Root/
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 facilites, 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 | */ |
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 = skb->data; |
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 (skb->len < 1) |
64 | return 0; |
65 | |
66 | len = *p++; |
67 | |
68 | if (len >= skb->len) |
69 | return -1; |
70 | |
71 | while (len > 0) { |
72 | switch (*p & X25_FAC_CLASS_MASK) { |
73 | case X25_FAC_CLASS_A: |
74 | if (len < 2) |
75 | return -1; |
76 | switch (*p) { |
77 | case X25_FAC_REVERSE: |
78 | if((p[1] & 0x81) == 0x81) { |
79 | facilities->reverse = p[1] & 0x81; |
80 | *vc_fac_mask |= X25_MASK_REVERSE; |
81 | break; |
82 | } |
83 | |
84 | if((p[1] & 0x01) == 0x01) { |
85 | facilities->reverse = p[1] & 0x01; |
86 | *vc_fac_mask |= X25_MASK_REVERSE; |
87 | break; |
88 | } |
89 | |
90 | if((p[1] & 0x80) == 0x80) { |
91 | facilities->reverse = p[1] & 0x80; |
92 | *vc_fac_mask |= X25_MASK_REVERSE; |
93 | break; |
94 | } |
95 | |
96 | if(p[1] == 0x00) { |
97 | facilities->reverse |
98 | = X25_DEFAULT_REVERSE; |
99 | *vc_fac_mask |= X25_MASK_REVERSE; |
100 | break; |
101 | } |
102 | |
103 | case X25_FAC_THROUGHPUT: |
104 | facilities->throughput = p[1]; |
105 | *vc_fac_mask |= X25_MASK_THROUGHPUT; |
106 | break; |
107 | case X25_MARKER: |
108 | break; |
109 | default: |
110 | printk(KERN_DEBUG "X.25: unknown facility " |
111 | "%02X, value %02X\n", |
112 | p[0], p[1]); |
113 | break; |
114 | } |
115 | p += 2; |
116 | len -= 2; |
117 | break; |
118 | case X25_FAC_CLASS_B: |
119 | if (len < 3) |
120 | return -1; |
121 | switch (*p) { |
122 | case X25_FAC_PACKET_SIZE: |
123 | facilities->pacsize_in = p[1]; |
124 | facilities->pacsize_out = p[2]; |
125 | *vc_fac_mask |= X25_MASK_PACKET_SIZE; |
126 | break; |
127 | case X25_FAC_WINDOW_SIZE: |
128 | facilities->winsize_in = p[1]; |
129 | facilities->winsize_out = p[2]; |
130 | *vc_fac_mask |= X25_MASK_WINDOW_SIZE; |
131 | break; |
132 | default: |
133 | printk(KERN_DEBUG "X.25: unknown facility " |
134 | "%02X, values %02X, %02X\n", |
135 | p[0], p[1], p[2]); |
136 | break; |
137 | } |
138 | p += 3; |
139 | len -= 3; |
140 | break; |
141 | case X25_FAC_CLASS_C: |
142 | if (len < 4) |
143 | return -1; |
144 | printk(KERN_DEBUG "X.25: unknown facility %02X, " |
145 | "values %02X, %02X, %02X\n", |
146 | p[0], p[1], p[2], p[3]); |
147 | p += 4; |
148 | len -= 4; |
149 | break; |
150 | case X25_FAC_CLASS_D: |
151 | if (len < p[1] + 2) |
152 | return -1; |
153 | switch (*p) { |
154 | case X25_FAC_CALLING_AE: |
155 | if (p[1] > X25_MAX_DTE_FACIL_LEN || p[1] <= 1) |
156 | return -1; |
157 | dte_facs->calling_len = p[2]; |
158 | memcpy(dte_facs->calling_ae, &p[3], p[1] - 1); |
159 | *vc_fac_mask |= X25_MASK_CALLING_AE; |
160 | break; |
161 | case X25_FAC_CALLED_AE: |
162 | if (p[1] > X25_MAX_DTE_FACIL_LEN || p[1] <= 1) |
163 | return -1; |
164 | dte_facs->called_len = p[2]; |
165 | memcpy(dte_facs->called_ae, &p[3], p[1] - 1); |
166 | *vc_fac_mask |= X25_MASK_CALLED_AE; |
167 | break; |
168 | default: |
169 | printk(KERN_DEBUG "X.25: unknown facility %02X," |
170 | "length %d\n", p[0], p[1]); |
171 | break; |
172 | } |
173 | len -= p[1] + 2; |
174 | p += p[1] + 2; |
175 | break; |
176 | } |
177 | } |
178 | |
179 | return p - skb->data; |
180 | } |
181 | |
182 | /* |
183 | * Create a set of facilities. |
184 | */ |
185 | int x25_create_facilities(unsigned char *buffer, |
186 | struct x25_facilities *facilities, |
187 | struct x25_dte_facilities *dte_facs, unsigned long facil_mask) |
188 | { |
189 | unsigned char *p = buffer + 1; |
190 | int len; |
191 | |
192 | if (!facil_mask) { |
193 | /* |
194 | * Length of the facilities field in call_req or |
195 | * call_accept packets |
196 | */ |
197 | buffer[0] = 0; |
198 | len = 1; /* 1 byte for the length field */ |
199 | return len; |
200 | } |
201 | |
202 | if (facilities->reverse && (facil_mask & X25_MASK_REVERSE)) { |
203 | *p++ = X25_FAC_REVERSE; |
204 | *p++ = facilities->reverse; |
205 | } |
206 | |
207 | if (facilities->throughput && (facil_mask & X25_MASK_THROUGHPUT)) { |
208 | *p++ = X25_FAC_THROUGHPUT; |
209 | *p++ = facilities->throughput; |
210 | } |
211 | |
212 | if ((facilities->pacsize_in || facilities->pacsize_out) && |
213 | (facil_mask & X25_MASK_PACKET_SIZE)) { |
214 | *p++ = X25_FAC_PACKET_SIZE; |
215 | *p++ = facilities->pacsize_in ? : facilities->pacsize_out; |
216 | *p++ = facilities->pacsize_out ? : facilities->pacsize_in; |
217 | } |
218 | |
219 | if ((facilities->winsize_in || facilities->winsize_out) && |
220 | (facil_mask & X25_MASK_WINDOW_SIZE)) { |
221 | *p++ = X25_FAC_WINDOW_SIZE; |
222 | *p++ = facilities->winsize_in ? : facilities->winsize_out; |
223 | *p++ = facilities->winsize_out ? : facilities->winsize_in; |
224 | } |
225 | |
226 | if (facil_mask & (X25_MASK_CALLING_AE|X25_MASK_CALLED_AE)) { |
227 | *p++ = X25_MARKER; |
228 | *p++ = X25_DTE_SERVICES; |
229 | } |
230 | |
231 | if (dte_facs->calling_len && (facil_mask & X25_MASK_CALLING_AE)) { |
232 | unsigned bytecount = (dte_facs->calling_len + 1) >> 1; |
233 | *p++ = X25_FAC_CALLING_AE; |
234 | *p++ = 1 + bytecount; |
235 | *p++ = dte_facs->calling_len; |
236 | memcpy(p, dte_facs->calling_ae, bytecount); |
237 | p += bytecount; |
238 | } |
239 | |
240 | if (dte_facs->called_len && (facil_mask & X25_MASK_CALLED_AE)) { |
241 | unsigned bytecount = (dte_facs->called_len % 2) ? |
242 | dte_facs->called_len / 2 + 1 : |
243 | dte_facs->called_len / 2; |
244 | *p++ = X25_FAC_CALLED_AE; |
245 | *p++ = 1 + bytecount; |
246 | *p++ = dte_facs->called_len; |
247 | memcpy(p, dte_facs->called_ae, bytecount); |
248 | p+=bytecount; |
249 | } |
250 | |
251 | len = p - buffer; |
252 | buffer[0] = len - 1; |
253 | |
254 | return len; |
255 | } |
256 | |
257 | /* |
258 | * Try to reach a compromise on a set of facilities. |
259 | * |
260 | * The only real problem is with reverse charging. |
261 | */ |
262 | int x25_negotiate_facilities(struct sk_buff *skb, struct sock *sk, |
263 | struct x25_facilities *new, struct x25_dte_facilities *dte) |
264 | { |
265 | struct x25_sock *x25 = x25_sk(sk); |
266 | struct x25_facilities *ours = &x25->facilities; |
267 | struct x25_facilities theirs; |
268 | int len; |
269 | |
270 | memset(&theirs, 0, sizeof(theirs)); |
271 | memcpy(new, ours, sizeof(*new)); |
272 | |
273 | len = x25_parse_facilities(skb, &theirs, dte, &x25->vc_facil_mask); |
274 | if (len < 0) |
275 | return len; |
276 | |
277 | /* |
278 | * They want reverse charging, we won't accept it. |
279 | */ |
280 | if ((theirs.reverse & 0x01 ) && (ours->reverse & 0x01)) { |
281 | SOCK_DEBUG(sk, "X.25: rejecting reverse charging request\n"); |
282 | return -1; |
283 | } |
284 | |
285 | new->reverse = theirs.reverse; |
286 | |
287 | if (theirs.throughput) { |
288 | int theirs_in = theirs.throughput & 0x0f; |
289 | int theirs_out = theirs.throughput & 0xf0; |
290 | int ours_in = ours->throughput & 0x0f; |
291 | int ours_out = ours->throughput & 0xf0; |
292 | if (!ours_in || theirs_in < ours_in) { |
293 | SOCK_DEBUG(sk, "X.25: inbound throughput negotiated\n"); |
294 | new->throughput = (new->throughput & 0xf0) | theirs_in; |
295 | } |
296 | if (!ours_out || theirs_out < ours_out) { |
297 | SOCK_DEBUG(sk, |
298 | "X.25: outbound throughput negotiated\n"); |
299 | new->throughput = (new->throughput & 0x0f) | theirs_out; |
300 | } |
301 | } |
302 | |
303 | if (theirs.pacsize_in && theirs.pacsize_out) { |
304 | if (theirs.pacsize_in < ours->pacsize_in) { |
305 | SOCK_DEBUG(sk, "X.25: packet size inwards negotiated down\n"); |
306 | new->pacsize_in = theirs.pacsize_in; |
307 | } |
308 | if (theirs.pacsize_out < ours->pacsize_out) { |
309 | SOCK_DEBUG(sk, "X.25: packet size outwards negotiated down\n"); |
310 | new->pacsize_out = theirs.pacsize_out; |
311 | } |
312 | } |
313 | |
314 | if (theirs.winsize_in && theirs.winsize_out) { |
315 | if (theirs.winsize_in < ours->winsize_in) { |
316 | SOCK_DEBUG(sk, "X.25: window size inwards negotiated down\n"); |
317 | new->winsize_in = theirs.winsize_in; |
318 | } |
319 | if (theirs.winsize_out < ours->winsize_out) { |
320 | SOCK_DEBUG(sk, "X.25: window size outwards negotiated down\n"); |
321 | new->winsize_out = theirs.winsize_out; |
322 | } |
323 | } |
324 | |
325 | return len; |
326 | } |
327 | |
328 | /* |
329 | * Limit values of certain facilities according to the capability of the |
330 | * currently attached x25 link. |
331 | */ |
332 | void x25_limit_facilities(struct x25_facilities *facilities, |
333 | struct x25_neigh *nb) |
334 | { |
335 | |
336 | if (!nb->extended) { |
337 | if (facilities->winsize_in > 7) { |
338 | printk(KERN_DEBUG "X.25: incoming winsize limited to 7\n"); |
339 | facilities->winsize_in = 7; |
340 | } |
341 | if (facilities->winsize_out > 7) { |
342 | facilities->winsize_out = 7; |
343 | printk( KERN_DEBUG "X.25: outgoing winsize limited to 7\n"); |
344 | } |
345 | } |
346 | } |
347 |
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