[linux.git] / net / x25 / x25_out.c

/*
 *	X.25 Packet Layer release 002
 *
 *	This is ALPHA test software. This code may break your machine,
 *	randomly fail to work with new releases, misbehave and/or generally
 *	screw up. It might even work.
 *
 *	This code REQUIRES 2.1.15 or higher
 *
 *	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
 *	X.25 001	Jonathan Naylor	Started coding.
 *	X.25 002	Jonathan Naylor	New timer architecture.
 *	2000-09-04	Henner Eisen	Prevented x25_output() skb leakage.
 *	2000-10-27	Henner Eisen	MSG_DONTWAIT for fragment allocation.
 *	2000-11-10	Henner Eisen	x25_send_iframe(): re-queued frames
 *					needed cleaned seq-number fields.
 */

#include <linux/socket.h>
#include <linux/kernel.h>
#include <linux/string.h>
#include <linux/skbuff.h>
#include <net/sock.h>
#include <net/x25.h>

static int x25_pacsize_to_bytes(unsigned int pacsize)
{
	int bytes = 1;

	if (!pacsize)
		return 128;

	while (pacsize-- > 0)
		bytes *= 2;

	return bytes;
}

/*
 *	This is where all X.25 information frames pass.
 *
 *      Returns the amount of user data bytes sent on success
 *      or a negative error code on failure.
 */
int x25_output(struct sock *sk, struct sk_buff *skb)
{
	struct sk_buff *skbn;
	unsigned char header[X25_EXT_MIN_LEN];
	int err, frontlen, len;
	int sent=0, noblock = X25_SKB_CB(skb)->flags & MSG_DONTWAIT;
	struct x25_sock *x25 = x25_sk(sk);
	int header_len = x25->neighbour->extended ? X25_EXT_MIN_LEN :
						    X25_STD_MIN_LEN;
	int max_len = x25_pacsize_to_bytes(x25->facilities.pacsize_out);

	if (skb->len - header_len > max_len) {
		/* Save a copy of the Header */
		skb_copy_from_linear_data(skb, header, header_len);
		skb_pull(skb, header_len);

		frontlen = skb_headroom(skb);

		while (skb->len > 0) {
			if ((skbn = sock_alloc_send_skb(sk, frontlen + max_len,
							noblock, &err)) == NULL){
				if (err == -EWOULDBLOCK && noblock){
					kfree_skb(skb);
					return sent;
				}
				SOCK_DEBUG(sk, "x25_output: fragment alloc"
					       " failed, err=%d, %d bytes "
					       "sent\n", err, sent);
				return err;
			}

			skb_reserve(skbn, frontlen);

			len = max_len > skb->len ? skb->len : max_len;

			/* Copy the user data */
			skb_copy_from_linear_data(skb, skb_put(skbn, len), len);
			skb_pull(skb, len);

			/* Duplicate the Header */
			skb_push(skbn, header_len);
			skb_copy_to_linear_data(skbn, header, header_len);

			if (skb->len > 0) {
				if (x25->neighbour->extended)
					skbn->data[3] |= X25_EXT_M_BIT;
				else
					skbn->data[2] |= X25_STD_M_BIT;
			}

			skb_queue_tail(&sk->sk_write_queue, skbn);
			sent += len;
		}

		kfree_skb(skb);
	} else {
		skb_queue_tail(&sk->sk_write_queue, skb);
		sent = skb->len - header_len;
	}
	return sent;
}

/*
 *	This procedure is passed a buffer descriptor for an iframe. It builds
 *	the rest of the control part of the frame and then writes it out.
 */
static void x25_send_iframe(struct sock *sk, struct sk_buff *skb)
{
	struct x25_sock *x25 = x25_sk(sk);

	if (!skb)
		return;

	if (x25->neighbour->extended) {
		skb->data[2]  = (x25->vs << 1) & 0xFE;
		skb->data[3] &= X25_EXT_M_BIT;
		skb->data[3] |= (x25->vr << 1) & 0xFE;
	} else {
		skb->data[2] &= X25_STD_M_BIT;
		skb->data[2] |= (x25->vs << 1) & 0x0E;
		skb->data[2] |= (x25->vr << 5) & 0xE0;
	}

	x25_transmit_link(skb, x25->neighbour);
}

void x25_kick(struct sock *sk)
{
	struct sk_buff *skb, *skbn;
	unsigned short start, end;
	int modulus;
	struct x25_sock *x25 = x25_sk(sk);

	if (x25->state != X25_STATE_3)
		return;

	/*
	 *	Transmit interrupt data.
	 */
	if (!x25->intflag && skb_peek(&x25->interrupt_out_queue) != NULL) {
		x25->intflag = 1;
		skb = skb_dequeue(&x25->interrupt_out_queue);
		x25_transmit_link(skb, x25->neighbour);
	}

	if (x25->condition & X25_COND_PEER_RX_BUSY)
		return;

	if (!skb_peek(&sk->sk_write_queue))
		return;

	modulus = x25->neighbour->extended ? X25_EMODULUS : X25_SMODULUS;

	start   = skb_peek(&x25->ack_queue) ? x25->vs : x25->va;
	end     = (x25->va + x25->facilities.winsize_out) % modulus;

	if (start == end)
		return;

	x25->vs = start;

	/*
	 * Transmit data until either we're out of data to send or
	 * the window is full.
	 */

	skb = skb_dequeue(&sk->sk_write_queue);

	do {
		if ((skbn = skb_clone(skb, GFP_ATOMIC)) == NULL) {
			skb_queue_head(&sk->sk_write_queue, skb);
			break;
		}

		skb_set_owner_w(skbn, sk);

		/*
		 * Transmit the frame copy.
		 */
		x25_send_iframe(sk, skbn);

		x25->vs = (x25->vs + 1) % modulus;

		/*
		 * Requeue the original data frame.
		 */
		skb_queue_tail(&x25->ack_queue, skb);

	} while (x25->vs != end &&
		 (skb = skb_dequeue(&sk->sk_write_queue)) != NULL);

	x25->vl         = x25->vr;
	x25->condition &= ~X25_COND_ACK_PENDING;

	x25_stop_timer(sk);
}

/*
 * The following routines are taken from page 170 of the 7th ARRL Computer
 * Networking Conference paper, as is the whole state machine.
 */

void x25_enquiry_response(struct sock *sk)
{
	struct x25_sock *x25 = x25_sk(sk);

	if (x25->condition & X25_COND_OWN_RX_BUSY)
		x25_write_internal(sk, X25_RNR);
	else
		x25_write_internal(sk, X25_RR);

	x25->vl         = x25->vr;
	x25->condition &= ~X25_COND_ACK_PENDING;

	x25_stop_timer(sk);
}
Commit	Line	Data
1da177e4 LT	1	/*
	2	* X.25 Packet Layer release 002
	3	*
	4	* This is ALPHA test software. This code may break your machine,
	5	* randomly fail to work with new releases, misbehave and/or generally
f8e1d201	6	* screw up. It might even work.
1da177e4 LT	7	*
	8	* This code REQUIRES 2.1.15 or higher
	9	*
	10	* This module:
	11	* This module is free software; you can redistribute it and/or
	12	* modify it under the terms of the GNU General Public License
	13	* as published by the Free Software Foundation; either version
	14	* 2 of the License, or (at your option) any later version.
	15	*
	16	* History
	17	* X.25 001 Jonathan Naylor Started coding.
	18	* X.25 002 Jonathan Naylor New timer architecture.
	19	* 2000-09-04 Henner Eisen Prevented x25_output() skb leakage.
	20	* 2000-10-27 Henner Eisen MSG_DONTWAIT for fragment allocation.
	21	* 2000-11-10 Henner Eisen x25_send_iframe(): re-queued frames
	22	* needed cleaned seq-number fields.
	23	*/
	24
	25	#include <linux/socket.h>
	26	#include <linux/kernel.h>
	27	#include <linux/string.h>
	28	#include <linux/skbuff.h>
	29	#include <net/sock.h>
	30	#include <net/x25.h>
	31
	32	static int x25_pacsize_to_bytes(unsigned int pacsize)
	33	{
	34	int bytes = 1;
	35
	36	if (!pacsize)
	37	return 128;
	38
	39	while (pacsize-- > 0)
	40	bytes *= 2;
	41
	42	return bytes;
	43	}
	44
	45	/*
	46	* This is where all X.25 information frames pass.
	47	*
	48	* Returns the amount of user data bytes sent on success
	49	* or a negative error code on failure.
	50	*/
	51	int x25_output(struct sock sk, struct sk_buff skb)
	52	{
	53	struct sk_buff *skbn;
	54	unsigned char header[X25_EXT_MIN_LEN];
	55	int err, frontlen, len;
	56	int sent=0, noblock = X25_SKB_CB(skb)->flags & MSG_DONTWAIT;
	57	struct x25_sock *x25 = x25_sk(sk);
	58	int header_len = x25->neighbour->extended ? X25_EXT_MIN_LEN :
	59	X25_STD_MIN_LEN;
	60	int max_len = x25_pacsize_to_bytes(x25->facilities.pacsize_out);
	61
	62	if (skb->len - header_len > max_len) {
	63	/* Save a copy of the Header */
d626f62b	64	skb_copy_from_linear_data(skb, header, header_len);
1da177e4 LT	65	skb_pull(skb, header_len);
	66
	67	frontlen = skb_headroom(skb);
	68
	69	while (skb->len > 0) {
	70	if ((skbn = sock_alloc_send_skb(sk, frontlen + max_len,
	71	noblock, &err)) == NULL){
	72	if (err == -EWOULDBLOCK && noblock){
	73	kfree_skb(skb);
	74	return sent;
	75	}
	76	SOCK_DEBUG(sk, "x25_output: fragment alloc"
	77	" failed, err=%d, %d bytes "
	78	"sent\n", err, sent);
	79	return err;
	80	}
f8e1d201	81
1da177e4 LT	82	skb_reserve(skbn, frontlen);
	83
	84	len = max_len > skb->len ? skb->len : max_len;
	85
	86	/* Copy the user data */
d626f62b	87	skb_copy_from_linear_data(skb, skb_put(skbn, len), len);
1da177e4 LT	88	skb_pull(skb, len);
	89
	90	/* Duplicate the Header */
	91	skb_push(skbn, header_len);
27d7ff46	92	skb_copy_to_linear_data(skbn, header, header_len);
1da177e4 LT	93
	94	if (skb->len > 0) {
	95	if (x25->neighbour->extended)
	96	skbn->data[3] \|= X25_EXT_M_BIT;
	97	else
	98	skbn->data[2] \|= X25_STD_M_BIT;
	99	}
	100
	101	skb_queue_tail(&sk->sk_write_queue, skbn);
	102	sent += len;
	103	}
f8e1d201	104
1da177e4 LT	105	kfree_skb(skb);
	106	} else {
	107	skb_queue_tail(&sk->sk_write_queue, skb);
	108	sent = skb->len - header_len;
	109	}
	110	return sent;
	111	}
	112
f8e1d201	113	/*
1da177e4 LT	114	* This procedure is passed a buffer descriptor for an iframe. It builds
	115	* the rest of the control part of the frame and then writes it out.
	116	*/
	117	static void x25_send_iframe(struct sock sk, struct sk_buff skb)
	118	{
	119	struct x25_sock *x25 = x25_sk(sk);
	120
	121	if (!skb)
	122	return;
	123
	124	if (x25->neighbour->extended) {
	125	skb->data[2] = (x25->vs << 1) & 0xFE;
	126	skb->data[3] &= X25_EXT_M_BIT;
	127	skb->data[3] \|= (x25->vr << 1) & 0xFE;
	128	} else {
	129	skb->data[2] &= X25_STD_M_BIT;
	130	skb->data[2] \|= (x25->vs << 1) & 0x0E;
	131	skb->data[2] \|= (x25->vr << 5) & 0xE0;
	132	}
	133
f8e1d201	134	x25_transmit_link(skb, x25->neighbour);
1da177e4 LT	135	}
	136
	137	void x25_kick(struct sock *sk)
	138	{
	139	struct sk_buff skb, skbn;
	140	unsigned short start, end;
	141	int modulus;
	142	struct x25_sock *x25 = x25_sk(sk);
	143
	144	if (x25->state != X25_STATE_3)
	145	return;
	146
	147	/*
	148	* Transmit interrupt data.
	149	*/
	150	if (!x25->intflag && skb_peek(&x25->interrupt_out_queue) != NULL) {
	151	x25->intflag = 1;
	152	skb = skb_dequeue(&x25->interrupt_out_queue);
	153	x25_transmit_link(skb, x25->neighbour);
	154	}
	155
	156	if (x25->condition & X25_COND_PEER_RX_BUSY)
	157	return;
	158
	159	if (!skb_peek(&sk->sk_write_queue))
	160	return;
	161
	162	modulus = x25->neighbour->extended ? X25_EMODULUS : X25_SMODULUS;
	163
	164	start = skb_peek(&x25->ack_queue) ? x25->vs : x25->va;
	165	end = (x25->va + x25->facilities.winsize_out) % modulus;
	166
	167	if (start == end)
	168	return;
	169
	170	x25->vs = start;
	171
	172	/*
	173	* Transmit data until either we're out of data to send or
	174	* the window is full.
	175	*/
	176
	177	skb = skb_dequeue(&sk->sk_write_queue);
	178
	179	do {
	180	if ((skbn = skb_clone(skb, GFP_ATOMIC)) == NULL) {
	181	skb_queue_head(&sk->sk_write_queue, skb);
	182	break;
	183	}
	184
	185	skb_set_owner_w(skbn, sk);
	186
	187	/*
	188	* Transmit the frame copy.
	189	*/
	190	x25_send_iframe(sk, skbn);
	191
	192	x25->vs = (x25->vs + 1) % modulus;
	193
	194	/*
	195	* Requeue the original data frame.
	196	*/
	197	skb_queue_tail(&x25->ack_queue, skb);
	198
199	} while (x25->vs != end &&
200	(skb = skb_dequeue(&sk->sk_write_queue)) != NULL);
201
202	x25->vl = x25->vr;
203	x25->condition &= ~X25_COND_ACK_PENDING;
204
205	x25_stop_timer(sk);
206	}
207
208	/*
209	* The following routines are taken from page 170 of the 7th ARRL Computer
210	* Networking Conference paper, as is the whole state machine.
211	*/
212
213	void x25_enquiry_response(struct sock *sk)
214	{
215	struct x25_sock *x25 = x25_sk(sk);
216
217	if (x25->condition & X25_COND_OWN_RX_BUSY)
218	x25_write_internal(sk, X25_RNR);
219	else
220	x25_write_internal(sk, X25_RR);
221
222	x25->vl = x25->vr;
223	x25->condition &= ~X25_COND_ACK_PENDING;
224
225	x25_stop_timer(sk);
226	}