xref: /btstack/src/classic/avdtp_util.c (revision f400efd4c34c2c3d094122d9c99ddcc5357e2a2e)
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             break;
214         case AVDTP_HEADER_COMPRESSION:
215             buffer[pos++] = (caps.header_compression.back_ch << 7) | (caps.header_compression.media << 6) | (caps.header_compression.recovery << 5);
216             break;
217         case AVDTP_MULTIPLEXING:
218             buffer[pos++] = caps.multiplexing_mode.fragmentation << 7;
219             for (i=0; i<caps.multiplexing_mode.transport_identifiers_num; i++){
220                 buffer[pos++] = caps.multiplexing_mode.transport_session_identifiers[i] << 7;
221                 buffer[pos++] = caps.multiplexing_mode.tcid[i] << 7;
222                 // media, reporting. recovery
223             }
224             break;
225         case AVDTP_MEDIA_CODEC:
226             buffer[pos++] = ((uint8_t)caps.media_codec.media_type) << 4;
227             buffer[pos++] = (uint8_t)caps.media_codec.media_codec_type;
228             for (i = 0; i<caps.media_codec.media_codec_information_len; i++){
229                 buffer[pos++] = caps.media_codec.media_codec_information[i];
230             }
231             break;
232         default:
233             break;
234     }
235     buffer[0] = pos - 1; // length
236     return pos;
237 }
238 
239 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){
240     connection->error_code = 0;
241 
242     if ((category == AVDTP_SERVICE_CATEGORY_INVALID_0) ||
243         ((category == AVDTP_SERVICE_CATEGORY_INVALID_FF) && (signal_identifier == AVDTP_SI_RECONFIGURE))){
244         log_info("    ERROR: BAD SERVICE CATEGORY %d\n", category);
245         connection->reject_service_category = category;
246         connection->error_code = BAD_SERV_CATEGORY;
247         return 1;
248     }
249 
250     if (signal_identifier == AVDTP_SI_RECONFIGURE){
251         if ( (category != AVDTP_CONTENT_PROTECTION) && (category != AVDTP_MEDIA_CODEC)){
252             log_info("    ERROR: REJECT CATEGORY, INVALID_CAPABILITIES\n");
253             connection->reject_service_category = category;
254             connection->error_code = INVALID_CAPABILITIES;
255             return 1;
256         }
257     }
258 
259     switch(category){
260         case AVDTP_MEDIA_TRANSPORT:
261             if (cap_len != 0){
262                 log_info("    ERROR: REJECT CATEGORY, BAD_MEDIA_TRANSPORT\n");
263                 connection->reject_service_category = category;
264                 connection->error_code = BAD_MEDIA_TRANSPORT_FORMAT;
265                 return 1;
266             }
267             break;
268         case AVDTP_REPORTING:
269         case AVDTP_DELAY_REPORTING:
270             if (cap_len != 0){
271                 log_info("    ERROR: REJECT CATEGORY, BAD_LENGTH\n");
272                 connection->reject_service_category = category;
273                 connection->error_code = BAD_LENGTH;
274                 return 1;
275             }
276             break;
277         case AVDTP_RECOVERY:
278             if (cap_len != 3){
279                 log_info("    ERROR: REJECT CATEGORY, BAD_MEDIA_TRANSPORT\n");
280                 connection->reject_service_category = category;
281                 connection->error_code = BAD_RECOVERY_FORMAT;
282                 return 1;
283             }
284             break;
285         case AVDTP_CONTENT_PROTECTION:
286             if (cap_len < 2){
287                 log_info("    ERROR: REJECT CATEGORY, BAD_CP_FORMAT\n");
288                 connection->reject_service_category = category;
289                 connection->error_code = BAD_CP_FORMAT;
290                 return 1;
291             }
292             break;
293         case AVDTP_HEADER_COMPRESSION:
294             // TODO: find error code for bad header compression
295             if (cap_len != 1){
296                 log_info("    ERROR: REJECT CATEGORY, BAD_HEADER_COMPRESSION\n");
297                 connection->reject_service_category = category;
298                 connection->error_code = BAD_RECOVERY_FORMAT;
299                 return 1;
300             }
301             break;
302         case AVDTP_MULTIPLEXING:
303             break;
304         case AVDTP_MEDIA_CODEC:
305             break;
306         default:
307             break;
308     }
309     return 0;
310 }
311 
312 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){
313 
314     int i;
315 
316     uint16_t registered_service_categories = 0;
317     uint16_t to_process = size;
318 
319     while (to_process >= 2){
320 
321         avdtp_service_category_t category = (avdtp_service_category_t) packet[0];
322         uint8_t cap_len = packet[1];
323         packet     += 2;
324         to_process -= 2;
325 
326         if (cap_len > to_process){
327             connection->reject_service_category = category;
328             connection->error_code = BAD_LENGTH;
329             return 0;
330         }
331 
332         if (avdtp_unpack_service_capabilities_has_errors(connection, signal_identifier, category, cap_len)) return 0;
333 
334         int category_valid = 1;
335 
336         uint8_t * data = packet;
337         uint16_t  pos = 0;
338 
339         switch(category){
340             case AVDTP_RECOVERY:
341                 caps->recovery.recovery_type = data[pos++];
342                 caps->recovery.maximum_recovery_window_size = data[pos++];
343                 caps->recovery.maximum_number_media_packets = data[pos++];
344                 break;
345             case AVDTP_CONTENT_PROTECTION:
346                 caps->content_protection.cp_type = big_endian_read_16(data, 0);
347                 caps->content_protection.cp_type_value_len = cap_len - 2;
348                 // connection->reject_service_category = category;
349                 // connection->error_code = UNSUPPORTED_CONFIGURATION;
350                 // support for content protection goes here
351                 break;
352             case AVDTP_HEADER_COMPRESSION:
353                 caps->header_compression.back_ch  = (data[0] >> 7) & 1;
354                 caps->header_compression.media    = (data[0] >> 6) & 1;
355                 caps->header_compression.recovery = (data[0] >> 5) & 1;
356                 break;
357             case AVDTP_MULTIPLEXING:
358                 caps->multiplexing_mode.fragmentation = (data[pos++] >> 7) & 1;
359                 // read [tsid, tcid] for media, reporting. recovery respectively
360                 caps->multiplexing_mode.transport_identifiers_num = 3;
361                 for (i=0; i<caps->multiplexing_mode.transport_identifiers_num; i++){
362                     caps->multiplexing_mode.transport_session_identifiers[i] = (data[pos++] >> 7) & 1;
363                     caps->multiplexing_mode.tcid[i] = (data[pos++] >> 7) & 1;
364                 }
365                 break;
366             case AVDTP_MEDIA_CODEC:
367                 caps->media_codec.media_type = (avdtp_media_type_t)(data[pos++] >> 4);
368                 caps->media_codec.media_codec_type = (avdtp_media_codec_type_t)(data[pos++]);
369                 caps->media_codec.media_codec_information_len = cap_len - 2;
370                 caps->media_codec.media_codec_information = &data[pos++];
371                 break;
372             case AVDTP_MEDIA_TRANSPORT:
373             case AVDTP_REPORTING:
374             case AVDTP_DELAY_REPORTING:
375                 break;
376             default:
377                 category_valid = 0;
378                 break;
379         }
380 
381         if (category_valid) {
382             registered_service_categories = store_bit16(registered_service_categories, category, 1);
383         }
384 
385         packet     += cap_len;
386         to_process -= cap_len;
387     }
388 
389     return registered_service_categories;
390 }
391 
392 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){
393     if (signaling_packet->offset) return;
394     bool basic_capabilities_only = false;
395     signaling_packet->message_type = AVDTP_RESPONSE_ACCEPT_MSG;
396     int i;
397 
398     signaling_packet->size = 0;
399     memset(signaling_packet->command, 0 , sizeof(signaling_packet->command));
400 
401     switch (identifier) {
402         case AVDTP_SI_GET_CAPABILITIES:
403             basic_capabilities_only = true;
404             break;
405         case AVDTP_SI_GET_ALL_CAPABILITIES:
406             break;
407         case AVDTP_SI_SET_CONFIGURATION:
408             signaling_packet->command[signaling_packet->size++] = signaling_packet->acp_seid << 2;
409             signaling_packet->command[signaling_packet->size++] = signaling_packet->int_seid << 2;
410             signaling_packet->message_type = AVDTP_CMD_MSG;
411             break;
412         case AVDTP_SI_RECONFIGURE:
413             signaling_packet->command[signaling_packet->size++] = signaling_packet->acp_seid << 2;
414             signaling_packet->message_type = AVDTP_CMD_MSG;
415             break;
416         default:
417             log_error("avdtp_prepare_capabilities wrong identifier %d", identifier);
418             break;
419     }
420 
421     for (i = AVDTP_MEDIA_TRANSPORT; i <= AVDTP_DELAY_REPORTING; i++){
422         int registered_category = get_bit16(service_categories, i);
423         if (!registered_category && (identifier == AVDTP_SI_SET_CONFIGURATION)){
424             // TODO: introduce bitmap of mandatory categories
425             if (i == AVDTP_MEDIA_TRANSPORT){
426                 registered_category = true;
427             }
428         }
429         // AVDTP_SI_GET_CAPABILITIES reports only basic capabilities (i.e., it skips non-basic categories)
430         if (basic_capabilities_only && !avdtp_is_basic_capability(i)){
431             registered_category = false;
432         }
433 
434         if (registered_category){
435             // service category
436             signaling_packet->command[signaling_packet->size++] = i;
437             signaling_packet->size += avdtp_pack_service_capabilities(signaling_packet->command + signaling_packet->size,
438                     sizeof(signaling_packet->command) - signaling_packet->size, capabilities, (avdtp_service_category_t) i);
439         }
440     }
441     signaling_packet->signal_identifier = (avdtp_signal_identifier_t)identifier;
442     signaling_packet->transaction_label = transaction_label;
443 }
444 
445 int avdtp_signaling_create_fragment(uint16_t cid, avdtp_signaling_packet_t * signaling_packet, uint8_t * out_buffer) {
446     int mtu = l2cap_get_remote_mtu_for_local_cid(cid);
447     int data_len = 0;
448 
449     uint16_t offset = signaling_packet->offset;
450     uint16_t pos = 1;
451 
452     if (offset == 0){
453         if (signaling_packet->size <= (mtu - 2)){
454             signaling_packet->packet_type = AVDTP_SINGLE_PACKET;
455             out_buffer[pos++] = signaling_packet->signal_identifier;
456             data_len = signaling_packet->size;
457         } else {
458             signaling_packet->packet_type = AVDTP_START_PACKET;
459             out_buffer[pos++] = (mtu + signaling_packet->size)/ (mtu-1);
460             out_buffer[pos++] = signaling_packet->signal_identifier;
461             data_len = mtu - 3;
462             signaling_packet->offset = data_len;
463         }
464     } else {
465         int remaining_bytes = signaling_packet->size - offset;
466         if (remaining_bytes <= (mtu - 1)){
467             signaling_packet->packet_type = AVDTP_END_PACKET;
468             data_len = remaining_bytes;
469             signaling_packet->offset = 0;
470         } else{
471             signaling_packet->packet_type = AVDTP_CONTINUE_PACKET;
472             data_len = mtu - 1;
473             signaling_packet->offset += data_len;
474         }
475     }
476     out_buffer[0] = avdtp_header(signaling_packet->transaction_label, signaling_packet->packet_type, signaling_packet->message_type);
477     (void)memcpy(out_buffer + pos, signaling_packet->command + offset,
478                  data_len);
479     pos += data_len;
480     return pos;
481 }
482 
483 
484 void avdtp_signaling_emit_connection_established(uint16_t avdtp_cid, bd_addr_t addr, uint8_t status) {
485     uint8_t event[12];
486     int pos = 0;
487     event[pos++] = HCI_EVENT_AVDTP_META;
488     event[pos++] = sizeof(event) - 2;
489     event[pos++] = AVDTP_SUBEVENT_SIGNALING_CONNECTION_ESTABLISHED;
490     little_endian_store_16(event, pos, avdtp_cid);
491     pos += 2;
492     reverse_bd_addr(addr,&event[pos]);
493     pos += 6;
494     event[pos++] = status;
495     avdtp_emit_sink_and_source(event, pos);
496 }
497 
498 void avdtp_signaling_emit_connection_released(uint16_t avdtp_cid) {
499     uint8_t event[5];
500     int pos = 0;
501     event[pos++] = HCI_EVENT_AVDTP_META;
502     event[pos++] = sizeof(event) - 2;
503     event[pos++] = AVDTP_SUBEVENT_SIGNALING_CONNECTION_RELEASED;
504     little_endian_store_16(event, pos, avdtp_cid);
505     pos += 2;
506     avdtp_emit_sink_and_source(event, pos);
507 }
508 
509 void avdtp_signaling_emit_sep(uint16_t avdtp_cid, avdtp_sep_t sep) {
510     uint8_t event[9];
511     int pos = 0;
512     event[pos++] = HCI_EVENT_AVDTP_META;
513     event[pos++] = sizeof(event) - 2;
514     event[pos++] = AVDTP_SUBEVENT_SIGNALING_SEP_FOUND;
515     little_endian_store_16(event, pos, avdtp_cid);
516     pos += 2;
517     event[pos++] = sep.seid;
518     event[pos++] = sep.in_use;
519     event[pos++] = sep.media_type;
520     event[pos++] = sep.type;
521     avdtp_emit_sink_and_source(event, pos);
522 }
523 
524 void avdtp_signaling_emit_sep_done(uint16_t avdtp_cid) {
525     uint8_t event[5];
526     int pos = 0;
527     event[pos++] = HCI_EVENT_AVDTP_META;
528     event[pos++] = sizeof(event) - 2;
529     event[pos++] = AVDTP_SUBEVENT_SIGNALING_SEP_DICOVERY_DONE;
530     little_endian_store_16(event, pos, avdtp_cid);
531     pos += 2;
532     avdtp_emit_sink_and_source(event, pos);
533 }
534 
535 void avdtp_signaling_emit_accept(uint16_t avdtp_cid, uint8_t local_seid, avdtp_signal_identifier_t identifier, bool is_initiator) {
536     uint8_t event[8];
537     int pos = 0;
538     event[pos++] = HCI_EVENT_AVDTP_META;
539     event[pos++] = sizeof(event) - 2;
540     event[pos++] = AVDTP_SUBEVENT_SIGNALING_ACCEPT;
541     little_endian_store_16(event, pos, avdtp_cid);
542     pos += 2;
543     event[pos++] = local_seid;
544     event[pos++] = is_initiator ? 1 : 0;
545     event[pos++] = identifier;
546     avdtp_emit_sink_and_source(event, pos);
547 }
548 
549 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){
550     uint8_t event[8];
551     int pos = 0;
552     event[pos++] = HCI_EVENT_AVDTP_META;
553     event[pos++] = sizeof(event) - 2;
554     event[pos++] = AVDTP_SUBEVENT_SIGNALING_ACCEPT;
555     little_endian_store_16(event, pos, stream_endpoint->connection->avdtp_cid);
556     pos += 2;
557     event[pos++] = local_seid;
558     event[pos++] = is_initiator ? 1 : 0;
559     event[pos++] = identifier;
560 
561     btstack_packet_handler_t packet_handler = avdtp_packet_handler_for_stream_endpoint(stream_endpoint);
562     (*packet_handler)(HCI_EVENT_PACKET, 0, event, pos);
563 }
564 
565 void avdtp_signaling_emit_reject(uint16_t avdtp_cid, uint8_t local_seid, avdtp_signal_identifier_t identifier, bool is_initiator) {
566     uint8_t event[8];
567     int pos = 0;
568     event[pos++] = HCI_EVENT_AVDTP_META;
569     event[pos++] = sizeof(event) - 2;
570     event[pos++] = AVDTP_SUBEVENT_SIGNALING_REJECT;
571     little_endian_store_16(event, pos, avdtp_cid);
572     pos += 2;
573     event[pos++] = local_seid;
574     event[pos++] = is_initiator ? 1 : 0;
575     event[pos++] = identifier;
576     avdtp_emit_sink_and_source(event, pos);
577 }
578 
579 void avdtp_signaling_emit_general_reject(uint16_t avdtp_cid, uint8_t local_seid, avdtp_signal_identifier_t identifier, bool is_initiator) {
580     uint8_t event[8];
581     int pos = 0;
582     event[pos++] = HCI_EVENT_AVDTP_META;
583     event[pos++] = sizeof(event) - 2;
584     event[pos++] = AVDTP_SUBEVENT_SIGNALING_GENERAL_REJECT;
585     little_endian_store_16(event, pos, avdtp_cid);
586     pos += 2;
587     event[pos++] = local_seid;
588     event[pos++] = is_initiator ? 1 : 0;
589     event[pos++] = identifier;
590     avdtp_emit_sink_and_source(event, pos);
591 }
592 
593 static inline void
594 avdtp_signaling_emit_capability(uint8_t capability_subevent_id, uint16_t avdtp_cid, uint8_t local_seid, uint8_t remote_seid) {
595     uint8_t event[7];
596     int pos = 0;
597     event[pos++] = HCI_EVENT_AVDTP_META;
598     event[pos++] = sizeof(event) - 2;
599     event[pos++] = capability_subevent_id;
600     little_endian_store_16(event, pos, avdtp_cid);
601     pos += 2;
602     event[pos++] = local_seid;
603     event[pos++] = remote_seid;
604     avdtp_emit_sink_and_source(event, pos);
605 }
606 
607 static void avdtp_signaling_emit_media_codec_sbc_capability(uint16_t avdtp_cid, uint8_t local_seid, uint8_t remote_seid,
608                                                             adtvp_media_codec_capabilities_t media_codec) {
609     uint8_t event[15];
610     int pos = 0;
611     event[pos++] = HCI_EVENT_AVDTP_META;
612     event[pos++] = sizeof(event) - 2;
613     event[pos++] = AVDTP_SUBEVENT_SIGNALING_MEDIA_CODEC_SBC_CAPABILITY;
614     little_endian_store_16(event, pos, avdtp_cid);
615     pos += 2;
616     event[pos++] = local_seid;
617     event[pos++] = remote_seid;
618     event[pos++] = media_codec.media_type;
619     event[pos++] = media_codec.media_codec_information[0] >> 4;
620     event[pos++] = media_codec.media_codec_information[0] & 0x0F;
621     event[pos++] = media_codec.media_codec_information[1] >> 4;
622     event[pos++] = (media_codec.media_codec_information[1] & 0x0F) >> 2;
623     event[pos++] = media_codec.media_codec_information[1] & 0x03;
624     event[pos++] = media_codec.media_codec_information[2];
625     event[pos++] = media_codec.media_codec_information[3];
626     avdtp_emit_sink_and_source(event, pos);
627 }
628 
629 static void avdtp_signaling_emit_media_codec_other_capability(uint16_t avdtp_cid, uint8_t local_seid, uint8_t remote_seid,
630                                                   adtvp_media_codec_capabilities_t media_codec) {
631     uint8_t event[MAX_MEDIA_CODEC_INFORMATION_LENGTH + 12];
632     int pos = 0;
633     event[pos++] = HCI_EVENT_AVDTP_META;
634     event[pos++] = sizeof(event) - 2;
635     event[pos++] = AVDTP_SUBEVENT_SIGNALING_MEDIA_CODEC_OTHER_CAPABILITY;
636     little_endian_store_16(event, pos, avdtp_cid);
637     pos += 2;
638     event[pos++] = local_seid;
639     event[pos++] = remote_seid;
640     event[pos++] = media_codec.media_type;
641     little_endian_store_16(event, pos, media_codec.media_codec_type);
642     pos += 2;
643     little_endian_store_16(event, pos, media_codec.media_codec_information_len);
644     pos += 2;
645     (void)memcpy(event + pos, media_codec.media_codec_information,
646                  btstack_min(media_codec.media_codec_information_len, MAX_MEDIA_CODEC_INFORMATION_LENGTH));
647     avdtp_emit_sink_and_source(event, pos);
648 }
649 
650 static void
651 avdtp_signaling_emit_media_transport_capability(uint16_t avdtp_cid, uint8_t local_seid, uint8_t remote_seid) {
652     avdtp_signaling_emit_capability(AVDTP_SUBEVENT_SIGNALING_MEDIA_TRANSPORT_CAPABILITY, avdtp_cid, local_seid,
653                                     remote_seid);
654 }
655 
656 static void avdtp_signaling_emit_reporting_capability(uint16_t avdtp_cid, uint8_t local_seid, uint8_t remote_seid) {
657     avdtp_signaling_emit_capability(AVDTP_SUBEVENT_SIGNALING_REPORTING_CAPABILITY, avdtp_cid, local_seid, remote_seid);
658 }
659 
660 static void
661 avdtp_signaling_emit_delay_reporting_capability(uint16_t avdtp_cid, uint8_t local_seid, uint8_t remote_seid) {
662     avdtp_signaling_emit_capability(AVDTP_SUBEVENT_SIGNALING_DELAY_REPORTING_CAPABILITY, avdtp_cid, local_seid,
663                                     remote_seid);
664 }
665 
666 static void avdtp_signaling_emit_recovery_capability(uint16_t avdtp_cid, uint8_t local_seid, uint8_t remote_seid,
667                                                      avdtp_recovery_capabilities_t *recovery) {
668     uint8_t event[10];
669     int pos = 0;
670     event[pos++] = HCI_EVENT_AVDTP_META;
671     event[pos++] = sizeof(event) - 2;
672     event[pos++] = AVDTP_SUBEVENT_SIGNALING_RECOVERY_CAPABILITY;
673     little_endian_store_16(event, pos, avdtp_cid);
674     pos += 2;
675     event[pos++] = local_seid;
676     event[pos++] = remote_seid;
677     event[pos++] = recovery->recovery_type;
678     event[pos++] = recovery->maximum_recovery_window_size;
679     event[pos++] = recovery->maximum_number_media_packets;
680     avdtp_emit_sink_and_source(event, pos);
681 }
682 
683 static void
684 avdtp_signaling_emit_content_protection_capability(uint16_t avdtp_cid, uint8_t local_seid, uint8_t remote_seid,
685                                                    adtvp_content_protection_t *content_protection) {
686     uint8_t event[22];
687     int pos = 0;
688     event[pos++] = HCI_EVENT_AVDTP_META;
689     event[pos++] = sizeof(event) - 2;
690     event[pos++] = AVDTP_SUBEVENT_SIGNALING_CONTENT_PROTECTION_CAPABILITY;
691     little_endian_store_16(event, pos, avdtp_cid);
692     pos += 2;
693     event[pos++] = local_seid;
694     event[pos++] = remote_seid;
695 
696     little_endian_store_16(event, pos, content_protection->cp_type);
697     pos += 2;
698     little_endian_store_16(event, pos, content_protection->cp_type_value_len);
699     pos += 2;
700 
701     //TODO: reserve place for value
702     if (content_protection->cp_type_value_len < 10){
703         (void)memcpy(event + pos, content_protection->cp_type_value,
704                      content_protection->cp_type_value_len);
705     }
706     avdtp_emit_sink_and_source(event, pos);
707 }
708 
709 
710 static void
711 avdtp_signaling_emit_header_compression_capability(uint16_t avdtp_cid, uint8_t local_seid, uint8_t remote_seid,
712                                                    avdtp_header_compression_capabilities_t *header_compression) {
713     uint8_t event[10];
714     int pos = 0;
715     event[pos++] = HCI_EVENT_AVDTP_META;
716     event[pos++] = sizeof(event) - 2;
717     event[pos++] = AVDTP_SUBEVENT_SIGNALING_HEADER_COMPRESSION_CAPABILITY;
718     little_endian_store_16(event, pos, avdtp_cid);
719     pos += 2;
720     event[pos++] = local_seid;
721     event[pos++] = remote_seid;
722     event[pos++] = header_compression->back_ch;
723     event[pos++] = header_compression->media;
724     event[pos++] = header_compression->recovery;
725     avdtp_emit_sink_and_source(event, pos);
726 }
727 
728 static void
729 avdtp_signaling_emit_content_multiplexing_capability(uint16_t avdtp_cid, uint8_t local_seid, uint8_t remote_seid,
730                                                      avdtp_multiplexing_mode_capabilities_t *multiplexing_mode) {
731     uint8_t event[15];
732     int pos = 0;
733     event[pos++] = HCI_EVENT_AVDTP_META;
734     event[pos++] = sizeof(event) - 2;
735     event[pos++] = AVDTP_SUBEVENT_SIGNALING_MULTIPLEXING_CAPABILITY;
736     little_endian_store_16(event, pos, avdtp_cid);
737     pos += 2;
738     event[pos++] = local_seid;
739     event[pos++] = remote_seid;
740 
741     event[pos++] = multiplexing_mode->fragmentation;
742     event[pos++] = multiplexing_mode->transport_identifiers_num;
743 
744     int i;
745     for (i = 0; i < 3; i++){
746         event[pos++] = multiplexing_mode->transport_session_identifiers[i];
747     }
748     for (i = 0; i < 3; i++){
749         event[pos++] = multiplexing_mode->tcid[i];
750     }
751     avdtp_emit_sink_and_source(event, pos);
752 }
753 
754 static void avdtp_signaling_emit_capability_done(uint16_t avdtp_cid, uint8_t local_seid, uint8_t remote_seid) {
755     uint8_t event[7];
756     int pos = 0;
757     event[pos++] = HCI_EVENT_AVDTP_META;
758     event[pos++] = sizeof(event) - 2;
759     event[pos++] = AVDTP_SUBEVENT_SIGNALING_CAPABILITIES_DONE;
760     little_endian_store_16(event, pos, avdtp_cid);
761     pos += 2;
762     event[pos++] = local_seid;
763     event[pos++] = remote_seid;
764     avdtp_emit_sink_and_source(event, pos);
765 }
766 
767 // emit events for all capabilities incl. final done event
768 void avdtp_signaling_emit_capabilities(uint16_t avdtp_cid, uint8_t local_seid, uint8_t remote_seid, avdtp_capabilities_t *capabilities,
769                                        uint16_t registered_service_categories) {
770     if (get_bit16(registered_service_categories, AVDTP_MEDIA_CODEC)){
771         switch (capabilities->media_codec.media_codec_type){
772             case AVDTP_CODEC_SBC:
773                 avdtp_signaling_emit_media_codec_sbc_capability(avdtp_cid, local_seid, remote_seid, capabilities->media_codec);
774                 break;
775             default:
776                 avdtp_signaling_emit_media_codec_other_capability(avdtp_cid, local_seid, remote_seid, capabilities->media_codec);
777                 break;
778         }
779     }
780 
781     if (get_bit16(registered_service_categories, AVDTP_MEDIA_TRANSPORT)){
782         avdtp_signaling_emit_media_transport_capability(avdtp_cid, local_seid, remote_seid);
783     }
784     if (get_bit16(registered_service_categories, AVDTP_REPORTING)){
785         avdtp_signaling_emit_reporting_capability(avdtp_cid, local_seid, remote_seid);
786     }
787     if (get_bit16(registered_service_categories, AVDTP_RECOVERY)){
788         avdtp_signaling_emit_recovery_capability(avdtp_cid, local_seid, remote_seid, &capabilities->recovery);
789     }
790     if (get_bit16(registered_service_categories, AVDTP_CONTENT_PROTECTION)){
791         avdtp_signaling_emit_content_protection_capability(avdtp_cid, local_seid, remote_seid,
792                                                            &capabilities->content_protection);
793     }
794     if (get_bit16(registered_service_categories, AVDTP_HEADER_COMPRESSION)){
795         avdtp_signaling_emit_header_compression_capability(avdtp_cid, local_seid, remote_seid,
796                                                            &capabilities->header_compression);
797     }
798     if (get_bit16(registered_service_categories, AVDTP_MULTIPLEXING)){
799         avdtp_signaling_emit_content_multiplexing_capability(avdtp_cid, local_seid, remote_seid,
800                                                              &capabilities->multiplexing_mode);
801     }
802     if (get_bit16(registered_service_categories, AVDTP_DELAY_REPORTING)){
803         avdtp_signaling_emit_delay_reporting_capability(avdtp_cid, local_seid, remote_seid);
804     }
805     avdtp_signaling_emit_capability_done(avdtp_cid, local_seid, remote_seid);
806 }
807 
808 static void avdtp_signaling_emit_media_codec_sbc(avdtp_stream_endpoint_t *stream_endpoint, uint16_t avdtp_cid,
809                                      avdtp_media_type_t media_type, const uint8_t *media_codec_information,
810                                      uint8_t reconfigure) {
811 
812     btstack_packet_handler_t packet_handler = avdtp_packet_handler_for_stream_endpoint(stream_endpoint);
813     uint8_t local_seid = avdtp_local_seid(stream_endpoint);
814     uint8_t remote_seid = avdtp_remote_seid(stream_endpoint);
815 
816     uint8_t event[16 + 2];
817     int pos = 0;
818     event[pos++] = HCI_EVENT_AVDTP_META;
819     event[pos++] = sizeof(event) - 2;
820 
821     event[pos++] = AVDTP_SUBEVENT_SIGNALING_MEDIA_CODEC_SBC_CONFIGURATION;
822     little_endian_store_16(event, pos, avdtp_cid);
823     pos += 2;
824     event[pos++] = local_seid;
825     event[pos++] = remote_seid;
826     event[pos++] = reconfigure;
827 
828 
829     uint8_t sampling_frequency_bitmap = media_codec_information[0] >> 4;
830     uint8_t channel_mode_bitmap = media_codec_information[0] & 0x0F;
831     uint8_t block_length_bitmap = media_codec_information[1] >> 4;
832     uint8_t subbands_bitmap = (media_codec_information[1] & 0x0F) >> 2;
833 
834     uint8_t num_channels = 0;
835     if ((channel_mode_bitmap & AVDTP_SBC_JOINT_STEREO) ||
836         (channel_mode_bitmap & AVDTP_SBC_STEREO) ||
837         (channel_mode_bitmap & AVDTP_SBC_DUAL_CHANNEL)) {
838         num_channels = 2;
839     } else if (channel_mode_bitmap & AVDTP_SBC_MONO) {
840         num_channels = 1;
841     }
842 
843     uint16_t sampling_frequency = 0;
844     if (sampling_frequency_bitmap & AVDTP_SBC_48000) {
845         sampling_frequency = 48000;
846     } else if (sampling_frequency_bitmap & AVDTP_SBC_44100) {
847         sampling_frequency = 44100;
848     } else if (sampling_frequency_bitmap & AVDTP_SBC_32000) {
849         sampling_frequency = 32000;
850     } else if (sampling_frequency_bitmap & AVDTP_SBC_16000) {
851         sampling_frequency = 16000;
852     }
853 
854     uint8_t subbands = 0;
855     if (subbands_bitmap & AVDTP_SBC_SUBBANDS_8){
856         subbands = 8;
857     } else if (subbands_bitmap & AVDTP_SBC_SUBBANDS_4){
858         subbands = 4;
859     }
860 
861     uint8_t block_length = 0;
862     if (block_length_bitmap & AVDTP_SBC_BLOCK_LENGTH_16){
863         block_length = 16;
864     } else if (block_length_bitmap & AVDTP_SBC_BLOCK_LENGTH_12){
865         block_length = 12;
866     } else if (block_length_bitmap & AVDTP_SBC_BLOCK_LENGTH_8){
867         block_length = 8;
868     } else if (block_length_bitmap & AVDTP_SBC_BLOCK_LENGTH_4){
869         block_length = 4;
870     }
871 
872     event[pos++] = media_type;
873     little_endian_store_16(event, pos, sampling_frequency);
874     pos += 2;
875 
876     event[pos++] = channel_mode_bitmap;
877     event[pos++] = num_channels;
878     event[pos++] = block_length;
879     event[pos++] = subbands;
880     event[pos++] = media_codec_information[1] & 0x03;
881     event[pos++] = media_codec_information[2];
882     event[pos++] = media_codec_information[3];
883     (*packet_handler)(HCI_EVENT_PACKET, 0, event, sizeof(event));
884 }
885 
886 static void avdtp_signaling_emit_media_codec_other(avdtp_stream_endpoint_t *stream_endpoint, uint16_t avdtp_cid,
887                                        adtvp_media_codec_capabilities_t * media_codec, uint8_t reconfigure) {
888 
889     btstack_packet_handler_t packet_handler = avdtp_packet_handler_for_stream_endpoint(stream_endpoint);
890     uint8_t local_seid = avdtp_local_seid(stream_endpoint);
891     uint8_t remote_seid = avdtp_remote_seid(stream_endpoint);
892 
893     uint8_t event[MAX_MEDIA_CODEC_INFORMATION_LENGTH + 13];
894     int pos = 0;
895     event[pos++] = HCI_EVENT_AVDTP_META;
896     event[pos++] = sizeof(event) - 2;
897     event[pos++] = AVDTP_SUBEVENT_SIGNALING_MEDIA_CODEC_OTHER_CONFIGURATION;
898     little_endian_store_16(event, pos, avdtp_cid);
899     pos += 2;
900     event[pos++] = local_seid;
901     event[pos++] = remote_seid;
902     event[pos++] = reconfigure;
903     event[pos++] = media_codec->media_type;
904     little_endian_store_16(event, pos, media_codec->media_codec_type);
905     pos += 2;
906     little_endian_store_16(event, pos, media_codec->media_codec_information_len);
907     pos += 2;
908 
909     int media_codec_len = btstack_min(MAX_MEDIA_CODEC_INFORMATION_LENGTH, media_codec->media_codec_information_len);
910     (void)memcpy(event + pos, media_codec->media_codec_information, media_codec_len);
911 
912     (*packet_handler)(HCI_EVENT_PACKET, 0, event, sizeof(event));
913 }
914 
915 void avdtp_signaling_emit_delay(uint16_t avdtp_cid, uint8_t local_seid, uint16_t delay) {
916     uint8_t event[8];
917     int pos = 0;
918     event[pos++] = HCI_EVENT_AVDTP_META;
919     event[pos++] = sizeof(event) - 2;
920     event[pos++] = AVDTP_SUBEVENT_SIGNALING_DELAY_REPORT;
921     little_endian_store_16(event, pos, avdtp_cid);
922     pos += 2;
923     event[pos++] = local_seid;
924     little_endian_store_16(event, pos, delay);
925     pos += 2;
926     avdtp_emit_source(event, sizeof(event));
927 }
928 
929 void avdtp_signaling_emit_media_codec_sbc_configuration(avdtp_stream_endpoint_t *stream_endpoint, uint16_t avdtp_cid,
930                                                         avdtp_media_type_t media_type,
931                                                         const uint8_t *media_codec_information) {
932     avdtp_signaling_emit_media_codec_sbc(stream_endpoint, avdtp_cid, media_type,
933                                          media_codec_information, 0);
934 }
935 
936 void avdtp_signaling_emit_media_codec_other_configuration(avdtp_stream_endpoint_t *stream_endpoint, uint16_t avdtp_cid,
937                                                           adtvp_media_codec_capabilities_t * media_codec) {
938     avdtp_signaling_emit_media_codec_other(stream_endpoint, avdtp_cid, media_codec, 0);
939 }
940 
941 void avdtp_signaling_emit_configuration(avdtp_stream_endpoint_t *stream_endpoint, uint16_t avdtp_cid,
942                                         avdtp_capabilities_t *configuration, uint16_t configured_service_categories) {
943 
944     if (get_bit16(configured_service_categories, AVDTP_MEDIA_CODEC)){
945         switch (configuration->media_codec.media_codec_type){
946             case AVDTP_CODEC_SBC:
947                 avdtp_signaling_emit_media_codec_sbc_configuration(
948                         stream_endpoint, avdtp_cid,
949                         configuration->media_codec.media_type,
950                         configuration->media_codec.media_codec_information);
951                 break;
952             default:
953                 avdtp_signaling_emit_media_codec_other_configuration(stream_endpoint, avdtp_cid,
954                                                                      &configuration->media_codec);
955                 break;
956         }
957     }
958 }
959 
960 void avdtp_streaming_emit_connection_established(avdtp_stream_endpoint_t *stream_endpoint, uint8_t status) {
961     uint8_t event[14];
962     int pos = 0;
963     event[pos++] = HCI_EVENT_AVDTP_META;
964     event[pos++] = sizeof(event) - 2;
965     event[pos++] = AVDTP_SUBEVENT_STREAMING_CONNECTION_ESTABLISHED;
966     little_endian_store_16(event, pos, stream_endpoint->connection->avdtp_cid);
967     pos += 2;
968     reverse_bd_addr(stream_endpoint->connection->remote_addr, &event[pos]);
969     pos += 6;
970     event[pos++] = avdtp_local_seid(stream_endpoint);
971     event[pos++] = avdtp_remote_seid(stream_endpoint);
972     event[pos++] = status;
973 
974     btstack_packet_handler_t packet_handler = avdtp_packet_handler_for_stream_endpoint(stream_endpoint);
975     (*packet_handler)(HCI_EVENT_PACKET, 0, event, sizeof(event));
976 }
977 
978 void avdtp_streaming_emit_connection_released(avdtp_stream_endpoint_t *stream_endpoint, uint16_t avdtp_cid, uint8_t local_seid) {
979     uint8_t event[6];
980     int pos = 0;
981     event[pos++] = HCI_EVENT_AVDTP_META;
982     event[pos++] = sizeof(event) - 2;
983     event[pos++] = AVDTP_SUBEVENT_STREAMING_CONNECTION_RELEASED;
984     little_endian_store_16(event, pos, avdtp_cid);
985     pos += 2;
986     event[pos++] = local_seid;
987 
988     btstack_packet_handler_t packet_handler = avdtp_packet_handler_for_stream_endpoint(stream_endpoint);
989     (*packet_handler)(HCI_EVENT_PACKET, 0, event, sizeof(event));
990 }
991 
992 void avdtp_streaming_emit_can_send_media_packet_now(avdtp_stream_endpoint_t *stream_endpoint, uint16_t sequence_number) {
993     uint8_t event[8];
994     int pos = 0;
995     event[pos++] = HCI_EVENT_AVDTP_META;
996     event[pos++] = sizeof(event) - 2;
997     event[pos++] = AVDTP_SUBEVENT_STREAMING_CAN_SEND_MEDIA_PACKET_NOW;
998     little_endian_store_16(event, pos, stream_endpoint->connection->avdtp_cid);
999     pos += 2;
1000     event[pos++] = avdtp_local_seid(stream_endpoint);
1001     little_endian_store_16(event, pos, sequence_number);
1002     pos += 2;
1003 
1004     btstack_packet_handler_t packet_handler = avdtp_packet_handler_for_stream_endpoint(stream_endpoint);
1005     (*packet_handler)(HCI_EVENT_PACKET, 0, event, sizeof(event));
1006 }
1007 
1008 uint8_t avdtp_request_can_send_now_acceptor(avdtp_connection_t * connection, uint16_t l2cap_cid){
1009     if (!connection) return ERROR_CODE_UNKNOWN_CONNECTION_IDENTIFIER;
1010     connection->wait_to_send_acceptor = 1;
1011     l2cap_request_can_send_now_event(l2cap_cid);
1012     return ERROR_CODE_SUCCESS;
1013 }
1014 
1015 uint8_t avdtp_request_can_send_now_initiator(avdtp_connection_t * connection, uint16_t l2cap_cid){
1016     if (!connection) return ERROR_CODE_UNKNOWN_CONNECTION_IDENTIFIER;
1017     connection->wait_to_send_initiator = 1;
1018     l2cap_request_can_send_now_event(l2cap_cid);
1019     return ERROR_CODE_SUCCESS;
1020 }
1021 
1022 uint8_t avdtp_local_seid(avdtp_stream_endpoint_t * stream_endpoint){
1023     if (!stream_endpoint) return 0;
1024     return stream_endpoint->sep.seid;
1025 
1026 }
1027 
1028 uint8_t avdtp_remote_seid(avdtp_stream_endpoint_t * stream_endpoint){
1029     if (!stream_endpoint) return AVDTP_INVALID_SEP_SEID;
1030     return stream_endpoint->remote_sep.seid;
1031 }
1032 
1033 // helper for A2DP
1034 
1035 void a2dp_replace_subevent_id_and_emit_cmd(btstack_packet_handler_t callback, uint8_t * packet, uint16_t size, uint8_t subevent_id){
1036     UNUSED(size);
1037     btstack_assert(callback != NULL);
1038     packet[0] = HCI_EVENT_A2DP_META;
1039     packet[2] = subevent_id;
1040     (*callback)(HCI_EVENT_PACKET, 0, packet, size);
1041 }
1042 
1043 void a2dp_emit_streaming_connection_established(btstack_packet_handler_t callback, uint8_t * packet, uint16_t size, uint8_t status){
1044     btstack_assert(callback != NULL);
1045     packet[0] = HCI_EVENT_A2DP_META;
1046     packet[2] = A2DP_SUBEVENT_STREAM_ESTABLISHED;
1047     packet[12] = status;
1048     (*callback)(HCI_EVENT_PACKET, 0, packet, size);
1049 }
1050 
1051 void a2dp_emit_signaling_connection_established(btstack_packet_handler_t callback, uint8_t * packet, uint16_t size, uint8_t status){
1052     btstack_assert(callback != NULL);
1053     packet[0] = HCI_EVENT_A2DP_META;
1054     packet[2] = A2DP_SUBEVENT_SIGNALING_CONNECTION_ESTABLISHED;
1055     packet[10] = status;
1056     (*callback)(HCI_EVENT_PACKET, 0, packet, size);
1057 }
1058 
1059 void a2dp_emit_stream_event(btstack_packet_handler_t callback, uint16_t cid, uint8_t local_seid, uint8_t subevent_id){
1060     uint8_t event[6];
1061     int pos = 0;
1062     event[pos++] = HCI_EVENT_A2DP_META;
1063     event[pos++] = sizeof(event) - 2;
1064     event[pos++] = subevent_id;
1065     little_endian_store_16(event, pos, cid);
1066     pos += 2;
1067     event[pos++] = local_seid;
1068     (*callback)(HCI_EVENT_PACKET, 0, event, sizeof(event));
1069 }
1070