llc_c_ac.c

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/*
 * llc_c_ac.c - actions performed during connection state transition.
 *
 * Description:
 *   Functions in this module are implementation of connection component actions
 *   Details of actions can be found in IEEE-802.2 standard document.
 *   All functions have one connection and one event as input argument. All of
 *   them return 0 On success and 1 otherwise.
 *
 * Copyright (c) 1997 by Procom Technology, Inc.
 *       2001-2003 by Arnaldo Carvalho de Melo <[email protected]>
 *
 * This program can be redistributed or modified under the terms of the
 * GNU General Public License as published by the Free Software Foundation.
 * This program is distributed without any warranty or implied warranty
 * of merchantability or fitness for a particular purpose.
 *
 * See the GNU General Public License for more details.
 */
#include <linux/netdevice.h>
#include <linux/slab.h>
#include <net/llc_conn.h>
#include <net/llc_sap.h>
#include <net/sock.h>
#include <net/llc_c_ev.h>
#include <net/llc_c_ac.h>
#include <net/llc_c_st.h>
#include <net/llc_pdu.h>
#include <net/llc.h>


static int llc_conn_ac_inc_vs_by_1(struct sock *sk, struct sk_buff *skb);
static void llc_process_tmr_ev(struct sock *sk, struct sk_buff *skb);
static int llc_conn_ac_data_confirm(struct sock *sk, struct sk_buff *ev);

static int llc_conn_ac_inc_npta_value(struct sock *sk, struct sk_buff *skb);

static int llc_conn_ac_send_rr_rsp_f_set_ackpf(struct sock *sk,
                           struct sk_buff *skb);

static int llc_conn_ac_set_p_flag_1(struct sock *sk, struct sk_buff *skb);

#define INCORRECT 0

int llc_conn_ac_clear_remote_busy(struct sock *sk, struct sk_buff *skb)
{
    struct llc_sock *llc = llc_sk(sk);

    if (llc->remote_busy_flag) {
        u8 nr;
        struct llc_pdu_sn *pdu = llc_pdu_sn_hdr(skb);

        llc->remote_busy_flag = 0;
        del_timer(&llc->busy_state_timer.timer);
        nr = LLC_I_GET_NR(pdu);
        llc_conn_resend_i_pdu_as_cmd(sk, nr, 0);
    }
    return 0;
}

int llc_conn_ac_conn_ind(struct sock *sk, struct sk_buff *skb)
{
    struct llc_conn_state_ev *ev = llc_conn_ev(skb);

    ev->ind_prim = LLC_CONN_PRIM;
    return 0;
}

int llc_conn_ac_conn_confirm(struct sock *sk, struct sk_buff *skb)
{
    struct llc_conn_state_ev *ev = llc_conn_ev(skb);

    ev->cfm_prim = LLC_CONN_PRIM;
    return 0;
}

static int llc_conn_ac_data_confirm(struct sock *sk, struct sk_buff *skb)
{
    struct llc_conn_state_ev *ev = llc_conn_ev(skb);

    ev->cfm_prim = LLC_DATA_PRIM;
    return 0;
}

int llc_conn_ac_data_ind(struct sock *sk, struct sk_buff *skb)
{
    llc_conn_rtn_pdu(sk, skb);
    return 0;
}

int llc_conn_ac_disc_ind(struct sock *sk, struct sk_buff *skb)
{
    struct llc_conn_state_ev *ev = llc_conn_ev(skb);
    u8 reason = 0;
    int rc = 0;

    if (ev->type == LLC_CONN_EV_TYPE_PDU) {
        struct llc_pdu_un *pdu = llc_pdu_un_hdr(skb);

        if (LLC_PDU_IS_RSP(pdu) &&
            LLC_PDU_TYPE_IS_U(pdu) &&
            LLC_U_PDU_RSP(pdu) == LLC_2_PDU_RSP_DM)
            reason = LLC_DISC_REASON_RX_DM_RSP_PDU;
        else if (LLC_PDU_IS_CMD(pdu) &&
               LLC_PDU_TYPE_IS_U(pdu) &&
               LLC_U_PDU_CMD(pdu) == LLC_2_PDU_CMD_DISC)
            reason = LLC_DISC_REASON_RX_DISC_CMD_PDU;
    } else if (ev->type == LLC_CONN_EV_TYPE_ACK_TMR)
        reason = LLC_DISC_REASON_ACK_TMR_EXP;
    else
        rc = -EINVAL;
    if (!rc) {
        ev->reason   = reason;
        ev->ind_prim = LLC_DISC_PRIM;
    }
    return rc;
}

int llc_conn_ac_disc_confirm(struct sock *sk, struct sk_buff *skb)
{
    struct llc_conn_state_ev *ev = llc_conn_ev(skb);

    ev->reason   = ev->status;
    ev->cfm_prim = LLC_DISC_PRIM;
    return 0;
}

int llc_conn_ac_rst_ind(struct sock *sk, struct sk_buff *skb)
{
    u8 reason = 0;
    int rc = 1;
    struct llc_conn_state_ev *ev = llc_conn_ev(skb);
    struct llc_pdu_un *pdu = llc_pdu_un_hdr(skb);
    struct llc_sock *llc = llc_sk(sk);

    switch (ev->type) {
    case LLC_CONN_EV_TYPE_PDU:
        if (LLC_PDU_IS_RSP(pdu) &&
            LLC_PDU_TYPE_IS_U(pdu) &&
            LLC_U_PDU_RSP(pdu) == LLC_2_PDU_RSP_FRMR) {
            reason = LLC_RESET_REASON_LOCAL;
            rc = 0;
        } else if (LLC_PDU_IS_CMD(pdu) &&
               LLC_PDU_TYPE_IS_U(pdu) &&
               LLC_U_PDU_CMD(pdu) == LLC_2_PDU_CMD_SABME) {
            reason = LLC_RESET_REASON_REMOTE;
            rc = 0;
        }
        break;
    case LLC_CONN_EV_TYPE_ACK_TMR:
    case LLC_CONN_EV_TYPE_P_TMR:
    case LLC_CONN_EV_TYPE_REJ_TMR:
    case LLC_CONN_EV_TYPE_BUSY_TMR:
        if (llc->retry_count > llc->n2) {
            reason = LLC_RESET_REASON_LOCAL;
            rc = 0;
        }
        break;
    }
    if (!rc) {
        ev->reason   = reason;
        ev->ind_prim = LLC_RESET_PRIM;
    }
    return rc;
}

int llc_conn_ac_rst_confirm(struct sock *sk, struct sk_buff *skb)
{
    struct llc_conn_state_ev *ev = llc_conn_ev(skb);

    ev->reason   = 0;
    ev->cfm_prim = LLC_RESET_PRIM;
    return 0;
}

int llc_conn_ac_clear_remote_busy_if_f_eq_1(struct sock *sk,
                        struct sk_buff *skb)
{
    struct llc_pdu_sn *pdu = llc_pdu_sn_hdr(skb);

    if (LLC_PDU_IS_RSP(pdu) &&
        LLC_PDU_TYPE_IS_I(pdu) &&
        LLC_I_PF_IS_1(pdu) && llc_sk(sk)->ack_pf)
        llc_conn_ac_clear_remote_busy(sk, skb);
    return 0;
}

int llc_conn_ac_stop_rej_tmr_if_data_flag_eq_2(struct sock *sk,
                           struct sk_buff *skb)
{
    struct llc_sock *llc = llc_sk(sk);

    if (llc->data_flag == 2)
        del_timer(&llc->rej_sent_timer.timer);
    return 0;
}

int llc_conn_ac_send_disc_cmd_p_set_x(struct sock *sk, struct sk_buff *skb)
{
    int rc = -ENOBUFS;
    struct llc_sock *llc = llc_sk(sk);
    struct sk_buff *nskb = llc_alloc_frame(sk, llc->dev, LLC_PDU_TYPE_U, 0);

    if (nskb) {
        struct llc_sap *sap = llc->sap;

        llc_pdu_header_init(nskb, LLC_PDU_TYPE_U, sap->laddr.lsap,
                    llc->daddr.lsap, LLC_PDU_CMD);
        llc_pdu_init_as_disc_cmd(nskb, 1);
        rc = llc_mac_hdr_init(nskb, llc->dev->dev_addr, llc->daddr.mac);
        if (unlikely(rc))
            goto free;
        llc_conn_send_pdu(sk, nskb);
        llc_conn_ac_set_p_flag_1(sk, skb);
    }
out:
    return rc;
free:
    kfree_skb(nskb);
    goto out;
}

int llc_conn_ac_send_dm_rsp_f_set_p(struct sock *sk, struct sk_buff *skb)
{
    int rc = -ENOBUFS;
    struct llc_sock *llc = llc_sk(sk);
    struct sk_buff *nskb = llc_alloc_frame(sk, llc->dev, LLC_PDU_TYPE_U, 0);

    if (nskb) {
        struct llc_sap *sap = llc->sap;
        u8 f_bit;

        llc_pdu_decode_pf_bit(skb, &f_bit);
        llc_pdu_header_init(nskb, LLC_PDU_TYPE_U, sap->laddr.lsap,
                    llc->daddr.lsap, LLC_PDU_RSP);
        llc_pdu_init_as_dm_rsp(nskb, f_bit);
        rc = llc_mac_hdr_init(nskb, llc->dev->dev_addr, llc->daddr.mac);
        if (unlikely(rc))
            goto free;
        llc_conn_send_pdu(sk, nskb);
    }
out:
    return rc;
free:
    kfree_skb(nskb);
    goto out;
}

int llc_conn_ac_send_dm_rsp_f_set_1(struct sock *sk, struct sk_buff *skb)
{
    int rc = -ENOBUFS;
    struct llc_sock *llc = llc_sk(sk);
    struct sk_buff *nskb = llc_alloc_frame(sk, llc->dev, LLC_PDU_TYPE_U, 0);

    if (nskb) {
        struct llc_sap *sap = llc->sap;

        llc_pdu_header_init(nskb, LLC_PDU_TYPE_U, sap->laddr.lsap,
                    llc->daddr.lsap, LLC_PDU_RSP);
        llc_pdu_init_as_dm_rsp(nskb, 1);
        rc = llc_mac_hdr_init(nskb, llc->dev->dev_addr, llc->daddr.mac);
        if (unlikely(rc))
            goto free;
        llc_conn_send_pdu(sk, nskb);
    }
out:
    return rc;
free:
    kfree_skb(nskb);
    goto out;
}

int llc_conn_ac_send_frmr_rsp_f_set_x(struct sock *sk, struct sk_buff *skb)
{
    u8 f_bit;
    int rc = -ENOBUFS;
    struct sk_buff *nskb;
    struct llc_pdu_sn *pdu = llc_pdu_sn_hdr(skb);
    struct llc_sock *llc = llc_sk(sk);

    llc->rx_pdu_hdr = *((u32 *)pdu);
    if (LLC_PDU_IS_CMD(pdu))
        llc_pdu_decode_pf_bit(skb, &f_bit);
    else
        f_bit = 0;
    nskb = llc_alloc_frame(sk, llc->dev, LLC_PDU_TYPE_U,
                   sizeof(struct llc_frmr_info));
    if (nskb) {
        struct llc_sap *sap = llc->sap;

        llc_pdu_header_init(nskb, LLC_PDU_TYPE_U, sap->laddr.lsap,
                    llc->daddr.lsap, LLC_PDU_RSP);
        llc_pdu_init_as_frmr_rsp(nskb, pdu, f_bit, llc->vS,
                     llc->vR, INCORRECT);
        rc = llc_mac_hdr_init(nskb, llc->dev->dev_addr, llc->daddr.mac);
        if (unlikely(rc))
            goto free;
        llc_conn_send_pdu(sk, nskb);
    }
out:
    return rc;
free:
    kfree_skb(nskb);
    goto out;
}

int llc_conn_ac_resend_frmr_rsp_f_set_0(struct sock *sk, struct sk_buff *skb)
{
    int rc = -ENOBUFS;
    struct llc_sock *llc = llc_sk(sk);
    struct sk_buff *nskb = llc_alloc_frame(sk, llc->dev, LLC_PDU_TYPE_U,
                           sizeof(struct llc_frmr_info));

    if (nskb) {
        struct llc_sap *sap = llc->sap;
        struct llc_pdu_sn *pdu = (struct llc_pdu_sn *)&llc->rx_pdu_hdr;

        llc_pdu_header_init(nskb, LLC_PDU_TYPE_U, sap->laddr.lsap,
                    llc->daddr.lsap, LLC_PDU_RSP);
        llc_pdu_init_as_frmr_rsp(nskb, pdu, 0, llc->vS,
                     llc->vR, INCORRECT);
        rc = llc_mac_hdr_init(nskb, llc->dev->dev_addr, llc->daddr.mac);
        if (unlikely(rc))
            goto free;
        llc_conn_send_pdu(sk, nskb);
    }
out:
    return rc;
free:
    kfree_skb(nskb);
    goto out;
}

int llc_conn_ac_resend_frmr_rsp_f_set_p(struct sock *sk, struct sk_buff *skb)
{
    u8 f_bit;
    int rc = -ENOBUFS;
    struct sk_buff *nskb;
    struct llc_sock *llc = llc_sk(sk);

    llc_pdu_decode_pf_bit(skb, &f_bit);
    nskb = llc_alloc_frame(sk, llc->dev, LLC_PDU_TYPE_U,
                   sizeof(struct llc_frmr_info));
    if (nskb) {
        struct llc_sap *sap = llc->sap;
        struct llc_pdu_sn *pdu = llc_pdu_sn_hdr(skb);

        llc_pdu_header_init(nskb, LLC_PDU_TYPE_U, sap->laddr.lsap,
                    llc->daddr.lsap, LLC_PDU_RSP);
        llc_pdu_init_as_frmr_rsp(nskb, pdu, f_bit, llc->vS,
                     llc->vR, INCORRECT);
        rc = llc_mac_hdr_init(nskb, llc->dev->dev_addr, llc->daddr.mac);
        if (unlikely(rc))
            goto free;
        llc_conn_send_pdu(sk, nskb);
    }
out:
    return rc;
free:
    kfree_skb(nskb);
    goto out;
}

int llc_conn_ac_send_i_cmd_p_set_1(struct sock *sk, struct sk_buff *skb)
{
    int rc;
    struct llc_sock *llc = llc_sk(sk);
    struct llc_sap *sap = llc->sap;

    llc_pdu_header_init(skb, LLC_PDU_TYPE_I, sap->laddr.lsap,
                llc->daddr.lsap, LLC_PDU_CMD);
    llc_pdu_init_as_i_cmd(skb, 1, llc->vS, llc->vR);
    rc = llc_mac_hdr_init(skb, llc->dev->dev_addr, llc->daddr.mac);
    if (likely(!rc)) {
        llc_conn_send_pdu(sk, skb);
        llc_conn_ac_inc_vs_by_1(sk, skb);
    }
    return rc;
}

static int llc_conn_ac_send_i_cmd_p_set_0(struct sock *sk, struct sk_buff *skb)
{
    int rc;
    struct llc_sock *llc = llc_sk(sk);
    struct llc_sap *sap = llc->sap;

    llc_pdu_header_init(skb, LLC_PDU_TYPE_I, sap->laddr.lsap,
                llc->daddr.lsap, LLC_PDU_CMD);
    llc_pdu_init_as_i_cmd(skb, 0, llc->vS, llc->vR);
    rc = llc_mac_hdr_init(skb, llc->dev->dev_addr, llc->daddr.mac);
    if (likely(!rc)) {
        llc_conn_send_pdu(sk, skb);
        llc_conn_ac_inc_vs_by_1(sk, skb);
    }
    return rc;
}

int llc_conn_ac_send_i_xxx_x_set_0(struct sock *sk, struct sk_buff *skb)
{
    int rc;
    struct llc_sock *llc = llc_sk(sk);
    struct llc_sap *sap = llc->sap;

    llc_pdu_header_init(skb, LLC_PDU_TYPE_I, sap->laddr.lsap,
                llc->daddr.lsap, LLC_PDU_CMD);
    llc_pdu_init_as_i_cmd(skb, 0, llc->vS, llc->vR);
    rc = llc_mac_hdr_init(skb, llc->dev->dev_addr, llc->daddr.mac);
    if (likely(!rc)) {
        llc_conn_send_pdu(sk, skb);
        llc_conn_ac_inc_vs_by_1(sk, skb);
    }
    return 0;
}

int llc_conn_ac_resend_i_xxx_x_set_0(struct sock *sk, struct sk_buff *skb)
{
    struct llc_pdu_sn *pdu = llc_pdu_sn_hdr(skb);
    u8 nr = LLC_I_GET_NR(pdu);

    llc_conn_resend_i_pdu_as_cmd(sk, nr, 0);
    return 0;
}

int llc_conn_ac_resend_i_xxx_x_set_0_or_send_rr(struct sock *sk,
                        struct sk_buff *skb)
{
    u8 nr;
    struct llc_pdu_sn *pdu = llc_pdu_sn_hdr(skb);
    int rc = -ENOBUFS;
    struct llc_sock *llc = llc_sk(sk);
    struct sk_buff *nskb = llc_alloc_frame(sk, llc->dev, LLC_PDU_TYPE_U, 0);

    if (nskb) {
        struct llc_sap *sap = llc->sap;

        llc_pdu_header_init(nskb, LLC_PDU_TYPE_U, sap->laddr.lsap,
                    llc->daddr.lsap, LLC_PDU_RSP);
        llc_pdu_init_as_rr_rsp(nskb, 0, llc->vR);
        rc = llc_mac_hdr_init(nskb, llc->dev->dev_addr, llc->daddr.mac);
        if (likely(!rc))
            llc_conn_send_pdu(sk, nskb);
        else
            kfree_skb(skb);
    }
    if (rc) {
        nr = LLC_I_GET_NR(pdu);
        rc = 0;
        llc_conn_resend_i_pdu_as_cmd(sk, nr, 0);
    }
    return rc;
}

int llc_conn_ac_resend_i_rsp_f_set_1(struct sock *sk, struct sk_buff *skb)
{
    struct llc_pdu_sn *pdu = llc_pdu_sn_hdr(skb);
    u8 nr = LLC_I_GET_NR(pdu);

    llc_conn_resend_i_pdu_as_rsp(sk, nr, 1);
    return 0;
}

int llc_conn_ac_send_rej_cmd_p_set_1(struct sock *sk, struct sk_buff *skb)
{
    int rc = -ENOBUFS;
    struct llc_sock *llc = llc_sk(sk);
    struct sk_buff *nskb = llc_alloc_frame(sk, llc->dev, LLC_PDU_TYPE_S, 0);

    if (nskb) {
        struct llc_sap *sap = llc->sap;

        llc_pdu_header_init(nskb, LLC_PDU_TYPE_S, sap->laddr.lsap,
                    llc->daddr.lsap, LLC_PDU_CMD);
        llc_pdu_init_as_rej_cmd(nskb, 1, llc->vR);
        rc = llc_mac_hdr_init(nskb, llc->dev->dev_addr, llc->daddr.mac);
        if (unlikely(rc))
            goto free;
        llc_conn_send_pdu(sk, nskb);
    }
out:
    return rc;
free:
    kfree_skb(nskb);
    goto out;
}

int llc_conn_ac_send_rej_rsp_f_set_1(struct sock *sk, struct sk_buff *skb)
{
    int rc = -ENOBUFS;
    struct llc_sock *llc = llc_sk(sk);
    struct sk_buff *nskb = llc_alloc_frame(sk, llc->dev, LLC_PDU_TYPE_S, 0);

    if (nskb) {
        struct llc_sap *sap = llc->sap;

        llc_pdu_header_init(nskb, LLC_PDU_TYPE_S, sap->laddr.lsap,
                    llc->daddr.lsap, LLC_PDU_RSP);
        llc_pdu_init_as_rej_rsp(nskb, 1, llc->vR);
        rc = llc_mac_hdr_init(nskb, llc->dev->dev_addr, llc->daddr.mac);
        if (unlikely(rc))
            goto free;
        llc_conn_send_pdu(sk, nskb);
    }
out:
    return rc;
free:
    kfree_skb(nskb);
    goto out;
}

int llc_conn_ac_send_rej_xxx_x_set_0(struct sock *sk, struct sk_buff *skb)
{
    int rc = -ENOBUFS;
    struct llc_sock *llc = llc_sk(sk);
    struct sk_buff *nskb = llc_alloc_frame(sk, llc->dev, LLC_PDU_TYPE_S, 0);

    if (nskb) {
        struct llc_sap *sap = llc->sap;

        llc_pdu_header_init(nskb, LLC_PDU_TYPE_S, sap->laddr.lsap,
                    llc->daddr.lsap, LLC_PDU_RSP);
        llc_pdu_init_as_rej_rsp(nskb, 0, llc->vR);
        rc = llc_mac_hdr_init(nskb, llc->dev->dev_addr, llc->daddr.mac);
        if (unlikely(rc))
            goto free;
        llc_conn_send_pdu(sk, nskb);
    }
out:
    return rc;
free:
    kfree_skb(nskb);
    goto out;
}

int llc_conn_ac_send_rnr_cmd_p_set_1(struct sock *sk, struct sk_buff *skb)
{
    int rc = -ENOBUFS;
    struct llc_sock *llc = llc_sk(sk);
    struct sk_buff *nskb = llc_alloc_frame(sk, llc->dev, LLC_PDU_TYPE_S, 0);

    if (nskb) {
        struct llc_sap *sap = llc->sap;

        llc_pdu_header_init(nskb, LLC_PDU_TYPE_S, sap->laddr.lsap,
                    llc->daddr.lsap, LLC_PDU_CMD);
        llc_pdu_init_as_rnr_cmd(nskb, 1, llc->vR);
        rc = llc_mac_hdr_init(nskb, llc->dev->dev_addr, llc->daddr.mac);
        if (unlikely(rc))
            goto free;
        llc_conn_send_pdu(sk, nskb);
    }
out:
    return rc;
free:
    kfree_skb(nskb);
    goto out;
}

int llc_conn_ac_send_rnr_rsp_f_set_1(struct sock *sk, struct sk_buff *skb)
{
    int rc = -ENOBUFS;
    struct llc_sock *llc = llc_sk(sk);
    struct sk_buff *nskb = llc_alloc_frame(sk, llc->dev, LLC_PDU_TYPE_S, 0);

    if (nskb) {
        struct llc_sap *sap = llc->sap;

        llc_pdu_header_init(nskb, LLC_PDU_TYPE_S, sap->laddr.lsap,
                    llc->daddr.lsap, LLC_PDU_RSP);
        llc_pdu_init_as_rnr_rsp(nskb, 1, llc->vR);
        rc = llc_mac_hdr_init(nskb, llc->dev->dev_addr, llc->daddr.mac);
        if (unlikely(rc))
            goto free;
        llc_conn_send_pdu(sk, nskb);
    }
out:
    return rc;
free:
    kfree_skb(nskb);
    goto out;
}

int llc_conn_ac_send_rnr_xxx_x_set_0(struct sock *sk, struct sk_buff *skb)
{
    int rc = -ENOBUFS;
    struct llc_sock *llc = llc_sk(sk);
    struct sk_buff *nskb = llc_alloc_frame(sk, llc->dev, LLC_PDU_TYPE_S, 0);

    if (nskb) {
        struct llc_sap *sap = llc->sap;

        llc_pdu_header_init(nskb, LLC_PDU_TYPE_S, sap->laddr.lsap,
                    llc->daddr.lsap, LLC_PDU_RSP);
        llc_pdu_init_as_rnr_rsp(nskb, 0, llc->vR);
        rc = llc_mac_hdr_init(nskb, llc->dev->dev_addr, llc->daddr.mac);
        if (unlikely(rc))
            goto free;
        llc_conn_send_pdu(sk, nskb);
    }
out:
    return rc;
free:
    kfree_skb(nskb);
    goto out;
}

int llc_conn_ac_set_remote_busy(struct sock *sk, struct sk_buff *skb)
{
    struct llc_sock *llc = llc_sk(sk);

    if (!llc->remote_busy_flag) {
        llc->remote_busy_flag = 1;
        mod_timer(&llc->busy_state_timer.timer,
             jiffies + llc->busy_state_timer.expire);
    }
    return 0;
}

int llc_conn_ac_opt_send_rnr_xxx_x_set_0(struct sock *sk, struct sk_buff *skb)
{
    int rc = -ENOBUFS;
    struct llc_sock *llc = llc_sk(sk);
    struct sk_buff *nskb = llc_alloc_frame(sk, llc->dev, LLC_PDU_TYPE_S, 0);

    if (nskb) {
        struct llc_sap *sap = llc->sap;

        llc_pdu_header_init(nskb, LLC_PDU_TYPE_S, sap->laddr.lsap,
                    llc->daddr.lsap, LLC_PDU_RSP);
        llc_pdu_init_as_rnr_rsp(nskb, 0, llc->vR);
        rc = llc_mac_hdr_init(nskb, llc->dev->dev_addr, llc->daddr.mac);
        if (unlikely(rc))
            goto free;
        llc_conn_send_pdu(sk, nskb);
    }
out:
    return rc;
free:
    kfree_skb(nskb);
    goto out;
}

int llc_conn_ac_send_rr_cmd_p_set_1(struct sock *sk, struct sk_buff *skb)
{
    int rc = -ENOBUFS;
    struct llc_sock *llc = llc_sk(sk);
    struct sk_buff *nskb = llc_alloc_frame(sk, llc->dev, LLC_PDU_TYPE_S, 0);

    if (nskb) {
        struct llc_sap *sap = llc->sap;

        llc_pdu_header_init(nskb, LLC_PDU_TYPE_S, sap->laddr.lsap,
                    llc->daddr.lsap, LLC_PDU_CMD);
        llc_pdu_init_as_rr_cmd(nskb, 1, llc->vR);
        rc = llc_mac_hdr_init(nskb, llc->dev->dev_addr, llc->daddr.mac);
        if (unlikely(rc))
            goto free;
        llc_conn_send_pdu(sk, nskb);
    }
out:
    return rc;
free:
    kfree_skb(nskb);
    goto out;
}

int llc_conn_ac_send_rr_rsp_f_set_1(struct sock *sk, struct sk_buff *skb)
{
    int rc = -ENOBUFS;
    struct llc_sock *llc = llc_sk(sk);
    struct sk_buff *nskb = llc_alloc_frame(sk, llc->dev, LLC_PDU_TYPE_S, 0);

    if (nskb) {
        struct llc_sap *sap = llc->sap;
        u8 f_bit = 1;

        llc_pdu_header_init(nskb, LLC_PDU_TYPE_S, sap->laddr.lsap,
                    llc->daddr.lsap, LLC_PDU_RSP);
        llc_pdu_init_as_rr_rsp(nskb, f_bit, llc->vR);
        rc = llc_mac_hdr_init(nskb, llc->dev->dev_addr, llc->daddr.mac);
        if (unlikely(rc))
            goto free;
        llc_conn_send_pdu(sk, nskb);
    }
out:
    return rc;
free:
    kfree_skb(nskb);
    goto out;
}

int llc_conn_ac_send_ack_rsp_f_set_1(struct sock *sk, struct sk_buff *skb)
{
    int rc = -ENOBUFS;
    struct llc_sock *llc = llc_sk(sk);
    struct sk_buff *nskb = llc_alloc_frame(sk, llc->dev, LLC_PDU_TYPE_S, 0);

    if (nskb) {
        struct llc_sap *sap = llc->sap;

        llc_pdu_header_init(nskb, LLC_PDU_TYPE_S, sap->laddr.lsap,
                    llc->daddr.lsap, LLC_PDU_RSP);
        llc_pdu_init_as_rr_rsp(nskb, 1, llc->vR);
        rc = llc_mac_hdr_init(nskb, llc->dev->dev_addr, llc->daddr.mac);
        if (unlikely(rc))
            goto free;
        llc_conn_send_pdu(sk, nskb);
    }
out:
    return rc;
free:
    kfree_skb(nskb);
    goto out;
}

int llc_conn_ac_send_rr_xxx_x_set_0(struct sock *sk, struct sk_buff *skb)
{
    int rc = -ENOBUFS;
    struct llc_sock *llc = llc_sk(sk);
    struct sk_buff *nskb = llc_alloc_frame(sk, llc->dev, LLC_PDU_TYPE_S, 0);

    if (nskb) {
        struct llc_sap *sap = llc->sap;

        llc_pdu_header_init(nskb, LLC_PDU_TYPE_S, sap->laddr.lsap,
                    llc->daddr.lsap, LLC_PDU_RSP);
        llc_pdu_init_as_rr_rsp(nskb, 0, llc->vR);
        rc = llc_mac_hdr_init(nskb, llc->dev->dev_addr, llc->daddr.mac);
        if (unlikely(rc))
            goto free;
        llc_conn_send_pdu(sk, nskb);
    }
out:
    return rc;
free:
    kfree_skb(nskb);
    goto out;
}

int llc_conn_ac_send_ack_xxx_x_set_0(struct sock *sk, struct sk_buff *skb)
{
    int rc = -ENOBUFS;
    struct llc_sock *llc = llc_sk(sk);
    struct sk_buff *nskb = llc_alloc_frame(sk, llc->dev, LLC_PDU_TYPE_S, 0);

    if (nskb) {
        struct llc_sap *sap = llc->sap;

        llc_pdu_header_init(nskb, LLC_PDU_TYPE_S, sap->laddr.lsap,
                    llc->daddr.lsap, LLC_PDU_RSP);
        llc_pdu_init_as_rr_rsp(nskb, 0, llc->vR);
        rc = llc_mac_hdr_init(nskb, llc->dev->dev_addr, llc->daddr.mac);
        if (unlikely(rc))
            goto free;
        llc_conn_send_pdu(sk, nskb);
    }
out:
    return rc;
free:
    kfree_skb(nskb);
    goto out;
}

void llc_conn_set_p_flag(struct sock *sk, u8 value)
{
    int state_changed = llc_sk(sk)->p_flag && !value;

    llc_sk(sk)->p_flag = value;

    if (state_changed)
        sk->sk_state_change(sk);
}

int llc_conn_ac_send_sabme_cmd_p_set_x(struct sock *sk, struct sk_buff *skb)
{
    int rc = -ENOBUFS;
    struct llc_sock *llc = llc_sk(sk);
    struct sk_buff *nskb = llc_alloc_frame(sk, llc->dev, LLC_PDU_TYPE_U, 0);

    if (nskb) {
        struct llc_sap *sap = llc->sap;
        u8 *dmac = llc->daddr.mac;

        if (llc->dev->flags & IFF_LOOPBACK)
            dmac = llc->dev->dev_addr;
        llc_pdu_header_init(nskb, LLC_PDU_TYPE_U, sap->laddr.lsap,
                    llc->daddr.lsap, LLC_PDU_CMD);
        llc_pdu_init_as_sabme_cmd(nskb, 1);
        rc = llc_mac_hdr_init(nskb, llc->dev->dev_addr, dmac);
        if (unlikely(rc))
            goto free;
        llc_conn_send_pdu(sk, nskb);
        llc_conn_set_p_flag(sk, 1);
    }
out:
    return rc;
free:
    kfree_skb(nskb);
    goto out;
}

int llc_conn_ac_send_ua_rsp_f_set_p(struct sock *sk, struct sk_buff *skb)
{
    u8 f_bit;
    int rc = -ENOBUFS;
    struct llc_sock *llc = llc_sk(sk);
    struct sk_buff *nskb = llc_alloc_frame(sk, llc->dev, LLC_PDU_TYPE_U, 0);

    llc_pdu_decode_pf_bit(skb, &f_bit);
    if (nskb) {
        struct llc_sap *sap = llc->sap;

        nskb->dev = llc->dev;
        llc_pdu_header_init(nskb, LLC_PDU_TYPE_U, sap->laddr.lsap,
                    llc->daddr.lsap, LLC_PDU_RSP);
        llc_pdu_init_as_ua_rsp(nskb, f_bit);
        rc = llc_mac_hdr_init(nskb, llc->dev->dev_addr, llc->daddr.mac);
        if (unlikely(rc))
            goto free;
        llc_conn_send_pdu(sk, nskb);
    }
out:
    return rc;
free:
    kfree_skb(nskb);
    goto out;
}

int llc_conn_ac_set_s_flag_0(struct sock *sk, struct sk_buff *skb)
{
    llc_sk(sk)->s_flag = 0;
    return 0;
}

int llc_conn_ac_set_s_flag_1(struct sock *sk, struct sk_buff *skb)
{
    llc_sk(sk)->s_flag = 1;
    return 0;
}

int llc_conn_ac_start_p_timer(struct sock *sk, struct sk_buff *skb)
{
    struct llc_sock *llc = llc_sk(sk);

    llc_conn_set_p_flag(sk, 1);
    mod_timer(&llc->pf_cycle_timer.timer,
          jiffies + llc->pf_cycle_timer.expire);
    return 0;
}

int llc_conn_ac_send_ack_if_needed(struct sock *sk, struct sk_buff *skb)
{
    u8 pf_bit;
    struct llc_sock *llc = llc_sk(sk);

    llc_pdu_decode_pf_bit(skb, &pf_bit);
    llc->ack_pf |= pf_bit & 1;
    if (!llc->ack_must_be_send) {
        llc->first_pdu_Ns = llc->vR;
        llc->ack_must_be_send = 1;
        llc->ack_pf = pf_bit & 1;
    }
    if (((llc->vR - llc->first_pdu_Ns + 1 + LLC_2_SEQ_NBR_MODULO)
            % LLC_2_SEQ_NBR_MODULO) >= llc->npta) {
        llc_conn_ac_send_rr_rsp_f_set_ackpf(sk, skb);
        llc->ack_must_be_send   = 0;
        llc->ack_pf     = 0;
        llc_conn_ac_inc_npta_value(sk, skb);
    }
    return 0;
}

int llc_conn_ac_rst_sendack_flag(struct sock *sk, struct sk_buff *skb)
{
    llc_sk(sk)->ack_must_be_send = llc_sk(sk)->ack_pf = 0;
    return 0;
}

static int llc_conn_ac_send_i_rsp_f_set_ackpf(struct sock *sk,
                          struct sk_buff *skb)
{
    int rc;
    struct llc_sock *llc = llc_sk(sk);
    struct llc_sap *sap = llc->sap;

    llc_pdu_header_init(skb, LLC_PDU_TYPE_I, sap->laddr.lsap,
                llc->daddr.lsap, LLC_PDU_RSP);
    llc_pdu_init_as_i_cmd(skb, llc->ack_pf, llc->vS, llc->vR);
    rc = llc_mac_hdr_init(skb, llc->dev->dev_addr, llc->daddr.mac);
    if (likely(!rc)) {
        llc_conn_send_pdu(sk, skb);
        llc_conn_ac_inc_vs_by_1(sk, skb);
    }
    return rc;
}

int llc_conn_ac_send_i_as_ack(struct sock *sk, struct sk_buff *skb)
{
    struct llc_sock *llc = llc_sk(sk);

    if (llc->ack_must_be_send) {
        llc_conn_ac_send_i_rsp_f_set_ackpf(sk, skb);
        llc->ack_must_be_send = 0 ;
        llc->ack_pf = 0;
    } else
        llc_conn_ac_send_i_cmd_p_set_0(sk, skb);
    return 0;
}

static int llc_conn_ac_send_rr_rsp_f_set_ackpf(struct sock *sk,
                           struct sk_buff *skb)
{
    int rc = -ENOBUFS;
    struct llc_sock *llc = llc_sk(sk);
    struct sk_buff *nskb = llc_alloc_frame(sk, llc->dev, LLC_PDU_TYPE_S, 0);

    if (nskb) {
        struct llc_sap *sap = llc->sap;

        llc_pdu_header_init(nskb, LLC_PDU_TYPE_S, sap->laddr.lsap,
                    llc->daddr.lsap, LLC_PDU_RSP);
        llc_pdu_init_as_rr_rsp(nskb, llc->ack_pf, llc->vR);
        rc = llc_mac_hdr_init(nskb, llc->dev->dev_addr, llc->daddr.mac);
        if (unlikely(rc))
            goto free;
        llc_conn_send_pdu(sk, nskb);
    }
out:
    return rc;
free:
    kfree_skb(nskb);
    goto out;
}

static int llc_conn_ac_inc_npta_value(struct sock *sk, struct sk_buff *skb)
{
    struct llc_sock *llc = llc_sk(sk);

    if (!llc->inc_cntr) {
        llc->dec_step = 0;
        llc->dec_cntr = llc->inc_cntr = 2;
        ++llc->npta;
        if (llc->npta > (u8) ~LLC_2_SEQ_NBR_MODULO)
            llc->npta = (u8) ~LLC_2_SEQ_NBR_MODULO;
    } else
        --llc->inc_cntr;
    return 0;
}

int llc_conn_ac_adjust_npta_by_rr(struct sock *sk, struct sk_buff *skb)
{
    struct llc_sock *llc = llc_sk(sk);

    if (!llc->connect_step && !llc->remote_busy_flag) {
        if (!llc->dec_step) {
            if (!llc->dec_cntr) {
                llc->inc_cntr = llc->dec_cntr = 2;
                if (llc->npta > 0)
                    llc->npta = llc->npta - 1;
            } else
                llc->dec_cntr -=1;
        }
    } else
        llc->connect_step = 0 ;
    return 0;
}

int llc_conn_ac_adjust_npta_by_rnr(struct sock *sk, struct sk_buff *skb)
{
    struct llc_sock *llc = llc_sk(sk);

    if (llc->remote_busy_flag)
        if (!llc->dec_step) {
            if (!llc->dec_cntr) {
                llc->inc_cntr = llc->dec_cntr = 2;
                if (llc->npta > 0)
                    --llc->npta;
            } else
                --llc->dec_cntr;
        }
    return 0;
}

int llc_conn_ac_dec_tx_win_size(struct sock *sk, struct sk_buff *skb)
{
    struct llc_sock *llc = llc_sk(sk);
    u8 unacked_pdu = skb_queue_len(&llc->pdu_unack_q);

    if (llc->k - unacked_pdu < 1)
        llc->k = 1;
    else
        llc->k -= unacked_pdu;
    return 0;
}

int llc_conn_ac_inc_tx_win_size(struct sock *sk, struct sk_buff *skb)
{
    struct llc_sock *llc = llc_sk(sk);

    llc->k += 1;
    if (llc->k > (u8) ~LLC_2_SEQ_NBR_MODULO)
        llc->k = (u8) ~LLC_2_SEQ_NBR_MODULO;
    return 0;
}

int llc_conn_ac_stop_all_timers(struct sock *sk, struct sk_buff *skb)
{
    struct llc_sock *llc = llc_sk(sk);

    del_timer(&llc->pf_cycle_timer.timer);
    del_timer(&llc->ack_timer.timer);
    del_timer(&llc->rej_sent_timer.timer);
    del_timer(&llc->busy_state_timer.timer);
    llc->ack_must_be_send = 0;
    llc->ack_pf = 0;
    return 0;
}

int llc_conn_ac_stop_other_timers(struct sock *sk, struct sk_buff *skb)
{
    struct llc_sock *llc = llc_sk(sk);

    del_timer(&llc->rej_sent_timer.timer);
    del_timer(&llc->pf_cycle_timer.timer);
    del_timer(&llc->busy_state_timer.timer);
    llc->ack_must_be_send = 0;
    llc->ack_pf = 0;
    return 0;
}

int llc_conn_ac_start_ack_timer(struct sock *sk, struct sk_buff *skb)
{
    struct llc_sock *llc = llc_sk(sk);

    mod_timer(&llc->ack_timer.timer, jiffies + llc->ack_timer.expire);
    return 0;
}

int llc_conn_ac_start_rej_timer(struct sock *sk, struct sk_buff *skb)
{
    struct llc_sock *llc = llc_sk(sk);

    mod_timer(&llc->rej_sent_timer.timer,
          jiffies + llc->rej_sent_timer.expire);
    return 0;
}

int llc_conn_ac_start_ack_tmr_if_not_running(struct sock *sk,
                         struct sk_buff *skb)
{
    struct llc_sock *llc = llc_sk(sk);

    if (!timer_pending(&llc->ack_timer.timer))
        mod_timer(&llc->ack_timer.timer,
              jiffies + llc->ack_timer.expire);
    return 0;
}

int llc_conn_ac_stop_ack_timer(struct sock *sk, struct sk_buff *skb)
{
    del_timer(&llc_sk(sk)->ack_timer.timer);
    return 0;
}

int llc_conn_ac_stop_p_timer(struct sock *sk, struct sk_buff *skb)
{
    struct llc_sock *llc = llc_sk(sk);

    del_timer(&llc->pf_cycle_timer.timer);
    llc_conn_set_p_flag(sk, 0);
    return 0;
}

int llc_conn_ac_stop_rej_timer(struct sock *sk, struct sk_buff *skb)
{
    del_timer(&llc_sk(sk)->rej_sent_timer.timer);
    return 0;
}

int llc_conn_ac_upd_nr_received(struct sock *sk, struct sk_buff *skb)
{
    int acked;
    u16 unacked = 0;
    struct llc_pdu_sn *pdu = llc_pdu_sn_hdr(skb);
    struct llc_sock *llc = llc_sk(sk);

    llc->last_nr = PDU_SUPV_GET_Nr(pdu);
    acked = llc_conn_remove_acked_pdus(sk, llc->last_nr, &unacked);
    /* On loopback we don't queue I frames in unack_pdu_q queue. */
    if (acked > 0 || (llc->dev->flags & IFF_LOOPBACK)) {
        llc->retry_count = 0;
        del_timer(&llc->ack_timer.timer);
        if (llc->failed_data_req) {
            /* already, we did not accept data from upper layer
             * (tx_window full or unacceptable state). Now, we
             * can send data and must inform to upper layer.
             */
            llc->failed_data_req = 0;
            llc_conn_ac_data_confirm(sk, skb);
        }
        if (unacked)
            mod_timer(&llc->ack_timer.timer,
                  jiffies + llc->ack_timer.expire);
    } else if (llc->failed_data_req) {
        u8 f_bit;

        llc_pdu_decode_pf_bit(skb, &f_bit);
        if (f_bit == 1) {
            llc->failed_data_req = 0;
            llc_conn_ac_data_confirm(sk, skb);
        }
    }
    return 0;
}

int llc_conn_ac_upd_p_flag(struct sock *sk, struct sk_buff *skb)
{
    struct llc_pdu_sn *pdu = llc_pdu_sn_hdr(skb);

    if (LLC_PDU_IS_RSP(pdu)) {
        u8 f_bit;

        llc_pdu_decode_pf_bit(skb, &f_bit);
        if (f_bit) {
            llc_conn_set_p_flag(sk, 0);
            llc_conn_ac_stop_p_timer(sk, skb);
        }
    }
    return 0;
}

int llc_conn_ac_set_data_flag_2(struct sock *sk, struct sk_buff *skb)
{
    llc_sk(sk)->data_flag = 2;
    return 0;
}

int llc_conn_ac_set_data_flag_0(struct sock *sk, struct sk_buff *skb)
{
    llc_sk(sk)->data_flag = 0;
    return 0;
}

int llc_conn_ac_set_data_flag_1(struct sock *sk, struct sk_buff *skb)
{
    llc_sk(sk)->data_flag = 1;
    return 0;
}

int llc_conn_ac_set_data_flag_1_if_data_flag_eq_0(struct sock *sk,
                          struct sk_buff *skb)
{
    if (!llc_sk(sk)->data_flag)
        llc_sk(sk)->data_flag = 1;
    return 0;
}

int llc_conn_ac_set_p_flag_0(struct sock *sk, struct sk_buff *skb)
{
    llc_conn_set_p_flag(sk, 0);
    return 0;
}

static int llc_conn_ac_set_p_flag_1(struct sock *sk, struct sk_buff *skb)
{
    llc_conn_set_p_flag(sk, 1);
    return 0;
}

int llc_conn_ac_set_remote_busy_0(struct sock *sk, struct sk_buff *skb)
{
    llc_sk(sk)->remote_busy_flag = 0;
    return 0;
}

int llc_conn_ac_set_cause_flag_0(struct sock *sk, struct sk_buff *skb)
{
    llc_sk(sk)->cause_flag = 0;
    return 0;
}

int llc_conn_ac_set_cause_flag_1(struct sock *sk, struct sk_buff *skb)
{
    llc_sk(sk)->cause_flag = 1;
    return 0;
}

int llc_conn_ac_set_retry_cnt_0(struct sock *sk, struct sk_buff *skb)
{
    llc_sk(sk)->retry_count = 0;
    return 0;
}

int llc_conn_ac_inc_retry_cnt_by_1(struct sock *sk, struct sk_buff *skb)
{
    llc_sk(sk)->retry_count++;
    return 0;
}

int llc_conn_ac_set_vr_0(struct sock *sk, struct sk_buff *skb)
{
    llc_sk(sk)->vR = 0;
    return 0;
}

int llc_conn_ac_inc_vr_by_1(struct sock *sk, struct sk_buff *skb)
{
    llc_sk(sk)->vR = PDU_GET_NEXT_Vr(llc_sk(sk)->vR);
    return 0;
}

int llc_conn_ac_set_vs_0(struct sock *sk, struct sk_buff *skb)
{
    llc_sk(sk)->vS = 0;
    return 0;
}

int llc_conn_ac_set_vs_nr(struct sock *sk, struct sk_buff *skb)
{
    llc_sk(sk)->vS = llc_sk(sk)->last_nr;
    return 0;
}

static int llc_conn_ac_inc_vs_by_1(struct sock *sk, struct sk_buff *skb)
{
    llc_sk(sk)->vS = (llc_sk(sk)->vS + 1) % LLC_2_SEQ_NBR_MODULO;
    return 0;
}

static void llc_conn_tmr_common_cb(unsigned long timeout_data, u8 type)
{
    struct sock *sk = (struct sock *)timeout_data;
    struct sk_buff *skb = alloc_skb(0, GFP_ATOMIC);

    bh_lock_sock(sk);
    if (skb) {
        struct llc_conn_state_ev *ev = llc_conn_ev(skb);

        skb_set_owner_r(skb, sk);
        ev->type = type;
        llc_process_tmr_ev(sk, skb);
    }
    bh_unlock_sock(sk);
}

void llc_conn_pf_cycle_tmr_cb(unsigned long timeout_data)
{
    llc_conn_tmr_common_cb(timeout_data, LLC_CONN_EV_TYPE_P_TMR);
}

void llc_conn_busy_tmr_cb(unsigned long timeout_data)
{
    llc_conn_tmr_common_cb(timeout_data, LLC_CONN_EV_TYPE_BUSY_TMR);
}

void llc_conn_ack_tmr_cb(unsigned long timeout_data)
{
    llc_conn_tmr_common_cb(timeout_data, LLC_CONN_EV_TYPE_ACK_TMR);
}

void llc_conn_rej_tmr_cb(unsigned long timeout_data)
{
    llc_conn_tmr_common_cb(timeout_data, LLC_CONN_EV_TYPE_REJ_TMR);
}

int llc_conn_ac_rst_vs(struct sock *sk, struct sk_buff *skb)
{
    llc_sk(sk)->X = llc_sk(sk)->vS;
    llc_conn_ac_set_vs_nr(sk, skb);
    return 0;
}

int llc_conn_ac_upd_vs(struct sock *sk, struct sk_buff *skb)
{
    struct llc_pdu_sn *pdu = llc_pdu_sn_hdr(skb);
    u8 nr = PDU_SUPV_GET_Nr(pdu);

    if (llc_circular_between(llc_sk(sk)->vS, nr, llc_sk(sk)->X))
        llc_conn_ac_set_vs_nr(sk, skb);
    return 0;
}

/*
 * Non-standard actions; these not contained in IEEE specification; for
 * our own usage
 */
int llc_conn_disc(struct sock *sk, struct sk_buff *skb)
{
    /* FIXME: this thing seems to want to die */
    return 0;
}

int llc_conn_reset(struct sock *sk, struct sk_buff *skb)
{
    llc_sk_reset(sk);
    return 0;
}

u8 llc_circular_between(u8 a, u8 b, u8 c)
{
    b = b - a;
    c = c - a;
    return b <= c;
}

static void llc_process_tmr_ev(struct sock *sk, struct sk_buff *skb)
{
    if (llc_sk(sk)->state == LLC_CONN_OUT_OF_SVC) {
        printk(KERN_WARNING "%s: timer called on closed connection\n",
               __func__);
        kfree_skb(skb);
    } else {
        if (!sock_owned_by_user(sk))
            llc_conn_state_process(sk, skb);
        else {
            llc_set_backlog_type(skb, LLC_EVENT);
            __sk_add_backlog(sk, skb);
        }
    }
}