[linux-2.6-block.git] / net / ax25 / ax25_subr.c

/*
 * 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 <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 <asm/system.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, *skb_prev = NULL;

	/*
	 * 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(&ax25->ack_queue)) != NULL) {
		if (skb_prev == NULL)
			skb_queue_head(&ax25->write_queue, skb);
		else
			skb_append(skb_prev, skb, &ax25->write_queue);
		skb_prev = 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();
	}
}
Commit	Line	Data
1da177e4 LT	1	/*
	2	* This program is free software; you can redistribute it and/or modify
	3	* it under the terms of the GNU General Public License as published by
	4	* the Free Software Foundation; either version 2 of the License, or
	5	* (at your option) any later version.
	6	*
	7	* Copyright (C) Alan Cox GW4PTS (alan@lxorguk.ukuu.org.uk)
	8	* Copyright (C) Jonathan Naylor G4KLX (g4klx@g4klx.demon.co.uk)
	9	* Copyright (C) Joerg Reuter DL1BKE (jreuter@yaina.de)
	10	* Copyright (C) Frederic Rible F1OAT (frible@teaser.fr)
	11	*/
	12	#include <linux/errno.h>
	13	#include <linux/types.h>
	14	#include <linux/socket.h>
	15	#include <linux/in.h>
	16	#include <linux/kernel.h>
1da177e4 LT	17	#include <linux/timer.h>
	18	#include <linux/string.h>
	19	#include <linux/sockios.h>
	20	#include <linux/net.h>
	21	#include <net/ax25.h>
	22	#include <linux/inet.h>
	23	#include <linux/netdevice.h>
	24	#include <linux/skbuff.h>
	25	#include <net/sock.h>
c752f073	26	#include <net/tcp_states.h>
1da177e4 LT	27	#include <asm/uaccess.h>
	28	#include <asm/system.h>
	29	#include <linux/fcntl.h>
	30	#include <linux/mm.h>
	31	#include <linux/interrupt.h>
	32
	33	/*
	34	* This routine purges all the queues of frames.
	35	*/
	36	void ax25_clear_queues(ax25_cb *ax25)
	37	{
	38	skb_queue_purge(&ax25->write_queue);
	39	skb_queue_purge(&ax25->ack_queue);
	40	skb_queue_purge(&ax25->reseq_queue);
	41	skb_queue_purge(&ax25->frag_queue);
	42	}
	43
	44	/*
	45	* This routine purges the input queue of those frames that have been
	46	* acknowledged. This replaces the boxes labelled "V(a) <- N(r)" on the
	47	* SDL diagram.
	48	*/
	49	void ax25_frames_acked(ax25_cb *ax25, unsigned short nr)
	50	{
	51	struct sk_buff *skb;
	52
	53	/*
	54	* Remove all the ack-ed frames from the ack queue.
	55	*/
	56	if (ax25->va != nr) {
	57	while (skb_peek(&ax25->ack_queue) != NULL && ax25->va != nr) {
528930b9	58	skb = skb_dequeue(&ax25->ack_queue);
1da177e4 LT	59	kfree_skb(skb);
	60	ax25->va = (ax25->va + 1) % ax25->modulus;
	61	}
	62	}
	63	}
	64
	65	void ax25_requeue_frames(ax25_cb *ax25)
	66	{
528930b9	67	struct sk_buff skb, skb_prev = NULL;
1da177e4 LT	68
	69	/*
	70	* Requeue all the un-ack-ed frames on the output queue to be picked
	71	* up by ax25_kick called from the timer. This arrangement handles the
	72	* possibility of an empty output queue.
	73	*/
	74	while ((skb = skb_dequeue(&ax25->ack_queue)) != NULL) {
	75	if (skb_prev == NULL)
	76	skb_queue_head(&ax25->write_queue, skb);
	77	else
8728b834	78	skb_append(skb_prev, skb, &ax25->write_queue);
1da177e4 LT	79	skb_prev = skb;
	80	}
	81	}
	82
	83	/*
	84	* Validate that the value of nr is between va and vs. Return true or
	85	* false for testing.
	86	*/
	87	int ax25_validate_nr(ax25_cb *ax25, unsigned short nr)
	88	{
	89	unsigned short vc = ax25->va;
	90
	91	while (vc != ax25->vs) {
	92	if (nr == vc) return 1;
	93	vc = (vc + 1) % ax25->modulus;
	94	}
	95
	96	if (nr == ax25->vs) return 1;
	97
	98	return 0;
	99	}
	100
	101	/*
	102	* This routine is the centralised routine for parsing the control
	103	* information for the different frame formats.
	104	*/
	105	int ax25_decode(ax25_cb ax25, struct sk_buff skb, int ns, int nr, int *pf)
	106	{
	107	unsigned char *frame;
	108	int frametype = AX25_ILLEGAL;
	109
	110	frame = skb->data;
	111	ns = nr = *pf = 0;
	112
	113	if (ax25->modulus == AX25_MODULUS) {
	114	if ((frame[0] & AX25_S) == 0) {
	115	frametype = AX25_I; /* I frame - carries NR/NS/PF */
	116	*ns = (frame[0] >> 1) & 0x07;
	117	*nr = (frame[0] >> 5) & 0x07;
	118	*pf = frame[0] & AX25_PF;
	119	} else if ((frame[0] & AX25_U) == 1) { /* S frame - take out PF/NR */
	120	frametype = frame[0] & 0x0F;
	121	*nr = (frame[0] >> 5) & 0x07;
	122	*pf = frame[0] & AX25_PF;
	123	} else if ((frame[0] & AX25_U) == 3) { /* U frame - take out PF */
	124	frametype = frame[0] & ~AX25_PF;
	125	*pf = frame[0] & AX25_PF;
	126	}
	127	skb_pull(skb, 1);
	128	} else {
	129	if ((frame[0] & AX25_S) == 0) {
	130	frametype = AX25_I; /* I frame - carries NR/NS/PF */
	131	*ns = (frame[0] >> 1) & 0x7F;
	132	*nr = (frame[1] >> 1) & 0x7F;
	133	*pf = frame[1] & AX25_EPF;
	134	skb_pull(skb, 2);
	135	} else if ((frame[0] & AX25_U) == 1) { /* S frame - take out PF/NR */
	136	frametype = frame[0] & 0x0F;
	137	*nr = (frame[1] >> 1) & 0x7F;
	138	*pf = frame[1] & AX25_EPF;
	139	skb_pull(skb, 2);
	140	} else if ((frame[0] & AX25_U) == 3) { /* U frame - take out PF */
	141	frametype = frame[0] & ~AX25_PF;
	142	*pf = frame[0] & AX25_PF;
143	skb_pull(skb, 1);
144	}
145	}
146
147	return frametype;
148	}
149
150	/*
151	* This routine is called when the HDLC layer internally generates a
152	* command or response for the remote machine ( eg. RR, UA etc. ).
153	* Only supervisory or unnumbered frames are processed.
154	*/
155	void ax25_send_control(ax25_cb *ax25, int frametype, int poll_bit, int type)
156	{
157	struct sk_buff *skb;
158	unsigned char *dptr;
159
160	if ((skb = alloc_skb(ax25->ax25_dev->dev->hard_header_len + 2, GFP_ATOMIC)) == NULL)
161	return;
162
163	skb_reserve(skb, ax25->ax25_dev->dev->hard_header_len);
164
c1d2bbe1	165	skb_reset_network_header(skb);
1da177e4 LT	166
	167	/* Assume a response - address structure for DTE */
	168	if (ax25->modulus == AX25_MODULUS) {
	169	dptr = skb_put(skb, 1);
	170	*dptr = frametype;
	171	*dptr \|= (poll_bit) ? AX25_PF : 0;
	172	if ((frametype & AX25_U) == AX25_S) /* S frames carry NR */
	173	*dptr \|= (ax25->vr << 5);
	174	} else {
	175	if ((frametype & AX25_U) == AX25_U) {
	176	dptr = skb_put(skb, 1);
	177	*dptr = frametype;
	178	*dptr \|= (poll_bit) ? AX25_PF : 0;
	179	} else {
	180	dptr = skb_put(skb, 2);
	181	dptr[0] = frametype;
	182	dptr[1] = (ax25->vr << 1);
	183	dptr[1] \|= (poll_bit) ? AX25_EPF : 0;
	184	}
	185	}
	186
	187	ax25_transmit_buffer(ax25, skb, type);
	188	}
	189
	190	/*
	191	* Send a 'DM' to an unknown connection attempt, or an invalid caller.
	192	*
	193	* Note: src here is the sender, thus it's the target of the DM
	194	*/
	195	void ax25_return_dm(struct net_device dev, ax25_address src, ax25_address dest, ax25_digi digi)
	196	{
	197	struct sk_buff *skb;
	198	char *dptr;
	199	ax25_digi retdigi;
	200
	201	if (dev == NULL)
	202	return;
	203
	204	if ((skb = alloc_skb(dev->hard_header_len + 1, GFP_ATOMIC)) == NULL)
	205	return; /* Next SABM will get DM'd */
	206
	207	skb_reserve(skb, dev->hard_header_len);
c1d2bbe1	208	skb_reset_network_header(skb);
1da177e4 LT	209
	210	ax25_digi_invert(digi, &retdigi);
	211
	212	dptr = skb_put(skb, 1);
	213
	214	*dptr = AX25_DM \| AX25_PF;
	215
	216	/*
	217	* Do the address ourselves
	218	*/
	219	dptr = skb_push(skb, ax25_addr_size(digi));
	220	dptr += ax25_addr_build(dptr, dest, src, &retdigi, AX25_RESPONSE, AX25_MODULUS);
	221
29c4be51	222	ax25_queue_xmit(skb, dev);
1da177e4 LT	223	}
	224
	225	/*
	226	* Exponential backoff for AX.25
	227	*/
	228	void ax25_calculate_t1(ax25_cb *ax25)
	229	{
	230	int n, t = 2;
	231
	232	switch (ax25->backoff) {
	233	case 0:
	234	break;
	235
	236	case 1:
	237	t += 2 * ax25->n2count;
	238	break;
	239
	240	case 2:
	241	for (n = 0; n < ax25->n2count; n++)
	242	t *= 2;
	243	if (t > 8) t = 8;
	244	break;
	245	}
	246
	247	ax25->t1 = t * ax25->rtt;
	248	}
	249
	250	/*
	251	* Calculate the Round Trip Time
	252	*/
	253	void ax25_calculate_rtt(ax25_cb *ax25)
	254	{
	255	if (ax25->backoff == 0)
	256	return;
	257
	258	if (ax25_t1timer_running(ax25) && ax25->n2count == 0)
	259	ax25->rtt = (9 * ax25->rtt + ax25->t1 - ax25_display_timer(&ax25->t1timer)) / 10;
	260
	261	if (ax25->rtt < AX25_T1CLAMPLO)
	262	ax25->rtt = AX25_T1CLAMPLO;
	263
	264	if (ax25->rtt > AX25_T1CLAMPHI)
	265	ax25->rtt = AX25_T1CLAMPHI;
	266	}
	267
	268	void ax25_disconnect(ax25_cb *ax25, int reason)
	269	{
	270	ax25_clear_queues(ax25);
	271
	272	ax25_stop_t1timer(ax25);
	273	ax25_stop_t2timer(ax25);
	274	ax25_stop_t3timer(ax25);
	275	ax25_stop_idletimer(ax25);
	276
	277	ax25->state = AX25_STATE_0;
	278
	279	ax25_link_failed(ax25, reason);
	280
	281	if (ax25->sk != NULL) {
215f7b08	282	local_bh_disable();
1da177e4 LT	283	bh_lock_sock(ax25->sk);
	284	ax25->sk->sk_state = TCP_CLOSE;
	285	ax25->sk->sk_err = reason;
	286	ax25->sk->sk_shutdown \|= SEND_SHUTDOWN;
	287	if (!sock_flag(ax25->sk, SOCK_DEAD)) {
	288	ax25->sk->sk_state_change(ax25->sk);
	289	sock_set_flag(ax25->sk, SOCK_DEAD);
	290	}
	291	bh_unlock_sock(ax25->sk);
215f7b08	292	local_bh_enable();
1da177e4 LT	293	}
1da177e4 LT	294	}