid, capabilities->media_codec);
777                 break;
778             default:
779                 avdtp_signaling_emit_media_codec_other_capability(avdtp_cid, local_seid, remote_seid, capabilities->media_codec);
780                 break;
781         }
782     }
783 
784     if (get_bit16(registered_service_categories, AVDTP_MEDIA_TRANSPORT)){
785         avdtp_signaling_emit_media_transport_capability(avdtp_cid, local_seid, remote_seid);
786     }
787     if (get_bit16(registered_service_categories, AVDTP_REPORTING)){
788         avdtp_signaling_emit_reporting_capability(avdtp_cid, local_seid, remote_seid);
789     }
790     if (get_bit16(registered_service_categories, AVDTP_RECOVERY)){
791         avdtp_signaling_emit_recovery_capability(avdtp_cid, local_seid, remote_seid, &capabilities->recovery);
792     }
793     if (get_bit16(registered_service_categories, AVDTP_CONTENT_PROTECTION)){
794         avdtp_signaling_emit_content_protection_capability(avdtp_cid, local_seid, remote_seid,
795                                                            &capabilities->content_protection);
796     }
797     if (get_bit16(registered_service_categories, AVDTP_HEADER_COMPRESSION)){
798         avdtp_signaling_emit_header_compression_capability(avdtp_cid, local_seid, remote_seid,
799                                                            &capabilities->header_compression);
800     }
801     if (get_bit16(registered_service_categories, AVDTP_MULTIPLEXING)){
802         avdtp_signaling_emit_content_multiplexing_capability(avdtp_cid, local_seid, remote_seid,
803                                                              &capabilities->multiplexing_mode);
804     }
805     if (get_bit16(registered_service_categories, AVDTP_DELAY_REPORTING)){
806         avdtp_signaling_emit_delay_reporting_capability(avdtp_cid, local_seid, remote_seid);
807     }
808     avdtp_signaling_emit_capability_done(avdtp_cid, local_seid, remote_seid);
809 }
810 
811 static void avdtp_signaling_emit_media_codec_sbc(avdtp_stream_endpoint_t *stream_endpoint, uint16_t avdtp_cid,
812                                      avdtp_media_type_t media_type, const uint8_t *media_codec_information,
813                                      uint8_t reconfigure) {
814 
815     btstack_packet_handler_t packet_handler = avdtp_packet_handler_for_stream_endpoint(stream_endpoint);
816     uint8_t local_seid = avdtp_local_seid(stream_endpoint);
817     uint8_t remote_seid = avdtp_remote_seid(stream_endpoint);
818 
819     uint8_t event[16 + 2];
820     int pos = 0;
821     event[pos++] = HCI_EVENT_AVDTP_META;
822     event[pos++] = sizeof(event) - 2;
823 
824     event[pos++] = AVDTP_SUBEVENT_SIGNALING_MEDIA_CODEC_SBC_CONFIGURATION;
825     little_endian_store_16(event, pos, avdtp_cid);
826     pos += 2;
827     event[pos++] = local_seid;
828     event[pos++] = remote_seid;
829     event[pos++] = reconfigure;
830 
831 
832     uint8_t sampling_frequency_bitmap = media_codec_information[0] >> 4;
833     uint8_t channel_mode_bitmap = media_codec_information[0] & 0x0F;
834     uint8_t block_length_bitmap = media_codec_information[1] >> 4;
835     uint8_t subbands_bitmap = (media_codec_information[1] & 0x0F) >> 2;
836 
837     uint8_t num_channels = 0;
838     if ((channel_mode_bitmap & AVDTP_SBC_JOINT_STEREO) ||
839         (channel_mode_bitmap & AVDTP_SBC_STEREO) ||
840         (channel_mode_bitmap & AVDTP_SBC_DUAL_CHANNEL)) {
841         num_channels = 2;
842     } else if (channel_mode_bitmap & AVDTP_SBC_MONO) {
843         num_channels = 1;
844     }
845 
846     uint16_t sampling_frequency = 0;
847     if (sampling_frequency_bitmap & AVDTP_SBC_48000) {
848         sampling_frequency = 48000;
849     } else if (sampling_frequency_bitmap & AVDTP_SBC_44100) {
850         sampling_frequency = 44100;
851     } else if (sampling_frequency_bitmap & AVDTP_SBC_32000) {
852         sampling_frequency = 32000;
853     } else if (sampling_frequency_bitmap & AVDTP_SBC_16000) {
854         sampling_frequency = 16000;
855     }
856 
857     uint8_t subbands = 0;
858     if (subbands_bitmap & AVDTP_SBC_SUBBANDS_8){
859         subbands = 8;
860     } else if (subbands_bitmap & AVDTP_SBC_SUBBANDS_4){
861         subbands = 4;
862     }
863 
864     uint8_t block_length = 0;
865     if (block_length_bitmap & AVDTP_SBC_BLOCK_LENGTH_16){
866         block_length = 16;
867     } else if (block_length_bitmap & AVDTP_SBC_BLOCK_LENGTH_12){
868         block_length = 12;
869     } else if (block_length_bitmap & AVDTP_SBC_BLOCK_LENGTH_8){
870         block_length = 8;
871     } else if (block_length_bitmap & AVDTP_SBC_BLOCK_LENGTH_4){
872         block_length = 4;
873     }
874 
875     event[pos++] = media_type;
876     little_endian_store_16(event, pos, sampling_frequency);
877     pos += 2;
878 
879     event[pos++] = channel_mode_bitmap;
880     event[pos++] = num_channels;
881     event[pos++] = block_length;
882     event[pos++] = subbands;
883     event[pos++] = media_codec_information[1] & 0x03;
884     event[pos++] = media_codec_information[2];
885     event[pos++] = media_codec_information[3];
886     (*packet_handler)(HCI_EVENT_PACKET, 0, event, sizeof(event));
887 }
888 
889 static void avdtp_signaling_emit_media_codec_other(avdtp_stream_endpoint_t *stream_endpoint, uint16_t avdtp_cid,
890                                        adtvp_media_codec_capabilities_t * media_codec, uint8_t reconfigure) {
891 
892     btstack_packet_handler_t packet_handler = avdtp_packet_handler_for_stream_endpoint(stream_endpoint);
893     uint8_t local_seid = avdtp_local_seid(stream_endpoint);
894     uint8_t remote_seid = avdtp_remote_seid(stream_endpoint);
895 
896     uint8_t event[MAX_MEDIA_CODEC_INFORMATION_LENGTH + 13];
897     int pos = 0;
898     event[pos++] = HCI_EVENT_AVDTP_META;
899     event[pos++] = sizeof(event) - 2;
900     event[pos++] = AVDTP_SUBEVENT_SIGNALING_MEDIA_CODEC_OTHER_CONFIGURATION;
901     little_endian_store_16(event, pos, avdtp_cid);
902     pos += 2;
903     event[pos++] = local_seid;
904     event[pos++] = remote_seid;
905     event[pos++] = reconfigure;
906     event[pos++] = media_codec->media_type;
907     little_endian_store_16(event, pos, media_codec->media_codec_type);
908     pos += 2;
909     little_endian_store_16(event, pos, media_codec->media_codec_information_len);
910     pos += 2;
911 
912     int media_codec_len = btstack_min(MAX_MEDIA_CODEC_INFORMATION_LENGTH, media_codec->media_codec_information_len);
913     (void)memcpy(event + pos, media_codec->media_codec_information, media_codec_len);
914 
915     (*packet_handler)(HCI_EVENT_PACKET, 0, event, sizeof(event));
916 }
917 
918 void avdtp_signaling_emit_delay(uint16_t avdtp_cid, uint8_t local_seid, uint16_t delay) {
919     uint8_t event[8];
920     int pos = 0;
921     event[pos++] = HCI_EVENT_AVDTP_META;
922     event[pos++] = sizeof(event) - 2;
923     event[pos++] = AVDTP_SUBEVENT_SIGNALING_DELAY_REPORT;
924     little_endian_store_16(event, pos, avdtp_cid);
925     pos += 2;
926     event[pos++] = local_seid;
927     little_endian_store_16(event, pos, delay);
928     pos += 2;
929     avdtp_emit_source(event, sizeof(event));
930 }
931 
932 void avdtp_signaling_emit_media_codec_sbc_configuration(avdtp_stream_endpoint_t *stream_endpoint, uint16_t avdtp_cid,
933                                                         avdtp_media_type_t media_type,
934                                                         const uint8_t *media_codec_information) {
935     avdtp_signaling_emit_media_codec_sbc(stream_endpoint, avdtp_cid, media_type,
936                                          media_codec_information, 0);
937 }
938 
939 void avdtp_signaling_emit_media_codec_other_configuration(avdtp_stream_endpoint_t *stream_endpoint, uint16_t avdtp_cid,
940                                                           adtvp_media_codec_capabilities_t * media_codec) {
941     avdtp_signaling_emit_media_codec_other(stream_endpoint, avdtp_cid, media_codec, 0);
942 }
943 
944 void avdtp_signaling_emit_configuration(avdtp_stream_endpoint_t *stream_endpoint, uint16_t avdtp_cid,
945                                         avdtp_capabilities_t *configuration, uint16_t configured_service_categories) {
946 
947     if (get_bit16(configured_service_categories, AVDTP_MEDIA_CODEC)){
948         switch (configuration->media_codec.media_codec_type){
949             case AVDTP_CODEC_SBC:
950                 avdtp_signaling_emit_media_codec_sbc_configuration(
951                         stream_endpoint, avdtp_cid,
952                         configuration->media_codec.media_type,
953                         configuration->media_codec.media_codec_information);
954                 break;
955             default:
956                 avdtp_signaling_emit_media_codec_other_configuration(stream_endpoint, avdtp_cid,
957                                                                      &configuration->media_codec);
958                 break;
959         }
960     }
961 }
962 
963 void avdtp_streaming_emit_connection_established(avdtp_stream_endpoint_t *stream_endpoint, uint8_t status) {
964     uint8_t event[14];
965     int pos = 0;
966     event[pos++] = HCI_EVENT_AVDTP_META;
967     event[pos++] = sizeof(event) - 2;
968     event[pos++] = AVDTP_SUBEVENT_STREAMING_CONNECTION_ESTABLISHED;
969     little_endian_store_16(event, pos, stream_endpoint->connection->avdtp_cid);
970     pos += 2;
971     reverse_bd_addr(stream_endpoint->connection->remote_addr, &event[pos]);
972     pos += 6;
973     event[pos++] = avdtp_local_seid(stream_endpoint);
974     event[pos++] = avdtp_remote_seid(stream_endpoint);
975     event[pos++] = status;
976 
977     btstack_packet_handler_t packet_handler = avdtp_packet_handler_for_stream_endpoint(stream_endpoint);
978     (*packet_handler)(HCI_EVENT_PACKET, 0, event, sizeof(event));
979 }
980 
981 void avdtp_streaming_emit_connection_released(avdtp_stream_endpoint_t *stream_endpoint, uint16_t avdtp_cid, uint8_t local_seid) {
982     uint8_t event[6];
983     int pos = 0;
984     event[pos++] = HCI_EVENT_AVDTP_META;
985     event[pos++] = sizeof(event) - 2;
986     event[pos++] = AVDTP_SUBEVENT_STREAMING_CONNECTION_RELEASED;
987     little_endian_store_16(event, pos, avdtp_cid);
988     pos += 2;
989     event[pos++] = local_seid;
990 
991     btstack_packet_handler_t packet_handler = avdtp_packet_handler_for_stream_endpoint(stream_endpoint);
992     (*packet_handler)(HCI_EVENT_PACKET, 0, event, sizeof(event));
993 }
994 
995 void avdtp_streaming_emit_can_send_media_packet_now(avdtp_stream_endpoint_t *stream_endpoint, uint16_t sequence_number) {
996     uint8_t event[8];
997     int pos = 0;
998     event[pos++] = HCI_EVENT_AVDTP_META;
999     event[pos++] = sizeof(event) - 2;
1000     event[pos++] = AVDTP_SUBEVENT_STREAMING_CAN_SEND_MEDIA_PACKET_NOW;
1001     little_endian_store_16(event, pos, stream_endpoint->connection->avdtp_cid);
1002     pos += 2;
1003     event[pos++] = avdtp_local_seid(stream_endpoint);
1004     little_endian_store_16(event, pos, sequence_number);
1005     pos += 2;
1006 
1007     btstack_packet_handler_t packet_handler = avdtp_packet_handler_for_stream_endpoint(stream_endpoint);
1008     (*packet_handler)(HCI_EVENT_PACKET, 0, event, sizeof(event));
1009 }
1010 
1011 uint8_t avdtp_request_can_send_now_acceptor(avdtp_connection_t * connection, uint16_t l2cap_cid){
1012     if (!connection) return ERROR_CODE_UNKNOWN_CONNECTION_IDENTIFIER;
1013     connection->wait_to_send_acceptor = 1;
1014     l2cap_request_can_send_now_event(l2cap_cid);
1015     return ERROR_CODE_SUCCESS;
1016 }
1017 
1018 uint8_t avdtp_request_can_send_now_initiator(avdtp_connection_t * connection, uint16_t l2cap_cid){
1019     if (!connection) return ERROR_CODE_UNKNOWN_CONNECTION_IDENTIFIER;
1020     connection->wait_to_send_initiator = 1;
1021     l2cap_request_can_send_now_event(l2cap_cid);
1022     return ERROR_CODE_SUCCESS;
1023 }
1024 
1025 uint8_t avdtp_local_seid(avdtp_stream_endpoint_t * stream_endpoint){
1026     if (!stream_endpoint) return 0;
1027     return stream_endpoint->sep.seid;
1028 
1029 }
1030 
1031 uint8_t avdtp_remote_seid(avdtp_stream_endpoint_t * stream_endpoint){
1032     if (!stream_endpoint) return AVDTP_INVALID_SEP_SEID;
1033     return stream_endpoint->remote_sep.seid;
1034 }
1035 
1036 // helper for A2DP
1037 
1038 void a2dp_replace_subevent_id_and_emit_cmd(btstack_packet_handler_t callback, uint8_t * packet, uint16_t size, uint8_t subevent_id){
1039     UNUSED(size);
1040     btstack_assert(callback != NULL);
1041     packet[0] = HCI_EVENT_A2DP_META;
1042     packet[2] = subevent_id;
1043     (*callback)(HCI_EVENT_PACKET, 0, packet, size);
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