1 /*
2 * X.25 Packet Layer release 002
3 *
4 * This is ALPHA test software. This code may break your machine,
5 * randomly fail to work with new releases, misbehave and/or generally
6 * screw up. It might even work.
7 *
8 * This code REQUIRES 2.1.15 or higher
9 *
10 * This module:
11 * This module is free software; you can redistribute it and/or
12 * modify it under the terms of the GNU General Public License
13 * as published by the Free Software Foundation; either version
14 * 2 of the License, or (at your option) any later version.
15 *
16 * History
17 * X.25 001 Split from x25_subr.c
18 * mar/20/00 Daniela Squassoni Disabling/enabling of facilities
19 * negotiation.
20 * apr/14/05 Shaun Pereira - Allow fast select with no restriction
21 * on response.
22 */
23
24 #include <linux/kernel.h>
25 #include <linux/string.h>
26 #include <linux/skbuff.h>
27 #include <net/sock.h>
28 #include <net/x25.h>
29
30 /**
31 * x25_parse_facilities - Parse facilities from skb into the facilities structs
32 *
33 * @skb: sk_buff to parse
34 * @facilities: Regular facilities, updated as facilities are found
35 * @dte_facs: ITU DTE facilities, updated as DTE facilities are found
36 * @vc_fac_mask: mask is updated with all facilities found
37 *
38 * Return codes:
39 * -1 - Parsing error, caller should drop call and clean up
40 * 0 - Parse OK, this skb has no facilities
41 * >0 - Parse OK, returns the length of the facilities header
42 *
43 */
x25_parse_facilities(struct sk_buff * skb,struct x25_facilities * facilities,struct x25_dte_facilities * dte_facs,unsigned long * vc_fac_mask)44 int x25_parse_facilities(struct sk_buff *skb, struct x25_facilities *facilities,
45 struct x25_dte_facilities *dte_facs, unsigned long *vc_fac_mask)
46 {
47 unsigned char *p;
48 unsigned int len;
49
50 *vc_fac_mask = 0;
51
52 /*
53 * The kernel knows which facilities were set on an incoming call but
54 * currently this information is not available to userspace. Here we
55 * give userspace who read incoming call facilities 0 length to indicate
56 * it wasn't set.
57 */
58 dte_facs->calling_len = 0;
59 dte_facs->called_len = 0;
60 memset(dte_facs->called_ae, '\0', sizeof(dte_facs->called_ae));
61 memset(dte_facs->calling_ae, '\0', sizeof(dte_facs->calling_ae));
62
63 if (!pskb_may_pull(skb, 1))
64 return 0;
65
66 len = skb->data[0];
67
68 if (!pskb_may_pull(skb, 1 + len))
69 return -1;
70
71 p = skb->data + 1;
72
73 while (len > 0) {
74 switch (*p & X25_FAC_CLASS_MASK) {
75 case X25_FAC_CLASS_A:
76 if (len < 2)
77 return -1;
78 switch (*p) {
79 case X25_FAC_REVERSE:
80 if((p[1] & 0x81) == 0x81) {
81 facilities->reverse = p[1] & 0x81;
82 *vc_fac_mask |= X25_MASK_REVERSE;
83 break;
84 }
85
86 if((p[1] & 0x01) == 0x01) {
87 facilities->reverse = p[1] & 0x01;
88 *vc_fac_mask |= X25_MASK_REVERSE;
89 break;
90 }
91
92 if((p[1] & 0x80) == 0x80) {
93 facilities->reverse = p[1] & 0x80;
94 *vc_fac_mask |= X25_MASK_REVERSE;
95 break;
96 }
97
98 if(p[1] == 0x00) {
99 facilities->reverse
100 = X25_DEFAULT_REVERSE;
101 *vc_fac_mask |= X25_MASK_REVERSE;
102 break;
103 }
104
105 case X25_FAC_THROUGHPUT:
106 facilities->throughput = p[1];
107 *vc_fac_mask |= X25_MASK_THROUGHPUT;
108 break;
109 case X25_MARKER:
110 break;
111 default:
112 printk(KERN_DEBUG "X.25: unknown facility "
113 "%02X, value %02X\n",
114 p[0], p[1]);
115 break;
116 }
117 p += 2;
118 len -= 2;
119 break;
120 case X25_FAC_CLASS_B:
121 if (len < 3)
122 return -1;
123 switch (*p) {
124 case X25_FAC_PACKET_SIZE:
125 facilities->pacsize_in = p[1];
126 facilities->pacsize_out = p[2];
127 *vc_fac_mask |= X25_MASK_PACKET_SIZE;
128 break;
129 case X25_FAC_WINDOW_SIZE:
130 facilities->winsize_in = p[1];
131 facilities->winsize_out = p[2];
132 *vc_fac_mask |= X25_MASK_WINDOW_SIZE;
133 break;
134 default:
135 printk(KERN_DEBUG "X.25: unknown facility "
136 "%02X, values %02X, %02X\n",
137 p[0], p[1], p[2]);
138 break;
139 }
140 p += 3;
141 len -= 3;
142 break;
143 case X25_FAC_CLASS_C:
144 if (len < 4)
145 return -1;
146 printk(KERN_DEBUG "X.25: unknown facility %02X, "
147 "values %02X, %02X, %02X\n",
148 p[0], p[1], p[2], p[3]);
149 p += 4;
150 len -= 4;
151 break;
152 case X25_FAC_CLASS_D:
153 if (len < p[1] + 2)
154 return -1;
155 switch (*p) {
156 case X25_FAC_CALLING_AE:
157 if (p[1] > X25_MAX_DTE_FACIL_LEN || p[1] <= 1)
158 return -1;
159 dte_facs->calling_len = p[2];
160 memcpy(dte_facs->calling_ae, &p[3], p[1] - 1);
161 *vc_fac_mask |= X25_MASK_CALLING_AE;
162 break;
163 case X25_FAC_CALLED_AE:
164 if (p[1] > X25_MAX_DTE_FACIL_LEN || p[1] <= 1)
165 return -1;
166 dte_facs->called_len = p[2];
167 memcpy(dte_facs->called_ae, &p[3], p[1] - 1);
168 *vc_fac_mask |= X25_MASK_CALLED_AE;
169 break;
170 default:
171 printk(KERN_DEBUG "X.25: unknown facility %02X,"
172 "length %d\n", p[0], p[1]);
173 break;
174 }
175 len -= p[1] + 2;
176 p += p[1] + 2;
177 break;
178 }
179 }
180
181 return p - skb->data;
182 }
183
184 /*
185 * Create a set of facilities.
186 */
x25_create_facilities(unsigned char * buffer,struct x25_facilities * facilities,struct x25_dte_facilities * dte_facs,unsigned long facil_mask)187 int x25_create_facilities(unsigned char *buffer,
188 struct x25_facilities *facilities,
189 struct x25_dte_facilities *dte_facs, unsigned long facil_mask)
190 {
191 unsigned char *p = buffer + 1;
192 int len;
193
194 if (!facil_mask) {
195 /*
196 * Length of the facilities field in call_req or
197 * call_accept packets
198 */
199 buffer[0] = 0;
200 len = 1; /* 1 byte for the length field */
201 return len;
202 }
203
204 if (facilities->reverse && (facil_mask & X25_MASK_REVERSE)) {
205 *p++ = X25_FAC_REVERSE;
206 *p++ = facilities->reverse;
207 }
208
209 if (facilities->throughput && (facil_mask & X25_MASK_THROUGHPUT)) {
210 *p++ = X25_FAC_THROUGHPUT;
211 *p++ = facilities->throughput;
212 }
213
214 if ((facilities->pacsize_in || facilities->pacsize_out) &&
215 (facil_mask & X25_MASK_PACKET_SIZE)) {
216 *p++ = X25_FAC_PACKET_SIZE;
217 *p++ = facilities->pacsize_in ? : facilities->pacsize_out;
218 *p++ = facilities->pacsize_out ? : facilities->pacsize_in;
219 }
220
221 if ((facilities->winsize_in || facilities->winsize_out) &&
222 (facil_mask & X25_MASK_WINDOW_SIZE)) {
223 *p++ = X25_FAC_WINDOW_SIZE;
224 *p++ = facilities->winsize_in ? : facilities->winsize_out;
225 *p++ = facilities->winsize_out ? : facilities->winsize_in;
226 }
227
228 if (facil_mask & (X25_MASK_CALLING_AE|X25_MASK_CALLED_AE)) {
229 *p++ = X25_MARKER;
230 *p++ = X25_DTE_SERVICES;
231 }
232
233 if (dte_facs->calling_len && (facil_mask & X25_MASK_CALLING_AE)) {
234 unsigned int bytecount = (dte_facs->calling_len + 1) >> 1;
235 *p++ = X25_FAC_CALLING_AE;
236 *p++ = 1 + bytecount;
237 *p++ = dte_facs->calling_len;
238 memcpy(p, dte_facs->calling_ae, bytecount);
239 p += bytecount;
240 }
241
242 if (dte_facs->called_len && (facil_mask & X25_MASK_CALLED_AE)) {
243 unsigned int bytecount = (dte_facs->called_len % 2) ?
244 dte_facs->called_len / 2 + 1 :
245 dte_facs->called_len / 2;
246 *p++ = X25_FAC_CALLED_AE;
247 *p++ = 1 + bytecount;
248 *p++ = dte_facs->called_len;
249 memcpy(p, dte_facs->called_ae, bytecount);
250 p+=bytecount;
251 }
252
253 len = p - buffer;
254 buffer[0] = len - 1;
255
256 return len;
257 }
258
259 /*
260 * Try to reach a compromise on a set of facilities.
261 *
262 * The only real problem is with reverse charging.
263 */
x25_negotiate_facilities(struct sk_buff * skb,struct sock * sk,struct x25_facilities * new,struct x25_dte_facilities * dte)264 int x25_negotiate_facilities(struct sk_buff *skb, struct sock *sk,
265 struct x25_facilities *new, struct x25_dte_facilities *dte)
266 {
267 struct x25_sock *x25 = x25_sk(sk);
268 struct x25_facilities *ours = &x25->facilities;
269 struct x25_facilities theirs;
270 int len;
271
272 memset(&theirs, 0, sizeof(theirs));
273 memcpy(new, ours, sizeof(*new));
274
275 len = x25_parse_facilities(skb, &theirs, dte, &x25->vc_facil_mask);
276 if (len < 0)
277 return len;
278
279 /*
280 * They want reverse charging, we won't accept it.
281 */
282 if ((theirs.reverse & 0x01 ) && (ours->reverse & 0x01)) {
283 SOCK_DEBUG(sk, "X.25: rejecting reverse charging request\n");
284 return -1;
285 }
286
287 new->reverse = theirs.reverse;
288
289 if (theirs.throughput) {
290 int theirs_in = theirs.throughput & 0x0f;
291 int theirs_out = theirs.throughput & 0xf0;
292 int ours_in = ours->throughput & 0x0f;
293 int ours_out = ours->throughput & 0xf0;
294 if (!ours_in || theirs_in < ours_in) {
295 SOCK_DEBUG(sk, "X.25: inbound throughput negotiated\n");
296 new->throughput = (new->throughput & 0xf0) | theirs_in;
297 }
298 if (!ours_out || theirs_out < ours_out) {
299 SOCK_DEBUG(sk,
300 "X.25: outbound throughput negotiated\n");
301 new->throughput = (new->throughput & 0x0f) | theirs_out;
302 }
303 }
304
305 if (theirs.pacsize_in && theirs.pacsize_out) {
306 if (theirs.pacsize_in < ours->pacsize_in) {
307 SOCK_DEBUG(sk, "X.25: packet size inwards negotiated down\n");
308 new->pacsize_in = theirs.pacsize_in;
309 }
310 if (theirs.pacsize_out < ours->pacsize_out) {
311 SOCK_DEBUG(sk, "X.25: packet size outwards negotiated down\n");
312 new->pacsize_out = theirs.pacsize_out;
313 }
314 }
315
316 if (theirs.winsize_in && theirs.winsize_out) {
317 if (theirs.winsize_in < ours->winsize_in) {
318 SOCK_DEBUG(sk, "X.25: window size inwards negotiated down\n");
319 new->winsize_in = theirs.winsize_in;
320 }
321 if (theirs.winsize_out < ours->winsize_out) {
322 SOCK_DEBUG(sk, "X.25: window size outwards negotiated down\n");
323 new->winsize_out = theirs.winsize_out;
324 }
325 }
326
327 return len;
328 }
329
330 /*
331 * Limit values of certain facilities according to the capability of the
332 * currently attached x25 link.
333 */
x25_limit_facilities(struct x25_facilities * facilities,struct x25_neigh * nb)334 void x25_limit_facilities(struct x25_facilities *facilities,
335 struct x25_neigh *nb)
336 {
337
338 if (!nb->extended) {
339 if (facilities->winsize_in > 7) {
340 printk(KERN_DEBUG "X.25: incoming winsize limited to 7\n");
341 facilities->winsize_in = 7;
342 }
343 if (facilities->winsize_out > 7) {
344 facilities->winsize_out = 7;
345 printk( KERN_DEBUG "X.25: outgoing winsize limited to 7\n");
346 }
347 }
348 }
349