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350 lines
8.9 KiB
350 lines
8.9 KiB
// 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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