net/ax25/ax25_subr.c - maze/linux - Git at Google

 /*
  * This program is free software; you can redistribute it and/or modify
  * it under the terms of the GNU General Public License as published by
  * the Free Software Foundation; either version 2 of the License, or
  * (at your option) any later version.
  *
  * Copyright (C) Alan Cox GW4PTS (alan@lxorguk.ukuu.org.uk)
  * Copyright (C) Jonathan Naylor G4KLX (g4klx@g4klx.demon.co.uk)
  * Copyright (C) Joerg Reuter DL1BKE (jreuter@yaina.de)
  * Copyright (C) Frederic Rible F1OAT (frible@teaser.fr)
  */
 #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/slab.h>
 #include <net/ax25.h>
 #include <linux/inet.h>
 #include <linux/netdevice.h>
 #include <linux/skbuff.h>
 #include <net/sock.h>
 #include <net/tcp_states.h>
 #include <asm/uaccess.h>
 #include <linux/fcntl.h>
 #include <linux/mm.h>
 #include <linux/interrupt.h>

 /*
  *	This routine purges all the queues of frames.
  */
 void ax25_clear_queues(ax25_cb *ax25)
 {
 	skb_queue_purge(&ax25->write_queue);
 	skb_queue_purge(&ax25->ack_queue);
 	skb_queue_purge(&ax25->reseq_queue);
 	skb_queue_purge(&ax25->frag_queue);
 }

 /*
  * This routine purges the input queue of those frames that have been
  * acknowledged. This replaces the boxes labelled "V(a) <- N(r)" on the
  * SDL diagram.
  */
 void ax25_frames_acked(ax25_cb *ax25, unsigned short nr)
 {
 	struct sk_buff *skb;

 	/*
 	 * Remove all the ack-ed frames from the ack queue.
 	 */
 	if (ax25->va != nr) {
 		while (skb_peek(&ax25->ack_queue) != NULL && ax25->va != nr) {
 			skb = skb_dequeue(&ax25->ack_queue);
 			kfree_skb(skb);
 			ax25->va = (ax25->va + 1) % ax25->modulus;
 		}
 	}
 }

 void ax25_requeue_frames(ax25_cb *ax25)
 {
 	struct sk_buff *skb;

 	/*
 	 * Requeue all the un-ack-ed frames on the output queue to be picked
 	 * up by ax25_kick called from the timer. This arrangement handles the
 	 * possibility of an empty output queue.
 	 */
 	while ((skb = skb_dequeue_tail(&ax25->ack_queue)) != NULL)
 		skb_queue_head(&ax25->write_queue, skb);
 }

 /*
  *	Validate that the value of nr is between va and vs. Return true or
  *	false for testing.
  */
 int ax25_validate_nr(ax25_cb *ax25, unsigned short nr)
 {
 	unsigned short vc = ax25->va;

 	while (vc != ax25->vs) {
 		if (nr == vc) return 1;
 		vc = (vc + 1) % ax25->modulus;
 	}

 	if (nr == ax25->vs) return 1;

 	return 0;
 }

 /*
  *	This routine is the centralised routine for parsing the control
  *	information for the different frame formats.
  */
 int ax25_decode(ax25_cb *ax25, struct sk_buff *skb, int *ns, int *nr, int *pf)
 {
 	unsigned char *frame;
 	int frametype = AX25_ILLEGAL;

 	frame = skb->data;
 	*ns = *nr = *pf = 0;

 	if (ax25->modulus == AX25_MODULUS) {
 		if ((frame[0] & AX25_S) == 0) {
 			frametype = AX25_I;			/* I frame - carries NR/NS/PF */
 			*ns = (frame[0] >> 1) & 0x07;
 			*nr = (frame[0] >> 5) & 0x07;
 			*pf = frame[0] & AX25_PF;
 		} else if ((frame[0] & AX25_U) == 1) { 	/* S frame - take out PF/NR */
 			frametype = frame[0] & 0x0F;
 			*nr = (frame[0] >> 5) & 0x07;
 			*pf = frame[0] & AX25_PF;
 		} else if ((frame[0] & AX25_U) == 3) { 	/* U frame - take out PF */
 			frametype = frame[0] & ~AX25_PF;
 			*pf = frame[0] & AX25_PF;
 		}
 		skb_pull(skb, 1);
 	} else {
 		if ((frame[0] & AX25_S) == 0) {
 			frametype = AX25_I;			/* I frame - carries NR/NS/PF */
 			*ns = (frame[0] >> 1) & 0x7F;
 			*nr = (frame[1] >> 1) & 0x7F;
 			*pf = frame[1] & AX25_EPF;
 			skb_pull(skb, 2);
 		} else if ((frame[0] & AX25_U) == 1) { 	/* S frame - take out PF/NR */
 			frametype = frame[0] & 0x0F;
 			*nr = (frame[1] >> 1) & 0x7F;
 			*pf = frame[1] & AX25_EPF;
 			skb_pull(skb, 2);
 		} else if ((frame[0] & AX25_U) == 3) { 	/* U frame - take out PF */
 			frametype = frame[0] & ~AX25_PF;
 			*pf = frame[0] & AX25_PF;
 			skb_pull(skb, 1);
 		}
 	}

 	return frametype;
 }

 /*
  *	This routine is called when the HDLC layer internally  generates a
  *	command or  response  for  the remote machine ( eg. RR, UA etc. ).
  *	Only supervisory or unnumbered frames are processed.
  */
 void ax25_send_control(ax25_cb *ax25, int frametype, int poll_bit, int type)
 {
 	struct sk_buff *skb;
 	unsigned char  *dptr;

 	if ((skb = alloc_skb(ax25->ax25_dev->dev->hard_header_len + 2, GFP_ATOMIC)) == NULL)
 		return;

 	skb_reserve(skb, ax25->ax25_dev->dev->hard_header_len);

 	skb_reset_network_header(skb);

 	/* Assume a response - address structure for DTE */
 	if (ax25->modulus == AX25_MODULUS) {
 		dptr = skb_put(skb, 1);
 		*dptr = frametype;
 		*dptr |= (poll_bit) ? AX25_PF : 0;
 		if ((frametype & AX25_U) == AX25_S)		/* S frames carry NR */
 			*dptr |= (ax25->vr << 5);
 	} else {
 		if ((frametype & AX25_U) == AX25_U) {
 			dptr = skb_put(skb, 1);
 			*dptr = frametype;
 			*dptr |= (poll_bit) ? AX25_PF : 0;
 		} else {
 			dptr = skb_put(skb, 2);
 			dptr[0] = frametype;
 			dptr[1] = (ax25->vr << 1);
 			dptr[1] |= (poll_bit) ? AX25_EPF : 0;
 		}
 	}

 	ax25_transmit_buffer(ax25, skb, type);
 }

 /*
  *	Send a 'DM' to an unknown connection attempt, or an invalid caller.
  *
  *	Note: src here is the sender, thus it's the target of the DM
  */
 void ax25_return_dm(struct net_device *dev, ax25_address *src, ax25_address *dest, ax25_digi *digi)
 {
 	struct sk_buff *skb;
 	char *dptr;
 	ax25_digi retdigi;

 	if (dev == NULL)
 		return;

 	if ((skb = alloc_skb(dev->hard_header_len + 1, GFP_ATOMIC)) == NULL)
 		return;	/* Next SABM will get DM'd */

 	skb_reserve(skb, dev->hard_header_len);
 	skb_reset_network_header(skb);

 	ax25_digi_invert(digi, &retdigi);

 	dptr = skb_put(skb, 1);

 	*dptr = AX25_DM | AX25_PF;

 	/*
 	 *	Do the address ourselves
 	 */
 	dptr  = skb_push(skb, ax25_addr_size(digi));
 	dptr += ax25_addr_build(dptr, dest, src, &retdigi, AX25_RESPONSE, AX25_MODULUS);

 	ax25_queue_xmit(skb, dev);
 }

 /*
  *	Exponential backoff for AX.25
  */
 void ax25_calculate_t1(ax25_cb *ax25)
 {
 	int n, t = 2;

 	switch (ax25->backoff) {
 	case 0:
 		break;

 	case 1:
 		t += 2 * ax25->n2count;
 		break;

 	case 2:
 		for (n = 0; n < ax25->n2count; n++)
 			t *= 2;
 		if (t > 8) t = 8;
 		break;
 	}

 	ax25->t1 = t * ax25->rtt;
 }

 /*
  *	Calculate the Round Trip Time
  */
 void ax25_calculate_rtt(ax25_cb *ax25)
 {
 	if (ax25->backoff == 0)
 		return;

 	if (ax25_t1timer_running(ax25) && ax25->n2count == 0)
 		ax25->rtt = (9 * ax25->rtt + ax25->t1 - ax25_display_timer(&ax25->t1timer)) / 10;

 	if (ax25->rtt < AX25_T1CLAMPLO)
 		ax25->rtt = AX25_T1CLAMPLO;

 	if (ax25->rtt > AX25_T1CLAMPHI)
 		ax25->rtt = AX25_T1CLAMPHI;
 }

 void ax25_disconnect(ax25_cb *ax25, int reason)
 {
 	ax25_clear_queues(ax25);

 	ax25_stop_t1timer(ax25);
 	ax25_stop_t2timer(ax25);
 	ax25_stop_t3timer(ax25);
 	ax25_stop_idletimer(ax25);

 	ax25->state = AX25_STATE_0;

 	ax25_link_failed(ax25, reason);

 	if (ax25->sk != NULL) {
 		local_bh_disable();
 		bh_lock_sock(ax25->sk);
 		ax25->sk->sk_state     = TCP_CLOSE;
 		ax25->sk->sk_err       = reason;
 		ax25->sk->sk_shutdown |= SEND_SHUTDOWN;
 		if (!sock_flag(ax25->sk, SOCK_DEAD)) {
 			ax25->sk->sk_state_change(ax25->sk);
 			sock_set_flag(ax25->sk, SOCK_DEAD);
 		}
 		bh_unlock_sock(ax25->sk);
 		local_bh_enable();
 	}
 }
	/*
	* This program is free software; you can redistribute it and/or modify
	* it under the terms of the GNU General Public License as published by
	* the Free Software Foundation; either version 2 of the License, or
	* (at your option) any later version.
	*
	* Copyright (C) Alan Cox GW4PTS (alan@lxorguk.ukuu.org.uk)
	* Copyright (C) Jonathan Naylor G4KLX (g4klx@g4klx.demon.co.uk)
	* Copyright (C) Joerg Reuter DL1BKE (jreuter@yaina.de)
	* Copyright (C) Frederic Rible F1OAT (frible@teaser.fr)
	*/
	#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/slab.h>
	#include <net/ax25.h>
	#include <linux/inet.h>
	#include <linux/netdevice.h>
	#include <linux/skbuff.h>
	#include <net/sock.h>
	#include <net/tcp_states.h>
	#include <asm/uaccess.h>
	#include <linux/fcntl.h>
	#include <linux/mm.h>
	#include <linux/interrupt.h>

	/*
	* This routine purges all the queues of frames.
	*/
	void ax25_clear_queues(ax25_cb *ax25)
	{
	skb_queue_purge(&ax25->write_queue);
	skb_queue_purge(&ax25->ack_queue);
	skb_queue_purge(&ax25->reseq_queue);
	skb_queue_purge(&ax25->frag_queue);
	}

	/*
	* This routine purges the input queue of those frames that have been
	* acknowledged. This replaces the boxes labelled "V(a) <- N(r)" on the
	* SDL diagram.
	*/
	void ax25_frames_acked(ax25_cb *ax25, unsigned short nr)
	{
	struct sk_buff *skb;

	/*
	* Remove all the ack-ed frames from the ack queue.
	*/
	if (ax25->va != nr) {
	while (skb_peek(&ax25->ack_queue) != NULL && ax25->va != nr) {
	skb = skb_dequeue(&ax25->ack_queue);
	kfree_skb(skb);
	ax25->va = (ax25->va + 1) % ax25->modulus;
	}
	}
	}

	void ax25_requeue_frames(ax25_cb *ax25)
	{
	struct sk_buff *skb;

	/*
	* Requeue all the un-ack-ed frames on the output queue to be picked
	* up by ax25_kick called from the timer. This arrangement handles the
	* possibility of an empty output queue.
	*/
	while ((skb = skb_dequeue_tail(&ax25->ack_queue)) != NULL)
	skb_queue_head(&ax25->write_queue, skb);
	}

	/*
	* Validate that the value of nr is between va and vs. Return true or
	* false for testing.
	*/
	int ax25_validate_nr(ax25_cb *ax25, unsigned short nr)
	{
	unsigned short vc = ax25->va;

	while (vc != ax25->vs) {
	if (nr == vc) return 1;
	vc = (vc + 1) % ax25->modulus;
	}

	if (nr == ax25->vs) return 1;

	return 0;
	}

	/*
	* This routine is the centralised routine for parsing the control
	* information for the different frame formats.
	*/
	int ax25_decode(ax25_cb ax25, struct sk_buff skb, int ns, int nr, int *pf)
	{
	unsigned char *frame;
	int frametype = AX25_ILLEGAL;

	frame = skb->data;
	ns = nr = *pf = 0;

	if (ax25->modulus == AX25_MODULUS) {
	if ((frame[0] & AX25_S) == 0) {
	frametype = AX25_I; /* I frame - carries NR/NS/PF */
	*ns = (frame[0] >> 1) & 0x07;
	*nr = (frame[0] >> 5) & 0x07;
	*pf = frame[0] & AX25_PF;
	} else if ((frame[0] & AX25_U) == 1) { /* S frame - take out PF/NR */
	frametype = frame[0] & 0x0F;
	*nr = (frame[0] >> 5) & 0x07;
	*pf = frame[0] & AX25_PF;
	} else if ((frame[0] & AX25_U) == 3) { /* U frame - take out PF */
	frametype = frame[0] & ~AX25_PF;
	*pf = frame[0] & AX25_PF;
	}
	skb_pull(skb, 1);
	} else {
	if ((frame[0] & AX25_S) == 0) {
	frametype = AX25_I; /* I frame - carries NR/NS/PF */
	*ns = (frame[0] >> 1) & 0x7F;
	*nr = (frame[1] >> 1) & 0x7F;
	*pf = frame[1] & AX25_EPF;
	skb_pull(skb, 2);
	} else if ((frame[0] & AX25_U) == 1) { /* S frame - take out PF/NR */
	frametype = frame[0] & 0x0F;
	*nr = (frame[1] >> 1) & 0x7F;
	*pf = frame[1] & AX25_EPF;
	skb_pull(skb, 2);
	} else if ((frame[0] & AX25_U) == 3) { /* U frame - take out PF */
	frametype = frame[0] & ~AX25_PF;
	*pf = frame[0] & AX25_PF;
	skb_pull(skb, 1);
	}
	}

	return frametype;
	}

	/*
	* This routine is called when the HDLC layer internally generates a
	* command or response for the remote machine ( eg. RR, UA etc. ).
	* Only supervisory or unnumbered frames are processed.
	*/
	void ax25_send_control(ax25_cb *ax25, int frametype, int poll_bit, int type)
	{
	struct sk_buff *skb;
	unsigned char *dptr;

	if ((skb = alloc_skb(ax25->ax25_dev->dev->hard_header_len + 2, GFP_ATOMIC)) == NULL)
	return;

	skb_reserve(skb, ax25->ax25_dev->dev->hard_header_len);

	skb_reset_network_header(skb);

	/* Assume a response - address structure for DTE */
	if (ax25->modulus == AX25_MODULUS) {
	dptr = skb_put(skb, 1);
	*dptr = frametype;
	*dptr \|= (poll_bit) ? AX25_PF : 0;
	if ((frametype & AX25_U) == AX25_S) /* S frames carry NR */
	*dptr \|= (ax25->vr << 5);
	} else {
	if ((frametype & AX25_U) == AX25_U) {
	dptr = skb_put(skb, 1);
	*dptr = frametype;
	*dptr \|= (poll_bit) ? AX25_PF : 0;
	} else {
	dptr = skb_put(skb, 2);
	dptr[0] = frametype;
	dptr[1] = (ax25->vr << 1);
	dptr[1] \|= (poll_bit) ? AX25_EPF : 0;
	}
	}

	ax25_transmit_buffer(ax25, skb, type);
	}

	/*
	* Send a 'DM' to an unknown connection attempt, or an invalid caller.
	*
	* Note: src here is the sender, thus it's the target of the DM
	*/
	void ax25_return_dm(struct net_device dev, ax25_address src, ax25_address dest, ax25_digi digi)
	{
	struct sk_buff *skb;
	char *dptr;
	ax25_digi retdigi;

	if (dev == NULL)
	return;

	if ((skb = alloc_skb(dev->hard_header_len + 1, GFP_ATOMIC)) == NULL)
	return; /* Next SABM will get DM'd */

	skb_reserve(skb, dev->hard_header_len);
	skb_reset_network_header(skb);

	ax25_digi_invert(digi, &retdigi);

	dptr = skb_put(skb, 1);

	*dptr = AX25_DM \| AX25_PF;

	/*
	* Do the address ourselves
	*/
	dptr = skb_push(skb, ax25_addr_size(digi));
	dptr += ax25_addr_build(dptr, dest, src, &retdigi, AX25_RESPONSE, AX25_MODULUS);

	ax25_queue_xmit(skb, dev);
	}

	/*
	* Exponential backoff for AX.25
	*/
	void ax25_calculate_t1(ax25_cb *ax25)
	{
	int n, t = 2;

	switch (ax25->backoff) {
	case 0:
	break;

	case 1:
	t += 2 * ax25->n2count;
	break;

	case 2:
	for (n = 0; n < ax25->n2count; n++)
	t *= 2;
	if (t > 8) t = 8;
	break;
	}

	ax25->t1 = t * ax25->rtt;
	}

	/*
	* Calculate the Round Trip Time
	*/
	void ax25_calculate_rtt(ax25_cb *ax25)
	{
	if (ax25->backoff == 0)
	return;

	if (ax25_t1timer_running(ax25) && ax25->n2count == 0)
	ax25->rtt = (9 * ax25->rtt + ax25->t1 - ax25_display_timer(&ax25->t1timer)) / 10;

	if (ax25->rtt < AX25_T1CLAMPLO)
	ax25->rtt = AX25_T1CLAMPLO;

	if (ax25->rtt > AX25_T1CLAMPHI)
	ax25->rtt = AX25_T1CLAMPHI;
	}

	void ax25_disconnect(ax25_cb *ax25, int reason)
	{
	ax25_clear_queues(ax25);

	ax25_stop_t1timer(ax25);
	ax25_stop_t2timer(ax25);
	ax25_stop_t3timer(ax25);
	ax25_stop_idletimer(ax25);

	ax25->state = AX25_STATE_0;

	ax25_link_failed(ax25, reason);

	if (ax25->sk != NULL) {
	local_bh_disable();
	bh_lock_sock(ax25->sk);
	ax25->sk->sk_state = TCP_CLOSE;
	ax25->sk->sk_err = reason;
	ax25->sk->sk_shutdown \|= SEND_SHUTDOWN;
	if (!sock_flag(ax25->sk, SOCK_DEAD)) {
	ax25->sk->sk_state_change(ax25->sk);
	sock_set_flag(ax25->sk, SOCK_DEAD);
	}
	bh_unlock_sock(ax25->sk);
	local_bh_enable();
	}
	}