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root/net/lapb/lapb_in.c

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DEFINITIONS

This source file includes following definitions.
  1. lapb_state0_machine
  2. lapb_state1_machine
  3. lapb_state2_machine
  4. lapb_state3_machine
  5. lapb_state4_machine
  6. lapb_data_input

/*
 *      LAPB release 002
 *
 *      This code REQUIRES 2.1.15 or higher/ NET3.038
 *
 *      This module:
 *              This module 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.
 *
 *      History
 *      LAPB 001        Jonathan Naulor Started Coding
 *      LAPB 002        Jonathan Naylor New timer architecture.
 *      2000-10-29      Henner Eisen    lapb_data_indication() return status.
 */

#include <linux/errno.h>
#include <linux/types.h>
#include <linux/socket.h>
#include <linux/in.h>
#include <linux/kernel.h>
#include <linux/timer.h>
#include <linux/string.h>
#include <linux/sockios.h>
#include <linux/net.h>
#include <linux/inet.h>
#include <linux/netdevice.h>
#include <linux/skbuff.h>
#include <net/sock.h>
#include <asm/uaccess.h>
#include <asm/system.h>
#include <linux/fcntl.h>
#include <linux/mm.h>
#include <linux/interrupt.h>
#include <net/lapb.h>

/*
 *      State machine for state 0, Disconnected State.
 *      The handling of the timer(s) is in file lapb_timer.c.
 */
static void lapb_state0_machine(struct lapb_cb *lapb, struct sk_buff *skb,
                                struct lapb_frame *frame)
{
        switch (frame->type) {
                case LAPB_SABM:
#if LAPB_DEBUG > 1
                        printk(KERN_DEBUG "lapb: (%p) S0 RX SABM(%d)\n",
                               lapb->dev, frame->pf);
#endif
                        if (lapb->mode & LAPB_EXTENDED) {
#if LAPB_DEBUG > 1
                                printk(KERN_DEBUG "lapb: (%p) S0 TX DM(%d)\n",
                                       lapb->dev, frame->pf);
#endif
                                lapb_send_control(lapb, LAPB_DM, frame->pf,
                                                  LAPB_RESPONSE);
                        } else {
#if LAPB_DEBUG > 1
                                printk(KERN_DEBUG "lapb: (%p) S0 TX UA(%d)\n",
                                       lapb->dev, frame->pf);
#endif
#if LAPB_DEBUG > 0
                                printk(KERN_DEBUG "lapb: (%p) S0 -> S3\n",
                                       lapb->dev);
#endif
                                lapb_send_control(lapb, LAPB_UA, frame->pf,
                                                  LAPB_RESPONSE);
                                lapb_stop_t1timer(lapb);
                                lapb_stop_t2timer(lapb);
                                lapb->state     = LAPB_STATE_3;
                                lapb->condition = 0x00;
                                lapb->n2count   = 0;
                                lapb->vs        = 0;
                                lapb->vr        = 0;
                                lapb->va        = 0;
                                lapb_connect_indication(lapb, LAPB_OK);
                        }
                        break;

                case LAPB_SABME:
#if LAPB_DEBUG > 1
                        printk(KERN_DEBUG "lapb: (%p) S0 RX SABME(%d)\n",
                               lapb->dev, frame->pf);
#endif
                        if (lapb->mode & LAPB_EXTENDED) {
#if LAPB_DEBUG > 1
                                printk(KERN_DEBUG "lapb: (%p) S0 TX UA(%d)\n",
                                       lapb->dev, frame->pf);
#endif
#if LAPB_DEBUG > 0
                                printk(KERN_DEBUG "lapb: (%p) S0 -> S3\n",
                                       lapb->dev);
#endif
                                lapb_send_control(lapb, LAPB_UA, frame->pf,
                                                  LAPB_RESPONSE);
                                lapb_stop_t1timer(lapb);
                                lapb_stop_t2timer(lapb);
                                lapb->state     = LAPB_STATE_3;
                                lapb->condition = 0x00;
                                lapb->n2count   = 0;
                                lapb->vs        = 0;
                                lapb->vr        = 0;
                                lapb->va        = 0;
                                lapb_connect_indication(lapb, LAPB_OK);
                        } else {
#if LAPB_DEBUG > 1
                                printk(KERN_DEBUG "lapb: (%p) S0 TX DM(%d)\n",
                                       lapb->dev, frame->pf);
#endif
                                lapb_send_control(lapb, LAPB_DM, frame->pf,
                                                  LAPB_RESPONSE);
                        }
                        break;

                case LAPB_DISC:
#if LAPB_DEBUG > 1
                        printk(KERN_DEBUG "lapb: (%p) S0 RX DISC(%d)\n",
                               lapb->dev, frame->pf);
                        printk(KERN_DEBUG "lapb: (%p) S0 TX UA(%d)\n",
                               lapb->dev, frame->pf);
#endif
                        lapb_send_control(lapb, LAPB_UA, frame->pf,
                                          LAPB_RESPONSE);
                        break;

                default:
                        break;
        }

        kfree_skb(skb);
}

/*
 *      State machine for state 1, Awaiting Connection State.
 *      The handling of the timer(s) is in file lapb_timer.c.
 */
static void lapb_state1_machine(struct lapb_cb *lapb, struct sk_buff *skb,
                                struct lapb_frame *frame)
{
        switch (frame->type) {
                case LAPB_SABM:
#if LAPB_DEBUG > 1
                        printk(KERN_DEBUG "lapb: (%p) S1 RX SABM(%d)\n",
                               lapb->dev, frame->pf);
#endif
                        if (lapb->mode & LAPB_EXTENDED) {
#if LAPB_DEBUG > 1
                                printk(KERN_DEBUG "lapb: (%p) S1 TX DM(%d)\n",
                                       lapb->dev, frame->pf);
#endif
                                lapb_send_control(lapb, LAPB_DM, frame->pf,
                                                  LAPB_RESPONSE);
                        } else {
#if LAPB_DEBUG > 1
                                printk(KERN_DEBUG "lapb: (%p) S1 TX UA(%d)\n",
                                       lapb->dev, frame->pf);
#endif
                                lapb_send_control(lapb, LAPB_UA, frame->pf,
                                                  LAPB_RESPONSE);
                        }
                        break;

                case LAPB_SABME:
#if LAPB_DEBUG > 1
                        printk(KERN_DEBUG "lapb: (%p) S1 RX SABME(%d)\n",
                               lapb->dev, frame->pf);
#endif
                        if (lapb->mode & LAPB_EXTENDED) {
#if LAPB_DEBUG > 1
                                printk(KERN_DEBUG "lapb: (%p) S1 TX UA(%d)\n",
                                       lapb->dev, frame->pf);
#endif
                                lapb_send_control(lapb, LAPB_UA, frame->pf,
                                                  LAPB_RESPONSE);
                        } else {
#if LAPB_DEBUG > 1
                                printk(KERN_DEBUG "lapb: (%p) S1 TX DM(%d)\n",
                                       lapb->dev, frame->pf);
#endif
                                lapb_send_control(lapb, LAPB_DM, frame->pf,
                                                  LAPB_RESPONSE);
                        }
                        break;

                case LAPB_DISC:
#if LAPB_DEBUG > 1
                        printk(KERN_DEBUG "lapb: (%p) S1 RX DISC(%d)\n",
                               lapb->dev, frame->pf);
                        printk(KERN_DEBUG "lapb: (%p) S1 TX DM(%d)\n",
                               lapb->dev, frame->pf);
#endif
                        lapb_send_control(lapb, LAPB_DM, frame->pf,
                                          LAPB_RESPONSE);
                        break;

                case LAPB_UA:
#if LAPB_DEBUG > 1
                        printk(KERN_DEBUG "lapb: (%p) S1 RX UA(%d)\n",
                               lapb->dev, frame->pf);
#endif
                        if (frame->pf) {
#if LAPB_DEBUG > 0
                                printk(KERN_DEBUG "lapb: (%p) S1 -> S3\n",
                                       lapb->dev);
#endif
                                lapb_stop_t1timer(lapb);
                                lapb_stop_t2timer(lapb);
                                lapb->state     = LAPB_STATE_3;
                                lapb->condition = 0x00;
                                lapb->n2count   = 0;
                                lapb->vs        = 0;
                                lapb->vr        = 0;
                                lapb->va        = 0;
                                lapb_connect_confirmation(lapb, LAPB_OK);
                        }
                        break;

                case LAPB_DM:
#if LAPB_DEBUG > 1
                        printk(KERN_DEBUG "lapb: (%p) S1 RX DM(%d)\n",
                               lapb->dev, frame->pf);
#endif
                        if (frame->pf) {
#if LAPB_DEBUG > 0
                                printk(KERN_DEBUG "lapb: (%p) S1 -> S0\n",
                                       lapb->dev);
#endif
                                lapb_clear_queues(lapb);
                                lapb->state = LAPB_STATE_0;
                                lapb_start_t1timer(lapb);
                                lapb_stop_t2timer(lapb);
                                lapb_disconnect_indication(lapb, LAPB_REFUSED);
                        }
                        break;
        }

        kfree_skb(skb);
}

/*
 *      State machine for state 2, Awaiting Release State.
 *      The handling of the timer(s) is in file lapb_timer.c
 */
static void lapb_state2_machine(struct lapb_cb *lapb, struct sk_buff *skb,
                                struct lapb_frame *frame)
{
        switch (frame->type) {
                case LAPB_SABM:
                case LAPB_SABME:
#if LAPB_DEBUG > 1
                        printk(KERN_DEBUG "lapb: (%p) S2 RX {SABM,SABME}(%d)\n",
                               lapb->dev, frame->pf);
                        printk(KERN_DEBUG "lapb: (%p) S2 TX DM(%d)\n",
                               lapb->dev, frame->pf);
#endif
                        lapb_send_control(lapb, LAPB_DM, frame->pf,
                                          LAPB_RESPONSE);
                        break;

                case LAPB_DISC:
#if LAPB_DEBUG > 1
                        printk(KERN_DEBUG "lapb: (%p) S2 RX DISC(%d)\n",
                               lapb->dev, frame->pf);
                        printk(KERN_DEBUG "lapb: (%p) S2 TX UA(%d)\n",
                               lapb->dev, frame->pf);
#endif
                        lapb_send_control(lapb, LAPB_UA, frame->pf,
                                          LAPB_RESPONSE);
                        break;

                case LAPB_UA:
#if LAPB_DEBUG > 1
                        printk(KERN_DEBUG "lapb: (%p) S2 RX UA(%d)\n",
                               lapb->dev, frame->pf);
#endif
                        if (frame->pf) {
#if LAPB_DEBUG > 0
                                printk(KERN_DEBUG "lapb: (%p) S2 -> S0\n",
                                       lapb->dev);
#endif
                                lapb->state = LAPB_STATE_0;
                                lapb_start_t1timer(lapb);
                                lapb_stop_t2timer(lapb);
                                lapb_disconnect_confirmation(lapb, LAPB_OK);
                        }
                        break;

                case LAPB_DM:
#if LAPB_DEBUG > 1
                        printk(KERN_DEBUG "lapb: (%p) S2 RX DM(%d)\n",
                               lapb->dev, frame->pf);
#endif
                        if (frame->pf) {
#if LAPB_DEBUG > 0
                                printk(KERN_DEBUG "lapb: (%p) S2 -> S0\n",
                                       lapb->dev);
#endif
                                lapb->state = LAPB_STATE_0;
                                lapb_start_t1timer(lapb);
                                lapb_stop_t2timer(lapb);
                                lapb_disconnect_confirmation(lapb,
                                                             LAPB_NOTCONNECTED);
                        }
                        break;

                case LAPB_I:
                case LAPB_REJ:
                case LAPB_RNR:
                case LAPB_RR:
#if LAPB_DEBUG > 1
                        printk(KERN_DEBUG "lapb: (%p) S2 RX {I,REJ,RNR,RR}"
                               "(%d)\n", lapb->dev, frame->pf);
                        printk(KERN_DEBUG "lapb: (%p) S2 RX DM(%d)\n",
                               lapb->dev, frame->pf);
#endif
                        if (frame->pf)
                                lapb_send_control(lapb, LAPB_DM, frame->pf,
                                                  LAPB_RESPONSE);
                        break;
        }

        kfree_skb(skb);
}

/*
 *      State machine for state 3, Connected State.
 *      The handling of the timer(s) is in file lapb_timer.c
 */
static void lapb_state3_machine(struct lapb_cb *lapb, struct sk_buff *skb,
                                struct lapb_frame *frame)
{
        int queued = 0;
        int modulus = (lapb->mode & LAPB_EXTENDED) ? LAPB_EMODULUS :
                                                     LAPB_SMODULUS;

        switch (frame->type) {
                case LAPB_SABM:
#if LAPB_DEBUG > 1
                        printk(KERN_DEBUG "lapb: (%p) S3 RX SABM(%d)\n",
                               lapb->dev, frame->pf);
#endif
                        if (lapb->mode & LAPB_EXTENDED) {
#if LAPB_DEBUG > 1
                                printk(KERN_DEBUG "lapb: (%p) S3 TX DM(%d)\n",
                                       lapb->dev, frame->pf);
#endif
                                lapb_send_control(lapb, LAPB_DM, frame->pf,
                                                  LAPB_RESPONSE);
                        } else {
#if LAPB_DEBUG > 1
                                printk(KERN_DEBUG "lapb: (%p) S3 TX UA(%d)\n",
                                       lapb->dev, frame->pf);
#endif
                                lapb_send_control(lapb, LAPB_UA, frame->pf,
                                                  LAPB_RESPONSE);
                                lapb_stop_t1timer(lapb);
                                lapb_stop_t2timer(lapb);
                                lapb->condition = 0x00;
                                lapb->n2count   = 0;
                                lapb->vs        = 0;
                                lapb->vr        = 0;
                                lapb->va        = 0;
                                lapb_requeue_frames(lapb);
                        }
                        break;

                case LAPB_SABME:
#if LAPB_DEBUG > 1
                        printk(KERN_DEBUG "lapb: (%p) S3 RX SABME(%d)\n",
                               lapb->dev, frame->pf);
#endif
                        if (lapb->mode & LAPB_EXTENDED) {
#if LAPB_DEBUG > 1
                                printk(KERN_DEBUG "lapb: (%p) S3 TX UA(%d)\n",
                                       lapb->dev, frame->pf);
#endif
                                lapb_send_control(lapb, LAPB_UA, frame->pf,
                                                  LAPB_RESPONSE);
                                lapb_stop_t1timer(lapb);
                                lapb_stop_t2timer(lapb);
                                lapb->condition = 0x00;
                                lapb->n2count   = 0;
                                lapb->vs        = 0;
                                lapb->vr        = 0;
                                lapb->va        = 0;
                                lapb_requeue_frames(lapb);
                        } else {
#if LAPB_DEBUG > 1
                                printk(KERN_DEBUG "lapb: (%p) S3 TX DM(%d)\n",
                                       lapb->dev, frame->pf);
#endif
                                lapb_send_control(lapb, LAPB_DM, frame->pf,
                                                  LAPB_RESPONSE);
                        }
                        break;

                case LAPB_DISC:
#if LAPB_DEBUG > 1
                        printk(KERN_DEBUG "lapb: (%p) S3 RX DISC(%d)\n",
                               lapb->dev, frame->pf);
#endif
#if LAPB_DEBUG > 0
                        printk(KERN_DEBUG "lapb: (%p) S3 -> S0\n",
                               lapb->dev);
#endif
                        lapb_clear_queues(lapb);
                        lapb_send_control(lapb, LAPB_UA, frame->pf,
                                          LAPB_RESPONSE);
                        lapb_start_t1timer(lapb);
                        lapb_stop_t2timer(lapb);
                        lapb->state = LAPB_STATE_0;
                        lapb_disconnect_indication(lapb, LAPB_OK);
                        break;

                case LAPB_DM:
#if LAPB_DEBUG > 1
                        printk(KERN_DEBUG "lapb: (%p) S3 RX DM(%d)\n",
                               lapb->dev, frame->pf);
#endif
#if LAPB_DEBUG > 0
                        printk(KERN_DEBUG "lapb: (%p) S3 -> S0\n",
                               lapb->dev);
#endif
                        lapb_clear_queues(lapb);
                        lapb->state = LAPB_STATE_0;
                        lapb_start_t1timer(lapb);
                        lapb_stop_t2timer(lapb);
                        lapb_disconnect_indication(lapb, LAPB_NOTCONNECTED);
                        break;

                case LAPB_RNR:
#if LAPB_DEBUG > 1
                        printk(KERN_DEBUG "lapb: (%p) S3 RX RNR(%d) R%d\n",
                               lapb->dev, frame->pf, frame->nr);
#endif
                        lapb->condition |= LAPB_PEER_RX_BUSY_CONDITION;
                        lapb_check_need_response(lapb, frame->cr, frame->pf);
                        if (lapb_validate_nr(lapb, frame->nr)) {
                                lapb_check_iframes_acked(lapb, frame->nr);
                        } else {
                                lapb->frmr_data = *frame;
                                lapb->frmr_type = LAPB_FRMR_Z;
                                lapb_transmit_frmr(lapb);
#if LAPB_DEBUG > 0
                                printk(KERN_DEBUG "lapb: (%p) S3 -> S4\n",
                                       lapb->dev);
#endif
                                lapb_start_t1timer(lapb);
                                lapb_stop_t2timer(lapb);
                                lapb->state   = LAPB_STATE_4;
                                lapb->n2count = 0;
                        }
                        break;

                case LAPB_RR:
#if LAPB_DEBUG > 1
                        printk(KERN_DEBUG "lapb: (%p) S3 RX RR(%d) R%d\n",
                               lapb->dev, frame->pf, frame->nr);
#endif
                        lapb->condition &= ~LAPB_PEER_RX_BUSY_CONDITION;
                        lapb_check_need_response(lapb, frame->cr, frame->pf);
                        if (lapb_validate_nr(lapb, frame->nr)) {
                                lapb_check_iframes_acked(lapb, frame->nr);
                        } else {
                                lapb->frmr_data = *frame;
                                lapb->frmr_type = LAPB_FRMR_Z;
                                lapb_transmit_frmr(lapb);
#if LAPB_DEBUG > 0
                                printk(KERN_DEBUG "lapb: (%p) S3 -> S4\n",
                                       lapb->dev);
#endif
                                lapb_start_t1timer(lapb);
                                lapb_stop_t2timer(lapb);
                                lapb->state   = LAPB_STATE_4;
                                lapb->n2count = 0;
                        }
                        break;

                case LAPB_REJ:
#if LAPB_DEBUG > 1
                        printk(KERN_DEBUG "lapb: (%p) S3 RX REJ(%d) R%d\n",
                               lapb->dev, frame->pf, frame->nr);
#endif
                        lapb->condition &= ~LAPB_PEER_RX_BUSY_CONDITION;
                        lapb_check_need_response(lapb, frame->cr, frame->pf);
                        if (lapb_validate_nr(lapb, frame->nr)) {
                                lapb_frames_acked(lapb, frame->nr);
                                lapb_stop_t1timer(lapb);
                                lapb->n2count = 0;
                                lapb_requeue_frames(lapb);
                        } else {
                                lapb->frmr_data = *frame;
                                lapb->frmr_type = LAPB_FRMR_Z;
                                lapb_transmit_frmr(lapb);
#if LAPB_DEBUG > 0
                                printk(KERN_DEBUG "lapb: (%p) S3 -> S4\n",
                                       lapb->dev);
#endif
                                lapb_start_t1timer(lapb);
                                lapb_stop_t2timer(lapb);
                                lapb->state   = LAPB_STATE_4;
                                lapb->n2count = 0;
                        }
                        break;

                case LAPB_I:
#if LAPB_DEBUG > 1
                        printk(KERN_DEBUG "lapb: (%p) S3 RX I(%d) S%d R%d\n",
                               lapb->dev, frame->pf, frame->ns, frame->nr);
#endif
                        if (!lapb_validate_nr(lapb, frame->nr)) {
                                lapb->frmr_data = *frame;
                                lapb->frmr_type = LAPB_FRMR_Z;
                                lapb_transmit_frmr(lapb);
#if LAPB_DEBUG > 0
                                printk(KERN_DEBUG "lapb: (%p) S3 -> S4\n",
                                       lapb->dev);
#endif
                                lapb_start_t1timer(lapb);
                                lapb_stop_t2timer(lapb);
                                lapb->state   = LAPB_STATE_4;
                                lapb->n2count = 0;
                                break;
                        }
                        if (lapb->condition & LAPB_PEER_RX_BUSY_CONDITION)
                                lapb_frames_acked(lapb, frame->nr);
                        else
                                lapb_check_iframes_acked(lapb, frame->nr);

                        if (frame->ns == lapb->vr) {
                                int cn;
                                cn = lapb_data_indication(lapb, skb);
                                queued = 1;
                                /*
                                 * If upper layer has dropped the frame, we
                                 * basically ignore any further protocol
                                 * processing. This will cause the peer
                                 * to re-transmit the frame later like
                                 * a frame lost on the wire.
                                 */
                                if (cn == NET_RX_DROP) {
                                        printk(KERN_DEBUG
                                               "LAPB: rx congestion\n");
                                        break;
                                }
                                lapb->vr = (lapb->vr + 1) % modulus;
                                lapb->condition &= ~LAPB_REJECT_CONDITION;
                                if (frame->pf)
                                        lapb_enquiry_response(lapb);
                                else {
                                        if (!(lapb->condition &
                                              LAPB_ACK_PENDING_CONDITION)) {
                                                lapb->condition |= LAPB_ACK_PENDING_CONDITION;
                                                lapb_start_t2timer(lapb);
                                        }
                                }
                        } else {
                                if (lapb->condition & LAPB_REJECT_CONDITION) {
                                        if (frame->pf)
                                                lapb_enquiry_response(lapb);
                                } else {
#if LAPB_DEBUG > 1
                                        printk(KERN_DEBUG
                                               "lapb: (%p) S3 TX REJ(%d) R%d\n",
                                               lapb->dev, frame->pf, lapb->vr);
#endif
                                        lapb->condition |= LAPB_REJECT_CONDITION;
                                        lapb_send_control(lapb, LAPB_REJ,
                                                          frame->pf,
                                                          LAPB_RESPONSE);
                                        lapb->condition &= ~LAPB_ACK_PENDING_CONDITION;
                                }
                        }
                        break;

                case LAPB_FRMR:
#if LAPB_DEBUG > 1
                        printk(KERN_DEBUG "lapb: (%p) S3 RX FRMR(%d) %02X "
                               "%02X %02X %02X %02X\n", lapb->dev, frame->pf,
                               skb->data[0], skb->data[1], skb->data[2],
                               skb->data[3], skb->data[4]);
#endif
                        lapb_establish_data_link(lapb);
#if LAPB_DEBUG > 0
                        printk(KERN_DEBUG "lapb: (%p) S3 -> S1\n",
                               lapb->dev);
#endif
                        lapb_requeue_frames(lapb);
                        lapb->state = LAPB_STATE_1;
                        break;

                case LAPB_ILLEGAL:
#if LAPB_DEBUG > 1
                        printk(KERN_DEBUG "lapb: (%p) S3 RX ILLEGAL(%d)\n",
                               lapb->dev, frame->pf);
#endif
                        lapb->frmr_data = *frame;
                        lapb->frmr_type = LAPB_FRMR_W;
                        lapb_transmit_frmr(lapb);
#if LAPB_DEBUG > 0
                        printk(KERN_DEBUG "lapb: (%p) S3 -> S4\n", lapb->dev);
#endif
                        lapb_start_t1timer(lapb);
                        lapb_stop_t2timer(lapb);
                        lapb->state   = LAPB_STATE_4;
                        lapb->n2count = 0;
                        break;
        }

        if (!queued)
                kfree_skb(skb);
}

/*
 *      State machine for state 4, Frame Reject State.
 *      The handling of the timer(s) is in file lapb_timer.c.
 */
static void lapb_state4_machine(struct lapb_cb *lapb, struct sk_buff *skb,
                                struct lapb_frame *frame)
{
        switch (frame->type) {
                case LAPB_SABM:
#if LAPB_DEBUG > 1
                        printk(KERN_DEBUG "lapb: (%p) S4 RX SABM(%d)\n",
                               lapb->dev, frame->pf);
#endif
                        if (lapb->mode & LAPB_EXTENDED) {
#if LAPB_DEBUG > 1
                                printk(KERN_DEBUG "lapb: (%p) S4 TX DM(%d)\n",
                                       lapb->dev, frame->pf);
#endif
                                lapb_send_control(lapb, LAPB_DM, frame->pf,
                                                  LAPB_RESPONSE);
                        } else {
#if LAPB_DEBUG > 1
                                printk(KERN_DEBUG "lapb: (%p) S4 TX UA(%d)\n",
                                       lapb->dev, frame->pf);
#endif
#if LAPB_DEBUG > 0
                                printk(KERN_DEBUG "lapb: (%p) S4 -> S3\n",
                                       lapb->dev);
#endif
                                lapb_send_control(lapb, LAPB_UA, frame->pf,
                                                  LAPB_RESPONSE);
                                lapb_stop_t1timer(lapb);
                                lapb_stop_t2timer(lapb);
                                lapb->state     = LAPB_STATE_3;
                                lapb->condition = 0x00;
                                lapb->n2count   = 0;
                                lapb->vs        = 0;
                                lapb->vr        = 0;
                                lapb->va        = 0;
                                lapb_connect_indication(lapb, LAPB_OK);
                        }
                        break;

                case LAPB_SABME:
#if LAPB_DEBUG > 1
                        printk(KERN_DEBUG "lapb: (%p) S4 RX SABME(%d)\n",
                               lapb->dev, frame->pf);
#endif
                        if (lapb->mode & LAPB_EXTENDED) {
#if LAPB_DEBUG > 1
                                printk(KERN_DEBUG "lapb: (%p) S4 TX UA(%d)\n",
                                       lapb->dev, frame->pf);
#endif
#if LAPB_DEBUG > 0
                                printk(KERN_DEBUG "lapb: (%p) S4 -> S3\n",
                                       lapb->dev);
#endif
                                lapb_send_control(lapb, LAPB_UA, frame->pf,
                                                  LAPB_RESPONSE);
                                lapb_stop_t1timer(lapb);
                                lapb_stop_t2timer(lapb);
                                lapb->state     = LAPB_STATE_3;
                                lapb->condition = 0x00;
                                lapb->n2count   = 0;
                                lapb->vs        = 0;
                                lapb->vr        = 0;
                                lapb->va        = 0;
                                lapb_connect_indication(lapb, LAPB_OK);
                        } else {
#if LAPB_DEBUG > 1
                                printk(KERN_DEBUG "lapb: (%p) S4 TX DM(%d)\n",
                                       lapb->dev, frame->pf);
#endif
                                lapb_send_control(lapb, LAPB_DM, frame->pf,
                                                  LAPB_RESPONSE);
                        }
                        break;
        }

        kfree_skb(skb);
}

/*
 *      Process an incoming LAPB frame
 */
void lapb_data_input(struct lapb_cb *lapb, struct sk_buff *skb)
{
        struct lapb_frame frame;

        if (lapb_decode(lapb, skb, &frame) < 0) {
                kfree_skb(skb);
                return;
        }

        switch (lapb->state) {
        case LAPB_STATE_0:
                lapb_state0_machine(lapb, skb, &frame); break;
        case LAPB_STATE_1:
                lapb_state1_machine(lapb, skb, &frame); break;
        case LAPB_STATE_2:
                lapb_state2_machine(lapb, skb, &frame); break;
        case LAPB_STATE_3:
                lapb_state3_machine(lapb, skb, &frame); break;
        case LAPB_STATE_4:
                lapb_state4_machine(lapb, skb, &frame); break;
        }

        lapb_kick(lapb);
}

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