Viewing file:  x25_out.c (5.84 KB) -rw-r--r--
Select action/file-type:
 (+) |  (+) |  (+) | Code (+) | Session (+) |  (+) | SDB (+) |  (+) |  (+) |  (+) |  (+) |  (+) |
/*
* 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/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.
*
* 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, header_len, max_len;
int sent=0, noblock = X25_SKB_CB(skb)->flags & MSG_DONTWAIT;
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, noblock, &err)) == NULL){
if(err == -EWOULDBLOCK && noblock){
kfree_skb(skb);
return sent;
}
SOCK_DEBUG(sk, "x25_output: fragment allocation 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 */
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);
sent += len;
}
kfree_skb(skb);
} else {
skb_queue_tail(&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)
{
if (skb == NULL)
return;
if (sk->protinfo.x25->neighbour->extended) {
skb->data[2] = (sk->protinfo.x25->vs << 1) & 0xFE;
skb->data[3] &= X25_EXT_M_BIT;
skb->data[3] |= (sk->protinfo.x25->vr << 1) & 0xFE;
} else {
skb->data[2] &= X25_STD_M_BIT;
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, *skbn;
unsigned short start, end;
int modulus;
if (sk->protinfo.x25->state != X25_STATE_3)
return;
/*
* 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);
}
if (sk->protinfo.x25->condition & X25_COND_PEER_RX_BUSY)
return;
if (skb_peek(&sk->write_queue) == NULL)
return;
modulus = (sk->protinfo.x25->neighbour->extended) ? X25_EMODULUS : X25_SMODULUS;
start = (skb_peek(&sk->protinfo.x25->ack_queue) == NULL) ? sk->protinfo.x25->va : sk->protinfo.x25->vs;
end = (sk->protinfo.x25->va + sk->protinfo.x25->facilities.winsize_out) % modulus;
if (start == end)
return;
sk->protinfo.x25->vs = start;
/*
* Transmit data until either we're out of data to send or
* the window is full.
*/
skb = skb_dequeue(&sk->write_queue);
do {
if ((skbn = skb_clone(skb, GFP_ATOMIC)) == NULL) {
skb_queue_head(&sk->write_queue, skb);
break;
}
skb_set_owner_w(skbn, sk);
/*
* Transmit the frame copy.
*/
x25_send_iframe(sk, skbn);
sk->protinfo.x25->vs = (sk->protinfo.x25->vs + 1) % modulus;
/*
* Requeue the original data frame.
*/
skb_queue_tail(&sk->protinfo.x25->ack_queue, skb);
} 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;
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)
{
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;
x25_stop_timer(sk);
}
|