xref: /btstack/src/classic/avrcp_target.c (revision e9c5f44ee8add45f6cd4be8b6faa9e09a2804fcc)
1 /*
2  * Copyright (C) 2016 BlueKitchen GmbH
3  *
4  * Redistribution and use in source and binary forms, with or without
5  * modification, are permitted provided that the following conditions
6  * are met:
7  *
8  * 1. Redistributions of source code must retain the above copyright
9  *    notice, this list of conditions and the following disclaimer.
10  * 2. Redistributions in binary form must reproduce the above copyright
11  *    notice, this list of conditions and the following disclaimer in the
12  *    documentation and/or other materials provided with the distribution.
13  * 3. Neither the name of the copyright holders nor the names of
14  *    contributors may be used to endorse or promote products derived
15  *    from this software without specific prior written permission.
16  * 4. Any redistribution, use, or modification is done solely for
17  *    personal benefit and not for any commercial purpose or for
18  *    monetary gain.
19  *
20  * THIS SOFTWARE IS PROVIDED BY BLUEKITCHEN GMBH AND CONTRIBUTORS
21  * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
22  * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
23  * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL MATTHIAS
24  * RINGWALD OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
25  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
26  * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
27  * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
28  * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
29  * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF
30  * THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
31  * SUCH DAMAGE.
32  *
33  * Please inquire about commercial licensing options at
34  * [email protected]
35  *
36  */
37 
38 #define __BTSTACK_FILE__ "avrcp_target.c"
39 
40 #include <stdint.h>
41 #include <stdio.h>
42 #include <stdlib.h>
43 #include <string.h>
44 #include <inttypes.h>
45 
46 #include "btstack.h"
47 #include "classic/avrcp.h"
48 
49 #define AVRCP_ATTR_HEADER_LEN  8
50 
51 static const uint8_t AVRCP_NOTIFICATION_TRACK_SELECTED[] = {0,0,0,0,0,0,0,0};
52 static const uint8_t AVRCP_NOTIFICATION_TRACK_NOT_SELECTED[] = {0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF};
53 
54 avrcp_context_t avrcp_target_context;
55 
56 static int avrcp_target_supports_browsing(uint16_t target_supported_features){
57     return target_supported_features & (1 << AVRCP_TARGET_SUPPORTED_FEATURE_BROWSING);
58 }
59 
60 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){
61     avrcp_create_sdp_record(0, service, service_record_handle, avrcp_target_supports_browsing(supported_features), supported_features, service_name, service_provider_name);
62 }
63 
64 static void avrcp_target_emit_operation(btstack_packet_handler_t callback, uint16_t avrcp_cid, avrcp_operation_id_t operation_id, uint8_t operands_length, uint8_t operand){
65     if (!callback) return;
66     uint8_t event[8];
67     int pos = 0;
68     event[pos++] = HCI_EVENT_AVRCP_META;
69     event[pos++] = sizeof(event) - 2;
70     event[pos++] = AVRCP_SUBEVENT_OPERATION;
71     little_endian_store_16(event, pos, avrcp_cid);
72     pos += 2;
73     event[pos++] = operation_id;
74     event[pos++] = operands_length;
75     event[pos++] = operand;
76     (*callback)(HCI_EVENT_PACKET, 0, event, sizeof(event));
77 }
78 
79 static void avrcp_target_emit_respond_vendor_dependent_query(btstack_packet_handler_t callback, uint16_t avrcp_cid, uint8_t subevent_id){
80     if (!callback) return;
81     uint8_t event[5];
82     int pos = 0;
83     event[pos++] = HCI_EVENT_AVRCP_META;
84     event[pos++] = sizeof(event) - 2;
85     event[pos++] = subevent_id;
86     little_endian_store_16(event, pos, avrcp_cid);
87     (*callback)(HCI_EVENT_PACKET, 0, event, sizeof(event));
88 }
89 
90 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){
91     if ((attr_id < 1) || (attr_id > AVRCP_MEDIA_ATTR_COUNT)) return 0;
92     uint16_t attr_value_length = sprintf((char *)(packet+pos+8), "%0" PRIu32, value);
93     big_endian_store_32(packet, pos, attr_id);
94     pos += 4;
95     big_endian_store_16(packet, pos, RFC2978_CHARSET_MIB_UTF8);
96     pos += 2;
97     big_endian_store_16(packet, pos, attr_value_length);
98     pos += 2;
99     return 8 + attr_value_length;
100 }
101 
102 static uint16_t avrcp_target_pack_single_element_attribute_string(uint8_t * packet, uint16_t pos, rfc2978_charset_mib_enumid_t mib_enumid, avrcp_media_attribute_id_t attr_id, uint8_t * attr_value, uint16_t attr_value_to_copy, uint16_t attr_value_size, uint8_t header){
103     if (attr_value_size == 0) return 0;
104     if ((attr_id < 1) || (attr_id > AVRCP_MEDIA_ATTR_COUNT)) return 0;
105     if (header){
106         big_endian_store_32(packet, pos, attr_id);
107         pos += 4;
108         big_endian_store_16(packet, pos, mib_enumid);
109         pos += 2;
110         big_endian_store_16(packet, pos, attr_value_size);
111         pos += 2;
112     }
113     memcpy(packet+pos, attr_value, attr_value_to_copy);
114     pos += attr_value_size;
115     return header * 8 + attr_value_size;
116 }
117 
118 static int avrcp_target_abort_continue_response(uint16_t cid, avrcp_connection_t * connection){
119     uint16_t pos = 0;
120     l2cap_reserve_packet_buffer();
121     uint8_t * packet = l2cap_get_outgoing_buffer();
122 
123     connection->command_opcode  = AVRCP_CMD_OPCODE_VENDOR_DEPENDENT;
124     connection->command_type    = AVRCP_CTYPE_RESPONSE_ACCEPTED;
125     connection->subunit_type    = AVRCP_SUBUNIT_TYPE_PANEL;
126     connection->subunit_id      = AVRCP_SUBUNIT_ID;
127 
128     packet[pos++] = (connection->transaction_label << 4) | (AVRCP_SINGLE_PACKET << 2) | (AVRCP_RESPONSE_FRAME << 1) | 0;
129     // Profile IDentifier (PID)
130     packet[pos++] = BLUETOOTH_SERVICE_CLASS_AV_REMOTE_CONTROL >> 8;
131     packet[pos++] = BLUETOOTH_SERVICE_CLASS_AV_REMOTE_CONTROL & 0x00FF;
132 
133     // command_type
134     packet[pos++] = connection->command_type;
135     // subunit_type | subunit ID
136     packet[pos++] = (connection->subunit_type << 3) | connection->subunit_id;
137     // opcode
138     packet[pos++] = (uint8_t)connection->command_opcode;
139 
140     // company id is 3 bytes long
141     big_endian_store_24(packet, pos, BT_SIG_COMPANY_ID);
142     pos += 3;
143 
144     packet[pos++] = AVRCP_PDU_ID_REQUEST_ABORT_CONTINUING_RESPONSE;
145 
146     // reserve byte for packet type
147     packet[pos++] = AVRCP_SINGLE_PACKET;
148     big_endian_store_16(packet, pos, 0);
149     pos += 2;
150     return l2cap_send_prepared(cid, pos);
151 }
152 
153 static int avrcp_target_send_now_playing_info(uint16_t cid, avrcp_connection_t * connection){
154     uint16_t pos = 0;
155     l2cap_reserve_packet_buffer();
156     uint8_t * packet = l2cap_get_outgoing_buffer();
157     uint16_t  size   = l2cap_get_remote_mtu_for_local_cid(connection->l2cap_signaling_cid);
158 
159     packet[pos++] = (connection->transaction_label << 4) | (AVRCP_SINGLE_PACKET << 2) | (AVRCP_RESPONSE_FRAME << 1) | 0;
160     // Profile IDentifier (PID)
161     packet[pos++] = BLUETOOTH_SERVICE_CLASS_AV_REMOTE_CONTROL >> 8;
162     packet[pos++] = BLUETOOTH_SERVICE_CLASS_AV_REMOTE_CONTROL & 0x00FF;
163 
164     // command_type
165     packet[pos++] = connection->command_type;
166     // subunit_type | subunit ID
167     packet[pos++] = (connection->subunit_type << 3) | connection->subunit_id;
168     // opcode
169     packet[pos++] = (uint8_t)connection->command_opcode;
170 
171     // company id is 3 bytes long
172     big_endian_store_24(packet, pos, BT_SIG_COMPANY_ID);
173     pos += 3;
174 
175     packet[pos++] = AVRCP_PDU_ID_GET_ELEMENT_ATTRIBUTES;
176 
177     // reserve byte for packet type
178     uint8_t pos_packet_type = pos;
179     pos++;
180 
181     uint16_t playing_info_buffer_len_position = pos;
182     pos += 2;
183     // printf("connection->next_attr_id %d \n", connection->next_attr_id);
184     if (connection->next_attr_id == AVRCP_MEDIA_ATTR_NONE){
185         packet[pos_packet_type] = AVRCP_SINGLE_PACKET;
186         connection->packet_type = AVRCP_SINGLE_PACKET;
187         packet[pos++] = count_set_bits_uint32(connection->now_playing_info_attr_bitmap);
188         connection->next_attr_id = AVRCP_MEDIA_ATTR_ALL;
189     }
190     // printf("updated connection->next_attr_id %d, connection->attribute_value_offset %d \n", connection->next_attr_id, connection->attribute_value_offset);
191 
192     uint8_t fragmented = 0;
193     int num_free_bytes = size - pos - 2;
194     uint8_t MAX_NUMBER_ATTR_LEN = 10;
195 
196     while (!fragmented && num_free_bytes > 0 && connection->next_attr_id <= AVRCP_MEDIA_ATTR_SONG_LENGTH_MS){
197         avrcp_media_attribute_id_t attr_id = connection->next_attr_id;
198         int attr_index = attr_id - 1;
199 
200         if (connection->now_playing_info_attr_bitmap & (1 << attr_id)){
201             int num_written_bytes = 0;
202             int num_bytes_to_write = 0;
203             switch (attr_id){
204                 case AVRCP_MEDIA_ATTR_ALL:
205                 case AVRCP_MEDIA_ATTR_NONE:
206                     break;
207                 case AVRCP_MEDIA_ATTR_TRACK:
208                     num_bytes_to_write = AVRCP_ATTR_HEADER_LEN + MAX_NUMBER_ATTR_LEN;
209                     if (num_free_bytes >= num_bytes_to_write){
210                         num_written_bytes = avrcp_target_pack_single_element_attribute_number(packet, pos, attr_id, connection->track_nr);
211                         break;
212                     }
213                     fragmented = 1;
214                     connection->attribute_value_offset = 0;
215                     break;
216                 case AVRCP_MEDIA_ATTR_TOTAL_NUM_ITEMS:
217                     num_bytes_to_write = AVRCP_ATTR_HEADER_LEN + MAX_NUMBER_ATTR_LEN;
218                     if (num_free_bytes >= num_bytes_to_write){
219                         num_written_bytes = avrcp_target_pack_single_element_attribute_number(packet, pos, attr_id, connection->total_tracks);
220                         break;
221                     }
222                     fragmented = 1;
223                     connection->attribute_value_offset = 0;
224                     break;
225                 case AVRCP_MEDIA_ATTR_SONG_LENGTH_MS:
226                     num_bytes_to_write = AVRCP_ATTR_HEADER_LEN + MAX_NUMBER_ATTR_LEN;
227                     if (num_free_bytes >= num_bytes_to_write){
228                         num_written_bytes = avrcp_target_pack_single_element_attribute_number(packet, pos, attr_id, connection->song_length_ms);
229                         break;
230                     }
231                     fragmented = 1;
232                     connection->attribute_value_offset = 0;
233                     break;
234                 default:{
235                     uint8_t   header = (connection->attribute_value_offset == 0);
236                     uint8_t * attr_value =     (uint8_t *) (connection->now_playing_info[attr_index].value + connection->attribute_value_offset);
237                     uint16_t  attr_value_len = connection->now_playing_info[attr_index].len - connection->attribute_value_offset;
238 
239                     num_bytes_to_write = attr_value_len + header * AVRCP_ATTR_HEADER_LEN;
240                     if (num_bytes_to_write <= num_free_bytes){
241                         connection->attribute_value_offset = 0;
242                         num_written_bytes = num_bytes_to_write;
243                         avrcp_target_pack_single_element_attribute_string(packet, pos, RFC2978_CHARSET_MIB_UTF8, attr_id, attr_value, attr_value_len, connection->now_playing_info[attr_index].len, header);
244                         break;
245                     }
246                     fragmented = 1;
247                     num_written_bytes = num_free_bytes;
248                     attr_value_len = num_free_bytes - header * AVRCP_ATTR_HEADER_LEN;
249                     avrcp_target_pack_single_element_attribute_string(packet, pos, RFC2978_CHARSET_MIB_UTF8, attr_id, attr_value, attr_value_len, connection->now_playing_info[attr_index].len, header);
250                     connection->attribute_value_offset += attr_value_len;
251                     break;
252                 }
253             }
254             pos += num_written_bytes;
255             num_free_bytes -= num_written_bytes;
256         }
257         if (!fragmented){
258             // C++ compatible version of connection->next_attr_id++
259             connection->next_attr_id = (avrcp_media_attribute_id_t) (((int) connection->next_attr_id) + 1);
260         }
261     }
262 
263     if (fragmented){
264         switch (connection->packet_type){
265             case AVRCP_SINGLE_PACKET:
266                 connection->packet_type = AVRCP_START_PACKET;
267                 break;
268             default:
269                 connection->packet_type = AVRCP_CONTINUE_PACKET;
270                 break;
271         }
272     } else {
273         if (connection->next_attr_id >= AVRCP_MEDIA_ATTR_SONG_LENGTH_MS){ // DONE
274             if (connection->packet_type != AVRCP_SINGLE_PACKET){
275                 connection->packet_type = AVRCP_END_PACKET;
276             }
277         }
278     }
279     packet[pos_packet_type] = connection->packet_type;
280     // store attr value length
281     big_endian_store_16(packet, playing_info_buffer_len_position, pos - playing_info_buffer_len_position - 2);
282     return l2cap_send_prepared(cid, size);
283 }
284 
285 
286 
287 static int avrcp_target_send_response(uint16_t cid, avrcp_connection_t * connection){
288     int pos = 0;
289     l2cap_reserve_packet_buffer();
290     uint8_t * packet = l2cap_get_outgoing_buffer();
291 
292     // transport header
293     // Transaction label | Packet_type | C/R | IPID (1 == invalid profile identifier)
294 
295     // TODO: check for fragmentation
296     connection->packet_type = AVRCP_SINGLE_PACKET;
297 
298     packet[pos++] = (connection->transaction_label << 4) | (connection->packet_type << 2) | (AVRCP_RESPONSE_FRAME << 1) | 0;
299     // Profile IDentifier (PID)
300     packet[pos++] = BLUETOOTH_SERVICE_CLASS_AV_REMOTE_CONTROL >> 8;
301     packet[pos++] = BLUETOOTH_SERVICE_CLASS_AV_REMOTE_CONTROL & 0x00FF;
302     // command_type
303     packet[pos++] = connection->command_type;
304     // subunit_type | subunit ID
305     packet[pos++] = (connection->subunit_type << 3) | connection->subunit_id;
306     // opcode
307     packet[pos++] = (uint8_t)connection->command_opcode;
308     // operands
309     memcpy(packet+pos, connection->cmd_operands, connection->cmd_operands_length);
310     // printf_hexdump(packet+pos, connection->cmd_operands_length);
311 
312     pos += connection->cmd_operands_length;
313     connection->wait_to_send = 0;
314     return l2cap_send_prepared(cid, pos);
315 }
316 
317 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, avrcp_status_code_t status){
318     // AVRCP_CTYPE_RESPONSE_REJECTED
319     connection->command_type = AVRCP_CTYPE_RESPONSE_ACCEPTED;
320     connection->subunit_type = subunit_type;
321     connection->subunit_id =   subunit_id;
322     connection->command_opcode = opcode;
323     // company id is 3 bytes long
324     int pos = connection->cmd_operands_length;
325     connection->cmd_operands[pos++] = pdu_id;
326     connection->cmd_operands[pos++] = 0;
327     // param length
328     big_endian_store_16(connection->cmd_operands, pos, 1);
329     pos += 2;
330     connection->cmd_operands[pos++] = status;
331     connection->cmd_operands_length = pos;
332     connection->state = AVCTP_W2_SEND_RESPONSE;
333     avrcp_request_can_send_now(connection, connection->l2cap_signaling_cid);
334     return ERROR_CODE_SUCCESS;
335 }
336 
337 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){
338     // AVRCP_CTYPE_RESPONSE_REJECTED
339     connection->command_type = AVRCP_CTYPE_RESPONSE_REJECTED;
340     connection->subunit_type = subunit_type;
341     connection->subunit_id =   subunit_id;
342     connection->command_opcode = opcode;
343     // company id is 3 bytes long
344     int pos = connection->cmd_operands_length;
345     connection->cmd_operands[pos++] = pdu_id;
346     connection->cmd_operands[pos++] = 0;
347     // param length
348     big_endian_store_16(connection->cmd_operands, pos, 1);
349     pos += 2;
350     connection->cmd_operands[pos++] = status;
351     connection->cmd_operands_length = pos;
352     connection->state = AVCTP_W2_SEND_RESPONSE;
353     avrcp_request_can_send_now(connection, connection->l2cap_signaling_cid);
354     return ERROR_CODE_SUCCESS;
355 }
356 
357 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){
358     connection->command_type = AVRCP_CTYPE_RESPONSE_NOT_IMPLEMENTED;
359     connection->subunit_type = subunit_type;
360     connection->subunit_id =   subunit_id;
361     connection->command_opcode = opcode;
362 
363     // company id is 3 bytes long
364     int pos = connection->cmd_operands_length;
365     connection->cmd_operands[pos++] = pdu_id;
366     connection->cmd_operands[pos++] = 0;
367     // param length
368     big_endian_store_16(connection->cmd_operands, pos, 1);
369     pos += 2;
370     connection->cmd_operands[pos++] = event_id;
371     connection->cmd_operands_length = pos;
372 
373     connection->state = AVCTP_W2_SEND_RESPONSE;
374     avrcp_request_can_send_now(connection, connection->l2cap_signaling_cid);
375     return ERROR_CODE_SUCCESS;
376 }
377 
378 static uint8_t avrcp_target_response_vendor_dependent_interim(avrcp_connection_t * connection, avrcp_subunit_type_t subunit_type, avrcp_subunit_id_t subunit_id,
379     avrcp_command_opcode_t opcode, avrcp_pdu_id_t pdu_id, uint8_t event_id, const uint8_t * value, uint16_t value_len){
380     connection->command_type = AVRCP_CTYPE_RESPONSE_INTERIM;
381     connection->subunit_type = subunit_type;
382     connection->subunit_id =   subunit_id;
383     connection->command_opcode = opcode;
384 
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 + value_len);
391     pos += 2;
392     connection->cmd_operands[pos++] = event_id;
393     if (value && value_len > 0){
394         memcpy(connection->cmd_operands + pos, value, value_len);
395         pos += value_len;
396     }
397     connection->cmd_operands_length = pos;
398 
399     connection->state = AVCTP_W2_SEND_RESPONSE;
400     avrcp_request_can_send_now(connection, connection->l2cap_signaling_cid);
401     return ERROR_CODE_SUCCESS;
402 }
403 
404 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){
405     connection->command_type = AVRCP_CTYPE_RESPONSE_INTERIM;
406     connection->subunit_type = subunit_type;
407     connection->subunit_id =   subunit_id;
408     connection->command_opcode = opcode;
409 
410     // company id is 3 bytes long
411     int pos = connection->cmd_operands_length;
412     connection->cmd_operands[pos++] = pdu_id;
413     connection->cmd_operands[pos++] = 0;
414     // param length
415     big_endian_store_16(connection->cmd_operands, pos, 5);
416     pos += 2;
417     connection->cmd_operands[pos++] = AVRCP_NOTIFICATION_EVENT_ADDRESSED_PLAYER_CHANGED;
418     big_endian_read_16( &connection->cmd_operands[pos], connection->addressed_player_id);
419     pos += 2;
420     big_endian_read_16( &connection->cmd_operands[pos], connection->uid_counter);
421     pos += 2;
422 
423     connection->cmd_operands_length = pos;
424     connection->state = AVCTP_W2_SEND_RESPONSE;
425     avrcp_request_can_send_now(connection, connection->l2cap_signaling_cid);
426     return ERROR_CODE_SUCCESS;
427 }
428 
429 
430 // static uint8_t avrcp_target_response_vendor_dependent_changed(avrcp_connection_t * connection, avrcp_pdu_id_t pdu_id, uint8_t event_id){
431 //     connection->command_opcode = AVRCP_CMD_OPCODE_VENDOR_DEPENDENT;
432 //     connection->command_type = AVRCP_CTYPE_RESPONSE_CHANGED_STABLE;
433 //     connection->subunit_type = AVRCP_SUBUNIT_TYPE_PANEL;
434 //     connection->subunit_id = AVRCP_SUBUNIT_ID;
435 
436 //     // company id is 3 bytes long
437 //     int pos = connection->cmd_operands_length;
438 //     connection->cmd_operands[pos++] = pdu_id;
439 //     connection->cmd_operands[pos++] = 0;
440 //     // param length
441 //     big_endian_store_16(connection->cmd_operands, pos, 1);
442 //     pos += 2;
443 //     connection->cmd_operands[pos++] = event_id;
444 //     connection->cmd_operands_length = pos;
445 
446 //     connection->state = AVCTP_W2_SEND_RESPONSE;
447 //     avrcp_request_can_send_now(connection, connection->l2cap_signaling_cid);
448 //     return ERROR_CODE_SUCCESS;
449 // }
450 
451 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){
452     avrcp_connection_t * connection = get_avrcp_connection_for_avrcp_cid(avrcp_cid, &avrcp_target_context);
453     if (!connection){
454         log_error("Could not find a connection.");
455         return ERROR_CODE_UNKNOWN_CONNECTION_IDENTIFIER;
456     }
457     connection->command_type = cmd_type;
458     connection->subunit_type = AVRCP_SUBUNIT_TYPE_PANEL;
459     connection->subunit_id =   AVRCP_SUBUNIT_ID;
460     connection->command_opcode = AVRCP_CMD_OPCODE_PASS_THROUGH;
461 
462     int pos = 0;
463     connection->cmd_operands[pos++] = opid;
464     connection->cmd_operands[pos++] = operands_length;
465     if (operands_length == 1){
466         connection->cmd_operands[pos++] = operand;
467     }
468     connection->cmd_operands_length = pos;
469 
470     connection->state = AVCTP_W2_SEND_RESPONSE;
471     avrcp_request_can_send_now(connection, connection->l2cap_signaling_cid);
472     return ERROR_CODE_SUCCESS;
473 }
474 
475 uint8_t avrcp_target_operation_rejected(uint16_t avrcp_cid, avrcp_operation_id_t opid, uint8_t operands_length, uint8_t operand){
476     return avrcp_target_pass_through_response(avrcp_cid, AVRCP_CTYPE_RESPONSE_REJECTED, opid, operands_length, operand);
477 }
478 
479 uint8_t avrcp_target_operation_accepted(uint16_t avrcp_cid, avrcp_operation_id_t opid, uint8_t operands_length, uint8_t operand){
480     return avrcp_target_pass_through_response(avrcp_cid, AVRCP_CTYPE_RESPONSE_ACCEPTED, opid, operands_length, operand);
481 }
482 
483 uint8_t avrcp_target_operation_not_implemented(uint16_t avrcp_cid, avrcp_operation_id_t opid, uint8_t operands_length, uint8_t operand){
484     return avrcp_target_pass_through_response(avrcp_cid, AVRCP_CTYPE_RESPONSE_ACCEPTED, opid, operands_length, operand);
485 }
486 
487 void avrcp_target_set_unit_info(uint16_t avrcp_cid, avrcp_subunit_type_t unit_type, uint32_t company_id){
488     avrcp_connection_t * connection = get_avrcp_connection_for_avrcp_cid(avrcp_cid, &avrcp_target_context);
489     if (!connection){
490         log_error("avrcp_target_operation_reject: could not find a connection.");
491         return;
492     }
493     connection->unit_type = unit_type;
494     connection->company_id = company_id;
495 }
496 
497 void 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){
498     avrcp_connection_t * connection = get_avrcp_connection_for_avrcp_cid(avrcp_cid, &avrcp_target_context);
499     if (!connection){
500         log_error("avrcp_target_operation_reject: could not find a connection.");
501         return;
502     }
503     connection->subunit_info_type = subunit_type;
504     connection->subunit_info_data = subunit_info_data;
505     connection->subunit_info_data_size = subunit_info_data_size;
506 }
507 
508 static uint8_t avrcp_target_unit_info(avrcp_connection_t * connection){
509     if (connection->state != AVCTP_CONNECTION_OPENED) return ERROR_CODE_COMMAND_DISALLOWED;
510 
511     uint8_t unit = 0;
512     connection->command_type = AVRCP_CTYPE_RESPONSE_IMPLEMENTED_STABLE;
513     connection->subunit_type = AVRCP_SUBUNIT_TYPE_UNIT; //vendor unique
514     connection->subunit_id =   AVRCP_SUBUNIT_ID_IGNORE;
515     connection->command_opcode = AVRCP_CMD_OPCODE_UNIT_INFO;
516 
517     connection->cmd_operands_length = 5;
518     connection->cmd_operands[0] = 0x07;
519     connection->cmd_operands[1] = (connection->unit_type << 4) | unit;
520     // company id is 3 bytes long
521     big_endian_store_32(connection->cmd_operands, 2, connection->company_id);
522 
523     connection->state = AVCTP_W2_SEND_RESPONSE;
524     avrcp_request_can_send_now(connection, connection->l2cap_signaling_cid);
525     return ERROR_CODE_SUCCESS;
526 }
527 
528 
529 static uint8_t avrcp_target_subunit_info(avrcp_connection_t * connection, uint8_t offset){
530     if (connection->state != AVCTP_CONNECTION_OPENED) return ERROR_CODE_COMMAND_DISALLOWED;
531     if (offset - 4 > connection->subunit_info_data_size) return AVRCP_STATUS_INVALID_PARAMETER;
532 
533     connection->command_opcode = AVRCP_CMD_OPCODE_SUBUNIT_INFO;
534     connection->command_type = AVRCP_CTYPE_RESPONSE_IMPLEMENTED_STABLE;
535     connection->subunit_type = AVRCP_SUBUNIT_TYPE_UNIT; //vendor unique
536     connection->subunit_id =   AVRCP_SUBUNIT_ID_IGNORE;
537     // printf("avrcp_target_subunit_info  subunit_type %d\n", connection->subunit_type);
538 
539     uint8_t page = offset / 4;
540     uint8_t extension_code = 7;
541     connection->cmd_operands_length = 5;
542     connection->cmd_operands[0] = (page << 4) | extension_code;
543 
544     memcpy(connection->cmd_operands+1, connection->subunit_info_data + offset, 4);
545 
546     connection->state = AVCTP_W2_SEND_RESPONSE;
547     avrcp_request_can_send_now(connection, connection->l2cap_signaling_cid);
548     return ERROR_CODE_SUCCESS;
549 }
550 
551 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){
552     *out_connection = get_avrcp_connection_for_avrcp_cid(avrcp_cid, &avrcp_target_context);
553     if (!*out_connection){
554         log_error("avrcp tartget: could not find a connection.");
555         return ERROR_CODE_UNKNOWN_CONNECTION_IDENTIFIER;
556     }
557 
558     if ((*out_connection)->state != AVCTP_CONNECTION_OPENED) return ERROR_CODE_COMMAND_DISALLOWED;
559     (*out_connection)->command_opcode  = AVRCP_CMD_OPCODE_VENDOR_DEPENDENT;
560     (*out_connection)->command_type    = AVRCP_CTYPE_RESPONSE_IMPLEMENTED_STABLE;
561     (*out_connection)->subunit_type    = AVRCP_SUBUNIT_TYPE_PANEL;
562     (*out_connection)->subunit_id      = AVRCP_SUBUNIT_ID;
563 
564     (*out_connection)->cmd_operands[(*out_connection)->cmd_operands_length++] = pdu_id;
565     // reserved
566     (*out_connection)->cmd_operands[(*out_connection)->cmd_operands_length++] = 0;
567     // param length
568     big_endian_store_16((*out_connection)->cmd_operands, (*out_connection)->cmd_operands_length, param_length);
569     (*out_connection)->cmd_operands_length += 2;
570     return ERROR_CODE_SUCCESS;
571 }
572 
573 static uint8_t avrcp_target_capability(uint16_t avrcp_cid, avrcp_capability_id_t capability_id, uint8_t capabilities_num, uint8_t * capabilities, uint8_t size){
574     avrcp_connection_t * connection = NULL;
575     uint8_t status = avrcp_prepare_vendor_dependent_response(avrcp_cid, &connection, AVRCP_PDU_ID_GET_CAPABILITIES, 2+size);
576     if (status != ERROR_CODE_SUCCESS) return status;
577 
578     connection->cmd_operands[connection->cmd_operands_length++] = capability_id;
579     connection->cmd_operands[connection->cmd_operands_length++] = capabilities_num;
580     memcpy(connection->cmd_operands+connection->cmd_operands_length, capabilities, size);
581     connection->cmd_operands_length += size;
582 
583     connection->state = AVCTP_W2_SEND_RESPONSE;
584     avrcp_request_can_send_now(connection, connection->l2cap_signaling_cid);
585     return ERROR_CODE_SUCCESS;
586 }
587 
588 uint8_t avrcp_target_supported_events(uint16_t avrcp_cid, uint8_t capabilities_num, uint8_t * capabilities, uint8_t size){
589     return avrcp_target_capability(avrcp_cid, AVRCP_CAPABILITY_ID_EVENT, capabilities_num, capabilities, size);
590 }
591 
592 uint8_t avrcp_target_supported_companies(uint16_t avrcp_cid, uint8_t capabilities_num, uint8_t * capabilities, uint8_t size ){
593     return avrcp_target_capability(avrcp_cid, AVRCP_CAPABILITY_ID_COMPANY, capabilities_num, capabilities, size);
594 }
595 
596 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){
597     avrcp_connection_t * connection = NULL;
598     uint8_t status = avrcp_prepare_vendor_dependent_response(avrcp_cid, &connection, AVRCP_PDU_ID_GET_PLAY_STATUS, 11);
599     if (status != ERROR_CODE_SUCCESS) return status;
600 
601     big_endian_store_32(connection->cmd_operands, connection->cmd_operands_length, song_length_ms);
602     connection->cmd_operands_length += 4;
603     big_endian_store_32(connection->cmd_operands, connection->cmd_operands_length, song_position_ms);
604     connection->cmd_operands_length += 4;
605     connection->cmd_operands[connection->cmd_operands_length++] = play_status;
606 
607     connection->state = AVCTP_W2_SEND_RESPONSE;
608     avrcp_request_can_send_now(connection, connection->l2cap_signaling_cid);
609     return ERROR_CODE_SUCCESS;
610 }
611 
612 static uint8_t avrcp_target_now_playing_info(avrcp_connection_t * connection){
613     if (connection->state != AVCTP_CONNECTION_OPENED) return ERROR_CODE_COMMAND_DISALLOWED;
614     connection->now_playing_info_response = 1;
615     connection->command_opcode  = AVRCP_CMD_OPCODE_VENDOR_DEPENDENT;
616     connection->command_type    = AVRCP_CTYPE_RESPONSE_IMPLEMENTED_STABLE;
617     connection->subunit_type    = AVRCP_SUBUNIT_TYPE_PANEL;
618     connection->subunit_id      = AVRCP_SUBUNIT_ID;
619 
620     connection->state = AVCTP_W2_SEND_RESPONSE;
621     avrcp_request_can_send_now(connection, connection->l2cap_signaling_cid);
622     return ERROR_CODE_SUCCESS;
623 }
624 
625 static uint8_t avrcp_target_store_media_attr(avrcp_connection_t * connection, avrcp_media_attribute_id_t attr_id, const char * value){
626     int index = attr_id - 1;
627     if (!value) return AVRCP_STATUS_INVALID_PARAMETER;
628     connection->now_playing_info[index].value = (uint8_t*)value;
629     connection->now_playing_info[index].len   = strlen(value);
630     // printf("store %lu bytes, %s\n",  strlen(value), value);
631     return ERROR_CODE_SUCCESS;
632 }
633 
634 uint8_t avrcp_target_set_playback_status(uint16_t avrcp_cid, avrcp_playback_status_t playback_status){
635     avrcp_connection_t * connection = get_avrcp_connection_for_avrcp_cid(avrcp_cid, &avrcp_target_context);
636     if (!connection){
637         log_error("avrcp_unit_info: could not find a connection.");
638         return ERROR_CODE_UNKNOWN_CONNECTION_IDENTIFIER;
639     }
640     if (connection->playback_status == playback_status) return ERROR_CODE_SUCCESS;
641 
642     connection->playback_status = playback_status;
643     connection->playback_status_changed = 1;
644     avrcp_request_can_send_now(connection, connection->l2cap_signaling_cid);
645     return ERROR_CODE_SUCCESS;
646 }
647 
648 void avrcp_target_set_now_playing_info(uint16_t avrcp_cid, const avrcp_track_t * current_track, uint16_t total_tracks){
649     avrcp_connection_t * connection = get_avrcp_connection_for_avrcp_cid(avrcp_cid, &avrcp_target_context);
650     if (!connection){
651         log_error("avrcp_unit_info: could not find a connection. cid 0x%02x\n", avrcp_cid);
652         return;
653     }
654     if (!current_track){
655         connection->track_selected = 0;
656         connection->playback_status = AVRCP_PLAYBACK_STATUS_ERROR;
657         return;
658     }
659     memcpy(connection->track_id, current_track->track_id, 8);
660     connection->song_length_ms = current_track->song_length_ms;
661     connection->track_nr = current_track->track_nr;
662     connection->total_tracks = total_tracks;
663     avrcp_target_store_media_attr(connection, AVRCP_MEDIA_ATTR_TITLE, current_track->title);
664     avrcp_target_store_media_attr(connection, AVRCP_MEDIA_ATTR_ARTIST, current_track->artist);
665     avrcp_target_store_media_attr(connection, AVRCP_MEDIA_ATTR_ALBUM, current_track->album);
666     avrcp_target_store_media_attr(connection, AVRCP_MEDIA_ATTR_GENRE, current_track->genre);
667     connection->track_selected = 1;
668 
669     if (connection->notifications_enabled & (1 << AVRCP_NOTIFICATION_EVENT_TRACK_CHANGED)) {
670         connection->track_changed = 1;
671         avrcp_request_can_send_now(connection, connection->l2cap_signaling_cid);
672     }
673     return;
674 }
675 
676 uint8_t avrcp_target_track_changed(uint16_t avrcp_cid, uint8_t * track_id){
677     avrcp_connection_t * connection = get_avrcp_connection_for_avrcp_cid(avrcp_cid, &avrcp_target_context);
678     if (!connection){
679         log_error("avrcp_target_track_changed: could not find connection.");
680         return ERROR_CODE_UNKNOWN_CONNECTION_IDENTIFIER;
681     }
682     if (!track_id) return ERROR_CODE_UNKNOWN_CONNECTION_IDENTIFIER;
683 
684     if (connection->notifications_enabled & (1 << AVRCP_NOTIFICATION_EVENT_TRACK_CHANGED)) {
685         connection->track_changed = 1;
686         memcpy(connection->track_id, track_id, 8);
687         avrcp_request_can_send_now(connection, connection->l2cap_signaling_cid);
688     }
689     return ERROR_CODE_SUCCESS;
690 }
691 
692 uint8_t avrcp_target_playing_content_changed(uint16_t avrcp_cid){
693     avrcp_connection_t * connection = get_avrcp_connection_for_avrcp_cid(avrcp_cid, &avrcp_target_context);
694     if (!connection){
695         log_error("avrcp_target_playing_content_changed: could not find a connection.");
696         return ERROR_CODE_UNKNOWN_CONNECTION_IDENTIFIER;
697     }
698     if (connection->notifications_enabled & (1 << AVRCP_NOTIFICATION_EVENT_NOW_PLAYING_CONTENT_CHANGED)) {
699         connection->playing_content_changed = 1;
700         avrcp_request_can_send_now(connection, connection->l2cap_signaling_cid);
701     }
702     return ERROR_CODE_SUCCESS;
703 }
704 
705 uint8_t avrcp_target_addressed_player_changed(uint16_t avrcp_cid, uint16_t player_id, uint16_t uid_counter){
706     avrcp_connection_t * connection = get_avrcp_connection_for_avrcp_cid(avrcp_cid, &avrcp_target_context);
707     if (!connection){
708         log_error("avrcp_unit_info: could not find a connection.");
709         return ERROR_CODE_UNKNOWN_CONNECTION_IDENTIFIER;
710     }
711     if (connection->notifications_enabled & (1 << AVRCP_NOTIFICATION_EVENT_ADDRESSED_PLAYER_CHANGED)) {
712         // printf("send AVRCP_NOTIFICATION_EVENT_ADDRESSED_PLAYER_CHANGED\n");
713         // connection->addressed_player_changed = 1;
714         connection->uid_counter = uid_counter;
715         connection->addressed_player_id = player_id;
716         // avrcp_request_can_send_now(connection, connection->l2cap_signaling_cid);
717     }
718     return ERROR_CODE_SUCCESS;
719 }
720 
721 uint8_t avrcp_target_battery_status_changed(uint16_t avrcp_cid, avrcp_battery_status_t battery_status){
722     avrcp_connection_t * connection = get_avrcp_connection_for_avrcp_cid(avrcp_cid, &avrcp_target_context);
723     if (!connection){
724         log_error("avrcp_unit_info: could not find a connection.");
725         return ERROR_CODE_UNKNOWN_CONNECTION_IDENTIFIER;
726     }
727     if (connection->battery_status == battery_status) return ERROR_CODE_SUCCESS;
728     if (connection->notifications_enabled & (1 << AVRCP_NOTIFICATION_EVENT_BATT_STATUS_CHANGED)) {
729         connection->battery_status = battery_status;
730         connection->battery_status_changed = 1;
731         avrcp_request_can_send_now(connection, connection->l2cap_signaling_cid);
732     }
733     return ERROR_CODE_SUCCESS;
734 }
735 
736 uint8_t avrcp_target_volume_changed(uint16_t avrcp_cid, uint8_t volume_percentage){
737     avrcp_connection_t * connection = get_avrcp_connection_for_avrcp_cid(avrcp_cid, &avrcp_target_context);
738     if (!connection){
739         log_error("avrcp_unit_info: could not find a connection.");
740         return ERROR_CODE_UNKNOWN_CONNECTION_IDENTIFIER;
741     }
742     if (connection->volume_percentage == volume_percentage) return ERROR_CODE_SUCCESS;
743     if (connection->notifications_enabled & (1 << AVRCP_NOTIFICATION_EVENT_VOLUME_CHANGED )) {
744         connection->volume_percentage = volume_percentage;
745         connection->volume_percentage_changed = 1;
746         avrcp_request_can_send_now(connection, connection->l2cap_signaling_cid);
747     }
748     return ERROR_CODE_SUCCESS;
749 }
750 
751 
752 static uint8_t * avrcp_get_company_id(uint8_t *packet, uint16_t size){
753     UNUSED(size);
754     return packet + 6;
755 }
756 
757 static uint8_t * avrcp_get_pdu(uint8_t *packet, uint16_t size){
758     UNUSED(size);
759     return packet + 9;
760 }
761 
762 static uint8_t avrcp_is_receive_pass_through_cmd(uint8_t operation_id){
763     return operation_id & 0x80;
764 }
765 
766 static void avrcp_handle_l2cap_data_packet_for_signaling_connection(avrcp_connection_t * connection, uint8_t *packet, uint16_t size){
767     UNUSED(connection);
768     UNUSED(packet);
769     UNUSED(size);
770 
771     // uint8_t opcode;
772     uint16_t pid = 0;
773     uint8_t transport_header = packet[0];
774     connection->transaction_label = transport_header >> 4;
775     // uint8_t frame_type = (transport_header & 0x03) >> 1;
776     avrcp_packet_type_t packet_type = (avrcp_packet_type_t) ((transport_header & 0x0F) >> 2);
777     switch (packet_type){
778         case AVRCP_SINGLE_PACKET:
779             pid =  big_endian_read_16(packet, 1);
780             break;
781         case AVRCP_START_PACKET:
782             pid =  big_endian_read_16(packet, 2);
783             break;
784         default:
785             break;
786     }
787 
788     switch (packet_type){
789         case AVRCP_SINGLE_PACKET:
790         case AVRCP_START_PACKET:
791             if (pid != BLUETOOTH_SERVICE_CLASS_AV_REMOTE_CONTROL){
792                 log_info("Invalid pid 0x%02x, expected 0x%02x", connection->invalid_pid, BLUETOOTH_SERVICE_CLASS_AV_REMOTE_CONTROL);
793                 connection->reject_transport_header = 1;
794                 connection->invalid_pid = pid;
795                 connection->transport_header = (connection->transaction_label << 4) | (AVRCP_SINGLE_PACKET << 2 ) | (AVRCP_RESPONSE_FRAME << 1) | 1;
796                 connection->state = AVCTP_W2_SEND_RESPONSE;
797                 avrcp_request_can_send_now(connection, connection->l2cap_signaling_cid);
798                 return;
799             }
800             break;
801         default:
802             break;
803     }
804 
805     // avrcp_command_type_t ctype = (avrcp_command_type_t) packet[3];
806     // uint8_t byte_value = packet[4];
807     avrcp_subunit_type_t subunit_type = (avrcp_subunit_type_t) (packet[4] >> 3);
808     avrcp_subunit_id_t   subunit_id   = (avrcp_subunit_id_t) (packet[4] & 0x07);
809     // opcode = packet[pos++];
810     // printf("    Transport header 0x%02x (transaction_label %d, packet_type %d, frame_type %d, ipid %d), pid 0x%4x\n",
811     //     transport_header, transaction_label, packet_type, frame_type, ipid, pid);
812     // printf_hexdump(packet+pos, size-pos);
813 
814     avrcp_command_opcode_t opcode = (avrcp_command_opcode_t) avrcp_cmd_opcode(packet,size);
815     uint8_t * company_id = avrcp_get_company_id(packet, size);
816     uint8_t * pdu = avrcp_get_pdu(packet, size);
817     // uint16_t param_length = big_endian_read_16(pdu, 2);
818 
819     int pos = 4;
820     uint16_t length;
821     avrcp_pdu_id_t   pdu_id;
822     connection->cmd_operands_length = 0;
823 
824     switch (opcode){
825         case AVRCP_CMD_OPCODE_UNIT_INFO:
826             avrcp_target_unit_info(connection);
827             break;
828         case AVRCP_CMD_OPCODE_SUBUNIT_INFO:{
829             uint8_t offset =  4 * (packet[pos+2]>>4);
830             avrcp_target_subunit_info(connection, offset);
831             break;
832         }
833         case AVRCP_CMD_OPCODE_PASS_THROUGH:{
834             log_info("AVRCP_OPERATION_ID 0x%02x, operands length %d, operand %d", packet[6], packet[7], packet[8]);
835             avrcp_operation_id_t operation_id = (avrcp_operation_id_t) packet[6];
836 
837             if (avrcp_is_receive_pass_through_cmd(operation_id)){
838                 operation_id = (avrcp_operation_id_t) (packet[6] & 0x7F);
839                 avrcp_target_operation_accepted(connection->avrcp_cid, (avrcp_operation_id_t) packet[6], packet[7], packet[8]);
840                 break;
841             }
842 
843             switch (operation_id){
844                 case AVRCP_OPERATION_ID_PLAY:
845                 case AVRCP_OPERATION_ID_PAUSE:
846                 case AVRCP_OPERATION_ID_STOP:
847                 case AVRCP_OPERATION_ID_VOLUME_UP:
848                 case AVRCP_OPERATION_ID_VOLUME_DOWN:
849                 case AVRCP_OPERATION_ID_REWIND:
850                 case AVRCP_OPERATION_ID_FAST_FORWARD:
851                 case AVRCP_OPERATION_ID_FORWARD:
852                 case AVRCP_OPERATION_ID_BACKWARD:
853                 case AVRCP_OPERATION_ID_SKIP:
854                 case AVRCP_OPERATION_ID_MUTE:
855                 case AVRCP_OPERATION_ID_CHANNEL_UP:
856                 case AVRCP_OPERATION_ID_CHANNEL_DOWN:
857                 case AVRCP_OPERATION_ID_SELECT:
858                 case AVRCP_OPERATION_ID_UP:
859                 case AVRCP_OPERATION_ID_DOWN:
860                 case AVRCP_OPERATION_ID_LEFT:
861                 case AVRCP_OPERATION_ID_RIGHT:
862                 case AVRCP_OPERATION_ID_ROOT_MENU:
863                     avrcp_target_operation_accepted(connection->avrcp_cid, (avrcp_operation_id_t) packet[6], packet[7], packet[8]);
864                     avrcp_target_emit_operation(avrcp_target_context.avrcp_callback, connection->avrcp_cid, operation_id, packet[7], packet[8]);
865                     break;
866                 case AVRCP_OPERATION_ID_UNDEFINED:
867                     avrcp_target_operation_not_implemented(connection->avrcp_cid, (avrcp_operation_id_t) packet[6], packet[7], packet[8]);
868                     return;
869                 default:
870                     avrcp_target_operation_not_implemented(connection->avrcp_cid, (avrcp_operation_id_t) packet[6], packet[7], packet[8]);
871                     return;
872             }
873             break;
874         }
875 
876         case AVRCP_CMD_OPCODE_VENDOR_DEPENDENT:
877             pdu_id = (avrcp_pdu_id_t) pdu[0];
878             // 1 - reserved
879             // 2-3 param length,
880             length = big_endian_read_16(pdu, 2);
881             memcpy(connection->cmd_operands, company_id, 3);
882             connection->cmd_operands_length = 3;
883             switch (pdu_id){
884                 case AVRCP_PDU_ID_SET_ADDRESSED_PLAYER:{
885                     if (length == 0){
886                         avrcp_target_response_reject(connection, subunit_type, subunit_id, opcode, pdu_id, AVRCP_STATUS_INVALID_PLAYER_ID);
887                         break;
888                     }
889                     avrcp_target_response_accept(connection, subunit_type, subunit_id, opcode, pdu_id, AVRCP_STATUS_SUCCESS);
890                     break;
891                 }
892                 case AVRCP_PDU_ID_GET_CAPABILITIES:{
893                     avrcp_capability_id_t capability_id = (avrcp_capability_id_t) pdu[pos];
894                     switch (capability_id){
895                         case AVRCP_CAPABILITY_ID_EVENT:
896                             avrcp_target_emit_respond_vendor_dependent_query(avrcp_target_context.avrcp_callback, connection->avrcp_cid, AVRCP_SUBEVENT_EVENT_IDS_QUERY);
897                             break;
898                         case AVRCP_CAPABILITY_ID_COMPANY:
899                             avrcp_target_emit_respond_vendor_dependent_query(avrcp_target_context.avrcp_callback, connection->avrcp_cid, AVRCP_SUBEVENT_COMPANY_IDS_QUERY);
900                             break;
901                         default:
902                             avrcp_target_response_reject(connection, subunit_type, subunit_id, opcode, pdu_id, AVRCP_STATUS_INVALID_PARAMETER);
903                             break;
904                     }
905                     break;
906                 }
907                 case AVRCP_PDU_ID_GET_PLAY_STATUS:
908                     avrcp_target_emit_respond_vendor_dependent_query(avrcp_target_context.avrcp_callback, connection->avrcp_cid, AVRCP_SUBEVENT_PLAY_STATUS_QUERY);
909                     break;
910                 case AVRCP_PDU_ID_REQUEST_ABORT_CONTINUING_RESPONSE:
911                     connection->cmd_operands[0] = pdu[4];
912                     connection->abort_continue_response = 1;
913                     avrcp_request_can_send_now(connection, connection->l2cap_signaling_cid);
914                     break;
915                 case AVRCP_PDU_ID_REQUEST_CONTINUING_RESPONSE:
916                     if (pdu[4] != AVRCP_PDU_ID_GET_ELEMENT_ATTRIBUTES){
917                         avrcp_target_response_reject(connection, subunit_type, subunit_id, opcode, pdu_id, AVRCP_STATUS_INVALID_COMMAND);
918                         return;
919                     }
920                     connection->now_playing_info_response = 1;
921                     avrcp_request_can_send_now(connection, connection->l2cap_signaling_cid);
922                     break;
923                 case AVRCP_PDU_ID_GET_ELEMENT_ATTRIBUTES:{
924                     uint8_t play_identifier[8];
925                     memset(play_identifier, 0, 8);
926                     if (memcmp(pdu+pos, play_identifier, 8) != 0) {
927                         avrcp_target_response_reject(connection, subunit_type, subunit_id, opcode, pdu_id, AVRCP_STATUS_INVALID_PARAMETER);
928                         return;
929                     }
930                     pos += 8;
931                     uint8_t attribute_count = pdu[pos++];
932                     // printf("AVRCP_PDU_ID_GET_ELEMENT_ATTRIBUTES attribute count %d\n", attribute_count);
933                     connection->next_attr_id = AVRCP_MEDIA_ATTR_NONE;
934                     if (!attribute_count){
935                         connection->now_playing_info_attr_bitmap = 0xFE;
936                     } else {
937                         int i;
938                         connection->now_playing_info_attr_bitmap = 0;
939                         for (i=0; i < attribute_count; i++){
940                             uint16_t attr_id = big_endian_read_16(pdu, pos);
941                             pos += 2;
942                             connection->now_playing_info_attr_bitmap |= (1 << attr_id);
943                         }
944                     }
945                     log_info("now_playing_info_attr_bitmap 0x%02x", connection->now_playing_info_attr_bitmap);
946                     avrcp_target_now_playing_info(connection);
947                     break;
948                 }
949                 case AVRCP_PDU_ID_REGISTER_NOTIFICATION:{
950                     // 0 - pdu id
951                     // 1 - reserved
952                     // 2-3 param length
953                     avrcp_notification_event_id_t event_id = (avrcp_notification_event_id_t) pdu[4];
954                     uint16_t event_mask = (1 << event_id);
955 
956                     switch (event_id){
957                         case AVRCP_NOTIFICATION_EVENT_TRACK_CHANGED:
958                             connection->notifications_enabled |= event_mask;
959                             if (connection->track_selected){
960                                 avrcp_target_response_vendor_dependent_interim(connection, subunit_type, subunit_id, opcode, pdu_id, event_id, AVRCP_NOTIFICATION_TRACK_SELECTED, 8);
961                             } else {
962                                 avrcp_target_response_vendor_dependent_interim(connection, subunit_type, subunit_id, opcode, pdu_id, event_id, AVRCP_NOTIFICATION_TRACK_NOT_SELECTED, 8);
963                             }
964                             break;
965                         case AVRCP_NOTIFICATION_EVENT_PLAYBACK_STATUS_CHANGED:
966                             connection->notifications_enabled |= event_mask;
967                             avrcp_target_response_vendor_dependent_interim(connection, subunit_type, subunit_id, opcode, pdu_id, event_id, (const uint8_t *)&connection->playback_status, 1);
968                             break;
969                         case AVRCP_NOTIFICATION_EVENT_NOW_PLAYING_CONTENT_CHANGED:
970                             connection->notifications_enabled |= event_mask;
971                             avrcp_target_response_vendor_dependent_interim(connection, subunit_type, subunit_id, opcode, pdu_id, event_id, NULL, 0);
972                             break;
973                         case AVRCP_NOTIFICATION_EVENT_VOLUME_CHANGED:
974                             connection->notifications_enabled |= event_mask;
975                             avrcp_target_response_vendor_dependent_interim(connection, subunit_type, subunit_id, opcode, pdu_id, event_id, (const uint8_t *)&connection->volume_percentage, 1);
976                             break;
977                         case AVRCP_NOTIFICATION_EVENT_BATT_STATUS_CHANGED:
978                             connection->notifications_enabled |= event_mask;
979                             avrcp_target_response_vendor_dependent_interim(connection, subunit_type, subunit_id, opcode, pdu_id, event_id, (const uint8_t *)&connection->battery_status, 1);
980                             break;
981                         case AVRCP_NOTIFICATION_EVENT_AVAILABLE_PLAYERS_CHANGED:
982                         case AVRCP_NOTIFICATION_EVENT_PLAYER_APPLICATION_SETTING_CHANGED:
983                         case AVRCP_NOTIFICATION_EVENT_UIDS_CHANGED:
984                             avrcp_target_response_not_implemented(connection, subunit_type, subunit_id, opcode, pdu_id, event_id);
985                             return;
986                         case AVRCP_NOTIFICATION_EVENT_ADDRESSED_PLAYER_CHANGED:
987                             connection->notifications_enabled |= event_mask;
988                             avrcp_target_response_addressed_player_changed_interim(connection, subunit_type, subunit_id, opcode, pdu_id);
989                             return;
990                         default:
991                             avrcp_target_response_reject(connection, subunit_type, subunit_id, opcode, pdu_id, AVRCP_STATUS_INVALID_PARAMETER);
992                             return;
993                     }
994                     break;
995                 }
996                 case AVRCP_PDU_ID_SET_ABSOLUTE_VOLUME: {
997                     if (length != 1){
998                         avrcp_target_response_reject(connection, subunit_type, subunit_id, opcode, pdu_id, AVRCP_STATUS_INVALID_COMMAND);
999                         break;
1000                     }
1001 
1002                     uint8_t absolute_volume = pdu[4];
1003                     if (absolute_volume < 0x80){
1004                         connection->volume_percentage = absolute_volume;
1005                     }
1006                     avrcp_target_response_accept(connection, subunit_type, subunit_id, opcode, pdu_id, (avrcp_status_code_t) connection->volume_percentage);
1007                     break;
1008                 }
1009                 default:
1010                     log_info("AVRCP target: unhandled pdu id 0x%02x", pdu_id);
1011                     avrcp_target_response_reject(connection, subunit_type, subunit_id, opcode, pdu_id, AVRCP_STATUS_INVALID_COMMAND);
1012                     break;
1013             }
1014             break;
1015         default:
1016             log_info("AVRCP target: opcode 0x%02x not implemented", avrcp_cmd_opcode(packet,size));
1017             break;
1018     }
1019 }
1020 
1021 #if 0
1022 static int avrcp_target_send_addressed_player_changed_notification(uint16_t cid, avrcp_connection_t * connection, uint16_t uid, uint16_t uid_counter){
1023     if (!connection){
1024         log_error("avrcp tartget: could not find a connection.");
1025         return ERROR_CODE_UNKNOWN_CONNECTION_IDENTIFIER;
1026     }
1027     connection->command_opcode  = AVRCP_CMD_OPCODE_VENDOR_DEPENDENT;
1028     connection->command_type    = AVRCP_CTYPE_RESPONSE_CHANGED_STABLE;
1029     connection->subunit_type    = AVRCP_SUBUNIT_TYPE_PANEL;
1030     connection->subunit_id      = AVRCP_SUBUNIT_ID;
1031 
1032     uint16_t pos = 0;
1033     l2cap_reserve_packet_buffer();
1034     uint8_t * packet = l2cap_get_outgoing_buffer();
1035 
1036     connection->packet_type = AVRCP_SINGLE_PACKET;
1037     packet[pos++] = (connection->transaction_label << 4) | (connection->packet_type << 2) | (AVRCP_RESPONSE_FRAME << 1) | 0;
1038     // Profile IDentifier (PID)
1039     packet[pos++] = BLUETOOTH_SERVICE_CLASS_AV_REMOTE_CONTROL >> 8;
1040     packet[pos++] = BLUETOOTH_SERVICE_CLASS_AV_REMOTE_CONTROL & 0x00FF;
1041 
1042     // command_type
1043     packet[pos++] = connection->command_type;
1044     // subunit_type | subunit ID
1045     packet[pos++] = (connection->subunit_type << 3) | connection->subunit_id;
1046     // opcode
1047     packet[pos++] = (uint8_t)connection->command_opcode;
1048 
1049     // company id is 3 bytes long
1050     big_endian_store_24(packet, pos, BT_SIG_COMPANY_ID);
1051     pos += 3;
1052 
1053     packet[pos++] = AVRCP_PDU_ID_REGISTER_NOTIFICATION;
1054     packet[pos++] = 0;
1055     big_endian_store_16(packet, pos, 5);
1056     pos += 2;
1057     packet[pos++] = AVRCP_NOTIFICATION_EVENT_ADDRESSED_PLAYER_CHANGED;
1058     big_endian_store_16(packet, pos, uid);
1059     pos += 2;
1060     big_endian_store_16(packet, pos, uid_counter);
1061     pos += 2;
1062 
1063     connection->wait_to_send = 0;
1064     return l2cap_send_prepared(cid, pos);
1065 }
1066 #endif
1067 
1068 static int avrcp_target_send_notification(uint16_t cid, avrcp_connection_t * connection, uint8_t notification_id, uint8_t * value, uint16_t value_len){
1069     if (!connection){
1070         log_error("avrcp tartget: could not find a connection.");
1071         return ERROR_CODE_UNKNOWN_CONNECTION_IDENTIFIER;
1072     }
1073 
1074     connection->command_opcode  = AVRCP_CMD_OPCODE_VENDOR_DEPENDENT;
1075     connection->command_type    = AVRCP_CTYPE_RESPONSE_CHANGED_STABLE;
1076     connection->subunit_type    = AVRCP_SUBUNIT_TYPE_PANEL;
1077     connection->subunit_id      = AVRCP_SUBUNIT_ID;
1078 
1079     uint16_t pos = 0;
1080     l2cap_reserve_packet_buffer();
1081     uint8_t * packet = l2cap_get_outgoing_buffer();
1082     uint16_t  size   = l2cap_get_remote_mtu_for_local_cid(connection->l2cap_signaling_cid);
1083 
1084     connection->packet_type = AVRCP_SINGLE_PACKET;
1085     packet[pos++] = (connection->transaction_label << 4) | (connection->packet_type << 2) | (AVRCP_RESPONSE_FRAME << 1) | 0;
1086     // Profile IDentifier (PID)
1087     packet[pos++] = BLUETOOTH_SERVICE_CLASS_AV_REMOTE_CONTROL >> 8;
1088     packet[pos++] = BLUETOOTH_SERVICE_CLASS_AV_REMOTE_CONTROL & 0x00FF;
1089 
1090     // command_type
1091     packet[pos++] = connection->command_type;
1092     // subunit_type | subunit ID
1093     packet[pos++] = (connection->subunit_type << 3) | connection->subunit_id;
1094     // opcode
1095     packet[pos++] = (uint8_t)connection->command_opcode;
1096 
1097     // company id is 3 bytes long
1098     big_endian_store_24(packet, pos, BT_SIG_COMPANY_ID);
1099     pos += 3;
1100 
1101     packet[pos++] = AVRCP_PDU_ID_REGISTER_NOTIFICATION;
1102     packet[pos++] = 0;
1103     uint16_t remainig_outgoing_buffer_size = size > (value_len + 2 + 1) ? size - (value_len + 2 + 1): 0;
1104     uint16_t caped_value_len = value_len > remainig_outgoing_buffer_size ? remainig_outgoing_buffer_size : value_len;
1105     big_endian_store_16(packet, pos, caped_value_len);
1106     pos += 2;
1107     packet[pos++] = notification_id;
1108 
1109     memcpy(packet+pos, value, caped_value_len);
1110     pos += caped_value_len;
1111     connection->wait_to_send = 0;
1112     return l2cap_send_prepared(cid, pos);
1113 }
1114 
1115 static void avrcp_target_reset_notification(avrcp_connection_t * connection, uint8_t notification_id){
1116     if (!connection){
1117         log_error("avrcp tartget: could not find a connection.");
1118         return;
1119     }
1120     connection->notifications_enabled &= ~(1 << notification_id);
1121     connection->command_opcode  = AVRCP_CMD_OPCODE_VENDOR_DEPENDENT;
1122 
1123 }
1124 
1125 static void avrcp_target_packet_handler(uint8_t packet_type, uint16_t channel, uint8_t *packet, uint16_t size){
1126     avrcp_connection_t * connection;
1127     switch (packet_type) {
1128         case L2CAP_DATA_PACKET:
1129             connection = get_avrcp_connection_for_l2cap_signaling_cid(channel, &avrcp_target_context);
1130             if (!connection) break;
1131             avrcp_handle_l2cap_data_packet_for_signaling_connection(connection, packet, size);
1132             break;
1133         case HCI_EVENT_PACKET:
1134             switch (hci_event_packet_get_type(packet)){
1135                 case L2CAP_EVENT_CAN_SEND_NOW:{
1136                     connection = get_avrcp_connection_for_l2cap_signaling_cid(channel, &avrcp_target_context);
1137                     if (!connection) {
1138                         log_error("Connection not found\n");
1139                         break;
1140                     }
1141 
1142                     if (connection->abort_continue_response){
1143                         connection->abort_continue_response = 0;
1144                         connection->now_playing_info_response = 0;
1145                         avrcp_target_abort_continue_response(connection->l2cap_signaling_cid, connection);
1146                         break;
1147                     }
1148 
1149                     if (connection->now_playing_info_response){
1150                         connection->now_playing_info_response = 0;
1151                         avrcp_target_send_now_playing_info(connection->l2cap_signaling_cid, connection);
1152                         break;
1153                     }
1154 
1155                     if (connection->track_changed){
1156                         connection->track_changed = 0;
1157                         avrcp_target_send_notification(connection->l2cap_signaling_cid, connection, AVRCP_NOTIFICATION_EVENT_TRACK_CHANGED, connection->track_id, 8);
1158                         avrcp_target_reset_notification(connection, AVRCP_NOTIFICATION_EVENT_TRACK_CHANGED);
1159                         avrcp_request_can_send_now(connection, connection->l2cap_signaling_cid);
1160                         break;
1161                     }
1162 
1163                     if (connection->playback_status_changed){
1164                         connection->playback_status_changed = 0;
1165                         avrcp_target_send_notification(connection->l2cap_signaling_cid, connection, AVRCP_NOTIFICATION_EVENT_PLAYBACK_STATUS_CHANGED, &connection->playback_status_changed, 1);
1166                         avrcp_target_reset_notification(connection, AVRCP_NOTIFICATION_EVENT_PLAYBACK_STATUS_CHANGED);
1167                         avrcp_request_can_send_now(connection, connection->l2cap_signaling_cid);
1168                         break;
1169                     }
1170 
1171                     // if (connection->addressed_player_changed){
1172                     //     connection->playback_status_changed = 0;
1173                     //     avrcp_target_send_addressed_player_changed_notification(connection->l2cap_signaling_cid, connection, connection->addressed_player_id, connection->uid_counter);
1174                     //     avrcp_target_reset_notification(connection, AVRCP_NOTIFICATION_EVENT_ADDRESSED_PLAYER_CHANGED);
1175                     //     avrcp_request_can_send_now(connection, connection->l2cap_signaling_cid);
1176                     //     break;
1177                     // }
1178 
1179                     if (connection->playing_content_changed){
1180                         connection->playing_content_changed = 0;
1181                         avrcp_target_send_notification(connection->l2cap_signaling_cid, connection, AVRCP_NOTIFICATION_EVENT_NOW_PLAYING_CONTENT_CHANGED, NULL, 0);
1182                         avrcp_target_reset_notification(connection, AVRCP_NOTIFICATION_EVENT_NOW_PLAYING_CONTENT_CHANGED);
1183                         avrcp_request_can_send_now(connection, connection->l2cap_signaling_cid);
1184                         break;
1185                     }
1186 
1187                     if (connection->battery_status_changed){
1188                         connection->battery_status_changed = 0;
1189                         avrcp_target_send_notification(connection->l2cap_signaling_cid, connection, AVRCP_NOTIFICATION_EVENT_BATT_STATUS_CHANGED, (uint8_t *)&connection->battery_status, 1);
1190                         avrcp_target_reset_notification(connection, AVRCP_NOTIFICATION_EVENT_BATT_STATUS_CHANGED);
1191                         avrcp_request_can_send_now(connection, connection->l2cap_signaling_cid);
1192                         break;
1193                     }
1194 
1195                     if (connection->volume_percentage_changed){
1196                         connection->volume_percentage_changed = 0;
1197                         avrcp_target_send_notification(connection->l2cap_signaling_cid, connection, AVRCP_NOTIFICATION_EVENT_VOLUME_CHANGED, &connection->volume_percentage, 1);
1198                         avrcp_target_reset_notification(connection, AVRCP_NOTIFICATION_EVENT_VOLUME_CHANGED);
1199                         avrcp_request_can_send_now(connection, connection->l2cap_signaling_cid);
1200                         break;
1201                     }
1202 
1203                     if (connection->reject_transport_header){
1204                         printf(" reject_transport_header\n");
1205                         connection->state = AVCTP_CONNECTION_OPENED;
1206                         connection->reject_transport_header = 0;
1207                         l2cap_reserve_packet_buffer();
1208                         uint8_t * out_buffer = l2cap_get_outgoing_buffer();
1209                         out_buffer[0] = connection->transport_header;
1210                         big_endian_store_16(out_buffer, 1, connection->invalid_pid);
1211                         l2cap_send_prepared(connection->l2cap_signaling_cid, 3);
1212                         avrcp_request_can_send_now(connection, connection->l2cap_signaling_cid);
1213                         break;
1214                     }
1215 
1216 
1217                     switch (connection->state){
1218                         case AVCTP_W2_SEND_RESPONSE:
1219                             connection->state = AVCTP_CONNECTION_OPENED;
1220                             // if (connection->now_playing_info_response){
1221                             //     connection->now_playing_info_response = 0;
1222                             //     avrcp_target_send_now_playing_info(connection->l2cap_signaling_cid, connection);
1223                             //     break;
1224                             // }
1225                             avrcp_target_send_response(connection->l2cap_signaling_cid, connection);
1226                             break;
1227                         default:
1228                             return;
1229                     }
1230                     break;
1231             }
1232             default:
1233                 avrcp_packet_handler(packet_type, channel, packet, size, &avrcp_target_context);
1234                 break;
1235         }
1236         default:
1237             break;
1238     }
1239 }
1240 
1241 void avrcp_target_init(void){
1242     avrcp_target_context.role = AVRCP_TARGET;
1243     avrcp_target_context.connections = NULL;
1244     avrcp_target_context.packet_handler = avrcp_target_packet_handler;
1245     l2cap_register_service(&avrcp_target_packet_handler, BLUETOOTH_PROTOCOL_AVCTP, 0xffff, LEVEL_2);
1246 }
1247 
1248 void avrcp_target_register_packet_handler(btstack_packet_handler_t callback){
1249     if (callback == NULL){
1250         log_error("avrcp_register_packet_handler called with NULL callback");
1251         return;
1252     }
1253     avrcp_target_context.avrcp_callback = callback;
1254 }
1255 
1256 uint8_t avrcp_target_connect(bd_addr_t bd_addr, uint16_t * avrcp_cid){
1257     return avrcp_connect(bd_addr, &avrcp_target_context, avrcp_cid);
1258 }
1259 
1260 uint8_t avrcp_target_disconnect(uint16_t avrcp_cid){
1261     avrcp_connection_t * connection = get_avrcp_connection_for_avrcp_cid(avrcp_cid, &avrcp_target_context);
1262     if (!connection){
1263         log_error("avrcp_get_capabilities: could not find a connection.");
1264         return ERROR_CODE_UNKNOWN_CONNECTION_IDENTIFIER;
1265     }
1266     if (connection->state != AVCTP_CONNECTION_OPENED) return ERROR_CODE_COMMAND_DISALLOWED;
1267     l2cap_disconnect(connection->l2cap_signaling_cid, 0);
1268     return ERROR_CODE_SUCCESS;
1269 }
1270 
1271