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/*
* X.25 Packet Layer release 001
*
* 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.
*/
#include <linux/config.h>
#if defined(CONFIG_X25) || defined(CONFIG_X25_MODULE)
#include <linux/errno.h>
#include <linux/types.h>
#include <linux/socket.h>
#include <linux/in.h>
#include <linux/kernel.h>
#include <linux/sched.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 <net/sock.h>
#include <asm/segment.h>
#include <asm/system.h>
#include <linux/fcntl.h>
#include <linux/mm.h>
#include <linux/interrupt.h>
#include <net/x25.h>
static int x25_pacsize_to_bytes(unsigned int pacsize)
{
int bytes = 1;
if (pacsize == 0)
return 128;
while (pacsize-- > 0)
bytes *= 2;
return bytes;
}
/*
* This is where all X.25 information frames pass;
*/
void x25_output(struct sock *sk, struct sk_buff *skb)
{
struct sk_buff *skbn;
unsigned char header[X25_EXT_MIN_LEN];
int err, frontlen, len, header_len, max_len;
header_len = (sk->protinfo.x25->neighbour->extended) ? X25_EXT_MIN_LEN : X25_STD_MIN_LEN;
max_len = x25_pacsize_to_bytes(sk->protinfo.x25->facilities.pacsize_out);
if (skb->len - header_len > max_len) {
/* Save a copy of the Header */
memcpy(header, skb->data, 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, 0, 0, &err)) == NULL)
return;
skb_reserve(skbn, frontlen);
len = (max_len > skb->len) ? skb->len : max_len;
/* Copy the user data */
memcpy(skb_put(skbn, len), skb->data, len);
skb_pull(skb, len);
/* Duplicate the Header */
skb_push(skbn, header_len);
memcpy(skbn->data, header, header_len);
if (skb->len > 0) {
if (sk->protinfo.x25->neighbour->extended)
skbn->data[3] |= X25_EXT_M_BIT;
else
skbn->data[2] |= X25_STD_M_BIT;
}
skb_queue_tail(&sk->write_queue, skbn);
}
kfree_skb(skb, FREE_WRITE);
} else {
skb_queue_tail(&sk->write_queue, skb);
}
}
/*
* 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)
{
if (skb == NULL)
return;
if (sk->protinfo.x25->neighbour->extended) {
skb->data[2] |= (sk->protinfo.x25->vs << 1) & 0xFE;
skb->data[3] |= (sk->protinfo.x25->vr << 1) & 0xFE;
} else {
skb->data[2] |= (sk->protinfo.x25->vs << 1) & 0x0E;
skb->data[2] |= (sk->protinfo.x25->vr << 5) & 0xE0;
}
x25_transmit_link(skb, sk->protinfo.x25->neighbour);
}
void x25_kick(struct sock *sk)
{
struct sk_buff *skb;
unsigned short end;
int modulus;
del_timer(&sk->timer);
/*
* Transmit interrupt data.
*/
if (!sk->protinfo.x25->intflag && skb_peek(&sk->protinfo.x25->interrupt_out_queue) != NULL) {
sk->protinfo.x25->intflag = 1;
skb = skb_dequeue(&sk->protinfo.x25->interrupt_out_queue);
x25_transmit_link(skb, sk->protinfo.x25->neighbour);
}
modulus = (sk->protinfo.x25->neighbour->extended) ? X25_EMODULUS : X25_SMODULUS;
end = (sk->protinfo.x25->va + sk->protinfo.x25->facilities.winsize_out) % modulus;
/*
* Transmit normal stream data.
*/
if (!(sk->protinfo.x25->condition & X25_COND_PEER_RX_BUSY) &&
sk->protinfo.x25->vs != end &&
skb_peek(&sk->write_queue) != NULL) {
/*
* Transmit data until either we're out of data to send or
* the window is full.
*/
skb = skb_dequeue(&sk->write_queue);
do {
/*
* Transmit the frame.
*/
x25_send_iframe(sk, skb);
sk->protinfo.x25->vs = (sk->protinfo.x25->vs + 1) % modulus;
} while (sk->protinfo.x25->vs != end && (skb = skb_dequeue(&sk->write_queue)) != NULL);
sk->protinfo.x25->vl = sk->protinfo.x25->vr;
sk->protinfo.x25->condition &= ~X25_COND_ACK_PENDING;
sk->protinfo.x25->timer = 0;
}
x25_set_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)
{
if (sk->protinfo.x25->condition & X25_COND_OWN_RX_BUSY)
x25_write_internal(sk, X25_RNR);
else
x25_write_internal(sk, X25_RR);
sk->protinfo.x25->vl = sk->protinfo.x25->vr;
sk->protinfo.x25->condition &= ~X25_COND_ACK_PENDING;
sk->protinfo.x25->timer = 0;
}
void x25_check_iframes_acked(struct sock *sk, unsigned short nr)
{
if (sk->protinfo.x25->vs == nr) {
sk->protinfo.x25->va = nr;
} else {
if (sk->protinfo.x25->va != nr) {
sk->protinfo.x25->va = nr;
}
}
}
#endif
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