/*
* 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 Split from x25_subr.c
* mar/20/00 Daniela Squassoni Disabling/enabling of facilities
* negotiation.
*/
#include <linux/kernel.h>
#include <linux/string.h>
#include <linux/skbuff.h>
#include <net/sock.h>
#include <net/x25.h>
/*
* Parse a set of facilities into the facilities structure. Unrecognised
* facilities are written to the debug log file.
*/
int x25_parse_facilities(struct sk_buff *skb,
struct x25_facilities *facilities,
unsigned long *vc_fac_mask)
{
unsigned char *p = skb->data;
unsigned int len = *p++;
*vc_fac_mask = 0;
while (len > 0) {
switch (*p & X25_FAC_CLASS_MASK) {
case X25_FAC_CLASS_A:
switch (*p) {
case X25_FAC_REVERSE:
facilities->reverse = p[1] & 0x01;
*vc_fac_mask |= X25_MASK_REVERSE;
break;
case X25_FAC_THROUGHPUT:
facilities->throughput = p[1];
*vc_fac_mask |= X25_MASK_THROUGHPUT;
break;
default:
printk(KERN_DEBUG "X.25: unknown facility "
"%02X, value %02X\n",
p[0], p[1]);
break;
}
p += 2;
len -= 2;
break;
case X25_FAC_CLASS_B:
switch (*p) {
case X25_FAC_PACKET_SIZE:
facilities->pacsize_in = p[1];
facilities->pacsize_out = p[2];
*vc_fac_mask |= X25_MASK_PACKET_SIZE;
break;
case X25_FAC_WINDOW_SIZE:
facilities->winsize_in = p[1];
facilities->winsize_out = p[2];
*vc_fac_mask |= X25_MASK_WINDOW_SIZE;
break;
default:
printk(KERN_DEBUG "X.25: unknown facility "
"%02X, values %02X, %02X\n",
p[0], p[1], p[2]);
break;
}
p += 3;
len -= 3;
break;
case X25_FAC_CLASS_C:
printk(KERN_DEBUG "X.25: unknown facility %02X, "
"values %02X, %02X, %02X\n",
p[0], p[1], p[2], p[3]);
p += 4;
len -= 4;
break;
case X25_FAC_CLASS_D:
printk(KERN_DEBUG "X.25: unknown facility %02X, "
"length %d, values %02X, %02X, %02X, %02X\n",
p[0], p[1], p[2], p[3], p[4], p[5]);
len -= p[1] + 2;
p += p[1] + 2;
break;
}
}
return p - skb->data;
}
/*
* Create a set of facilities.
*/
int x25_create_facilities(unsigned char *buffer,
struct x25_facilities *facilities,
unsigned long facil_mask)
{
unsigned char *p = buffer + 1;
int len;
if (!facil_mask) {
/*
* Length of the facilities field in call_req or
* call_accept packets
*/
buffer[0] = 0;
len = 1; /* 1 byte for the length field */
return len;
}
if (facilities->reverse && (facil_mask & X25_MASK_REVERSE)) {
*p++ = X25_FAC_REVERSE;
*p++ = !!facilities->reverse;
}
if (facilities->throughput && (facil_mask & X25_MASK_THROUGHPUT)) {
*p++ = X25_FAC_THROUGHPUT;
*p++ = facilities->throughput;
}
if ((facilities->pacsize_in || facilities->pacsize_out) &&
(facil_mask & X25_MASK_PACKET_SIZE)) {
*p++ = X25_FAC_PACKET_SIZE;
*p++ = facilities->pacsize_in ? : facilities->pacsize_out;
*p++ = facilities->pacsize_out ? : facilities->pacsize_in;
}
if ((facilities->winsize_in || facilities->winsize_out) &&
(facil_mask & X25_MASK_WINDOW_SIZE)) {
*p++ = X25_FAC_WINDOW_SIZE;
*p++ = facilities->winsize_in ? : facilities->winsize_out;
*p++ = facilities->winsize_out ? : facilities->winsize_in;
}
len = p - buffer;
buffer[0] = len - 1;
return len;
}
/*
* Try to reach a compromise on a set of facilities.
*
* The only real problem is with reverse charging.
*/
int x25_negotiate_facilities(struct sk_buff *skb, struct sock *sk,
struct x25_facilities *new)
{
struct x25_sock *x25 = x25_sk(sk);
struct x25_facilities *ours = &x25->facilities;
struct x25_facilities theirs;
int len;
memset(&theirs, 0, sizeof(theirs));
memcpy(new, ours, sizeof(*new));
len = x25_parse_facilities(skb, &theirs, &x25->vc_facil_mask);
/*
* They want reverse charging, we won't accept it.
*/
if (theirs.reverse && ours->reverse) {
SOCK_DEBUG(sk, "X.25: rejecting reverse charging request");
return -1;
}
new->reverse = theirs.reverse;
if (theirs.throughput) {
if (theirs.throughput < ours->throughput) {
SOCK_DEBUG(sk, "X.25: throughput negotiated down");
new->throughput = theirs.throughput;
}
}
if (theirs.pacsize_in && theirs.pacsize_out) {
if (theirs.pacsize_in < ours->pacsize_in) {
SOCK_DEBUG(sk, "X.25: packet size inwards negotiated down");
new->pacsize_in = theirs.pacsize_in;
}
if (theirs.pacsize_out < ours->pacsize_out) {
SOCK_DEBUG(sk, "X.25: packet size outwards negotiated down");
new->pacsize_out = theirs.pacsize_out;
}
}
if (theirs.winsize_in && theirs.winsize_out) {
if (theirs.winsize_in < ours->winsize_in) {
SOCK_DEBUG(sk, "X.25: window size inwards negotiated down");
new->winsize_in = theirs.winsize_in;
}
if (theirs.winsize_out < ours->winsize_out) {
SOCK_DEBUG(sk, "X.25: window size outwards negotiated down");
new->winsize_out = theirs.winsize_out;
}
}
return len;
}
/*
* Limit values of certain facilities according to the capability of the
* currently attached x25 link.
*/
void x25_limit_facilities(struct x25_facilities *facilities,
struct x25_neigh *nb)
{
if (!nb->extended) {
if (facilities->winsize_in > 7) {
printk(KERN_DEBUG "X.25: incoming winsize limited to 7\n");
facilities->winsize_in = 7;
}
if (facilities->winsize_out > 7) {
facilities->winsize_out = 7;
printk( KERN_DEBUG "X.25: outgoing winsize limited to 7\n");
}
}
}
