351 lines
8.9 KiB
C
351 lines
8.9 KiB
C
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// 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 Split from x25_subr.c
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* mar/20/00 Daniela Squassoni Disabling/enabling of facilities
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* negotiation.
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* apr/14/05 Shaun Pereira - Allow fast select with no restriction
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* on response.
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*/
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#define pr_fmt(fmt) "X25: " fmt
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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/x25.h>
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/**
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* x25_parse_facilities - Parse facilities from skb into the facilities structs
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*
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* @skb: sk_buff to parse
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* @facilities: Regular facilities, updated as facilities are found
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* @dte_facs: ITU DTE facilities, updated as DTE facilities are found
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* @vc_fac_mask: mask is updated with all facilities found
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*
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* Return codes:
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* -1 - Parsing error, caller should drop call and clean up
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* 0 - Parse OK, this skb has no facilities
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* >0 - Parse OK, returns the length of the facilities header
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*
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*/
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int x25_parse_facilities(struct sk_buff *skb, struct x25_facilities *facilities,
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struct x25_dte_facilities *dte_facs, unsigned long *vc_fac_mask)
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{
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unsigned char *p;
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unsigned int len;
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*vc_fac_mask = 0;
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/*
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* The kernel knows which facilities were set on an incoming call but
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* currently this information is not available to userspace. Here we
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* give userspace who read incoming call facilities 0 length to indicate
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* it wasn't set.
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*/
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dte_facs->calling_len = 0;
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dte_facs->called_len = 0;
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memset(dte_facs->called_ae, '\0', sizeof(dte_facs->called_ae));
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memset(dte_facs->calling_ae, '\0', sizeof(dte_facs->calling_ae));
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if (!pskb_may_pull(skb, 1))
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return 0;
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len = skb->data[0];
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if (!pskb_may_pull(skb, 1 + len))
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return -1;
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p = skb->data + 1;
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while (len > 0) {
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switch (*p & X25_FAC_CLASS_MASK) {
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case X25_FAC_CLASS_A:
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if (len < 2)
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return -1;
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switch (*p) {
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case X25_FAC_REVERSE:
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if((p[1] & 0x81) == 0x81) {
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facilities->reverse = p[1] & 0x81;
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*vc_fac_mask |= X25_MASK_REVERSE;
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break;
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}
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if((p[1] & 0x01) == 0x01) {
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facilities->reverse = p[1] & 0x01;
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*vc_fac_mask |= X25_MASK_REVERSE;
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break;
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}
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if((p[1] & 0x80) == 0x80) {
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facilities->reverse = p[1] & 0x80;
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*vc_fac_mask |= X25_MASK_REVERSE;
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break;
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}
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if(p[1] == 0x00) {
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facilities->reverse
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= X25_DEFAULT_REVERSE;
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*vc_fac_mask |= X25_MASK_REVERSE;
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break;
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}
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fallthrough;
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case X25_FAC_THROUGHPUT:
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facilities->throughput = p[1];
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*vc_fac_mask |= X25_MASK_THROUGHPUT;
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break;
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case X25_MARKER:
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break;
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default:
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pr_debug("unknown facility "
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"%02X, value %02X\n",
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p[0], p[1]);
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break;
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}
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p += 2;
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len -= 2;
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break;
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case X25_FAC_CLASS_B:
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if (len < 3)
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return -1;
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switch (*p) {
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case X25_FAC_PACKET_SIZE:
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facilities->pacsize_in = p[1];
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facilities->pacsize_out = p[2];
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*vc_fac_mask |= X25_MASK_PACKET_SIZE;
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break;
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case X25_FAC_WINDOW_SIZE:
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facilities->winsize_in = p[1];
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facilities->winsize_out = p[2];
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*vc_fac_mask |= X25_MASK_WINDOW_SIZE;
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break;
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default:
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pr_debug("unknown facility "
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"%02X, values %02X, %02X\n",
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p[0], p[1], p[2]);
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break;
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}
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p += 3;
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len -= 3;
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break;
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case X25_FAC_CLASS_C:
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if (len < 4)
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return -1;
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pr_debug("unknown facility %02X, "
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"values %02X, %02X, %02X\n",
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p[0], p[1], p[2], p[3]);
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p += 4;
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len -= 4;
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break;
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case X25_FAC_CLASS_D:
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if (len < p[1] + 2)
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return -1;
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switch (*p) {
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case X25_FAC_CALLING_AE:
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if (p[1] > X25_MAX_DTE_FACIL_LEN || p[1] <= 1)
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return -1;
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if (p[2] > X25_MAX_AE_LEN)
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return -1;
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dte_facs->calling_len = p[2];
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memcpy(dte_facs->calling_ae, &p[3], p[1] - 1);
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*vc_fac_mask |= X25_MASK_CALLING_AE;
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break;
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case X25_FAC_CALLED_AE:
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if (p[1] > X25_MAX_DTE_FACIL_LEN || p[1] <= 1)
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return -1;
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if (p[2] > X25_MAX_AE_LEN)
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return -1;
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dte_facs->called_len = p[2];
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memcpy(dte_facs->called_ae, &p[3], p[1] - 1);
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*vc_fac_mask |= X25_MASK_CALLED_AE;
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break;
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default:
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pr_debug("unknown facility %02X,"
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"length %d\n", p[0], p[1]);
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break;
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}
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len -= p[1] + 2;
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p += p[1] + 2;
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break;
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}
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}
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return p - skb->data;
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}
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/*
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* Create a set of facilities.
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*/
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int x25_create_facilities(unsigned char *buffer,
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struct x25_facilities *facilities,
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struct x25_dte_facilities *dte_facs, unsigned long facil_mask)
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{
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unsigned char *p = buffer + 1;
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int len;
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if (!facil_mask) {
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/*
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* Length of the facilities field in call_req or
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* call_accept packets
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*/
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buffer[0] = 0;
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len = 1; /* 1 byte for the length field */
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return len;
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}
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if (facilities->reverse && (facil_mask & X25_MASK_REVERSE)) {
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*p++ = X25_FAC_REVERSE;
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*p++ = facilities->reverse;
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}
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if (facilities->throughput && (facil_mask & X25_MASK_THROUGHPUT)) {
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*p++ = X25_FAC_THROUGHPUT;
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*p++ = facilities->throughput;
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}
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if ((facilities->pacsize_in || facilities->pacsize_out) &&
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(facil_mask & X25_MASK_PACKET_SIZE)) {
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*p++ = X25_FAC_PACKET_SIZE;
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*p++ = facilities->pacsize_in ? : facilities->pacsize_out;
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*p++ = facilities->pacsize_out ? : facilities->pacsize_in;
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}
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if ((facilities->winsize_in || facilities->winsize_out) &&
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(facil_mask & X25_MASK_WINDOW_SIZE)) {
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*p++ = X25_FAC_WINDOW_SIZE;
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*p++ = facilities->winsize_in ? : facilities->winsize_out;
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*p++ = facilities->winsize_out ? : facilities->winsize_in;
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}
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if (facil_mask & (X25_MASK_CALLING_AE|X25_MASK_CALLED_AE)) {
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*p++ = X25_MARKER;
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*p++ = X25_DTE_SERVICES;
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}
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if (dte_facs->calling_len && (facil_mask & X25_MASK_CALLING_AE)) {
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unsigned int bytecount = (dte_facs->calling_len + 1) >> 1;
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*p++ = X25_FAC_CALLING_AE;
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*p++ = 1 + bytecount;
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*p++ = dte_facs->calling_len;
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memcpy(p, dte_facs->calling_ae, bytecount);
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p += bytecount;
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}
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if (dte_facs->called_len && (facil_mask & X25_MASK_CALLED_AE)) {
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unsigned int bytecount = (dte_facs->called_len % 2) ?
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dte_facs->called_len / 2 + 1 :
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dte_facs->called_len / 2;
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*p++ = X25_FAC_CALLED_AE;
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*p++ = 1 + bytecount;
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*p++ = dte_facs->called_len;
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memcpy(p, dte_facs->called_ae, bytecount);
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p+=bytecount;
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}
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len = p - buffer;
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buffer[0] = len - 1;
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return len;
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}
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/*
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* Try to reach a compromise on a set of facilities.
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*
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* The only real problem is with reverse charging.
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*/
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int x25_negotiate_facilities(struct sk_buff *skb, struct sock *sk,
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struct x25_facilities *new, struct x25_dte_facilities *dte)
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{
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struct x25_sock *x25 = x25_sk(sk);
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struct x25_facilities *ours = &x25->facilities;
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struct x25_facilities theirs;
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int len;
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memset(&theirs, 0, sizeof(theirs));
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memcpy(new, ours, sizeof(*new));
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memset(dte, 0, sizeof(*dte));
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len = x25_parse_facilities(skb, &theirs, dte, &x25->vc_facil_mask);
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if (len < 0)
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return len;
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/*
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* They want reverse charging, we won't accept it.
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*/
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if ((theirs.reverse & 0x01 ) && (ours->reverse & 0x01)) {
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SOCK_DEBUG(sk, "X.25: rejecting reverse charging request\n");
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return -1;
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}
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new->reverse = theirs.reverse;
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if (theirs.throughput) {
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int theirs_in = theirs.throughput & 0x0f;
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int theirs_out = theirs.throughput & 0xf0;
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int ours_in = ours->throughput & 0x0f;
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int ours_out = ours->throughput & 0xf0;
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if (!ours_in || theirs_in < ours_in) {
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SOCK_DEBUG(sk, "X.25: inbound throughput negotiated\n");
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new->throughput = (new->throughput & 0xf0) | theirs_in;
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}
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if (!ours_out || theirs_out < ours_out) {
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SOCK_DEBUG(sk,
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"X.25: outbound throughput negotiated\n");
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new->throughput = (new->throughput & 0x0f) | theirs_out;
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}
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}
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if (theirs.pacsize_in && theirs.pacsize_out) {
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if (theirs.pacsize_in < ours->pacsize_in) {
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SOCK_DEBUG(sk, "X.25: packet size inwards negotiated down\n");
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new->pacsize_in = theirs.pacsize_in;
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}
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if (theirs.pacsize_out < ours->pacsize_out) {
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SOCK_DEBUG(sk, "X.25: packet size outwards negotiated down\n");
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new->pacsize_out = theirs.pacsize_out;
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}
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}
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if (theirs.winsize_in && theirs.winsize_out) {
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if (theirs.winsize_in < ours->winsize_in) {
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SOCK_DEBUG(sk, "X.25: window size inwards negotiated down\n");
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new->winsize_in = theirs.winsize_in;
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}
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if (theirs.winsize_out < ours->winsize_out) {
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SOCK_DEBUG(sk, "X.25: window size outwards negotiated down\n");
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new->winsize_out = theirs.winsize_out;
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}
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}
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return len;
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}
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/*
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* Limit values of certain facilities according to the capability of the
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* currently attached x25 link.
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*/
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void x25_limit_facilities(struct x25_facilities *facilities,
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struct x25_neigh *nb)
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{
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if (!nb->extended) {
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if (facilities->winsize_in > 7) {
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pr_debug("incoming winsize limited to 7\n");
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facilities->winsize_in = 7;
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}
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if (facilities->winsize_out > 7) {
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facilities->winsize_out = 7;
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pr_debug("outgoing winsize limited to 7\n");
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}
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}
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}
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