xref: /btstack/src/classic/avdtp.c (revision c70720c67056dadfbbef227c89dcb22a37fba036)

/*
 * 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 <string.h>

#include "bluetooth_psm.h"
#include "bluetooth_sdp.h"
#include "btstack_debug.h"
#include "btstack_event.h"
#include "btstack_memory.h"
#include "classic/avdtp.h"
#include "classic/avdtp_util.h"
#include "classic/avdtp_acceptor.h"
#include "classic/avdtp_initiator.h"
#include "classic/avdtp_util.h"
#include "classic/sdp_client.h"
#include "classic/sdp_util.h"

btstack_linked_list_t stream_endpoints;

static bool l2cap_registered;

static btstack_packet_handler_t avdtp_source_callback;
static btstack_packet_handler_t avdtp_sink_callback;
static btstack_context_callback_registration_t avdtp_handle_sdp_client_query_request;
static uint8_t (*avdtp_media_config_validator)(const avdtp_stream_endpoint_t * stream_endpoint, const uint8_t * event, uint16_t size);

static uint16_t sdp_query_context_avdtp_cid = 0;

static uint16_t stream_endpoints_id_counter = 0;

static btstack_linked_list_t connections;
static uint16_t transaction_id_counter = 0;

static int record_id;
static uint8_t attribute_value[45];
static const unsigned int attribute_value_buffer_size = sizeof(attribute_value);

static void (*avdtp_sink_handle_media_data)(uint8_t local_seid, uint8_t *packet, uint16_t size);

static uint16_t avdtp_cid_counter = 0;

static void avdtp_handle_sdp_client_query_result(uint8_t packet_type, uint16_t channel, uint8_t *packet, uint16_t size);

btstack_packet_handler_t
avdtp_packet_handler_for_stream_endpoint(const avdtp_stream_endpoint_t *stream_endpoint) {
    return (stream_endpoint->sep.type == AVDTP_SOURCE) ? avdtp_source_callback : avdtp_sink_callback;
}

void avdtp_emit_sink_and_source(uint8_t * packet, uint16_t size){
    if (avdtp_source_callback != NULL){
        (*avdtp_source_callback)(HCI_EVENT_PACKET, 0, packet, size);
    }
    if (avdtp_sink_callback != NULL){
        (*avdtp_sink_callback)(HCI_EVENT_PACKET, 0, packet, size);
    }
}

void avdtp_emit_source(uint8_t * packet, uint16_t size){
    if (avdtp_source_callback != NULL){
        (*avdtp_source_callback)(HCI_EVENT_PACKET, 0, packet, size);
    }
}

btstack_linked_list_t * avdtp_get_stream_endpoints(void){
    return &stream_endpoints;
}

btstack_linked_list_t * avdtp_get_connections(void){
    return &connections;
}

avdtp_connection_t * avdtp_get_connection_for_bd_addr(bd_addr_t addr){
    btstack_linked_list_iterator_t it;
    btstack_linked_list_iterator_init(&it, &connections);
    while (btstack_linked_list_iterator_has_next(&it)){
        avdtp_connection_t * connection = (avdtp_connection_t *)btstack_linked_list_iterator_next(&it);
        if (memcmp(addr, connection->remote_addr, 6) != 0) continue;
        return connection;
    }
    return NULL;
}

 avdtp_connection_t * avdtp_get_connection_for_avdtp_cid(uint16_t avdtp_cid){
    btstack_linked_list_iterator_t it;
    btstack_linked_list_iterator_init(&it, &connections);
    while (btstack_linked_list_iterator_has_next(&it)){
        avdtp_connection_t * connection = (avdtp_connection_t *)btstack_linked_list_iterator_next(&it);
        if (connection->avdtp_cid != avdtp_cid) continue;
        return connection;
    }
    return NULL;
}


avdtp_stream_endpoint_t * avdtp_get_stream_endpoint_for_seid(uint16_t seid){
    btstack_linked_list_iterator_t it;
    btstack_linked_list_iterator_init(&it, avdtp_get_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->sep.seid == seid){
            return stream_endpoint;
        }
    }
    return NULL;
}

avdtp_stream_endpoint_t * avdtp_get_source_stream_endpoint_for_media_codec(avdtp_media_codec_type_t codec_type){
    btstack_linked_list_iterator_t it;
    btstack_linked_list_iterator_init(&it, avdtp_get_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->sep.type != AVDTP_SOURCE) continue;
        if (stream_endpoint->sep.media_type != AVDTP_AUDIO) continue;
        if (stream_endpoint->sep.capabilities.media_codec.media_codec_type != codec_type) continue;
        if (stream_endpoint->sep.in_use) continue;
        return stream_endpoint;
    }
    return NULL;
}

avdtp_stream_endpoint_t * avdtp_get_source_stream_endpoint_for_media_codec_other(uint32_t vendor_id, uint16_t codec_id){
    btstack_linked_list_iterator_t it;
    btstack_linked_list_iterator_init(&it, avdtp_get_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->sep.type != AVDTP_SOURCE) continue;
        if (stream_endpoint->sep.media_type != AVDTP_AUDIO) continue;
        if (stream_endpoint->sep.in_use) continue;
        if (stream_endpoint->sep.capabilities.media_codec.media_codec_type != AVDTP_CODEC_NON_A2DP) continue;
        if (stream_endpoint->sep.capabilities.media_codec.media_codec_information_len < 6) continue;
        if (little_endian_read_32(stream_endpoint->sep.capabilities.media_codec.media_codec_information, 0) != vendor_id) continue;
        if (little_endian_read_16(stream_endpoint->sep.capabilities.media_codec.media_codec_information, 4) != codec_id) continue;
        return stream_endpoint;
    }
    return NULL;
}


avdtp_connection_t * avdtp_get_connection_for_l2cap_signaling_cid(uint16_t l2cap_cid){
    btstack_linked_list_iterator_t it;
    btstack_linked_list_iterator_init(&it, &connections);
    while (btstack_linked_list_iterator_has_next(&it)){
        avdtp_connection_t * connection = (avdtp_connection_t *)btstack_linked_list_iterator_next(&it);
        if (connection->l2cap_signaling_cid != l2cap_cid) continue;
        return connection;
    }
    return NULL;
}

static avdtp_stream_endpoint_t * avdtp_get_stream_endpoint_for_l2cap_cid(uint16_t l2cap_cid){
    btstack_linked_list_iterator_t it;
    btstack_linked_list_iterator_init(&it, avdtp_get_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->l2cap_media_cid == l2cap_cid){
            return stream_endpoint;
        }
        if (stream_endpoint->l2cap_reporting_cid == l2cap_cid){
            return stream_endpoint;
        }
        if (stream_endpoint->l2cap_recovery_cid == l2cap_cid){
            return stream_endpoint;
        }
    }
    return NULL;
}

static avdtp_stream_endpoint_t * avdtp_get_stream_endpoint_for_signaling_cid(uint16_t l2cap_cid){
    btstack_linked_list_iterator_t it;
    btstack_linked_list_iterator_init(&it, avdtp_get_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){
            if (stream_endpoint->connection->l2cap_signaling_cid == l2cap_cid){
                return stream_endpoint;
            }
        }
    }
    return NULL;
}

uint16_t avdtp_get_next_transaction_label(void){
    transaction_id_counter++;
    if (transaction_id_counter == 16){
        transaction_id_counter = 1;
    }
    return transaction_id_counter;
}

static avdtp_connection_t * avdtp_create_connection(bd_addr_t remote_addr, uint16_t cid){
    avdtp_connection_t * connection = btstack_memory_avdtp_connection_get();
    if (!connection){
        log_error("Not enough memory to create connection");
        return NULL;
    }
    connection->state = AVDTP_SIGNALING_CONNECTION_IDLE;
    connection->initiator_transaction_label = avdtp_get_next_transaction_label();
    connection->configuration_state = AVDTP_CONFIGURATION_STATE_IDLE;
    connection->a2dp_source_discover_seps = false;
    connection->avdtp_cid = cid;
    (void)memcpy(connection->remote_addr, remote_addr, 6);

    btstack_linked_list_add(&connections, (btstack_linked_item_t *) connection);
    return connection;
}

static uint16_t avdtp_get_next_cid(void){
    if (avdtp_cid_counter == 0xffff) {
        avdtp_cid_counter = 1;
    } else {
        avdtp_cid_counter++;
    }
    return avdtp_cid_counter;
}

static uint16_t avdtp_get_next_local_seid(void){
    if (stream_endpoints_id_counter == 0xffff) {
        stream_endpoints_id_counter = 1;
    } else {
        stream_endpoints_id_counter++;
    }
    return stream_endpoints_id_counter;
}

static void avdtp_handle_start_sdp_client_query(void * context){
    UNUSED(context);

    btstack_linked_list_iterator_t it;
    btstack_linked_list_iterator_init(&it, &connections);
    while (btstack_linked_list_iterator_has_next(&it)){
        avdtp_connection_t * connection = (avdtp_connection_t *)btstack_linked_list_iterator_next(&it);

        switch (connection->state){
            case AVDTP_SIGNALING_W2_SEND_SDP_QUERY_FOR_REMOTE_SOURCE:
                connection->state = AVDTP_SIGNALING_W4_SDP_QUERY_FOR_REMOTE_SOURCE_COMPLETE;
                break;
            case AVDTP_SIGNALING_W2_SEND_SDP_QUERY_FOR_REMOTE_SINK:
                connection->state = AVDTP_SIGNALING_W4_SDP_QUERY_FOR_REMOTE_SINK_COMPLETE;
                break;
            case AVDTP_SIGNALING_CONNECTION_OPENED:
                if (connection->initiator_connection_state != AVDTP_SIGNALING_CONNECTION_INITIATOR_W2_SEND_SDP_QUERY_THEN_GET_ALL_CAPABILITIES) continue;
                connection->initiator_connection_state = AVDTP_SIGNALING_CONNECTION_INITIATOR_W4_SDP_QUERY_COMPLETE_THEN_GET_ALL_CAPABILITIES;
                break;
            default:
                continue;
        }
        sdp_query_context_avdtp_cid = connection->avdtp_cid;
        record_id = -1;
        sdp_client_query_uuid16(&avdtp_handle_sdp_client_query_result, (uint8_t *) connection->remote_addr, BLUETOOTH_PROTOCOL_AVDTP);
        return;
    }
}

uint8_t avdtp_connect(bd_addr_t remote, avdtp_role_t role, uint16_t * avdtp_cid){
    avdtp_connection_t * connection = avdtp_get_connection_for_bd_addr(remote);
    if (connection){
        return ERROR_CODE_COMMAND_DISALLOWED;
    }

    uint16_t cid = avdtp_get_next_cid();
    if (avdtp_cid != NULL) {
        *avdtp_cid = cid;
    }

    connection = avdtp_create_connection(remote, cid);
    if (!connection) return BTSTACK_MEMORY_ALLOC_FAILED;

    connection->avdtp_cid = cid;

    connection->avdtp_l2cap_psm = 0;
    connection->avdtp_version  = 0;
    connection->sink_supported = false;
    connection->source_supported = false;

    switch (role){
        case AVDTP_ROLE_SOURCE:
            connection->state = AVDTP_SIGNALING_W2_SEND_SDP_QUERY_FOR_REMOTE_SINK;
            break;
        case AVDTP_ROLE_SINK:
            connection->state = AVDTP_SIGNALING_W2_SEND_SDP_QUERY_FOR_REMOTE_SOURCE;
            break;
        default:
            btstack_assert(false);
            return ERROR_CODE_COMMAND_DISALLOWED;
    }

    avdtp_handle_sdp_client_query_request.callback = &avdtp_handle_start_sdp_client_query;
    // ignore ERROR_CODE_COMMAND_DISALLOWED because in that case, we already have requested an SDP callback
    (void) sdp_client_register_query_callback(&avdtp_handle_sdp_client_query_request);
    return ERROR_CODE_SUCCESS;
}


void avdtp_register_sink_packet_handler(btstack_packet_handler_t callback){
    btstack_assert(callback != NULL);
    avdtp_sink_callback = callback;
}

void avdtp_register_source_packet_handler(btstack_packet_handler_t callback){
    btstack_assert(callback != NULL);
    avdtp_source_callback = callback;
}

void avdtp_register_media_transport_category(avdtp_stream_endpoint_t * stream_endpoint){
    if (!stream_endpoint){
        log_error("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;
}

void avdtp_register_reporting_category(avdtp_stream_endpoint_t * stream_endpoint){
    if (!stream_endpoint){
        log_error("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("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("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("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;
    (void)memcpy(stream_endpoint->sep.capabilities.content_protection.cp_type_value,
                 cp_type_value,
                 btstack_min(cp_type_value_len, AVDTP_MAX_CONTENT_PROTECTION_TYPE_VALUE_LEN));
    stream_endpoint->sep.capabilities.content_protection.cp_type_value_len = btstack_min(cp_type_value_len, AVDTP_MAX_CONTENT_PROTECTION_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("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("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;
    stream_endpoint->sep.capabilities.media_codec.media_type = media_type;
    stream_endpoint->sep.capabilities.media_codec.media_codec_type = media_codec_type;
    // @todo should be stored in struct as const
    stream_endpoint->sep.capabilities.media_codec.media_codec_information = (uint8_t*) 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("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;
}

void avdtp_register_media_handler(void (*callback)(uint8_t local_seid, uint8_t *packet, uint16_t size)){
    avdtp_sink_handle_media_data = callback;
}

void avdtp_register_media_config_validator(uint8_t (*callback)(const avdtp_stream_endpoint_t * stream_endpoint, const uint8_t * event, uint16_t size)){
    avdtp_media_config_validator = callback;
}

uint8_t avdtp_validate_media_configuration(const avdtp_stream_endpoint_t *stream_endpoint, uint16_t avdtp_cid,
                                           uint8_t reconfigure, const adtvp_media_codec_capabilities_t *media_codec) {
    if (avdtp_media_config_validator == NULL) {
        return 0;
    }
    uint8_t event[AVDTP_MEDIA_CONFIG_OTHER_EVENT_LEN];
    uint16_t size = avdtp_setup_media_codec_config_event(event, sizeof(event), stream_endpoint, avdtp_cid, reconfigure, media_codec);
    return (*avdtp_media_config_validator)(stream_endpoint, event, size);
}

/* START: tracking can send now requests per l2cap cid */
static void avdtp_handle_can_send_now(uint16_t l2cap_cid) {

	log_debug("avdtp_packet_handler, L2CAP_EVENT_CAN_SEND_NOW l2cap_cid 0x%02x", l2cap_cid);

	// get signaling connection for l2cap cid
	avdtp_connection_t * connection = avdtp_get_connection_for_l2cap_signaling_cid(l2cap_cid);

	if (connection != NULL) {
		if (connection->wait_to_send_acceptor) {
			log_debug("call avdtp_acceptor_stream_config_subsm_run %p", connection);
			connection->wait_to_send_acceptor = false;
			avdtp_acceptor_stream_config_subsm_run(connection);
		} else if (connection->wait_to_send_initiator) {
			log_debug("call avdtp_initiator_stream_config_subsm_handle_can_send_now_signaling %p", connection);
			connection->wait_to_send_initiator = false;
			avdtp_initiator_stream_config_subsm_handle_can_send_now_signaling(connection);
		}
		bool more_to_send = connection->wait_to_send_acceptor || connection->wait_to_send_initiator;
		if (more_to_send){
			l2cap_request_can_send_now_event(l2cap_cid);
		}
		return;
	}

	// get stream endpoint connection for l2cap cid
	avdtp_stream_endpoint_t * stream_endpoint = avdtp_get_stream_endpoint_for_l2cap_cid(l2cap_cid);
	if (stream_endpoint != NULL) {
		log_debug("call avdtp_initiator_stream_config_subsm_handle_can_send_now_stream_endpoint %p", stream_endpoint);
		if (stream_endpoint->request_can_send_now) {
			stream_endpoint->request_can_send_now = false;
			avdtp_initiator_stream_config_subsm_handle_can_send_now_stream_endpoint(stream_endpoint);
		}
		if (stream_endpoint->request_can_send_now){
			l2cap_request_can_send_now_event(l2cap_cid);
		}
	}
}
/* END: tracking can send now requests per l2cap cid */


avdtp_stream_endpoint_t * avdtp_create_stream_endpoint(avdtp_sep_type_t sep_type, avdtp_media_type_t media_type){
    avdtp_stream_endpoint_t * stream_endpoint = btstack_memory_avdtp_stream_endpoint_get();
    if (!stream_endpoint){
        log_error("Not enough memory to create stream endpoint");
        return NULL;
    }
    stream_endpoint->sep.seid = avdtp_get_next_local_seid();
    stream_endpoint->sep.media_type = media_type;
    stream_endpoint->sep.type = sep_type;
    btstack_linked_list_add(avdtp_get_stream_endpoints(), (btstack_linked_item_t *) stream_endpoint);
    return stream_endpoint;
}

void avdtp_finalize_stream_endpoint(avdtp_stream_endpoint_t * stream_endpoint){
    btstack_linked_list_remove(avdtp_get_stream_endpoints(), (btstack_linked_item_t* ) stream_endpoint);
    btstack_memory_avdtp_stream_endpoint_free(stream_endpoint);
}

static void
handle_l2cap_data_packet_for_signaling_connection(avdtp_connection_t *connection, uint8_t *packet, uint16_t size) {
    if (size < 2) return;

    uint16_t offset;
    avdtp_message_type_t message_type = avdtp_get_signaling_packet_type(packet);
    switch (message_type){
        case AVDTP_CMD_MSG:
            offset = avdtp_read_signaling_header(&connection->acceptor_signaling_packet, packet, size);
            avdtp_acceptor_stream_config_subsm(connection, packet, size, offset);
            break;
        default:
            offset = avdtp_read_signaling_header(&connection->initiator_signaling_packet, packet, size);
            avdtp_initiator_stream_config_subsm(connection, packet, size, offset);
            break;
    }
}

static void avdtp_handle_sdp_client_query_attribute_value(avdtp_connection_t * connection, uint8_t *packet){
    des_iterator_t des_list_it;
    des_iterator_t prot_it;

    // Handle new SDP record
    if (sdp_event_query_attribute_byte_get_record_id(packet) != record_id) {
        record_id = sdp_event_query_attribute_byte_get_record_id(packet);
        // log_info("SDP Record: Nr: %d", record_id);
    }

    if (sdp_event_query_attribute_byte_get_attribute_length(packet) <= attribute_value_buffer_size) {
        attribute_value[sdp_event_query_attribute_byte_get_data_offset(packet)] = sdp_event_query_attribute_byte_get_data(packet);

        if ((uint16_t)(sdp_event_query_attribute_byte_get_data_offset(packet)+1) == sdp_event_query_attribute_byte_get_attribute_length(packet)) {

            switch(sdp_event_query_attribute_byte_get_attribute_id(packet)) {

                case BLUETOOTH_ATTRIBUTE_SERVICE_CLASS_ID_LIST:
                    if (de_get_element_type(attribute_value) != DE_DES) break;
                    for (des_iterator_init(&des_list_it, attribute_value); des_iterator_has_more(&des_list_it); des_iterator_next(&des_list_it)) {
                        uint8_t * element = des_iterator_get_element(&des_list_it);
                        if (de_get_element_type(element) != DE_UUID) continue;
                        uint32_t uuid = de_get_uuid32(element);
                        switch (uuid){
                            case BLUETOOTH_SERVICE_CLASS_AUDIO_SOURCE:
                                connection->source_supported = true;
                                log_info("source_supported");
                                break;
                            case BLUETOOTH_SERVICE_CLASS_AUDIO_SINK:
                                connection->sink_supported = true;
                                log_info("sink_supported");
                                break;
                            default:
                                break;
                        }
                    }
                    break;

                case BLUETOOTH_ATTRIBUTE_PROTOCOL_DESCRIPTOR_LIST:
                    // log_info("SDP Attribute: 0x%04x", sdp_event_query_attribute_byte_get_attribute_id(packet));
                    for (des_iterator_init(&des_list_it, attribute_value); des_iterator_has_more(&des_list_it); des_iterator_next(&des_list_it)) {
                        uint8_t       *des_element;
                        uint8_t       *element;
                        uint32_t       uuid;

                        if (des_iterator_get_type(&des_list_it) != DE_DES) continue;

                        des_element = des_iterator_get_element(&des_list_it);
                        des_iterator_init(&prot_it, des_element);
                        element = des_iterator_get_element(&prot_it);

                        if (de_get_element_type(element) != DE_UUID) continue;

                        uuid = de_get_uuid32(element);
                        des_iterator_next(&prot_it);
                        // we assume that the even if there are both roles supported, remote device uses the same psm and avdtp version for both
                        switch (uuid){
                            case BLUETOOTH_PROTOCOL_L2CAP:
                                if (!des_iterator_has_more(&prot_it)) continue;
                                de_element_get_uint16(des_iterator_get_element(&prot_it), &connection->avdtp_l2cap_psm);
                                break;
                            case BLUETOOTH_PROTOCOL_AVDTP:
                                if (!des_iterator_has_more(&prot_it)) continue;
                                de_element_get_uint16(des_iterator_get_element(&prot_it), &connection->avdtp_version);
                                log_info("avdtp version 0x%02x", connection->avdtp_version);
                                break;
                            default:
                                break;
                        }
                    }
                    break;

                default:
                    break;
            }
        }
    } else {
        log_error("SDP attribute value buffer size exceeded: available %d, required %d", attribute_value_buffer_size, sdp_event_query_attribute_byte_get_attribute_length(packet));
    }

}

static void avdtp_finalize_connection(avdtp_connection_t * connection){
    btstack_run_loop_remove_timer(&connection->retry_timer);
    btstack_linked_list_remove(&connections, (btstack_linked_item_t*) connection);
    btstack_memory_avdtp_connection_free(connection);
}

static void avdtp_handle_sdp_query_failed(avdtp_connection_t * connection, uint8_t status){
    switch (connection->state){
        case AVDTP_SIGNALING_W4_SDP_QUERY_FOR_REMOTE_SINK_COMPLETE:
        case AVDTP_SIGNALING_W4_SDP_QUERY_FOR_REMOTE_SOURCE_COMPLETE:
            avdtp_signaling_emit_connection_established(connection->avdtp_cid, connection->remote_addr, connection->con_handle, status);
            break;

        case AVDTP_SIGNALING_CONNECTION_OPENED:
            // SDP query failed: try query that must be supported
            connection->initiator_connection_state = AVDTP_SIGNALING_CONNECTION_INITIATOR_W2_GET_CAPABILITIES;
			avdtp_request_can_send_now_initiator(connection);
            return;

        default:
            btstack_assert(false);
            break;
    }
    avdtp_finalize_connection(connection);
    sdp_query_context_avdtp_cid = 0;
    log_info("SDP query failed with status 0x%02x.", status);
}

static void avdtp_handle_sdp_query_succeeded(avdtp_connection_t * connection){
    log_info("avdtp_handle_sdp_query_succeeded: state %d", connection->state);

    switch (connection->state){
        case AVDTP_SIGNALING_CONNECTION_OPENED:
            if (connection->avdtp_version < 0x0103){
                connection->initiator_connection_state = AVDTP_SIGNALING_CONNECTION_INITIATOR_W2_GET_CAPABILITIES;
            } else {
                connection->initiator_connection_state = AVDTP_SIGNALING_CONNECTION_INITIATOR_W2_GET_ALL_CAPABILITIES;
            }
			avdtp_request_can_send_now_initiator(connection);
            break;
        default:
            connection->state = AVDTP_SIGNALING_CONNECTION_W4_L2CAP_CONNECTED;
            l2cap_create_channel(avdtp_packet_handler, connection->remote_addr, connection->avdtp_l2cap_psm, l2cap_max_mtu(), NULL);
            break;
    }
}

static void avdtp_handle_sdp_client_query_result(uint8_t packet_type, uint16_t channel, uint8_t *packet, uint16_t size){
    UNUSED(packet_type);
    UNUSED(channel);
    UNUSED(size);

    avdtp_connection_t * connection = avdtp_get_connection_for_avdtp_cid(sdp_query_context_avdtp_cid);
    if (!connection) {
        log_error("SDP query, connection with 0x%02x cid not found", sdp_query_context_avdtp_cid);
        return;
    }

    uint8_t status = ERROR_CODE_SUCCESS;
    switch (connection->state){
        case AVDTP_SIGNALING_W4_SDP_QUERY_FOR_REMOTE_SINK_COMPLETE:
            switch (hci_event_packet_get_type(packet)){
                case SDP_EVENT_QUERY_ATTRIBUTE_VALUE:
                    avdtp_handle_sdp_client_query_attribute_value(connection, packet);
                    return;
                case SDP_EVENT_QUERY_COMPLETE:
                    status = sdp_event_query_complete_get_status(packet);
                    if (status != ERROR_CODE_SUCCESS) break;
                    if (!connection->sink_supported || (connection->avdtp_l2cap_psm == 0)) {
                        status = SDP_SERVICE_NOT_FOUND;
                        break;
                    }
                    break;
                default:
                    btstack_assert(false);
                    return;
            }
            break;
        case AVDTP_SIGNALING_W4_SDP_QUERY_FOR_REMOTE_SOURCE_COMPLETE:
            switch (hci_event_packet_get_type(packet)){
                case SDP_EVENT_QUERY_ATTRIBUTE_VALUE:
                    avdtp_handle_sdp_client_query_attribute_value(connection, packet);
                    return;
                case SDP_EVENT_QUERY_COMPLETE:
                    status = sdp_event_query_complete_get_status(packet);
                    if (status != ERROR_CODE_SUCCESS) break;
                    if (!connection->source_supported || (connection->avdtp_l2cap_psm == 0)) {
                        status = SDP_SERVICE_NOT_FOUND;
                        break;
                    }
                    break;
                default:
                    btstack_assert(false);
                    return;
            }
            break;

        case AVDTP_SIGNALING_CONNECTION_OPENED:
            switch (hci_event_packet_get_type(packet)){
                case SDP_EVENT_QUERY_ATTRIBUTE_VALUE:
                    avdtp_handle_sdp_client_query_attribute_value(connection, packet);
                    return;
                case SDP_EVENT_QUERY_COMPLETE:
                    // without suitable SDP Record, avdtp version v0.0 is assumed
                    status = sdp_event_query_complete_get_status(packet);
                    break;
                default:
                    btstack_assert(false);
                    return;
            }
            break;

        default:
            // bail out, we must have had an incoming connection in the meantime; just trigger next sdp query on complete
            if (hci_event_packet_get_type(packet) == SDP_EVENT_QUERY_COMPLETE){
                (void) sdp_client_register_query_callback(&avdtp_handle_sdp_client_query_request);
            }
            return;
    }

    if (status == ERROR_CODE_SUCCESS){
        avdtp_handle_sdp_query_succeeded(connection);
    } else {
        avdtp_handle_sdp_query_failed(connection, status);
    }

    // register the SDP Query request to check if there is another connection waiting for the query
    // ignore ERROR_CODE_COMMAND_DISALLOWED because in that case, we already have requested an SDP callback
    (void) sdp_client_register_query_callback(&avdtp_handle_sdp_client_query_request);
}

static avdtp_connection_t * avdtp_handle_incoming_connection(avdtp_connection_t * connection, bd_addr_t event_addr, hci_con_handle_t con_handle, uint16_t local_cid){
    if (connection == NULL){
        uint16_t cid = avdtp_get_next_cid();
        connection = avdtp_create_connection(event_addr, cid);
    }

    if (connection) {
        connection->state = AVDTP_SIGNALING_CONNECTION_W4_L2CAP_CONNECTED;
        connection->l2cap_signaling_cid = local_cid;
        connection->con_handle = con_handle;
        btstack_run_loop_remove_timer(&connection->retry_timer);
    }
    return connection;
}

static void avdtp_retry_timer_timeout_handler(btstack_timer_source_t * timer){
    uint16_t avdtp_cid = (uint16_t)(uintptr_t) btstack_run_loop_get_timer_context(timer);

    avdtp_connection_t * connection = avdtp_get_connection_for_avdtp_cid(avdtp_cid);
    if (connection == NULL) return;

    if (connection->state == AVDTP_SIGNALING_CONNECTION_W2_L2CAP_RETRY){
        connection->state = AVDTP_SIGNALING_CONNECTION_W4_L2CAP_CONNECTED;
        l2cap_create_channel(&avdtp_packet_handler, connection->remote_addr, connection->avdtp_l2cap_psm, l2cap_max_mtu(), NULL);
    }
}

static void avdtp_retry_timer_start(avdtp_connection_t * connection){
    btstack_run_loop_set_timer_handler(&connection->retry_timer, avdtp_retry_timer_timeout_handler);
    btstack_run_loop_set_timer_context(&connection->retry_timer, (void *)(uintptr_t)connection->avdtp_cid);

    // add some jitter/randomness to reconnect delay
    uint32_t timeout = 100 + (btstack_run_loop_get_time_ms() & 0x7F);
    btstack_run_loop_set_timer(&connection->retry_timer, timeout);
    btstack_run_loop_add_timer(&connection->retry_timer);
}

static void avdtp_handle_close_media_channel(avdtp_stream_endpoint_t * stream_endpoint){
    avdtp_connection_t * connection = stream_endpoint->connection;
    btstack_assert(connection != NULL);
    avdtp_streaming_emit_connection_released(stream_endpoint, connection->avdtp_cid, avdtp_local_seid(stream_endpoint));
    avdtp_reset_stream_endpoint(stream_endpoint);
    connection->configuration_state = AVDTP_CONFIGURATION_STATE_IDLE;
}

static void avdtp_handle_close_recovery_channel(avdtp_stream_endpoint_t * stream_endpoint){
    log_info("L2CAP_EVENT_CHANNEL_CLOSED recovery cid 0x%0x", stream_endpoint->l2cap_recovery_cid);
    stream_endpoint->l2cap_recovery_cid = 0;
}

static void avdtp_handle_close_reporting_channel(avdtp_stream_endpoint_t * stream_endpoint){
    log_info("L2CAP_EVENT_CHANNEL_CLOSED reporting cid 0x%0x", stream_endpoint->l2cap_reporting_cid);
    stream_endpoint->l2cap_reporting_cid = 0;
}


void avdtp_packet_handler(uint8_t packet_type, uint16_t channel, uint8_t *packet, uint16_t size){
    bd_addr_t event_addr;
    uint16_t psm;
    uint16_t local_cid;
    uint8_t  status;
    uint16_t l2cap_mtu;
    hci_con_handle_t con_handle;

    bool accept_streaming_connection;
    bool outoing_signaling_active;
    bool decline_connection;

    avdtp_stream_endpoint_t * stream_endpoint = NULL;
    avdtp_connection_t * connection = NULL;

    switch (packet_type) {
        case L2CAP_DATA_PACKET:
            connection = avdtp_get_connection_for_l2cap_signaling_cid(channel);
            if (connection){
                handle_l2cap_data_packet_for_signaling_connection(connection, packet, size);
                break;
            }

            stream_endpoint = avdtp_get_stream_endpoint_for_l2cap_cid(channel);
            if (!stream_endpoint){
                if (!connection) break;
                handle_l2cap_data_packet_for_signaling_connection(connection, packet, size);
                break;
            }

            if (stream_endpoint->connection){
                if (channel == stream_endpoint->connection->l2cap_signaling_cid){
                    handle_l2cap_data_packet_for_signaling_connection(stream_endpoint->connection, packet, size);
                    break;
                }
            }

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

            if (channel == stream_endpoint->l2cap_reporting_cid){
                log_info("L2CAP_DATA_PACKET for reporting: NOT IMPLEMENTED");
            } else if (channel == stream_endpoint->l2cap_recovery_cid){
                log_info("L2CAP_DATA_PACKET for recovery: NOT IMPLEMENTED");
            } 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);
                    con_handle = l2cap_event_incoming_connection_get_handle(packet);
                    outoing_signaling_active = false;
                    accept_streaming_connection = false;

                    connection = avdtp_get_connection_for_bd_addr(event_addr);
                    if (connection != NULL){
                        switch (connection->state){
                            case AVDTP_SIGNALING_CONNECTION_W4_L2CAP_DISCONNECTED:
                            case AVDTP_SIGNALING_CONNECTION_W4_L2CAP_CONNECTED:
                                outoing_signaling_active = true;
                                connection->incoming_declined = true;
                                break;
                            case AVDTP_SIGNALING_CONNECTION_OPENED:
                                outoing_signaling_active = true;
                                accept_streaming_connection = true;
                                break;
                            default:
                                break;
                        }
                    }
                    log_info("incoming: %s, outoing_signaling_active %d, accept_streaming_connection %d",
                        bd_addr_to_str(event_addr), outoing_signaling_active, accept_streaming_connection);

                    decline_connection = outoing_signaling_active && !accept_streaming_connection;
                    if (outoing_signaling_active == false){
                        connection = avdtp_handle_incoming_connection(connection, event_addr, con_handle, local_cid);
                        if (connection == NULL){
                            decline_connection = true;
                        }
                    } else if (accept_streaming_connection){
                        if ((connection == NULL) || (connection->configuration_state != AVDTP_CONFIGURATION_STATE_REMOTE_CONFIGURED)) {
                            decline_connection = true;
                        } else {
                            // now, we're only dealing with media connections that are created by remote side - we're acceptor here
                            stream_endpoint = avdtp_get_stream_endpoint_for_seid(connection->acceptor_local_seid);
                            if ((stream_endpoint == NULL) || (stream_endpoint->l2cap_media_cid != 0) ) {
                                decline_connection = true;
                            }
                        }
                    }

                    if (decline_connection){
                        l2cap_decline_connection(local_cid);
                    } else {
                        l2cap_accept_connection(local_cid);
                    }
                    break;

                case L2CAP_EVENT_CHANNEL_OPENED:

                    psm = l2cap_event_channel_opened_get_psm(packet);
                    if (psm != BLUETOOTH_PSM_AVDTP){
                        log_info("Unexpected PSM - Not implemented yet, avdtp sink: L2CAP_EVENT_CHANNEL_OPENED ");
                        return;
                    }

                    status = l2cap_event_channel_opened_get_status(packet);
                    // inform about new l2cap connection
                    l2cap_event_channel_opened_get_address(packet, event_addr);
                    local_cid = l2cap_event_channel_opened_get_local_cid(packet);
                    l2cap_mtu = l2cap_event_channel_opened_get_remote_mtu(packet);
                    connection = avdtp_get_connection_for_bd_addr(event_addr);
                    if (connection == NULL){
                        log_info("L2CAP_EVENT_CHANNEL_OPENED: no connection found for %s", bd_addr_to_str(event_addr));
                        break;
                    }

                    con_handle = l2cap_event_channel_opened_get_handle(packet);

                    switch (connection->state){
                        case AVDTP_SIGNALING_CONNECTION_W4_L2CAP_CONNECTED:
                            switch (status){
                                case ERROR_CODE_SUCCESS:
                                    connection->l2cap_signaling_cid = local_cid;
                                    connection->incoming_declined = false;
                                    connection->l2cap_mtu = l2cap_mtu;
                                    connection->con_handle = con_handle;
                                    connection->state = AVDTP_SIGNALING_CONNECTION_OPENED;
                                    log_info("Connection opened l2cap_signaling_cid 0x%02x, avdtp_cid 0x%02x, con_handle 0x%02x", connection->l2cap_signaling_cid, connection->avdtp_cid, con_handle);
                                    avdtp_signaling_emit_connection_established(connection->avdtp_cid, event_addr, con_handle, status);
                                    return;
                                case L2CAP_CONNECTION_RESPONSE_RESULT_REFUSED_RESOURCES:
                                    if (connection->incoming_declined == true) {
                                        log_info("Connection was declined, and the outgoing failed");
                                        connection->state = AVDTP_SIGNALING_CONNECTION_W2_L2CAP_RETRY;
                                        connection->incoming_declined = false;
                                        avdtp_retry_timer_start(connection);
                                        return;
                                    }
                                    break;
                                default:
                                    log_info("Connection to %s failed. status code 0x%02x", bd_addr_to_str(event_addr), status);
                                    break;
                            }
                            avdtp_signaling_emit_connection_established(connection->avdtp_cid, event_addr, con_handle, status);
                            avdtp_finalize_connection(connection);
                            break;

                        case AVDTP_SIGNALING_CONNECTION_OPENED:
                            stream_endpoint = avdtp_get_stream_endpoint_for_signaling_cid(connection->l2cap_signaling_cid);
                            if (!stream_endpoint){
                                log_info("L2CAP_EVENT_CHANNEL_OPENED: stream_endpoint not found for signaling cid 0x%02x", connection->l2cap_signaling_cid);
                                return;
                            }
                            if (status != ERROR_CODE_SUCCESS){
                                log_info("AVDTP_STREAM_ENDPOINT_OPENED failed with status %d, avdtp cid 0x%02x, l2cap_media_cid 0x%02x, local seid %d, remote seid %d", status, connection->avdtp_cid, stream_endpoint->l2cap_media_cid, avdtp_local_seid(stream_endpoint), avdtp_remote_seid(stream_endpoint));
                                stream_endpoint->state = AVDTP_STREAM_ENDPOINT_IDLE;
                                avdtp_streaming_emit_connection_established(stream_endpoint, status);
                                break;
                            }
                            switch (stream_endpoint->state){
                                case AVDTP_STREAM_ENDPOINT_W4_L2CAP_FOR_MEDIA_CONNECTED:
                                    stream_endpoint->state = AVDTP_STREAM_ENDPOINT_OPENED;
                                    stream_endpoint->l2cap_media_cid = l2cap_event_channel_opened_get_local_cid(packet);
                                    stream_endpoint->media_con_handle = l2cap_event_channel_opened_get_handle(packet);

                                    log_info("AVDTP_STREAM_ENDPOINT_OPENED, avdtp cid 0x%02x, l2cap_media_cid 0x%02x, local seid %d, remote seid %d", connection->avdtp_cid, stream_endpoint->l2cap_media_cid, avdtp_local_seid(stream_endpoint), avdtp_remote_seid(stream_endpoint));
                                    avdtp_streaming_emit_connection_established(stream_endpoint, ERROR_CODE_SUCCESS);
                                    break;
                                default:
                                    log_info("AVDTP_STREAM_ENDPOINT_OPENED failed - stream endpoint in wrong state %d, avdtp cid 0x%02x, l2cap_media_cid 0x%02x, local seid %d, remote seid %d", stream_endpoint->state, connection->avdtp_cid, stream_endpoint->l2cap_media_cid, avdtp_local_seid(stream_endpoint), avdtp_remote_seid(stream_endpoint));
                                    avdtp_streaming_emit_connection_established(stream_endpoint, ERROR_CODE_COMMAND_DISALLOWED);
                                    break;
                            }
                            break;

                        default:
                            log_info("L2CAP connection to %s ignored: status code 0x%02x, connection state %d", bd_addr_to_str(event_addr), status, connection->state);
                            break;
                    }
                    break;

                case L2CAP_EVENT_CHANNEL_CLOSED:
                    local_cid = l2cap_event_channel_closed_get_local_cid(packet);
                    stream_endpoint = avdtp_get_stream_endpoint_for_l2cap_cid(local_cid);
                    connection = avdtp_get_connection_for_l2cap_signaling_cid(local_cid);

                    log_info("Received L2CAP_EVENT_CHANNEL_CLOSED, cid 0x%2x, connection %p, stream_endpoint %p", local_cid, connection, stream_endpoint);

                    if (stream_endpoint){
                        if (stream_endpoint->l2cap_media_cid == local_cid){
                            avdtp_handle_close_media_channel(stream_endpoint);
                            break;
                        }
                        if (stream_endpoint->l2cap_recovery_cid == local_cid){
                            avdtp_handle_close_recovery_channel(stream_endpoint);
                            break;
                        }
                        if (stream_endpoint->l2cap_reporting_cid == local_cid){
                            avdtp_handle_close_reporting_channel(stream_endpoint);
                            break;
                        }
                    }

                    if (connection){
                        // closing signaling channel invalidates all other channels as well
                        btstack_linked_list_iterator_t it;
                        btstack_linked_list_iterator_init(&it, avdtp_get_stream_endpoints());
                        while (btstack_linked_list_iterator_has_next(&it)){
                            stream_endpoint = (avdtp_stream_endpoint_t *)btstack_linked_list_iterator_next(&it);
                            if (stream_endpoint->connection == connection){
                                avdtp_handle_close_recovery_channel(stream_endpoint);
                                avdtp_handle_close_reporting_channel(stream_endpoint);
                                avdtp_handle_close_media_channel(stream_endpoint);
                                avdtp_reset_stream_endpoint(stream_endpoint);
                            }
                        }
                        avdtp_signaling_emit_connection_released(connection->avdtp_cid);
                        avdtp_finalize_connection(connection);
                        break;
                    }
                    break;

                case L2CAP_EVENT_CAN_SEND_NOW:
                    log_debug("avdtp_packet_handler, L2CAP_EVENT_CAN_SEND_NOW l2cap_cid 0x%02x", channel);
					avdtp_handle_can_send_now(channel);
                    break;
                default:
                    log_info("Unknown HCI event type %02x", hci_event_packet_get_type(packet));
                    break;
            }
            break;

        default:
            // other packet type
            break;
    }
}

uint8_t avdtp_disconnect(uint16_t avdtp_cid){
    avdtp_connection_t * connection = avdtp_get_connection_for_avdtp_cid(avdtp_cid);
    if (!connection) return ERROR_CODE_UNKNOWN_CONNECTION_IDENTIFIER;

    if (connection->state == AVDTP_SIGNALING_CONNECTION_W4_L2CAP_DISCONNECTED) return ERROR_CODE_SUCCESS;

    btstack_linked_list_iterator_t it;
    btstack_linked_list_iterator_init(&it, avdtp_get_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) continue;

        switch (stream_endpoint->state){
            case AVDTP_STREAM_ENDPOINT_OPENED:
            case AVDTP_STREAM_ENDPOINT_STREAMING:
                stream_endpoint->state = AVDTP_STREAM_ENDPOINT_W4_L2CAP_FOR_MEDIA_DISCONNECTED;
                l2cap_disconnect(stream_endpoint->l2cap_media_cid, 0);
                break;
            default:
                break;
        }
    }

    connection->state = AVDTP_SIGNALING_CONNECTION_W4_L2CAP_DISCONNECTED;
    l2cap_disconnect(connection->l2cap_signaling_cid, 0);
    return ERROR_CODE_SUCCESS;
}

uint8_t avdtp_open_stream(uint16_t avdtp_cid, uint8_t local_seid, uint8_t remote_seid){
    avdtp_connection_t * connection = avdtp_get_connection_for_avdtp_cid(avdtp_cid);
    if (!connection){
        log_error("avdtp_media_connect: no connection for signaling cid 0x%02x found", avdtp_cid);
        return ERROR_CODE_UNKNOWN_CONNECTION_IDENTIFIER;
    }

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

    avdtp_stream_endpoint_t * stream_endpoint = avdtp_get_stream_endpoint_for_seid(local_seid);
    if (!stream_endpoint) {
        log_error("avdtp_media_connect: no stream_endpoint with seid %d found", local_seid);
        return ERROR_CODE_UNKNOWN_CONNECTION_IDENTIFIER;
    }

    if (stream_endpoint->remote_sep.seid != remote_seid){
        log_error("avdtp_media_connect: no remote sep with seid %d registered with the stream endpoint", remote_seid);
        return ERROR_CODE_UNKNOWN_CONNECTION_IDENTIFIER;
    }

    if (stream_endpoint->state < AVDTP_STREAM_ENDPOINT_CONFIGURED) return ERROR_CODE_COMMAND_DISALLOWED;

    connection->initiator_transaction_label= avdtp_get_next_transaction_label();
    connection->initiator_remote_seid = remote_seid;
    connection->initiator_local_seid = local_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);
    return ERROR_CODE_SUCCESS;
}

uint8_t avdtp_start_stream(uint16_t avdtp_cid, uint8_t local_seid){
    avdtp_connection_t * connection = avdtp_get_connection_for_avdtp_cid(avdtp_cid);
    if (!connection){
        log_error("avdtp_start_stream: no connection for signaling cid 0x%02x found", avdtp_cid);
        return ERROR_CODE_UNKNOWN_CONNECTION_IDENTIFIER;
    }

    avdtp_stream_endpoint_t * stream_endpoint = avdtp_get_stream_endpoint_for_seid(local_seid);
    if (!stream_endpoint) {
        log_error("avdtp_start_stream: no stream_endpoint with seid %d found", local_seid);
        return ERROR_CODE_UNKNOWN_CONNECTION_IDENTIFIER;
    }

    if (stream_endpoint->l2cap_media_cid == 0){
        log_error("avdtp_start_stream: no media connection for stream_endpoint with seid %d found", local_seid);
        return ERROR_CODE_UNKNOWN_CONNECTION_IDENTIFIER;
    }

    if (!is_avdtp_remote_seid_registered(stream_endpoint)){
        log_error("avdtp_media_connect: no remote sep registered with the stream endpoint");
        return ERROR_CODE_UNKNOWN_CONNECTION_IDENTIFIER;
    }

    if (!is_avdtp_remote_seid_registered(stream_endpoint) || stream_endpoint->start_stream == 1){
        return ERROR_CODE_COMMAND_DISALLOWED;
    }

    if (stream_endpoint->start_stream == 1) {
        return ERROR_CODE_COMMAND_DISALLOWED;
    }

    stream_endpoint->start_stream = 1;
    connection->initiator_local_seid = local_seid;
    connection->initiator_remote_seid = stream_endpoint->remote_sep.seid;
	avdtp_request_can_send_now_initiator(connection);
    return ERROR_CODE_SUCCESS;
}

uint8_t avdtp_stop_stream(uint16_t avdtp_cid, uint8_t local_seid){
    avdtp_connection_t * connection = avdtp_get_connection_for_avdtp_cid(avdtp_cid);
    if (!connection){
        log_error("avdtp_stop_stream: no connection for signaling cid 0x%02x found", avdtp_cid);
        return ERROR_CODE_UNKNOWN_CONNECTION_IDENTIFIER;
    }

    avdtp_stream_endpoint_t * stream_endpoint = avdtp_get_stream_endpoint_for_seid(local_seid);
    if (!stream_endpoint) {
        log_error("avdtp_stop_stream: no stream_endpoint with seid %d found", local_seid);
        return ERROR_CODE_UNKNOWN_CONNECTION_IDENTIFIER;
    }

    if (stream_endpoint->l2cap_media_cid == 0){
        log_error("avdtp_stop_stream: no media connection for stream_endpoint with seid %d found", local_seid);
        return ERROR_CODE_UNKNOWN_CONNECTION_IDENTIFIER;
    }

    if (!is_avdtp_remote_seid_registered(stream_endpoint) || stream_endpoint->close_stream){
        return ERROR_CODE_COMMAND_DISALLOWED;
    }

    if (stream_endpoint->close_stream == 1) {
        return ERROR_CODE_COMMAND_DISALLOWED;
    }

    stream_endpoint->close_stream = 1;
    connection->initiator_local_seid = local_seid;
    connection->initiator_remote_seid = stream_endpoint->remote_sep.seid;
	avdtp_request_can_send_now_initiator(connection);
    return ERROR_CODE_SUCCESS;
}

uint8_t avdtp_abort_stream(uint16_t avdtp_cid, uint8_t local_seid){
    avdtp_connection_t * connection = avdtp_get_connection_for_avdtp_cid(avdtp_cid);
    if (!connection){
        log_error("avdtp_abort_stream: no connection for signaling cid 0x%02x found", avdtp_cid);
        return ERROR_CODE_UNKNOWN_CONNECTION_IDENTIFIER;
    }

    avdtp_stream_endpoint_t * stream_endpoint = avdtp_get_stream_endpoint_for_seid(local_seid);
    if (!stream_endpoint) {
        log_error("avdtp_abort_stream: no stream_endpoint with seid %d found", local_seid);
        return ERROR_CODE_UNKNOWN_CONNECTION_IDENTIFIER;
    }

    if (stream_endpoint->l2cap_media_cid == 0){
        log_error("avdtp_abort_stream: no media connection for stream_endpoint with seid %d found", local_seid);
        return ERROR_CODE_UNKNOWN_CONNECTION_IDENTIFIER;
    }

    if (!is_avdtp_remote_seid_registered(stream_endpoint) || stream_endpoint->abort_stream){
        return ERROR_CODE_COMMAND_DISALLOWED;
    }

    if (stream_endpoint->abort_stream == 1) {
        return ERROR_CODE_COMMAND_DISALLOWED;
    }

    stream_endpoint->abort_stream = 1;
    connection->initiator_local_seid = local_seid;
    connection->initiator_remote_seid = stream_endpoint->remote_sep.seid;
	avdtp_request_can_send_now_initiator(connection);
    return ERROR_CODE_SUCCESS;
}

uint8_t avdtp_suspend_stream(uint16_t avdtp_cid, uint8_t local_seid){
    avdtp_connection_t * connection = avdtp_get_connection_for_avdtp_cid(avdtp_cid);
    if (!connection){
        log_error("avdtp_suspend_stream: no connection for signaling cid 0x%02x found", avdtp_cid);
        return ERROR_CODE_UNKNOWN_CONNECTION_IDENTIFIER;
    }
    avdtp_stream_endpoint_t * stream_endpoint = avdtp_get_stream_endpoint_for_seid(local_seid);
    if (!stream_endpoint) {
        log_error("avdtp_suspend_stream: no stream_endpoint with seid %d found", local_seid);
        return ERROR_CODE_UNKNOWN_CONNECTION_IDENTIFIER;
    }

    if (stream_endpoint->l2cap_media_cid == 0){
        log_error("avdtp_suspend_stream: no media connection for stream_endpoint with seid %d found", local_seid);
        return ERROR_CODE_UNKNOWN_CONNECTION_IDENTIFIER;
    }

    if (!is_avdtp_remote_seid_registered(stream_endpoint) || stream_endpoint->suspend_stream){
        return ERROR_CODE_COMMAND_DISALLOWED;
    }

    if (stream_endpoint->suspend_stream == 1) {
        return ERROR_CODE_COMMAND_DISALLOWED;
    }

    stream_endpoint->suspend_stream = 1;
    connection->initiator_local_seid = local_seid;
    connection->initiator_remote_seid = stream_endpoint->remote_sep.seid;
	avdtp_request_can_send_now_initiator(connection);
    return ERROR_CODE_SUCCESS;
}

uint8_t avdtp_discover_stream_endpoints(uint16_t avdtp_cid){
    avdtp_connection_t * connection = avdtp_get_connection_for_avdtp_cid(avdtp_cid);
    if (!connection){
        log_error("avdtp_discover_stream_endpoints: no connection for signaling cid 0x%02x found", avdtp_cid);
        return ERROR_CODE_UNKNOWN_CONNECTION_IDENTIFIER;
    }
    if ((connection->state != AVDTP_SIGNALING_CONNECTION_OPENED) ||
        (connection->initiator_connection_state != AVDTP_SIGNALING_CONNECTION_INITIATOR_IDLE)) {
        return ERROR_CODE_COMMAND_DISALLOWED;
    }

    connection->initiator_transaction_label= avdtp_get_next_transaction_label();
    connection->initiator_connection_state = AVDTP_SIGNALING_CONNECTION_INITIATOR_W2_DISCOVER_SEPS;
    return avdtp_request_can_send_now_initiator(connection);
}


uint8_t avdtp_get_capabilities(uint16_t avdtp_cid, uint8_t remote_seid){
    avdtp_connection_t * connection = avdtp_get_connection_for_avdtp_cid(avdtp_cid);
    if (!connection){
        log_error("No connection for AVDTP cid 0x%02x found", avdtp_cid);
        return ERROR_CODE_UNKNOWN_CONNECTION_IDENTIFIER;
    }
    if ((connection->state != AVDTP_SIGNALING_CONNECTION_OPENED) ||
        (connection->initiator_connection_state != AVDTP_SIGNALING_CONNECTION_INITIATOR_IDLE)) {
        return ERROR_CODE_COMMAND_DISALLOWED;
    }

    connection->initiator_transaction_label= avdtp_get_next_transaction_label();
    connection->initiator_connection_state = AVDTP_SIGNALING_CONNECTION_INITIATOR_W2_GET_CAPABILITIES;
    connection->initiator_remote_seid = remote_seid;
    return avdtp_request_can_send_now_initiator(connection);
}


uint8_t avdtp_get_all_capabilities(uint16_t avdtp_cid, uint8_t remote_seid){
    avdtp_connection_t * connection = avdtp_get_connection_for_avdtp_cid(avdtp_cid);
    if (!connection){
        log_error("No connection for AVDTP cid 0x%02x found", avdtp_cid);
        return ERROR_CODE_UNKNOWN_CONNECTION_IDENTIFIER;
    }
    if ((connection->state != AVDTP_SIGNALING_CONNECTION_OPENED) ||
        (connection->initiator_connection_state != AVDTP_SIGNALING_CONNECTION_INITIATOR_IDLE)) {
        return ERROR_CODE_COMMAND_DISALLOWED;
    }

    connection->initiator_transaction_label= avdtp_get_next_transaction_label();
    connection->initiator_remote_seid = remote_seid;

    if (connection->avdtp_version == 0){
        connection->initiator_connection_state = AVDTP_SIGNALING_CONNECTION_INITIATOR_W2_SEND_SDP_QUERY_THEN_GET_ALL_CAPABILITIES;
        avdtp_handle_sdp_client_query_request.callback = &avdtp_handle_start_sdp_client_query;
        // ignore ERROR_CODE_COMMAND_DISALLOWED because in that case, we already have requested an SDP callback
        (void) sdp_client_register_query_callback(&avdtp_handle_sdp_client_query_request);
        return ERROR_CODE_SUCCESS;
    } else {
        // AVDTP version lower then 1.3 supports only get capabilities command
        if (connection->avdtp_version < 0x103){
            connection->initiator_connection_state = AVDTP_SIGNALING_CONNECTION_INITIATOR_W2_GET_CAPABILITIES;
        } else {
            connection->initiator_connection_state = AVDTP_SIGNALING_CONNECTION_INITIATOR_W2_GET_ALL_CAPABILITIES;
        }
        return avdtp_request_can_send_now_initiator(connection);
    }
}

uint8_t avdtp_get_configuration(uint16_t avdtp_cid, uint8_t remote_seid){
    avdtp_connection_t * connection = avdtp_get_connection_for_avdtp_cid(avdtp_cid);
    if (!connection){
        log_error("No connection for AVDTP cid 0x%02x found", avdtp_cid);
        return ERROR_CODE_UNKNOWN_CONNECTION_IDENTIFIER;
    }
    if ((connection->state != AVDTP_SIGNALING_CONNECTION_OPENED) ||
        (connection->initiator_connection_state != AVDTP_SIGNALING_CONNECTION_INITIATOR_IDLE)) {
        return ERROR_CODE_COMMAND_DISALLOWED;
    }

    connection->initiator_transaction_label= avdtp_get_next_transaction_label();
    connection->initiator_connection_state = AVDTP_SIGNALING_CONNECTION_INITIATOR_W2_GET_CONFIGURATION;
    connection->initiator_remote_seid = remote_seid;
    return avdtp_request_can_send_now_initiator(connection);
}

uint8_t avdtp_set_configuration(uint16_t avdtp_cid, uint8_t local_seid, uint8_t remote_seid, uint16_t configured_services_bitmap, avdtp_capabilities_t configuration){
    avdtp_connection_t * connection = avdtp_get_connection_for_avdtp_cid(avdtp_cid);
    if (!connection){
        log_error("No connection for AVDTP cid 0x%02x found", avdtp_cid);
        return ERROR_CODE_UNKNOWN_CONNECTION_IDENTIFIER;
    }
    if ((connection->state != AVDTP_SIGNALING_CONNECTION_OPENED) ||
        (connection->initiator_connection_state != AVDTP_SIGNALING_CONNECTION_INITIATOR_IDLE)) {
        log_error("connection in wrong state, %d, initiator state %d", connection->state, connection->initiator_connection_state);
        return ERROR_CODE_COMMAND_DISALLOWED;
    }
    if (connection->configuration_state != AVDTP_CONFIGURATION_STATE_IDLE){
        log_info("configuration already started, config state %u", connection->configuration_state);
        return ERROR_CODE_COMMAND_DISALLOWED;
    }

    avdtp_stream_endpoint_t * stream_endpoint = avdtp_get_stream_endpoint_for_seid(local_seid);
    if (!stream_endpoint) {
        log_error("No initiator stream endpoint for seid %d", local_seid);
        return ERROR_CODE_UNKNOWN_CONNECTION_IDENTIFIER;
    }
    if (stream_endpoint->state >= AVDTP_STREAM_ENDPOINT_CONFIGURED){
        log_error("Stream endpoint seid %d in wrong state %d", local_seid, stream_endpoint->state);
        return ERROR_CODE_COMMAND_DISALLOWED;
    }

    connection->active_stream_endpoint = (void*) stream_endpoint;
    connection->configuration_state = AVDTP_CONFIGURATION_STATE_LOCAL_INITIATED;

    connection->initiator_transaction_label= avdtp_get_next_transaction_label();
    connection->initiator_remote_seid = remote_seid;
    connection->initiator_local_seid = local_seid;
    stream_endpoint->remote_configuration_bitmap = configured_services_bitmap;
    stream_endpoint->remote_configuration = configuration;
    stream_endpoint->initiator_config_state = AVDTP_INITIATOR_W2_SET_CONFIGURATION;

	log_debug("SE %p, initiator_config_state: 0x%02x", stream_endpoint, stream_endpoint->initiator_config_state);

    return avdtp_request_can_send_now_initiator(connection);
}

uint8_t avdtp_reconfigure(uint16_t avdtp_cid, uint8_t local_seid, uint8_t remote_seid, uint16_t configured_services_bitmap, avdtp_capabilities_t configuration){
    avdtp_connection_t * connection = avdtp_get_connection_for_avdtp_cid(avdtp_cid);
    if (!connection){
        log_error("No connection for AVDTP cid 0x%02x found", avdtp_cid);
        return ERROR_CODE_UNKNOWN_CONNECTION_IDENTIFIER;
    }
    //TODO: if opened only app capabilities, enable reconfigure for not opened
    if ((connection->state != AVDTP_SIGNALING_CONNECTION_OPENED) ||
        (connection->initiator_connection_state != AVDTP_SIGNALING_CONNECTION_INITIATOR_IDLE)) {
        return ERROR_CODE_COMMAND_DISALLOWED;
    }

    avdtp_stream_endpoint_t * stream_endpoint = avdtp_get_stream_endpoint_for_seid(local_seid);
    if (!stream_endpoint) {
        log_error("avdtp_reconfigure: no initiator stream endpoint for seid %d", local_seid);
        return ERROR_CODE_UNKNOWN_CONNECTION_IDENTIFIER;
    }

    if (!is_avdtp_remote_seid_registered(stream_endpoint)){
        log_error("avdtp_reconfigure: no associated remote sep");
        return ERROR_CODE_COMMAND_DISALLOWED;
    }

    connection->initiator_transaction_label= avdtp_get_next_transaction_label();
    connection->initiator_remote_seid = remote_seid;
    connection->initiator_local_seid = local_seid;
    stream_endpoint->remote_configuration_bitmap = configured_services_bitmap;
    stream_endpoint->remote_configuration = configuration;
    stream_endpoint->initiator_config_state = AVDTP_INITIATOR_W2_RECONFIGURE_STREAM_WITH_SEID;
    return avdtp_request_can_send_now_initiator(connection);
}

void    avdtp_set_preferred_sampling_frequency(avdtp_stream_endpoint_t * stream_endpoint, uint32_t sampling_frequency){
    stream_endpoint->preferred_sampling_frequency = sampling_frequency;
}

void    avdtp_set_preferred_channel_mode(avdtp_stream_endpoint_t * stream_endpoint, uint8_t channel_mode){
    stream_endpoint->preferred_channel_mode = channel_mode;
}


avdtp_channel_mode_t avdtp_choose_sbc_channel_mode(avdtp_stream_endpoint_t * stream_endpoint, uint8_t remote_channel_mode_bitmap){
    uint8_t * media_codec = stream_endpoint->sep.capabilities.media_codec.media_codec_information;
    uint8_t channel_mode_bitmap = (media_codec[0] & 0x0F) & remote_channel_mode_bitmap;

    // use preferred channel mode if possible
    if (stream_endpoint->preferred_channel_mode == AVDTP_SBC_JOINT_STEREO){
        return AVDTP_CHANNEL_MODE_JOINT_STEREO;
    }
    if (stream_endpoint->preferred_channel_mode == AVDTP_SBC_STEREO){
        return AVDTP_CHANNEL_MODE_STEREO;
    }
    if (stream_endpoint->preferred_channel_mode == AVDTP_SBC_DUAL_CHANNEL){
        return AVDTP_CHANNEL_MODE_DUAL_CHANNEL;
    }
    if (stream_endpoint->preferred_channel_mode == AVDTP_SBC_MONO){
        return AVDTP_CHANNEL_MODE_MONO;
    }


    if (channel_mode_bitmap & AVDTP_SBC_JOINT_STEREO){
        return AVDTP_CHANNEL_MODE_JOINT_STEREO;
    } else if (channel_mode_bitmap & AVDTP_SBC_STEREO){
        return AVDTP_CHANNEL_MODE_STEREO;
    } else if (channel_mode_bitmap & AVDTP_SBC_DUAL_CHANNEL){
        return AVDTP_CHANNEL_MODE_DUAL_CHANNEL;
    } else if (channel_mode_bitmap & AVDTP_SBC_MONO){
        return AVDTP_CHANNEL_MODE_MONO;
    }
    return AVDTP_CHANNEL_MODE_JOINT_STEREO;
}

avdtp_sbc_allocation_method_t avdtp_choose_sbc_allocation_method(avdtp_stream_endpoint_t * stream_endpoint, uint8_t remote_allocation_method_bitmap){
    uint8_t * media_codec = stream_endpoint->sep.capabilities.media_codec.media_codec_information;
    uint8_t allocation_method_bitmap = (media_codec[1] & 0x03) & remote_allocation_method_bitmap;

    avdtp_sbc_allocation_method_t allocation_method = AVDTP_SBC_ALLOCATION_METHOD_LOUDNESS;
    if (allocation_method_bitmap & AVDTP_SBC_ALLOCATION_METHOD_LOUDNESS){
        allocation_method = AVDTP_SBC_ALLOCATION_METHOD_LOUDNESS;
    } else if (allocation_method_bitmap & AVDTP_SBC_ALLOCATION_METHOD_SNR){
        allocation_method = AVDTP_SBC_ALLOCATION_METHOD_SNR;
    }
    return allocation_method;
}

uint8_t avdtp_stream_endpoint_seid(avdtp_stream_endpoint_t * stream_endpoint){
    if (!stream_endpoint) return 0;
    return stream_endpoint->sep.seid;
}
uint8_t avdtp_choose_sbc_subbands(avdtp_stream_endpoint_t * stream_endpoint, uint8_t remote_subbands_bitmap){
    if (!stream_endpoint) return 0;
    uint8_t * media_codec = stream_endpoint->sep.capabilities.media_codec.media_codec_information;
    uint8_t subbands_bitmap = ((media_codec[1] >> 2) & 0x03) & remote_subbands_bitmap;

    uint8_t subbands = AVDTP_SBC_SUBBANDS_8;
    if (subbands_bitmap & AVDTP_SBC_SUBBANDS_8){
        subbands = AVDTP_SBC_SUBBANDS_8;
    } else if (subbands_bitmap & AVDTP_SBC_SUBBANDS_4){
        subbands = AVDTP_SBC_SUBBANDS_4;
    }
    return subbands;
}

uint8_t avdtp_choose_sbc_block_length(avdtp_stream_endpoint_t * stream_endpoint, uint8_t remote_block_length_bitmap){
    if (!stream_endpoint) return 0;
    uint8_t * media_codec = stream_endpoint->sep.capabilities.media_codec.media_codec_information;
    uint8_t block_length_bitmap = (media_codec[1] >> 4) & remote_block_length_bitmap;

    uint8_t block_length = AVDTP_SBC_BLOCK_LENGTH_16;
    if (block_length_bitmap & AVDTP_SBC_BLOCK_LENGTH_16){
        block_length = AVDTP_SBC_BLOCK_LENGTH_16;
    } else if (block_length_bitmap & AVDTP_SBC_BLOCK_LENGTH_12){
        block_length = AVDTP_SBC_BLOCK_LENGTH_12;
    } else if (block_length_bitmap & AVDTP_SBC_BLOCK_LENGTH_8){
        block_length = AVDTP_SBC_BLOCK_LENGTH_8;
    } else if (block_length_bitmap & AVDTP_SBC_BLOCK_LENGTH_4){
        block_length = AVDTP_SBC_BLOCK_LENGTH_4;
    }
    return block_length;
}

uint16_t avdtp_choose_sbc_sampling_frequency(avdtp_stream_endpoint_t * stream_endpoint, uint8_t remote_sampling_frequency_bitmap){
    if (!stream_endpoint) return 0;
    uint8_t * media_codec = stream_endpoint->sep.capabilities.media_codec.media_codec_information;
    uint8_t supported_sampling_frequency_bitmap = (media_codec[0] >> 4) & remote_sampling_frequency_bitmap;

    // use preferred sampling frequency if possible
    if ((stream_endpoint->preferred_sampling_frequency == 48000) && (supported_sampling_frequency_bitmap & AVDTP_SBC_48000)){
        return stream_endpoint->preferred_sampling_frequency;
    }
    if ((stream_endpoint->preferred_sampling_frequency == 44100) && (supported_sampling_frequency_bitmap & AVDTP_SBC_44100)){
        return stream_endpoint->preferred_sampling_frequency;
    }
    if ((stream_endpoint->preferred_sampling_frequency == 32000) && (supported_sampling_frequency_bitmap & AVDTP_SBC_32000)){
        return stream_endpoint->preferred_sampling_frequency;
    }
    if ((stream_endpoint->preferred_sampling_frequency == 16000) && (supported_sampling_frequency_bitmap & AVDTP_SBC_16000)){
        return stream_endpoint->preferred_sampling_frequency;
    }

    // otherwise, use highest available
    if (supported_sampling_frequency_bitmap & AVDTP_SBC_48000){
        return 48000;
    }
    if (supported_sampling_frequency_bitmap & AVDTP_SBC_44100){
        return 44100;
    }
    if (supported_sampling_frequency_bitmap & AVDTP_SBC_32000){
        return 32000;
    }
    if (supported_sampling_frequency_bitmap & AVDTP_SBC_16000){
        return 16000;
    }
    return 44100; // some default
}

uint8_t avdtp_choose_sbc_max_bitpool_value(avdtp_stream_endpoint_t * stream_endpoint, uint8_t remote_max_bitpool_value){
    if (!stream_endpoint) return 0;
    uint8_t * media_codec = stream_endpoint->sep.capabilities.media_codec.media_codec_information;
    return btstack_min(media_codec[3], remote_max_bitpool_value);
}

uint8_t avdtp_choose_sbc_min_bitpool_value(avdtp_stream_endpoint_t * stream_endpoint, uint8_t remote_min_bitpool_value){
    if (!stream_endpoint) return 0;
    uint8_t * media_codec = stream_endpoint->sep.capabilities.media_codec.media_codec_information;
    return btstack_max(media_codec[2], remote_min_bitpool_value);
}

uint8_t is_avdtp_remote_seid_registered(avdtp_stream_endpoint_t * stream_endpoint){
    if (!stream_endpoint) return 0;
    if (stream_endpoint->remote_sep.seid == 0) return 0;
    if (stream_endpoint->remote_sep.seid > 0x3E) return 0;
    return 1;
}

void avdtp_init(void){
    if (!l2cap_registered){
        l2cap_registered = true;
        l2cap_register_service(&avdtp_packet_handler, BLUETOOTH_PSM_AVDTP, 0xffff, gap_get_security_level());
    }
}

void avdtp_deinit(void){
    l2cap_registered = false;
    stream_endpoints = NULL;
    connections = NULL;
    avdtp_sink_handle_media_data = NULL;
    avdtp_media_config_validator = NULL;

    sdp_query_context_avdtp_cid = 0;
    stream_endpoints_id_counter = 0;
    transaction_id_counter = 0;
    avdtp_cid_counter = 0;
}