net/lapb/lapb_in.c - pub/scm/linux/kernel/git/ast/bpf - Git at Google

 // SPDX-License-Identifier: GPL-2.0-or-later
 /*
  *	LAPB release 002
  *
  *	This code REQUIRES 2.1.15 or higher/ NET3.038
  *
  *	History
  *	LAPB 001	Jonathan Naulor	Started Coding
  *	LAPB 002	Jonathan Naylor	New timer architecture.
  *	2000-10-29	Henner Eisen	lapb_data_indication() return status.
  */

 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

 #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 <linux/slab.h>
 #include <net/sock.h>
 #include <linux/uaccess.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:
 		lapb_dbg(1, "(%p) S0 RX SABM(%d)\n", lapb->dev, frame->pf);
 		if (lapb->mode & LAPB_EXTENDED) {
 			lapb_dbg(1, "(%p) S0 TX DM(%d)\n",
 				 lapb->dev, frame->pf);
 			lapb_send_control(lapb, LAPB_DM, frame->pf,
 					  LAPB_RESPONSE);
 		} else {
 			lapb_dbg(1, "(%p) S0 TX UA(%d)\n",
 				 lapb->dev, frame->pf);
 			lapb_dbg(0, "(%p) S0 -> S3\n", lapb->dev);
 			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:
 		lapb_dbg(1, "(%p) S0 RX SABME(%d)\n", lapb->dev, frame->pf);
 		if (lapb->mode & LAPB_EXTENDED) {
 			lapb_dbg(1, "(%p) S0 TX UA(%d)\n",
 				 lapb->dev, frame->pf);
 			lapb_dbg(0, "(%p) S0 -> S3\n", lapb->dev);
 			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 {
 			lapb_dbg(1, "(%p) S0 TX DM(%d)\n",
 				 lapb->dev, frame->pf);
 			lapb_send_control(lapb, LAPB_DM, frame->pf,
 					  LAPB_RESPONSE);
 		}
 		break;

 	case LAPB_DISC:
 		lapb_dbg(1, "(%p) S0 RX DISC(%d)\n", lapb->dev, frame->pf);
 		lapb_dbg(1, "(%p) S0 TX UA(%d)\n", lapb->dev, frame->pf);
 		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:
 		lapb_dbg(1, "(%p) S1 RX SABM(%d)\n", lapb->dev, frame->pf);
 		if (lapb->mode & LAPB_EXTENDED) {
 			lapb_dbg(1, "(%p) S1 TX DM(%d)\n",
 				 lapb->dev, frame->pf);
 			lapb_send_control(lapb, LAPB_DM, frame->pf,
 					  LAPB_RESPONSE);
 		} else {
 			lapb_dbg(1, "(%p) S1 TX UA(%d)\n",
 				 lapb->dev, frame->pf);
 			lapb_send_control(lapb, LAPB_UA, frame->pf,
 					  LAPB_RESPONSE);
 		}
 		break;

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

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

 	case LAPB_UA:
 		lapb_dbg(1, "(%p) S1 RX UA(%d)\n", lapb->dev, frame->pf);
 		if (frame->pf) {
 			lapb_dbg(0, "(%p) S1 -> S3\n", lapb->dev);
 			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:
 		lapb_dbg(1, "(%p) S1 RX DM(%d)\n", lapb->dev, frame->pf);
 		if (frame->pf) {
 			lapb_dbg(0, "(%p) S1 -> S0\n", lapb->dev);
 			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:
 		lapb_dbg(1, "(%p) S2 RX {SABM,SABME}(%d)\n",
 			 lapb->dev, frame->pf);
 		lapb_dbg(1, "(%p) S2 TX DM(%d)\n", lapb->dev, frame->pf);
 		lapb_send_control(lapb, LAPB_DM, frame->pf, LAPB_RESPONSE);
 		break;

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

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

 	case LAPB_DM:
 		lapb_dbg(1, "(%p) S2 RX DM(%d)\n", lapb->dev, frame->pf);
 		if (frame->pf) {
 			lapb_dbg(0, "(%p) S2 -> S0\n", lapb->dev);
 			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:
 		lapb_dbg(1, "(%p) S2 RX {I,REJ,RNR,RR}(%d)\n",
 		       lapb->dev, frame->pf);
 		lapb_dbg(1, "(%p) S2 RX DM(%d)\n", lapb->dev, frame->pf);
 		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:
 		lapb_dbg(1, "(%p) S3 RX SABM(%d)\n", lapb->dev, frame->pf);
 		if (lapb->mode & LAPB_EXTENDED) {
 			lapb_dbg(1, "(%p) S3 TX DM(%d)\n",
 				 lapb->dev, frame->pf);
 			lapb_send_control(lapb, LAPB_DM, frame->pf,
 					  LAPB_RESPONSE);
 		} else {
 			lapb_dbg(1, "(%p) S3 TX UA(%d)\n",
 				 lapb->dev, frame->pf);
 			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:
 		lapb_dbg(1, "(%p) S3 RX SABME(%d)\n", lapb->dev, frame->pf);
 		if (lapb->mode & LAPB_EXTENDED) {
 			lapb_dbg(1, "(%p) S3 TX UA(%d)\n",
 				 lapb->dev, frame->pf);
 			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 {
 			lapb_dbg(1, "(%p) S3 TX DM(%d)\n",
 				 lapb->dev, frame->pf);
 			lapb_send_control(lapb, LAPB_DM, frame->pf,
 					  LAPB_RESPONSE);
 		}
 		break;

 	case LAPB_DISC:
 		lapb_dbg(1, "(%p) S3 RX DISC(%d)\n", lapb->dev, frame->pf);
 		lapb_dbg(0, "(%p) S3 -> S0\n", lapb->dev);
 		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:
 		lapb_dbg(1, "(%p) S3 RX DM(%d)\n", lapb->dev, frame->pf);
 		lapb_dbg(0, "(%p) S3 -> S0\n", lapb->dev);
 		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:
 		lapb_dbg(1, "(%p) S3 RX RNR(%d) R%d\n",
 			 lapb->dev, frame->pf, frame->nr);
 		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);
 			lapb_dbg(0, "(%p) S3 -> S4\n", lapb->dev);
 			lapb_start_t1timer(lapb);
 			lapb_stop_t2timer(lapb);
 			lapb->state   = LAPB_STATE_4;
 			lapb->n2count = 0;
 		}
 		break;

 	case LAPB_RR:
 		lapb_dbg(1, "(%p) S3 RX RR(%d) R%d\n",
 			 lapb->dev, frame->pf, frame->nr);
 		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);
 			lapb_dbg(0, "(%p) S3 -> S4\n", lapb->dev);
 			lapb_start_t1timer(lapb);
 			lapb_stop_t2timer(lapb);
 			lapb->state   = LAPB_STATE_4;
 			lapb->n2count = 0;
 		}
 		break;

 	case LAPB_REJ:
 		lapb_dbg(1, "(%p) S3 RX REJ(%d) R%d\n",
 			 lapb->dev, frame->pf, frame->nr);
 		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);
 			lapb_dbg(0, "(%p) S3 -> S4\n", lapb->dev);
 			lapb_start_t1timer(lapb);
 			lapb_stop_t2timer(lapb);
 			lapb->state   = LAPB_STATE_4;
 			lapb->n2count = 0;
 		}
 		break;

 	case LAPB_I:
 		lapb_dbg(1, "(%p) S3 RX I(%d) S%d R%d\n",
 			 lapb->dev, frame->pf, frame->ns, frame->nr);
 		if (!lapb_validate_nr(lapb, frame->nr)) {
 			lapb->frmr_data = *frame;
 			lapb->frmr_type = LAPB_FRMR_Z;
 			lapb_transmit_frmr(lapb);
 			lapb_dbg(0, "(%p) S3 -> S4\n", lapb->dev);
 			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) {
 				pr_debug("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 {
 				lapb_dbg(1, "(%p) S3 TX REJ(%d) R%d\n",
 					 lapb->dev, frame->pf, lapb->vr);
 				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:
 		lapb_dbg(1, "(%p) S3 RX FRMR(%d) %5ph\n",
 			 lapb->dev, frame->pf,
 			 skb->data);
 		lapb_establish_data_link(lapb);
 		lapb_dbg(0, "(%p) S3 -> S1\n", lapb->dev);
 		lapb_requeue_frames(lapb);
 		lapb->state = LAPB_STATE_1;
 		break;

 	case LAPB_ILLEGAL:
 		lapb_dbg(1, "(%p) S3 RX ILLEGAL(%d)\n", lapb->dev, frame->pf);
 		lapb->frmr_data = *frame;
 		lapb->frmr_type = LAPB_FRMR_W;
 		lapb_transmit_frmr(lapb);
 		lapb_dbg(0, "(%p) S3 -> S4\n", lapb->dev);
 		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:
 		lapb_dbg(1, "(%p) S4 RX SABM(%d)\n", lapb->dev, frame->pf);
 		if (lapb->mode & LAPB_EXTENDED) {
 			lapb_dbg(1, "(%p) S4 TX DM(%d)\n",
 				 lapb->dev, frame->pf);
 			lapb_send_control(lapb, LAPB_DM, frame->pf,
 					  LAPB_RESPONSE);
 		} else {
 			lapb_dbg(1, "(%p) S4 TX UA(%d)\n",
 				 lapb->dev, frame->pf);
 			lapb_dbg(0, "(%p) S4 -> S3\n", lapb->dev);
 			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:
 		lapb_dbg(1, "(%p) S4 RX SABME(%d)\n", lapb->dev, frame->pf);
 		if (lapb->mode & LAPB_EXTENDED) {
 			lapb_dbg(1, "(%p) S4 TX UA(%d)\n",
 				 lapb->dev, frame->pf);
 			lapb_dbg(0, "(%p) S4 -> S3\n", lapb->dev);
 			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 {
 			lapb_dbg(1, "(%p) S4 TX DM(%d)\n",
 				 lapb->dev, frame->pf);
 			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);
 }
	// SPDX-License-Identifier: GPL-2.0-or-later
	/*
	* LAPB release 002
	*
	* This code REQUIRES 2.1.15 or higher/ NET3.038
	*
	* History
	* LAPB 001 Jonathan Naulor Started Coding
	* LAPB 002 Jonathan Naylor New timer architecture.
	* 2000-10-29 Henner Eisen lapb_data_indication() return status.
	*/

	#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

	#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 <linux/slab.h>
	#include <net/sock.h>
	#include <linux/uaccess.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:
	lapb_dbg(1, "(%p) S0 RX SABM(%d)\n", lapb->dev, frame->pf);
	if (lapb->mode & LAPB_EXTENDED) {
	lapb_dbg(1, "(%p) S0 TX DM(%d)\n",
	lapb->dev, frame->pf);
	lapb_send_control(lapb, LAPB_DM, frame->pf,
	LAPB_RESPONSE);
	} else {
	lapb_dbg(1, "(%p) S0 TX UA(%d)\n",
	lapb->dev, frame->pf);
	lapb_dbg(0, "(%p) S0 -> S3\n", lapb->dev);
	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:
	lapb_dbg(1, "(%p) S0 RX SABME(%d)\n", lapb->dev, frame->pf);
	if (lapb->mode & LAPB_EXTENDED) {
	lapb_dbg(1, "(%p) S0 TX UA(%d)\n",
	lapb->dev, frame->pf);
	lapb_dbg(0, "(%p) S0 -> S3\n", lapb->dev);
	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 {
	lapb_dbg(1, "(%p) S0 TX DM(%d)\n",
	lapb->dev, frame->pf);
	lapb_send_control(lapb, LAPB_DM, frame->pf,
	LAPB_RESPONSE);
	}
	break;

	case LAPB_DISC:
	lapb_dbg(1, "(%p) S0 RX DISC(%d)\n", lapb->dev, frame->pf);
	lapb_dbg(1, "(%p) S0 TX UA(%d)\n", lapb->dev, frame->pf);
	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:
	lapb_dbg(1, "(%p) S1 RX SABM(%d)\n", lapb->dev, frame->pf);
	if (lapb->mode & LAPB_EXTENDED) {
	lapb_dbg(1, "(%p) S1 TX DM(%d)\n",
	lapb->dev, frame->pf);
	lapb_send_control(lapb, LAPB_DM, frame->pf,
	LAPB_RESPONSE);
	} else {
	lapb_dbg(1, "(%p) S1 TX UA(%d)\n",
	lapb->dev, frame->pf);
	lapb_send_control(lapb, LAPB_UA, frame->pf,
	LAPB_RESPONSE);
	}
	break;

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

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

	case LAPB_UA:
	lapb_dbg(1, "(%p) S1 RX UA(%d)\n", lapb->dev, frame->pf);
	if (frame->pf) {
	lapb_dbg(0, "(%p) S1 -> S3\n", lapb->dev);
	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:
	lapb_dbg(1, "(%p) S1 RX DM(%d)\n", lapb->dev, frame->pf);
	if (frame->pf) {
	lapb_dbg(0, "(%p) S1 -> S0\n", lapb->dev);
	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:
	lapb_dbg(1, "(%p) S2 RX {SABM,SABME}(%d)\n",
	lapb->dev, frame->pf);
	lapb_dbg(1, "(%p) S2 TX DM(%d)\n", lapb->dev, frame->pf);
	lapb_send_control(lapb, LAPB_DM, frame->pf, LAPB_RESPONSE);
	break;

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

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

	case LAPB_DM:
	lapb_dbg(1, "(%p) S2 RX DM(%d)\n", lapb->dev, frame->pf);
	if (frame->pf) {
	lapb_dbg(0, "(%p) S2 -> S0\n", lapb->dev);
	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:
	lapb_dbg(1, "(%p) S2 RX {I,REJ,RNR,RR}(%d)\n",
	lapb->dev, frame->pf);
	lapb_dbg(1, "(%p) S2 RX DM(%d)\n", lapb->dev, frame->pf);
	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:
	lapb_dbg(1, "(%p) S3 RX SABM(%d)\n", lapb->dev, frame->pf);
	if (lapb->mode & LAPB_EXTENDED) {
	lapb_dbg(1, "(%p) S3 TX DM(%d)\n",
	lapb->dev, frame->pf);
	lapb_send_control(lapb, LAPB_DM, frame->pf,
	LAPB_RESPONSE);
	} else {
	lapb_dbg(1, "(%p) S3 TX UA(%d)\n",
	lapb->dev, frame->pf);
	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:
	lapb_dbg(1, "(%p) S3 RX SABME(%d)\n", lapb->dev, frame->pf);
	if (lapb->mode & LAPB_EXTENDED) {
	lapb_dbg(1, "(%p) S3 TX UA(%d)\n",
	lapb->dev, frame->pf);
	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 {
	lapb_dbg(1, "(%p) S3 TX DM(%d)\n",
	lapb->dev, frame->pf);
	lapb_send_control(lapb, LAPB_DM, frame->pf,
	LAPB_RESPONSE);
	}
	break;

	case LAPB_DISC:
	lapb_dbg(1, "(%p) S3 RX DISC(%d)\n", lapb->dev, frame->pf);
	lapb_dbg(0, "(%p) S3 -> S0\n", lapb->dev);
	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:
	lapb_dbg(1, "(%p) S3 RX DM(%d)\n", lapb->dev, frame->pf);
	lapb_dbg(0, "(%p) S3 -> S0\n", lapb->dev);
	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:
	lapb_dbg(1, "(%p) S3 RX RNR(%d) R%d\n",
	lapb->dev, frame->pf, frame->nr);
	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);
	lapb_dbg(0, "(%p) S3 -> S4\n", lapb->dev);
	lapb_start_t1timer(lapb);
	lapb_stop_t2timer(lapb);
	lapb->state = LAPB_STATE_4;
	lapb->n2count = 0;
	}
	break;

	case LAPB_RR:
	lapb_dbg(1, "(%p) S3 RX RR(%d) R%d\n",
	lapb->dev, frame->pf, frame->nr);
	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);
	lapb_dbg(0, "(%p) S3 -> S4\n", lapb->dev);
	lapb_start_t1timer(lapb);
	lapb_stop_t2timer(lapb);
	lapb->state = LAPB_STATE_4;
	lapb->n2count = 0;
	}
	break;

	case LAPB_REJ:
	lapb_dbg(1, "(%p) S3 RX REJ(%d) R%d\n",
	lapb->dev, frame->pf, frame->nr);
	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);
	lapb_dbg(0, "(%p) S3 -> S4\n", lapb->dev);
	lapb_start_t1timer(lapb);
	lapb_stop_t2timer(lapb);
	lapb->state = LAPB_STATE_4;
	lapb->n2count = 0;
	}
	break;

	case LAPB_I:
	lapb_dbg(1, "(%p) S3 RX I(%d) S%d R%d\n",
	lapb->dev, frame->pf, frame->ns, frame->nr);
	if (!lapb_validate_nr(lapb, frame->nr)) {
	lapb->frmr_data = *frame;
	lapb->frmr_type = LAPB_FRMR_Z;
	lapb_transmit_frmr(lapb);
	lapb_dbg(0, "(%p) S3 -> S4\n", lapb->dev);
	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) {
	pr_debug("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 {
	lapb_dbg(1, "(%p) S3 TX REJ(%d) R%d\n",
	lapb->dev, frame->pf, lapb->vr);
	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:
	lapb_dbg(1, "(%p) S3 RX FRMR(%d) %5ph\n",
	lapb->dev, frame->pf,
	skb->data);
	lapb_establish_data_link(lapb);
	lapb_dbg(0, "(%p) S3 -> S1\n", lapb->dev);
	lapb_requeue_frames(lapb);
	lapb->state = LAPB_STATE_1;
	break;

	case LAPB_ILLEGAL:
	lapb_dbg(1, "(%p) S3 RX ILLEGAL(%d)\n", lapb->dev, frame->pf);
	lapb->frmr_data = *frame;
	lapb->frmr_type = LAPB_FRMR_W;
	lapb_transmit_frmr(lapb);
	lapb_dbg(0, "(%p) S3 -> S4\n", lapb->dev);
	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:
	lapb_dbg(1, "(%p) S4 RX SABM(%d)\n", lapb->dev, frame->pf);
	if (lapb->mode & LAPB_EXTENDED) {
	lapb_dbg(1, "(%p) S4 TX DM(%d)\n",
	lapb->dev, frame->pf);
	lapb_send_control(lapb, LAPB_DM, frame->pf,
	LAPB_RESPONSE);
	} else {
	lapb_dbg(1, "(%p) S4 TX UA(%d)\n",
	lapb->dev, frame->pf);
	lapb_dbg(0, "(%p) S4 -> S3\n", lapb->dev);
	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:
	lapb_dbg(1, "(%p) S4 RX SABME(%d)\n", lapb->dev, frame->pf);
	if (lapb->mode & LAPB_EXTENDED) {
	lapb_dbg(1, "(%p) S4 TX UA(%d)\n",
	lapb->dev, frame->pf);
	lapb_dbg(0, "(%p) S4 -> S3\n", lapb->dev);
	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 {
	lapb_dbg(1, "(%p) S4 TX DM(%d)\n",
	lapb->dev, frame->pf);
	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);
	}