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net/ax25/ax25_ds_in.c 6.87 KB
2874c5fd2   Thomas Gleixner   treewide: Replace...
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  // SPDX-License-Identifier: GPL-2.0-or-later
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  /*
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   *
   * Copyright (C) Jonathan Naylor G4KLX (g4klx@g4klx.demon.co.uk)
   * Copyright (C) Joerg Reuter DL1BKE (jreuter@yaina.de)
   */
  #include <linux/errno.h>
  #include <linux/types.h>
  #include <linux/socket.h>
  #include <linux/in.h>
  #include <linux/kernel.h>
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  #include <linux/timer.h>
  #include <linux/string.h>
  #include <linux/sockios.h>
  #include <linux/net.h>
  #include <net/ax25.h>
  #include <linux/inet.h>
  #include <linux/netdevice.h>
  #include <linux/skbuff.h>
  #include <net/sock.h>
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  #include <net/tcp_states.h>
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  #include <linux/uaccess.h>
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  #include <linux/fcntl.h>
  #include <linux/mm.h>
  #include <linux/interrupt.h>
  
  /*
   *	State machine for state 1, Awaiting Connection State.
   *	The handling of the timer(s) is in file ax25_ds_timer.c.
   *	Handling of state 0 and connection release is in ax25.c.
   */
  static int ax25_ds_state1_machine(ax25_cb *ax25, struct sk_buff *skb, int frametype, int pf, int type)
  {
  	switch (frametype) {
  	case AX25_SABM:
  		ax25->modulus = AX25_MODULUS;
  		ax25->window  = ax25->ax25_dev->values[AX25_VALUES_WINDOW];
  		ax25_send_control(ax25, AX25_UA, pf, AX25_RESPONSE);
  		break;
  
  	case AX25_SABME:
  		ax25->modulus = AX25_EMODULUS;
  		ax25->window  =  ax25->ax25_dev->values[AX25_VALUES_EWINDOW];
  		ax25_send_control(ax25, AX25_UA, pf, AX25_RESPONSE);
  		break;
  
  	case AX25_DISC:
  		ax25_send_control(ax25, AX25_DM, pf, AX25_RESPONSE);
  		break;
  
  	case AX25_UA:
  		ax25_calculate_rtt(ax25);
  		ax25_stop_t1timer(ax25);
  		ax25_start_t3timer(ax25);
  		ax25_start_idletimer(ax25);
  		ax25->vs      = 0;
  		ax25->va      = 0;
  		ax25->vr      = 0;
  		ax25->state   = AX25_STATE_3;
  		ax25->n2count = 0;
  		if (ax25->sk != NULL) {
  			bh_lock_sock(ax25->sk);
  			ax25->sk->sk_state = TCP_ESTABLISHED;
  			/*
  			 * For WAIT_SABM connections we will produce an accept
  			 * ready socket here
  			 */
  			if (!sock_flag(ax25->sk, SOCK_DEAD))
  				ax25->sk->sk_state_change(ax25->sk);
  			bh_unlock_sock(ax25->sk);
  		}
  		ax25_dama_on(ax25);
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  		/* according to DK4EG's spec we are required to
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  		 * send a RR RESPONSE FINAL NR=0.
  		 */
  
  		ax25_std_enquiry_response(ax25);
  		break;
  
  	case AX25_DM:
  		if (pf)
  			ax25_disconnect(ax25, ECONNREFUSED);
  		break;
  
  	default:
  		if (pf)
  			ax25_send_control(ax25, AX25_SABM, AX25_POLLON, AX25_COMMAND);
  		break;
  	}
  
  	return 0;
  }
  
  /*
   *	State machine for state 2, Awaiting Release State.
   *	The handling of the timer(s) is in file ax25_ds_timer.c
   *	Handling of state 0 and connection release is in ax25.c.
   */
  static int ax25_ds_state2_machine(ax25_cb *ax25, struct sk_buff *skb, int frametype, int pf, int type)
  {
  	switch (frametype) {
  	case AX25_SABM:
  	case AX25_SABME:
  		ax25_send_control(ax25, AX25_DISC, AX25_POLLON, AX25_COMMAND);
  		ax25_dama_off(ax25);
  		break;
  
  	case AX25_DISC:
  		ax25_send_control(ax25, AX25_UA, pf, AX25_RESPONSE);
  		ax25_dama_off(ax25);
  		ax25_disconnect(ax25, 0);
  		break;
  
  	case AX25_DM:
  	case AX25_UA:
  		if (pf) {
  			ax25_dama_off(ax25);
  			ax25_disconnect(ax25, 0);
  		}
  		break;
  
  	case AX25_I:
  	case AX25_REJ:
  	case AX25_RNR:
  	case AX25_RR:
  		if (pf) {
  			ax25_send_control(ax25, AX25_DISC, AX25_POLLON, AX25_COMMAND);
  			ax25_dama_off(ax25);
  		}
  		break;
  
  	default:
  		break;
  	}
  
  	return 0;
  }
  
  /*
   *	State machine for state 3, Connected State.
   *	The handling of the timer(s) is in file ax25_timer.c
   *	Handling of state 0 and connection release is in ax25.c.
   */
  static int ax25_ds_state3_machine(ax25_cb *ax25, struct sk_buff *skb, int frametype, int ns, int nr, int pf, int type)
  {
  	int queued = 0;
  
  	switch (frametype) {
  	case AX25_SABM:
  	case AX25_SABME:
  		if (frametype == AX25_SABM) {
  			ax25->modulus   = AX25_MODULUS;
  			ax25->window    = ax25->ax25_dev->values[AX25_VALUES_WINDOW];
  		} else {
  			ax25->modulus   = AX25_EMODULUS;
  			ax25->window    = ax25->ax25_dev->values[AX25_VALUES_EWINDOW];
  		}
  		ax25_send_control(ax25, AX25_UA, pf, AX25_RESPONSE);
  		ax25_stop_t1timer(ax25);
  		ax25_start_t3timer(ax25);
  		ax25_start_idletimer(ax25);
  		ax25->condition = 0x00;
  		ax25->vs        = 0;
  		ax25->va        = 0;
  		ax25->vr        = 0;
  		ax25_requeue_frames(ax25);
  		ax25_dama_on(ax25);
  		break;
  
  	case AX25_DISC:
  		ax25_send_control(ax25, AX25_UA, pf, AX25_RESPONSE);
  		ax25_dama_off(ax25);
  		ax25_disconnect(ax25, 0);
  		break;
  
  	case AX25_DM:
  		ax25_dama_off(ax25);
  		ax25_disconnect(ax25, ECONNRESET);
  		break;
  
  	case AX25_RR:
  	case AX25_RNR:
  		if (frametype == AX25_RR)
  			ax25->condition &= ~AX25_COND_PEER_RX_BUSY;
  		else
  			ax25->condition |= AX25_COND_PEER_RX_BUSY;
  
  		if (ax25_validate_nr(ax25, nr)) {
  			if (ax25_check_iframes_acked(ax25, nr))
  				ax25->n2count=0;
  			if (type == AX25_COMMAND && pf)
  				ax25_ds_enquiry_response(ax25);
  		} else {
  			ax25_ds_nr_error_recovery(ax25);
  			ax25->state = AX25_STATE_1;
  		}
  		break;
  
  	case AX25_REJ:
  		ax25->condition &= ~AX25_COND_PEER_RX_BUSY;
  
  		if (ax25_validate_nr(ax25, nr)) {
  			if (ax25->va != nr)
  				ax25->n2count=0;
  
  			ax25_frames_acked(ax25, nr);
  			ax25_calculate_rtt(ax25);
  			ax25_stop_t1timer(ax25);
  			ax25_start_t3timer(ax25);
  			ax25_requeue_frames(ax25);
  
  			if (type == AX25_COMMAND && pf)
  				ax25_ds_enquiry_response(ax25);
  		} else {
  			ax25_ds_nr_error_recovery(ax25);
  			ax25->state = AX25_STATE_1;
  		}
  		break;
  
  	case AX25_I:
  		if (!ax25_validate_nr(ax25, nr)) {
  			ax25_ds_nr_error_recovery(ax25);
  			ax25->state = AX25_STATE_1;
  			break;
  		}
  		if (ax25->condition & AX25_COND_PEER_RX_BUSY) {
  			ax25_frames_acked(ax25, nr);
  			ax25->n2count = 0;
  		} else {
  			if (ax25_check_iframes_acked(ax25, nr))
  				ax25->n2count = 0;
  		}
  		if (ax25->condition & AX25_COND_OWN_RX_BUSY) {
  			if (pf) ax25_ds_enquiry_response(ax25);
  			break;
  		}
  		if (ns == ax25->vr) {
  			ax25->vr = (ax25->vr + 1) % ax25->modulus;
  			queued = ax25_rx_iframe(ax25, skb);
  			if (ax25->condition & AX25_COND_OWN_RX_BUSY)
  				ax25->vr = ns;	/* ax25->vr - 1 */
  			ax25->condition &= ~AX25_COND_REJECT;
  			if (pf) {
  				ax25_ds_enquiry_response(ax25);
  			} else {
  				if (!(ax25->condition & AX25_COND_ACK_PENDING)) {
  					ax25->condition |= AX25_COND_ACK_PENDING;
  					ax25_start_t2timer(ax25);
  				}
  			}
  		} else {
  			if (ax25->condition & AX25_COND_REJECT) {
  				if (pf) ax25_ds_enquiry_response(ax25);
  			} else {
  				ax25->condition |= AX25_COND_REJECT;
  				ax25_ds_enquiry_response(ax25);
  				ax25->condition &= ~AX25_COND_ACK_PENDING;
  			}
  		}
  		break;
  
  	case AX25_FRMR:
  	case AX25_ILLEGAL:
  		ax25_ds_establish_data_link(ax25);
  		ax25->state = AX25_STATE_1;
  		break;
  
  	default:
  		break;
  	}
  
  	return queued;
  }
  
  /*
   *	Higher level upcall for a LAPB frame
   */
  int ax25_ds_frame_in(ax25_cb *ax25, struct sk_buff *skb, int type)
  {
  	int queued = 0, frametype, ns, nr, pf;
  
  	frametype = ax25_decode(ax25, skb, &ns, &nr, &pf);
  
  	switch (ax25->state) {
  	case AX25_STATE_1:
  		queued = ax25_ds_state1_machine(ax25, skb, frametype, pf, type);
  		break;
  	case AX25_STATE_2:
  		queued = ax25_ds_state2_machine(ax25, skb, frametype, pf, type);
  		break;
  	case AX25_STATE_3:
  		queued = ax25_ds_state3_machine(ax25, skb, frametype, ns, nr, pf, type);
  		break;
  	}
  
  	return queued;
  }