Archipelago » qemu

/*

 * QEMU Bluetooth L2CAP logic.

 *

 * Copyright (C) 2008 Andrzej Zaborowski  <balrog@zabor.org>

 *

 * This program is free software; you can redistribute it and/or

 * modify it under the terms of the GNU General Public License as

 * published by the Free Software Foundation; either version 2 of

 * the License, or (at your option) any later version.

 *

 * This program is distributed in the hope that it will be useful,

 * but WITHOUT ANY WARRANTY; without even the implied warranty of

 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the

 * GNU General Public License for more details.

 *

 * You should have received a copy of the GNU General Public License

 * along with this program; if not, write to the Free Software

 * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,

 * MA  02110-1301  USA

 */

#include "qemu-common.h"

#include "qemu-timer.h"

#include "bt.h"

#define L2CAP_CID_MAX        0x100        /* Between 0x40 and 0x10000 */

struct l2cap_instance_s {

    struct bt_link_s *link;

    struct bt_l2cap_device_s *dev;

    int role;

    uint8_t frame_in[65535 + L2CAP_HDR_SIZE] __attribute__ ((aligned (4)));

    int frame_in_len;

    uint8_t frame_out[65535 + L2CAP_HDR_SIZE] __attribute__ ((aligned (4)));

    int frame_out_len;

    /* Signalling channel timers.  They exist per-request but we can make

     * sure we have no more than one outstanding request at any time.  */

    QEMUTimer *rtx;

    QEMUTimer *ertx;

    int last_id;

    int next_id;

    struct l2cap_chan_s {

        struct bt_l2cap_conn_params_s params;

        void (*frame_in)(struct l2cap_chan_s *chan, uint16_t cid,

                        const l2cap_hdr *hdr, int len);

        int mps;

        int min_mtu;

        struct l2cap_instance_s *l2cap;

        /* Only allocated channels */

        uint16_t remote_cid;

#define L2CAP_CFG_INIT        2

#define L2CAP_CFG_ACC        1

        int config_req_id; /* TODO: handle outgoing requests generically */

        int config;

        /* Only connection-oriented channels.  Note: if we allow the tx and

         * rx traffic to be in different modes at any time, we need two.  */

        int mode;

        /* Only flow-controlled, connection-oriented channels */

        uint8_t sdu[65536]; /* TODO: dynamically allocate */

        int len_cur, len_total;

        int rexmit;

        int monitor_timeout;

        QEMUTimer *monitor_timer;

        QEMUTimer *retransmission_timer;

    } *cid[L2CAP_CID_MAX];

    /* The channel state machine states map as following:

     * CLOSED           -> !cid[N]

     * WAIT_CONNECT     -> never occurs

     * WAIT_CONNECT_RSP -> never occurs

     * CONFIG           -> cid[N] && config < 3

     *   WAIT_CONFIG         -> never occurs, cid[N] && config == 0 && !config_r

     *   WAIT_SEND_CONFIG    -> never occurs, cid[N] && config == 1 && !config_r

     *   WAIT_CONFIG_REQ_RSP -> cid[N] && config == 0 && config_req_id

     *   WAIT_CONFIG_RSP     -> cid[N] && config == 1 && config_req_id

     *   WAIT_CONFIG_REQ     -> cid[N] && config == 2

     * OPEN             -> cid[N] && config == 3

     * WAIT_DISCONNECT  -> never occurs

     */

    struct l2cap_chan_s signalling_ch;

    struct l2cap_chan_s group_ch;

};

struct slave_l2cap_instance_s {

    struct bt_link_s link;        /* Underlying logical link (ACL) */

    struct l2cap_instance_s l2cap;

};

struct bt_l2cap_psm_s {

    int psm;

    int min_mtu;

    int (*new_channel)(struct bt_l2cap_device_s *device,

                    struct bt_l2cap_conn_params_s *params);

    struct bt_l2cap_psm_s *next;

};

static const uint16_t l2cap_fcs16_table[256] = {

    0x0000, 0xc0c1, 0xc181, 0x0140, 0xc301, 0x03c0, 0x0280, 0xc241,

    0xc601, 0x06c0, 0x0780, 0xc741, 0x0500, 0xc5c1, 0xc481, 0x0440,

    0xcc01, 0x0cc0, 0x0d80, 0xcd41, 0x0f00, 0xcfc1, 0xce81, 0x0e40,

    0x0a00, 0xcac1, 0xcb81, 0x0b40, 0xc901, 0x09c0, 0x0880, 0xc841,

    0xd801, 0x18c0, 0x1980, 0xd941, 0x1b00, 0xdbc1, 0xda81, 0x1a40,

    0x1e00, 0xdec1, 0xdf81, 0x1f40, 0xdd01, 0x1dc0, 0x1c80, 0xdc41,

    0x1400, 0xd4c1, 0xd581, 0x1540, 0xd701, 0x17c0, 0x1680, 0xd641,

    0xd201, 0x12c0, 0x1380, 0xd341, 0x1100, 0xd1c1, 0xd081, 0x1040,

    0xf001, 0x30c0, 0x3180, 0xf141, 0x3300, 0xf3c1, 0xf281, 0x3240,

    0x3600, 0xf6c1, 0xf781, 0x3740, 0xf501, 0x35c0, 0x3480, 0xf441,

    0x3c00, 0xfcc1, 0xfd81, 0x3d40, 0xff01, 0x3fc0, 0x3e80, 0xfe41,

    0xfa01, 0x3ac0, 0x3b80, 0xfb41, 0x3900, 0xf9c1, 0xf881, 0x3840,

    0x2800, 0xe8c1, 0xe981, 0x2940, 0xeb01, 0x2bc0, 0x2a80, 0xea41,

    0xee01, 0x2ec0, 0x2f80, 0xef41, 0x2d00, 0xedc1, 0xec81, 0x2c40,

    0xe401, 0x24c0, 0x2580, 0xe541, 0x2700, 0xe7c1, 0xe681, 0x2640,

    0x2200, 0xe2c1, 0xe381, 0x2340, 0xe101, 0x21c0, 0x2080, 0xe041,

    0xa001, 0x60c0, 0x6180, 0xa141, 0x6300, 0xa3c1, 0xa281, 0x6240,

    0x6600, 0xa6c1, 0xa781, 0x6740, 0xa501, 0x65c0, 0x6480, 0xa441,

    0x6c00, 0xacc1, 0xad81, 0x6d40, 0xaf01, 0x6fc0, 0x6e80, 0xae41,

    0xaa01, 0x6ac0, 0x6b80, 0xab41, 0x6900, 0xa9c1, 0xa881, 0x6840,

    0x7800, 0xb8c1, 0xb981, 0x7940, 0xbb01, 0x7bc0, 0x7a80, 0xba41,

    0xbe01, 0x7ec0, 0x7f80, 0xbf41, 0x7d00, 0xbdc1, 0xbc81, 0x7c40,

    0xb401, 0x74c0, 0x7580, 0xb541, 0x7700, 0xb7c1, 0xb681, 0x7640,

    0x7200, 0xb2c1, 0xb381, 0x7340, 0xb101, 0x71c0, 0x7080, 0xb041,

    0x5000, 0x90c1, 0x9181, 0x5140, 0x9301, 0x53c0, 0x5280, 0x9241,

    0x9601, 0x56c0, 0x5780, 0x9741, 0x5500, 0x95c1, 0x9481, 0x5440,

    0x9c01, 0x5cc0, 0x5d80, 0x9d41, 0x5f00, 0x9fc1, 0x9e81, 0x5e40,

    0x5a00, 0x9ac1, 0x9b81, 0x5b40, 0x9901, 0x59c0, 0x5880, 0x9841,

    0x8801, 0x48c0, 0x4980, 0x8941, 0x4b00, 0x8bc1, 0x8a81, 0x4a40,

    0x4e00, 0x8ec1, 0x8f81, 0x4f40, 0x8d01, 0x4dc0, 0x4c80, 0x8c41,

    0x4400, 0x84c1, 0x8581, 0x4540, 0x8701, 0x47c0, 0x4680, 0x8641,

    0x8201, 0x42c0, 0x4380, 0x8341, 0x4100, 0x81c1, 0x8081, 0x4040,

};

static uint16_t l2cap_fcs16(const uint8_t *message, int len)

{

    uint16_t fcs = 0x0000;

    while (len --)

#if 0

    {

        int i;

        fcs ^= *message ++;

        for (i = 8; i; -- i)

            if (fcs & 1)

                fcs = (fcs >> 1) ^ 0xa001;

            else

                fcs = (fcs >> 1);

    }

#else

        fcs = (fcs >> 8) ^ l2cap_fcs16_table[(fcs ^ *message ++) & 0xff];

#endif

    return fcs;

}

/* L2CAP layer logic (protocol) */

static void l2cap_retransmission_timer_update(struct l2cap_chan_s *ch)

{

#if 0

    if (ch->mode != L2CAP_MODE_BASIC && ch->rexmit)

        qemu_mod_timer(ch->retransmission_timer);

    else

        qemu_del_timer(ch->retransmission_timer);

#endif

}

static void l2cap_monitor_timer_update(struct l2cap_chan_s *ch)

{

#if 0

    if (ch->mode != L2CAP_MODE_BASIC && !ch->rexmit)

        qemu_mod_timer(ch->monitor_timer);

    else

        qemu_del_timer(ch->monitor_timer);

#endif

}

static void l2cap_command_reject(struct l2cap_instance_s *l2cap, int id,

                uint16_t reason, const void *data, int plen)

{

    uint8_t *pkt;

    l2cap_cmd_hdr *hdr;

    l2cap_cmd_rej *params;

    uint16_t len;

    reason = cpu_to_le16(reason);

    len = cpu_to_le16(L2CAP_CMD_REJ_SIZE + plen);

    pkt = l2cap->signalling_ch.params.sdu_out(&l2cap->signalling_ch.params,

                    L2CAP_CMD_HDR_SIZE + L2CAP_CMD_REJ_SIZE + plen);

    hdr = (void *) (pkt + 0);

    params = (void *) (pkt + L2CAP_CMD_HDR_SIZE);

    hdr->code = L2CAP_COMMAND_REJ;

    hdr->ident = id;

    memcpy(&hdr->len, &len, sizeof(hdr->len));

    memcpy(&params->reason, &reason, sizeof(reason));

    if (plen)

       memcpy(pkt + L2CAP_CMD_HDR_SIZE + L2CAP_CMD_REJ_SIZE, data, plen);

    l2cap->signalling_ch.params.sdu_submit(&l2cap->signalling_ch.params);

}

static void l2cap_command_reject_cid(struct l2cap_instance_s *l2cap, int id,

                uint16_t reason, uint16_t dcid, uint16_t scid)

{

    l2cap_cmd_rej_cid params = {

        .dcid = dcid,

        .scid = scid,

    };

    l2cap_command_reject(l2cap, id, reason, &params, L2CAP_CMD_REJ_CID_SIZE);

}

static void l2cap_connection_response(struct l2cap_instance_s *l2cap,

                int dcid, int scid, int result, int status)

{

    uint8_t *pkt;

    l2cap_cmd_hdr *hdr;

    l2cap_conn_rsp *params;

    pkt = l2cap->signalling_ch.params.sdu_out(&l2cap->signalling_ch.params,

                    L2CAP_CMD_HDR_SIZE + L2CAP_CONN_RSP_SIZE);

    hdr = (void *) (pkt + 0);

    params = (void *) (pkt + L2CAP_CMD_HDR_SIZE);

    hdr->code = L2CAP_CONN_RSP;

    hdr->ident = l2cap->last_id;

    hdr->len = cpu_to_le16(L2CAP_CONN_RSP_SIZE);

    params->dcid = cpu_to_le16(dcid);

    params->scid = cpu_to_le16(scid);

    params->result = cpu_to_le16(result);

    params->status = cpu_to_le16(status);

    l2cap->signalling_ch.params.sdu_submit(&l2cap->signalling_ch.params);

}

static void l2cap_configuration_request(struct l2cap_instance_s *l2cap,

                int dcid, int flag, const uint8_t *data, int len)

{

    uint8_t *pkt;

    l2cap_cmd_hdr *hdr;

    l2cap_conf_req *params;

    pkt = l2cap->signalling_ch.params.sdu_out(&l2cap->signalling_ch.params,

                    L2CAP_CMD_HDR_SIZE + L2CAP_CONF_REQ_SIZE(len));

    hdr = (void *) (pkt + 0);

    params = (void *) (pkt + L2CAP_CMD_HDR_SIZE);

    /* TODO: unify the id sequencing */

    l2cap->last_id = l2cap->next_id;

    l2cap->next_id = l2cap->next_id == 255 ? 1 : l2cap->next_id + 1;

    hdr->code = L2CAP_CONF_REQ;

    hdr->ident = l2cap->last_id;

    hdr->len = cpu_to_le16(L2CAP_CONF_REQ_SIZE(len));

    params->dcid = cpu_to_le16(dcid);

    params->flags = cpu_to_le16(flag);

    if (len)

        memcpy(params->data, data, len);

    l2cap->signalling_ch.params.sdu_submit(&l2cap->signalling_ch.params);

}

static void l2cap_configuration_response(struct l2cap_instance_s *l2cap,

                int scid, int flag, int result, const uint8_t *data, int len)

{

    uint8_t *pkt;

    l2cap_cmd_hdr *hdr;

    l2cap_conf_rsp *params;

    pkt = l2cap->signalling_ch.params.sdu_out(&l2cap->signalling_ch.params,

                    L2CAP_CMD_HDR_SIZE + L2CAP_CONF_RSP_SIZE(len));

    hdr = (void *) (pkt + 0);

    params = (void *) (pkt + L2CAP_CMD_HDR_SIZE);

    hdr->code = L2CAP_CONF_RSP;

    hdr->ident = l2cap->last_id;

    hdr->len = cpu_to_le16(L2CAP_CONF_RSP_SIZE(len));

    params->scid = cpu_to_le16(scid);

    params->flags = cpu_to_le16(flag);

    params->result = cpu_to_le16(result);

    if (len)

        memcpy(params->data, data, len);

    l2cap->signalling_ch.params.sdu_submit(&l2cap->signalling_ch.params);

}

static void l2cap_disconnection_response(struct l2cap_instance_s *l2cap,

                int dcid, int scid)

{

    uint8_t *pkt;

    l2cap_cmd_hdr *hdr;

    l2cap_disconn_rsp *params;

    pkt = l2cap->signalling_ch.params.sdu_out(&l2cap->signalling_ch.params,

                    L2CAP_CMD_HDR_SIZE + L2CAP_DISCONN_RSP_SIZE);

    hdr = (void *) (pkt + 0);

    params = (void *) (pkt + L2CAP_CMD_HDR_SIZE);

    hdr->code = L2CAP_DISCONN_RSP;

    hdr->ident = l2cap->last_id;

    hdr->len = cpu_to_le16(L2CAP_DISCONN_RSP_SIZE);

    params->dcid = cpu_to_le16(dcid);

    params->scid = cpu_to_le16(scid);

    l2cap->signalling_ch.params.sdu_submit(&l2cap->signalling_ch.params);

}

static void l2cap_echo_response(struct l2cap_instance_s *l2cap,

                const uint8_t *data, int len)

{

    uint8_t *pkt;

    l2cap_cmd_hdr *hdr;

    uint8_t *params;

    pkt = l2cap->signalling_ch.params.sdu_out(&l2cap->signalling_ch.params,

                    L2CAP_CMD_HDR_SIZE + len);

    hdr = (void *) (pkt + 0);

    params = (void *) (pkt + L2CAP_CMD_HDR_SIZE);

    hdr->code = L2CAP_ECHO_RSP;

    hdr->ident = l2cap->last_id;

    hdr->len = cpu_to_le16(len);

    memcpy(params, data, len);

    l2cap->signalling_ch.params.sdu_submit(&l2cap->signalling_ch.params);

}

static void l2cap_info_response(struct l2cap_instance_s *l2cap, int type,

                int result, const uint8_t *data, int len)

{

    uint8_t *pkt;

    l2cap_cmd_hdr *hdr;

    l2cap_info_rsp *params;

    pkt = l2cap->signalling_ch.params.sdu_out(&l2cap->signalling_ch.params,

                    L2CAP_CMD_HDR_SIZE + L2CAP_INFO_RSP_SIZE + len);

    hdr = (void *) (pkt + 0);

    params = (void *) (pkt + L2CAP_CMD_HDR_SIZE);

    hdr->code = L2CAP_INFO_RSP;

    hdr->ident = l2cap->last_id;

    hdr->len = cpu_to_le16(L2CAP_INFO_RSP_SIZE + len);

    params->type = cpu_to_le16(type);

    params->result = cpu_to_le16(result);

    if (len)

       memcpy(params->data, data, len);

    l2cap->signalling_ch.params.sdu_submit(&l2cap->signalling_ch.params);

}

static uint8_t *l2cap_bframe_out(struct bt_l2cap_conn_params_s *parm, int len);

static void l2cap_bframe_submit(struct bt_l2cap_conn_params_s *parms);

#if 0

static uint8_t *l2cap_iframe_out(struct bt_l2cap_conn_params_s *parm, int len);

static void l2cap_iframe_submit(struct bt_l2cap_conn_params_s *parm);

#endif

static void l2cap_bframe_in(struct l2cap_chan_s *ch, uint16_t cid,

                const l2cap_hdr *hdr, int len);

static void l2cap_iframe_in(struct l2cap_chan_s *ch, uint16_t cid,

                const l2cap_hdr *hdr, int len);

static int l2cap_cid_new(struct l2cap_instance_s *l2cap)

{

    int i;

    for (i = L2CAP_CID_ALLOC; i < L2CAP_CID_MAX; i ++)

        if (!l2cap->cid[i])

            return i;

    return L2CAP_CID_INVALID;

}

static inline struct bt_l2cap_psm_s *l2cap_psm(

                struct bt_l2cap_device_s *device, int psm)

{

    struct bt_l2cap_psm_s *ret = device->first_psm;

    while (ret && ret->psm != psm)

        ret = ret->next;

    return ret;

}

static struct l2cap_chan_s *l2cap_channel_open(struct l2cap_instance_s *l2cap,

                int psm, int source_cid)

{

    struct l2cap_chan_s *ch = 0;

    struct bt_l2cap_psm_s *psm_info;

    int result, status;

    int cid = l2cap_cid_new(l2cap);

    if (cid) {

        /* See what the channel is to be used for.. */

        psm_info = l2cap_psm(l2cap->dev, psm);

        if (psm_info) {

            /* Device supports this use-case.  */

            ch = qemu_mallocz(sizeof(*ch));

            ch->params.sdu_out = l2cap_bframe_out;

            ch->params.sdu_submit = l2cap_bframe_submit;

            ch->frame_in = l2cap_bframe_in;

            ch->mps = 65536;

            ch->min_mtu = MAX(48, psm_info->min_mtu);

            ch->params.remote_mtu = MAX(672, ch->min_mtu);

            ch->remote_cid = source_cid;

            ch->mode = L2CAP_MODE_BASIC;

            ch->l2cap = l2cap;

            /* Does it feel like opening yet another channel though?  */

            if (!psm_info->new_channel(l2cap->dev, &ch->params)) {

                l2cap->cid[cid] = ch;

                result = L2CAP_CR_SUCCESS;

                status = L2CAP_CS_NO_INFO;

            } else {

                qemu_free(ch);

                result = L2CAP_CR_NO_MEM;

                status = L2CAP_CS_NO_INFO;

            }

        } else {

            result = L2CAP_CR_BAD_PSM;

            status = L2CAP_CS_NO_INFO;

        }

    } else {

        result = L2CAP_CR_NO_MEM;

        status = L2CAP_CS_NO_INFO;

    }

    l2cap_connection_response(l2cap, cid, source_cid, result, status);

    return ch;

}

static void l2cap_channel_close(struct l2cap_instance_s *l2cap,

                int cid, int source_cid)

{

    struct l2cap_chan_s *ch = 0;

    /* According to Volume 3, section 6.1.1, pg 1048 of BT Core V2.0, a

     * connection in CLOSED state still responds with a L2CAP_DisconnectRsp

     * message on an L2CAP_DisconnectReq event.  */

    if (unlikely(cid < L2CAP_CID_ALLOC)) {

        l2cap_command_reject_cid(l2cap, l2cap->last_id, L2CAP_REJ_CID_INVAL,

                        cid, source_cid);

        return;

    }

    if (likely(cid >= L2CAP_CID_ALLOC && cid < L2CAP_CID_MAX))

        ch = l2cap->cid[cid];

    if (likely(ch)) {

        if (ch->remote_cid != source_cid) {

            fprintf(stderr, "%s: Ignoring a Disconnection Request with the "

                            "invalid SCID %04x.\n", __FUNCTION__, source_cid);

            return;

        }

        l2cap->cid[cid] = 0;

        ch->params.close(ch->params.opaque);

        qemu_free(ch);

    }

    l2cap_disconnection_response(l2cap, cid, source_cid);

}

static void l2cap_channel_config_null(struct l2cap_instance_s *l2cap,

                struct l2cap_chan_s *ch)

{

    l2cap_configuration_request(l2cap, ch->remote_cid, 0, 0, 0);

    ch->config_req_id = l2cap->last_id;

    ch->config &= ~L2CAP_CFG_INIT;

}

static void l2cap_channel_config_req_event(struct l2cap_instance_s *l2cap,

                struct l2cap_chan_s *ch)

{

    /* Use all default channel options and terminate negotiation.  */

    l2cap_channel_config_null(l2cap, ch);

}

static int l2cap_channel_config(struct l2cap_instance_s *l2cap,

                struct l2cap_chan_s *ch, int flag,

                const uint8_t *data, int len)

{

    l2cap_conf_opt *opt;

    l2cap_conf_opt_qos *qos;

    uint32_t val;

    uint8_t rsp[len];

    int result = L2CAP_CONF_SUCCESS;

    data = memcpy(rsp, data, len);

    while (len) {

        opt = (void *) data;

        if (len < L2CAP_CONF_OPT_SIZE ||

                        len < L2CAP_CONF_OPT_SIZE + opt->len) {

            result = L2CAP_CONF_REJECT;

            break;

        }

        data += L2CAP_CONF_OPT_SIZE + opt->len;

        len -= L2CAP_CONF_OPT_SIZE + opt->len;

        switch (opt->type & 0x7f) {

        case L2CAP_CONF_MTU:

            if (opt->len != 2) {

                result = L2CAP_CONF_REJECT;

                break;

            }

            /* MTU */

            val = le16_to_cpup((void *) opt->val);

            if (val < ch->min_mtu) {

                cpu_to_le16w((void *) opt->val, ch->min_mtu);

                result = L2CAP_CONF_UNACCEPT;

                break;

            }

            ch->params.remote_mtu = val;

            break;

        case L2CAP_CONF_FLUSH_TO:

            if (opt->len != 2) {

                result = L2CAP_CONF_REJECT;

                break;

            }

            /* Flush Timeout */

            val = le16_to_cpup((void *) opt->val);

            if (val < 0x0001) {

                opt->val[0] = 0xff;

                opt->val[1] = 0xff;

                result = L2CAP_CONF_UNACCEPT;

                break;

            }

            break;

        case L2CAP_CONF_QOS:

            if (opt->len != L2CAP_CONF_OPT_QOS_SIZE) {

                result = L2CAP_CONF_REJECT;

                break;

            }

            qos = (void *) opt->val;

            /* Flags */

            val = qos->flags;

            if (val) {

                qos->flags = 0;

                result = L2CAP_CONF_UNACCEPT;

            }

            /* Service type */

            val = qos->service_type;

            if (val != L2CAP_CONF_QOS_BEST_EFFORT &&

                            val != L2CAP_CONF_QOS_NO_TRAFFIC) {

                qos->service_type = L2CAP_CONF_QOS_BEST_EFFORT;

                result = L2CAP_CONF_UNACCEPT;

            }

            if (val != L2CAP_CONF_QOS_NO_TRAFFIC) {

                /* XXX: These values should possibly be calculated

                 * based on LM / baseband properties also.  */

                /* Token rate */

                val = le32_to_cpu(qos->token_rate);

                if (val == L2CAP_CONF_QOS_WILDCARD)

                    qos->token_rate = cpu_to_le32(0x100000);

                /* Token bucket size */

                val = le32_to_cpu(qos->token_bucket_size);

                if (val == L2CAP_CONF_QOS_WILDCARD)

                    qos->token_bucket_size = cpu_to_le32(65500);

                /* Any Peak bandwidth value is correct to return as-is */

                /* Any Access latency value is correct to return as-is */

                /* Any Delay variation value is correct to return as-is */

            }

            break;

        case L2CAP_CONF_RFC:

            if (opt->len != 9) {

                result = L2CAP_CONF_REJECT;

                break;

            }

            /* Mode */

            val = opt->val[0];

            switch (val) {

            case L2CAP_MODE_BASIC:

                ch->mode = val;

                ch->frame_in = l2cap_bframe_in;

                /* All other parameters shall be ignored */

                break;

            case L2CAP_MODE_RETRANS:

            case L2CAP_MODE_FLOWCTL:

                ch->mode = val;

                ch->frame_in = l2cap_iframe_in;

                /* Note: most of these parameters refer to incoming traffic

                 * so we don't need to save them as long as we can accept

                 * incoming PDUs at any values of the parameters.  */

                /* TxWindow size */

                val = opt->val[1];

                if (val < 1 || val > 32) {

                    opt->val[1] = 32;

                    result = L2CAP_CONF_UNACCEPT;

                    break;

                }

                /* MaxTransmit */

                val = opt->val[2];

                if (val < 1) {

                    opt->val[2] = 1;

                    result = L2CAP_CONF_UNACCEPT;

                    break;

                }

                /* Remote Retransmission time-out shouldn't affect local

                 * operation (?) */

                /* The Monitor time-out drives the local Monitor timer (?),

                 * so save the value.  */

                val = (opt->val[6] << 8) | opt->val[5];

                if (val < 30) {

                    opt->val[5] = 100 & 0xff;

                    opt->val[6] = 100 >> 8;

                    result = L2CAP_CONF_UNACCEPT;

                    break;

                }

                ch->monitor_timeout = val;

                l2cap_monitor_timer_update(ch);

                /* MPS */

                val = (opt->val[8] << 8) | opt->val[7];

                if (val < ch->min_mtu) {

                    opt->val[7] = ch->min_mtu & 0xff;

                    opt->val[8] = ch->min_mtu >> 8;

                    result = L2CAP_CONF_UNACCEPT;

                    break;

                }

                ch->mps = val;

                break;

            default:

                result = L2CAP_CONF_UNACCEPT;

                break;

            }

            break;

        default:

            if (!(opt->type >> 7))

                result = L2CAP_CONF_UNKNOWN;

            break;

        }

        if (result != L2CAP_CONF_SUCCESS)

            break;        /* XXX: should continue? */

    }

    l2cap_configuration_response(l2cap, ch->remote_cid,

                    flag, result, rsp, len);

    return result == L2CAP_CONF_SUCCESS && !flag;

}

static void l2cap_channel_config_req_msg(struct l2cap_instance_s *l2cap,

                int flag, int cid, const uint8_t *data, int len)

{

    struct l2cap_chan_s *ch;

    if (unlikely(cid >= L2CAP_CID_MAX || !l2cap->cid[cid])) {

        l2cap_command_reject_cid(l2cap, l2cap->last_id, L2CAP_REJ_CID_INVAL,

                        cid, 0x0000);

        return;

    }

    ch = l2cap->cid[cid];

    /* From OPEN go to WAIT_CONFIG_REQ and from WAIT_CONFIG_REQ_RSP to

     * WAIT_CONFIG_REQ_RSP.  This is assuming the transition chart for OPEN

     * on pg 1053, section 6.1.5, volume 3 of BT Core V2.0 has a mistake

     * and on options-acceptable we go back to OPEN and otherwise to

     * WAIT_CONFIG_REQ and not the other way.  */

    ch->config &= ~L2CAP_CFG_ACC;

    if (l2cap_channel_config(l2cap, ch, flag, data, len))

        /* Go to OPEN or WAIT_CONFIG_RSP */

        ch->config |= L2CAP_CFG_ACC;

    /* TODO: if the incoming traffic flow control or retransmission mode

     * changed then we probably need to also generate the

     * ConfigureChannel_Req event and set the outgoing traffic to the same

     * mode.  */

    if (!(ch->config & L2CAP_CFG_INIT) && (ch->config & L2CAP_CFG_ACC) &&

                    !ch->config_req_id)

        l2cap_channel_config_req_event(l2cap, ch);

}

static int l2cap_channel_config_rsp_msg(struct l2cap_instance_s *l2cap,

                int result, int flag, int cid, const uint8_t *data, int len)

{

    struct l2cap_chan_s *ch;

    if (unlikely(cid >= L2CAP_CID_MAX || !l2cap->cid[cid])) {

        l2cap_command_reject_cid(l2cap, l2cap->last_id, L2CAP_REJ_CID_INVAL,

                        cid, 0x0000);

        return 0;

    }

    ch = l2cap->cid[cid];

    if (ch->config_req_id != l2cap->last_id)

        return 1;

    ch->config_req_id = 0;

    if (result == L2CAP_CONF_SUCCESS) {

        if (!flag)

            ch->config |= L2CAP_CFG_INIT;

        else

            l2cap_channel_config_null(l2cap, ch);

    } else

        /* Retry until we succeed */

        l2cap_channel_config_req_event(l2cap, ch);

    return 0;

}

static void l2cap_channel_open_req_msg(struct l2cap_instance_s *l2cap,

                int psm, int source_cid)

{

    struct l2cap_chan_s *ch = l2cap_channel_open(l2cap, psm, source_cid);

    if (!ch)

        return;

    /* Optional */

    if (!(ch->config & L2CAP_CFG_INIT) && !ch->config_req_id)

        l2cap_channel_config_req_event(l2cap, ch);

}

static void l2cap_info(struct l2cap_instance_s *l2cap, int type)

{

    uint8_t data[4];

    int len = 0;

    int result = L2CAP_IR_SUCCESS;

    switch (type) {

    case L2CAP_IT_CL_MTU:

        data[len ++] = l2cap->group_ch.mps & 0xff;

        data[len ++] = l2cap->group_ch.mps >> 8;

        break;

    case L2CAP_IT_FEAT_MASK:

        /* (Prematurely) report Flow control and Retransmission modes.  */

        data[len ++] = 0x03;

        data[len ++] = 0x00;

        data[len ++] = 0x00;

        data[len ++] = 0x00;

        break;

    default:

        result = L2CAP_IR_NOTSUPP;

    }

    l2cap_info_response(l2cap, type, result, data, len);

}

static void l2cap_command(struct l2cap_instance_s *l2cap, int code, int id,

                const uint8_t *params, int len)

{

    int err;

#if 0

    /* TODO: do the IDs really have to be in sequence?  */

    if (!id || (id != l2cap->last_id && id != l2cap->next_id)) {

        fprintf(stderr, "%s: out of sequence command packet ignored.\n",

                        __FUNCTION__);

        return;

    }

#else

    l2cap->next_id = id;

#endif

    if (id == l2cap->next_id) {

        l2cap->last_id = l2cap->next_id;

        l2cap->next_id = l2cap->next_id == 255 ? 1 : l2cap->next_id + 1;

    } else {

        /* TODO: Need to re-send the same response, without re-executing

         * the corresponding command!  */

    }

    switch (code) {

    case L2CAP_COMMAND_REJ:

        if (unlikely(len != 2 && len != 4 && len != 6)) {

            err = L2CAP_REJ_CMD_NOT_UNDERSTOOD;

            goto reject;

        }

        /* We never issue commands other than Command Reject currently.  */

        fprintf(stderr, "%s: stray Command Reject (%02x, %04x) "

                        "packet, ignoring.\n", __FUNCTION__, id,

                        le16_to_cpu(((l2cap_cmd_rej *) params)->reason));

        break;

    case L2CAP_CONN_REQ:

        if (unlikely(len != L2CAP_CONN_REQ_SIZE)) {

            err = L2CAP_REJ_CMD_NOT_UNDERSTOOD;

            goto reject;

        }

        l2cap_channel_open_req_msg(l2cap,

                        le16_to_cpu(((l2cap_conn_req *) params)->psm),

                        le16_to_cpu(((l2cap_conn_req *) params)->scid));

        break;

    case L2CAP_CONN_RSP:

        if (unlikely(len != L2CAP_CONN_RSP_SIZE)) {

            err = L2CAP_REJ_CMD_NOT_UNDERSTOOD;

            goto reject;

        }

        /* We never issue Connection Requests currently. TODO  */

        fprintf(stderr, "%s: unexpected Connection Response (%02x) "

                        "packet, ignoring.\n", __FUNCTION__, id);

        break;

    case L2CAP_CONF_REQ:

        if (unlikely(len < L2CAP_CONF_REQ_SIZE(0))) {

            err = L2CAP_REJ_CMD_NOT_UNDERSTOOD;

            goto reject;

        }

        l2cap_channel_config_req_msg(l2cap,

                        le16_to_cpu(((l2cap_conf_req *) params)->flags) & 1,

                        le16_to_cpu(((l2cap_conf_req *) params)->dcid),

                        ((l2cap_conf_req *) params)->data,

                        len - L2CAP_CONF_REQ_SIZE(0));

        break;

    case L2CAP_CONF_RSP:

        if (unlikely(len < L2CAP_CONF_RSP_SIZE(0))) {

            err = L2CAP_REJ_CMD_NOT_UNDERSTOOD;

            goto reject;

        }

        if (l2cap_channel_config_rsp_msg(l2cap,

                        le16_to_cpu(((l2cap_conf_rsp *) params)->result),

                        le16_to_cpu(((l2cap_conf_rsp *) params)->flags) & 1,

                        le16_to_cpu(((l2cap_conf_rsp *) params)->scid),

                        ((l2cap_conf_rsp *) params)->data,

                        len - L2CAP_CONF_RSP_SIZE(0)))

            fprintf(stderr, "%s: unexpected Configure Response (%02x) "

                            "packet, ignoring.\n", __FUNCTION__, id);

        break;

    case L2CAP_DISCONN_REQ:

        if (unlikely(len != L2CAP_DISCONN_REQ_SIZE)) {

            err = L2CAP_REJ_CMD_NOT_UNDERSTOOD;

            goto reject;

        }

        l2cap_channel_close(l2cap,

                        le16_to_cpu(((l2cap_disconn_req *) params)->dcid),

                        le16_to_cpu(((l2cap_disconn_req *) params)->scid));

        break;