/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you 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.
 */

/**
 * L2CAP Signaling (channel ID = 5).
 *
 * Design overview:
 *
 * L2CAP sig procedures are initiated by the application via function calls.
 * Such functions return when either of the following happens:
 *
 * (1) The procedure completes (success or failure).
 * (2) The procedure cannot proceed until a BLE peer responds.
 *
 * For (1), the result of the procedure if fully indicated by the function
 * return code.
 * For (2), the procedure result is indicated by an application-configured
 * callback.  The callback is executed when the procedure completes.
 *
 * Notes on thread-safety:
 * 1. The ble_hs mutex must never be locked when an application callback is
 *    executed.  A callback is free to initiate additional host procedures.
 * 2. The only resource protected by the mutex is the list of active procedures
 *    (ble_l2cap_sig_procs).  Thread-safety is achieved by locking the mutex
 *    during removal and insertion operations.  Procedure objects are only
 *    modified while they are not in the list.
 */

#include <string.h>
#include <errno.h>
#include "nimble/ble.h"
#include "ble_hs_priv.h"

#if NIMBLE_BLE_CONNECT
/*****************************************************************************
 * $definitions / declarations                                               *
 *****************************************************************************/

#define BLE_L2CAP_SIG_UNRESPONSIVE_TIMEOUT      30000   /* Milliseconds. */

#define BLE_L2CAP_SIG_PROC_OP_UPDATE            0
#define BLE_L2CAP_SIG_PROC_OP_CONNECT           1
#define BLE_L2CAP_SIG_PROC_OP_RECONFIG          2
#define BLE_L2CAP_SIG_PROC_OP_DISCONNECT        3
#define BLE_L2CAP_SIG_PROC_OP_MAX               4

#if MYNEWT_VAL(BLE_L2CAP_ENHANCED_COC)
#define BLE_L2CAP_ECOC_MIN_MTU  (64)

#define BLE_L2CAP_MAX_COC_CONN_REQ  (5)
#else
#define BLE_L2CAP_MAX_COC_CONN_REQ  (1)
#endif

struct ble_l2cap_sig_proc {
    STAILQ_ENTRY(ble_l2cap_sig_proc) next;

    ble_npl_time_t exp_os_ticks;
    uint16_t conn_handle;
    uint8_t op;
    uint8_t id;

    union {
        struct {
            ble_l2cap_sig_update_fn *cb;
            void *cb_arg;
        } update;
        struct {
            uint8_t chan_cnt;
            struct ble_l2cap_chan *chan[BLE_L2CAP_MAX_COC_CONN_REQ];
        } connect;
        struct {
            struct ble_l2cap_chan *chan;
        } disconnect;
#if MYNEWT_VAL(BLE_L2CAP_ENHANCED_COC)
        struct {
            uint8_t cid_cnt;
            uint16_t cids[BLE_L2CAP_MAX_COC_CONN_REQ];
            uint16_t new_mps;
            uint16_t new_mtu;
        } reconfig;
#endif
    };
};

STAILQ_HEAD(ble_l2cap_sig_proc_list, ble_l2cap_sig_proc);

static struct ble_l2cap_sig_proc_list ble_l2cap_sig_procs;

typedef int ble_l2cap_sig_rx_fn(uint16_t conn_handle,
                                struct ble_l2cap_sig_hdr *hdr,
                                struct os_mbuf **om);

static ble_l2cap_sig_rx_fn ble_l2cap_sig_rx_noop;
static ble_l2cap_sig_rx_fn ble_l2cap_sig_update_req_rx;
static ble_l2cap_sig_rx_fn ble_l2cap_sig_update_rsp_rx;
static ble_l2cap_sig_rx_fn ble_l2cap_sig_rx_reject;

#if MYNEWT_VAL(BLE_L2CAP_COC_MAX_NUM) != 0
static ble_l2cap_sig_rx_fn ble_l2cap_sig_coc_req_rx;
static ble_l2cap_sig_rx_fn ble_l2cap_sig_coc_rsp_rx;
static ble_l2cap_sig_rx_fn ble_l2cap_sig_disc_rsp_rx;
static ble_l2cap_sig_rx_fn ble_l2cap_sig_disc_req_rx;
static ble_l2cap_sig_rx_fn ble_l2cap_sig_le_credits_rx;
#else
#define ble_l2cap_sig_coc_req_rx    ble_l2cap_sig_rx_noop
#define ble_l2cap_sig_coc_rsp_rx    ble_l2cap_sig_rx_noop
#define ble_l2cap_sig_disc_rsp_rx   ble_l2cap_sig_rx_noop
#define ble_l2cap_sig_disc_req_rx   ble_l2cap_sig_rx_noop
#define ble_l2cap_sig_le_credits_rx                  ble_l2cap_sig_rx_noop
#endif

#if MYNEWT_VAL(BLE_L2CAP_ENHANCED_COC)
static ble_l2cap_sig_rx_fn ble_l2cap_sig_credit_base_con_req_rx;
static ble_l2cap_sig_rx_fn ble_l2cap_sig_credit_base_con_rsp_rx;
static ble_l2cap_sig_rx_fn ble_l2cap_sig_credit_base_reconfig_req_rx;
static ble_l2cap_sig_rx_fn ble_l2cap_sig_credit_base_reconfig_rsp_rx;
#else
#define ble_l2cap_sig_credit_base_con_req_rx      ble_l2cap_sig_rx_noop
#define ble_l2cap_sig_credit_base_con_rsp_rx      ble_l2cap_sig_rx_noop
#define ble_l2cap_sig_credit_base_reconfig_req_rx ble_l2cap_sig_rx_noop
#define ble_l2cap_sig_credit_base_reconfig_rsp_rx ble_l2cap_sig_rx_noop
#endif

static ble_l2cap_sig_rx_fn * const ble_l2cap_sig_dispatch[] = {
    [BLE_L2CAP_SIG_OP_REJECT]               = ble_l2cap_sig_rx_reject,
    [BLE_L2CAP_SIG_OP_CONNECT_RSP]          = ble_l2cap_sig_rx_noop,
    [BLE_L2CAP_SIG_OP_CONFIG_RSP]           = ble_l2cap_sig_rx_noop,
    [BLE_L2CAP_SIG_OP_DISCONN_REQ]          = ble_l2cap_sig_disc_req_rx,
    [BLE_L2CAP_SIG_OP_DISCONN_RSP]          = ble_l2cap_sig_disc_rsp_rx,
    [BLE_L2CAP_SIG_OP_ECHO_RSP]             = ble_l2cap_sig_rx_noop,
    [BLE_L2CAP_SIG_OP_INFO_RSP]             = ble_l2cap_sig_rx_noop,
    [BLE_L2CAP_SIG_OP_CREATE_CHAN_RSP]      = ble_l2cap_sig_rx_noop,
    [BLE_L2CAP_SIG_OP_MOVE_CHAN_RSP]        = ble_l2cap_sig_rx_noop,
    [BLE_L2CAP_SIG_OP_MOVE_CHAN_CONF_RSP]   = ble_l2cap_sig_rx_noop,
    [BLE_L2CAP_SIG_OP_UPDATE_REQ]           = ble_l2cap_sig_update_req_rx,
    [BLE_L2CAP_SIG_OP_UPDATE_RSP]           = ble_l2cap_sig_update_rsp_rx,
    [BLE_L2CAP_SIG_OP_LE_CREDIT_CONNECT_REQ]   = ble_l2cap_sig_coc_req_rx,
    [BLE_L2CAP_SIG_OP_LE_CREDIT_CONNECT_RSP]   = ble_l2cap_sig_coc_rsp_rx,
    [BLE_L2CAP_SIG_OP_FLOW_CTRL_CREDIT]     = ble_l2cap_sig_le_credits_rx,
    [BLE_L2CAP_SIG_OP_CREDIT_CONNECT_REQ]   = ble_l2cap_sig_credit_base_con_req_rx,
    [BLE_L2CAP_SIG_OP_CREDIT_CONNECT_RSP]   = ble_l2cap_sig_credit_base_con_rsp_rx,
    [BLE_L2CAP_SIG_OP_CREDIT_RECONFIG_REQ]  = ble_l2cap_sig_credit_base_reconfig_req_rx,
    [BLE_L2CAP_SIG_OP_CREDIT_RECONFIG_RSP]  = ble_l2cap_sig_credit_base_reconfig_rsp_rx,
};

static uint8_t ble_l2cap_sig_cur_id;

static os_membuf_t ble_l2cap_sig_proc_mem[
    OS_MEMPOOL_SIZE(MYNEWT_VAL(BLE_L2CAP_SIG_MAX_PROCS),
                    sizeof (struct ble_l2cap_sig_proc))
];

static struct os_mempool ble_l2cap_sig_proc_pool;

/*****************************************************************************
 * $debug                                                                    *
 *****************************************************************************/

static void
ble_l2cap_sig_dbg_assert_proc_not_inserted(struct ble_l2cap_sig_proc *proc)
{
#if MYNEWT_VAL(BLE_HS_DEBUG)
    struct ble_l2cap_sig_proc *cur;

    STAILQ_FOREACH(cur, &ble_l2cap_sig_procs, next) {
        BLE_HS_DBG_ASSERT(cur != proc);
    }
#endif
}

/*****************************************************************************
 * $misc                                                                     *
 *****************************************************************************/

static uint8_t
ble_l2cap_sig_next_id(void)
{
    ble_l2cap_sig_cur_id++;
    if (ble_l2cap_sig_cur_id == 0) {
        /* An ID of 0 is illegal. */
        ble_l2cap_sig_cur_id = 1;
    }

    return ble_l2cap_sig_cur_id;
}

static ble_l2cap_sig_rx_fn *
ble_l2cap_sig_dispatch_get(uint8_t op)
{
    if (op >= BLE_L2CAP_SIG_OP_MAX) {
        return NULL;
    }

    return ble_l2cap_sig_dispatch[op];
}

/**
 * Allocates a proc entry.
 *
 * @return                      An entry on success; null on failure.
 */
static struct ble_l2cap_sig_proc *
ble_l2cap_sig_proc_alloc(void)
{
    struct ble_l2cap_sig_proc *proc;

    proc = os_memblock_get(&ble_l2cap_sig_proc_pool);
    if (proc != NULL) {
        memset(proc, 0, sizeof *proc);
    }

    return proc;
}

/**
 * Frees the specified proc entry.  No-op if passed a null pointer.
 */
static void
ble_l2cap_sig_proc_free(struct ble_l2cap_sig_proc *proc)
{
    int rc;

    if (proc != NULL) {
        ble_l2cap_sig_dbg_assert_proc_not_inserted(proc);

#if MYNEWT_VAL(BLE_HS_DEBUG)
        memset(proc, 0xff, sizeof *proc);
#endif
        rc = os_memblock_put(&ble_l2cap_sig_proc_pool, proc);
        BLE_HS_DBG_ASSERT_EVAL(rc == 0);
    }
}

/**
 * Tests if a proc entry fits the specified criteria.
 *
 * @param proc                  The procedure to test.
 * @param conn_handle           The connection handle to match against.
 * @param op                    The op code to match against/
 * @param id                    The identifier to match against.
 *                                  0=Ignore this criterion.
 *
 * @return                      1 if the proc matches; 0 otherwise.
 */
static int
ble_l2cap_sig_proc_matches(struct ble_l2cap_sig_proc *proc,
                           uint16_t conn_handle, uint8_t op, uint8_t id)
{
    if (conn_handle != proc->conn_handle) {
        return 0;
    }

    if (op != proc->op) {
        return 0;
    }

    if (id != 0 && id != proc->id) {
        return 0;
    }

    return 1;
}

/**
 * Searches the main proc list for an "expecting" entry whose connection handle
 * and op code match those specified.  If a matching entry is found, it is
 * removed from the list and returned.
 *
 * @param conn_handle           The connection handle to match against.
 * @param op                    The op code to match against.
 * @param identifier            The identifier to match against;
 *                                  0=ignore this criterion.
 *
 * @return                      The matching proc entry on success;
 *                                  null on failure.
 */
static struct ble_l2cap_sig_proc *
ble_l2cap_sig_proc_extract(uint16_t conn_handle, uint8_t op,
                           uint8_t identifier)
{
    struct ble_l2cap_sig_proc *proc;
    struct ble_l2cap_sig_proc *prev;

    ble_hs_lock();

    prev = NULL;
    STAILQ_FOREACH(proc, &ble_l2cap_sig_procs, next) {
        if (ble_l2cap_sig_proc_matches(proc, conn_handle, op, identifier)) {
            if (prev == NULL) {
                STAILQ_REMOVE_HEAD(&ble_l2cap_sig_procs, next);
            } else {
                STAILQ_REMOVE_AFTER(&ble_l2cap_sig_procs, prev, next);
            }
            break;
        }
        prev = proc;
    }

    ble_hs_unlock();

    return proc;
}

static int
ble_l2cap_sig_rx_noop(uint16_t conn_handle,
                      struct ble_l2cap_sig_hdr *hdr,
                      struct os_mbuf **om)
{
    return BLE_HS_ENOTSUP;
}

static void
ble_l2cap_sig_proc_set_timer(struct ble_l2cap_sig_proc *proc)
{
    proc->exp_os_ticks = ble_npl_time_get() +
                         ble_npl_time_ms_to_ticks32(BLE_L2CAP_SIG_UNRESPONSIVE_TIMEOUT);
    ble_hs_timer_resched();
}

static void
ble_l2cap_sig_proc_insert(struct ble_l2cap_sig_proc *proc)
{
    BLE_HS_DBG_ASSERT(ble_hs_locked_by_cur_task());

    ble_l2cap_sig_dbg_assert_proc_not_inserted(proc);

    STAILQ_INSERT_HEAD(&ble_l2cap_sig_procs, proc, next);
}

static void
ble_l2cap_sig_proc_start(struct ble_l2cap_sig_proc *proc)
{
    ble_l2cap_sig_proc_set_timer(proc);
    ble_l2cap_sig_proc_insert(proc);
}

/*****************************************************************************
 * $update                                                                   *
 *****************************************************************************/

static void
ble_l2cap_sig_update_call_cb(struct ble_l2cap_sig_proc *proc, int status)
{
    BLE_HS_DBG_ASSERT(!ble_hs_locked_by_cur_task());

    if (status != 0) {
        STATS_INC(ble_l2cap_stats, update_fail);
    }

    if (proc->update.cb != NULL) {
        proc->update.cb(proc->conn_handle, status, proc->update.cb_arg);
    }
}

static int
ble_l2cap_sig_check_conn_params(const struct ble_gap_upd_params *params)
{
    /* Check connection interval min */
    if ((params->itvl_min < BLE_HCI_CONN_ITVL_MIN) ||
        (params->itvl_min > BLE_HCI_CONN_ITVL_MAX)) {
        return BLE_ERR_INV_HCI_CMD_PARMS;
    }
    /* Check connection interval max */
    if ((params->itvl_max < BLE_HCI_CONN_ITVL_MIN) ||
        (params->itvl_max > BLE_HCI_CONN_ITVL_MAX) ||
        (params->itvl_max < params->itvl_min)) {
        return BLE_ERR_INV_HCI_CMD_PARMS;
    }

    /* Check connection latency */
    if (params->latency > BLE_HCI_CONN_LATENCY_MAX) {
        return BLE_ERR_INV_HCI_CMD_PARMS;
    }

    /* Check supervision timeout */
    if ((params->supervision_timeout < BLE_HCI_CONN_SPVN_TIMEOUT_MIN) ||
        (params->supervision_timeout > BLE_HCI_CONN_SPVN_TIMEOUT_MAX)) {
        return BLE_ERR_INV_HCI_CMD_PARMS;
    }

    /* Check connection event length */
    if (params->min_ce_len > params->max_ce_len) {
        return BLE_ERR_INV_HCI_CMD_PARMS;
    }

    return 0;
}

/* This helper does validation of sizes and (if requested) CIDs sizes */
static int
ble_l2cap_sig_mbuf_pullup_base(struct os_mbuf **om, int base_len, unsigned int *cids_count)
{
    if (cids_count) {
        if (OS_MBUF_PKTLEN(*om) < base_len) {
            return BLE_HS_EBADDATA;
        }

        if ((OS_MBUF_PKTLEN(*om) - base_len) % sizeof(uint16_t)) {
            return BLE_HS_EBADDATA;
        }

        *cids_count = (OS_MBUF_PKTLEN(*om) - base_len) / sizeof(uint16_t);
        if (*cids_count == 0 || *cids_count > BLE_L2CAP_MAX_COC_CONN_REQ) {
            return BLE_HS_EBADDATA;
        }
    } else {
        if (OS_MBUF_PKTLEN(*om) != base_len) {
            return BLE_HS_EBADDATA;
        }
    }

    /* data sizes validated, just pullup all */
    *om = os_mbuf_pullup(*om, OS_MBUF_PKTLEN(*om));
    if (*om == NULL) {
        return BLE_HS_ENOMEM;
    }

    return 0;
}

int
ble_l2cap_sig_update_req_rx(uint16_t conn_handle,
                            struct ble_l2cap_sig_hdr *hdr,
                            struct os_mbuf **om)
{
    struct ble_l2cap_sig_update_req *req;
    struct os_mbuf *txom;
    struct ble_l2cap_sig_update_rsp *rsp;
    struct ble_gap_upd_params params;
    ble_hs_conn_flags_t conn_flags;
    uint16_t l2cap_result;
    int sig_err;
    int rc;

    l2cap_result = 0; /* Silence spurious gcc warning. */

    rc = ble_l2cap_sig_mbuf_pullup_base(om, sizeof(*req), NULL);
    if (rc != 0) {
        return rc;
    }

    rc = ble_hs_atomic_conn_flags(conn_handle, &conn_flags);
    if (rc != 0) {
        return rc;
    }

    /* Only a master can process an update request. */
    sig_err = !(conn_flags & BLE_HS_CONN_F_MASTER);
    if (sig_err) {
        return BLE_HS_EREJECT;
    }

    req = (struct ble_l2cap_sig_update_req *)(*om)->om_data;

    params.itvl_min = le16toh(req->itvl_min);
    params.itvl_max = le16toh(req->itvl_max);
    params.latency = le16toh(req->slave_latency);
    params.supervision_timeout = le16toh(req->timeout_multiplier);
    params.min_ce_len = BLE_GAP_INITIAL_CONN_MIN_CE_LEN;
    params.max_ce_len = BLE_GAP_INITIAL_CONN_MAX_CE_LEN;

    rc = ble_l2cap_sig_check_conn_params(&params);
    if (rc != 0) {
        /* Invalid parameters */
        goto result;
    }

    /* Ask application if slave's connection parameters are acceptable. */
    rc = ble_gap_rx_l2cap_update_req(conn_handle, &params);
    if (rc == 0) {
        /* Application agrees to accept parameters; schedule update. */
        rc = ble_gap_update_params(conn_handle, &params);
    }

result:
    if (rc == 0) {
        l2cap_result = BLE_L2CAP_SIG_UPDATE_RSP_RESULT_ACCEPT;
    } else {
        l2cap_result = BLE_L2CAP_SIG_UPDATE_RSP_RESULT_REJECT;
    }

    rsp = ble_l2cap_sig_cmd_get(BLE_L2CAP_SIG_OP_UPDATE_RSP, hdr->identifier,
                                sizeof(*rsp), &txom);
    if (!rsp) {
        /* No memory for response, lest allow to timeout on remote side */
        return 0;
    }

    rsp->result = htole16(l2cap_result);

    /* Send L2CAP response. */
    ble_l2cap_sig_tx(conn_handle, txom);

    return 0;
}

static int
ble_l2cap_sig_update_rsp_rx(uint16_t conn_handle,
                            struct ble_l2cap_sig_hdr *hdr,
                            struct os_mbuf **om)
{
    struct ble_l2cap_sig_update_rsp *rsp;
    struct ble_l2cap_sig_proc *proc;
    int cb_status;
    int rc;

    proc = ble_l2cap_sig_proc_extract(conn_handle,
                                      BLE_L2CAP_SIG_PROC_OP_UPDATE,
                                      hdr->identifier);
    if (proc == NULL) {
        return 0;
    }

    rc = ble_l2cap_sig_mbuf_pullup_base(om, sizeof(*rsp), NULL);
    if (rc != 0) {
        cb_status = rc;
        goto done;
    }

    rsp = (struct ble_l2cap_sig_update_rsp *)(*om)->om_data;

    switch (le16toh(rsp->result)) {
    case BLE_L2CAP_SIG_UPDATE_RSP_RESULT_ACCEPT:
        cb_status = 0;
        rc = 0;
        break;

    case BLE_L2CAP_SIG_UPDATE_RSP_RESULT_REJECT:
        cb_status = BLE_HS_EREJECT;
        rc = 0;
        break;

    default:
        cb_status = BLE_HS_EBADDATA;
        rc = 0;
        break;
    }

done:
    ble_l2cap_sig_update_call_cb(proc, cb_status);
    ble_l2cap_sig_proc_free(proc);
    return rc;
}

int
ble_l2cap_sig_update_nolock(uint16_t conn_handle,
                            struct ble_l2cap_sig_update_params *params,
                            ble_l2cap_sig_update_fn *cb, void *cb_arg)
{
    struct os_mbuf *txom;
    struct ble_l2cap_sig_update_req *req;
    struct ble_l2cap_sig_proc *proc;
    struct ble_l2cap_chan *chan;
    struct ble_hs_conn *conn;
    int master;
    int rc;

    proc = NULL;

    STATS_INC(ble_l2cap_stats, update_init);

    rc = ble_hs_misc_conn_chan_find_reqd(conn_handle, BLE_L2CAP_CID_SIG,
                                         &conn, &chan);
    if (rc != 0) {
        return rc;
    }

    master = conn->bhc_flags & BLE_HS_CONN_F_MASTER;

    if (master) {
        /* Only the slave can initiate the L2CAP connection update
         * procedure.
         */
        return BLE_HS_EINVAL;
    }

    proc = ble_l2cap_sig_proc_alloc();
    if (proc == NULL) {
        STATS_INC(ble_l2cap_stats, update_fail);
        return BLE_HS_ENOMEM;
    }

    proc->op = BLE_L2CAP_SIG_PROC_OP_UPDATE;
    proc->id = ble_l2cap_sig_next_id();
    proc->conn_handle = conn_handle;
    proc->update.cb = cb;
    proc->update.cb_arg = cb_arg;

    req = ble_l2cap_sig_cmd_get(BLE_L2CAP_SIG_OP_UPDATE_REQ, proc->id,
                                sizeof(*req), &txom);
    if (!req) {
        STATS_INC(ble_l2cap_stats, update_fail);
        ble_l2cap_sig_proc_free(proc);
        return BLE_HS_ENOMEM;
    }

    req->itvl_min = htole16(params->itvl_min);
    req->itvl_max = htole16(params->itvl_max);
    req->slave_latency = htole16(params->slave_latency);
    req->timeout_multiplier = htole16(params->timeout_multiplier);

    rc = ble_l2cap_sig_tx_nolock(conn_handle, txom);
    if (rc) {
        STATS_INC(ble_l2cap_stats, update_fail);
        ble_l2cap_sig_proc_free(proc);
        return rc;
    }

    ble_l2cap_sig_proc_start(proc);
    return 0;
}

int
ble_l2cap_sig_update(uint16_t conn_handle, struct ble_l2cap_sig_update_params *params,
                     ble_l2cap_sig_update_fn *cb, void *cb_arg)
{
    int rc;

    ble_hs_lock();
    rc = ble_l2cap_sig_update_nolock(conn_handle, params, cb, cb_arg);
    ble_hs_unlock();

    return rc;
}

/*****************************************************************************
 * $connect                                                                  *
 *****************************************************************************/

#if MYNEWT_VAL(BLE_L2CAP_COC_MAX_NUM) != 0

static int
ble_l2cap_sig_coc_err2ble_hs_err(uint16_t l2cap_coc_err)
{
    switch (l2cap_coc_err) {
    case BLE_L2CAP_COC_ERR_CONNECTION_SUCCESS:
        return 0;
    case BLE_L2CAP_COC_ERR_UNKNOWN_LE_PSM:
        return BLE_HS_ENOTSUP;
    case BLE_L2CAP_COC_ERR_NO_RESOURCES:
        return BLE_HS_ENOMEM;
    case BLE_L2CAP_COC_ERR_INSUFFICIENT_AUTHEN:
        return BLE_HS_EAUTHEN;
    case BLE_L2CAP_COC_ERR_INSUFFICIENT_AUTHOR:
        return BLE_HS_EAUTHOR;
    case BLE_L2CAP_COC_ERR_INSUFFICIENT_KEY_SZ:
        return BLE_HS_EENCRYPT_KEY_SZ;
    case BLE_L2CAP_COC_ERR_INSUFFICIENT_ENC:
        return BLE_HS_EENCRYPT;
    case BLE_L2CAP_COC_ERR_INVALID_SOURCE_CID:
        return BLE_HS_EREJECT;
    case BLE_L2CAP_COC_ERR_SOURCE_CID_ALREADY_USED:
        return BLE_HS_EALREADY;
    case BLE_L2CAP_COC_ERR_UNACCEPTABLE_PARAMETERS:
        return BLE_HS_EINVAL;
    default:
        return BLE_HS_EUNKNOWN;
    }
}

static int
ble_l2cap_sig_ble_hs_err2coc_err(uint16_t ble_hs_err)
{
    switch (ble_hs_err) {
    case BLE_HS_ENOTSUP:
        return BLE_L2CAP_COC_ERR_UNKNOWN_LE_PSM;
    case BLE_HS_ENOMEM:
        return BLE_L2CAP_COC_ERR_NO_RESOURCES;
    case BLE_HS_EAUTHEN:
        return BLE_L2CAP_COC_ERR_INSUFFICIENT_AUTHEN;
    case BLE_HS_EAUTHOR:
        return BLE_L2CAP_COC_ERR_INSUFFICIENT_AUTHOR;
    case BLE_HS_EENCRYPT:
        return BLE_L2CAP_COC_ERR_INSUFFICIENT_ENC;
    case BLE_HS_EENCRYPT_KEY_SZ:
        return BLE_L2CAP_COC_ERR_INSUFFICIENT_KEY_SZ;
    case BLE_HS_EINVAL:
        return BLE_L2CAP_COC_ERR_UNACCEPTABLE_PARAMETERS;
    default:
        return BLE_L2CAP_COC_ERR_NO_RESOURCES;
    }
}

static void
ble_l2cap_event_coc_connected(struct ble_l2cap_chan *chan, uint16_t status)
{
    struct ble_l2cap_event event = { };

    event.type = BLE_L2CAP_EVENT_COC_CONNECTED;
    event.connect.conn_handle = chan->conn_handle;
    event.connect.chan = chan;
    event.connect.status = status;

    chan->cb(&event, chan->cb_arg);
}

static int
ble_l2cap_event_coc_accept(struct ble_l2cap_chan *chan, uint16_t peer_sdu_size)
{
    struct ble_l2cap_event event = { };

    event.type = BLE_L2CAP_EVENT_COC_ACCEPT;
    event.accept.chan = chan;
    event.accept.conn_handle = chan->conn_handle;
    event.accept.peer_sdu_size = peer_sdu_size;

    return chan->cb(&event, chan->cb_arg);
}

static void
ble_l2cap_sig_coc_connect_cb(struct ble_l2cap_sig_proc *proc, int status)
{
    struct ble_hs_conn *conn;
    struct ble_l2cap_chan *chan;
    int i;
    bool some_not_connected = false;

    if (!proc) {
            return;
    }

    for (i = 0; i < proc->connect.chan_cnt; i++) {
        chan = proc->connect.chan[i];
        if (!chan || !chan->cb) {
            continue;
        }

        if (chan->dcid != 0) {
            ble_l2cap_event_coc_connected(chan, 0);
            /* Let's forget about connected channel now.
             * Not connected will be freed later on.
             */
            proc->connect.chan[i] = NULL;
            continue;
        }
        some_not_connected = true;
        ble_l2cap_event_coc_connected(chan, status ? status : BLE_HS_EREJECT);
    }

    if (!some_not_connected) {
        return;
    }

    /* Free not connected channels*/

    ble_hs_lock();
    conn = ble_hs_conn_find(chan->conn_handle);
    for (i = 0; i < proc->connect.chan_cnt; i++) {
        chan = proc->connect.chan[i];
        if (chan) {
            /* Normally in channel free we send disconnected event to application.
             * However in case on error during creation connection we send connected
             * event with error status. To avoid additional disconnected event lets
             * clear callbacks since we don't needed it anymore.
             */
            chan->cb = NULL;
            ble_l2cap_chan_free(conn, chan);
        }
    }
    ble_hs_unlock();
}

#if MYNEWT_VAL(BLE_L2CAP_ENHANCED_COC)
static void
ble_l2cap_event_coc_reconfigured(uint16_t conn_handle, uint16_t status,
                                 struct ble_l2cap_chan *chan, bool peer)
{
    struct ble_l2cap_event event = { };

    if (peer) {
        event.type = BLE_L2CAP_EVENT_COC_PEER_RECONFIGURED;
    } else {
        event.type = BLE_L2CAP_EVENT_COC_RECONFIG_COMPLETED;
    }
    event.reconfigured.conn_handle = conn_handle;
    event.reconfigured.chan = chan;
    event.reconfigured.status = status;

    chan->cb(&event, chan->cb_arg);
}

static int
ble_l2cap_sig_credit_base_reconfig_req_rx(uint16_t conn_handle,
                                     struct ble_l2cap_sig_hdr *hdr,
                                     struct os_mbuf **om)
{
    struct ble_l2cap_chan *chan[BLE_L2CAP_MAX_COC_CONN_REQ] = {0};
    struct ble_l2cap_sig_credit_base_reconfig_req *req;
    struct ble_l2cap_sig_credit_base_reconfig_rsp *rsp;
    struct ble_hs_conn *conn;
    struct os_mbuf *txom;
    unsigned int i;
    int rc;
    unsigned int cid_cnt;
    uint8_t reduction_mps = 0;

    rc = ble_l2cap_sig_mbuf_pullup_base(om, sizeof(*req), &cid_cnt);
    if (rc != 0) {
        return rc;
    }

    ble_hs_lock();
    conn = ble_hs_conn_find(conn_handle);
    if (!conn) {
        ble_hs_unlock();
        return 0;
    }

    rsp = ble_l2cap_sig_cmd_get(BLE_L2CAP_SIG_OP_CREDIT_RECONFIG_RSP,
                                    hdr->identifier, sizeof(*rsp) , &txom);
    if (!rsp) {
        /* TODO: Reuse request buffer for the response. For now in such a case
         * remote will timeout.
         */
        BLE_HS_LOG(ERROR, "No memory for the response\n");
        ble_hs_unlock();
        return 0;
    }

    req = (struct ble_l2cap_sig_credit_base_reconfig_req *)(*om)->om_data;

    if ((req->mps < BLE_L2CAP_ECOC_MIN_MTU) || (req->mtu < BLE_L2CAP_ECOC_MIN_MTU)) {
        rsp->result = htole16(BLE_L2CAP_ERR_RECONFIG_UNACCEPTED_PARAM);
        goto failed;
    }

    /* Assume request will succeed. If not, result will be updated */
    rsp->result = htole16(BLE_L2CAP_ERR_RECONFIG_SUCCEED);

    for (i = 0; i < cid_cnt; i++) {
        chan[i] = ble_hs_conn_chan_find_by_dcid(conn, req->dcids[i]);
        if (!chan[i]) {
             rsp->result = htole16(BLE_L2CAP_ERR_RECONFIG_INVALID_DCID);
             goto failed;
        }

        if (chan[i]->peer_coc_mps > req->mps) {
            reduction_mps++;
        }

        if (chan[i]->coc_tx.mtu > req->mtu) {
            rsp->result = htole16(BLE_L2CAP_ERR_RECONFIG_REDUCTION_MTU_NOT_ALLOWED);
            goto failed;
        }
    }

    if (reduction_mps > 0 && cid_cnt > 1) {
        rsp->result = htole16(BLE_L2CAP_ERR_RECONFIG_REDUCTION_MPS_NOT_ALLOWED);
        goto failed;
    }

    ble_l2cap_sig_tx_nolock(conn_handle, txom);

    ble_hs_unlock();

    for (i = 0; i < cid_cnt; i++) {
        chan[i]->coc_tx.mtu = req->mtu;
        chan[i]->peer_coc_mps = req->mps;
        ble_l2cap_event_coc_reconfigured(conn_handle, 0, chan[i], true);
    }

    return 0;

failed:
    ble_l2cap_sig_tx_nolock(conn_handle, txom);
    ble_hs_unlock();
    return 0;
}

static void
ble_l2cap_sig_coc_reconfig_cb(struct ble_l2cap_sig_proc *proc, int status)
{
    int i;
    struct ble_l2cap_chan *chan[BLE_L2CAP_MAX_COC_CONN_REQ] = {0};
    struct ble_hs_conn *conn;

    ble_hs_lock();

    conn = ble_hs_conn_find(proc->conn_handle);
    if (!conn) {
        ble_hs_unlock();
        return;
    }

    for (i = 0; i< proc->reconfig.cid_cnt; i++) {
        chan[i] = ble_hs_conn_chan_find_by_scid(conn, proc->reconfig.cids[i]);
        if (status == 0) {
            ble_l2cap_coc_set_new_mtu_mps(chan[i], proc->reconfig.new_mtu, proc->reconfig.new_mps);
        }
    }

    ble_hs_unlock();

    for (i = 0; i < proc->reconfig.cid_cnt; i++) {
        ble_l2cap_event_coc_reconfigured(proc->conn_handle, status, chan[i], false);
    }
}

static int
ble_l2cap_sig_credit_base_reconfig_rsp_rx(uint16_t conn_handle,
                                     struct ble_l2cap_sig_hdr *hdr,
                                     struct os_mbuf **om)
{
    struct ble_l2cap_sig_proc *proc;
    struct ble_l2cap_sig_credit_base_reconfig_rsp *rsp;
    int rc;

    proc = ble_l2cap_sig_proc_extract(conn_handle,
                                      BLE_L2CAP_SIG_PROC_OP_RECONFIG,
                                      hdr->identifier);
    if (!proc) {
        return 0;
    }

    rc = ble_l2cap_sig_mbuf_pullup_base(om, sizeof(*rsp), NULL);
    if (rc != 0) {
        return rc;
    }

    rsp = (struct ble_l2cap_sig_credit_base_reconfig_rsp *)(*om)->om_data;
    ble_l2cap_sig_coc_reconfig_cb(proc, (rsp->result > 0) ? BLE_HS_EREJECT : 0);
    ble_l2cap_sig_proc_free(proc);

    return 0;
}

static int
ble_l2cap_sig_credit_base_con_req_rx(uint16_t conn_handle,
                                     struct ble_l2cap_sig_hdr *hdr,
                                     struct os_mbuf **om)
{
    int rc;
    struct ble_l2cap_sig_credit_base_connect_req *req;
    struct os_mbuf *txom;
    struct ble_l2cap_sig_credit_base_connect_rsp *rsp;
    struct ble_l2cap_chan *chans[5] = { 0 };
    struct ble_hs_conn *conn;
    uint16_t scid;
    unsigned int num_of_scids;
    unsigned int len;
    unsigned int i;

    rc = ble_l2cap_sig_mbuf_pullup_base(om, sizeof(*req), &num_of_scids);
    if (rc != 0) {
        return rc;
    }

    len = sizeof(*rsp) + (num_of_scids * sizeof(rsp->dcids[0]));

    rsp = ble_l2cap_sig_cmd_get(BLE_L2CAP_SIG_OP_CREDIT_CONNECT_RSP,
                                hdr->identifier, len , &txom);
    if (!rsp) {
        /* Well, nothing smart we can do if there is no memory for response.
         * Remote will timeout.
         */
        return 0;
    }

    memset(rsp, 0, len);

    if (hdr->length <= sizeof(*req) || num_of_scids > ARRAY_SIZE(chans)) {
        rsp->result = htole16(BLE_L2CAP_COC_ERR_INVALID_PARAMETERS);
        goto failed;
    }

    req = (struct ble_l2cap_sig_credit_base_connect_req *)(*om)->om_data;

    if ((req->mtu < BLE_L2CAP_ECOC_MIN_MTU) || (req->mps < BLE_L2CAP_ECOC_MIN_MTU)) {
        rsp->result = htole16(BLE_L2CAP_COC_ERR_INVALID_PARAMETERS);
        goto failed;
    }

    /* First verify that provided SCIDs are good */
    for (i = 0; i < num_of_scids; i++) {
        scid = le16toh(req->scids[i]);
        if (scid < BLE_L2CAP_COC_CID_START || scid > BLE_L2CAP_COC_CID_END) {
            rsp->result = htole16(BLE_L2CAP_COC_ERR_INVALID_SOURCE_CID);
            goto failed;
        }
    }

    ble_hs_lock();
    /* we should not handle any disconnects in between unlock-lock so this can
     * be asserted
     */
    conn = ble_hs_conn_find_assert(conn_handle);

    /* Note: to simplify implementation stop processing further channels on
     * error
     */

    for (i = 0; i < num_of_scids; i++) {
        scid = le16toh(req->scids[i]);

        /* verify for already used CIDs */
        if (ble_hs_conn_chan_find_by_dcid(conn, scid)) {
            rsp->result = htole16(BLE_L2CAP_COC_ERR_SOURCE_CID_ALREADY_USED);
            continue;
        }

        rc = ble_l2cap_coc_create_srv_chan(conn, le16toh(req->psm), &chans[i]);
        if (rc != 0) {
            if (rc == BLE_HS_ENOTSUP) {
                /* PSM not supported */
                rsp->result = htole16(ble_l2cap_sig_ble_hs_err2coc_err(rc));
                ble_hs_unlock();
                goto failed;
            }

            /* We cannot process more due to limited resources
             * If we limit further due to eg. authorization result will be
             * overwritten later on
             */
            rsp->result = htole16(BLE_L2CAP_COC_ERR_NO_RESOURCES);
            break;
        }

        /* Fill up remote configuration. Note MPS is the L2CAP MTU*/
        chans[i]->dcid = scid;
        chans[i]->peer_coc_mps = le16toh(req->mps);
        chans[i]->coc_tx.credits = le16toh(req->credits);
        chans[i]->coc_tx.mtu = le16toh(req->mtu);

        ble_hs_conn_chan_insert(conn, chans[i]);

        /* We need to set it once as there are same initial parameters for all
         * the channels, regardless if were accepted or not
         */
        if (rsp->mtu == 0) {
            rsp->mtu = htole16(chans[i]->coc_rx.mtu);
            rsp->mps = htole16(chans[i]->my_mtu);
            rsp->credits = htole16(chans[i]->coc_rx.credits);
        }
    }

    /* further process only channels we have resources for */
    num_of_scids = i;

    /* Sending events to the app. Unlock hs */
    ble_hs_unlock();

    for (i = 0; i < num_of_scids; i++) {
        if (chans[i]) {
            rc = ble_l2cap_event_coc_accept(chans[i], le16toh(req->mtu));
            if (rc != 0) {
                chans[i]->cb = NULL;
                rsp->result = htole16(ble_l2cap_sig_ble_hs_err2coc_err(rc));
                continue;
            }

            rsp->dcids[i] = htole16(chans[i]->scid);
        }
    }

    ble_hs_lock();
    conn = ble_hs_conn_find_assert(conn_handle);

    /* removed not accepted channels */
    for (i = 0; i < num_of_scids; i++) {
        if (chans[i] && chans[i]->cb == NULL) {
            ble_hs_conn_delete_chan(conn, chans[i]);
            chans[i] = NULL;
        }
    }

    /* send response */
    rc = ble_l2cap_sig_tx_nolock(conn_handle, txom);
    if (rc != 0) {
        /* cleanup if we failed to send response
         * TODO should we notify app on failure?
         */
        for (i = 0; i < num_of_scids; i++) {
            if (chans[i]) {
                chans[i]->cb = NULL;
                ble_hs_conn_delete_chan(conn, chans[i]);
                chans[i] = NULL;
            }
        }
    }

    ble_hs_unlock();

    /* Notify user about connection status */
    for (i = 0; i < num_of_scids; i++) {
        if (chans[i]) {
            ble_l2cap_event_coc_connected(chans[i], 0);
        }
    }

    return 0;

failed:
    /* dummy values in case of error, just to satisfy PTS */
    rsp->credits = htole16(1);
    rsp->mps = htole16(BLE_L2CAP_ECOC_MIN_MTU);
    rsp->mtu = htole16(BLE_L2CAP_ECOC_MIN_MTU);
    ble_l2cap_sig_tx(conn_handle, txom);
    return 0;
}

static int
ble_l2cap_sig_credit_base_con_rsp_rx(uint16_t conn_handle,
                                     struct ble_l2cap_sig_hdr *hdr,
                                     struct os_mbuf **om)
{
    struct ble_l2cap_sig_proc *proc;
    struct ble_l2cap_sig_credit_base_connect_rsp *rsp;
    struct ble_l2cap_chan *chan;
    struct ble_hs_conn *conn;
    int rc;
    int i;
    uint16_t duplicated_cids[5] = {};
    unsigned int num_of_dcids;

#if !BLE_MONITOR
    BLE_HS_LOG(DEBUG, "L2CAP LE COC connection response received\n");
#endif

    proc = ble_l2cap_sig_proc_extract(conn_handle,
                                      BLE_L2CAP_SIG_PROC_OP_CONNECT,
                                      hdr->identifier);
    if (!proc) {
        return 0;
    }

    rc = ble_l2cap_sig_mbuf_pullup_base(om, sizeof(*rsp), &num_of_dcids);
    if (rc != 0) {
        goto done;
    }

    /* spec doesn't say what to do in that case so just fail */
    if (proc->connect.chan_cnt != num_of_dcids) {
        goto done;
    }

    rsp = (struct ble_l2cap_sig_credit_base_connect_rsp *)(*om)->om_data;

    if (rsp->result) {
        rc = ble_l2cap_sig_coc_err2ble_hs_err(le16toh(rsp->result));
        /* Below results means that some of the channels has not been created
         * and we have to look closer into the response.
         * Any other results means that all the connections has been refused.
         */
        if ((rsp->result != BLE_L2CAP_COC_ERR_NO_RESOURCES) &&
            (rsp->result != BLE_L2CAP_COC_ERR_INVALID_SOURCE_CID) &&
            (rsp->result != BLE_L2CAP_COC_ERR_SOURCE_CID_ALREADY_USED)) {
            goto done;
        }
    }

    ble_hs_lock();
    conn = ble_hs_conn_find(conn_handle);
    assert(conn != NULL);

    for (i = 0; i < proc->connect.chan_cnt; i++) {
        chan = proc->connect.chan[i];
        if (rsp->dcids[i] == 0) {
            /* Channel rejected, dont put it on the list.
             * User will get notified later in that function
             */
            chan->dcid = 0;
            continue;
        }
        if (ble_hs_conn_chan_find_by_dcid(conn, rsp->dcids[i])) {
            duplicated_cids[i] = rsp->dcids[i];
            chan->dcid = 0;
            continue;
        }

        chan->peer_coc_mps = le16toh(rsp->mps);
        chan->dcid = le16toh(rsp->dcids[i]);
        chan->coc_tx.mtu = le16toh(rsp->mtu);
        chan->coc_tx.credits = le16toh(rsp->credits);

        ble_hs_conn_chan_insert(conn, chan);
    }

    for (i = 0; i < ARRAY_SIZE(duplicated_cids); i++) {
        if (duplicated_cids[i] != 0) {
            chan = ble_hs_conn_chan_find_by_dcid(conn, duplicated_cids[i]);
            rc |= ble_l2cap_sig_disconnect_nolock(chan);
        }
    }

    ble_hs_unlock();

done:
    ble_l2cap_sig_coc_connect_cb(proc, rc);
    ble_l2cap_sig_proc_free(proc);

    /* Silently ignore errors as this is response signal */
    return 0;
}
#endif

static int
ble_l2cap_sig_coc_req_rx(uint16_t conn_handle, struct ble_l2cap_sig_hdr *hdr,
                         struct os_mbuf **om)
{
    int rc;
    struct ble_l2cap_sig_le_con_req *req;
    struct os_mbuf *txom;
    struct ble_l2cap_sig_le_con_rsp *rsp;
    struct ble_l2cap_chan *chan = NULL;
    struct ble_hs_conn *conn;
    uint16_t scid;

    rc = ble_l2cap_sig_mbuf_pullup_base(om, sizeof(*req), NULL);
    if (rc != 0) {
        return rc;
    }

    rsp = ble_l2cap_sig_cmd_get(BLE_L2CAP_SIG_OP_LE_CREDIT_CONNECT_RSP,
                                hdr->identifier, sizeof(*rsp), &txom);
    if (!rsp) {
        /* Well, nothing smart we can do if there is no memory for response.
         * Remote will timeout.
         */
        return 0;
    }

    memset(rsp, 0, sizeof(*rsp));

    req = (struct ble_l2cap_sig_le_con_req *)(*om)->om_data;

    ble_hs_lock();
    conn = ble_hs_conn_find_assert(conn_handle);

    /* Verify CID. Note, scid in the request is dcid for out local channel */
    scid = le16toh(req->scid);
    if (scid < BLE_L2CAP_COC_CID_START || scid > BLE_L2CAP_COC_CID_END) {
        rsp->result = htole16(BLE_L2CAP_COC_ERR_INVALID_SOURCE_CID);
        ble_hs_unlock();
        goto failed;
    }

    chan = ble_hs_conn_chan_find_by_dcid(conn, scid);
    if (chan) {
        rsp->result = htole16(BLE_L2CAP_COC_ERR_SOURCE_CID_ALREADY_USED);
        ble_hs_unlock();
        goto failed;
    }

    rc = ble_l2cap_coc_create_srv_chan(conn, le16toh(req->psm), &chan);
    if (rc != 0) {
        uint16_t coc_err = ble_l2cap_sig_ble_hs_err2coc_err(rc);
        rsp->result = htole16(coc_err);
        ble_hs_unlock();
        goto failed;
    }

    /* Fill up remote configuration. Note MPS is the L2CAP MTU*/
    chan->dcid = scid;
    chan->peer_coc_mps = le16toh(req->mps);
    chan->coc_tx.credits = le16toh(req->credits);
    chan->coc_tx.mtu = le16toh(req->mtu);

    ble_hs_conn_chan_insert(conn, chan);
    ble_hs_unlock();

    rc = ble_l2cap_event_coc_accept(chan, le16toh(req->mtu));
    if (rc != 0) {
        uint16_t coc_err = ble_l2cap_sig_ble_hs_err2coc_err(rc);

        /* Make sure we do not send disconnect event when removing channel */
        chan->cb = NULL;

        ble_hs_lock();
        conn = ble_hs_conn_find_assert(conn_handle);
        ble_hs_conn_delete_chan(conn, chan);
        ble_hs_unlock();
        rsp->result = htole16(coc_err);
        goto failed;
    }

    rsp->dcid = htole16(chan->scid);
    rsp->credits = htole16(chan->coc_rx.credits);
    rsp->mps = htole16(chan->my_coc_mps);
    rsp->mtu = htole16(chan->coc_rx.mtu);
    rsp->result = htole16(BLE_L2CAP_COC_ERR_CONNECTION_SUCCESS);

    rc = ble_l2cap_sig_tx(conn_handle, txom);
    if (rc != 0) {
        ble_hs_lock();
        conn = ble_hs_conn_find_assert(conn_handle);
        ble_hs_conn_delete_chan(conn, chan);
        ble_hs_unlock();
        return 0;
    }

    /* Notify user about connection status */
    ble_l2cap_event_coc_connected(chan, rc);

    return 0;

failed:
    ble_l2cap_sig_tx(conn_handle, txom);
    return 0;
}

static int
ble_l2cap_sig_coc_rsp_rx(uint16_t conn_handle, struct ble_l2cap_sig_hdr *hdr,
                          struct os_mbuf **om)
{
    struct ble_l2cap_sig_proc *proc;
    struct ble_l2cap_sig_le_con_rsp *rsp;
    struct ble_l2cap_chan *chan;
    struct ble_hs_conn *conn;
    int rc;

#if !BLE_MONITOR
    BLE_HS_LOG(DEBUG, "L2CAP LE COC connection response received\n");
#endif

    proc = ble_l2cap_sig_proc_extract(conn_handle,
                                      BLE_L2CAP_SIG_PROC_OP_CONNECT,
                                      hdr->identifier);
    if (!proc) {
        return 0;
    }

    rc = ble_l2cap_sig_mbuf_pullup_base(om, sizeof(*rsp), NULL);
    if (rc != 0) {
        goto done;
    }

    rsp = (struct ble_l2cap_sig_le_con_rsp *)(*om)->om_data;

    chan = proc->connect.chan[0];

    if (rsp->result) {
        rc = ble_l2cap_sig_coc_err2ble_hs_err(le16toh(rsp->result));
        goto done;
    }

    /* Fill up remote configuration
     * Note MPS is the L2CAP MTU
     */
    chan->peer_coc_mps = le16toh(rsp->mps);
    chan->dcid = le16toh(rsp->dcid);
    chan->coc_tx.mtu = le16toh(rsp->mtu);
    chan->coc_tx.credits = le16toh(rsp->credits);

    ble_hs_lock();
    conn = ble_hs_conn_find(conn_handle);
    assert(conn != NULL);
    ble_hs_conn_chan_insert(conn, chan);
    ble_hs_unlock();

    rc = 0;

done:
    ble_l2cap_sig_coc_connect_cb(proc, rc);
    ble_l2cap_sig_proc_free(proc);

    /* Silently ignore errors as this is response signal */
    return 0;
}

int
ble_l2cap_sig_connect_nolock(uint16_t conn_handle, uint16_t psm, uint16_t mtu,
                             struct os_mbuf *sdu_rx, ble_l2cap_event_fn *cb,
                             void *cb_arg)
{
    struct ble_hs_conn *conn;
    struct ble_l2cap_sig_proc *proc;
    struct os_mbuf *txom;
    struct ble_l2cap_sig_le_con_req *req;
    struct ble_l2cap_chan *chan = NULL;
    int rc;

    if (!sdu_rx || !cb) {
        return BLE_HS_EINVAL;
    }

    conn = ble_hs_conn_find(conn_handle);
    if (!conn) {
        return BLE_HS_ENOTCONN;
    }

    chan = ble_l2cap_coc_chan_alloc(conn, psm, mtu, sdu_rx, cb, cb_arg);
    if (!chan) {
        return BLE_HS_ENOMEM;
    }

    proc = ble_l2cap_sig_proc_alloc();
    if (!proc) {
        ble_l2cap_chan_free(conn, chan);
        return BLE_HS_ENOMEM;
    }

    proc->op = BLE_L2CAP_SIG_PROC_OP_CONNECT;
    proc->id = ble_l2cap_sig_next_id();
    proc->conn_handle = conn_handle;
    proc->connect.chan[0] = chan;
    proc->connect.chan_cnt = 1;

    req = ble_l2cap_sig_cmd_get(BLE_L2CAP_SIG_OP_LE_CREDIT_CONNECT_REQ, proc->id,
                                sizeof(*req), &txom);
    if (!req) {
        ble_l2cap_chan_free(conn, chan);
        ble_l2cap_sig_proc_free(proc);
        return BLE_HS_ENOMEM;
    }

    req->psm = htole16(psm);
    req->scid = htole16(chan->scid);
    req->mtu = htole16(chan->coc_rx.mtu);
    req->mps = htole16(chan->my_coc_mps);
    req->credits = htole16(chan->coc_rx.credits);

    rc = ble_l2cap_sig_tx_nolock(proc->conn_handle, txom);
    if (rc != 0) {
        ble_l2cap_chan_free(conn, chan);
        ble_l2cap_sig_proc_free(proc);
        return rc;
    }

    ble_l2cap_sig_proc_start(proc);

    return 0;
}

#if MYNEWT_VAL(BLE_L2CAP_ENHANCED_COC)
int
ble_l2cap_sig_ecoc_connect_nolock(uint16_t conn_handle, uint16_t psm, uint16_t mtu,
                                  uint8_t num, struct os_mbuf *sdu_rx[],
                                  ble_l2cap_event_fn *cb, void *cb_arg)
{
    struct ble_hs_conn *conn;
    struct ble_l2cap_sig_proc *proc;
    struct os_mbuf *txom;
    struct ble_l2cap_sig_credit_base_connect_req *req;
    int rc;
    int i;

    if (!sdu_rx || !cb) {
        return BLE_HS_EINVAL;
    }

    conn = ble_hs_conn_find(conn_handle);
    if (!conn) {
        return BLE_HS_ENOTCONN;
    }

    proc = ble_l2cap_sig_proc_alloc();
    if (!proc) {
        return BLE_HS_ENOMEM;
    }

    proc->op = BLE_L2CAP_SIG_PROC_OP_CONNECT;
    proc->id = ble_l2cap_sig_next_id();
    proc->conn_handle = conn_handle;

    req = ble_l2cap_sig_cmd_get(BLE_L2CAP_SIG_OP_CREDIT_CONNECT_REQ, proc->id,
                                sizeof(*req) + num * sizeof(uint16_t), &txom);
    if (!req) {
        ble_l2cap_sig_proc_free(proc);
        return BLE_HS_ENOMEM;
    }

    for (i = 0; i < num; i++) {
        proc->connect.chan[i] =
            ble_l2cap_coc_chan_alloc(conn, psm, mtu, sdu_rx[i], cb, cb_arg);
        if (!proc->connect.chan[i]) {
            /* Clear request buffer */
            os_mbuf_free_chain(txom);
            rc = BLE_HS_ENOMEM;
            goto failed;
        }
    }
    proc->connect.chan_cnt = num;

    /* all channels have same params */
    req->psm = htole16(psm);
    req->mtu = htole16(proc->connect.chan[0]->coc_rx.mtu);
    req->mps = htole16(proc->connect.chan[0]->my_mtu);
    req->credits = htole16(proc->connect.chan[0]->coc_rx.credits);
    for (i = 0; i < num; i++) {
        req->scids[i] = htole16(proc->connect.chan[i]->scid);
    }

    rc = ble_l2cap_sig_tx_nolock(proc->conn_handle, txom);
    if (rc) {
        rc = BLE_HS_ENOMEM;
        goto failed;
    }

    ble_l2cap_sig_proc_start(proc);

    return 0;

failed:
    /* clean up on failure, ble_l2cap_chan_free() handles NULL as well */
    for (i = 0; i < num; i++) {
        proc->connect.chan[i]->cb = NULL;
        ble_l2cap_chan_free(conn, proc->connect.chan[i]);
    }

    ble_l2cap_sig_proc_free(proc);
    return BLE_HS_ENOMEM;
}

int
ble_l2cap_sig_coc_reconfig_nolock(uint16_t conn_handle,
                                  struct ble_l2cap_chan *chans[], uint8_t num,
                                  uint16_t new_mtu)
{
    struct ble_hs_conn *conn;
    struct ble_l2cap_sig_proc *proc;
    struct os_mbuf *txom;
    struct ble_l2cap_sig_credit_base_reconfig_req *req;
    int rc;
    int i;

    conn = ble_hs_conn_find(conn_handle);
    if (!conn) {
        return BLE_HS_ENOTCONN;
    }

    proc = ble_l2cap_sig_proc_alloc();
    if (!proc) {
        return BLE_HS_ENOMEM;
    }

    for (i = 0; i < num; i++) {
        if (ble_hs_conn_chan_exist(conn, chans[i])) {
            proc->reconfig.cids[i] = chans[i]->scid;
        } else {
            ble_l2cap_sig_proc_free(proc);
            return BLE_HS_ENOMEM;
        }
    }

    proc->op = BLE_L2CAP_SIG_PROC_OP_RECONFIG;
    proc->reconfig.cid_cnt = num;
    proc->reconfig.new_mtu = new_mtu;
    proc->reconfig.new_mps = MYNEWT_VAL(BLE_L2CAP_COC_MPS);
    proc->id = ble_l2cap_sig_next_id();
    proc->conn_handle = conn_handle;

    req = ble_l2cap_sig_cmd_get(BLE_L2CAP_SIG_OP_CREDIT_RECONFIG_REQ, proc->id,
                                sizeof(*req) + num * sizeof(uint16_t), &txom);
    if (!req) {
        ble_l2cap_sig_proc_free(proc);
        return BLE_HS_ENOMEM;
    }

    /* For now we allow to change CoC MTU only.*/
    req->mtu = htole16(proc->reconfig.new_mtu);
    req->mps = htole16(proc->reconfig.new_mps);

    for (i = 0; i < num; i++) {
        req->dcids[i] = htole16(proc->reconfig.cids[i]);
    }

    rc = ble_l2cap_sig_tx_nolock(proc->conn_handle, txom);
    if (rc) {
        ble_l2cap_sig_proc_free(proc);
        return rc;
    }

    ble_l2cap_sig_proc_start(proc);
    return 0;
}
#endif

/*****************************************************************************
 * $disconnect                                                               *
 *****************************************************************************/

static int
ble_l2cap_sig_disc_req_rx(uint16_t conn_handle, struct ble_l2cap_sig_hdr *hdr,
                          struct os_mbuf **om)
{
    struct ble_l2cap_sig_disc_req *req;
    struct os_mbuf *txom;
    struct ble_l2cap_sig_disc_rsp *rsp;
    struct ble_l2cap_chan *chan;
    struct ble_hs_conn *conn;
    int rc;
    uint16_t scid;
    uint16_t dcid;

    rc = ble_l2cap_sig_mbuf_pullup_base(om, sizeof(*req), NULL);
    if (rc != 0) {
        return rc;
    }

    rsp = ble_l2cap_sig_cmd_get(BLE_L2CAP_SIG_OP_DISCONN_RSP, hdr->identifier,
                                sizeof(*rsp), &txom);
    if (!rsp) {
        /* Well, nothing smart we can do if there is no memory for response.
         * Remote will timeout.
         */
        return 0;
    }

    ble_hs_lock();
    conn = ble_hs_conn_find_assert(conn_handle);

    req = (struct ble_l2cap_sig_disc_req *) (*om)->om_data;
    scid = le16toh(req->scid);
    dcid = le16toh(req->dcid);

    if (scid < BLE_L2CAP_COC_CID_START || scid > BLE_L2CAP_COC_CID_END ||
        dcid < BLE_L2CAP_COC_CID_START || dcid > BLE_L2CAP_COC_CID_END) {
        /* Don't bother with look-up if it is not for connection oriented
         * channel
         */
        chan = NULL;
    } else {
        /* Let's find matching channel. Note that destination CID in the request
         * is from peer perspective. It is source CID from nimble perspective
         */
        chan = ble_hs_conn_chan_find_by_scid(conn, dcid);
    }

    if (!chan) {
        os_mbuf_free_chain(txom);
        ble_hs_unlock();
        ble_l2cap_sig_reject_invalid_cid_tx(conn_handle, hdr->identifier, req->dcid, req->scid);
        return 0;
    }

    /* Core Spec 6.0 Vol3 PartA 4.6
     * If the receiver finds a DCID match but the SCID fails to find the same
     * match, the request should be silently discarded.
     */
    if (scid != chan->dcid) {
        os_mbuf_free_chain(txom);
        ble_hs_unlock();
        return 0;
    }

    /* Note that in the response destination CID is form peer perspective and
     * it is source CID from nimble perspective.
     */
    rsp->dcid = htole16(chan->scid);
    rsp->scid = htole16(chan->dcid);

    ble_hs_conn_delete_chan(conn, chan);
    ble_hs_unlock();

    ble_l2cap_sig_tx(conn_handle, txom);
    return 0;
}

static void
ble_l2cap_sig_coc_disconnect_cb(struct ble_l2cap_sig_proc *proc, int status)
{
    struct ble_l2cap_chan *chan;
    struct ble_hs_conn *conn;

    assert(proc);

    chan = proc->disconnect.chan;
    if (!chan) {
        return;
    }

    ble_hs_lock();
    conn = ble_hs_conn_find_assert(chan->conn_handle);
    if (conn) {
        ble_hs_conn_delete_chan(conn, chan);
    } else {
        ble_l2cap_chan_free(NULL, chan);
    }
    ble_hs_unlock();
}

static int
ble_l2cap_sig_disc_rsp_rx(uint16_t conn_handle, struct ble_l2cap_sig_hdr *hdr,
                           struct os_mbuf **om)
{
    struct ble_l2cap_sig_disc_rsp *rsp;
    struct ble_l2cap_sig_proc *proc;
    struct ble_l2cap_chan *chan;
    int rc;

    proc = ble_l2cap_sig_proc_extract(conn_handle,
                                      BLE_L2CAP_SIG_PROC_OP_DISCONNECT,
                                      hdr->identifier);
    if (!proc) {
        return 0;
    }

    rc = ble_l2cap_sig_mbuf_pullup_base(om, sizeof(*rsp), NULL);
    if (rc != 0) {
        goto done;
    }

    chan = proc->disconnect.chan;
    if (!chan) {
        goto done;
    }

    rsp = (struct ble_l2cap_sig_disc_rsp *)(*om)->om_data;
    if (chan->dcid != le16toh(rsp->dcid) || chan->scid != le16toh(rsp->scid)) {
        /* This response is incorrect, lets wait for timeout */
        ble_l2cap_sig_proc_start(proc);
        return 0;
    }

    ble_l2cap_sig_coc_disconnect_cb(proc, rc);

done:
    ble_l2cap_sig_proc_free(proc);
    return 0;
}

int
ble_l2cap_sig_disconnect_nolock(struct ble_l2cap_chan *chan)
{
    struct os_mbuf *txom;
    struct ble_l2cap_sig_disc_req *req;
    struct ble_l2cap_sig_proc *proc;
    int rc;

    /* this is allowed only for connection oriented channels */
    if (chan->scid < BLE_L2CAP_COC_CID_START || chan->scid > BLE_L2CAP_COC_CID_END) {
        return BLE_HS_EREJECT;
    }

    if (chan->flags & BLE_L2CAP_CHAN_F_DISCONNECTING) {
        return 0;
    }

    proc = ble_l2cap_sig_proc_alloc();
    if (proc == NULL) {
        return BLE_HS_ENOMEM;
    }

    proc->op = BLE_L2CAP_SIG_PROC_OP_DISCONNECT;
    proc->id = ble_l2cap_sig_next_id();
    proc->conn_handle = chan->conn_handle;
    proc->disconnect.chan = chan;

    req = ble_l2cap_sig_cmd_get(BLE_L2CAP_SIG_OP_DISCONN_REQ, proc->id,
                                sizeof(*req), &txom);
    if (!req) {
        ble_l2cap_sig_proc_free(proc);
        return BLE_HS_ENOMEM;
    }

    req->dcid = htole16(chan->dcid);
    req->scid = htole16(chan->scid);

    rc = ble_l2cap_sig_tx_nolock(proc->conn_handle, txom);
    if (rc) {
        ble_l2cap_sig_proc_free(proc);
        return rc;
    }

    /* Mark channel as disconnecting */
    chan->flags |= BLE_L2CAP_CHAN_F_DISCONNECTING;
    ble_l2cap_sig_proc_start(proc);

    return 0;
}

static int
ble_l2cap_sig_le_credits_rx(uint16_t conn_handle, struct ble_l2cap_sig_hdr *hdr,
                            struct os_mbuf **om)
{
    struct ble_l2cap_sig_le_credits *req;
    int rc;

    rc = ble_l2cap_sig_mbuf_pullup_base(om, sizeof(*req), NULL);
    if (rc != 0) {
        return 0;
    }

    req = (struct ble_l2cap_sig_le_credits *) (*om)->om_data;

    /* Ignore when peer sends zero credits */
    if (req->credits == 0) {
            return 0;
    }

    ble_l2cap_coc_le_credits_update(conn_handle, le16toh(req->scid),
                                    le16toh(req->credits));

    return 0;
}

int
ble_l2cap_sig_le_credits_nolock(uint16_t conn_handle, uint16_t scid, uint16_t credits)
{
    struct ble_l2cap_sig_le_credits *cmd;
    struct os_mbuf *txom;

    cmd = ble_l2cap_sig_cmd_get(BLE_L2CAP_SIG_OP_FLOW_CTRL_CREDIT,
                                ble_l2cap_sig_next_id(), sizeof(*cmd), &txom);

    if (!cmd) {
        return BLE_HS_ENOMEM;
    }

    cmd->scid = htole16(scid);
    cmd->credits = htole16(credits);

    return ble_l2cap_sig_tx_nolock(conn_handle, txom);
}

int
ble_l2cap_sig_le_credits(uint16_t conn_handle, uint16_t scid, uint16_t credits)
{
    int rc;

    ble_hs_lock();
    rc = ble_l2cap_sig_le_credits_nolock(conn_handle, scid, credits);
    ble_hs_unlock();

    return rc;
}
#endif

static int
ble_l2cap_sig_rx_reject(uint16_t conn_handle,
                        struct ble_l2cap_sig_hdr *hdr,
                        struct os_mbuf **om)
{
    struct ble_l2cap_sig_proc *proc;
    proc = ble_l2cap_sig_proc_extract(conn_handle,
                                         BLE_L2CAP_SIG_PROC_OP_CONNECT,
                                         hdr->identifier);
   if (!proc) {
       return 0;
   }

   switch (proc->op) {
#if MYNEWT_VAL(BLE_L2CAP_COC_MAX_NUM) != 0
   case BLE_L2CAP_SIG_PROC_OP_CONNECT:
       ble_l2cap_sig_coc_connect_cb(proc, BLE_HS_EREJECT);
       break;
#endif
   default:
       break;
   }

   ble_l2cap_sig_proc_free(proc);
   return 0;
}
/*****************************************************************************
 * $misc                                                                     *
 *****************************************************************************/

static int
ble_l2cap_sig_rx(struct ble_l2cap_chan *chan, struct os_mbuf **om)
{
    struct ble_l2cap_sig_hdr hdr;
    ble_l2cap_sig_rx_fn *rx_cb;
    uint16_t conn_handle;
    int rc;

    conn_handle = chan->conn_handle;

    STATS_INC(ble_l2cap_stats, sig_rx);

#if !BLE_MONITOR
    BLE_HS_LOG(DEBUG, "L2CAP - rxed signalling msg: ");
    ble_hs_log_mbuf(*om);
    BLE_HS_LOG(DEBUG, "\n");
#endif

    rc = ble_hs_mbuf_pullup_base(om, BLE_L2CAP_SIG_HDR_SZ);
    if (rc != 0) {
        return rc;
    }

    ble_l2cap_sig_hdr_parse((*om)->om_data, (*om)->om_len, &hdr);

    /* Strip L2CAP sig header from the front of the mbuf. */
    os_mbuf_adj(*om, BLE_L2CAP_SIG_HDR_SZ);

    if (OS_MBUF_PKTLEN(*om) != hdr.length) {
        return BLE_HS_EBADDATA;
    }

    rx_cb = ble_l2cap_sig_dispatch_get(hdr.op);
    if (rx_cb == NULL) {
        rc = BLE_HS_EREJECT;
    } else {
        rc = rx_cb(conn_handle, &hdr, om);
    }

    if (rc) {
        ble_l2cap_sig_reject_tx(conn_handle, hdr.identifier,
                                        BLE_L2CAP_SIG_ERR_CMD_NOT_UNDERSTOOD,
                                        NULL, 0);
    }

    return rc;
}

struct ble_l2cap_chan *
ble_l2cap_sig_create_chan(uint16_t conn_handle)
{
    struct ble_l2cap_chan *chan;

    chan = ble_l2cap_chan_alloc(conn_handle);
    if (chan == NULL) {
        return NULL;
    }

    chan->scid = BLE_L2CAP_CID_SIG;
    chan->dcid = BLE_L2CAP_CID_SIG;
    chan->my_mtu = BLE_L2CAP_SIG_MTU;
    chan->rx_fn = ble_l2cap_sig_rx;

    return chan;
}

/**
 * @return                      The number of ticks until the next expiration
 *                                  occurs.
 */
static int32_t
ble_l2cap_sig_extract_expired(struct ble_l2cap_sig_proc_list *dst_list)
{
    struct ble_l2cap_sig_proc *proc;
    struct ble_l2cap_sig_proc *prev;
    struct ble_l2cap_sig_proc *next;
    ble_npl_time_t now;
    ble_npl_stime_t next_exp_in;
    ble_npl_stime_t time_diff;

    now = ble_npl_time_get();
    STAILQ_INIT(dst_list);

    /* Assume each event is either expired or has infinite duration. */
    next_exp_in = BLE_HS_FOREVER;

    ble_hs_lock();

    next = NULL;
    proc = STAILQ_FIRST(&ble_l2cap_sig_procs);
    while (proc != NULL) {
        prev = next;
        next = STAILQ_NEXT(proc, next);

        time_diff = proc->exp_os_ticks - now;
        if (time_diff <= 0) {
            /* Procedure has expired; move it to the destination list. */
            if (prev == NULL) {
                STAILQ_REMOVE_HEAD(&ble_l2cap_sig_procs, next);
            } else {
                STAILQ_REMOVE_AFTER(&ble_l2cap_sig_procs, prev, next);
            }
            STAILQ_INSERT_TAIL(dst_list, proc, next);
        } else {
            if (time_diff < next_exp_in) {
                next_exp_in = time_diff;
            }
        }

        proc = next;
    }

    ble_hs_unlock();

    return next_exp_in;
}

void
ble_l2cap_sig_conn_broken(uint16_t conn_handle, int reason)
{
    struct ble_l2cap_sig_proc *proc;

    /* If there were any pending procedure, indicate to the application that it
     * did not complete.
     */
    proc = ble_l2cap_sig_proc_extract(conn_handle, BLE_L2CAP_SIG_PROC_OP_UPDATE, 0);
    if (proc != NULL) {
        ble_l2cap_sig_update_call_cb(proc, reason);
        ble_l2cap_sig_proc_free(proc);
    }

#if MYNEWT_VAL(BLE_L2CAP_COC_MAX_NUM) != 0
    proc = ble_l2cap_sig_proc_extract(conn_handle, BLE_L2CAP_SIG_PROC_OP_CONNECT, 0);
    if (proc != NULL) {
        ble_l2cap_sig_coc_connect_cb(proc, reason);
        ble_l2cap_sig_proc_free(proc);
    }

    proc = ble_l2cap_sig_proc_extract(conn_handle,
                                      BLE_L2CAP_SIG_PROC_OP_DISCONNECT, 0);
    if (proc != NULL) {
        ble_l2cap_sig_coc_disconnect_cb(proc, reason);
        ble_l2cap_sig_proc_free(proc);
    }

#if MYNEWT_VAL(BLE_L2CAP_ENHANCED_COC)
    proc = ble_l2cap_sig_proc_extract(conn_handle, BLE_L2CAP_SIG_PROC_OP_RECONFIG, 0);
    if (proc != NULL) {
        ble_l2cap_sig_coc_reconfig_cb(proc, reason);
        ble_l2cap_sig_proc_free(proc);
    }
#endif
#endif
}

/**
 * Terminates expired procedures.
 *
 * @return                      The number of ticks until this function should
 *                                  be called again.
 */
int32_t
ble_l2cap_sig_timer(void)
{
    struct ble_l2cap_sig_proc_list temp_list;
    struct ble_l2cap_sig_proc *proc;
    int32_t ticks_until_exp;

    /* Remove timed-out procedures from the main list and insert them into a
     * temporary list.  This function also calculates the number of ticks until
     * the next expiration will occur.
     */
    ticks_until_exp = ble_l2cap_sig_extract_expired(&temp_list);

    /* Report a failure for each timed out procedure. */
    while ((proc = STAILQ_FIRST(&temp_list)) != NULL) {
        STATS_INC(ble_l2cap_stats, proc_timeout);
        switch(proc->op) {
        case BLE_L2CAP_SIG_PROC_OP_UPDATE:
            ble_l2cap_sig_update_call_cb(proc, BLE_HS_ETIMEOUT);
            break;
#if MYNEWT_VAL(BLE_L2CAP_COC_MAX_NUM) != 0
        case BLE_L2CAP_SIG_PROC_OP_CONNECT:
            ble_l2cap_sig_coc_connect_cb(proc, BLE_HS_ETIMEOUT);
            break;
        case BLE_L2CAP_SIG_PROC_OP_DISCONNECT:
            ble_l2cap_sig_coc_disconnect_cb(proc, BLE_HS_ETIMEOUT);
            break;
#endif
        }

        STAILQ_REMOVE_HEAD(&temp_list, next);
        ble_l2cap_sig_proc_free(proc);
    }

    return ticks_until_exp;
}

int
ble_l2cap_sig_init(void)
{
    int rc;

    STAILQ_INIT(&ble_l2cap_sig_procs);

    rc = os_mempool_init(&ble_l2cap_sig_proc_pool,
                         MYNEWT_VAL(BLE_L2CAP_SIG_MAX_PROCS),
                         sizeof (struct ble_l2cap_sig_proc),
                         ble_l2cap_sig_proc_mem,
                         "ble_l2cap_sig_proc_pool");
    if (rc != 0) {
        return rc;
    }

    return 0;
}

#endif
