xref: /external/bluetooth/bluedroid/stack/avdt/avdt_msg.c

/******************************************************************************
 *
 *  Copyright (C) 2002-2012 Broadcom Corporation
 *
 *  Licensed under the Apache License, Version 2.0 (the "License");
 *  you may not use this file except in compliance with the License.
 *  You may obtain a copy of the License at:
 *
 *  http://www.apache.org/licenses/LICENSE-2.0
 *
 *  Unless required by applicable law or agreed to in writing, software
 *  distributed under the License is distributed on an "AS IS" BASIS,
 *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 *  See the License for the specific language governing permissions and
 *  limitations under the License.
 *
 ******************************************************************************/

/******************************************************************************
 *
 *  This module contains functions for parsing and building AVDTP signaling
 *  messages.  It also contains functions called by the SCB or CCB state
 *  machines for sending command, response, and reject messages.  It also
 *  contains a function that processes incoming messages and dispatches them
 *  to the appropriate SCB or CCB.
 *
 ******************************************************************************/

#include <string.h>
#include "data_types.h"
#include "bt_target.h"
#include "avdt_api.h"
#include "avdtc_api.h"
#include "avdt_int.h"
#include "gki.h"
#include "btu.h"

/*****************************************************************************
** constants
*****************************************************************************/

/* mask of all psc values */
#define AVDT_MSG_PSC_MASK   (AVDT_PSC_TRANS | AVDT_PSC_REPORT | AVDT_PSC_DELAY_RPT | \
                             AVDT_PSC_RECOV | AVDT_PSC_HDRCMP | AVDT_PSC_MUX)
#define AVDT_PSC_PROTECT    (1<<4)  /* Content Protection */
#define AVDT_PSC_CODEC      (1<<7)  /* codec */


/*****************************************************************************
** type definitions
*****************************************************************************/

/* type for message building functions */
typedef void (*tAVDT_MSG_BLD)(UINT8 **p, tAVDT_MSG *p_msg);

/* type for message parsing functions */
typedef UINT8 (*tAVDT_MSG_PRS)(tAVDT_MSG *p_msg, UINT8 *p, UINT16 len);


/*****************************************************************************
** local function declarations
*****************************************************************************/

static void avdt_msg_bld_none(UINT8 **p, tAVDT_MSG *p_msg);
static void avdt_msg_bld_single(UINT8 **p, tAVDT_MSG *p_msg);
static void avdt_msg_bld_setconfig_cmd(UINT8 **p, tAVDT_MSG *p_msg);
static void avdt_msg_bld_reconfig_cmd(UINT8 **p, tAVDT_MSG *p_msg);
static void avdt_msg_bld_multi(UINT8 **p, tAVDT_MSG *p_msg);
static void avdt_msg_bld_security_cmd(UINT8 **p, tAVDT_MSG *p_msg);
static void avdt_msg_bld_discover_rsp(UINT8 **p, tAVDT_MSG *p_msg);
static void avdt_msg_bld_svccap(UINT8 **p, tAVDT_MSG *p_msg);
static void avdt_msg_bld_security_rsp(UINT8 **p, tAVDT_MSG *p_msg);
static void avdt_msg_bld_all_svccap(UINT8 **p, tAVDT_MSG *p_msg);
static void avdt_msg_bld_delay_rpt(UINT8 **p, tAVDT_MSG *p_msg);

static UINT8 avdt_msg_prs_none(tAVDT_MSG *p_msg, UINT8 *p, UINT16 len);
static UINT8 avdt_msg_prs_single(tAVDT_MSG *p_msg, UINT8 *p, UINT16 len);
static UINT8 avdt_msg_prs_setconfig_cmd(tAVDT_MSG *p_msg, UINT8 *p, UINT16 len);
static UINT8 avdt_msg_prs_reconfig_cmd(tAVDT_MSG *p_msg, UINT8 *p, UINT16 len);
static UINT8 avdt_msg_prs_multi(tAVDT_MSG *p_msg, UINT8 *p, UINT16 len);
static UINT8 avdt_msg_prs_security_cmd(tAVDT_MSG *p_msg, UINT8 *p, UINT16 len);
static UINT8 avdt_msg_prs_discover_rsp(tAVDT_MSG *p_msg, UINT8 *p, UINT16 len);
static UINT8 avdt_msg_prs_svccap(tAVDT_MSG *p_msg, UINT8 *p, UINT16 len);
static UINT8 avdt_msg_prs_all_svccap(tAVDT_MSG *p_msg, UINT8 *p, UINT16 len);
static UINT8 avdt_msg_prs_security_rsp(tAVDT_MSG *p_msg, UINT8 *p, UINT16 len);
static UINT8 avdt_msg_prs_delay_rpt (tAVDT_MSG *p_msg, UINT8 *p, UINT16 len);

/*****************************************************************************
** constants
*****************************************************************************/

/* table of information element minimum lengths used for parsing */
const UINT8 avdt_msg_ie_len_min[] = {
    0,                              /* unused */
    AVDT_LEN_TRANS_MIN,             /* media transport */
    AVDT_LEN_REPORT_MIN,            /* reporting */
    AVDT_LEN_RECOV_MIN,             /* recovery */
    AVDT_LEN_PROTECT_MIN,           /* content protection */
    AVDT_LEN_HDRCMP_MIN,            /* header compression */
    AVDT_LEN_MUX_MIN,               /* multiplexing */
    AVDT_LEN_CODEC_MIN,             /* codec */
    AVDT_LEN_DELAY_RPT_MIN          /* delay report */
};

/* table of information element minimum lengths used for parsing */
const UINT8 avdt_msg_ie_len_max[] = {
    0,                              /* unused */
    AVDT_LEN_TRANS_MAX,             /* media transport */
    AVDT_LEN_REPORT_MAX,            /* reporting */
    AVDT_LEN_RECOV_MAX,             /* recovery */
    AVDT_LEN_PROTECT_MAX,           /* content protection */
    AVDT_LEN_HDRCMP_MAX,            /* header compression */
    AVDT_LEN_MUX_MAX,               /* multiplexing */
    AVDT_LEN_CODEC_MAX,             /* codec */
    AVDT_LEN_DELAY_RPT_MAX          /* delay report */
};

/* table of error codes used when decoding information elements */
const UINT8 avdt_msg_ie_err[] = {
    0,                              /* unused */
    AVDT_ERR_MEDIA_TRANS,           /* media transport */
    AVDT_ERR_LENGTH,                /* reporting */
    AVDT_ERR_RECOV_FMT,             /* recovery */
    AVDT_ERR_CP_FMT,                /* content protection */
    AVDT_ERR_ROHC_FMT,              /* header compression */
    AVDT_ERR_MUX_FMT,               /* multiplexing */
    AVDT_ERR_SERVICE,               /* codec */
    AVDT_ERR_SERVICE                /* delay report ?? */
};

/* table of packet type minimum lengths */
static const UINT8 avdt_msg_pkt_type_len[] = {
    AVDT_LEN_TYPE_SINGLE,
    AVDT_LEN_TYPE_START,
    AVDT_LEN_TYPE_CONT,
    AVDT_LEN_TYPE_END
};

/* function table for building command messages */
const tAVDT_MSG_BLD avdt_msg_bld_cmd[] = {
    avdt_msg_bld_none,            /* discover */
    avdt_msg_bld_single,          /* get capabilities */
    avdt_msg_bld_setconfig_cmd,   /* set configuration */
    avdt_msg_bld_single,          /* get configuration */
    avdt_msg_bld_reconfig_cmd,    /* reconfigure */
    avdt_msg_bld_single,          /* open */
    avdt_msg_bld_multi,           /* start */
    avdt_msg_bld_single,          /* close */
    avdt_msg_bld_multi,           /* suspend */
    avdt_msg_bld_single,          /* abort */
    avdt_msg_bld_security_cmd,    /* security control */
    avdt_msg_bld_single,          /* get all capabilities */
    avdt_msg_bld_delay_rpt        /* delay report */
};

/* function table for building response messages */
const tAVDT_MSG_BLD avdt_msg_bld_rsp[] = {
    avdt_msg_bld_discover_rsp,    /* discover */
    avdt_msg_bld_svccap,          /* get capabilities */
    avdt_msg_bld_none,            /* set configuration */
    avdt_msg_bld_all_svccap,      /* get configuration */
    avdt_msg_bld_none,            /* reconfigure */
    avdt_msg_bld_none,            /* open */
    avdt_msg_bld_none,            /* start */
    avdt_msg_bld_none,            /* close */
    avdt_msg_bld_none,            /* suspend */
    avdt_msg_bld_none,            /* abort */
    avdt_msg_bld_security_rsp,    /* security control */
    avdt_msg_bld_all_svccap,      /* get all capabilities */
    avdt_msg_bld_none             /* delay report */
};

/* function table for parsing command messages */
const tAVDT_MSG_PRS avdt_msg_prs_cmd[] = {
    avdt_msg_prs_none,            /* discover */
    avdt_msg_prs_single,          /* get capabilities */
    avdt_msg_prs_setconfig_cmd,   /* set configuration */
    avdt_msg_prs_single,          /* get configuration */
    avdt_msg_prs_reconfig_cmd,    /* reconfigure */
    avdt_msg_prs_single,          /* open */
    avdt_msg_prs_multi,           /* start */
    avdt_msg_prs_single,          /* close */
    avdt_msg_prs_multi,           /* suspend */
    avdt_msg_prs_single,          /* abort */
    avdt_msg_prs_security_cmd,    /* security control */
    avdt_msg_prs_single,          /* get all capabilities */
    avdt_msg_prs_delay_rpt        /* delay report */
};

/* function table for parsing response messages */
const tAVDT_MSG_PRS avdt_msg_prs_rsp[] = {
    avdt_msg_prs_discover_rsp,    /* discover */
    avdt_msg_prs_svccap,          /* get capabilities */
    avdt_msg_prs_none,            /* set configuration */
    avdt_msg_prs_all_svccap,      /* get configuration */
    avdt_msg_prs_none,            /* reconfigure */
    avdt_msg_prs_none,            /* open */
    avdt_msg_prs_none,            /* start */
    avdt_msg_prs_none,            /* close */
    avdt_msg_prs_none,            /* suspend */
    avdt_msg_prs_none,            /* abort */
    avdt_msg_prs_security_rsp,    /* security control */
    avdt_msg_prs_all_svccap,      /* get all capabilities */
    avdt_msg_prs_none             /* delay report */
};

/* command message-to-event lookup table */
const UINT8 avdt_msg_cmd_2_evt[] = {
    AVDT_CCB_MSG_DISCOVER_CMD_EVT + AVDT_CCB_MKR,   /* discover */
    AVDT_CCB_MSG_GETCAP_CMD_EVT + AVDT_CCB_MKR,     /* get capabilities */
    AVDT_SCB_MSG_SETCONFIG_CMD_EVT,                 /* set configuration */
    AVDT_SCB_MSG_GETCONFIG_CMD_EVT,                 /* get configuration */
    AVDT_SCB_MSG_RECONFIG_CMD_EVT,                  /* reconfigure */
    AVDT_SCB_MSG_OPEN_CMD_EVT,                      /* open */
    AVDT_CCB_MSG_START_CMD_EVT + AVDT_CCB_MKR,      /* start */
    AVDT_SCB_MSG_CLOSE_CMD_EVT,                     /* close */
    AVDT_CCB_MSG_SUSPEND_CMD_EVT + AVDT_CCB_MKR,    /* suspend */
    AVDT_SCB_MSG_ABORT_CMD_EVT,                     /* abort */
    AVDT_SCB_MSG_SECURITY_CMD_EVT,                  /* security control */
    AVDT_CCB_MSG_GETCAP_CMD_EVT + AVDT_CCB_MKR,     /* get all capabilities */
    AVDT_SCB_MSG_DELAY_RPT_CMD_EVT                  /* delay report */
};

/* response message-to-event lookup table */
const UINT8 avdt_msg_rsp_2_evt[] = {
    AVDT_CCB_MSG_DISCOVER_RSP_EVT + AVDT_CCB_MKR,   /* discover */
    AVDT_CCB_MSG_GETCAP_RSP_EVT + AVDT_CCB_MKR,     /* get capabilities */
    AVDT_SCB_MSG_SETCONFIG_RSP_EVT,                 /* set configuration */
    AVDT_SCB_MSG_GETCONFIG_RSP_EVT,                 /* get configuration */
    AVDT_SCB_MSG_RECONFIG_RSP_EVT,                  /* reconfigure */
    AVDT_SCB_MSG_OPEN_RSP_EVT,                      /* open */
    AVDT_CCB_MSG_START_RSP_EVT + AVDT_CCB_MKR,      /* start */
    AVDT_SCB_MSG_CLOSE_RSP_EVT,                     /* close */
    AVDT_CCB_MSG_SUSPEND_RSP_EVT + AVDT_CCB_MKR,    /* suspend */
    AVDT_SCB_MSG_ABORT_RSP_EVT,                     /* abort */
    AVDT_SCB_MSG_SECURITY_RSP_EVT,                  /* security control */
    AVDT_CCB_MSG_GETCAP_RSP_EVT + AVDT_CCB_MKR,     /* get all capabilities */
    AVDT_SCB_MSG_DELAY_RPT_RSP_EVT                  /* delay report */
};

/* reject message-to-event lookup table */
const UINT8 avdt_msg_rej_2_evt[] = {
    AVDT_CCB_MSG_DISCOVER_RSP_EVT + AVDT_CCB_MKR,   /* discover */
    AVDT_CCB_MSG_GETCAP_RSP_EVT + AVDT_CCB_MKR,     /* get capabilities */
    AVDT_SCB_MSG_SETCONFIG_REJ_EVT,                 /* set configuration */
    AVDT_SCB_MSG_GETCONFIG_RSP_EVT,                 /* get configuration */
    AVDT_SCB_MSG_RECONFIG_RSP_EVT,                  /* reconfigure */
    AVDT_SCB_MSG_OPEN_REJ_EVT,                      /* open */
    AVDT_CCB_MSG_START_RSP_EVT + AVDT_CCB_MKR,      /* start */
    AVDT_SCB_MSG_CLOSE_RSP_EVT,                     /* close */
    AVDT_CCB_MSG_SUSPEND_RSP_EVT + AVDT_CCB_MKR,    /* suspend */
    AVDT_SCB_MSG_ABORT_RSP_EVT,                     /* abort */
    AVDT_SCB_MSG_SECURITY_RSP_EVT,                  /* security control */
    AVDT_CCB_MSG_GETCAP_RSP_EVT + AVDT_CCB_MKR,     /* get all capabilities */
    0                                               /* delay report */
};

/*******************************************************************************
**
** Function         avdt_msg_bld_cfg
**
** Description      This function builds the configuration parameters contained
**                  in a command or response message.
**
**
** Returns          void.
**
*******************************************************************************/
static void avdt_msg_bld_cfg(UINT8 **p, tAVDT_CFG *p_cfg)
{
    UINT8 len;

    /* for now, just build media transport, codec, and content protection, and multiplexing */

    /* media transport */
    if (p_cfg->psc_mask & AVDT_PSC_TRANS)
    {
        *(*p)++ = AVDT_CAT_TRANS;
        *(*p)++ = 0; /* length */
    }

#if AVDT_REPORTING == TRUE
    /* reporting transport */
    if (p_cfg->psc_mask & AVDT_PSC_REPORT)
    {
        *(*p)++ = AVDT_CAT_REPORT;
        *(*p)++ = 0; /* length */
    }
#endif

    /* codec */
    if (p_cfg->num_codec != 0)
    {
        *(*p)++ = AVDT_CAT_CODEC;
        len = p_cfg->codec_info[0] + 1;
        if( len > AVDT_CODEC_SIZE )
            len = AVDT_CODEC_SIZE;

        memcpy(*p, p_cfg->codec_info, len);
        *p += len;
    }

    /* content protection */
    if (p_cfg->num_protect != 0)
    {
        *(*p)++ = AVDT_CAT_PROTECT;
        len = p_cfg->protect_info[0] + 1;
        if( len > AVDT_PROTECT_SIZE )
            len = AVDT_PROTECT_SIZE;

        memcpy(*p, p_cfg->protect_info, len);
        *p += len;
    }

#if AVDT_MULTIPLEXING == TRUE
    /* multiplexing */
    if (p_cfg->psc_mask & AVDT_PSC_MUX)
    {
        *(*p)++ = AVDT_CAT_MUX;
        /* length */
        if (p_cfg->psc_mask & AVDT_PSC_RECOV)
            *(*p)++ = 7; /* frag (1) + media + report + recovery */
        else if (p_cfg->psc_mask & AVDT_PSC_REPORT)
            *(*p)++ = 5; /* frag (1) + media + report */
        else
            *(*p)++ = 3; /* frag (1) + media */

        /* allow fragmentation */
        if(p_cfg->mux_mask & AVDT_MUX_FRAG)
            *(*p)++ = 0x80;
        else
            *(*p)++ = 0;

        /* media transport session */
        *(*p)++ = p_cfg->mux_tsid_media<<3; /* TSID */
        *(*p)++ = p_cfg->mux_tcid_media<<3; /* TCID */

        if (p_cfg->psc_mask & AVDT_PSC_RECOV)
        {
            /* reporting transport session */
            *(*p)++ = p_cfg->mux_tsid_report<<3; /* TSID */
            *(*p)++ = p_cfg->mux_tcid_report<<3; /* TCID */
            /* recovery transport session */
            *(*p)++ = p_cfg->mux_tsid_recov<<3; /* TSID */
            *(*p)++ = p_cfg->mux_tcid_recov<<3; /* TCID */
        }
        else if (p_cfg->psc_mask & AVDT_PSC_REPORT)
        {
            /* reporting transport session */
            *(*p)++ = p_cfg->mux_tsid_report<<3; /* TSID */
            *(*p)++ = p_cfg->mux_tcid_report<<3; /* TCID */
        }
    }
#endif

    /* delay report */
    if (p_cfg->psc_mask & AVDT_PSC_DELAY_RPT)
    {
        *(*p)++ = AVDT_CAT_DELAY_RPT;
        *(*p)++ = 0; /* length */
    }
}

/*******************************************************************************
**
** Function         avdt_msg_bld_none
**
** Description      This message building function builds an empty message.
**
**
** Returns          void.
**
*******************************************************************************/
static void avdt_msg_bld_none(UINT8 **p, tAVDT_MSG *p_msg)
{
    return;
}

/*******************************************************************************
**
** Function         avdt_msg_bld_single
**
** Description      This message building function builds a message containing
**                  a single SEID.
**
**
** Returns          void.
**
*******************************************************************************/
static void avdt_msg_bld_single(UINT8 **p, tAVDT_MSG *p_msg)
{
    AVDT_MSG_BLD_SEID(*p, p_msg->single.seid);
}

/*******************************************************************************
**
** Function         avdt_msg_bld_setconfig_cmd
**
** Description      This message building function builds a set configuration
**                  command message.
**
**
** Returns          void.
**
*******************************************************************************/
static void avdt_msg_bld_setconfig_cmd(UINT8 **p, tAVDT_MSG *p_msg)
{
    AVDT_MSG_BLD_SEID(*p, p_msg->config_cmd.hdr.seid);
    AVDT_MSG_BLD_SEID(*p, p_msg->config_cmd.int_seid);
    avdt_msg_bld_cfg(p, p_msg->config_cmd.p_cfg);
}

/*******************************************************************************
**
** Function         avdt_msg_bld_reconfig_cmd
**
** Description      This message building function builds a reconfiguration
**                  command message.
**
**
** Returns          void.
**
*******************************************************************************/
static void avdt_msg_bld_reconfig_cmd(UINT8 **p, tAVDT_MSG *p_msg)
{
    AVDT_MSG_BLD_SEID(*p, p_msg->reconfig_cmd.hdr.seid);

    /* force psc mask zero to build only codec and security */
    p_msg->reconfig_cmd.p_cfg->psc_mask = 0;
    avdt_msg_bld_cfg(p, p_msg->reconfig_cmd.p_cfg);
}

/*******************************************************************************
**
** Function         avdt_msg_bld_multi
**
** Description      This message building function builds a message containing
**                  multiple SEID's.
**
**
** Returns          void.
**
*******************************************************************************/
static void avdt_msg_bld_multi(UINT8 **p, tAVDT_MSG *p_msg)
{
    int i;

    for (i = 0; i < p_msg->multi.num_seps; i++)
    {
        AVDT_MSG_BLD_SEID(*p, p_msg->multi.seid_list[i]);
    }
}

/*******************************************************************************
**
** Function         avdt_msg_bld_security_cmd
**
** Description      This message building function builds a security
**                  command message.
**
** Returns          void.
**
*******************************************************************************/
static void avdt_msg_bld_security_cmd(UINT8 **p, tAVDT_MSG *p_msg)
{
    AVDT_MSG_BLD_SEID(*p, p_msg->security_cmd.hdr.seid);
    memcpy(*p, p_msg->security_cmd.p_data, p_msg->security_cmd.len);
    *p += p_msg->security_cmd.len;
}

/*******************************************************************************
**
** Function         avdt_msg_bld_delay_rpt
**
** Description      This message building function builds a delay report
**                  command message.
**
** Returns          void.
**
*******************************************************************************/
static void avdt_msg_bld_delay_rpt(UINT8 **p, tAVDT_MSG *p_msg)
{
    AVDT_MSG_BLD_SEID(*p, p_msg->delay_rpt_cmd.hdr.seid);
    UINT16_TO_BE_STREAM(*p, p_msg->delay_rpt_cmd.delay);
}

/*******************************************************************************
**
** Function         avdt_msg_bld_discover_rsp
**
** Description      This message building function builds a discover
**                  response message.
**
**
** Returns          void.
**
*******************************************************************************/
static void avdt_msg_bld_discover_rsp(UINT8 **p, tAVDT_MSG *p_msg)
{
    int     i;

    for (i = 0; i < p_msg->discover_rsp.num_seps; i++)
    {
        /* build discover rsp info */
        AVDT_MSG_BLD_DISC(*p, p_msg->discover_rsp.p_sep_info[i].seid,
                              p_msg->discover_rsp.p_sep_info[i].in_use,
                              p_msg->discover_rsp.p_sep_info[i].media_type,
                              p_msg->discover_rsp.p_sep_info[i].tsep);
    }
}

/*******************************************************************************
**
** Function         avdt_msg_bld_svccap
**
** Description      This message building function builds a message containing
**                  service capabilities parameters.
**
**
** Returns          void.
**
*******************************************************************************/
static void avdt_msg_bld_svccap(UINT8 **p, tAVDT_MSG *p_msg)
{
    tAVDT_CFG cfg;

    /* make sure the delay report category is not reported */
    memcpy (&cfg, p_msg->svccap.p_cfg, sizeof(tAVDT_CFG));
    cfg.psc_mask &= ~AVDT_PSC_DELAY_RPT;
    avdt_msg_bld_cfg(p, &cfg);
}

/*******************************************************************************
**
** Function         avdt_msg_bld_all_svccap
**
** Description      This message building function builds a message containing
**                  service capabilities parameters.
**
**
** Returns          void.
**
*******************************************************************************/
static void avdt_msg_bld_all_svccap(UINT8 **p, tAVDT_MSG *p_msg)
{
    avdt_msg_bld_cfg(p, p_msg->svccap.p_cfg);
}

/*******************************************************************************
**
** Function         avdt_msg_bld_security_rsp
**
** Description      This message building function builds a security
**                  response message.
**
**
** Returns          void.
**
*******************************************************************************/
static void avdt_msg_bld_security_rsp(UINT8 **p, tAVDT_MSG *p_msg)
{
    memcpy(*p, p_msg->security_rsp.p_data, p_msg->security_rsp.len);
    *p += p_msg->security_rsp.len;
}

/*******************************************************************************
**
** Function         avdt_msg_prs_cfg
**
** Description      This message parsing function parses the configuration
**                  parameters field of a message.
**
**
** Returns          Error code or zero if no error, and element that failed
**                  in p_elem.
**
*******************************************************************************/
static UINT8 avdt_msg_prs_cfg(tAVDT_CFG *p_cfg, UINT8 *p, UINT16 len, UINT8* p_elem, UINT8 sig_id)
{
    UINT8   *p_end;
    UINT8   elem = 0;
    UINT8   elem_len;
    UINT8   tmp;
    UINT8   err = 0;
    UINT8   protect_offset = 0;

    if (!p_cfg)
    {
        AVDT_TRACE_ERROR0 ("not expecting this cfg");
        return AVDT_ERR_BAD_STATE;
    }

    p_cfg->psc_mask = 0;
    p_cfg->num_codec = 0;
    p_cfg->num_protect = 0;
#if AVDT_MULTIPLEXING == TRUE
    p_cfg->mux_mask = 0;
#endif

    /* while there is still data to parse */
    p_end = p + len;
    while ((p < p_end) && (err == 0))
    {
        /* verify overall length */
        if ((p_end - p) < AVDT_LEN_CFG_MIN)
        {
            err = AVDT_ERR_PAYLOAD;
            break;
        }

        /* get and verify info elem id, length */
        elem = *p++;
        elem_len = *p++;

        if ((elem == 0) || (elem > AVDT_CAT_MAX_CUR))
        {
            /* this may not be really bad.
             * It may be a service category that is too new for us.
             * allow these to be parsed without reporting an error.
             * If this is a "capability" (as in GetCapRsp & GetConfigRsp), this is filtered out.
             * If this is a Configuration (as in SetConfigCmd & ReconfigCmd),
             *    this will be marked as an error in the caller of this function */
            if ((sig_id == AVDT_SIG_SETCONFIG) || (sig_id == AVDT_SIG_RECONFIG))
            {
                /* Cannot accept unknown category. */
                err = AVDT_ERR_CATEGORY;
                break;
            }
            else    /* GETCAP or GET_ALLCAP */
            {
                /* Skip unknown categories. */
                p += elem_len;
                AVDT_TRACE_DEBUG2("skipping unknown service category=%d len: %d", elem, elem_len);
                continue;
            }
        }

        if ((elem_len > avdt_msg_ie_len_max[elem]) ||
            (elem_len < avdt_msg_ie_len_min[elem]))
        {
            err = avdt_msg_ie_err[elem];
            break;
        }

        /* add element to psc mask, but mask out codec or protect */
        p_cfg->psc_mask |= (1 << elem);
        AVDT_TRACE_DEBUG3("elem=%d elem_len: %d psc_mask=0x%x", elem, elem_len, p_cfg->psc_mask);

        /* parse individual information elements with additional parameters */
        switch (elem)
        {
            case AVDT_CAT_RECOV:
                p_cfg->recov_type = *p++;
                p_cfg->recov_mrws = *p++;
                p_cfg->recov_mnmp = *p++;
                if (p_cfg->recov_type != AVDT_RECOV_RFC2733)
                {
                    err = AVDT_ERR_RECOV_TYPE;
                }
                else if ((p_cfg->recov_mrws < AVDT_RECOV_MRWS_MIN) ||
                         (p_cfg->recov_mrws > AVDT_RECOV_MRWS_MAX) ||
                         (p_cfg->recov_mnmp < AVDT_RECOV_MNMP_MIN) ||
                         (p_cfg->recov_mnmp > AVDT_RECOV_MNMP_MAX))
                {
                    err = AVDT_ERR_RECOV_FMT;
                }
                break;

            case AVDT_CAT_PROTECT:
                p_cfg->psc_mask &= ~AVDT_PSC_PROTECT;
                if ((elem_len + protect_offset) < AVDT_PROTECT_SIZE)
                {
                    p_cfg->num_protect++;
                    p_cfg->protect_info[protect_offset] = elem_len;
                    protect_offset++;
                    memcpy(&p_cfg->protect_info[protect_offset], p, elem_len);
                    protect_offset += elem_len;
                }
                p += elem_len;
                break;

            case AVDT_CAT_HDRCMP:
                p_cfg->hdrcmp_mask = *p++;
                break;

#if AVDT_MULTIPLEXING == TRUE
            case AVDT_CAT_MUX:
                /* verify length */
                AVDT_TRACE_WARNING2("psc_mask=0x%x elem_len=%d", p_cfg->psc_mask, elem_len);
                if( ((0 == (p_cfg->psc_mask & (AVDT_PSC_RECOV|AVDT_PSC_REPORT))) && (elem_len != 3))
                    || ((p_cfg->psc_mask & AVDT_PSC_RECOV) && (elem_len != 7))
                    || ((p_cfg->psc_mask & AVDT_PSC_REPORT) && (elem_len != 5)) )
                {
                    err = AVDT_ERR_MUX_FMT;
                    break;
                }

                /* parse fragmentation */
                p_cfg->mux_mask = *p++ & (UINT8)AVDT_MUX_FRAG;

                /* parse TSIDs and TCIDs */
                if(--elem_len)
                    p_cfg->mux_tsid_media = (*p++)>>3;
                else
                    break;

                if(--elem_len)
                    p_cfg->mux_tcid_media = (*p++)>>3;
                else
                    break;

                if(--elem_len)
                    p_cfg->mux_tsid_report = (*p++)>>3;
                else
                    break;

                if(--elem_len)
                    p_cfg->mux_tcid_report = (*p++)>>3;
                else
                    break;

                if(--elem_len)
                    p_cfg->mux_tsid_recov = (*p++)>>3;
                else
                    break;

                if(--elem_len)
                    p_cfg->mux_tcid_recov = (*p++)>>3;
                else
                    break;
                break;
#endif

            case AVDT_CAT_CODEC:
                p_cfg->psc_mask &= ~AVDT_PSC_CODEC;
                tmp = elem_len;
                if (elem_len >= AVDT_CODEC_SIZE)
                {
                    tmp = AVDT_CODEC_SIZE - 1;
                }
                p_cfg->num_codec++;
                p_cfg->codec_info[0] = elem_len;
                memcpy(&p_cfg->codec_info[1], p, tmp);
                p += elem_len;
                break;

            case AVDT_CAT_DELAY_RPT:
                break;

            default:
                p += elem_len;
                break;
        } /* switch */
    } /* while ! err, !end*/
    *p_elem = elem;
    AVDT_TRACE_DEBUG3("err=0x%x, elem:0x%x psc_mask=0x%x", err, elem, p_cfg->psc_mask);

    return err;
}

/*******************************************************************************
**
** Function         avdt_msg_prs_none
**
** Description      This message parsing function parses a message with no parameters.

**
**
** Returns          Error code or zero if no error.
**
*******************************************************************************/
static UINT8 avdt_msg_prs_none(tAVDT_MSG *p_msg, UINT8 *p, UINT16 len)
{
    return 0;
}

/*******************************************************************************
**
** Function         avdt_msg_prs_single
**
** Description      This message parsing function parses a message with a
**                  single SEID.
**
**
** Returns          Error code or zero if no error.
**
*******************************************************************************/
static UINT8 avdt_msg_prs_single(tAVDT_MSG *p_msg, UINT8 *p, UINT16 len)
{
    UINT8       err = 0;

    /* verify len */
    if (len != AVDT_LEN_SINGLE)
    {
        err = AVDT_ERR_LENGTH;
    }
    else
    {
        AVDT_MSG_PRS_SEID(p, p_msg->single.seid);

        if (avdt_scb_by_hdl(p_msg->single.seid) == NULL)
        {
            err = AVDT_ERR_SEID;
        }
    }
    return err;
}

/*******************************************************************************
**
** Function         avdt_msg_prs_setconfig_cmd
**
** Description      This message parsing function parses a set configuration
**                  command message.
**
**
** Returns          Error code or zero if no error.
**
*******************************************************************************/
static UINT8 avdt_msg_prs_setconfig_cmd(tAVDT_MSG *p_msg, UINT8 *p, UINT16 len)
{
    UINT8       err = 0;

    p_msg->hdr.err_param = 0;

    /* verify len */
    if (len < AVDT_LEN_SETCONFIG_MIN)
    {
        err = AVDT_ERR_LENGTH;
    }
    else
    {
        /* get seids */
        AVDT_MSG_PRS_SEID(p, p_msg->config_cmd.hdr.seid);
        if (avdt_scb_by_hdl(p_msg->config_cmd.hdr.seid) == NULL)
        {
            err = AVDT_ERR_SEID;
        }

        AVDT_MSG_PRS_SEID(p, p_msg->config_cmd.int_seid);
        if ((p_msg->config_cmd.int_seid < AVDT_SEID_MIN) ||
            (p_msg->config_cmd.int_seid > AVDT_SEID_MAX))
        {
            err = AVDT_ERR_SEID;
        }
    }

    if (!err)
    {
        /* parse configuration parameters */
        len -= 2;
        err = avdt_msg_prs_cfg(p_msg->config_cmd.p_cfg, p, len, &p_msg->hdr.err_param, AVDT_SIG_SETCONFIG);

        if (!err)
        {
            /* verify protocol service capabilities are supported */
            if (((p_msg->config_cmd.p_cfg->psc_mask & (~AVDT_PSC)) != 0) ||
                (p_msg->config_cmd.p_cfg->num_codec == 0))
            {
                err = AVDT_ERR_INVALID_CAP;
            }
        }
    }

    return err;
}

/*******************************************************************************
**
** Function         avdt_msg_prs_reconfig_cmd
**
** Description      This message parsing function parses a reconfiguration
**                  command message.
**
**
** Returns          Error code or zero if no error.
**
*******************************************************************************/
static UINT8 avdt_msg_prs_reconfig_cmd(tAVDT_MSG *p_msg, UINT8 *p, UINT16 len)
{
    UINT8       err = 0;

    p_msg->hdr.err_param = 0;

    /* verify len */
    if (len < AVDT_LEN_RECONFIG_MIN)
    {
        err = AVDT_ERR_LENGTH;
    }
    else
    {
        /* get seid */
        AVDT_MSG_PRS_SEID(p, p_msg->reconfig_cmd.hdr.seid);
        if (avdt_scb_by_hdl(p_msg->reconfig_cmd.hdr.seid) == NULL)
        {
            err = AVDT_ERR_SEID;
        }
        else
        {
            /* parse config parameters */
            len--;
            err = avdt_msg_prs_cfg(p_msg->config_cmd.p_cfg, p, len, &p_msg->hdr.err_param, AVDT_SIG_RECONFIG);

            /* verify no protocol service capabilities in parameters */
            if (!err)
            {
                AVDT_TRACE_DEBUG2("avdt_msg_prs_reconfig_cmd psc_mask=0x%x/0x%x", p_msg->config_cmd.p_cfg->psc_mask, AVDT_MSG_PSC_MASK);
                if ((p_msg->config_cmd.p_cfg->psc_mask != 0) ||
                    (p_msg->config_cmd.p_cfg->num_codec == 0 && p_msg->config_cmd.p_cfg->num_protect == 0))
                {
                    err = AVDT_ERR_INVALID_CAP;
                }
            }
        }
    }
    return err;
}

/*******************************************************************************
**
** Function         avdt_msg_prs_multi
**
** Description      This message parsing function parses a message containing
**                  multiple SEID's.
**
**
** Returns          Error code or zero if no error.
**
*******************************************************************************/
static UINT8 avdt_msg_prs_multi(tAVDT_MSG *p_msg, UINT8 *p, UINT16 len)
{
    int     i;
    UINT8   err = 0;

    p_msg->hdr.err_param = 0;

    /* verify len */
    if (len < AVDT_LEN_MULTI_MIN || (len > AVDT_NUM_SEPS))
    {
        err = AVDT_ERR_LENGTH;
    }
    else
    {
        /* get and verify all seps */
        for (i = 0; i < len; i++)
        {
            AVDT_MSG_PRS_SEID(p, p_msg->multi.seid_list[i]);
            if (avdt_scb_by_hdl(p_msg->multi.seid_list[i]) == NULL)
            {
                err = AVDT_ERR_SEID;
                p_msg->hdr.err_param = p_msg->multi.seid_list[i];
                break;
            }
        }
        p_msg->multi.num_seps = (UINT8)i;
    }

    return err;
}

/*******************************************************************************
**
** Function         avdt_msg_prs_security_cmd
**
** Description      This message parsing function parses a security
**                  command message.
**
**
** Returns          Error code or zero if no error.
**
*******************************************************************************/
static UINT8 avdt_msg_prs_security_cmd(tAVDT_MSG *p_msg, UINT8 *p, UINT16 len)
{
    UINT8       err = 0;

    /* verify len */
    if (len < AVDT_LEN_SECURITY_MIN)
    {
        err = AVDT_ERR_LENGTH;
    }
    else
    {
        /* get seid */
        AVDT_MSG_PRS_SEID(p, p_msg->security_cmd.hdr.seid);
        if (avdt_scb_by_hdl(p_msg->security_cmd.hdr.seid) == NULL)
        {
            err = AVDT_ERR_SEID;
        }
        else
        {
            p_msg->security_cmd.p_data = p;
            p_msg->security_cmd.len = len - 1;
        }
    }
    return err;
}

/*******************************************************************************
**
** Function         avdt_msg_prs_discover_rsp
**
** Description      This message parsing function parses a discover
**                  response message.
**
**
** Returns          Error code or zero if no error.
**
*******************************************************************************/
static UINT8 avdt_msg_prs_discover_rsp(tAVDT_MSG *p_msg, UINT8 *p, UINT16 len)
{
    int     i;
    UINT8   err = 0;

    /* determine number of seps; seps in msg is len/2, but set to minimum
    ** of seps app has supplied memory for and seps in msg
    */
    if (p_msg->discover_rsp.num_seps > (len / 2))
    {
        p_msg->discover_rsp.num_seps = (len / 2);
    }

    /* parse out sep info */
    for (i = 0; i < p_msg->discover_rsp.num_seps; i++)
    {
        /* parse discover rsp info */
        AVDT_MSG_PRS_DISC(p, p_msg->discover_rsp.p_sep_info[i].seid,
                          p_msg->discover_rsp.p_sep_info[i].in_use,
                          p_msg->discover_rsp.p_sep_info[i].media_type,
                          p_msg->discover_rsp.p_sep_info[i].tsep);

        /* verify that seid is valid */
        if ((p_msg->discover_rsp.p_sep_info[i].seid < AVDT_SEID_MIN) ||
            (p_msg->discover_rsp.p_sep_info[i].seid > AVDT_SEID_MAX))
        {
            err = AVDT_ERR_SEID;
            break;
        }
    }

    return err;
}

/*******************************************************************************
**
** Function         avdt_msg_prs_svccap
**
** Description      This message parsing function parses a message containing
**                  service capabilities parameters.
**
**
** Returns          Error code or zero if no error.
**
*******************************************************************************/
static UINT8 avdt_msg_prs_svccap(tAVDT_MSG *p_msg, UINT8 *p, UINT16 len)
{
    /* parse parameters */
    UINT8   err = avdt_msg_prs_cfg(p_msg->svccap.p_cfg, p, len, &p_msg->hdr.err_param, AVDT_SIG_GETCAP);
    if (p_msg->svccap.p_cfg)
    {
        p_msg->svccap.p_cfg->psc_mask &= AVDT_LEG_PSC;
    }

    return (err);
}

/*******************************************************************************
**
** Function         avdt_msg_prs_all_svccap
**
** Description      This message parsing function parses a message containing
**                  service capabilities parameters.
**
**
** Returns          Error code or zero if no error.
**
*******************************************************************************/
static UINT8 avdt_msg_prs_all_svccap(tAVDT_MSG *p_msg, UINT8 *p, UINT16 len)
{
    UINT8   err = avdt_msg_prs_cfg(p_msg->svccap.p_cfg, p, len, &p_msg->hdr.err_param, AVDT_SIG_GET_ALLCAP);
    if (p_msg->svccap.p_cfg)
    {
        p_msg->svccap.p_cfg->psc_mask &= AVDT_MSG_PSC_MASK;
    }
    return (err);
}

/*******************************************************************************
**
** Function         avdt_msg_prs_security_rsp
**
** Description      This message parsing function parsing a security
**                  response message.
**
**
** Returns          Error code or zero if no error.
**
*******************************************************************************/
static UINT8 avdt_msg_prs_security_rsp(tAVDT_MSG *p_msg, UINT8 *p, UINT16 len)
{
    p_msg->security_rsp.p_data = p;
    p_msg->security_rsp.len = len;

    return 0;
}

/*******************************************************************************
**
** Function         avdt_msg_prs_rej
**
** Description
**
**
** Returns          Error code or zero if no error.
**
*******************************************************************************/
static UINT8 avdt_msg_prs_rej(tAVDT_MSG *p_msg, UINT8 *p, UINT8 sig)
{
    if ((sig == AVDT_SIG_SETCONFIG) || (sig == AVDT_SIG_RECONFIG))
    {
        p_msg->hdr.err_param = *p++;
        p_msg->hdr.err_code = *p;
    }
    else if ((sig == AVDT_SIG_START) || (sig == AVDT_SIG_SUSPEND))
    {
        AVDT_MSG_PRS_SEID(p, p_msg->hdr.err_param);
        p_msg->hdr.err_code = *p;
    }
    else
    {
        p_msg->hdr.err_code = *p;
    }

    return 0;
}

/*******************************************************************************
**
** Function         avdt_msg_prs_delay_rpt
**
** Description      This message parsing function parses a security
**                  command message.
**
**
** Returns          Error code or zero if no error.
**
*******************************************************************************/
static UINT8 avdt_msg_prs_delay_rpt (tAVDT_MSG *p_msg, UINT8 *p, UINT16 len)
{
    UINT8       err = 0;

    /* verify len */
    if (len != AVDT_LEN_DELAY_RPT)
    {
        AVDT_TRACE_WARNING2("avdt_msg_prs_delay_rpt expected len: %u  got: %u", AVDT_LEN_DELAY_RPT, len);
        err = AVDT_ERR_LENGTH;
    }
    else
    {
        /* get seid */
        AVDT_MSG_PRS_SEID (p, p_msg->delay_rpt_cmd.hdr.seid);

        if (avdt_scb_by_hdl(p_msg->delay_rpt_cmd.hdr.seid) == NULL)
        {
            err = AVDT_ERR_SEID;
        }
        else
        {
            BE_STREAM_TO_UINT16 (p_msg->delay_rpt_cmd.delay, p);
            AVDT_TRACE_DEBUG1("avdt_msg_prs_delay_rpt delay: %u", p_msg->delay_rpt_cmd.delay);
        }
    }
    return err;
}


/*******************************************************************************
**
** Function         avdt_msg_send
**
** Description      Send, and if necessary fragment the next message.
**
**
** Returns          Congested state; TRUE if CCB congested, FALSE if not.
**
*******************************************************************************/
BOOLEAN avdt_msg_send(tAVDT_CCB *p_ccb, BT_HDR *p_msg)
{
    UINT16          curr_msg_len;
    UINT8           pkt_type;
    UINT8           hdr_len;
    tAVDT_TC_TBL    *p_tbl;
    BT_HDR          *p_buf;
    UINT8           *p;
    UINT8           label;
    UINT8           msg;
    UINT8           sig;
    UINT8           nosp = 0;       /* number of subsequent packets */

    /* look up transport channel table entry to get peer mtu */
    p_tbl = avdt_ad_tc_tbl_by_type(AVDT_CHAN_SIG, p_ccb, NULL);

    /* set the current message if there is a message passed in */
    if (p_msg != NULL)
    {
        p_ccb->p_curr_msg = p_msg;
    }

    /* store copy of curr_msg->len */
    curr_msg_len = p_ccb->p_curr_msg->len;

    /* while not congested and we haven't sent it all */
    while ((!p_ccb->cong) && (p_ccb->p_curr_msg != NULL))
    {
        /* check what kind of message we've got here; we are using the offset
        ** to indicate that a message is being fragmented
        */

        /* if message isn't being fragmented and it fits in mtu */
        if ((p_ccb->p_curr_msg->offset == AVDT_MSG_OFFSET) &&
            (p_ccb->p_curr_msg->len <= p_tbl->peer_mtu - AVDT_LEN_TYPE_SINGLE))
        {
            pkt_type = AVDT_PKT_TYPE_SINGLE;
            hdr_len = AVDT_LEN_TYPE_SINGLE;
            p_buf = p_ccb->p_curr_msg;
        }
        /* if message isn't being fragmented and it doesn't fit in mtu */
        else if ((p_ccb->p_curr_msg->offset == AVDT_MSG_OFFSET) &&
                 (p_ccb->p_curr_msg->len > p_tbl->peer_mtu - AVDT_LEN_TYPE_SINGLE))
        {
            pkt_type = AVDT_PKT_TYPE_START;
            hdr_len = AVDT_LEN_TYPE_START;
            nosp = (p_ccb->p_curr_msg->len + AVDT_LEN_TYPE_START - p_tbl->peer_mtu) /
                   (p_tbl->peer_mtu - 1) + 2;

            /* get a new buffer for fragment we are sending */
            if ((p_buf = (BT_HDR *) GKI_getpoolbuf(AVDT_CMD_POOL_ID)) == NULL)
            {
                /* do we even want to try and recover from this? could do so
                by setting retransmission timer */
                return TRUE;
            }

            /* copy portion of data from current message to new buffer */
            p_buf->offset = L2CAP_MIN_OFFSET + hdr_len;
            p_buf->len = p_tbl->peer_mtu - hdr_len;
            memcpy((UINT8 *)(p_buf + 1) + p_buf->offset,
                   (UINT8 *)(p_ccb->p_curr_msg + 1) + p_ccb->p_curr_msg->offset, p_buf->len);
        }
        /* if message is being fragmented and remaining bytes don't fit in mtu */
        else if ((p_ccb->p_curr_msg->offset > AVDT_MSG_OFFSET) &&
                 (p_ccb->p_curr_msg->len > (p_tbl->peer_mtu - AVDT_LEN_TYPE_CONT)))
        {
            pkt_type = AVDT_PKT_TYPE_CONT;
            hdr_len = AVDT_LEN_TYPE_CONT;

            /* get a new buffer for fragment we are sending */
            if ((p_buf = (BT_HDR *) GKI_getpoolbuf(AVDT_CMD_POOL_ID)) == NULL)
            {
                /* do we even want to try and recover from this? could do so
                by setting retransmission timer */
                return TRUE;
            }

            /* copy portion of data from current message to new buffer */
            p_buf->offset = L2CAP_MIN_OFFSET + hdr_len;
            p_buf->len = p_tbl->peer_mtu - hdr_len;
            memcpy((UINT8 *)(p_buf + 1) + p_buf->offset,
                   (UINT8 *)(p_ccb->p_curr_msg + 1) + p_ccb->p_curr_msg->offset, p_buf->len);
        }
        /* if message is being fragmented and remaining bytes do fit in mtu */
        else
        {
            pkt_type = AVDT_PKT_TYPE_END;
            hdr_len = AVDT_LEN_TYPE_END;
            p_buf = p_ccb->p_curr_msg;
        }

        /* label, sig id, msg type are in hdr of p_curr_msg */
        label = AVDT_LAYERSPEC_LABEL(p_ccb->p_curr_msg->layer_specific);
        msg = AVDT_LAYERSPEC_MSG(p_ccb->p_curr_msg->layer_specific);
        sig = (UINT8) p_ccb->p_curr_msg->event;
        AVDT_TRACE_DEBUG3("avdt_msg_send label:%d, msg:%d, sig:%d", label, msg, sig);

        /* keep track of how much of msg we've sent */
        curr_msg_len -= p_buf->len;
        if (curr_msg_len == 0)
        {
            /* entire message sent; mark as finished */
            p_ccb->p_curr_msg = NULL;

            /* start timer here for commands */
            if (msg == AVDT_MSG_TYPE_CMD)
            {
                /* if retransmit timeout set to zero, sig doesn't use retransmit */
                if ((sig == AVDT_SIG_DISCOVER) || (sig == AVDT_SIG_GETCAP) ||
                    (sig == AVDT_SIG_SECURITY) || (avdt_cb.rcb.ret_tout == 0))
                {
                    btu_start_timer(&p_ccb->timer_entry, BTU_TTYPE_AVDT_CCB_RSP, avdt_cb.rcb.sig_tout);
                }
                else if (sig != AVDT_SIG_DELAY_RPT)
                {
                    btu_start_timer(&p_ccb->timer_entry, BTU_TTYPE_AVDT_CCB_RET, avdt_cb.rcb.ret_tout);
                }
            }
        }
        else
        {
            /* message being fragmented and not completely sent */
            p_ccb->p_curr_msg->len -= p_buf->len;
            p_ccb->p_curr_msg->offset += p_buf->len;
        }

        /* set up to build header */
        p_buf->len += hdr_len;
        p_buf->offset -= hdr_len;
        p = (UINT8 *)(p_buf + 1) + p_buf->offset;

        /* build header */
        AVDT_MSG_BLD_HDR(p, label, pkt_type, msg);
        if (pkt_type == AVDT_PKT_TYPE_START)
        {
            AVDT_MSG_BLD_NOSP(p, nosp);
        }
        if ((pkt_type == AVDT_PKT_TYPE_START) || (pkt_type == AVDT_PKT_TYPE_SINGLE))
        {
            AVDT_MSG_BLD_SIG(p, sig);
        }

        /* send msg buffer down */
        avdt_ad_write_req(AVDT_CHAN_SIG, p_ccb, NULL, p_buf);
    }
    return (p_ccb->cong);
}

/*******************************************************************************
**
** Function         avdt_msg_asmbl
**
** Description      Reassemble incoming message.
**
**
** Returns          Pointer to reassembled message;  NULL if no message
**                  available.
**
*******************************************************************************/
BT_HDR *avdt_msg_asmbl(tAVDT_CCB *p_ccb, BT_HDR *p_buf)
{
    UINT8   *p;
    UINT8   pkt_type;
    BT_HDR  *p_ret;
    UINT16  buf_len;

    /* parse the message header */
    p = (UINT8 *)(p_buf + 1) + p_buf->offset;
    AVDT_MSG_PRS_PKT_TYPE(p, pkt_type);

    /* quick sanity check on length */
    if (p_buf->len < avdt_msg_pkt_type_len[pkt_type])
    {
        GKI_freebuf(p_buf);
        AVDT_TRACE_WARNING0("Bad length during reassembly");
        p_ret = NULL;
    }
    /* single packet */
    else if (pkt_type == AVDT_PKT_TYPE_SINGLE)
    {
        /* if reassembly in progress drop message and process new single */
        if (p_ccb->p_rx_msg != NULL)
        {
            GKI_freebuf(p_ccb->p_rx_msg);
            p_ccb->p_rx_msg = NULL;
            AVDT_TRACE_WARNING0("Got single during reassembly");
        }
        p_ret = p_buf;
    }
    /* start packet */
    else if (pkt_type == AVDT_PKT_TYPE_START)
    {
        /* if reassembly in progress drop message and process new single */
        if (p_ccb->p_rx_msg != NULL)
        {
            GKI_freebuf(p_ccb->p_rx_msg);
            AVDT_TRACE_WARNING0("Got start during reassembly");
        }
        p_ccb->p_rx_msg = p_buf;

        /* copy first header byte over nosp */
        *(p + 1) = *p;

        /* set offset to point to where to copy next */
        p_ccb->p_rx_msg->offset += p_ccb->p_rx_msg->len;

        /* adjust length for packet header */
        p_ccb->p_rx_msg->len -= 1;

        p_ret = NULL;
    }
    /* continue or end */
    else
    {
        /* if no reassembly in progress drop message */
        if (p_ccb->p_rx_msg == NULL)
        {
            GKI_freebuf(p_buf);
            AVDT_TRACE_WARNING1("Pkt type=%d out of order", pkt_type);
            p_ret = NULL;
        }
        else
        {
            /* get size of buffer holding assembled message */
            buf_len = GKI_get_buf_size(p_ccb->p_rx_msg) - sizeof(BT_HDR);

            /* adjust offset and len of fragment for header byte */
            p_buf->offset += AVDT_LEN_TYPE_CONT;
            p_buf->len -= AVDT_LEN_TYPE_CONT;

            /* verify length */
            if ((p_ccb->p_rx_msg->offset + p_buf->len) > buf_len)
            {
                /* won't fit; free everything */
                GKI_freebuf(p_ccb->p_rx_msg);
                p_ccb->p_rx_msg = NULL;
                GKI_freebuf(p_buf);
                p_ret = NULL;
            }
            else
            {
                /* copy contents of p_buf to p_rx_msg */
                memcpy((UINT8 *)(p_ccb->p_rx_msg + 1) + p_ccb->p_rx_msg->offset,
                       (UINT8 *)(p_buf + 1) + p_buf->offset, p_buf->len);

                if (pkt_type == AVDT_PKT_TYPE_END)
                {
                    p_ccb->p_rx_msg->offset -= p_ccb->p_rx_msg->len;
                    p_ccb->p_rx_msg->len += p_buf->len;
                    p_ret = p_ccb->p_rx_msg;
                    p_ccb->p_rx_msg = NULL;
                }
                else
                {
                    p_ccb->p_rx_msg->offset += p_buf->len;
                    p_ccb->p_rx_msg->len += p_buf->len;
                    p_ret = NULL;
                }
                GKI_freebuf(p_buf);
            }
        }
    }
    return p_ret;
}

/*******************************************************************************
**
** Function         avdt_msg_send_cmd
**
** Description      This function is called to send a command message.  The
**                  sig_id parameter indicates the message type, p_params
**                  points to the message parameters, if any.  It gets a buffer
**                  from the AVDTP command pool, executes the message building
**                  function for this message type.  It then queues the message
**                  in the command queue for this CCB.
**
**
** Returns          Nothing.
**
*******************************************************************************/
void avdt_msg_send_cmd(tAVDT_CCB *p_ccb, void *p_scb, UINT8 sig_id, tAVDT_MSG *p_params)
{
    BT_HDR      *p_buf;
    UINT8       *p;
    UINT8       *p_start;

    /* get a buffer */
    p_buf = (BT_HDR *) GKI_getpoolbuf(AVDT_CMD_POOL_ID);
    if (p_buf == NULL)
    {
        AVDT_TRACE_ERROR0("avdt_msg_send_cmd out of buffer!!");
        return;
    }

    /* set up gki buf pointer and offset */
    p_buf->offset = AVDT_MSG_OFFSET;
    p_start = p = (UINT8 *)(p_buf + 1) + p_buf->offset;

    /* execute parameter building function to build message */
    (*avdt_msg_bld_cmd[sig_id - 1])(&p, p_params);

    /* set len */
    p_buf->len = (UINT16) (p - p_start);

    /* now store scb hdls, if any, in buf */
    if (p_scb != NULL)
    {
        p = (UINT8 *)(p_buf + 1);

        /* for start and suspend, p_scb points to array of handles */
        if ((sig_id == AVDT_SIG_START) || (sig_id == AVDT_SIG_SUSPEND))
        {
            memcpy(p, (UINT8 *) p_scb, p_buf->len);
        }
        /* for all others, p_scb points to scb as usual */
        else
        {
            *p = avdt_scb_to_hdl((tAVDT_SCB *) p_scb);
        }
    }

    /* stash sig, label, and message type in buf */
    p_buf->event = sig_id;
    AVDT_BLD_LAYERSPEC(p_buf->layer_specific, AVDT_MSG_TYPE_CMD, p_ccb->label);

    /* increment label */
    p_ccb->label = (p_ccb->label + 1) % 16;

    /* queue message and trigger ccb to send it */
    GKI_enqueue(&p_ccb->cmd_q, p_buf);
    avdt_ccb_event(p_ccb, AVDT_CCB_SENDMSG_EVT, NULL);
}


/*******************************************************************************
**
** Function         avdt_msg_send_rsp
**
** Description      This function is called to send a response message.  The
**                  sig_id parameter indicates the message type, p_params
**                  points to the message parameters, if any.  It gets a buffer
**                  from the AVDTP command pool, executes the message building
**                  function for this message type.  It then queues the message
**                  in the response queue for this CCB.
**
**
** Returns          Nothing.
**
*******************************************************************************/
void avdt_msg_send_rsp(tAVDT_CCB *p_ccb, UINT8 sig_id, tAVDT_MSG *p_params)
{
    BT_HDR      *p_buf;
    UINT8       *p;
    UINT8       *p_start;

    /* get a buffer */
    p_buf = (BT_HDR *) GKI_getpoolbuf(AVDT_CMD_POOL_ID);
    if (p_buf == NULL) return;

    /* set up gki buf pointer and offset */
    p_buf->offset = AVDT_MSG_OFFSET;
    p_start = p = (UINT8 *)(p_buf + 1) + p_buf->offset;

    /* execute parameter building function to build message */
    (*avdt_msg_bld_rsp[sig_id - 1])(&p, p_params);

    /* set length */
    p_buf->len = (UINT16) (p - p_start);

    /* stash sig, label, and message type in buf */
    p_buf->event = sig_id;
    AVDT_BLD_LAYERSPEC(p_buf->layer_specific, AVDT_MSG_TYPE_RSP, p_params->hdr.label);

    /* queue message and trigger ccb to send it */
    GKI_enqueue(&p_ccb->rsp_q, p_buf);
    avdt_ccb_event(p_ccb, AVDT_CCB_SENDMSG_EVT, NULL);
}


/*******************************************************************************
**
** Function         avdt_msg_send_rej
**
** Description      This function is called to send a reject message.  The
**                  sig_id parameter indicates the message type.  It gets
**                  a buffer from the AVDTP command pool and builds the
**                  message based on the message type and the error code.
**                  It then queues the message in the response queue for
**                  this CCB.
**
**
** Returns          Nothing.
**
*******************************************************************************/
void avdt_msg_send_rej(tAVDT_CCB *p_ccb, UINT8 sig_id, tAVDT_MSG *p_params)
{
    BT_HDR      *p_buf;
    UINT8       *p;
    UINT8       *p_start;

    /* get a buffer */
    p_buf = (BT_HDR *) GKI_getpoolbuf(AVDT_CMD_POOL_ID);
    if (p_buf == NULL) return;

    /* set up gki buf pointer and offset */
    p_buf->offset = AVDT_MSG_OFFSET;
    p_start = p = (UINT8 *)(p_buf + 1) + p_buf->offset;

    /* if sig id included, build into message */
    if (sig_id != AVDT_SIG_NONE)
    {
        /* if this sig has a parameter, add the parameter */
        if ((sig_id == AVDT_SIG_SETCONFIG) ||
            (sig_id == AVDT_SIG_RECONFIG))
        {
            AVDT_MSG_BLD_PARAM(p, p_params->hdr.err_param);
        }
        else if ((sig_id == AVDT_SIG_START) ||
                 (sig_id == AVDT_SIG_SUSPEND))
        {
            AVDT_MSG_BLD_SEID(p, p_params->hdr.err_param);
        }

        /* add the error code */
        AVDT_MSG_BLD_ERR(p, p_params->hdr.err_code);
    }
    AVDT_TRACE_DEBUG0("avdt_msg_send_rej");

    /* calculate length */
    p_buf->len = (UINT16) (p - p_start);

    /* stash sig, label, and message type in buf */
    p_buf->event = sig_id;
    AVDT_BLD_LAYERSPEC(p_buf->layer_specific, AVDT_MSG_TYPE_REJ, p_params->hdr.label);

    /* queue message and trigger ccb to send it */
    GKI_enqueue(&p_ccb->rsp_q, p_buf);
    avdt_ccb_event(p_ccb, AVDT_CCB_SENDMSG_EVT, NULL);
}

/*******************************************************************************
**
** Function         avdt_msg_send_grej
**
** Description      This function is called to send a general reject message.  The
**                  sig_id parameter indicates the message type.  It gets
**                  a buffer from the AVDTP command pool and builds the
**                  message based on the message type and the error code.
**                  It then queues the message in the response queue for
**                  this CCB.
**
**
** Returns          Nothing.
**
*******************************************************************************/
void avdt_msg_send_grej(tAVDT_CCB *p_ccb, UINT8 sig_id, tAVDT_MSG *p_params)
{
    BT_HDR      *p_buf;
    UINT8       *p;
    UINT8       *p_start;

    /* get a buffer */
    p_buf = (BT_HDR *) GKI_getpoolbuf(AVDT_CMD_POOL_ID);
    if (p_buf == NULL) return;

    /* set up gki buf pointer and offset */
    p_buf->offset = AVDT_MSG_OFFSET;
    p_start = p = (UINT8 *)(p_buf + 1) + p_buf->offset;

    /* calculate length */
    p_buf->len = (UINT16) (p - p_start);

    /* stash sig, label, and message type in buf */
    p_buf->event = sig_id;
    AVDT_BLD_LAYERSPEC(p_buf->layer_specific, AVDT_MSG_TYPE_GRJ, p_params->hdr.label);
    //p_buf->event = 0;
    //AVDT_BLD_LAYERSPEC(p_buf->layer_specific, 0, p_params->hdr.label);
    AVDT_TRACE_DEBUG0("avdt_msg_send_grej");

    /* queue message and trigger ccb to send it */
    GKI_enqueue(&p_ccb->rsp_q, p_buf);
    avdt_ccb_event(p_ccb, AVDT_CCB_SENDMSG_EVT, NULL);
}

/*******************************************************************************
**
** Function         avdt_msg_ind
**
** Description      This function is called by the adaption layer when an
**                  incoming message is received on the signaling channel.
**                  It parses the message and sends an event to the appropriate
**                  SCB or CCB for the message.
**
**
** Returns          Nothing.
**
*******************************************************************************/
void avdt_msg_ind(tAVDT_CCB *p_ccb, BT_HDR *p_buf)
{
    tAVDT_SCB   *p_scb;
    UINT8       *p;
    BOOLEAN     ok = TRUE;
    BOOLEAN     handle_rsp = FALSE;
    BOOLEAN     gen_rej = FALSE;
    UINT8       label;
    UINT8       pkt_type;
    UINT8       msg_type;
    UINT8       sig = 0;
    tAVDT_MSG   msg;
    tAVDT_CFG   cfg;
    UINT8       err;
    UINT8       evt = 0;
    UINT8       scb_hdl;

    /* reassemble message; if no message available (we received a fragment) return */
    if ((p_buf = avdt_msg_asmbl(p_ccb, p_buf)) == NULL)
    {
        return;
    }

    p = (UINT8 *)(p_buf + 1) + p_buf->offset;

    /* parse the message header */
    AVDT_MSG_PRS_HDR(p, label, pkt_type, msg_type);

    /* AVDT_TRACE_DEBUG1("msg_type=%d", msg_type); */
    /* set up label and ccb_idx in message hdr */
    msg.hdr.label = label;
    msg.hdr.ccb_idx = avdt_ccb_to_idx(p_ccb);

    /* verify msg type */
    if (msg_type == AVDT_MSG_TYPE_GRJ)
    {
        AVDT_TRACE_WARNING1("Dropping msg msg_type=%d", msg_type);
        ok = FALSE;
    }
    /* check for general reject */
    else if ((msg_type == AVDT_MSG_TYPE_REJ) && (p_buf->len == AVDT_LEN_GEN_REJ))
    {
        gen_rej = TRUE;
        if (p_ccb->p_curr_cmd != NULL)
        {
            msg.hdr.sig_id = sig = (UINT8) p_ccb->p_curr_cmd->event;
            evt = avdt_msg_rej_2_evt[sig - 1];
            msg.hdr.err_code = AVDT_ERR_NSC;
            msg.hdr.err_param = 0;
        }
    }
    else /* not a general reject */
    {
        /* get and verify signal */
        AVDT_MSG_PRS_SIG(p, sig);
        msg.hdr.sig_id = sig;
        if ((sig == 0) || (sig > AVDT_SIG_MAX))
        {
            AVDT_TRACE_WARNING2("Dropping msg sig=%d msg_type:%d", sig, msg_type);
            ok = FALSE;

            /* send a general reject */
            if (msg_type == AVDT_MSG_TYPE_CMD)
            {
                avdt_msg_send_grej(p_ccb, sig, &msg);
            }
        }
    }

    if (ok && !gen_rej)
    {
        /* skip over header (msg length already verified during reassembly) */
        p_buf->len -= AVDT_LEN_TYPE_SINGLE;

        /* set up to parse message */
        if ((msg_type == AVDT_MSG_TYPE_RSP) && (sig == AVDT_SIG_DISCOVER))
        {
            /* parse discover rsp message to struct supplied by app */
            msg.discover_rsp.p_sep_info = (tAVDT_SEP_INFO *) p_ccb->p_proc_data;
            msg.discover_rsp.num_seps = p_ccb->proc_param;
        }
        else if ((msg_type == AVDT_MSG_TYPE_RSP) &&
            ((sig == AVDT_SIG_GETCAP) || (sig == AVDT_SIG_GET_ALLCAP)))
        {
            /* parse discover rsp message to struct supplied by app */
            msg.svccap.p_cfg = (tAVDT_CFG *) p_ccb->p_proc_data;
        }
        else if ((msg_type == AVDT_MSG_TYPE_RSP) && (sig == AVDT_SIG_GETCONFIG))
        {
            /* parse get config rsp message to struct allocated locally */
            msg.svccap.p_cfg = &cfg;
        }
        else if ((msg_type == AVDT_MSG_TYPE_CMD) && (sig == AVDT_SIG_SETCONFIG))
        {
            /* parse config cmd message to struct allocated locally */
            msg.config_cmd.p_cfg = &cfg;
        }
        else if ((msg_type == AVDT_MSG_TYPE_CMD) && (sig == AVDT_SIG_RECONFIG))
        {
            /* parse reconfig cmd message to struct allocated locally */
            msg.reconfig_cmd.p_cfg = &cfg;
        }

        /* parse message; while we're at it map message sig to event */
        if (msg_type == AVDT_MSG_TYPE_CMD)
        {
            msg.hdr.err_code = err = (*avdt_msg_prs_cmd[sig - 1])(&msg, p, p_buf->len);
            evt = avdt_msg_cmd_2_evt[sig - 1];
        }
        else if (msg_type == AVDT_MSG_TYPE_RSP)
        {
            msg.hdr.err_code = err = (*avdt_msg_prs_rsp[sig - 1])(&msg, p, p_buf->len);
            evt = avdt_msg_rsp_2_evt[sig - 1];
        }
        else /* msg_type == AVDT_MSG_TYPE_REJ */
        {
            err = avdt_msg_prs_rej(&msg, p, sig);
            evt = avdt_msg_rej_2_evt[sig - 1];
        }

        /* if parsing failed */
        if (err != 0)
        {
            AVDT_TRACE_WARNING2("Parsing failed sig=%d err=0x%x", sig, err);

            /* if its a rsp or rej, drop it; if its a cmd, send a rej;
            ** note special case for abort; never send abort reject
            */
            ok = FALSE;
            if ((msg_type == AVDT_MSG_TYPE_CMD) && (sig != AVDT_SIG_ABORT))
            {
                avdt_msg_send_rej(p_ccb, sig, &msg);
            }
        }
    }

    /* if its a rsp or rej, check sent cmd to see if we're waiting for
    ** the rsp or rej.  If we didn't send a cmd for it, drop it.  If
    ** it does match a cmd, stop timer for the cmd.
    */
    if (ok)
    {
        if ((msg_type == AVDT_MSG_TYPE_RSP) || (msg_type == AVDT_MSG_TYPE_REJ))
        {
            if ((p_ccb->p_curr_cmd != NULL) &&
                (p_ccb->p_curr_cmd->event == sig) &&
                (AVDT_LAYERSPEC_LABEL(p_ccb->p_curr_cmd->layer_specific) == label))
            {
                /* stop timer */
                btu_stop_timer(&p_ccb->timer_entry);

                /* clear retransmission count */
                p_ccb->ret_count = 0;

                /* later in this function handle ccb event */
                handle_rsp = TRUE;
            }
            else
            {
                ok = FALSE;
                AVDT_TRACE_WARNING2("Cmd not found for rsp sig=%d label=%d", sig, label);
            }
        }
    }

    if (ok)
    {
        /* if it's a ccb event send to ccb */
        if (evt & AVDT_CCB_MKR)
        {
            avdt_ccb_event(p_ccb, (UINT8)(evt & ~AVDT_CCB_MKR), (tAVDT_CCB_EVT *) &msg);
        }
        /* if it's a scb event */
        else
        {
            /* Scb events always have a single seid.  For cmd, get seid from
            ** message.  For rej and rsp, get seid from p_curr_cmd.
            */
            if (msg_type == AVDT_MSG_TYPE_CMD)
            {
                scb_hdl = msg.single.seid;
            }
            else
            {
                scb_hdl = *((UINT8 *)(p_ccb->p_curr_cmd + 1));
            }

            /* Map seid to the scb and send it the event.  For cmd, seid has
            ** already been verified by parsing function.
            */
            if (evt && (p_scb = avdt_scb_by_hdl(scb_hdl)) != NULL)
            {
                avdt_scb_event(p_scb, evt, (tAVDT_SCB_EVT *) &msg);
            }
        }
    }

    /* free message buffer */
    GKI_freebuf(p_buf);

    /* if its a rsp or rej, send event to ccb to free associated
    ** cmd msg buffer and handle cmd queue
    */
    if (handle_rsp)
    {
        avdt_ccb_event(p_ccb, AVDT_CCB_RCVRSP_EVT, NULL);
    }
}