xref: /btstack/src/classic/avrcp_target.c (revision b28dc8004dd8d4fb9020a6dcd2bc81f05d36a008)
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 #define AVRCP_ATTR_HEADER_LEN  8
55 
56 static const uint8_t AVRCP_NOTIFICATION_TRACK_SELECTED[] = {0,0,0,0,0,0,0,0};
57 static const uint8_t AVRCP_NOTIFICATION_TRACK_NOT_SELECTED[] = {0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF};
58 
59 avrcp_context_t avrcp_target_context;
60 
61 static int avrcp_target_supports_browsing(uint16_t target_supported_features){
62     return target_supported_features & AVRCP_FEATURE_MASK_BROWSING;
63 }
64 
65 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){
66     avrcp_create_sdp_record(0, service, service_record_handle, avrcp_target_supports_browsing(supported_features), supported_features, service_name, service_provider_name);
67 }
68 
69 static void
70 avrcp_target_emit_operation(btstack_packet_handler_t callback, uint16_t avrcp_cid, avrcp_operation_id_t operation_id,
71                             bool button_pressed, uint8_t operands_length, uint8_t operand) {
72     btstack_assert(callback != NULL);
73 
74     uint8_t event[9];
75     int pos = 0;
76     event[pos++] = HCI_EVENT_AVRCP_META;
77     event[pos++] = sizeof(event) - 2;
78     event[pos++] = AVRCP_SUBEVENT_OPERATION;
79     little_endian_store_16(event, pos, avrcp_cid);
80     pos += 2;
81     event[pos++] = operation_id;
82     event[pos++] = button_pressed ? 1 : 0;
83     event[pos++] = operands_length;
84     event[pos++] = operand;
85     (*callback)(HCI_EVENT_PACKET, 0, event, sizeof(event));
86 }
87 
88 static void avrcp_target_emit_volume_changed(btstack_packet_handler_t callback, uint16_t avrcp_cid, uint8_t absolute_volume){
89     btstack_assert(callback != NULL);
90 
91     uint8_t event[7];
92     int offset = 0;
93     event[offset++] = HCI_EVENT_AVRCP_META;
94     event[offset++] = sizeof(event) - 2;
95     event[offset++] = AVRCP_SUBEVENT_NOTIFICATION_VOLUME_CHANGED;
96     little_endian_store_16(event, offset, avrcp_cid);
97     offset += 2;
98     event[offset++] = AVRCP_CTYPE_NOTIFY;
99     event[offset++] = absolute_volume;
100     (*callback)(HCI_EVENT_PACKET, 0, event, sizeof(event));
101 }
102 
103 static void avrcp_target_emit_respond_vendor_dependent_query(btstack_packet_handler_t callback, uint16_t avrcp_cid, uint8_t subevent_id){
104     btstack_assert(callback != NULL);
105 
106     uint8_t event[5];
107     int pos = 0;
108     event[pos++] = HCI_EVENT_AVRCP_META;
109     event[pos++] = sizeof(event) - 2;
110     event[pos++] = subevent_id;
111     little_endian_store_16(event, pos, avrcp_cid);
112     (*callback)(HCI_EVENT_PACKET, 0, event, sizeof(event));
113 }
114 
115 // returns number of bytes stored
116 static uint16_t avrcp_target_pack_single_element_header(uint8_t * packet, uint16_t pos, avrcp_media_attribute_id_t attr_id, uint16_t attr_value_size){
117     btstack_assert(attr_id >= 1);
118     btstack_assert(attr_id <= AVRCP_MEDIA_ATTR_COUNT);
119 
120     big_endian_store_32(packet, pos, attr_id);
121     big_endian_store_16(packet, pos+4, RFC2978_CHARSET_MIB_UTF8);
122     big_endian_store_16(packet, pos+6, attr_value_size);
123     return 8;
124 }
125 
126 // returns number of bytes stored
127 static uint16_t avrcp_target_pack_single_element_attribute_number(uint8_t * packet, uint16_t pos, avrcp_media_attribute_id_t attr_id, uint32_t value){
128     uint16_t attr_value_length = sprintf((char *)(packet+pos+8), "%0" PRIu32, value);
129     (void) avrcp_target_pack_single_element_header(packet, pos, attr_id, attr_value_length);
130     return 8 + attr_value_length;
131 }
132 
133 // returns number of bytes stored
134 static uint16_t avrcp_target_pack_single_element_attribute_string_fragment(uint8_t * packet, uint16_t pos, avrcp_media_attribute_id_t attr_id, uint8_t * attr_value, uint16_t attr_value_to_copy, uint16_t attr_value_size, bool header){
135     if (attr_value_size == 0) return 0;
136     uint16_t bytes_stored = 0;
137     if (header){
138         bytes_stored += avrcp_target_pack_single_element_header(packet, pos, attr_id, attr_value_size);
139     }
140     (void)memcpy(packet + pos + bytes_stored, attr_value, attr_value_to_copy);
141     bytes_stored += attr_value_to_copy;
142     return bytes_stored;
143 }
144 
145 static int avrcp_target_abort_continue_response(uint16_t cid, avrcp_connection_t * connection){
146     uint16_t pos = 0;
147     l2cap_reserve_packet_buffer();
148     uint8_t * packet = l2cap_get_outgoing_buffer();
149 
150     connection->command_opcode  = AVRCP_CMD_OPCODE_VENDOR_DEPENDENT;
151     connection->command_type    = AVRCP_CTYPE_RESPONSE_ACCEPTED;
152     connection->subunit_type    = AVRCP_SUBUNIT_TYPE_PANEL;
153     connection->subunit_id      = AVRCP_SUBUNIT_ID;
154 
155     packet[pos++] = (connection->transaction_id << 4) | (AVRCP_SINGLE_PACKET << 2) | (AVRCP_RESPONSE_FRAME << 1) | 0;
156     // Profile IDentifier (PID)
157     packet[pos++] = BLUETOOTH_SERVICE_CLASS_AV_REMOTE_CONTROL >> 8;
158     packet[pos++] = BLUETOOTH_SERVICE_CLASS_AV_REMOTE_CONTROL & 0x00FF;
159 
160     // command_type
161     packet[pos++] = connection->command_type;
162     // subunit_type | subunit ID
163     packet[pos++] = (connection->subunit_type << 3) | connection->subunit_id;
164     // opcode
165     packet[pos++] = (uint8_t)connection->command_opcode;
166 
167     // company id is 3 bytes long
168     big_endian_store_24(packet, pos, BT_SIG_COMPANY_ID);
169     pos += 3;
170 
171     packet[pos++] = AVRCP_PDU_ID_REQUEST_ABORT_CONTINUING_RESPONSE;
172 
173     // reserve byte for packet type
174     packet[pos++] = AVRCP_SINGLE_PACKET;
175     big_endian_store_16(packet, pos, 0);
176     pos += 2;
177     return l2cap_send_prepared(cid, pos);
178 }
179 
180 static int avrcp_target_send_now_playing_info(uint16_t cid, avrcp_connection_t * connection){
181     uint16_t pos = 0;
182     l2cap_reserve_packet_buffer();
183     uint8_t * packet = l2cap_get_outgoing_buffer();
184     uint16_t  size   = l2cap_get_remote_mtu_for_local_cid(connection->l2cap_signaling_cid);
185 
186     packet[pos++] = (connection->transaction_id << 4) | (AVRCP_SINGLE_PACKET << 2) | (AVRCP_RESPONSE_FRAME << 1) | 0;
187     // Profile IDentifier (PID)
188     packet[pos++] = BLUETOOTH_SERVICE_CLASS_AV_REMOTE_CONTROL >> 8;
189     packet[pos++] = BLUETOOTH_SERVICE_CLASS_AV_REMOTE_CONTROL & 0x00FF;
190 
191     // command_type
192     packet[pos++] = connection->command_type;
193     // subunit_type | subunit ID
194     packet[pos++] = (connection->subunit_type << 3) | connection->subunit_id;
195     // opcode
196     packet[pos++] = (uint8_t)connection->command_opcode;
197 
198     // company id is 3 bytes long
199     big_endian_store_24(packet, pos, BT_SIG_COMPANY_ID);
200     pos += 3;
201 
202     packet[pos++] = AVRCP_PDU_ID_GET_ELEMENT_ATTRIBUTES;
203 
204     // reserve byte for packet type
205     uint8_t pos_packet_type = pos;
206     pos++;
207 
208     uint16_t playing_info_buffer_len_position = pos;
209     pos += 2;
210     if (connection->next_attr_id == AVRCP_MEDIA_ATTR_NONE){
211         packet[pos_packet_type] = AVRCP_SINGLE_PACKET;
212         connection->packet_type = AVRCP_SINGLE_PACKET;
213         packet[pos++] = count_set_bits_uint32(connection->now_playing_info_attr_bitmap);
214         connection->next_attr_id = AVRCP_MEDIA_ATTR_ALL;
215     }
216 
217     uint8_t fragmented = 0;
218     int num_free_bytes = size - pos - 2;
219     uint8_t MAX_NUMBER_ATTR_LEN = 10;
220 
221     while (!fragmented && (num_free_bytes > 0) && (connection->next_attr_id <= AVRCP_MEDIA_ATTR_SONG_LENGTH_MS)){
222         avrcp_media_attribute_id_t attr_id = connection->next_attr_id;
223         int attr_index = attr_id - 1;
224 
225         if (connection->now_playing_info_attr_bitmap & (1 << attr_id)){
226             int num_written_bytes = 0;
227             int num_bytes_to_write = 0;
228             switch (attr_id){
229                 case AVRCP_MEDIA_ATTR_ALL:
230                 case AVRCP_MEDIA_ATTR_NONE:
231                     break;
232                 case AVRCP_MEDIA_ATTR_TRACK:
233                     num_bytes_to_write = AVRCP_ATTR_HEADER_LEN + MAX_NUMBER_ATTR_LEN;
234                     if (num_free_bytes >= num_bytes_to_write){
235                         num_written_bytes = avrcp_target_pack_single_element_attribute_number(packet, pos, attr_id, connection->track_nr);
236                         break;
237                     }
238                     fragmented = 1;
239                     connection->attribute_value_offset = 0;
240                     break;
241                 case AVRCP_MEDIA_ATTR_TOTAL_NUM_ITEMS:
242                     num_bytes_to_write = AVRCP_ATTR_HEADER_LEN + MAX_NUMBER_ATTR_LEN;
243                     if (num_free_bytes >= num_bytes_to_write){
244                         num_written_bytes = avrcp_target_pack_single_element_attribute_number(packet, pos, attr_id, connection->total_tracks);
245                         break;
246                     }
247                     fragmented = 1;
248                     connection->attribute_value_offset = 0;
249                     break;
250                 case AVRCP_MEDIA_ATTR_SONG_LENGTH_MS:
251                     num_bytes_to_write = AVRCP_ATTR_HEADER_LEN + MAX_NUMBER_ATTR_LEN;
252                     if (num_free_bytes >= num_bytes_to_write){
253                         num_written_bytes = avrcp_target_pack_single_element_attribute_number(packet, pos, attr_id, connection->song_length_ms);
254                         break;
255                     }
256                     fragmented = 1;
257                     connection->attribute_value_offset = 0;
258                     break;
259                 default:{
260                     bool      header = connection->attribute_value_offset == 0;
261                     uint8_t * attr_value =     (uint8_t *) (connection->now_playing_info[attr_index].value + connection->attribute_value_offset);
262                     uint16_t  attr_value_len = connection->now_playing_info[attr_index].len - connection->attribute_value_offset;
263 
264                     num_bytes_to_write = attr_value_len + (header * AVRCP_ATTR_HEADER_LEN);
265                     if (num_bytes_to_write <= num_free_bytes){
266                         connection->attribute_value_offset = 0;
267                         num_written_bytes = num_bytes_to_write;
268                         avrcp_target_pack_single_element_attribute_string_fragment(packet, pos, attr_id, attr_value, attr_value_len, connection->now_playing_info[attr_index].len, header);
269                         break;
270                     }
271                     fragmented = 1;
272                     num_written_bytes = num_free_bytes;
273                     attr_value_len = num_free_bytes - (header * AVRCP_ATTR_HEADER_LEN);
274                     avrcp_target_pack_single_element_attribute_string_fragment(packet, pos, attr_id, attr_value, attr_value_len, connection->now_playing_info[attr_index].len, header);
275                     connection->attribute_value_offset += attr_value_len;
276                     break;
277                 }
278             }
279             pos += num_written_bytes;
280             num_free_bytes -= num_written_bytes;
281         }
282         if (!fragmented){
283             // C++ compatible version of connection->next_attr_id++
284             connection->next_attr_id = (avrcp_media_attribute_id_t) (((int) connection->next_attr_id) + 1);
285         }
286     }
287 
288     if (fragmented){
289         switch (connection->packet_type){
290             case AVRCP_SINGLE_PACKET:
291                 connection->packet_type = AVRCP_START_PACKET;
292                 break;
293             default:
294                 connection->packet_type = AVRCP_CONTINUE_PACKET;
295                 break;
296         }
297     } else {
298         if (connection->next_attr_id >= AVRCP_MEDIA_ATTR_SONG_LENGTH_MS){ // DONE
299             if (connection->packet_type != AVRCP_SINGLE_PACKET){
300                 connection->packet_type = AVRCP_END_PACKET;
301             }
302         }
303     }
304     packet[pos_packet_type] = connection->packet_type;
305     // store attr value length
306     big_endian_store_16(packet, playing_info_buffer_len_position, pos - playing_info_buffer_len_position - 2);
307     return l2cap_send_prepared(cid, size);
308 }
309 
310 
311 
312 static int avrcp_target_send_response(uint16_t cid, avrcp_connection_t * connection){
313     int pos = 0;
314     l2cap_reserve_packet_buffer();
315     uint8_t * packet = l2cap_get_outgoing_buffer();
316 
317     // transport header
318     // Transaction label | Packet_type | C/R | IPID (1 == invalid profile identifier)
319 
320     // TODO: check for fragmentation
321     connection->packet_type = AVRCP_SINGLE_PACKET;
322 
323     packet[pos++] = (connection->transaction_id << 4) | (connection->packet_type << 2) | (AVRCP_RESPONSE_FRAME << 1) | 0;
324     // Profile IDentifier (PID)
325     packet[pos++] = BLUETOOTH_SERVICE_CLASS_AV_REMOTE_CONTROL >> 8;
326     packet[pos++] = BLUETOOTH_SERVICE_CLASS_AV_REMOTE_CONTROL & 0x00FF;
327     // command_type
328     packet[pos++] = connection->command_type;
329     // subunit_type | subunit ID
330     packet[pos++] = (connection->subunit_type << 3) | connection->subunit_id;
331     // opcode
332     packet[pos++] = (uint8_t)connection->command_opcode;
333 
334     (void)memcpy(packet + pos, connection->cmd_operands,
335                  connection->cmd_operands_length);
336     pos += connection->cmd_operands_length;
337 
338     return l2cap_send_prepared(cid, pos);
339 }
340 
341 static void avrcp_target_response_setup(avrcp_connection_t * connection, avrcp_command_type_t command_type, avrcp_subunit_type_t subunit_type, avrcp_subunit_id_t subunit_id,
342                                         avrcp_command_opcode_t opcode){
343     connection->command_type = command_type;
344     connection->subunit_type = subunit_type;
345     connection->subunit_id =   subunit_id;
346     connection->command_opcode = opcode;
347 }
348 
349 static uint8_t avrcp_target_response_accept(avrcp_connection_t * connection, avrcp_subunit_type_t subunit_type, avrcp_subunit_id_t subunit_id, avrcp_command_opcode_t opcode, avrcp_pdu_id_t pdu_id, uint8_t status){
350     // AVRCP_CTYPE_RESPONSE_REJECTED
351     avrcp_target_response_setup(connection, AVRCP_CTYPE_RESPONSE_ACCEPTED, subunit_type, subunit_id, opcode);
352     // company id is 3 bytes long
353     int pos = connection->cmd_operands_length;
354     connection->cmd_operands[pos++] = pdu_id;
355     connection->cmd_operands[pos++] = 0;
356     // param length
357     big_endian_store_16(connection->cmd_operands, pos, 1);
358     pos += 2;
359     connection->cmd_operands[pos++] = status;
360     connection->cmd_operands_length = pos;
361     connection->accept_response = 1;
362     avrcp_request_can_send_now(connection, connection->l2cap_signaling_cid);
363     return ERROR_CODE_SUCCESS;
364 }
365 
366 static uint8_t avrcp_target_response_reject(avrcp_connection_t * connection, avrcp_subunit_type_t subunit_type, avrcp_subunit_id_t subunit_id, avrcp_command_opcode_t opcode, avrcp_pdu_id_t pdu_id, avrcp_status_code_t status){
367     // AVRCP_CTYPE_RESPONSE_REJECTED
368     avrcp_target_response_setup(connection, AVRCP_CTYPE_RESPONSE_REJECTED, subunit_type, subunit_id, opcode);
369     // company id is 3 bytes long
370     int pos = connection->cmd_operands_length;
371     connection->cmd_operands[pos++] = pdu_id;
372     connection->cmd_operands[pos++] = 0;
373     // param length
374     big_endian_store_16(connection->cmd_operands, pos, 1);
375     pos += 2;
376     connection->cmd_operands[pos++] = status;
377     connection->cmd_operands_length = pos;
378     connection->state = AVCTP_W2_SEND_RESPONSE;
379     avrcp_request_can_send_now(connection, connection->l2cap_signaling_cid);
380     return ERROR_CODE_SUCCESS;
381 }
382 
383 static uint8_t avrcp_target_response_not_implemented(avrcp_connection_t * connection, avrcp_subunit_type_t subunit_type, avrcp_subunit_id_t subunit_id, avrcp_command_opcode_t opcode, avrcp_pdu_id_t pdu_id, uint8_t event_id){
384     avrcp_target_response_setup(connection, AVRCP_CTYPE_RESPONSE_NOT_IMPLEMENTED, subunit_type, subunit_id, opcode);
385     // company id is 3 bytes long
386     int pos = connection->cmd_operands_length;
387     connection->cmd_operands[pos++] = pdu_id;
388     connection->cmd_operands[pos++] = 0;
389     // param length
390     big_endian_store_16(connection->cmd_operands, pos, 1);
391     pos += 2;
392     connection->cmd_operands[pos++] = event_id;
393     connection->cmd_operands_length = pos;
394 
395     connection->state = AVCTP_W2_SEND_RESPONSE;
396     avrcp_request_can_send_now(connection, connection->l2cap_signaling_cid);
397     return ERROR_CODE_SUCCESS;
398 }
399 
400 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){
401 
402     // company id is 3 bytes long
403     int pos = connection->cmd_operands_length;
404     connection->cmd_operands[pos++] = pdu_id;
405     connection->cmd_operands[pos++] = 0;
406     // param length
407     big_endian_store_16(connection->cmd_operands, pos, 1 + value_len);
408     pos += 2;
409     connection->cmd_operands[pos++] = event_id;
410     if (value && (value_len > 0)){
411         (void)memcpy(connection->cmd_operands + pos, value, value_len);
412         pos += value_len;
413     }
414     connection->cmd_operands_length = pos;
415     connection->state = AVCTP_W2_SEND_RESPONSE;
416     avrcp_request_can_send_now(connection, connection->l2cap_signaling_cid);
417     return ERROR_CODE_SUCCESS;
418 }
419 
420 static uint8_t avrcp_target_response_addressed_player_changed_interim(avrcp_connection_t * connection, avrcp_subunit_type_t subunit_type, avrcp_subunit_id_t subunit_id, avrcp_command_opcode_t opcode, avrcp_pdu_id_t pdu_id){
421     avrcp_target_response_setup(connection, AVRCP_CTYPE_RESPONSE_INTERIM, subunit_type, subunit_id, opcode);
422 
423     // company id is 3 bytes long
424     int pos = connection->cmd_operands_length;
425     connection->cmd_operands[pos++] = pdu_id;
426     connection->cmd_operands[pos++] = 0;
427     // param length
428     big_endian_store_16(connection->cmd_operands, pos, 5);
429     pos += 2;
430     connection->cmd_operands[pos++] = AVRCP_NOTIFICATION_EVENT_ADDRESSED_PLAYER_CHANGED;
431     big_endian_read_16( &connection->cmd_operands[pos], connection->addressed_player_id);
432     pos += 2;
433     big_endian_read_16( &connection->cmd_operands[pos], connection->uid_counter);
434     pos += 2;
435 
436     connection->cmd_operands_length = pos;
437     connection->state = AVCTP_W2_SEND_RESPONSE;
438     avrcp_request_can_send_now(connection, connection->l2cap_signaling_cid);
439     return ERROR_CODE_SUCCESS;
440 }
441 
442 static uint8_t avrcp_target_pass_through_response(uint16_t avrcp_cid, avrcp_command_type_t cmd_type, avrcp_operation_id_t opid, uint8_t operands_length, uint8_t operand){
443     avrcp_connection_t * connection = avrcp_get_connection_for_avrcp_cid_for_role(AVRCP_TARGET, avrcp_cid);
444     if (!connection){
445         return ERROR_CODE_UNKNOWN_CONNECTION_IDENTIFIER;
446     }
447     avrcp_target_response_setup(connection, cmd_type, AVRCP_SUBUNIT_TYPE_PANEL, AVRCP_SUBUNIT_ID, AVRCP_CMD_OPCODE_PASS_THROUGH);
448 
449     int pos = 0;
450     connection->cmd_operands[pos++] = opid;
451     connection->cmd_operands[pos++] = operands_length;
452     if (operands_length == 1){
453         connection->cmd_operands[pos++] = operand;
454     }
455     connection->cmd_operands_length = pos;
456 
457     connection->state = AVCTP_W2_SEND_RESPONSE;
458     avrcp_request_can_send_now(connection, connection->l2cap_signaling_cid);
459     return ERROR_CODE_SUCCESS;
460 }
461 
462 uint8_t avrcp_target_operation_rejected(uint16_t avrcp_cid, avrcp_operation_id_t opid, uint8_t operands_length, uint8_t operand){
463     return avrcp_target_pass_through_response(avrcp_cid, AVRCP_CTYPE_RESPONSE_REJECTED, opid, operands_length, operand);
464 }
465 
466 uint8_t avrcp_target_operation_accepted(uint16_t avrcp_cid, avrcp_operation_id_t opid, uint8_t operands_length, uint8_t operand){
467     return avrcp_target_pass_through_response(avrcp_cid, AVRCP_CTYPE_RESPONSE_ACCEPTED, opid, operands_length, operand);
468 }
469 
470 uint8_t avrcp_target_operation_not_implemented(uint16_t avrcp_cid, avrcp_operation_id_t opid, uint8_t operands_length, uint8_t operand){
471     return avrcp_target_pass_through_response(avrcp_cid, AVRCP_CTYPE_RESPONSE_ACCEPTED, opid, operands_length, operand);
472 }
473 
474 uint8_t avrcp_target_set_unit_info(uint16_t avrcp_cid, avrcp_subunit_type_t unit_type, uint32_t company_id){
475     avrcp_connection_t * connection = avrcp_get_connection_for_avrcp_cid_for_role(AVRCP_TARGET, avrcp_cid);
476     if (!connection){
477         return ERROR_CODE_UNKNOWN_CONNECTION_IDENTIFIER;
478     }
479     connection->unit_type = unit_type;
480     connection->company_id = company_id;
481     return ERROR_CODE_SUCCESS;
482 }
483 
484 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){
485     avrcp_connection_t * connection = avrcp_get_connection_for_avrcp_cid_for_role(AVRCP_TARGET, avrcp_cid);
486     if (!connection){
487         return ERROR_CODE_UNKNOWN_CONNECTION_IDENTIFIER;
488     }
489     connection->subunit_info_type = subunit_type;
490     connection->subunit_info_data = subunit_info_data;
491     connection->subunit_info_data_size = subunit_info_data_size;
492     return ERROR_CODE_SUCCESS;
493 }
494 
495 static uint8_t avrcp_target_unit_info(avrcp_connection_t * connection){
496     if (connection->state != AVCTP_CONNECTION_OPENED) return ERROR_CODE_COMMAND_DISALLOWED;
497 
498     uint8_t unit = 0;
499     connection->command_type = AVRCP_CTYPE_RESPONSE_IMPLEMENTED_STABLE;
500     connection->subunit_type = AVRCP_SUBUNIT_TYPE_UNIT; //vendor unique
501     connection->subunit_id =   AVRCP_SUBUNIT_ID_IGNORE;
502     connection->command_opcode = AVRCP_CMD_OPCODE_UNIT_INFO;
503 
504     connection->cmd_operands_length = 5;
505     connection->cmd_operands[0] = 0x07;
506     connection->cmd_operands[1] = (connection->unit_type << 4) | unit;
507     // company id is 3 bytes long
508     big_endian_store_32(connection->cmd_operands, 2, connection->company_id);
509 
510     connection->state = AVCTP_W2_SEND_RESPONSE;
511     avrcp_request_can_send_now(connection, connection->l2cap_signaling_cid);
512     return ERROR_CODE_SUCCESS;
513 }
514 
515 
516 static uint8_t avrcp_target_subunit_info(avrcp_connection_t * connection, uint8_t offset){
517     if (connection->state != AVCTP_CONNECTION_OPENED) return ERROR_CODE_COMMAND_DISALLOWED;
518     if (offset >= 32) return AVRCP_STATUS_INVALID_PARAMETER;
519 
520     connection->command_opcode = AVRCP_CMD_OPCODE_SUBUNIT_INFO;
521     connection->command_type = AVRCP_CTYPE_RESPONSE_IMPLEMENTED_STABLE;
522     connection->subunit_type = AVRCP_SUBUNIT_TYPE_UNIT; //vendor unique
523     connection->subunit_id =   AVRCP_SUBUNIT_ID_IGNORE;
524 
525     uint8_t page = offset / 4;
526     uint8_t extension_code = 7;
527     connection->cmd_operands_length = 5;
528     connection->cmd_operands[0] = (page << 4) | extension_code;
529 
530     // mark non-existent entries with 0xff
531     memset(&connection->cmd_operands[1], 0xff, 4);
532     if ((connection->subunit_info_data != NULL) && (offset < connection->subunit_info_data_size)){
533         uint8_t bytes_to_copy = btstack_min(connection->subunit_info_data_size - offset, 4);
534         memcpy(&connection->cmd_operands[1], &connection->subunit_info_data[offset], bytes_to_copy);
535     }
536 
537     connection->state = AVCTP_W2_SEND_RESPONSE;
538     avrcp_request_can_send_now(connection, connection->l2cap_signaling_cid);
539     return ERROR_CODE_SUCCESS;
540 }
541 
542 static uint8_t avrcp_prepare_vendor_dependent_response_for_connection(avrcp_connection_t * connection, avrcp_pdu_id_t pdu_id, uint16_t param_length){
543     if (!connection){
544         return ERROR_CODE_UNKNOWN_CONNECTION_IDENTIFIER;
545     }
546     if (connection->state != AVCTP_CONNECTION_OPENED){
547         return ERROR_CODE_COMMAND_DISALLOWED;
548     }
549     connection->command_opcode  = AVRCP_CMD_OPCODE_VENDOR_DEPENDENT;
550     connection->command_type    = AVRCP_CTYPE_RESPONSE_IMPLEMENTED_STABLE;
551     connection->subunit_type    = AVRCP_SUBUNIT_TYPE_PANEL;
552     connection->subunit_id      = AVRCP_SUBUNIT_ID;
553 
554     connection->cmd_operands[connection->cmd_operands_length++] = pdu_id;
555     // reserved
556     connection->cmd_operands[connection->cmd_operands_length++] = 0;
557     // param length
558     big_endian_store_16(connection->cmd_operands, connection->cmd_operands_length, param_length);
559     connection->cmd_operands_length += 2;
560     return ERROR_CODE_SUCCESS;
561 }
562 
563 static inline uint8_t avrcp_prepare_vendor_dependent_response(uint16_t avrcp_cid, avrcp_connection_t ** out_connection, avrcp_pdu_id_t pdu_id, uint16_t param_length){
564     *out_connection = avrcp_get_connection_for_avrcp_cid_for_role(AVRCP_TARGET, avrcp_cid);
565     if (!*out_connection){
566         log_error("avrcp tartget: could not find a connection.");
567         return ERROR_CODE_UNKNOWN_CONNECTION_IDENTIFIER;
568     }
569     return avrcp_prepare_vendor_dependent_response_for_connection(*out_connection, pdu_id, param_length);
570 }
571 
572 
573 static uint8_t avrcp_target_supported_events(avrcp_connection_t * connection){
574     uint8_t num_events = 0;
575     uint8_t event_id;
576     uint8_t events[(uint8_t) AVRCP_NOTIFICATION_EVENT_LAST_INDEX];
577 
578     for (event_id = (uint8_t) AVRCP_NOTIFICATION_EVENT_FIRST_INDEX; event_id < (uint8_t) AVRCP_NOTIFICATION_EVENT_LAST_INDEX; event_id++){
579         if ((connection->target_supported_notifications & (1<<event_id)) == 0){
580             continue;
581         }
582         events[num_events] = event_id;
583         num_events++;
584     }
585 
586     uint8_t events_size = sizeof(uint8_t) * num_events;
587     uint8_t status = avrcp_prepare_vendor_dependent_response_for_connection(connection, AVRCP_PDU_ID_GET_CAPABILITIES, 2 + events_size);
588     if (status != ERROR_CODE_SUCCESS) return status;
589 
590     connection->cmd_operands[connection->cmd_operands_length++] = AVRCP_CAPABILITY_ID_EVENT;
591     connection->cmd_operands[connection->cmd_operands_length++] = num_events;
592 
593     (void)memcpy(connection->cmd_operands + connection->cmd_operands_length, events, events_size);
594     connection->cmd_operands_length += events_size;
595 
596     connection->state = AVCTP_W2_SEND_RESPONSE;
597     avrcp_request_can_send_now(connection, connection->l2cap_signaling_cid);
598     return ERROR_CODE_SUCCESS;
599 }
600 
601 static uint8_t avrcp_target_supported_companies(avrcp_connection_t * connection){
602     static uint32_t default_companies[] = {
603         0x581900 //BT SIG registered CompanyID
604     };
605 
606     uint8_t  target_supported_companies_num = connection->target_supported_companies_num;
607     const uint32_t *target_supported_companies = connection->target_supported_companies;
608 
609     if (connection->target_supported_companies_num == 0){
610         target_supported_companies_num = 1;
611         target_supported_companies = default_companies;
612     }
613 
614     uint16_t capabilities_size = target_supported_companies_num * 3;
615 
616     uint8_t status = avrcp_prepare_vendor_dependent_response_for_connection(connection, AVRCP_PDU_ID_GET_CAPABILITIES, 2 + capabilities_size);
617     if (status != ERROR_CODE_SUCCESS) return status;
618 
619     connection->cmd_operands[connection->cmd_operands_length++] = AVRCP_CAPABILITY_ID_COMPANY;
620     connection->cmd_operands[connection->cmd_operands_length++] = target_supported_companies_num;
621 
622     uint8_t i;
623     for (i = 0; i < target_supported_companies_num; i++){
624         little_endian_store_24(connection->cmd_operands, connection->cmd_operands_length, target_supported_companies[i]);
625          connection->cmd_operands_length += 3;
626     }
627 
628     connection->state = AVCTP_W2_SEND_RESPONSE;
629     avrcp_request_can_send_now(connection, connection->l2cap_signaling_cid);
630     return ERROR_CODE_SUCCESS;
631 }
632 
633 uint8_t avrcp_target_support_event(uint16_t avrcp_cid, avrcp_notification_event_id_t event_id){
634     avrcp_connection_t * connection = avrcp_get_connection_for_avrcp_cid_for_role(AVRCP_TARGET, avrcp_cid);
635     if (!connection){
636         return ERROR_CODE_UNKNOWN_CONNECTION_IDENTIFIER;
637     }
638 
639     if ((event_id < (uint8_t)AVRCP_NOTIFICATION_EVENT_FIRST_INDEX) || (event_id > (uint8_t)AVRCP_NOTIFICATION_EVENT_LAST_INDEX)){
640         return ERROR_CODE_UNSUPPORTED_FEATURE_OR_PARAMETER_VALUE;
641     }
642 
643     connection->target_supported_notifications |= (1 << (uint8_t)event_id);
644     return ERROR_CODE_SUCCESS;
645 }
646 
647 uint8_t avrcp_target_support_companies(uint16_t avrcp_cid, uint8_t num_companies, const uint32_t *companies){
648     avrcp_connection_t * connection = avrcp_get_connection_for_avrcp_cid_for_role(AVRCP_TARGET, avrcp_cid);
649     if (!connection){
650         return ERROR_CODE_UNKNOWN_CONNECTION_IDENTIFIER;
651     }
652 
653     connection->target_supported_companies_num = num_companies;
654     connection->target_supported_companies     = companies;
655     return ERROR_CODE_SUCCESS;
656 }
657 
658 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){
659     avrcp_connection_t * connection = NULL;
660     uint8_t status = avrcp_prepare_vendor_dependent_response(avrcp_cid, &connection, AVRCP_PDU_ID_GET_PLAY_STATUS, 11);
661     if (status != ERROR_CODE_SUCCESS) return status;
662 
663     big_endian_store_32(connection->cmd_operands, connection->cmd_operands_length, song_length_ms);
664     connection->cmd_operands_length += 4;
665     big_endian_store_32(connection->cmd_operands, connection->cmd_operands_length, song_position_ms);
666     connection->cmd_operands_length += 4;
667     connection->cmd_operands[connection->cmd_operands_length++] = play_status;
668 
669     connection->state = AVCTP_W2_SEND_RESPONSE;
670     avrcp_request_can_send_now(connection, connection->l2cap_signaling_cid);
671     return ERROR_CODE_SUCCESS;
672 }
673 
674 static uint8_t avrcp_target_now_playing_info(avrcp_connection_t * connection){
675     if (connection->state != AVCTP_CONNECTION_OPENED) return ERROR_CODE_COMMAND_DISALLOWED;
676     connection->now_playing_info_response = 1;
677     connection->command_opcode  = AVRCP_CMD_OPCODE_VENDOR_DEPENDENT;
678     connection->command_type    = AVRCP_CTYPE_RESPONSE_IMPLEMENTED_STABLE;
679     connection->subunit_type    = AVRCP_SUBUNIT_TYPE_PANEL;
680     connection->subunit_id      = AVRCP_SUBUNIT_ID;
681 
682     connection->state = AVCTP_W2_SEND_RESPONSE;
683     avrcp_request_can_send_now(connection, connection->l2cap_signaling_cid);
684     return ERROR_CODE_SUCCESS;
685 }
686 
687 static uint8_t avrcp_target_store_media_attr(avrcp_connection_t * connection, avrcp_media_attribute_id_t attr_id, const char * value){
688     int index = attr_id - 1;
689     if (!value) return AVRCP_STATUS_INVALID_PARAMETER;
690     connection->now_playing_info[index].value = (uint8_t*)value;
691     connection->now_playing_info[index].len   = strlen(value);
692     return ERROR_CODE_SUCCESS;
693 }
694 
695 uint8_t avrcp_target_set_playback_status(uint16_t avrcp_cid, avrcp_playback_status_t playback_status){
696     avrcp_connection_t * connection = avrcp_get_connection_for_avrcp_cid_for_role(AVRCP_TARGET, avrcp_cid);
697     if (!connection){
698         return ERROR_CODE_UNKNOWN_CONNECTION_IDENTIFIER;
699     }
700     if (connection->playback_status == playback_status){
701         return ERROR_CODE_SUCCESS;
702     }
703 
704     connection->playback_status = playback_status;
705     if (connection->notifications_enabled & (1 << AVRCP_NOTIFICATION_EVENT_PLAYBACK_STATUS_CHANGED)) {
706         connection->playback_status_changed = 1;
707         avrcp_request_can_send_now(connection, connection->l2cap_signaling_cid);
708     }
709     return ERROR_CODE_SUCCESS;
710 }
711 
712 uint8_t avrcp_target_set_now_playing_info(uint16_t avrcp_cid, const avrcp_track_t * current_track, uint16_t total_tracks){
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 (!current_track){
718         connection->track_selected = 0;
719         connection->playback_status = AVRCP_PLAYBACK_STATUS_ERROR;
720         return ERROR_CODE_COMMAND_DISALLOWED;
721     }
722 
723     (void)memcpy(connection->track_id, current_track->track_id, 8);
724     connection->song_length_ms = current_track->song_length_ms;
725     connection->track_nr = current_track->track_nr;
726     connection->total_tracks = total_tracks;
727     avrcp_target_store_media_attr(connection, AVRCP_MEDIA_ATTR_TITLE, current_track->title);
728     avrcp_target_store_media_attr(connection, AVRCP_MEDIA_ATTR_ARTIST, current_track->artist);
729     avrcp_target_store_media_attr(connection, AVRCP_MEDIA_ATTR_ALBUM, current_track->album);
730     avrcp_target_store_media_attr(connection, AVRCP_MEDIA_ATTR_GENRE, current_track->genre);
731     connection->track_selected = 1;
732 
733     if (connection->notifications_enabled & (1 << AVRCP_NOTIFICATION_EVENT_TRACK_CHANGED)) {
734         connection->track_changed = 1;
735         avrcp_request_can_send_now(connection, connection->l2cap_signaling_cid);
736     }
737     return ERROR_CODE_SUCCESS;
738 }
739 
740 uint8_t avrcp_target_track_changed(uint16_t avrcp_cid, uint8_t * track_id){
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 (!track_id){
746         return ERROR_CODE_UNSUPPORTED_FEATURE_OR_PARAMETER_VALUE;
747     }
748 
749     (void)memcpy(connection->track_id, track_id, 8);
750     if (connection->notifications_enabled & (1 << AVRCP_NOTIFICATION_EVENT_TRACK_CHANGED)) {
751         connection->track_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_playing_content_changed(uint16_t avrcp_cid){
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 (connection->notifications_enabled & (1 << AVRCP_NOTIFICATION_EVENT_NOW_PLAYING_CONTENT_CHANGED)) {
763         connection->playing_content_changed = 1;
764         avrcp_request_can_send_now(connection, connection->l2cap_signaling_cid);
765     }
766     return ERROR_CODE_SUCCESS;
767 }
768 
769 uint8_t avrcp_target_addressed_player_changed(uint16_t avrcp_cid, uint16_t player_id, uint16_t uid_counter){
770     avrcp_connection_t * connection = avrcp_get_connection_for_avrcp_cid_for_role(AVRCP_TARGET, avrcp_cid);
771     if (!connection){
772         return ERROR_CODE_UNKNOWN_CONNECTION_IDENTIFIER;
773     }
774 
775     if (connection->addressed_player_id == player_id){
776         return ERROR_CODE_SUCCESS;
777     }
778 
779     connection->uid_counter = uid_counter;
780     connection->addressed_player_id = player_id;
781 
782     if (connection->notifications_enabled & (1 << AVRCP_NOTIFICATION_EVENT_ADDRESSED_PLAYER_CHANGED)) {
783         connection->addressed_player_changed = 1;
784         avrcp_request_can_send_now(connection, connection->l2cap_signaling_cid);
785     }
786     return ERROR_CODE_SUCCESS;
787 }
788 
789 uint8_t avrcp_target_battery_status_changed(uint16_t avrcp_cid, avrcp_battery_status_t battery_status){
790     avrcp_connection_t * connection = avrcp_get_connection_for_avrcp_cid_for_role(AVRCP_TARGET, avrcp_cid);
791     if (!connection){
792         return ERROR_CODE_UNKNOWN_CONNECTION_IDENTIFIER;
793     }
794     if (connection->battery_status == battery_status){
795         return ERROR_CODE_SUCCESS;
796     }
797 
798     connection->battery_status = battery_status;
799 
800     if (connection->notifications_enabled & (1 << AVRCP_NOTIFICATION_EVENT_BATT_STATUS_CHANGED)) {
801         connection->battery_status_changed = 1;
802         avrcp_request_can_send_now(connection, connection->l2cap_signaling_cid);
803     }
804     return ERROR_CODE_SUCCESS;
805 }
806 
807 uint8_t avrcp_target_adjust_absolute_volume(uint16_t avrcp_cid, uint8_t absolute_volume){
808     avrcp_connection_t * connection = avrcp_get_connection_for_avrcp_cid_for_role(AVRCP_TARGET, avrcp_cid);
809     if (!connection){
810         return ERROR_CODE_UNKNOWN_CONNECTION_IDENTIFIER;
811     }
812 
813     connection->absolute_volume = absolute_volume;
814     return ERROR_CODE_SUCCESS;
815 }
816 
817 uint8_t avrcp_target_volume_changed(uint16_t avrcp_cid, uint8_t absolute_volume){
818     avrcp_connection_t * connection = avrcp_get_connection_for_avrcp_cid_for_role(AVRCP_TARGET, avrcp_cid);
819     if (!connection){
820         return ERROR_CODE_UNKNOWN_CONNECTION_IDENTIFIER;
821     }
822     if (connection->absolute_volume == absolute_volume){
823         return ERROR_CODE_SUCCESS;
824     }
825 
826     connection->absolute_volume = absolute_volume;
827 
828     if (connection->notifications_enabled & (1 << AVRCP_NOTIFICATION_EVENT_VOLUME_CHANGED )) {
829         connection->notify_absolute_volume_changed = 1;
830         avrcp_request_can_send_now(connection, connection->l2cap_signaling_cid);
831     }
832     return ERROR_CODE_SUCCESS;
833 }
834 
835 static void avrcp_target_set_transaction_label_for_notification(avrcp_connection_t * connection, avrcp_notification_event_id_t notification, uint8_t transaction_label){
836     if (notification > AVRCP_NOTIFICATION_EVENT_MAX_VALUE) return;
837     connection->notifications_transaction_label[notification] = transaction_label;
838 }
839 
840 static uint8_t avrcp_target_get_transaction_label_for_notification(avrcp_connection_t * connection, avrcp_notification_event_id_t notification){
841     if (notification > AVRCP_NOTIFICATION_EVENT_MAX_VALUE) return 0;
842     return connection->notifications_transaction_label[notification];
843 }
844 
845 static bool avcrp_operation_id_is_valid(avrcp_operation_id_t operation_id){
846     if (operation_id < AVRCP_OPERATION_ID_RESERVED_1) return true;
847 
848     if (operation_id < AVRCP_OPERATION_ID_0) return false;
849     if (operation_id < AVRCP_OPERATION_ID_RESERVED_2) return true;
850 
851     if (operation_id < AVRCP_OPERATION_ID_CHANNEL_UP) return false;
852     if (operation_id < AVRCP_OPERATION_ID_RESERVED_3) return true;
853 
854     if (operation_id < AVRCP_OPERATION_ID_CHANNEL_UP) return false;
855     if (operation_id < AVRCP_OPERATION_ID_RESERVED_3) return true;
856 
857     if (operation_id < AVRCP_OPERATION_ID_SKIP) return false;
858     if (operation_id == AVRCP_OPERATION_ID_SKIP) return true;
859 
860     if (operation_id < AVRCP_OPERATION_ID_POWER) return false;
861     if (operation_id < AVRCP_OPERATION_ID_RESERVED_4) return true;
862 
863     if (operation_id < AVRCP_OPERATION_ID_ANGLE) return false;
864     if (operation_id < AVRCP_OPERATION_ID_RESERVED_5) return true;
865 
866     if (operation_id < AVRCP_OPERATION_ID_F1) return false;
867     if (operation_id < AVRCP_OPERATION_ID_RESERVED_6) return true;
868 
869     return false;
870 }
871 
872 static void avrcp_handle_l2cap_data_packet_for_signaling_connection(avrcp_connection_t * connection, uint8_t *packet, uint16_t size){
873 
874     if (size < 6u) return;
875 
876     uint16_t pid = 0;
877     uint8_t transport_header = packet[0];
878     connection->transaction_id = transport_header >> 4;
879 
880     avrcp_packet_type_t packet_type = (avrcp_packet_type_t) ((transport_header & 0x0F) >> 2);
881     switch (packet_type){
882         case AVRCP_SINGLE_PACKET:
883             pid =  big_endian_read_16(packet, 1);
884             break;
885         case AVRCP_START_PACKET:
886             pid =  big_endian_read_16(packet, 2);
887             break;
888         default:
889             break;
890     }
891 
892     switch (packet_type){
893         case AVRCP_SINGLE_PACKET:
894         case AVRCP_START_PACKET:
895             if (pid != BLUETOOTH_SERVICE_CLASS_AV_REMOTE_CONTROL){
896                 log_info("Invalid pid 0x%02x, expected 0x%02x", connection->invalid_pid, BLUETOOTH_SERVICE_CLASS_AV_REMOTE_CONTROL);
897                 connection->reject_transport_header = 1;
898                 connection->invalid_pid = pid;
899                 connection->transport_header = (connection->transaction_id << 4) | (AVRCP_SINGLE_PACKET << 2 ) | (AVRCP_RESPONSE_FRAME << 1) | 1;
900                 connection->state = AVCTP_W2_SEND_RESPONSE;
901                 avrcp_request_can_send_now(connection, connection->l2cap_signaling_cid);
902                 return;
903             }
904             break;
905         default:
906             break;
907     }
908 
909     if (packet_type != AVRCP_SINGLE_PACKET) return;
910 
911     avrcp_subunit_type_t subunit_type = (avrcp_subunit_type_t) (packet[4] >> 3);
912     avrcp_subunit_id_t   subunit_id   = (avrcp_subunit_id_t) (packet[4] & 0x07);
913 
914     avrcp_command_opcode_t opcode = (avrcp_command_opcode_t) avrcp_cmd_opcode(packet,size);
915 
916     int pos = 6;
917     uint16_t length;
918     avrcp_pdu_id_t   pdu_id;
919     connection->cmd_operands_length = 0;
920     uint8_t offset;
921     uint8_t operand;
922     uint16_t event_mask;
923     avrcp_operation_id_t operation_id;
924 
925     switch (opcode){
926         case AVRCP_CMD_OPCODE_UNIT_INFO:
927             avrcp_target_unit_info(connection);
928             break;
929         case AVRCP_CMD_OPCODE_SUBUNIT_INFO:
930             if ((size - pos) < 3) return;
931             // page: packet[pos] >> 4,
932             offset =  4 * (packet[pos]>>4);
933             // extension code (fixed 7) = packet[pos] & 0x0F
934             // 4 bytes paga data, all 0xFF
935             avrcp_target_subunit_info(connection, offset);
936             break;
937 
938         case AVRCP_CMD_OPCODE_PASS_THROUGH:
939             if (size < 8) return;
940             log_info("AVRCP_OPERATION_ID 0x%02x, operands length %d", packet[6], packet[7]);
941             operation_id = (avrcp_operation_id_t) (packet[6] & 0x7f);
942             operand = 0;
943             if ((packet[7] >= 1) && (size >= 9)){
944                 operand = packet[8];
945             }
946 
947             if (avcrp_operation_id_is_valid(operation_id)){
948                 bool button_pressed = (packet[6] & 0x80) == 0;
949 
950                 avrcp_target_operation_accepted(connection->avrcp_cid, (avrcp_operation_id_t) packet[6], packet[7], operand);
951                 avrcp_target_emit_operation(avrcp_target_context.avrcp_callback, connection->avrcp_cid,
952                                                 operation_id, button_pressed, packet[7], operand);
953             } else {
954                 avrcp_target_operation_not_implemented(connection->avrcp_cid, (avrcp_operation_id_t) packet[6], packet[7], operand);
955             }
956             break;
957 
958 
959         case AVRCP_CMD_OPCODE_VENDOR_DEPENDENT:
960 
961             if (size < 13) return;
962 
963             // pos = 6 - company id
964             (void)memcpy(connection->cmd_operands, &packet[pos], 3);
965             connection->cmd_operands_length = 3;
966             pos += 3;
967             // pos = 9
968             pdu_id = (avrcp_pdu_id_t) packet[pos++];
969             // 1 - reserved
970             pos++;
971             // 2-3 param length,
972             length = big_endian_read_16(packet, pos);
973             pos += 2;
974             // pos = 13
975             switch (pdu_id){
976                 case AVRCP_PDU_ID_SET_ADDRESSED_PLAYER:{
977                     if ((pos + 2) > size) return;
978                     bool ok = length == 4;
979                     if (avrcp_target_context.set_addressed_player_callback != NULL){
980                         uint16_t player_id = big_endian_read_16(packet, pos);
981                         ok = avrcp_target_context.set_addressed_player_callback(player_id);
982                     }
983                     if (ok){
984                         avrcp_target_response_accept(connection, subunit_type, subunit_id, opcode, pdu_id, AVRCP_STATUS_SUCCESS);
985                     } else {
986                         avrcp_target_response_reject(connection, subunit_type, subunit_id, opcode, pdu_id, AVRCP_STATUS_INVALID_PLAYER_ID);
987                     }
988                     break;
989                 }
990                 case AVRCP_PDU_ID_GET_CAPABILITIES:{
991                     avrcp_capability_id_t capability_id = (avrcp_capability_id_t) packet[pos];
992                     switch (capability_id){
993                         case AVRCP_CAPABILITY_ID_EVENT:
994                              avrcp_target_supported_events(connection);
995                             break;
996                         case AVRCP_CAPABILITY_ID_COMPANY:
997                             avrcp_target_supported_companies(connection);
998                             break;
999                         default:
1000                             avrcp_target_response_reject(connection, subunit_type, subunit_id, opcode, pdu_id, AVRCP_STATUS_INVALID_PARAMETER);
1001                             break;
1002                     }
1003                     break;
1004                 }
1005                 case AVRCP_PDU_ID_GET_PLAY_STATUS:
1006                     avrcp_target_emit_respond_vendor_dependent_query(avrcp_target_context.avrcp_callback, connection->avrcp_cid, AVRCP_SUBEVENT_PLAY_STATUS_QUERY);
1007                     break;
1008                 case AVRCP_PDU_ID_REQUEST_ABORT_CONTINUING_RESPONSE:
1009                     if ((pos + 1) > size) return;
1010                     connection->cmd_operands[0] = packet[pos];
1011                     connection->abort_continue_response = 1;
1012                     avrcp_request_can_send_now(connection, connection->l2cap_signaling_cid);
1013                     break;
1014                 case AVRCP_PDU_ID_REQUEST_CONTINUING_RESPONSE:
1015                     if ((pos + 1) > size) return;
1016                     if (packet[pos] != AVRCP_PDU_ID_GET_ELEMENT_ATTRIBUTES){
1017                         avrcp_target_response_reject(connection, subunit_type, subunit_id, opcode, pdu_id, AVRCP_STATUS_INVALID_COMMAND);
1018                         return;
1019                     }
1020                     connection->now_playing_info_response = 1;
1021                     avrcp_request_can_send_now(connection, connection->l2cap_signaling_cid);
1022                     break;
1023                 case AVRCP_PDU_ID_GET_ELEMENT_ATTRIBUTES:{
1024                     if ((pos + 9) > size) return;
1025                     uint8_t play_identifier[8];
1026                     memset(play_identifier, 0, 8);
1027                     if (memcmp(&packet[pos], play_identifier, 8) != 0) {
1028                         avrcp_target_response_reject(connection, subunit_type, subunit_id, opcode, pdu_id, AVRCP_STATUS_INVALID_PARAMETER);
1029                         return;
1030                     }
1031                     pos += 8;
1032                     uint8_t attribute_count = packet[pos++];
1033                     connection->next_attr_id = AVRCP_MEDIA_ATTR_NONE;
1034                     if (!attribute_count){
1035                         connection->now_playing_info_attr_bitmap = 0xFE;
1036                     } else {
1037                         int i;
1038                         connection->now_playing_info_attr_bitmap = 0;
1039                         if ((pos + attribute_count * 2) > size) return;
1040                         for (i=0; i < attribute_count; i++){
1041                             uint16_t attr_id = big_endian_read_16(packet, pos);
1042                             pos += 2;
1043                             connection->now_playing_info_attr_bitmap |= (1 << attr_id);
1044                         }
1045                     }
1046                     log_info("now_playing_info_attr_bitmap 0x%02x", connection->now_playing_info_attr_bitmap);
1047                     avrcp_target_now_playing_info(connection);
1048                     break;
1049                 }
1050                 case AVRCP_PDU_ID_REGISTER_NOTIFICATION:{
1051                     if ((pos + 1) > size) return;
1052                     avrcp_notification_event_id_t event_id = (avrcp_notification_event_id_t) packet[pos];
1053 
1054                     avrcp_target_set_transaction_label_for_notification(connection, event_id, connection->transaction_id);
1055 
1056                     if (event_id < AVRCP_NOTIFICATION_EVENT_PLAYBACK_STATUS_CHANGED ||
1057                         event_id > AVRCP_NOTIFICATION_EVENT_MAX_VALUE){
1058                         avrcp_target_response_reject(connection, subunit_type, subunit_id, opcode, pdu_id, AVRCP_STATUS_INVALID_PARAMETER);
1059                         return;
1060                     }
1061 
1062                     switch (event_id){
1063                         case AVRCP_NOTIFICATION_EVENT_AVAILABLE_PLAYERS_CHANGED:
1064                         case AVRCP_NOTIFICATION_EVENT_PLAYER_APPLICATION_SETTING_CHANGED:
1065                         case AVRCP_NOTIFICATION_EVENT_UIDS_CHANGED:
1066                         case AVRCP_NOTIFICATION_EVENT_TRACK_REACHED_END:
1067                         case AVRCP_NOTIFICATION_EVENT_TRACK_REACHED_START:
1068                         case AVRCP_NOTIFICATION_EVENT_PLAYBACK_POS_CHANGED:
1069                         case AVRCP_NOTIFICATION_EVENT_SYSTEM_STATUS_CHANGED:
1070                         case AVRCP_NOTIFICATION_EVENT_MAX_VALUE:
1071                             avrcp_target_response_not_implemented(connection, subunit_type, subunit_id, opcode, pdu_id, event_id);
1072                             return;
1073                         default:
1074                             break;
1075                     }
1076 
1077                     event_mask = (1 << event_id);
1078                     connection->notifications_enabled |= event_mask;
1079                     avrcp_target_response_setup(connection, AVRCP_CTYPE_RESPONSE_INTERIM, subunit_type, subunit_id, opcode);
1080 
1081                     switch (event_id){
1082                         case AVRCP_NOTIFICATION_EVENT_TRACK_CHANGED:
1083                             if (connection->track_selected){
1084                                 avrcp_target_response_vendor_dependent_interim(connection, pdu_id, event_id, AVRCP_NOTIFICATION_TRACK_SELECTED, 8);
1085                             } else {
1086                                 avrcp_target_response_vendor_dependent_interim(connection, pdu_id, event_id, AVRCP_NOTIFICATION_TRACK_NOT_SELECTED, 8);
1087                             }
1088                             break;
1089                         case AVRCP_NOTIFICATION_EVENT_PLAYBACK_STATUS_CHANGED:
1090                             avrcp_target_response_vendor_dependent_interim(connection, pdu_id, event_id, (const uint8_t *)&connection->playback_status, 1);
1091                             break;
1092                         case AVRCP_NOTIFICATION_EVENT_NOW_PLAYING_CONTENT_CHANGED:
1093                             avrcp_target_response_vendor_dependent_interim(connection, pdu_id, event_id, NULL, 0);
1094                             break;
1095                         case AVRCP_NOTIFICATION_EVENT_VOLUME_CHANGED:
1096                             avrcp_target_response_vendor_dependent_interim(connection, pdu_id, event_id, (const uint8_t *)&connection->absolute_volume, 1);
1097                             break;
1098                         case AVRCP_NOTIFICATION_EVENT_BATT_STATUS_CHANGED:
1099                             avrcp_target_response_vendor_dependent_interim(connection, pdu_id, event_id, (const uint8_t *)&connection->battery_status, 1);
1100                             break;
1101                         case AVRCP_NOTIFICATION_EVENT_ADDRESSED_PLAYER_CHANGED:
1102                             avrcp_target_response_addressed_player_changed_interim(connection, subunit_type, subunit_id, opcode, pdu_id);
1103                             return;
1104                         default:
1105                             btstack_assert(false);
1106                             return;
1107                     }
1108                     break;
1109                 }
1110                 case AVRCP_PDU_ID_SET_ABSOLUTE_VOLUME: {
1111                     if ( (length != 1) || ((pos + 1) > size)){
1112                         avrcp_target_response_reject(connection, subunit_type, subunit_id, opcode, pdu_id, AVRCP_STATUS_INVALID_COMMAND);
1113                         break;
1114                     }
1115 
1116                     uint8_t absolute_volume = packet[pos];
1117                     if (absolute_volume < 0x80){
1118                         connection->absolute_volume = absolute_volume;
1119                     }
1120                     avrcp_target_emit_volume_changed(avrcp_target_context.avrcp_callback, connection->avrcp_cid, connection->absolute_volume);
1121                     avrcp_target_response_accept(connection, subunit_type, subunit_id, opcode, pdu_id, connection->absolute_volume);
1122                     break;
1123                 }
1124                 default:
1125                     log_info("AVRCP target: unhandled pdu id 0x%02x", pdu_id);
1126                     avrcp_target_response_reject(connection, subunit_type, subunit_id, opcode, pdu_id, AVRCP_STATUS_INVALID_COMMAND);
1127                     break;
1128             }
1129             break;
1130         default:
1131             log_info("AVRCP target: opcode 0x%02x not implemented", avrcp_cmd_opcode(packet,size));
1132             break;
1133     }
1134 }
1135 
1136 static int avrcp_target_send_notification(uint16_t cid, avrcp_connection_t * connection, avrcp_notification_event_id_t notification_id, uint8_t * value, uint16_t value_len){
1137     if (!connection){
1138         return ERROR_CODE_UNKNOWN_CONNECTION_IDENTIFIER;
1139     }
1140 
1141     btstack_assert((value_len == 0) || (value != NULL));
1142 
1143     connection->command_opcode  = AVRCP_CMD_OPCODE_VENDOR_DEPENDENT;
1144     connection->command_type    = AVRCP_CTYPE_RESPONSE_CHANGED_STABLE;
1145     connection->subunit_type    = AVRCP_SUBUNIT_TYPE_PANEL;
1146     connection->subunit_id      = AVRCP_SUBUNIT_ID;
1147     connection->transaction_id = avrcp_target_get_transaction_label_for_notification(connection, notification_id);
1148 
1149     uint16_t pos = 0;
1150     l2cap_reserve_packet_buffer();
1151     uint8_t * packet = l2cap_get_outgoing_buffer();
1152 
1153     // value <= 8 ==> pdu <= 22 < L2CAP Default MTU
1154     btstack_assert((14 + value_len) <= l2cap_get_remote_mtu_for_local_cid(connection->l2cap_signaling_cid));
1155 
1156     connection->packet_type = AVRCP_SINGLE_PACKET;
1157     packet[pos++] = (connection->transaction_id << 4) | (connection->packet_type << 2) | (AVRCP_RESPONSE_FRAME << 1) | 0;
1158     // Profile IDentifier (PID)
1159     packet[pos++] = BLUETOOTH_SERVICE_CLASS_AV_REMOTE_CONTROL >> 8;
1160     packet[pos++] = BLUETOOTH_SERVICE_CLASS_AV_REMOTE_CONTROL & 0x00FF;
1161 
1162     // command_type
1163     packet[pos++] = connection->command_type;
1164     // subunit_type | subunit ID
1165     packet[pos++] = (connection->subunit_type << 3) | connection->subunit_id;
1166     // opcode
1167     packet[pos++] = (uint8_t)connection->command_opcode;
1168 
1169     // company id is 3 bytes long
1170     big_endian_store_24(packet, pos, BT_SIG_COMPANY_ID);
1171     pos += 3;
1172 
1173     packet[pos++] = AVRCP_PDU_ID_REGISTER_NOTIFICATION;
1174     packet[pos++] = 0;
1175 
1176     big_endian_store_16(packet, pos, 1 + value_len);
1177     pos += 2;
1178     packet[pos++] = notification_id;
1179     if (value_len > 0){
1180         (void)memcpy(packet + pos, value, value_len);
1181         pos += value_len;
1182     }
1183 
1184     return l2cap_send_prepared(cid, pos);
1185 }
1186 
1187 static void avrcp_target_reset_notification(avrcp_connection_t * connection, avrcp_notification_event_id_t notification_id){
1188     if (!connection){
1189         log_error("avrcp tartget: could not find a connection.");
1190         return;
1191     }
1192     connection->notifications_enabled &= ~(1 << notification_id);
1193     connection->command_opcode  = AVRCP_CMD_OPCODE_VENDOR_DEPENDENT;
1194     avrcp_target_set_transaction_label_for_notification(connection, notification_id, 0);
1195 }
1196 
1197 static void avrcp_target_packet_handler(uint8_t packet_type, uint16_t channel, uint8_t *packet, uint16_t size){
1198     avrcp_connection_t * connection;
1199     switch (packet_type) {
1200         case L2CAP_DATA_PACKET:
1201             connection = avrcp_get_connection_for_l2cap_signaling_cid_for_role(AVRCP_TARGET, channel);
1202             avrcp_handle_l2cap_data_packet_for_signaling_connection(connection, packet, size);
1203             break;
1204         case HCI_EVENT_PACKET:
1205             switch (hci_event_packet_get_type(packet)){
1206                 case L2CAP_EVENT_CAN_SEND_NOW:{
1207                     connection = avrcp_get_connection_for_l2cap_signaling_cid_for_role(AVRCP_TARGET, channel);
1208 
1209                     if (connection->accept_response){
1210                         connection->accept_response = 0;
1211                         avrcp_target_send_response(connection->l2cap_signaling_cid, connection);
1212                         avrcp_request_can_send_now(connection, connection->l2cap_signaling_cid);
1213                         return;
1214                     }
1215 
1216                     if (connection->abort_continue_response){
1217                         connection->abort_continue_response = 0;
1218                         connection->now_playing_info_response = 0;
1219                         avrcp_target_abort_continue_response(connection->l2cap_signaling_cid, connection);
1220                         return;
1221                     }
1222 
1223                     if (connection->now_playing_info_response){
1224                         connection->now_playing_info_response = 0;
1225                         avrcp_target_send_now_playing_info(connection->l2cap_signaling_cid, connection);
1226                         return;
1227                     }
1228 
1229                     if (connection->track_changed){
1230                         connection->track_changed = 0;
1231                         avrcp_target_send_notification(connection->l2cap_signaling_cid, connection, AVRCP_NOTIFICATION_EVENT_TRACK_CHANGED, connection->track_id, 8);
1232                         avrcp_target_reset_notification(connection, AVRCP_NOTIFICATION_EVENT_TRACK_CHANGED);
1233                         avrcp_request_can_send_now(connection, connection->l2cap_signaling_cid);
1234                         return;
1235                     }
1236 
1237                     if (connection->playback_status_changed){
1238                         connection->playback_status_changed = 0;
1239                         uint8_t playback_status = (uint8_t) connection->playback_status;
1240                         avrcp_target_send_notification(connection->l2cap_signaling_cid, connection, AVRCP_NOTIFICATION_EVENT_PLAYBACK_STATUS_CHANGED, &playback_status, 1);
1241                         avrcp_target_reset_notification(connection, AVRCP_NOTIFICATION_EVENT_PLAYBACK_STATUS_CHANGED);
1242                         avrcp_request_can_send_now(connection, connection->l2cap_signaling_cid);
1243                         return;
1244                     }
1245 
1246                     if (connection->playing_content_changed){
1247                         connection->playing_content_changed = 0;
1248                         avrcp_target_send_notification(connection->l2cap_signaling_cid, connection, AVRCP_NOTIFICATION_EVENT_NOW_PLAYING_CONTENT_CHANGED, NULL, 0);
1249                         avrcp_target_reset_notification(connection, AVRCP_NOTIFICATION_EVENT_NOW_PLAYING_CONTENT_CHANGED);
1250                         avrcp_request_can_send_now(connection, connection->l2cap_signaling_cid);
1251                         return;
1252                     }
1253 
1254                     if (connection->battery_status_changed){
1255                         connection->battery_status_changed = 0;
1256                         avrcp_target_send_notification(connection->l2cap_signaling_cid, connection, AVRCP_NOTIFICATION_EVENT_BATT_STATUS_CHANGED, (uint8_t *)&connection->battery_status, 1);
1257                         avrcp_target_reset_notification(connection, AVRCP_NOTIFICATION_EVENT_BATT_STATUS_CHANGED);
1258                         avrcp_request_can_send_now(connection, connection->l2cap_signaling_cid);
1259                         return;
1260                     }
1261 
1262                     if (connection->notify_absolute_volume_changed){
1263                         connection->notify_absolute_volume_changed = 0;
1264                         avrcp_target_send_notification(connection->l2cap_signaling_cid, connection, AVRCP_NOTIFICATION_EVENT_VOLUME_CHANGED, &connection->absolute_volume, 1);
1265                         avrcp_target_reset_notification(connection, AVRCP_NOTIFICATION_EVENT_VOLUME_CHANGED);
1266                         avrcp_request_can_send_now(connection, connection->l2cap_signaling_cid);
1267                         return;
1268                     }
1269 
1270                     if (connection->addressed_player_changed){
1271                         connection->addressed_player_changed = 0;
1272                         uint8_t buffer[4];
1273                         big_endian_store_16(buffer, 0, connection->addressed_player_id);
1274                         big_endian_store_16(buffer, 2, connection->uid_counter);
1275                         avrcp_target_send_notification(connection->l2cap_signaling_cid, connection, AVRCP_NOTIFICATION_EVENT_ADDRESSED_PLAYER_CHANGED, buffer, 4);
1276                         avrcp_target_reset_notification(connection, AVRCP_NOTIFICATION_EVENT_ADDRESSED_PLAYER_CHANGED);
1277                         avrcp_request_can_send_now(connection, connection->l2cap_signaling_cid);
1278                         return;
1279                     }
1280 
1281                     if (connection->reject_transport_header){
1282                         connection->state = AVCTP_CONNECTION_OPENED;
1283                         connection->reject_transport_header = 0;
1284                         l2cap_reserve_packet_buffer();
1285                         uint8_t * out_buffer = l2cap_get_outgoing_buffer();
1286                         out_buffer[0] = connection->transport_header;
1287                         big_endian_store_16(out_buffer, 1, connection->invalid_pid);
1288                         l2cap_send_prepared(connection->l2cap_signaling_cid, 3);
1289                         avrcp_request_can_send_now(connection, connection->l2cap_signaling_cid);
1290                         return;
1291                     }
1292 
1293                     switch (connection->state){
1294                         case AVCTP_W2_SEND_RESPONSE:
1295                             connection->state = AVCTP_CONNECTION_OPENED;
1296                             avrcp_target_send_response(connection->l2cap_signaling_cid, connection);
1297                             avrcp_request_can_send_now(connection, connection->l2cap_signaling_cid);
1298                             return;
1299                         default:
1300                             break;
1301                     }
1302 
1303                     break;
1304             }
1305             default:
1306                 break;
1307         }
1308         default:
1309             break;
1310     }
1311 }
1312 
1313 void avrcp_target_init(void){
1314     avrcp_target_context.role = AVRCP_TARGET;
1315     avrcp_target_context.packet_handler = avrcp_target_packet_handler;
1316     avrcp_register_target_packet_handler(&avrcp_target_packet_handler);
1317 }
1318 
1319 void avrcp_target_deinit(void){
1320     memset(&avrcp_target_context, 0, sizeof(avrcp_context_t));
1321 }
1322 
1323 void avrcp_target_register_packet_handler(btstack_packet_handler_t callback){
1324     btstack_assert(callback != NULL);
1325     avrcp_target_context.avrcp_callback = callback;
1326 }
1327 
1328 void avrcp_target_register_set_addressed_player_handler(bool (*callback)(uint16_t player_id)){
1329     btstack_assert(callback != NULL);
1330     avrcp_target_context.set_addressed_player_callback = callback;
1331 }
1332 
1333 
1334