385 lines
9.2 KiB
C
385 lines
9.2 KiB
C
// SPDX-License-Identifier: GPL-2.0-or-later
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/*
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* X.25 Packet Layer release 002
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*
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* This is ALPHA test software. This code may break your machine,
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* randomly fail to work with new releases, misbehave and/or generally
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* screw up. It might even work.
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*
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* This code REQUIRES 2.1.15 or higher
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*
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* History
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* X.25 001 Jonathan Naylor Started coding.
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* X.25 002 Jonathan Naylor Centralised disconnection processing.
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* mar/20/00 Daniela Squassoni Disabling/enabling of facilities
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* negotiation.
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* jun/24/01 Arnaldo C. Melo use skb_queue_purge, cleanups
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* apr/04/15 Shaun Pereira Fast select with no
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* restriction on response.
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*/
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#define pr_fmt(fmt) "X25: " fmt
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#include <linux/slab.h>
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#include <linux/kernel.h>
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#include <linux/string.h>
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#include <linux/skbuff.h>
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#include <net/sock.h>
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#include <net/tcp_states.h>
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#include <net/x25.h>
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/*
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* This routine purges all of the queues of frames.
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*/
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void x25_clear_queues(struct sock *sk)
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{
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struct x25_sock *x25 = x25_sk(sk);
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skb_queue_purge(&sk->sk_write_queue);
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skb_queue_purge(&x25->ack_queue);
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skb_queue_purge(&x25->interrupt_in_queue);
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skb_queue_purge(&x25->interrupt_out_queue);
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skb_queue_purge(&x25->fragment_queue);
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}
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/*
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* This routine purges the input queue of those frames that have been
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* acknowledged. This replaces the boxes labelled "V(a) <- N(r)" on the
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* SDL diagram.
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*/
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void x25_frames_acked(struct sock *sk, unsigned short nr)
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{
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struct sk_buff *skb;
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struct x25_sock *x25 = x25_sk(sk);
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int modulus = x25->neighbour->extended ? X25_EMODULUS : X25_SMODULUS;
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/*
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* Remove all the ack-ed frames from the ack queue.
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*/
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if (x25->va != nr)
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while (skb_peek(&x25->ack_queue) && x25->va != nr) {
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skb = skb_dequeue(&x25->ack_queue);
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kfree_skb(skb);
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x25->va = (x25->va + 1) % modulus;
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}
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}
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void x25_requeue_frames(struct sock *sk)
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{
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struct sk_buff *skb, *skb_prev = NULL;
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/*
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* Requeue all the un-ack-ed frames on the output queue to be picked
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* up by x25_kick. This arrangement handles the possibility of an empty
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* output queue.
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*/
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while ((skb = skb_dequeue(&x25_sk(sk)->ack_queue)) != NULL) {
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if (!skb_prev)
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skb_queue_head(&sk->sk_write_queue, skb);
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else
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skb_append(skb_prev, skb, &sk->sk_write_queue);
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skb_prev = skb;
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}
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}
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/*
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* Validate that the value of nr is between va and vs. Return true or
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* false for testing.
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*/
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int x25_validate_nr(struct sock *sk, unsigned short nr)
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{
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struct x25_sock *x25 = x25_sk(sk);
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unsigned short vc = x25->va;
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int modulus = x25->neighbour->extended ? X25_EMODULUS : X25_SMODULUS;
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while (vc != x25->vs) {
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if (nr == vc)
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return 1;
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vc = (vc + 1) % modulus;
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}
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return nr == x25->vs ? 1 : 0;
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}
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/*
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* This routine is called when the packet layer internally generates a
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* control frame.
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*/
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void x25_write_internal(struct sock *sk, int frametype)
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{
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struct x25_sock *x25 = x25_sk(sk);
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struct sk_buff *skb;
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unsigned char *dptr;
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unsigned char facilities[X25_MAX_FAC_LEN];
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unsigned char addresses[1 + X25_ADDR_LEN];
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unsigned char lci1, lci2;
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/*
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* Default safe frame size.
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*/
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int len = X25_MAX_L2_LEN + X25_EXT_MIN_LEN;
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/*
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* Adjust frame size.
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*/
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switch (frametype) {
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case X25_CALL_REQUEST:
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len += 1 + X25_ADDR_LEN + X25_MAX_FAC_LEN + X25_MAX_CUD_LEN;
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break;
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case X25_CALL_ACCEPTED: /* fast sel with no restr on resp */
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if (x25->facilities.reverse & 0x80) {
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len += 1 + X25_MAX_FAC_LEN + X25_MAX_CUD_LEN;
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} else {
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len += 1 + X25_MAX_FAC_LEN;
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}
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break;
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case X25_CLEAR_REQUEST:
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case X25_RESET_REQUEST:
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len += 2;
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break;
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case X25_RR:
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case X25_RNR:
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case X25_REJ:
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case X25_CLEAR_CONFIRMATION:
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case X25_INTERRUPT_CONFIRMATION:
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case X25_RESET_CONFIRMATION:
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break;
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default:
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pr_err("invalid frame type %02X\n", frametype);
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return;
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}
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if ((skb = alloc_skb(len, GFP_ATOMIC)) == NULL)
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return;
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/*
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* Space for Ethernet and 802.2 LLC headers.
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*/
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skb_reserve(skb, X25_MAX_L2_LEN);
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/*
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* Make space for the GFI and LCI, and fill them in.
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*/
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dptr = skb_put(skb, 2);
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lci1 = (x25->lci >> 8) & 0x0F;
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lci2 = (x25->lci >> 0) & 0xFF;
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if (x25->neighbour->extended) {
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*dptr++ = lci1 | X25_GFI_EXTSEQ;
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*dptr++ = lci2;
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} else {
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*dptr++ = lci1 | X25_GFI_STDSEQ;
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*dptr++ = lci2;
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}
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/*
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* Now fill in the frame type specific information.
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*/
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switch (frametype) {
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case X25_CALL_REQUEST:
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dptr = skb_put(skb, 1);
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*dptr++ = X25_CALL_REQUEST;
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len = x25_addr_aton(addresses, &x25->dest_addr,
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&x25->source_addr);
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skb_put_data(skb, addresses, len);
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len = x25_create_facilities(facilities,
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&x25->facilities,
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&x25->dte_facilities,
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x25->neighbour->global_facil_mask);
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skb_put_data(skb, facilities, len);
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skb_put_data(skb, x25->calluserdata.cuddata,
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x25->calluserdata.cudlength);
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x25->calluserdata.cudlength = 0;
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break;
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case X25_CALL_ACCEPTED:
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dptr = skb_put(skb, 2);
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*dptr++ = X25_CALL_ACCEPTED;
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*dptr++ = 0x00; /* Address lengths */
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len = x25_create_facilities(facilities,
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&x25->facilities,
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&x25->dte_facilities,
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x25->vc_facil_mask);
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skb_put_data(skb, facilities, len);
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/* fast select with no restriction on response
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allows call user data. Userland must
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ensure it is ours and not theirs */
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if(x25->facilities.reverse & 0x80) {
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skb_put_data(skb,
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x25->calluserdata.cuddata,
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x25->calluserdata.cudlength);
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}
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x25->calluserdata.cudlength = 0;
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break;
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case X25_CLEAR_REQUEST:
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dptr = skb_put(skb, 3);
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*dptr++ = frametype;
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*dptr++ = x25->causediag.cause;
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*dptr++ = x25->causediag.diagnostic;
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break;
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case X25_RESET_REQUEST:
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dptr = skb_put(skb, 3);
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*dptr++ = frametype;
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*dptr++ = 0x00; /* XXX */
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*dptr++ = 0x00; /* XXX */
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break;
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case X25_RR:
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case X25_RNR:
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case X25_REJ:
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if (x25->neighbour->extended) {
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dptr = skb_put(skb, 2);
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*dptr++ = frametype;
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*dptr++ = (x25->vr << 1) & 0xFE;
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} else {
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dptr = skb_put(skb, 1);
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*dptr = frametype;
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*dptr++ |= (x25->vr << 5) & 0xE0;
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}
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break;
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case X25_CLEAR_CONFIRMATION:
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case X25_INTERRUPT_CONFIRMATION:
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case X25_RESET_CONFIRMATION:
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dptr = skb_put(skb, 1);
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*dptr = frametype;
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break;
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}
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x25_transmit_link(skb, x25->neighbour);
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}
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/*
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* Unpick the contents of the passed X.25 Packet Layer frame.
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*/
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int x25_decode(struct sock *sk, struct sk_buff *skb, int *ns, int *nr, int *q,
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int *d, int *m)
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{
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struct x25_sock *x25 = x25_sk(sk);
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unsigned char *frame;
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if (!pskb_may_pull(skb, X25_STD_MIN_LEN))
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return X25_ILLEGAL;
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frame = skb->data;
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*ns = *nr = *q = *d = *m = 0;
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switch (frame[2]) {
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case X25_CALL_REQUEST:
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case X25_CALL_ACCEPTED:
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case X25_CLEAR_REQUEST:
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case X25_CLEAR_CONFIRMATION:
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case X25_INTERRUPT:
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case X25_INTERRUPT_CONFIRMATION:
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case X25_RESET_REQUEST:
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case X25_RESET_CONFIRMATION:
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case X25_RESTART_REQUEST:
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case X25_RESTART_CONFIRMATION:
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case X25_REGISTRATION_REQUEST:
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case X25_REGISTRATION_CONFIRMATION:
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case X25_DIAGNOSTIC:
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return frame[2];
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}
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if (x25->neighbour->extended) {
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if (frame[2] == X25_RR ||
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frame[2] == X25_RNR ||
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frame[2] == X25_REJ) {
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if (!pskb_may_pull(skb, X25_EXT_MIN_LEN))
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return X25_ILLEGAL;
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frame = skb->data;
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*nr = (frame[3] >> 1) & 0x7F;
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return frame[2];
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}
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} else {
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if ((frame[2] & 0x1F) == X25_RR ||
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(frame[2] & 0x1F) == X25_RNR ||
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(frame[2] & 0x1F) == X25_REJ) {
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*nr = (frame[2] >> 5) & 0x07;
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return frame[2] & 0x1F;
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}
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}
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if (x25->neighbour->extended) {
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if ((frame[2] & 0x01) == X25_DATA) {
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if (!pskb_may_pull(skb, X25_EXT_MIN_LEN))
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return X25_ILLEGAL;
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frame = skb->data;
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*q = (frame[0] & X25_Q_BIT) == X25_Q_BIT;
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*d = (frame[0] & X25_D_BIT) == X25_D_BIT;
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*m = (frame[3] & X25_EXT_M_BIT) == X25_EXT_M_BIT;
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*nr = (frame[3] >> 1) & 0x7F;
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*ns = (frame[2] >> 1) & 0x7F;
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return X25_DATA;
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}
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} else {
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if ((frame[2] & 0x01) == X25_DATA) {
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*q = (frame[0] & X25_Q_BIT) == X25_Q_BIT;
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*d = (frame[0] & X25_D_BIT) == X25_D_BIT;
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*m = (frame[2] & X25_STD_M_BIT) == X25_STD_M_BIT;
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*nr = (frame[2] >> 5) & 0x07;
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*ns = (frame[2] >> 1) & 0x07;
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return X25_DATA;
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}
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}
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pr_debug("invalid PLP frame %3ph\n", frame);
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return X25_ILLEGAL;
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}
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void x25_disconnect(struct sock *sk, int reason, unsigned char cause,
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unsigned char diagnostic)
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{
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struct x25_sock *x25 = x25_sk(sk);
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x25_clear_queues(sk);
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x25_stop_timer(sk);
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x25->lci = 0;
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x25->state = X25_STATE_0;
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x25->causediag.cause = cause;
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x25->causediag.diagnostic = diagnostic;
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sk->sk_state = TCP_CLOSE;
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sk->sk_err = reason;
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sk->sk_shutdown |= SEND_SHUTDOWN;
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if (!sock_flag(sk, SOCK_DEAD)) {
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sk->sk_state_change(sk);
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sock_set_flag(sk, SOCK_DEAD);
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}
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if (x25->neighbour) {
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read_lock_bh(&x25_list_lock);
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x25_neigh_put(x25->neighbour);
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x25->neighbour = NULL;
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read_unlock_bh(&x25_list_lock);
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}
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}
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/*
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* Clear an own-rx-busy condition and tell the peer about this, provided
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* that there is a significant amount of free receive buffer space available.
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*/
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void x25_check_rbuf(struct sock *sk)
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{
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struct x25_sock *x25 = x25_sk(sk);
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if (atomic_read(&sk->sk_rmem_alloc) < (sk->sk_rcvbuf >> 1) &&
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(x25->condition & X25_COND_OWN_RX_BUSY)) {
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x25->condition &= ~X25_COND_OWN_RX_BUSY;
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x25->condition &= ~X25_COND_ACK_PENDING;
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x25->vl = x25->vr;
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x25_write_internal(sk, X25_RR);
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x25_stop_timer(sk);
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}
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}
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