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linux-stable/net/x25/x25_subr.c
Shaun Pereira cb65d506c3 [X25]: Selective sub-address matching with call user data. 
From: Shaun Pereira <spereira@tusc.com.au>

This is the first (independent of the second) patch of two that I am
working on with x25 on linux (tested with xot on a cisco router).  Details
are as follows.

Current state of module:

A server using the current implementation (2.6.11.7) of the x25 module will
accept a call request/ incoming call packet at the listening x.25 address,
from all callers to that address, as long as NO call user data is present
in the packet header.

If the server needs to choose to accept a particular call request/ incoming
call packet arriving at its listening x25 address, then the kernel has to
allow a match of call user data present in the call request packet with its
own.  This is required when multiple servers listen at the same x25 address
and device interface.  The kernel currently matches ALL call user data, if
present.

Current Changes:

This patch is a follow up to the patch submitted previously by Andrew
Hendry, and allows the user to selectively control the number of octets of
call user data in the call request packet, that the kernel will match.  By
default no call user data is matched, even if call user data is present. 
To allow call user data matching, a cudmatchlength > 0 has to be passed
into the kernel after which the passed number of octets will be matched. 
Otherwise the kernel behavior is exactly as the original implementation.

This patch also ensures that as is normally the case, no call user data
will be present in the Call accepted / call connected packet sent back to
the caller 

Future Changes on next patch:

There are cases however when call user data may be present in the call
accepted packet.  According to the X.25 recommendation (ITU-T 10/96)
section 5.2.3.2 call user data may be present in the call accepted packet
provided the fast select facility is used.  My next patch will include this
fast select utility and the ability to send up to 128 octets call user data
in the call accepted packet provided the fast select facility is used.  I
am currently testing this, again with xot on linux and cisco.  

Signed-off-by: Shaun Pereira <spereira@tusc.com.au>

(With a fix from Alexey Dobriyan <adobriyan@gmail.com>)
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
2005-06-22 22:15:01 -07:00

357 lines
8.7 KiB
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/*
* 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 Centralised disconnection processing.
* mar/20/00 Daniela Squassoni Disabling/enabling of facilities
* negotiation.
* jun/24/01 Arnaldo C. Melo use skb_queue_purge, cleanups
*/
#include <linux/kernel.h>
#include <linux/string.h>
#include <linux/skbuff.h>
#include <net/sock.h>
#include <net/tcp.h>
#include <net/x25.h>
/*
* This routine purges all of the queues of frames.
*/
void x25_clear_queues(struct sock *sk)
{
struct x25_sock *x25 = x25_sk(sk);
skb_queue_purge(&sk->sk_write_queue);
skb_queue_purge(&x25->ack_queue);
skb_queue_purge(&x25->interrupt_in_queue);
skb_queue_purge(&x25->interrupt_out_queue);
skb_queue_purge(&x25->fragment_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 x25_frames_acked(struct sock *sk, unsigned short nr)
{
struct sk_buff *skb;
struct x25_sock *x25 = x25_sk(sk);
int modulus = x25->neighbour->extended ? X25_EMODULUS : X25_SMODULUS;
/*
* Remove all the ack-ed frames from the ack queue.
*/
if (x25->va != nr)
while (skb_peek(&x25->ack_queue) && x25->va != nr) {
skb = skb_dequeue(&x25->ack_queue);
kfree_skb(skb);
x25->va = (x25->va + 1) % modulus;
}
}
void x25_requeue_frames(struct sock *sk)
{
struct sk_buff *skb, *skb_prev = NULL;
/*
* Requeue all the un-ack-ed frames on the output queue to be picked
* up by x25_kick. This arrangement handles the possibility of an empty
* output queue.
*/
while ((skb = skb_dequeue(&x25_sk(sk)->ack_queue)) != NULL) {
if (!skb_prev)
skb_queue_head(&sk->sk_write_queue, skb);
else
skb_append(skb_prev, skb);
skb_prev = skb;
}
}
/*
* Validate that the value of nr is between va and vs. Return true or
* false for testing.
*/
int x25_validate_nr(struct sock *sk, unsigned short nr)
{
struct x25_sock *x25 = x25_sk(sk);
unsigned short vc = x25->va;
int modulus = x25->neighbour->extended ? X25_EMODULUS : X25_SMODULUS;
while (vc != x25->vs) {
if (nr == vc)
return 1;
vc = (vc + 1) % modulus;
}
return nr == x25->vs ? 1 : 0;
}
/*
* This routine is called when the packet layer internally generates a
* control frame.
*/
void x25_write_internal(struct sock *sk, int frametype)
{
struct x25_sock *x25 = x25_sk(sk);
struct sk_buff *skb;
unsigned char *dptr;
unsigned char facilities[X25_MAX_FAC_LEN];
unsigned char addresses[1 + X25_ADDR_LEN];
unsigned char lci1, lci2;
/*
* Default safe frame size.
*/
int len = X25_MAX_L2_LEN + X25_EXT_MIN_LEN;
/*
* Adjust frame size.
*/
switch (frametype) {
case X25_CALL_REQUEST:
len += 1 + X25_ADDR_LEN + X25_MAX_FAC_LEN +
X25_MAX_CUD_LEN;
break;
case X25_CALL_ACCEPTED:
len += 1 + X25_MAX_FAC_LEN + X25_MAX_CUD_LEN;
break;
case X25_CLEAR_REQUEST:
case X25_RESET_REQUEST:
len += 2;
break;
case X25_RR:
case X25_RNR:
case X25_REJ:
case X25_CLEAR_CONFIRMATION:
case X25_INTERRUPT_CONFIRMATION:
case X25_RESET_CONFIRMATION:
break;
default:
printk(KERN_ERR "X.25: invalid frame type %02X\n",
frametype);
return;
}
if ((skb = alloc_skb(len, GFP_ATOMIC)) == NULL)
return;
/*
* Space for Ethernet and 802.2 LLC headers.
*/
skb_reserve(skb, X25_MAX_L2_LEN);
/*
* Make space for the GFI and LCI, and fill them in.
*/
dptr = skb_put(skb, 2);
lci1 = (x25->lci >> 8) & 0x0F;
lci2 = (x25->lci >> 0) & 0xFF;
if (x25->neighbour->extended) {
*dptr++ = lci1 | X25_GFI_EXTSEQ;
*dptr++ = lci2;
} else {
*dptr++ = lci1 | X25_GFI_STDSEQ;
*dptr++ = lci2;
}
/*
* Now fill in the frame type specific information.
*/
switch (frametype) {
case X25_CALL_REQUEST:
dptr = skb_put(skb, 1);
*dptr++ = X25_CALL_REQUEST;
len = x25_addr_aton(addresses, &x25->dest_addr,
&x25->source_addr);
dptr = skb_put(skb, len);
memcpy(dptr, addresses, len);
len = x25_create_facilities(facilities,
&x25->facilities,
x25->neighbour->global_facil_mask);
dptr = skb_put(skb, len);
memcpy(dptr, facilities, len);
dptr = skb_put(skb, x25->calluserdata.cudlength);
memcpy(dptr, x25->calluserdata.cuddata,
x25->calluserdata.cudlength);
x25->calluserdata.cudlength = 0;
break;
case X25_CALL_ACCEPTED:
dptr = skb_put(skb, 2);
*dptr++ = X25_CALL_ACCEPTED;
*dptr++ = 0x00; /* Address lengths */
len = x25_create_facilities(facilities,
&x25->facilities,
x25->vc_facil_mask);
dptr = skb_put(skb, len);
memcpy(dptr, facilities, len);
dptr = skb_put(skb, x25->calluserdata.cudlength);
memcpy(dptr, x25->calluserdata.cuddata,
x25->calluserdata.cudlength);
x25->calluserdata.cudlength = 0;
break;
case X25_CLEAR_REQUEST:
case X25_RESET_REQUEST:
dptr = skb_put(skb, 3);
*dptr++ = frametype;
*dptr++ = 0x00; /* XXX */
*dptr++ = 0x00; /* XXX */
break;
case X25_RR:
case X25_RNR:
case X25_REJ:
if (x25->neighbour->extended) {
dptr = skb_put(skb, 2);
*dptr++ = frametype;
*dptr++ = (x25->vr << 1) & 0xFE;
} else {
dptr = skb_put(skb, 1);
*dptr = frametype;
*dptr++ |= (x25->vr << 5) & 0xE0;
}
break;
case X25_CLEAR_CONFIRMATION:
case X25_INTERRUPT_CONFIRMATION:
case X25_RESET_CONFIRMATION:
dptr = skb_put(skb, 1);
*dptr = frametype;
break;
}
x25_transmit_link(skb, x25->neighbour);
}
/*
* Unpick the contents of the passed X.25 Packet Layer frame.
*/
int x25_decode(struct sock *sk, struct sk_buff *skb, int *ns, int *nr, int *q,
int *d, int *m)
{
struct x25_sock *x25 = x25_sk(sk);
unsigned char *frame = skb->data;
*ns = *nr = *q = *d = *m = 0;
switch (frame[2]) {
case X25_CALL_REQUEST:
case X25_CALL_ACCEPTED:
case X25_CLEAR_REQUEST:
case X25_CLEAR_CONFIRMATION:
case X25_INTERRUPT:
case X25_INTERRUPT_CONFIRMATION:
case X25_RESET_REQUEST:
case X25_RESET_CONFIRMATION:
case X25_RESTART_REQUEST:
case X25_RESTART_CONFIRMATION:
case X25_REGISTRATION_REQUEST:
case X25_REGISTRATION_CONFIRMATION:
case X25_DIAGNOSTIC:
return frame[2];
}
if (x25->neighbour->extended) {
if (frame[2] == X25_RR ||
frame[2] == X25_RNR ||
frame[2] == X25_REJ) {
*nr = (frame[3] >> 1) & 0x7F;
return frame[2];
}
} else {
if ((frame[2] & 0x1F) == X25_RR ||
(frame[2] & 0x1F) == X25_RNR ||
(frame[2] & 0x1F) == X25_REJ) {
*nr = (frame[2] >> 5) & 0x07;
return frame[2] & 0x1F;
}
}
if (x25->neighbour->extended) {
if ((frame[2] & 0x01) == X25_DATA) {
*q = (frame[0] & X25_Q_BIT) == X25_Q_BIT;
*d = (frame[0] & X25_D_BIT) == X25_D_BIT;
*m = (frame[3] & X25_EXT_M_BIT) == X25_EXT_M_BIT;
*nr = (frame[3] >> 1) & 0x7F;
*ns = (frame[2] >> 1) & 0x7F;
return X25_DATA;
}
} else {
if ((frame[2] & 0x01) == X25_DATA) {
*q = (frame[0] & X25_Q_BIT) == X25_Q_BIT;
*d = (frame[0] & X25_D_BIT) == X25_D_BIT;
*m = (frame[2] & X25_STD_M_BIT) == X25_STD_M_BIT;
*nr = (frame[2] >> 5) & 0x07;
*ns = (frame[2] >> 1) & 0x07;
return X25_DATA;
}
}
printk(KERN_DEBUG "X.25: invalid PLP frame %02X %02X %02X\n",
frame[0], frame[1], frame[2]);
return X25_ILLEGAL;
}
void x25_disconnect(struct sock *sk, int reason, unsigned char cause,
unsigned char diagnostic)
{
struct x25_sock *x25 = x25_sk(sk);
x25_clear_queues(sk);
x25_stop_timer(sk);
x25->lci = 0;
x25->state = X25_STATE_0;
x25->causediag.cause = cause;
x25->causediag.diagnostic = diagnostic;
sk->sk_state = TCP_CLOSE;
sk->sk_err = reason;
sk->sk_shutdown |= SEND_SHUTDOWN;
if (!sock_flag(sk, SOCK_DEAD)) {
sk->sk_state_change(sk);
sock_set_flag(sk, SOCK_DEAD);
}
}
/*
* Clear an own-rx-busy condition and tell the peer about this, provided
* that there is a significant amount of free receive buffer space available.
*/
void x25_check_rbuf(struct sock *sk)
{
struct x25_sock *x25 = x25_sk(sk);
if (atomic_read(&sk->sk_rmem_alloc) < (sk->sk_rcvbuf / 2) &&
(x25->condition & X25_COND_OWN_RX_BUSY)) {
x25->condition &= ~X25_COND_OWN_RX_BUSY;
x25->condition &= ~X25_COND_ACK_PENDING;
x25->vl = x25->vr;
x25_write_internal(sk, X25_RR);
x25_stop_timer(sk);
}
}
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