xref: /btstack/src/classic/avdtp.c (revision 235946f152c66eb4ba735043adb492f7a538d15c)

/*
 * Copyright (C) 2016 BlueKitchen GmbH
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. Neither the name of the copyright holders nor the names of
 *    contributors may be used to endorse or promote products derived
 *    from this software without specific prior written permission.
 * 4. Any redistribution, use, or modification is done solely for
 *    personal benefit and not for any commercial purpose or for
 *    monetary gain.
 *
 * THIS SOFTWARE IS PROVIDED BY BLUEKITCHEN GMBH AND CONTRIBUTORS
 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL MATTHIAS
 * RINGWALD OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
 * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
 * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
 * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF
 * THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 *
 * Please inquire about commercial licensing options at
 * [email protected]
 *
 */

#define __BTSTACK_FILE__ "avdtp.c"


#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>

#include "btstack.h"
#include "avdtp.h"
#include "avdtp_util.h"
#include "avdtp_acceptor.h"
#include "avdtp_initiator.h"

static uint8_t audio_samples_storage[44100*4]; // 1s buffer
// static btstack_ring_buffer_t audio_ring_buffer;

static uint8_t sbc_samples_storage[44100*4];
// static btstack_ring_buffer_t sbc_ring_buffer;

static void (*handle_media_data)(avdtp_stream_endpoint_t * stream_endpoint, uint8_t *packet, uint16_t size);

void avdtp_register_media_transport_category(avdtp_stream_endpoint_t * stream_endpoint){
    if (!stream_endpoint){
        log_error("avdtp_register_media_transport_category: stream endpoint with given seid is not registered");
        return;
    }
    uint16_t bitmap = store_bit16(stream_endpoint->sep.registered_service_categories, AVDTP_MEDIA_TRANSPORT, 1);
    stream_endpoint->sep.registered_service_categories = bitmap;
    printf("registered services AVDTP_MEDIA_TRANSPORT(%d) %02x\n", AVDTP_MEDIA_TRANSPORT, stream_endpoint->sep.registered_service_categories);
}

void avdtp_register_reporting_category(avdtp_stream_endpoint_t * stream_endpoint){
    if (!stream_endpoint){
        log_error("avdtp_register_media_transport_category: stream endpoint with given seid is not registered");
        return;
    }
    uint16_t bitmap = store_bit16(stream_endpoint->sep.registered_service_categories, AVDTP_REPORTING, 1);
    stream_endpoint->sep.registered_service_categories = bitmap;
}

void avdtp_register_delay_reporting_category(avdtp_stream_endpoint_t * stream_endpoint){
    if (!stream_endpoint){
        log_error("avdtp_register_media_transport_category: stream endpoint with given seid is not registered");
        return;
    }
    uint16_t bitmap = store_bit16(stream_endpoint->sep.registered_service_categories, AVDTP_DELAY_REPORTING, 1);
    stream_endpoint->sep.registered_service_categories = bitmap;
}

void avdtp_register_recovery_category(avdtp_stream_endpoint_t * stream_endpoint, uint8_t maximum_recovery_window_size, uint8_t maximum_number_media_packets){
    if (!stream_endpoint){
        log_error("avdtp_register_media_transport_category: stream endpoint with given seid is not registered");
        return;
    }
    uint16_t bitmap = store_bit16(stream_endpoint->sep.registered_service_categories, AVDTP_RECOVERY, 1);
    stream_endpoint->sep.registered_service_categories = bitmap;
    stream_endpoint->sep.capabilities.recovery.recovery_type = 0x01; // 0x01 = RFC2733
    stream_endpoint->sep.capabilities.recovery.maximum_recovery_window_size = maximum_recovery_window_size;
    stream_endpoint->sep.capabilities.recovery.maximum_number_media_packets = maximum_number_media_packets;
}

void avdtp_register_content_protection_category(avdtp_stream_endpoint_t * stream_endpoint, uint16_t cp_type, const uint8_t * cp_type_value, uint8_t cp_type_value_len){
    if (!stream_endpoint){
        log_error("avdtp_register_media_transport_category: stream endpoint with given seid is not registered");
        return;
    }
    uint16_t bitmap = store_bit16(stream_endpoint->sep.registered_service_categories, AVDTP_CONTENT_PROTECTION, 1);
    stream_endpoint->sep.registered_service_categories = bitmap;
    stream_endpoint->sep.capabilities.content_protection.cp_type = cp_type;
    stream_endpoint->sep.capabilities.content_protection.cp_type_value = cp_type_value;
    stream_endpoint->sep.capabilities.content_protection.cp_type_value_len = cp_type_value_len;
}

void avdtp_register_header_compression_category(avdtp_stream_endpoint_t * stream_endpoint, uint8_t back_ch, uint8_t media, uint8_t recovery){
    if (!stream_endpoint){
        log_error("avdtp_register_media_transport_category: stream endpoint with given seid is not registered");
        return;
    }
    uint16_t bitmap = store_bit16(stream_endpoint->sep.registered_service_categories, AVDTP_HEADER_COMPRESSION, 1);
    stream_endpoint->sep.registered_service_categories = bitmap;
    stream_endpoint->sep.capabilities.header_compression.back_ch = back_ch;
    stream_endpoint->sep.capabilities.header_compression.media = media;
    stream_endpoint->sep.capabilities.header_compression.recovery = recovery;
}

void avdtp_register_media_codec_category(avdtp_stream_endpoint_t * stream_endpoint, avdtp_media_type_t media_type, avdtp_media_codec_type_t media_codec_type, const uint8_t * media_codec_info, uint16_t media_codec_info_len){
    if (!stream_endpoint){
        log_error("avdtp_register_media_transport_category: stream endpoint with given seid is not registered");
        return;
    }
    uint16_t bitmap = store_bit16(stream_endpoint->sep.registered_service_categories, AVDTP_MEDIA_CODEC, 1);
    stream_endpoint->sep.registered_service_categories = bitmap;
    printf("registered services AVDTP_MEDIA_CODEC(%d) %02x\n", AVDTP_MEDIA_CODEC, stream_endpoint->sep.registered_service_categories);
    stream_endpoint->sep.capabilities.media_codec.media_type = media_type;
    stream_endpoint->sep.capabilities.media_codec.media_codec_type = media_codec_type;
    stream_endpoint->sep.capabilities.media_codec.media_codec_information = media_codec_info;
    stream_endpoint->sep.capabilities.media_codec.media_codec_information_len = media_codec_info_len;
}

void avdtp_register_multiplexing_category(avdtp_stream_endpoint_t * stream_endpoint, uint8_t fragmentation){
    if (!stream_endpoint){
        log_error("avdtp_register_media_transport_category: stream endpoint with given seid is not registered");
        return;
    }
    uint16_t bitmap = store_bit16(stream_endpoint->sep.registered_service_categories, AVDTP_MULTIPLEXING, 1);
    stream_endpoint->sep.registered_service_categories = bitmap;
    stream_endpoint->sep.capabilities.multiplexing_mode.fragmentation = fragmentation;
}


/* START: tracking can send now requests pro l2cap cid */
void avdtp_handle_can_send_now(avdtp_connection_t * connection, uint16_t l2cap_cid, avdtp_context_t * context){
    if (connection->wait_to_send_acceptor){
        connection->wait_to_send_acceptor = 0;
        avdtp_acceptor_stream_config_subsm_run(connection, context);
    } else if (connection->wait_to_send_initiator){
        connection->wait_to_send_initiator = 0;
        avdtp_initiator_stream_config_subsm_run(connection, context);
    } else if (connection->wait_to_send_self){
        connection->wait_to_send_self = 0;
        if (connection->disconnect){
            btstack_linked_list_iterator_t it;
            btstack_linked_list_iterator_init(&it, &context->stream_endpoints);
            while (btstack_linked_list_iterator_has_next(&it)){
                avdtp_stream_endpoint_t * stream_endpoint = (avdtp_stream_endpoint_t *)btstack_linked_list_iterator_next(&it);
                if (stream_endpoint->connection == connection){
                    if (stream_endpoint->state >= AVDTP_STREAM_ENDPOINT_OPENED && stream_endpoint->state != AVDTP_STREAM_ENDPOINT_W4_L2CAP_FOR_MEDIA_DISCONNECTED){
                        stream_endpoint->state = AVDTP_STREAM_ENDPOINT_W4_L2CAP_FOR_MEDIA_DISCONNECTED;
                        avdtp_request_can_send_now_self(connection, connection->l2cap_signaling_cid);
                        l2cap_disconnect(stream_endpoint->l2cap_media_cid, 0);
                        return;
                    }
                }
            }
            connection->disconnect = 0;
            connection->state = AVDTP_SIGNALING_CONNECTION_W4_L2CAP_DISCONNECTED;
            l2cap_disconnect(connection->l2cap_signaling_cid, 0);
            return;
        }
    }

    // re-register
    int more_to_send = connection->wait_to_send_acceptor || connection->wait_to_send_initiator || connection->wait_to_send_self;
    if (more_to_send){
        l2cap_request_can_send_now_event(l2cap_cid);
    }
}
/* END: tracking can send now requests pro l2cap cid */

avdtp_connection_t * avdtp_create_connection(bd_addr_t remote_addr, avdtp_context_t * context){
    avdtp_connection_t * connection = btstack_memory_avdtp_connection_get();
    memset(connection, 0, sizeof(avdtp_connection_t));
    connection->state = AVDTP_SIGNALING_CONNECTION_IDLE;
    connection->initiator_transaction_label++;
    memcpy(connection->remote_addr, remote_addr, 6);
    btstack_linked_list_add(&context->connections, (btstack_linked_item_t *) connection);
    return connection;
}

avdtp_stream_endpoint_t * avdtp_create_stream_endpoint(avdtp_sep_type_t sep_type, avdtp_media_type_t media_type, avdtp_context_t * context){
    avdtp_stream_endpoint_t * stream_endpoint = btstack_memory_avdtp_stream_endpoint_get();
    memset(stream_endpoint, 0, sizeof(avdtp_stream_endpoint_t));
    context->stream_endpoints_id_counter++;
    stream_endpoint->sep.seid = context->stream_endpoints_id_counter;
    stream_endpoint->sep.media_type = media_type;
    stream_endpoint->sep.type = sep_type;

    memset(audio_samples_storage, 0, sizeof(audio_samples_storage));
    btstack_ring_buffer_init(&stream_endpoint->audio_ring_buffer, audio_samples_storage, sizeof(audio_samples_storage));

    memset(sbc_samples_storage, 0, sizeof(sbc_samples_storage));
    btstack_ring_buffer_init(&stream_endpoint->sbc_ring_buffer, sbc_samples_storage, sizeof(sbc_samples_storage));


    btstack_linked_list_add(&context->stream_endpoints, (btstack_linked_item_t *) stream_endpoint);
    return stream_endpoint;
}


static void handle_l2cap_data_packet_for_signaling_connection(avdtp_connection_t * connection, uint8_t *packet, uint16_t size, avdtp_context_t * context){
    int offset = avdtp_read_signaling_header(&connection->signaling_packet, packet, size);
    switch (connection->signaling_packet.message_type){
        case AVDTP_CMD_MSG:
            avdtp_acceptor_stream_config_subsm(connection, packet, size, offset, context);
            break;
        default:
            avdtp_initiator_stream_config_subsm(connection, packet, size, offset, context);
            break;
    }
}

static void stream_endpoint_state_machine(avdtp_connection_t * connection, avdtp_stream_endpoint_t * stream_endpoint, uint8_t packet_type, uint8_t event, uint8_t *packet, uint16_t size, avdtp_context_t * context){
    uint16_t local_cid;
    switch (packet_type){
        case L2CAP_DATA_PACKET:{
            int offset = avdtp_read_signaling_header(&connection->signaling_packet, packet, size);
            if (connection->signaling_packet.message_type == AVDTP_CMD_MSG){
                avdtp_acceptor_stream_config_subsm(connection, packet, size, offset, context);
            } else {
                avdtp_initiator_stream_config_subsm(connection, packet, size, offset, context);
            }
            break;
        }
        case HCI_EVENT_PACKET:
            switch (event){
                case L2CAP_EVENT_CHANNEL_OPENED:
                    if (stream_endpoint->l2cap_media_cid == 0){
                        if (stream_endpoint->state != AVDTP_STREAM_ENDPOINT_W4_L2CAP_FOR_MEDIA_CONNECTED) return;
                        stream_endpoint->state = AVDTP_STREAM_ENDPOINT_OPENED;
                        stream_endpoint->connection = connection;
                        stream_endpoint->l2cap_media_cid = l2cap_event_channel_opened_get_local_cid(packet);
                        printf(" -> AVDTP_STREAM_ENDPOINT_OPENED, stream endpoint %p, connection %p\n", stream_endpoint, connection);
                        avdtp_streaming_emit_connection_established(context->avdtp_callback, stream_endpoint->l2cap_media_cid, 0);
                        break;
                    }
                    break;
                case L2CAP_EVENT_CHANNEL_CLOSED:
                    local_cid = l2cap_event_channel_closed_get_local_cid(packet);
                    if (stream_endpoint->l2cap_media_cid == local_cid){
                        stream_endpoint->l2cap_media_cid = 0;
                        printf(" -> L2CAP_EVENT_CHANNEL_CLOSED: AVDTP_STREAM_ENDPOINT_IDLE\n");
                        stream_endpoint->state = AVDTP_STREAM_ENDPOINT_IDLE;
                        stream_endpoint->acceptor_config_state = AVDTP_ACCEPTOR_STREAM_CONFIG_IDLE;
                        stream_endpoint->initiator_config_state = AVDTP_INITIATOR_STREAM_CONFIG_IDLE;
                        stream_endpoint->remote_seps_num = 0;
                        memset(stream_endpoint->remote_seps, 0, sizeof(avdtp_sep_t)*MAX_NUM_SEPS);
                        stream_endpoint->remote_sep_index = 0;
                        break;
                    }
                    if (stream_endpoint->l2cap_recovery_cid == local_cid){
                        log_info(" -> L2CAP_EVENT_CHANNEL_CLOSED recovery cid 0x%0x", local_cid);
                        stream_endpoint->l2cap_recovery_cid = 0;
                        break;
                    }

                    if (stream_endpoint->l2cap_reporting_cid == local_cid){
                        log_info("L2CAP_EVENT_CHANNEL_CLOSED reporting cid 0x%0x", local_cid);
                        stream_endpoint->l2cap_reporting_cid = 0;
                        break;
                    }
                    break;
                default:
                    break;
            }
            break;
        default:
            break;
    }
}

void avdtp_packet_handler(uint8_t packet_type, uint16_t channel, uint8_t *packet, uint16_t size, avdtp_context_t * context){
    bd_addr_t event_addr;
    hci_con_handle_t con_handle;
    uint16_t psm;
    uint16_t local_cid;
    avdtp_stream_endpoint_t * stream_endpoint = NULL;
    avdtp_connection_t * connection = NULL;
    btstack_linked_list_t * avdtp_connections = &context->connections;
    btstack_linked_list_t * stream_endpoints =  &context->stream_endpoints;
    handle_media_data = context->handle_media_data;
    // printf("avdtp_packet_handler packet type %02x, event %02x \n", packet_type, hci_event_packet_get_type(packet));
    switch (packet_type) {
        case L2CAP_DATA_PACKET:
            connection = avdtp_connection_for_l2cap_signaling_cid(channel, context);
            if (connection){
                handle_l2cap_data_packet_for_signaling_connection(connection, packet, size, context);
                break;
            }

            stream_endpoint = avdtp_stream_endpoint_for_l2cap_cid(channel, context);
            if (!stream_endpoint){
                if (!connection) break;
                handle_l2cap_data_packet_for_signaling_connection(connection, packet, size, context);
                break;
            }

            if (channel == stream_endpoint->connection->l2cap_signaling_cid){
                stream_endpoint_state_machine(stream_endpoint->connection, stream_endpoint, L2CAP_DATA_PACKET, 0, packet, size, context);
                break;
            }

            if (channel == stream_endpoint->l2cap_media_cid){
                (*handle_media_data)(stream_endpoint, packet, size);
                break;
            }

            if (channel == stream_endpoint->l2cap_reporting_cid){
                // TODO
                printf("L2CAP_DATA_PACKET for reporting: NOT IMPLEMENTED\n");
            } else if (channel == stream_endpoint->l2cap_recovery_cid){
                // TODO
                printf("L2CAP_DATA_PACKET for recovery: NOT IMPLEMENTED\n");
            } else {
                log_error("avdtp packet handler L2CAP_DATA_PACKET: local cid 0x%02x not found", channel);
            }
            break;

        case HCI_EVENT_PACKET:
            switch (hci_event_packet_get_type(packet)) {
                case L2CAP_EVENT_INCOMING_CONNECTION:
                    l2cap_event_incoming_connection_get_address(packet, event_addr);
                    local_cid = l2cap_event_incoming_connection_get_local_cid(packet);

                    connection = avdtp_connection_for_bd_addr(event_addr, context);
                    if (!connection){
                        connection = avdtp_create_connection(event_addr, context);
                        connection->state = AVDTP_SIGNALING_CONNECTION_W4_L2CAP_CONNECTED;
                        l2cap_accept_connection(local_cid);
                        break;
                    }

                    stream_endpoint = avdtp_stream_endpoint_for_seid(connection->query_seid, context);
                    if (!stream_endpoint) {
                        printf("L2CAP_EVENT_INCOMING_CONNECTION no streamendpoint found for seid %d\n", connection->query_seid);
                        break;
                    }

                    if (stream_endpoint->l2cap_media_cid == 0){
                        if (stream_endpoint->state != AVDTP_STREAM_ENDPOINT_W4_L2CAP_FOR_MEDIA_CONNECTED) break;
                        l2cap_accept_connection(local_cid);
                        break;
                    }
                    break;

                case L2CAP_EVENT_CHANNEL_OPENED:
                    // inform about new l2cap connection
                    l2cap_event_channel_opened_get_address(packet, event_addr);
                    if (l2cap_event_channel_opened_get_status(packet)){
                        log_error("L2CAP connection to connection %s failed. status code 0x%02x",
                            bd_addr_to_str(event_addr), l2cap_event_channel_opened_get_status(packet));
                        break;
                    }
                    psm = l2cap_event_channel_opened_get_psm(packet);
                    if (psm != BLUETOOTH_PROTOCOL_AVDTP){
                        log_error("unexpected PSM - Not implemented yet, avdtp sink: L2CAP_EVENT_CHANNEL_OPENED");
                        return;
                    }

                    con_handle = l2cap_event_channel_opened_get_handle(packet);
                    local_cid = l2cap_event_channel_opened_get_local_cid(packet);

                    // printf("L2CAP_EVENT_CHANNEL_OPENED: Channel successfully opened: %s, handle 0x%02x, psm 0x%02x, local cid 0x%02x, remote cid 0x%02x\n",
                    //        bd_addr_to_str(event_addr), con_handle, psm, local_cid,  l2cap_event_channel_opened_get_remote_cid(packet));

                    if (psm != BLUETOOTH_PROTOCOL_AVDTP) break;

                    connection = avdtp_connection_for_bd_addr(event_addr, context);
                    if (!connection) break;

                    if (connection->l2cap_signaling_cid == 0) {
                        if (connection->state != AVDTP_SIGNALING_CONNECTION_W4_L2CAP_CONNECTED) break;
                        connection->l2cap_signaling_cid = local_cid;
                        connection->con_handle = con_handle;
                        connection->query_seid = 0;
                        connection->state = AVDTP_SIGNALING_CONNECTION_OPENED;
                        printf(" -> AVDTP_SIGNALING_CONNECTION_OPENED, connection %p\n", connection);
                        avdtp_signaling_emit_connection_established(context->avdtp_callback, con_handle, event_addr, 0);
                        break;
                    }

                    stream_endpoint = avdtp_stream_endpoint_for_seid(connection->query_seid, context);
                    if (!stream_endpoint){
                        printf("L2CAP_EVENT_CHANNEL_OPENED: stream_endpoint not found");
                        return;
                    }
                    stream_endpoint_state_machine(connection, stream_endpoint, HCI_EVENT_PACKET, L2CAP_EVENT_CHANNEL_OPENED, packet, size, context);
                    break;

                case L2CAP_EVENT_CHANNEL_CLOSED:
                    // data: event (8), len(8), channel (16)
                    local_cid = l2cap_event_channel_closed_get_local_cid(packet);
                    connection = avdtp_connection_for_l2cap_signaling_cid(local_cid, context);
                    printf(" -> L2CAP_EVENT_CHANNEL_CLOSED signaling cid 0x%0x\n", local_cid);

                    if (connection){
                        printf(" -> AVDTP_STREAM_ENDPOINT_IDLE, connection closed\n");
                        btstack_linked_list_remove(avdtp_connections, (btstack_linked_item_t*) connection);
                        btstack_linked_list_iterator_t it;
                        btstack_linked_list_iterator_init(&it, stream_endpoints);
                        while (btstack_linked_list_iterator_has_next(&it)){
                            avdtp_stream_endpoint_t * _stream_endpoint = (avdtp_stream_endpoint_t *)btstack_linked_list_iterator_next(&it);
                            avdtp_initialize_stream_endpoint(_stream_endpoint);
                        }
                        break;
                    }

                    stream_endpoint = avdtp_stream_endpoint_for_l2cap_cid(local_cid, context);
                    if (!stream_endpoint) return;

                    stream_endpoint_state_machine(connection, stream_endpoint, HCI_EVENT_PACKET, L2CAP_EVENT_CHANNEL_CLOSED, packet, size, context);
                    break;

                case HCI_EVENT_DISCONNECTION_COMPLETE:
                    break;

                case L2CAP_EVENT_CAN_SEND_NOW:
                    connection = avdtp_connection_for_l2cap_signaling_cid(channel, context);
                    if (!connection) {
                        stream_endpoint = avdtp_stream_endpoint_for_l2cap_cid(channel, context);
                        if (!stream_endpoint->connection) break;
                        if (stream_endpoint->state == AVDTP_STREAM_ENDPOINT_STREAMING_W2_SEND){
                            stream_endpoint->state = AVDTP_STREAM_ENDPOINT_STREAMING;
                            //send sbc
                            uint8_t  rtp_version = 2;
                            uint8_t  padding = 0;
                            uint8_t  extension = 0;
                            uint8_t  csrc_count = 0;
                            uint8_t  marker = 0;
                            uint8_t  payload_type = 0x60;
                            uint16_t sequence_number = stream_endpoint->sequence_number;
                            uint32_t timestamp = btstack_run_loop_get_time_ms();
                            uint32_t ssrc = 0x11223344;

                            // rtp header (min size 12B)
                            int pos = 0;
                            int mtu = l2cap_get_remote_mtu_for_local_cid(stream_endpoint->l2cap_media_cid);

                            uint8_t media_packet[mtu];
                            media_packet[pos++] = (rtp_version << 6) | (padding << 5) | (extension << 4) | csrc_count;
                            media_packet[pos++] = (marker << 1) | payload_type;
                            big_endian_store_16(media_packet, pos, sequence_number);
                            pos += 2;
                            big_endian_store_32(media_packet, pos, timestamp);
                            pos += 4;
                            big_endian_store_32(media_packet, pos, ssrc); // only used for multicast
                            pos += 4;

                            // media payload
                            // sbc_header (size 1B)
                            uint8_t sbc_header_index = pos;
                            pos++;
                            uint8_t fragmentation = 0;
                            uint8_t starting_packet = 0; // set to 1 for the first packet of a fragmented SBC frame
                            uint8_t last_packet = 0;     // set to 1 for the last packet of a fragmented SBC frame
                            uint8_t num_frames = 0;

                            uint32_t total_sbc_bytes_read = 0;
                            uint8_t  sbc_frame_size = 0;
                            // payload
                            while (mtu - 13 - total_sbc_bytes_read >= 120 && btstack_ring_buffer_bytes_available(&stream_endpoint->sbc_ring_buffer)){
                                uint32_t number_of_bytes_read = 0;
                                btstack_ring_buffer_read(&stream_endpoint->sbc_ring_buffer, &sbc_frame_size, 1, &number_of_bytes_read);
                                btstack_ring_buffer_read(&stream_endpoint->sbc_ring_buffer, media_packet + pos, sbc_frame_size, &number_of_bytes_read);
                                pos += sbc_frame_size;
                                total_sbc_bytes_read += sbc_frame_size;
                                num_frames++;
                                // printf("send sbc frame: timestamp %d, seq. nr %d\n", timestamp, stream_endpoint->sequence_number);
                            }
                            media_packet[sbc_header_index] =  (fragmentation << 7) | (starting_packet << 6) | (last_packet << 5) | num_frames;
                            stream_endpoint->sequence_number++;
                            l2cap_send(stream_endpoint->l2cap_media_cid, media_packet, pos);
                            if (btstack_ring_buffer_bytes_available(&stream_endpoint->sbc_ring_buffer)){
                                stream_endpoint->state = AVDTP_STREAM_ENDPOINT_STREAMING_W2_SEND;
                                l2cap_request_can_send_now_event(stream_endpoint->l2cap_media_cid);
                            }
                        }
                        connection = stream_endpoint->connection;
                    }
                    avdtp_handle_can_send_now(connection, channel, context);
                    break;
                default:
                    printf("unknown HCI event type %02x\n", hci_event_packet_get_type(packet));
                    break;
            }
            break;

        default:
            // other packet type
            break;
    }
}

void avdtp_disconnect(uint16_t con_handle, avdtp_context_t * context){
    avdtp_connection_t * connection = avdtp_connection_for_con_handle(con_handle, context);
    if (!connection) return;
    if (connection->state == AVDTP_SIGNALING_CONNECTION_IDLE) return;
    if (connection->state == AVDTP_SIGNALING_CONNECTION_W4_L2CAP_DISCONNECTED) return;

    connection->disconnect = 1;
    avdtp_request_can_send_now_self(connection, connection->l2cap_signaling_cid);
}

void avdtp_open_stream(uint16_t con_handle, uint8_t acp_seid, avdtp_context_t * context){
    avdtp_connection_t * connection = avdtp_connection_for_con_handle(con_handle, context);
    if (!connection){
        printf("avdtp_media_connect: no connection for handle 0x%02x found\n", con_handle);
        return;
    }

    if (connection->state != AVDTP_SIGNALING_CONNECTION_OPENED) {
        printf("avdtp_media_connect: wrong connection state %d\n", connection->state);
        return;
    }

    avdtp_stream_endpoint_t * stream_endpoint = avdtp_stream_endpoint_associated_with_acp_seid(acp_seid, context);
    if (!stream_endpoint) {
        printf("avdtp_media_connect: no stream_endpoint with acp seid %d found\n", acp_seid);
        return;
    }

    if (stream_endpoint->state < AVDTP_STREAM_ENDPOINT_CONFIGURED) return;
    if (stream_endpoint->remote_sep_index == 0xFF) return;

    connection->initiator_transaction_label++;
    connection->acp_seid = acp_seid;
    connection->int_seid = stream_endpoint->sep.seid;
    stream_endpoint->initiator_config_state = AVDTP_INITIATOR_W2_OPEN_STREAM;
    stream_endpoint->state = AVDTP_STREAM_ENDPOINT_W2_REQUEST_OPEN_STREAM;
    avdtp_request_can_send_now_initiator(connection, connection->l2cap_signaling_cid);
}

void avdtp_start_stream(uint16_t con_handle, uint8_t acp_seid, avdtp_context_t * context){
    avdtp_connection_t * connection = avdtp_connection_for_con_handle(con_handle, context);
    if (!connection){
        printf("avdtp_media_connect: no connection for handle 0x%02x found\n", con_handle);
        return;
    }

    if (connection->state != AVDTP_SIGNALING_CONNECTION_OPENED) {
        printf("avdtp_media_connect: wrong connection state %d\n", connection->state);
        return;
    }

    avdtp_stream_endpoint_t * stream_endpoint = avdtp_stream_endpoint_associated_with_acp_seid(acp_seid, context);
    if (!stream_endpoint) {
        printf("avdtp_media_connect: no stream_endpoint with acp_seid %d found\n", acp_seid);
        return;
    }
    if (stream_endpoint->remote_sep_index == 0xFF) return;
    if (stream_endpoint->state < AVDTP_STREAM_ENDPOINT_OPENED) return;
    connection->initiator_transaction_label++;
    connection->acp_seid = acp_seid;
    connection->int_seid = stream_endpoint->sep.seid;
    stream_endpoint->initiator_config_state = AVDTP_INITIATOR_W2_STREAMING_START;
    avdtp_request_can_send_now_initiator(connection, connection->l2cap_signaling_cid);
}

void avdtp_stop_stream(uint16_t con_handle, uint8_t acp_seid, avdtp_context_t * context){
    avdtp_connection_t * connection = avdtp_connection_for_con_handle(con_handle, context);
    if (!connection){
        printf("avdtp_stop_stream: no connection for handle 0x%02x found\n", con_handle);
        return;
    }
    if (connection->state != AVDTP_SIGNALING_CONNECTION_OPENED) {
        printf("avdtp_stop_stream: wrong connection state %d\n", connection->state);
        return;
    }

    avdtp_stream_endpoint_t * stream_endpoint = avdtp_stream_endpoint_associated_with_acp_seid(acp_seid, context);
    if (!stream_endpoint) {
        printf("avdtp_stop_stream: no stream_endpoint with acp seid %d found\n", acp_seid);
        return;
    }
    if (stream_endpoint->remote_sep_index == 0xFF) return;
    switch (stream_endpoint->state){
        case AVDTP_STREAM_ENDPOINT_OPENED:
        case AVDTP_STREAM_ENDPOINT_STREAMING:
            printf(" AVDTP_INITIATOR_W2_STREAMING_STOP \n");
            connection->initiator_transaction_label++;
            connection->acp_seid = acp_seid;
            connection->int_seid = stream_endpoint->sep.seid;
            stream_endpoint->initiator_config_state = AVDTP_INITIATOR_W2_STREAMING_STOP;
            avdtp_request_can_send_now_initiator(connection, connection->l2cap_signaling_cid);
            break;
        default:
            break;
    }
}

void avdtp_abort_stream(uint16_t con_handle, uint8_t acp_seid, avdtp_context_t * context){
    avdtp_connection_t * connection = avdtp_connection_for_con_handle(con_handle, context);
    if (!connection){
        printf("avdtp_abort_stream: no connection for handle 0x%02x found\n", con_handle);
        return;
    }

    if (connection->state != AVDTP_SIGNALING_CONNECTION_OPENED) {
        printf("avdtp_abort_stream: wrong connection state %d\n", connection->state);
        return;
    }

    avdtp_stream_endpoint_t * stream_endpoint = avdtp_stream_endpoint_associated_with_acp_seid(acp_seid, context);
    if (!stream_endpoint) {
        printf("avdtp_abort_stream: no stream_endpoint for seid %d found\n", acp_seid);
        return;
    }
    if (stream_endpoint->remote_sep_index == 0xFF) return;
    switch (stream_endpoint->state){
        case AVDTP_STREAM_ENDPOINT_CONFIGURED:
        case AVDTP_STREAM_ENDPOINT_CLOSING:
        case AVDTP_STREAM_ENDPOINT_OPENED:
        case AVDTP_STREAM_ENDPOINT_STREAMING:
            printf(" AVDTP_INITIATOR_W2_STREAMING_ABORT \n");
            connection->initiator_transaction_label++;
            connection->acp_seid = acp_seid;
            connection->int_seid = stream_endpoint->sep.seid;
            stream_endpoint->initiator_config_state = AVDTP_INITIATOR_W2_STREAMING_ABORT;
            avdtp_request_can_send_now_initiator(connection, connection->l2cap_signaling_cid);
            break;
        default:
            break;
    }
}

void avdtp_discover_stream_endpoints(uint16_t con_handle, avdtp_context_t * context){
    avdtp_connection_t * connection = avdtp_connection_for_con_handle(con_handle, context);
    if (!connection){
        printf("avdtp_discover_stream_endpoints: no connection for handle 0x%02x found\n", con_handle);
        return;
    }
    if (connection->state != AVDTP_SIGNALING_CONNECTION_OPENED) return;

    switch (connection->initiator_connection_state){
        case AVDTP_SIGNALING_CONNECTION_INITIATOR_IDLE:
            connection->initiator_transaction_label++;
            connection->initiator_connection_state = AVDTP_SIGNALING_CONNECTION_INITIATOR_W2_DISCOVER_SEPS;
            avdtp_request_can_send_now_initiator(connection, connection->l2cap_signaling_cid);
            break;
        default:
            printf("avdtp_discover_stream_endpoints: wrong state\n");
            break;
    }
}


void avdtp_get_capabilities(uint16_t con_handle, uint8_t acp_seid, avdtp_context_t * context){
    avdtp_connection_t * connection = avdtp_connection_for_con_handle(con_handle, context);
    if (!connection){
        printf("avdtp_get_capabilities: no connection for handle 0x%02x found\n", con_handle);
        return;
    }
    if (connection->state != AVDTP_SIGNALING_CONNECTION_OPENED) return;
    if (connection->initiator_connection_state != AVDTP_SIGNALING_CONNECTION_INITIATOR_IDLE) return;
    connection->initiator_transaction_label++;
    connection->initiator_connection_state = AVDTP_SIGNALING_CONNECTION_INITIATOR_W2_GET_CAPABILITIES;
    connection->acp_seid = acp_seid;
    avdtp_request_can_send_now_initiator(connection, connection->l2cap_signaling_cid);
}


void avdtp_get_all_capabilities(uint16_t con_handle, uint8_t acp_seid, avdtp_context_t * context){
    avdtp_connection_t * connection = avdtp_connection_for_con_handle(con_handle, context);
    if (!connection){
        printf("avdtp_get_all_capabilities: no connection for handle 0x%02x found\n", con_handle);
        return;
    }
    if (connection->state != AVDTP_SIGNALING_CONNECTION_OPENED) return;
    if (connection->initiator_connection_state != AVDTP_SIGNALING_CONNECTION_INITIATOR_IDLE) return;
    connection->initiator_transaction_label++;
    connection->initiator_connection_state = AVDTP_SIGNALING_CONNECTION_INITIATOR_W2_GET_ALL_CAPABILITIES;
    connection->acp_seid = acp_seid;
    avdtp_request_can_send_now_initiator(connection, connection->l2cap_signaling_cid);
}

void avdtp_get_configuration(uint16_t con_handle, uint8_t acp_seid, avdtp_context_t * context){
    avdtp_connection_t * connection = avdtp_connection_for_con_handle(con_handle, context);
    if (!connection){
        printf("avdtp_get_configuration: no connection for handle 0x%02x found\n", con_handle);
        return;
    }
    if (connection->state != AVDTP_SIGNALING_CONNECTION_OPENED) return;
    if (connection->initiator_connection_state != AVDTP_SIGNALING_CONNECTION_INITIATOR_IDLE) return;
    connection->initiator_transaction_label++;
    connection->initiator_connection_state = AVDTP_SIGNALING_CONNECTION_INITIATOR_W2_GET_CONFIGURATION;
    connection->acp_seid = acp_seid;
    avdtp_request_can_send_now_initiator(connection, connection->l2cap_signaling_cid);
}

void avdtp_set_configuration(uint16_t con_handle, uint8_t int_seid, uint8_t acp_seid, uint16_t configured_services_bitmap, avdtp_capabilities_t configuration, avdtp_context_t * context){
    avdtp_connection_t * connection = avdtp_connection_for_con_handle(con_handle, context);
    if (!connection){
        log_error("avdtp_set_configuration: no connection for handle 0x%02x found\n", con_handle);
        return;
    }
    if (connection->state != AVDTP_SIGNALING_CONNECTION_OPENED) return;
    if (connection->initiator_connection_state != AVDTP_SIGNALING_CONNECTION_INITIATOR_IDLE) return;

    avdtp_stream_endpoint_t * stream_endpoint = avdtp_stream_endpoint_for_seid(int_seid, context);
    if (!stream_endpoint) {
        log_error("avdtp_set_configuration: no initiator stream endpoint for seid %d\n", int_seid);
        return;
    }
    // printf("avdtp_set_configuration int seid %d, acp seid %d\n", int_seid, acp_seid);

    connection->initiator_transaction_label++;
    connection->acp_seid = acp_seid;
    connection->int_seid = int_seid;
    connection->remote_capabilities_bitmap = configured_services_bitmap;
    connection->remote_capabilities = configuration;
    stream_endpoint->initiator_config_state = AVDTP_INITIATOR_W2_SET_CONFIGURATION;
    avdtp_request_can_send_now_initiator(connection, connection->l2cap_signaling_cid);
}

void avdtp_reconfigure(uint16_t con_handle, uint8_t acp_seid, uint16_t configured_services_bitmap, avdtp_capabilities_t configuration, avdtp_context_t * context){
    avdtp_connection_t * connection = avdtp_connection_for_con_handle(con_handle, context);
    if (!connection){
        printf("avdtp_reconfigure: no connection for handle 0x%02x found\n", con_handle);
        return;
    }
    //TODO: if opened only app capabilities, enable reconfigure for not opened
    if (connection->state < AVDTP_SIGNALING_CONNECTION_OPENED) return;
    if (connection->initiator_connection_state != AVDTP_SIGNALING_CONNECTION_INITIATOR_IDLE) return;
    avdtp_stream_endpoint_t * stream_endpoint = avdtp_stream_endpoint_associated_with_acp_seid(acp_seid, context);
    if (!stream_endpoint) return;
    if (stream_endpoint->remote_sep_index == 0xFF) return;
    connection->initiator_transaction_label++;
    connection->acp_seid = acp_seid;
    connection->int_seid = stream_endpoint->sep.seid;
    connection->remote_capabilities_bitmap = configured_services_bitmap;
    connection->remote_capabilities = configuration;
    stream_endpoint->initiator_config_state = AVDTP_INITIATOR_W2_RECONFIGURE_STREAM_WITH_SEID;
    avdtp_request_can_send_now_initiator(connection, connection->l2cap_signaling_cid);
}

void avdtp_suspend(uint16_t con_handle, uint8_t acp_seid, avdtp_context_t * context){
    avdtp_connection_t * connection = avdtp_connection_for_con_handle(con_handle, context);
    if (!connection){
        printf("avdtp_suspend: no connection for handle 0x%02x found\n", con_handle);
        return;
    }
    if (connection->state != AVDTP_SIGNALING_CONNECTION_OPENED) return;
    if (connection->initiator_connection_state != AVDTP_SIGNALING_CONNECTION_INITIATOR_IDLE) return;
    avdtp_stream_endpoint_t * stream_endpoint = avdtp_stream_endpoint_associated_with_acp_seid(acp_seid, context);
    if (!stream_endpoint) return;
    if (stream_endpoint->remote_sep_index == 0xFF) return;
    connection->initiator_transaction_label++;
    connection->acp_seid = acp_seid;
    connection->int_seid = stream_endpoint->sep.seid;
    stream_endpoint->initiator_config_state = AVDTP_INITIATOR_W2_SUSPEND_STREAM_WITH_SEID;
    avdtp_request_can_send_now_initiator(connection, connection->l2cap_signaling_cid);
}