xref: /btstack/src/classic/avrcp_target.c (revision 7bccc69f5c5d0002997727d088e352af0c0d99a8)
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 BLUEKITCHEN
24  * GMBH 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__ "avrcp_target.c"
39 
40 #include <stdint.h>
41 #include <stdio.h>
42 #include <string.h>
43 #include <inttypes.h>
44 
45 #include "classic/avrcp.h"
46 #include "classic/avrcp_target.h"
47 
48 #include "bluetooth_sdp.h"
49 #include "btstack_debug.h"
50 #include "btstack_event.h"
51 #include "btstack_util.h"
52 #include "l2cap.h"
53 
54 #include <stdio.h>
55 #define AVRCP_ATTR_HEADER_LEN  8
56 
57 static const uint8_t AVRCP_NOTIFICATION_TRACK_SELECTED[] = {0,0,0,0,0,0,0,0};
58 static const uint8_t AVRCP_NOTIFICATION_TRACK_NOT_SELECTED[] = {0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF};
59 
60 avrcp_context_t avrcp_target_context;
61 
62 static uint32_t default_companies[] = {
63     0x581900 //BT SIG registered CompanyID
64 };
65 
66 static int avrcp_target_supports_browsing(uint16_t target_supported_features){
67     return target_supported_features & AVRCP_FEATURE_MASK_BROWSING;
68 }
69 
70 void avrcp_target_create_sdp_record(uint8_t * service, uint32_t service_record_handle, uint16_t supported_features, const char * service_name, const char * service_provider_name){
71     avrcp_create_sdp_record(0, service, service_record_handle, avrcp_target_supports_browsing(supported_features), supported_features, service_name, service_provider_name);
72 }
73 
74 static void
75 avrcp_target_emit_operation(btstack_packet_handler_t callback, uint16_t avrcp_cid, avrcp_operation_id_t operation_id,
76                             bool button_pressed, uint8_t operands_length, uint8_t operand) {
77     btstack_assert(callback != NULL);
78 
79     uint8_t event[9];
80     int pos = 0;
81     event[pos++] = HCI_EVENT_AVRCP_META;
82     event[pos++] = sizeof(event) - 2;
83     event[pos++] = AVRCP_SUBEVENT_OPERATION;
84     little_endian_store_16(event, pos, avrcp_cid);
85     pos += 2;
86     event[pos++] = operation_id;
87     event[pos++] = button_pressed ? 1 : 0;
88     event[pos++] = operands_length;
89     event[pos++] = operand;
90     (*callback)(HCI_EVENT_PACKET, 0, event, sizeof(event));
91 }
92 
93 static void avrcp_target_emit_volume_changed(btstack_packet_handler_t callback, uint16_t avrcp_cid, uint8_t absolute_volume){
94     btstack_assert(callback != NULL);
95 
96     uint8_t event[7];
97     int offset = 0;
98     event[offset++] = HCI_EVENT_AVRCP_META;
99     event[offset++] = sizeof(event) - 2;
100     event[offset++] = AVRCP_SUBEVENT_NOTIFICATION_VOLUME_CHANGED;
101     little_endian_store_16(event, offset, avrcp_cid);
102     offset += 2;
103     event[offset++] = AVRCP_CTYPE_NOTIFY;
104     event[offset++] = absolute_volume;
105     (*callback)(HCI_EVENT_PACKET, 0, event, sizeof(event));
106 }
107 
108 static void avrcp_target_emit_respond_vendor_dependent_query(btstack_packet_handler_t callback, uint16_t avrcp_cid, uint8_t subevent_id){
109     btstack_assert(callback != NULL);
110 
111     uint8_t event[5];
112     int pos = 0;
113     event[pos++] = HCI_EVENT_AVRCP_META;
114     event[pos++] = sizeof(event) - 2;
115     event[pos++] = subevent_id;
116     little_endian_store_16(event, pos, avrcp_cid);
117     (*callback)(HCI_EVENT_PACKET, 0, event, sizeof(event));
118 }
119 
120 // returns number of bytes stored
121 static uint16_t avrcp_target_pack_single_element_header(uint8_t * buffer, avrcp_media_attribute_id_t attr_id, uint16_t attr_value_size){
122     btstack_assert(attr_id > AVRCP_MEDIA_ATTR_ALL);
123     btstack_assert(attr_id < AVRCP_MEDIA_ATTR_RESERVED);
124     uint16_t pos = 0;
125     big_endian_store_32(buffer, pos, attr_id);
126     big_endian_store_16(buffer, pos + 4, RFC2978_CHARSET_MIB_UTF8);
127     big_endian_store_16(buffer, pos + 6, attr_value_size);
128     return 8;
129 }
130 
131 static uint16_t avrcp_now_playing_info_attr_id_value_len(avrcp_connection_t * connection, avrcp_media_attribute_id_t attr_id){
132     char buffer[AVRCP_MAX_ATTRIBUTE_SIZE];
133     uint16_t str_len;
134     switch (attr_id) {
135         case AVRCP_MEDIA_ATTR_ALL:
136         case AVRCP_MEDIA_ATTR_NONE:
137             return 0;
138         case AVRCP_MEDIA_ATTR_TRACK:
139             str_len = sprintf(buffer, "%0" PRIu32, connection->track_nr);
140             break;
141         case AVRCP_MEDIA_ATTR_TOTAL_NUM_ITEMS:
142             str_len = sprintf(buffer, "%0" PRIu32, connection->total_tracks);
143             break;
144         case AVRCP_MEDIA_ATTR_SONG_LENGTH_MS:
145             str_len = sprintf(buffer, "%0" PRIu32, connection->song_length_ms);
146             break;
147         default:
148             str_len = connection->now_playing_info[(uint16_t)attr_id - 1].len;
149             break;
150     }
151     return str_len;
152 }
153 
154 static uint16_t avrcp_now_playing_info_value_len_with_headers(avrcp_connection_t * connection){
155     uint16_t playing_info_len = 0;
156 
157     uint8_t i;
158     for ( i = (uint8_t)AVRCP_MEDIA_ATTR_ALL + 1; i < (uint8_t) AVRCP_MEDIA_ATTR_RESERVED; i++){
159         avrcp_media_attribute_id_t attr_id = (avrcp_media_attribute_id_t) i;
160 
161         if ((connection->now_playing_info_attr_bitmap & (1 << attr_id)) == 0) {
162             continue;
163         }
164 
165         switch (attr_id) {
166             case AVRCP_MEDIA_ATTR_ALL:
167             case AVRCP_MEDIA_ATTR_NONE:
168             case AVRCP_MEDIA_ATTR_DEFAULT_COVER_ART:
169                 break;
170             default:
171                 playing_info_len += AVRCP_ATTR_HEADER_LEN + avrcp_now_playing_info_attr_id_value_len(connection, attr_id);
172                 break;
173         }
174     }
175     // for total num bytes that of the attributes + headers
176     playing_info_len += 1;
177     return playing_info_len;
178 }
179 
180 static uint8_t * avrcp_get_attribute_value_from_u32(avrcp_connection_t * connection, uint32_t value, uint16_t * num_bytes_to_copy){
181     *num_bytes_to_copy = 0;
182 
183     if (connection->attribute_value_len == 0){
184         connection->attribute_value_len = sprintf((char *)connection->attribute_value, "%0" PRIu32, value);
185         connection->attribute_value_offset = 0;
186     }
187     *num_bytes_to_copy = connection->attribute_value_len - connection->attribute_value_offset;
188     return connection->attribute_value + connection->attribute_value_offset;
189 }
190 
191 static uint8_t * avrcp_get_next_value_fragment_for_attribute_id(avrcp_connection_t * connection, avrcp_media_attribute_id_t attr_id, uint16_t * num_bytes_to_copy){
192     switch (attr_id){
193         case AVRCP_MEDIA_ATTR_TRACK:
194             return avrcp_get_attribute_value_from_u32(connection, connection->track_nr, num_bytes_to_copy);
195         case AVRCP_MEDIA_ATTR_TOTAL_NUM_ITEMS:
196             return avrcp_get_attribute_value_from_u32(connection, connection->total_tracks, num_bytes_to_copy);
197         case AVRCP_MEDIA_ATTR_SONG_LENGTH_MS:
198             return avrcp_get_attribute_value_from_u32(connection, connection->song_length_ms, num_bytes_to_copy);
199         default:
200             break;
201     }
202     int attr_index = attr_id - 1;
203     if (connection->attribute_value_len == 0){
204         connection->attribute_value_len = avrcp_now_playing_info_attr_id_value_len(connection, attr_id);
205         connection->attribute_value_offset = 0;
206     }
207     *num_bytes_to_copy = connection->now_playing_info[attr_index].len - connection->attribute_value_offset;
208     return (uint8_t *) (connection->now_playing_info[attr_index].value + connection->attribute_value_offset);
209 }
210 
211 // TODO Review
212 static uint16_t avrcp_store_avctp_now_playing_info_fragment(avrcp_connection_t * connection, uint16_t packet_size, uint8_t * packet){
213     uint16_t num_free_bytes = packet_size;
214 
215     uint16_t bytes_stored = 0;
216 
217     while ((num_free_bytes > 0) && (connection->next_attr_id <= AVRCP_MEDIA_ATTR_SONG_LENGTH_MS)){
218         if ((connection->now_playing_info_attr_bitmap & (1 << (uint8_t)connection->next_attr_id)) == 0) {
219             connection->next_attr_id = (avrcp_media_attribute_id_t) (((int) connection->next_attr_id) + 1);
220             continue;
221         }
222 
223         // prepare attribute value
224         uint16_t num_bytes_to_copy;
225         uint8_t * attr_value_with_offset = avrcp_get_next_value_fragment_for_attribute_id(connection,
226                                                                                           connection->next_attr_id,
227                                                                                           &num_bytes_to_copy);
228 
229         // store header
230         if (connection->attribute_value_offset == 0){
231             // pack the whole attribute value header
232             if (connection->parser_attribute_header_pos == 0) {
233                 avrcp_target_pack_single_element_header(connection->parser_attribute_header, connection->next_attr_id,
234                                                         connection->attribute_value_len);
235             }
236         }
237 
238         if (connection->parser_attribute_header_pos < AVRCP_ATTRIBUTE_HEADER_LEN){
239             uint16_t num_header_bytes_to_store = btstack_min(num_free_bytes, AVRCP_ATTRIBUTE_HEADER_LEN - connection->parser_attribute_header_pos);
240             memcpy(packet + bytes_stored, connection->parser_attribute_header + connection->parser_attribute_header_pos, num_header_bytes_to_store);
241             connection->parser_attribute_header_pos += num_header_bytes_to_store;
242             bytes_stored += num_header_bytes_to_store;
243             num_free_bytes -= num_header_bytes_to_store;
244             connection->data_offset += num_header_bytes_to_store;
245 
246             if (num_free_bytes == 0){
247                 continue;
248             }
249         }
250 
251         // store value
252         uint16_t num_attr_value_bytes_to_store = btstack_min(num_free_bytes, connection->attribute_value_len - connection->attribute_value_offset);
253         memcpy(packet + bytes_stored, attr_value_with_offset, num_attr_value_bytes_to_store);
254         bytes_stored   += num_attr_value_bytes_to_store;
255         num_free_bytes -= num_attr_value_bytes_to_store;
256         connection->attribute_value_offset += num_attr_value_bytes_to_store;
257         connection->data_offset += num_attr_value_bytes_to_store;
258 
259         if (connection->attribute_value_offset == connection->attribute_value_len){
260             // C++ compatible version of connection->next_attr_id++
261             connection->next_attr_id = (avrcp_media_attribute_id_t) (((int) connection->next_attr_id) + 1);
262             connection->attribute_value_offset = 0;
263             connection->attribute_value_len = 0;
264             connection->parser_attribute_header_pos = 0;
265         }
266     }
267     return bytes_stored;
268 }
269 
270 static void avrcp_send_response_with_avctp_fragmentation(avrcp_connection_t * connection){
271     l2cap_reserve_packet_buffer();
272     uint8_t * packet = l2cap_get_outgoing_buffer();
273 
274     // transport header
275     // Transaction label | Packet_type | C/R | IPID (1 == invalid profile identifier)
276 
277     uint16_t max_payload_size;
278     connection->avctp_packet_type = avctp_get_packet_type(connection, &max_payload_size);
279     connection->packet_type = avrcp_get_packet_type(connection);
280 
281     // AVCTP header
282     // transport header : transaction label | Packet_type | C/R | IPID (1 == invalid profile identifier)
283     uint16_t pos = 0;
284     packet[pos++] = (connection->transaction_id << 4) | (connection->avctp_packet_type << 2) | (AVRCP_RESPONSE_FRAME << 1) | 0;
285 
286     uint8_t param_len = connection->data_len;
287 
288     if (connection->avctp_packet_type == AVCTP_START_PACKET){
289         uint8_t max_frame_size = btstack_min(l2cap_get_remote_mtu_for_local_cid(connection->l2cap_signaling_cid), AVRCP_MAX_AV_C_MESSAGE_FRAME_SIZE);
290         // first packet: max_payload_size
291         // rest packets
292         uint16_t num_payload_bytes = param_len - max_payload_size;
293         uint16_t frame_size_for_continue_packet = max_frame_size - avctp_get_num_bytes_for_header(AVCTP_CONTINUE_PACKET);
294         uint16_t num_avctp_packets = (num_payload_bytes + frame_size_for_continue_packet - 1)/frame_size_for_continue_packet + 1;
295         packet[pos++] = num_avctp_packets;
296     }
297 
298     uint16_t bytes_stored = 0;
299     uint8_t i;
300 
301     switch (connection->avctp_packet_type) {
302         case AVCTP_SINGLE_PACKET:
303         case AVCTP_START_PACKET:
304             // Profile IDentifier (PID)
305             packet[pos++] = BLUETOOTH_SERVICE_CLASS_AV_REMOTE_CONTROL >> 8;
306             packet[pos++] = BLUETOOTH_SERVICE_CLASS_AV_REMOTE_CONTROL & 0x00FF;
307 
308             // AVRCP message
309             // command_type
310             packet[pos++] = connection->command_type;
311             // subunit_type | subunit ID
312             packet[pos++] = (connection->subunit_type << 3) | connection->subunit_id;
313             // opcode
314             packet[pos++] = (uint8_t) connection->command_opcode;
315 
316             switch (connection->command_opcode) {
317                 case AVRCP_CMD_OPCODE_VENDOR_DEPENDENT:
318                     big_endian_store_24(packet, pos, connection->company_id);
319                     pos += 3;
320                     packet[pos++] = connection->pdu_id;
321                     // AVRCP packet type
322 
323                     packet[pos++] = (uint8_t)connection->packet_type;
324                     // parameter length
325                     big_endian_store_16(packet, pos, param_len);
326                     pos += 2;
327 
328                     switch (connection->pdu_id) {
329                         // message is small enough to fit the single packet, no need for extra check
330                         case AVRCP_PDU_ID_GET_CAPABILITIES:
331                             packet[pos++] = connection->data[0];
332                             connection->data_offset++;
333 
334                             packet[pos++] = connection->data[1];
335                             connection->data_offset++;
336 
337                             switch ((avrcp_capability_id_t) connection->data[0]) {
338                                 case AVRCP_CAPABILITY_ID_EVENT:
339                                     for (i = (uint8_t) AVRCP_NOTIFICATION_EVENT_FIRST_INDEX;
340                                          i < (uint8_t) AVRCP_NOTIFICATION_EVENT_LAST_INDEX; i++) {
341                                         if ((connection->target_supported_notifications & (1 << i)) == 0) {
342                                             continue;
343                                         }
344                                         packet[pos++] = i;
345                                         connection->data_offset++;
346                                     }
347                                     break;
348                                 case AVRCP_CAPABILITY_ID_COMPANY:
349                                     // use Bluetooth SIG as default company
350                                     if (connection->target_supported_companies_num == 0) {
351                                         little_endian_store_24(packet, pos, default_companies[0]);
352                                         pos += 3;
353                                         connection->data_offset += 3;
354                                     } else {
355                                         for (i = 0; i < connection->data[1]; i++) {
356                                             little_endian_store_24(packet, pos,
357                                                                    connection->target_supported_companies[i]);
358                                             pos += 3;
359                                             connection->data_offset += 3;
360                                         }
361                                     }
362                                     break;
363                                 default:
364                                     btstack_assert(false);
365                                     return;
366                             }
367                             l2cap_send_prepared(connection->l2cap_signaling_cid, pos);
368                             return;
369 
370                         case AVRCP_PDU_ID_GET_ELEMENT_ATTRIBUTES:
371 
372                             packet[pos++] = connection->num_attributes;
373                             max_payload_size--;
374 
375                             bytes_stored = avrcp_store_avctp_now_playing_info_fragment(connection, max_payload_size, packet + pos);
376 
377                             connection->avrcp_frame_bytes_sent += bytes_stored + pos;
378                             l2cap_send_prepared(connection->l2cap_signaling_cid, pos + bytes_stored);
379                             return;
380 
381                         default:
382                             break;
383                     }
384                     break;
385 
386                 case AVRCP_CMD_OPCODE_PASS_THROUGH:
387                     packet[pos++] = connection->operation_id;
388                     // parameter length
389                     packet[pos++] = (uint8_t) connection->data_len;
390                     pos += 2;
391                     break;
392                 case AVRCP_CMD_OPCODE_UNIT_INFO:
393                     break;
394                 case AVRCP_CMD_OPCODE_SUBUNIT_INFO:
395                     break;
396                 default:
397                     btstack_assert(false);
398                     return;
399             }
400             break;
401         case AVCTP_CONTINUE_PACKET:
402         case AVCTP_END_PACKET:
403             switch (connection->pdu_id) {
404                 case AVRCP_PDU_ID_GET_ELEMENT_ATTRIBUTES:
405                     bytes_stored = avrcp_store_avctp_now_playing_info_fragment(connection, max_payload_size, packet + pos);
406 
407                     connection->avrcp_frame_bytes_sent += bytes_stored + pos;
408                     l2cap_send_prepared(connection->l2cap_signaling_cid, pos + bytes_stored);
409                     return;
410 
411                 default:
412                     break;
413             }
414             break;
415         default:
416             btstack_assert(false);
417             return;
418     }
419 
420     // compare number of bytes to store with the remaining buffer size
421     uint16_t bytes_to_copy = btstack_min(connection->data_len - connection->data_offset, max_payload_size - pos);
422 
423     (void)memcpy(packet + pos, &connection->data[connection->data_offset], bytes_to_copy);
424     pos += bytes_to_copy;
425     connection->data_offset += bytes_to_copy;
426     connection->avrcp_frame_bytes_sent += pos;
427 
428     l2cap_send_prepared(connection->l2cap_signaling_cid, pos);
429 }
430 
431 static void avctp_send_reject_cmd_wrong_pid(avrcp_connection_t * connection){
432     l2cap_reserve_packet_buffer();
433     uint8_t * packet = l2cap_get_outgoing_buffer();
434 
435     // AVCTP header
436     // transport header : transaction label | Packet_type | C/R | IPID (1 == invalid profile identifier)
437     packet[0] = (connection->transaction_id << 4) | (AVRCP_SINGLE_PACKET << 2) | (AVRCP_RESPONSE_FRAME << 1) | 1;
438     big_endian_store_16(packet, 1, connection->cmd_operands[0]);
439     l2cap_send_prepared(connection->l2cap_signaling_cid, 3);
440 }
441 
442 static void avrcp_target_custome_command_data_init(avrcp_connection_t * connection,
443     avrcp_command_opcode_t opcode, avrcp_command_type_t command_type,
444     avrcp_subunit_type_t subunit_type, avrcp_subunit_id_t subunit_id,
445     avrcp_pdu_id_t pdu_id, uint32_t company_id){
446 
447     connection->command_opcode = opcode;
448     connection->command_type = command_type;
449     connection->subunit_type = subunit_type;
450     connection->subunit_id = subunit_id;
451     connection->company_id = company_id << 16;
452     connection->pdu_id = pdu_id;
453     connection->data = NULL;
454     connection->data_offset = 0;
455     connection->data_len = 0;
456 }
457 
458 static void avrcp_target_vendor_dependent_response_data_init(avrcp_connection_t * connection, avrcp_command_type_t command_type, avrcp_pdu_id_t pdu_id){
459     connection->command_opcode = AVRCP_CMD_OPCODE_VENDOR_DEPENDENT;
460     connection->subunit_type   = AVRCP_SUBUNIT_TYPE_PANEL;
461     connection->subunit_id     = AVRCP_SUBUNIT_ID;
462     connection->company_id     = BT_SIG_COMPANY_ID;
463 
464     connection->command_type = command_type;
465     connection->pdu_id = pdu_id;
466     connection->data = connection->cmd_operands;
467     connection->data_offset = 0;
468     connection->avrcp_frame_bytes_sent = 0;
469     connection->state = AVCTP_W2_SEND_RESPONSE;
470 }
471 
472 static void avrcp_target_pass_through_command_data_init(avrcp_connection_t * connection, avrcp_command_type_t command_type, avrcp_operation_id_t opid){
473     connection->command_opcode = AVRCP_CMD_OPCODE_PASS_THROUGH;
474     connection->subunit_type   = AVRCP_SUBUNIT_TYPE_PANEL;
475     connection->subunit_id     = AVRCP_SUBUNIT_ID;
476 
477     connection->command_type = command_type;
478     connection->company_id = 0;
479     connection->pdu_id = AVRCP_PDU_ID_UNDEFINED;
480     connection->operation_id = opid;
481 
482     connection->data = connection->cmd_operands;
483     connection->data_offset = 0;
484     connection->data_len = 0;
485 }
486 
487 
488 static uint8_t avrcp_target_vendor_dependent_response_accept(avrcp_connection_t * connection, avrcp_pdu_id_t pdu_id, uint8_t status){
489     avrcp_target_vendor_dependent_response_data_init(connection, AVRCP_CTYPE_RESPONSE_ACCEPTED, pdu_id);
490     connection->data_len = 1;
491     connection->data[0] = status;
492 
493     connection->accept_response = 1;
494     avrcp_request_can_send_now(connection, connection->l2cap_signaling_cid);
495     return ERROR_CODE_SUCCESS;
496 }
497 
498 static uint8_t avrcp_target_response_vendor_dependent_reject(avrcp_connection_t * connection, avrcp_pdu_id_t pdu_id, avrcp_status_code_t status){
499     avrcp_target_vendor_dependent_response_data_init(connection, AVRCP_CTYPE_RESPONSE_REJECTED, pdu_id);
500     connection->data_len = 1;
501     connection->data[0] = status;
502 
503     connection->state = AVCTP_W2_SEND_RESPONSE;
504     avrcp_request_can_send_now(connection, connection->l2cap_signaling_cid);
505     return ERROR_CODE_SUCCESS;
506 }
507 
508 static uint8_t avrcp_target_response_vendor_dependent_not_implemented(avrcp_connection_t * connection, avrcp_pdu_id_t pdu_id, uint8_t event_id){
509     avrcp_target_vendor_dependent_response_data_init(connection, AVRCP_CTYPE_RESPONSE_NOT_IMPLEMENTED, pdu_id);
510     connection->data_len = 1;
511     connection->data[0] = event_id;
512 
513     connection->state = AVCTP_W2_SEND_RESPONSE;
514     avrcp_request_can_send_now(connection, connection->l2cap_signaling_cid);
515     return ERROR_CODE_SUCCESS;
516 }
517 
518 static uint8_t avrcp_target_response_vendor_dependent_interim(avrcp_connection_t * connection, avrcp_pdu_id_t pdu_id, uint8_t event_id, const uint8_t * value, uint16_t value_len){
519     btstack_assert(value_len + 1 < AVRCP_MAX_COMMAND_PARAMETER_LENGTH);
520 
521     avrcp_target_vendor_dependent_response_data_init(connection, AVRCP_CTYPE_RESPONSE_INTERIM, pdu_id);
522     connection->data_len = 1 + value_len;
523     connection->data[0] = event_id;
524 
525     if (value && (value_len > 0)){
526         (void)memcpy(connection->data + 1, value, value_len);
527     }
528 
529     connection->state = AVCTP_W2_SEND_RESPONSE;
530     avrcp_request_can_send_now(connection, connection->l2cap_signaling_cid);
531     return ERROR_CODE_SUCCESS;
532 }
533 
534 static uint8_t avrcp_target_response_addressed_player_changed_interim(avrcp_connection_t * connection, avrcp_pdu_id_t pdu_id, uint8_t event_id){
535     avrcp_target_vendor_dependent_response_data_init(connection, AVRCP_CTYPE_RESPONSE_INTERIM, pdu_id);
536 
537     connection->data_len = 5;
538     connection->data[0] = event_id;
539     big_endian_store_16(connection->data, 1, connection->addressed_player_id);
540     big_endian_store_16(connection->data, 3, connection->uid_counter);
541 
542     connection->state = AVCTP_W2_SEND_RESPONSE;
543     avrcp_request_can_send_now(connection, connection->l2cap_signaling_cid);
544     return ERROR_CODE_SUCCESS;
545 }
546 
547 static uint8_t avrcp_target_pass_through_response(uint16_t avrcp_cid, avrcp_command_type_t ctype, avrcp_operation_id_t opid, uint8_t operands_length, uint8_t operand){
548     avrcp_connection_t * connection = avrcp_get_connection_for_avrcp_cid_for_role(AVRCP_TARGET, avrcp_cid);
549     if (!connection){
550         return ERROR_CODE_UNKNOWN_CONNECTION_IDENTIFIER;
551     }
552     avrcp_target_pass_through_command_data_init(connection, ctype, opid);
553 
554     if (operands_length == 1){
555         connection->data_len = 1;
556         connection->cmd_operands[0] = operand;
557     }
558 
559     connection->state = AVCTP_W2_SEND_RESPONSE;
560     avrcp_request_can_send_now(connection, connection->l2cap_signaling_cid);
561     return ERROR_CODE_SUCCESS;
562 }
563 
564 uint8_t avrcp_target_operation_rejected(uint16_t avrcp_cid, avrcp_operation_id_t opid, uint8_t operands_length, uint8_t operand){
565     return avrcp_target_pass_through_response(avrcp_cid, AVRCP_CTYPE_RESPONSE_REJECTED, opid, operands_length, operand);
566 }
567 
568 uint8_t avrcp_target_operation_accepted(uint16_t avrcp_cid, avrcp_operation_id_t opid, uint8_t operands_length, uint8_t operand){
569     return avrcp_target_pass_through_response(avrcp_cid, AVRCP_CTYPE_RESPONSE_ACCEPTED, opid, operands_length, operand);
570 }
571 
572 uint8_t avrcp_target_operation_not_implemented(uint16_t avrcp_cid, avrcp_operation_id_t opid, uint8_t operands_length, uint8_t operand){
573     return avrcp_target_pass_through_response(avrcp_cid, AVRCP_CTYPE_RESPONSE_ACCEPTED, opid, operands_length, operand);
574 }
575 
576 uint8_t avrcp_target_set_unit_info(uint16_t avrcp_cid, avrcp_subunit_type_t unit_type, uint32_t company_id){
577     avrcp_connection_t * connection = avrcp_get_connection_for_avrcp_cid_for_role(AVRCP_TARGET, avrcp_cid);
578     if (!connection){
579         return ERROR_CODE_UNKNOWN_CONNECTION_IDENTIFIER;
580     }
581     connection->unit_type = unit_type;
582     connection->company_id = company_id;
583     return ERROR_CODE_SUCCESS;
584 }
585 
586 uint8_t avrcp_target_set_subunit_info(uint16_t avrcp_cid, avrcp_subunit_type_t subunit_type, const uint8_t * subunit_info_data, uint16_t subunit_info_data_size){
587     avrcp_connection_t * connection = avrcp_get_connection_for_avrcp_cid_for_role(AVRCP_TARGET, avrcp_cid);
588     if (!connection){
589         return ERROR_CODE_UNKNOWN_CONNECTION_IDENTIFIER;
590     }
591     connection->subunit_info_type = subunit_type;
592     connection->subunit_info_data = subunit_info_data;
593     connection->subunit_info_data_size = subunit_info_data_size;
594     return ERROR_CODE_SUCCESS;
595 }
596 
597 // TODO Review
598 static uint8_t avrcp_target_unit_info(avrcp_connection_t * connection){
599     if (connection->state != AVCTP_CONNECTION_OPENED){
600         return ERROR_CODE_COMMAND_DISALLOWED;
601     }
602     connection->state = AVCTP_W2_SEND_RESPONSE;
603 
604     avrcp_target_custom_command_data_init(connection,
605                                           AVRCP_CMD_OPCODE_UNIT_INFO, AVRCP_CTYPE_RESPONSE_IMPLEMENTED_STABLE,
606                                           AVRCP_SUBUNIT_TYPE_UNIT, AVRCP_SUBUNIT_ID_IGNORE, AVRCP_PDU_ID_UNDEFINED,
607                                           connection->company_id);
608 
609     uint8_t unit = 0;
610     connection->data = connection->cmd_operands;
611     connection->data_len = 5;
612     connection->data[0] = 0x07;
613     connection->data[1] = (connection->unit_type << 4) | unit;
614     // company id is 3 bytes long
615     big_endian_store_24(connection->data, 2, connection->company_id);
616 
617     avrcp_request_can_send_now(connection, connection->l2cap_signaling_cid);
618     return ERROR_CODE_SUCCESS;
619 }
620 
621 // TODO Review
622 static uint8_t avrcp_target_subunit_info(avrcp_connection_t * connection, uint8_t offset){
623     if (connection->state != AVCTP_CONNECTION_OPENED) return ERROR_CODE_COMMAND_DISALLOWED;
624     if (offset >= 32) return AVRCP_STATUS_INVALID_PARAMETER;
625 
626     connection->state = AVCTP_W2_SEND_RESPONSE;
627 
628     avrcp_target_custom_command_data_init(connection, AVRCP_CMD_OPCODE_SUBUNIT_INFO,
629                                           AVRCP_CTYPE_RESPONSE_IMPLEMENTED_STABLE,
630                                           AVRCP_SUBUNIT_TYPE_UNIT, AVRCP_SUBUNIT_ID_IGNORE, AVRCP_PDU_ID_UNDEFINED,
631                                           connection->company_id);
632 
633     uint8_t page = offset / 4;
634     uint8_t extension_code = 7;
635     connection->data = connection->cmd_operands;
636     connection->data_len = 5;
637     connection->data[0] = (page << 4) | extension_code;
638 
639     // mark non-existent entries with 0xff
640     memset(&connection->cmd_operands[1], 0xFF, 4);
641     if ((connection->data != NULL) && (offset < connection->subunit_info_data_size)){
642         uint8_t bytes_to_copy = btstack_min(connection->subunit_info_data_size - offset, 4);
643         memcpy(&connection->data[1], &connection->subunit_info_data[offset], bytes_to_copy);
644     }
645 
646     avrcp_request_can_send_now(connection, connection->l2cap_signaling_cid);
647     return ERROR_CODE_SUCCESS;
648 }
649 
650 static uint8_t avrcp_target_response_vendor_dependent_supported_events(avrcp_connection_t * connection){
651     avrcp_target_vendor_dependent_response_data_init(connection, AVRCP_CTYPE_RESPONSE_IMPLEMENTED_STABLE, AVRCP_PDU_ID_GET_CAPABILITIES);
652     connection->state = AVCTP_W2_SEND_RESPONSE;
653 
654     uint8_t event_id;
655     uint8_t num_events = 0;
656     for (event_id = (uint8_t) AVRCP_NOTIFICATION_EVENT_FIRST_INDEX; event_id < (uint8_t) AVRCP_NOTIFICATION_EVENT_LAST_INDEX; event_id++){
657         if ((connection->target_supported_notifications & (1<<event_id)) == 0){
658             continue;
659         }
660         num_events++;
661     }
662 
663     connection->data[0] = AVRCP_CAPABILITY_ID_EVENT;
664     connection->data[1] = num_events;
665     connection->data_len = 2 + num_events;
666 
667     // fill the data later directly to the L2CAP outgoing buffer
668     avrcp_request_can_send_now(connection, connection->l2cap_signaling_cid);
669     return ERROR_CODE_SUCCESS;
670 }
671 
672 static uint8_t avrcp_target_response_vendor_dependent_supported_companies(avrcp_connection_t * connection){
673     avrcp_target_vendor_dependent_response_data_init(connection, AVRCP_CTYPE_RESPONSE_IMPLEMENTED_STABLE, AVRCP_PDU_ID_GET_CAPABILITIES);
674     connection->state = AVCTP_W2_SEND_RESPONSE;
675 
676     connection->data[0] = AVRCP_CAPABILITY_ID_COMPANY;
677     connection->data[1] = connection->target_supported_companies_num;
678     connection->data_len = 2 + connection->target_supported_companies_num * 3;
679 
680     // fill the data later directly to the L2CAP outgoing buffer and
681     // use Bluetooth SIG as default company
682     avrcp_request_can_send_now(connection, connection->l2cap_signaling_cid);
683     return ERROR_CODE_SUCCESS;
684 }
685 
686 uint8_t avrcp_target_support_event(uint16_t avrcp_cid, avrcp_notification_event_id_t event_id){
687     avrcp_connection_t * connection = avrcp_get_connection_for_avrcp_cid_for_role(AVRCP_TARGET, avrcp_cid);
688     if (!connection){
689         return ERROR_CODE_UNKNOWN_CONNECTION_IDENTIFIER;
690     }
691 
692     if ((event_id < (uint8_t)AVRCP_NOTIFICATION_EVENT_FIRST_INDEX) || (event_id > (uint8_t)AVRCP_NOTIFICATION_EVENT_LAST_INDEX)){
693         return ERROR_CODE_UNSUPPORTED_FEATURE_OR_PARAMETER_VALUE;
694     }
695 
696     connection->target_supported_notifications |= (1 << (uint8_t)event_id);
697     return ERROR_CODE_SUCCESS;
698 }
699 
700 uint8_t avrcp_target_support_companies(uint16_t avrcp_cid, uint8_t num_companies, const uint32_t *companies){
701     avrcp_connection_t * connection = avrcp_get_connection_for_avrcp_cid_for_role(AVRCP_TARGET, avrcp_cid);
702     if (!connection){
703         return ERROR_CODE_UNKNOWN_CONNECTION_IDENTIFIER;
704     }
705 
706     connection->target_supported_companies_num = num_companies;
707     connection->target_supported_companies     = companies;
708     return ERROR_CODE_SUCCESS;
709 }
710 
711 // TODO Review (use flags)
712 uint8_t avrcp_target_play_status(uint16_t avrcp_cid, uint32_t song_length_ms, uint32_t song_position_ms, avrcp_playback_status_t play_status){
713     avrcp_connection_t * connection = avrcp_get_connection_for_avrcp_cid_for_role(AVRCP_TARGET, avrcp_cid);
714     if (!connection){
715         return ERROR_CODE_UNKNOWN_CONNECTION_IDENTIFIER;
716     }
717     if (connection->state != AVCTP_CONNECTION_OPENED){
718         return ERROR_CODE_COMMAND_DISALLOWED;
719     }
720 
721     avrcp_target_vendor_dependent_response_data_init(connection, AVRCP_CTYPE_RESPONSE_IMPLEMENTED_STABLE, AVRCP_PDU_ID_GET_PLAY_STATUS);
722     connection->data_len = 9;
723     big_endian_store_32(connection->data, 0, song_length_ms);
724     big_endian_store_32(connection->data, 4, song_position_ms);
725     connection->data[8] = play_status;
726 
727     connection->state = AVCTP_W2_SEND_RESPONSE;
728     avrcp_request_can_send_now(connection, connection->l2cap_signaling_cid);
729     return ERROR_CODE_SUCCESS;
730 }
731 
732 static uint8_t avrcp_target_store_media_attr(avrcp_connection_t * connection, avrcp_media_attribute_id_t attr_id, const char * value){
733     int index = attr_id - 1;
734     if (!value) return AVRCP_STATUS_INVALID_PARAMETER;
735     connection->now_playing_info[index].value = (uint8_t*)value;
736     connection->now_playing_info[index].len   = strlen(value);
737     return ERROR_CODE_SUCCESS;
738 }
739 
740 uint8_t avrcp_target_set_playback_status(uint16_t avrcp_cid, avrcp_playback_status_t playback_status){
741     avrcp_connection_t * connection = avrcp_get_connection_for_avrcp_cid_for_role(AVRCP_TARGET, avrcp_cid);
742     if (!connection){
743         return ERROR_CODE_UNKNOWN_CONNECTION_IDENTIFIER;
744     }
745     if (connection->playback_status == playback_status){
746         return ERROR_CODE_SUCCESS;
747     }
748 
749     connection->playback_status = playback_status;
750     if (connection->notifications_enabled & (1 << AVRCP_NOTIFICATION_EVENT_PLAYBACK_STATUS_CHANGED)) {
751         connection->playback_status_changed = 1;
752         avrcp_request_can_send_now(connection, connection->l2cap_signaling_cid);
753     }
754     return ERROR_CODE_SUCCESS;
755 }
756 
757 uint8_t avrcp_target_set_now_playing_info(uint16_t avrcp_cid, const avrcp_track_t * current_track, uint16_t total_tracks){
758     avrcp_connection_t * connection = avrcp_get_connection_for_avrcp_cid_for_role(AVRCP_TARGET, avrcp_cid);
759     if (!connection){
760         return ERROR_CODE_UNKNOWN_CONNECTION_IDENTIFIER;
761     }
762     if (!current_track){
763         connection->track_selected = 0;
764         connection->playback_status = AVRCP_PLAYBACK_STATUS_ERROR;
765         return ERROR_CODE_COMMAND_DISALLOWED;
766     }
767 
768     (void)memcpy(connection->track_id, current_track->track_id, 8);
769     connection->song_length_ms = current_track->song_length_ms;
770     connection->track_nr = current_track->track_nr;
771     connection->total_tracks = total_tracks;
772     avrcp_target_store_media_attr(connection, AVRCP_MEDIA_ATTR_TITLE, current_track->title);
773     avrcp_target_store_media_attr(connection, AVRCP_MEDIA_ATTR_ARTIST, current_track->artist);
774     avrcp_target_store_media_attr(connection, AVRCP_MEDIA_ATTR_ALBUM, current_track->album);
775     avrcp_target_store_media_attr(connection, AVRCP_MEDIA_ATTR_GENRE, current_track->genre);
776 
777     connection->track_selected = 1;
778 
779     if (connection->notifications_enabled & (1 << AVRCP_NOTIFICATION_EVENT_TRACK_CHANGED)) {
780         connection->track_changed = 1;
781         avrcp_request_can_send_now(connection, connection->l2cap_signaling_cid);
782     }
783     return ERROR_CODE_SUCCESS;
784 }
785 
786 uint8_t avrcp_target_track_changed(uint16_t avrcp_cid, uint8_t * track_id){
787     avrcp_connection_t * connection = avrcp_get_connection_for_avrcp_cid_for_role(AVRCP_TARGET, avrcp_cid);
788     if (!connection){
789         return ERROR_CODE_UNKNOWN_CONNECTION_IDENTIFIER;
790     }
791     if (!track_id){
792         return ERROR_CODE_UNSUPPORTED_FEATURE_OR_PARAMETER_VALUE;
793     }
794 
795     (void)memcpy(connection->track_id, track_id, 8);
796     if (connection->notifications_enabled & (1 << AVRCP_NOTIFICATION_EVENT_TRACK_CHANGED)) {
797         connection->track_changed = 1;
798         avrcp_request_can_send_now(connection, connection->l2cap_signaling_cid);
799     }
800     return ERROR_CODE_SUCCESS;
801 }
802 
803 uint8_t avrcp_target_playing_content_changed(uint16_t avrcp_cid){
804     avrcp_connection_t * connection = avrcp_get_connection_for_avrcp_cid_for_role(AVRCP_TARGET, avrcp_cid);
805     if (!connection){
806         return ERROR_CODE_UNKNOWN_CONNECTION_IDENTIFIER;
807     }
808     if (connection->notifications_enabled & (1 << AVRCP_NOTIFICATION_EVENT_NOW_PLAYING_CONTENT_CHANGED)) {
809         connection->playing_content_changed = 1;
810         avrcp_request_can_send_now(connection, connection->l2cap_signaling_cid);
811     }
812     return ERROR_CODE_SUCCESS;
813 }
814 
815 uint8_t avrcp_target_addressed_player_changed(uint16_t avrcp_cid, uint16_t player_id, uint16_t uid_counter){
816     avrcp_connection_t * connection = avrcp_get_connection_for_avrcp_cid_for_role(AVRCP_TARGET, avrcp_cid);
817     if (!connection){
818         return ERROR_CODE_UNKNOWN_CONNECTION_IDENTIFIER;
819     }
820 
821     if (connection->addressed_player_id == player_id){
822         return ERROR_CODE_SUCCESS;
823     }
824 
825     connection->uid_counter = uid_counter;
826     connection->addressed_player_id = player_id;
827 
828     if (connection->notifications_enabled & (1 << AVRCP_NOTIFICATION_EVENT_ADDRESSED_PLAYER_CHANGED)) {
829         connection->addressed_player_changed = 1;
830         avrcp_request_can_send_now(connection, connection->l2cap_signaling_cid);
831     }
832     return ERROR_CODE_SUCCESS;
833 }
834 
835 uint8_t avrcp_target_battery_status_changed(uint16_t avrcp_cid, avrcp_battery_status_t battery_status){
836     avrcp_connection_t * connection = avrcp_get_connection_for_avrcp_cid_for_role(AVRCP_TARGET, avrcp_cid);
837     if (!connection){
838         return ERROR_CODE_UNKNOWN_CONNECTION_IDENTIFIER;
839     }
840     if (connection->battery_status == battery_status){
841         return ERROR_CODE_SUCCESS;
842     }
843 
844     connection->battery_status = battery_status;
845 
846     if (connection->notifications_enabled & (1 << AVRCP_NOTIFICATION_EVENT_BATT_STATUS_CHANGED)) {
847         connection->battery_status_changed = 1;
848         avrcp_request_can_send_now(connection, connection->l2cap_signaling_cid);
849     }
850     return ERROR_CODE_SUCCESS;
851 }
852 
853 uint8_t avrcp_target_adjust_absolute_volume(uint16_t avrcp_cid, uint8_t absolute_volume){
854     avrcp_connection_t * connection = avrcp_get_connection_for_avrcp_cid_for_role(AVRCP_TARGET, avrcp_cid);
855     if (!connection){
856         return ERROR_CODE_UNKNOWN_CONNECTION_IDENTIFIER;
857     }
858 
859     connection->absolute_volume = absolute_volume;
860     return ERROR_CODE_SUCCESS;
861 }
862 
863 uint8_t avrcp_target_volume_changed(uint16_t avrcp_cid, uint8_t absolute_volume){
864     avrcp_connection_t * connection = avrcp_get_connection_for_avrcp_cid_for_role(AVRCP_TARGET, avrcp_cid);
865     if (!connection){
866         return ERROR_CODE_UNKNOWN_CONNECTION_IDENTIFIER;
867     }
868     if (connection->absolute_volume == absolute_volume){
869         return ERROR_CODE_SUCCESS;
870     }
871 
872     connection->absolute_volume = absolute_volume;
873 
874     if (connection->notifications_enabled & (1 << AVRCP_NOTIFICATION_EVENT_VOLUME_CHANGED )) {
875         connection->notify_absolute_volume_changed = 1;
876         avrcp_request_can_send_now(connection, connection->l2cap_signaling_cid);
877     }
878     return ERROR_CODE_SUCCESS;
879 }
880 
881 static void avrcp_target_set_transaction_label_for_notification(avrcp_connection_t * connection, avrcp_notification_event_id_t notification, uint8_t transaction_label){
882     if (notification > AVRCP_NOTIFICATION_EVENT_MAX_VALUE) return;
883     connection->notifications_transaction_label[notification] = transaction_label;
884 }
885 
886 static uint8_t avrcp_target_get_transaction_label_for_notification(avrcp_connection_t * connection, avrcp_notification_event_id_t notification){
887     if (notification > AVRCP_NOTIFICATION_EVENT_MAX_VALUE) return 0;
888     return connection->notifications_transaction_label[notification];
889 }
890 
891 static bool avcrp_operation_id_is_valid(avrcp_operation_id_t operation_id){
892     if (operation_id < AVRCP_OPERATION_ID_RESERVED_1) return true;
893 
894     if (operation_id < AVRCP_OPERATION_ID_0) return false;
895     if (operation_id < AVRCP_OPERATION_ID_RESERVED_2) return true;
896 
897     if (operation_id < AVRCP_OPERATION_ID_CHANNEL_UP) return false;
898     if (operation_id < AVRCP_OPERATION_ID_RESERVED_3) return true;
899 
900     if (operation_id < AVRCP_OPERATION_ID_CHANNEL_UP) return false;
901     if (operation_id < AVRCP_OPERATION_ID_RESERVED_3) return true;
902 
903     if (operation_id < AVRCP_OPERATION_ID_SKIP) return false;
904     if (operation_id == AVRCP_OPERATION_ID_SKIP) return true;
905 
906     if (operation_id < AVRCP_OPERATION_ID_POWER) return false;
907     if (operation_id < AVRCP_OPERATION_ID_RESERVED_4) return true;
908 
909     if (operation_id < AVRCP_OPERATION_ID_ANGLE) return false;
910     if (operation_id < AVRCP_OPERATION_ID_RESERVED_5) return true;
911 
912     if (operation_id < AVRCP_OPERATION_ID_F1) return false;
913     if (operation_id < AVRCP_OPERATION_ID_RESERVED_6) return true;
914 
915     return false;
916 }
917 
918 
919 #ifdef ENABLE_AVCTP_FRAGMENTATION
920 static void avctp_reassemble_message(avrcp_connection_t * connection, avctp_packet_type_t packet_type, uint8_t *packet, uint16_t size){
921     // after header (transaction label and packet type)
922     uint16_t pos;
923     uint16_t bytes_to_store;
924 
925     switch (packet_type){
926         case AVCTP_START_PACKET:
927             if (size < 2) return;
928 
929             // store header
930             pos = 0;
931             connection->avctp_reassembly_buffer[pos] = packet[pos];
932             pos++;
933             connection->avctp_reassembly_size = pos;
934 
935             // NOTE: num packets not needed for reassembly, ignoring it does not pose security risk -> no need to store it
936             pos++;
937 
938             // PID in reassembled packet is at offset 1, it will be read later after the avctp_reassemble_message with AVCTP_END_PACKET is called
939 
940             bytes_to_store = btstack_min(size - pos, sizeof(connection->avctp_reassembly_buffer) - connection->avctp_reassembly_size);
941             memcpy(&connection->avctp_reassembly_buffer[connection->avctp_reassembly_size], &packet[pos], bytes_to_store);
942             connection->avctp_reassembly_size += bytes_to_store;
943             break;
944 
945         case AVCTP_CONTINUE_PACKET:
946         case AVCTP_END_PACKET:
947             if (size < 1) return;
948 
949             // store remaining data, ignore header
950             pos = 1;
951             bytes_to_store = btstack_min(size - pos, sizeof(connection->avctp_reassembly_buffer) - connection->avctp_reassembly_size);
952             memcpy(&connection->avctp_reassembly_buffer[connection->avctp_reassembly_size], &packet[pos], bytes_to_store);
953             connection->avctp_reassembly_size += bytes_to_store;
954             break;
955 
956         default:
957             return;
958     }
959 }
960 #endif
961 
962 static void avrcp_handle_l2cap_data_packet_for_signaling_connection(avrcp_connection_t * connection, uint8_t * packet, uint16_t size){
963     uint8_t avctp_header = packet[0];
964     connection->transaction_id = avctp_header >> 4;
965 
966     avctp_packet_type_t avctp_packet_type = (avctp_packet_type_t) ((avctp_header & 0x0F) >> 2);
967     switch (avctp_packet_type){
968         case AVCTP_SINGLE_PACKET:
969             break;
970 
971 #ifdef ENABLE_AVCTP_FRAGMENTATION
972         case AVCTP_START_PACKET:
973         case AVCTP_CONTINUE_PACKET:
974             avctp_reassemble_message(connection, avctp_packet_type, packet, size);
975             return;
976 
977         case AVCTP_END_PACKET:
978             avctp_reassemble_message(connection, avctp_packet_type, packet, size);
979 
980             packet = connection->avctp_reassembly_buffer;
981             size   = connection->avctp_reassembly_size;
982             break;
983 #endif
984         default:
985             return;
986     }
987 
988     if (size < 6u) return;
989 
990     uint16_t pid = big_endian_read_16(packet, 1);
991 
992     if (pid != BLUETOOTH_SERVICE_CLASS_AV_REMOTE_CONTROL){
993         log_info("Invalid pid 0x%02x, expected 0x%02x", pid, BLUETOOTH_SERVICE_CLASS_AV_REMOTE_CONTROL);
994         connection->reject_transport_header = true;
995         connection->invalid_pid = pid;
996         avrcp_request_can_send_now(connection, connection->l2cap_signaling_cid);
997         return;
998     }
999 
1000     // avrcp_subunit_type_t subunit_type = (avrcp_subunit_type_t) (packet[4] >> 3);
1001     // avrcp_subunit_id_t   subunit_id   = (avrcp_subunit_id_t) (packet[4] & 0x07);
1002 
1003     avrcp_command_opcode_t opcode = (avrcp_command_opcode_t) avrcp_cmd_opcode(packet,size);
1004 
1005     int pos = 6;
1006     uint16_t length;
1007     avrcp_pdu_id_t   pdu_id;
1008     // connection->data_len = 0;
1009     uint8_t offset;
1010     uint8_t operand;
1011     uint16_t event_mask;
1012     avrcp_operation_id_t operation_id;
1013 
1014     switch (opcode){
1015         case AVRCP_CMD_OPCODE_UNIT_INFO:
1016             avrcp_target_unit_info(connection);
1017             break;
1018         case AVRCP_CMD_OPCODE_SUBUNIT_INFO:
1019             if ((size - pos) < 3) return;
1020             // page: packet[pos] >> 4,
1021             offset =  4 * (packet[pos]>>4);
1022             // extension code (fixed 7) = packet[pos] & 0x0F
1023             // 4 bytes paga data, all 0xFF
1024             avrcp_target_subunit_info(connection, offset);
1025             break;
1026 
1027         case AVRCP_CMD_OPCODE_PASS_THROUGH:
1028             if (size < 8) return;
1029             log_info("AVRCP_OPERATION_ID 0x%02x, operands length %d", packet[6], packet[7]);
1030             operation_id = (avrcp_operation_id_t) (packet[6] & 0x7f);
1031             operand = 0;
1032             if ((packet[7] >= 1) && (size >= 9)){
1033                 operand = packet[8];
1034             }
1035 
1036             if (avcrp_operation_id_is_valid(operation_id)){
1037                 bool button_pressed = (packet[6] & 0x80) == 0;
1038 
1039                 avrcp_target_operation_accepted(connection->avrcp_cid, (avrcp_operation_id_t) packet[6], packet[7], operand);
1040                 avrcp_target_emit_operation(avrcp_target_context.avrcp_callback, connection->avrcp_cid,
1041                                                 operation_id, button_pressed, packet[7], operand);
1042             } else {
1043                 avrcp_target_operation_not_implemented(connection->avrcp_cid, (avrcp_operation_id_t) packet[6], packet[7], operand);
1044             }
1045             break;
1046 
1047 
1048         case AVRCP_CMD_OPCODE_VENDOR_DEPENDENT:
1049 
1050             if (size < 13) return;
1051 
1052             // pos = 6 - company id
1053             (void)memcpy(connection->cmd_operands, &packet[pos], 3);
1054             // connection->data_len = 3;
1055             pos += 3;
1056             // pos = 9
1057             pdu_id = (avrcp_pdu_id_t) packet[pos++];
1058             // 1 - reserved
1059             pos++;
1060             // 2-3 param length,
1061             length = big_endian_read_16(packet, pos);
1062             pos += 2;
1063             // pos = 13
1064             switch (pdu_id){
1065                 case AVRCP_PDU_ID_SET_ADDRESSED_PLAYER:{
1066                     if ((pos + 2) > size) return;
1067                     bool ok = length == 4;
1068                     if (avrcp_target_context.set_addressed_player_callback != NULL){
1069                         uint16_t player_id = big_endian_read_16(packet, pos);
1070                         ok = avrcp_target_context.set_addressed_player_callback(player_id);
1071                     }
1072                     if (ok){
1073                         avrcp_target_vendor_dependent_response_accept(connection, pdu_id, AVRCP_STATUS_SUCCESS);
1074                     } else {
1075                         avrcp_target_response_vendor_dependent_reject(connection, pdu_id, AVRCP_STATUS_INVALID_PLAYER_ID);
1076                     }
1077                     break;
1078                 }
1079                 case AVRCP_PDU_ID_GET_CAPABILITIES:{
1080                     avrcp_capability_id_t capability_id = (avrcp_capability_id_t) packet[pos];
1081                     switch (capability_id){
1082                         case AVRCP_CAPABILITY_ID_EVENT:
1083                              avrcp_target_response_vendor_dependent_supported_events(connection);
1084                             break;
1085                         case AVRCP_CAPABILITY_ID_COMPANY:
1086                             avrcp_target_response_vendor_dependent_supported_companies(connection);
1087                             break;
1088                         default:
1089                             avrcp_target_response_vendor_dependent_reject(connection, pdu_id, AVRCP_STATUS_INVALID_PARAMETER);
1090                             break;
1091                     }
1092                     break;
1093                 }
1094                 case AVRCP_PDU_ID_GET_PLAY_STATUS:
1095                     avrcp_target_emit_respond_vendor_dependent_query(avrcp_target_context.avrcp_callback, connection->avrcp_cid, AVRCP_SUBEVENT_PLAY_STATUS_QUERY);
1096                     break;
1097                 case AVRCP_PDU_ID_REQUEST_ABORT_CONTINUING_RESPONSE:
1098                     if ((pos + 1) > size) return;
1099                     connection->cmd_operands[0] = packet[pos];
1100                     connection->abort_continue_response = 1;
1101                     avrcp_request_can_send_now(connection, connection->l2cap_signaling_cid);
1102                     break;
1103                 case AVRCP_PDU_ID_REQUEST_CONTINUING_RESPONSE:
1104                     if ((pos + 1) > size) return;
1105                     if (packet[pos] != AVRCP_PDU_ID_GET_ELEMENT_ATTRIBUTES){
1106                         avrcp_target_response_vendor_dependent_reject(connection, pdu_id, AVRCP_STATUS_INVALID_COMMAND);
1107                         return;
1108                     }
1109                     connection->now_playing_info_response = true;
1110                     avrcp_request_can_send_now(connection, connection->l2cap_signaling_cid);
1111                     break;
1112                 case AVRCP_PDU_ID_GET_ELEMENT_ATTRIBUTES:{
1113                     if ((pos + 9) > size) return;
1114                     uint8_t play_identifier[8];
1115                     memset(play_identifier, 0, 8);
1116                     if (memcmp(&packet[pos], play_identifier, 8) != 0) {
1117                         avrcp_target_response_vendor_dependent_reject(connection, pdu_id, AVRCP_STATUS_INVALID_PARAMETER);
1118                         return;
1119                     }
1120                     pos += 8;
1121                     uint8_t attribute_count = packet[pos++];
1122                     connection->next_attr_id = AVRCP_MEDIA_ATTR_NONE;
1123                     if (!attribute_count){
1124                         connection->next_attr_id = AVRCP_MEDIA_ATTR_TITLE;
1125                         connection->now_playing_info_attr_bitmap = 0xFE;
1126                     } else {
1127                         int i;
1128                         connection->next_attr_id = AVRCP_MEDIA_ATTR_TITLE;
1129                         connection->now_playing_info_attr_bitmap = 0;
1130                         connection->num_attributes = 0;
1131                         if ((pos + attribute_count * 4) > size) return;
1132                         for (i=0; i < attribute_count; i++){
1133                             uint32_t attr_id = big_endian_read_32(packet, pos);
1134                             connection->now_playing_info_attr_bitmap |= (1 << attr_id);
1135                             pos += 4;
1136                         }
1137                     }
1138                     log_info("now_playing_info_attr_bitmap 0x%02x", connection->now_playing_info_attr_bitmap);
1139                     connection->num_attributes = count_set_bits_uint32(connection->now_playing_info_attr_bitmap);
1140                     connection->now_playing_info_response = true;
1141                     avrcp_request_can_send_now(connection, connection->l2cap_signaling_cid);
1142                     break;
1143                 }
1144                 case AVRCP_PDU_ID_REGISTER_NOTIFICATION:{
1145                     if ((pos + 1) > size) return;
1146                     avrcp_notification_event_id_t event_id = (avrcp_notification_event_id_t) packet[pos];
1147 
1148                     avrcp_target_set_transaction_label_for_notification(connection, event_id, connection->transaction_id);
1149 
1150                     if (event_id < AVRCP_NOTIFICATION_EVENT_PLAYBACK_STATUS_CHANGED ||
1151                         event_id > AVRCP_NOTIFICATION_EVENT_MAX_VALUE){
1152                         avrcp_target_response_vendor_dependent_reject(connection, pdu_id, AVRCP_STATUS_INVALID_PARAMETER);
1153                         return;
1154                     }
1155 
1156                     switch (event_id){
1157                         case AVRCP_NOTIFICATION_EVENT_AVAILABLE_PLAYERS_CHANGED:
1158                         case AVRCP_NOTIFICATION_EVENT_PLAYER_APPLICATION_SETTING_CHANGED:
1159                         case AVRCP_NOTIFICATION_EVENT_UIDS_CHANGED:
1160                         case AVRCP_NOTIFICATION_EVENT_TRACK_REACHED_END:
1161                         case AVRCP_NOTIFICATION_EVENT_TRACK_REACHED_START:
1162                         case AVRCP_NOTIFICATION_EVENT_PLAYBACK_POS_CHANGED:
1163                         case AVRCP_NOTIFICATION_EVENT_SYSTEM_STATUS_CHANGED:
1164                         case AVRCP_NOTIFICATION_EVENT_MAX_VALUE:
1165                             avrcp_target_response_vendor_dependent_not_implemented(connection, pdu_id, event_id);
1166                             return;
1167                         default:
1168                             break;
1169                     }
1170 
1171                     event_mask = (1 << event_id);
1172                     connection->notifications_enabled |= event_mask;
1173 
1174                     switch (event_id){
1175                         case AVRCP_NOTIFICATION_EVENT_TRACK_CHANGED:
1176                             if (connection->track_selected){
1177                                 avrcp_target_response_vendor_dependent_interim(connection, pdu_id, event_id, AVRCP_NOTIFICATION_TRACK_SELECTED, 8);
1178                             } else {
1179                                 avrcp_target_response_vendor_dependent_interim(connection, pdu_id, event_id, AVRCP_NOTIFICATION_TRACK_NOT_SELECTED, 8);
1180                             }
1181                             break;
1182                         case AVRCP_NOTIFICATION_EVENT_PLAYBACK_STATUS_CHANGED:
1183                             avrcp_target_response_vendor_dependent_interim(connection, pdu_id, event_id, (const uint8_t *)&connection->playback_status, 1);
1184                             break;
1185                         case AVRCP_NOTIFICATION_EVENT_NOW_PLAYING_CONTENT_CHANGED:
1186                             avrcp_target_response_vendor_dependent_interim(connection, pdu_id, event_id, NULL, 0);
1187                             break;
1188                         case AVRCP_NOTIFICATION_EVENT_VOLUME_CHANGED:
1189                             avrcp_target_response_vendor_dependent_interim(connection, pdu_id, event_id, (const uint8_t *)&connection->absolute_volume, 1);
1190                             break;
1191                         case AVRCP_NOTIFICATION_EVENT_BATT_STATUS_CHANGED:
1192                             avrcp_target_response_vendor_dependent_interim(connection, pdu_id, event_id, (const uint8_t *)&connection->battery_status, 1);
1193                             break;
1194                         case AVRCP_NOTIFICATION_EVENT_ADDRESSED_PLAYER_CHANGED:
1195                             avrcp_target_response_addressed_player_changed_interim(connection, pdu_id, event_id);
1196                             return;
1197                         default:
1198                             btstack_assert(false);
1199                             return;
1200                     }
1201                     break;
1202                 }
1203                 case AVRCP_PDU_ID_SET_ABSOLUTE_VOLUME: {
1204                     if ( (length != 1) || ((pos + 1) > size)){
1205                         avrcp_target_response_vendor_dependent_reject(connection, pdu_id, AVRCP_STATUS_INVALID_COMMAND);
1206                         break;
1207                     }
1208 
1209                     uint8_t absolute_volume = packet[pos];
1210                     if (absolute_volume < 0x80){
1211                         connection->absolute_volume = absolute_volume;
1212                     }
1213                     avrcp_target_emit_volume_changed(avrcp_target_context.avrcp_callback, connection->avrcp_cid, connection->absolute_volume);
1214                     avrcp_target_vendor_dependent_response_accept(connection, pdu_id, connection->absolute_volume);
1215                     break;
1216                 }
1217                 default:
1218                     log_info("AVRCP target: unhandled pdu id 0x%02x", pdu_id);
1219                     avrcp_target_response_vendor_dependent_reject(connection, pdu_id, AVRCP_STATUS_INVALID_COMMAND);
1220                     break;
1221             }
1222             break;
1223         default:
1224             log_info("AVRCP target: opcode 0x%02x not implemented", avrcp_cmd_opcode(packet,size));
1225             break;
1226     }
1227 }
1228 
1229 static void avrcp_target_notification_init(avrcp_connection_t * connection, avrcp_notification_event_id_t notification_id, uint8_t * value, uint16_t value_len){
1230     btstack_assert((value_len == 0) || (value != NULL));
1231 
1232     avrcp_target_vendor_dependent_response_data_init(connection, AVRCP_CTYPE_RESPONSE_CHANGED_STABLE, AVRCP_PDU_ID_REGISTER_NOTIFICATION);
1233     connection->transaction_id = avrcp_target_get_transaction_label_for_notification(connection, notification_id);
1234 
1235     connection->data_len = 1 + value_len;
1236     connection->data[0] = notification_id;
1237     if (value_len > 0){
1238         (void)memcpy(connection->data + 1, value, value_len);
1239     }
1240 }
1241 
1242 static void avrcp_target_notification_addressed_player_changed_init(avrcp_connection_t * connection){
1243     avrcp_target_vendor_dependent_response_data_init(connection, AVRCP_CTYPE_RESPONSE_CHANGED_STABLE, AVRCP_PDU_ID_REGISTER_NOTIFICATION);
1244     connection->transaction_id = avrcp_target_get_transaction_label_for_notification(connection, AVRCP_NOTIFICATION_EVENT_ADDRESSED_PLAYER_CHANGED);
1245 
1246     connection->data_len = 5;
1247     connection->data[0] = AVRCP_NOTIFICATION_EVENT_ADDRESSED_PLAYER_CHANGED;
1248     big_endian_store_16(connection->data, 1, connection->addressed_player_id);
1249     big_endian_store_16(connection->data, 3, connection->uid_counter);
1250 }
1251 
1252 
1253 static void avrcp_target_reset_notification(avrcp_connection_t * connection, avrcp_notification_event_id_t notification_id){
1254     if (notification_id < AVRCP_NOTIFICATION_EVENT_FIRST_INDEX || notification_id > AVRCP_NOTIFICATION_EVENT_LAST_INDEX){
1255         return;
1256     }
1257     connection->notifications_enabled &= ~(1 << notification_id);
1258     connection->notifications_transaction_label[notification_id] = 0;
1259 }
1260 
1261 static void avrcp_request_next_avctp_segment(avrcp_connection_t * connection){
1262     // AVCTP
1263     switch (connection->avctp_packet_type){
1264         case AVCTP_END_PACKET:
1265         case AVCTP_SINGLE_PACKET:
1266             connection->avrcp_frame_bytes_sent = 0;
1267             connection->data_offset = 0;
1268             connection->data_len = 0;
1269             connection->state = AVCTP_CONNECTION_OPENED;
1270             break;
1271         default:
1272             connection->state = AVCTP_W2_SEND_RESPONSE;
1273             avrcp_request_can_send_now(connection, connection->l2cap_signaling_cid);
1274             break;
1275     }
1276 }
1277 
1278 static void avrcp_target_packet_handler(uint8_t packet_type, uint16_t channel, uint8_t *packet, uint16_t size){
1279     avrcp_connection_t * connection;
1280     bool send_response = true;
1281     avrcp_notification_event_id_t notification_id = AVRCP_NOTIFICATION_EVENT_NONE;
1282 
1283     switch (packet_type){
1284         case L2CAP_DATA_PACKET:
1285             connection = avrcp_get_connection_for_l2cap_signaling_cid_for_role(AVRCP_TARGET, channel);
1286             avrcp_handle_l2cap_data_packet_for_signaling_connection(connection, packet, size);
1287             return;
1288 
1289         case HCI_EVENT_PACKET:
1290             if (hci_event_packet_get_type(packet) != L2CAP_EVENT_CAN_SEND_NOW){
1291                 return;
1292             }
1293 
1294             connection = avrcp_get_connection_for_l2cap_signaling_cid_for_role(AVRCP_TARGET, channel);
1295             if (connection == NULL){
1296                 return;
1297             }
1298 
1299             // START AVCTP
1300             if (connection->reject_transport_header){
1301                 connection->reject_transport_header = false;
1302                 avctp_send_reject_cmd_wrong_pid(connection);
1303                 connection->state = AVCTP_CONNECTION_OPENED;
1304                 return;
1305             }
1306             // END AVCTP
1307 
1308             if (connection->accept_response){
1309                 connection->accept_response = 0;
1310                 avrcp_target_vendor_dependent_response_data_init(connection, AVRCP_CTYPE_RESPONSE_ACCEPTED, AVRCP_PDU_ID_REQUEST_CONTINUING_RESPONSE);
1311                 break;
1312             }
1313 
1314             if (connection->abort_continue_response){
1315                 connection->abort_continue_response = 0;
1316                 connection->now_playing_info_response = false;
1317                 avrcp_target_vendor_dependent_response_data_init(connection, AVRCP_CTYPE_RESPONSE_ACCEPTED, AVRCP_PDU_ID_REQUEST_ABORT_CONTINUING_RESPONSE);
1318                 break;
1319             }
1320 
1321             if (connection->now_playing_info_response){
1322                 connection->now_playing_info_response = false;
1323                 avrcp_target_vendor_dependent_response_data_init(connection, AVRCP_CTYPE_RESPONSE_ACCEPTED, AVRCP_PDU_ID_GET_ELEMENT_ATTRIBUTES);
1324                 connection->data_len = avrcp_now_playing_info_value_len_with_headers(connection);
1325                 break;
1326             }
1327 
1328             if (connection->track_changed){
1329                 connection->track_changed = 0;
1330                 notification_id = AVRCP_NOTIFICATION_EVENT_TRACK_CHANGED;
1331                 avrcp_target_notification_init(connection, notification_id, connection->track_id, 8);
1332                 break;
1333             }
1334 
1335             if (connection->playback_status_changed){
1336                 connection->playback_status_changed = 0;
1337                 notification_id = AVRCP_NOTIFICATION_EVENT_PLAYBACK_STATUS_CHANGED;
1338                 uint8_t playback_status = (uint8_t) connection->playback_status;
1339                 avrcp_target_notification_init(connection, notification_id, &playback_status, 1);
1340                 break;
1341             }
1342 
1343             if (connection->playing_content_changed){
1344                 connection->playing_content_changed = 0;
1345                 notification_id = AVRCP_NOTIFICATION_EVENT_NOW_PLAYING_CONTENT_CHANGED;
1346                 avrcp_target_notification_init(connection, notification_id, NULL, avrcp_now_playing_info_value_len_with_headers(connection));
1347                 break;
1348             }
1349 
1350             if (connection->battery_status_changed){
1351                 connection->battery_status_changed = 0;
1352                 notification_id = AVRCP_NOTIFICATION_EVENT_BATT_STATUS_CHANGED;
1353                 avrcp_target_notification_init(connection, notification_id, (uint8_t *)&connection->battery_status, 1);
1354                 break;
1355             }
1356 
1357             if (connection->notify_absolute_volume_changed){
1358                 connection->notify_absolute_volume_changed = 0;
1359                 notification_id = AVRCP_NOTIFICATION_EVENT_VOLUME_CHANGED;
1360                 avrcp_target_notification_init(connection, notification_id, &connection->absolute_volume, 1);
1361                 break;
1362             }
1363 
1364             if (connection->addressed_player_changed){
1365                 connection->addressed_player_changed = 0;
1366                 notification_id = AVRCP_NOTIFICATION_EVENT_ADDRESSED_PLAYER_CHANGED;
1367                 avrcp_target_notification_addressed_player_changed_init(connection);
1368                 break;
1369             }
1370 
1371             send_response = false;
1372             break;
1373 
1374         default:
1375             return;
1376     }
1377 
1378     if (connection != NULL && (send_response || connection->state == AVCTP_W2_SEND_RESPONSE)){
1379         avrcp_send_response_with_avctp_fragmentation(connection);
1380         avrcp_target_reset_notification(connection, notification_id);
1381         avrcp_request_next_avctp_segment(connection);
1382     }
1383 }
1384 
1385 void avrcp_target_init(void){
1386     avrcp_target_context.role = AVRCP_TARGET;
1387     avrcp_target_context.packet_handler = avrcp_target_packet_handler;
1388     avrcp_register_target_packet_handler(&avrcp_target_packet_handler);
1389 }
1390 
1391 void avrcp_target_deinit(void){
1392     memset(&avrcp_target_context, 0, sizeof(avrcp_context_t));
1393 }
1394 
1395 void avrcp_target_register_packet_handler(btstack_packet_handler_t callback){
1396     btstack_assert(callback != NULL);
1397     avrcp_target_context.avrcp_callback = callback;
1398 }
1399 
1400 void avrcp_target_register_set_addressed_player_handler(bool (*callback)(uint16_t player_id)){
1401     btstack_assert(callback != NULL);
1402     avrcp_target_context.set_addressed_player_callback = callback;
1403 }
1404 
1405 
1406