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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 | #define pr_fmt(fmt) "X25: " fmt |
25 | |
26 | #include <linux/kernel.h> |
27 | #include <linux/string.h> |
28 | #include <linux/skbuff.h> |
29 | #include <net/sock.h> |
30 | #include <net/x25.h> |
31 | |
32 | /** |
33 | * x25_parse_facilities - Parse facilities from skb into the facilities structs |
34 | * |
35 | * @skb: sk_buff to parse |
36 | * @facilities: Regular facilities, updated as facilities are found |
37 | * @dte_facs: ITU DTE facilities, updated as DTE facilities are found |
38 | * @vc_fac_mask: mask is updated with all facilities found |
39 | * |
40 | * Return codes: |
41 | * -1 - Parsing error, caller should drop call and clean up |
42 | * 0 - Parse OK, this skb has no facilities |
43 | * >0 - Parse OK, returns the length of the facilities header |
44 | * |
45 | */ |
46 | int x25_parse_facilities(struct sk_buff *skb, struct x25_facilities *facilities, |
47 | struct x25_dte_facilities *dte_facs, unsigned long *vc_fac_mask) |
48 | { |
49 | unsigned char *p; |
50 | unsigned int len; |
51 | |
52 | *vc_fac_mask = 0; |
53 | |
54 | /* |
55 | * The kernel knows which facilities were set on an incoming call but |
56 | * currently this information is not available to userspace. Here we |
57 | * give userspace who read incoming call facilities 0 length to indicate |
58 | * it wasn't set. |
59 | */ |
60 | dte_facs->calling_len = 0; |
61 | dte_facs->called_len = 0; |
62 | memset(dte_facs->called_ae, '\0', sizeof(dte_facs->called_ae)); |
63 | memset(dte_facs->calling_ae, '\0', sizeof(dte_facs->calling_ae)); |
64 | |
65 | if (!pskb_may_pull(skb, 1)) |
66 | return 0; |
67 | |
68 | len = skb->data[0]; |
69 | |
70 | if (!pskb_may_pull(skb, 1 + len)) |
71 | return -1; |
72 | |
73 | p = skb->data + 1; |
74 | |
75 | while (len > 0) { |
76 | switch (*p & X25_FAC_CLASS_MASK) { |
77 | case X25_FAC_CLASS_A: |
78 | if (len < 2) |
79 | return -1; |
80 | switch (*p) { |
81 | case X25_FAC_REVERSE: |
82 | if((p[1] & 0x81) == 0x81) { |
83 | facilities->reverse = p[1] & 0x81; |
84 | *vc_fac_mask |= X25_MASK_REVERSE; |
85 | break; |
86 | } |
87 | |
88 | if((p[1] & 0x01) == 0x01) { |
89 | facilities->reverse = p[1] & 0x01; |
90 | *vc_fac_mask |= X25_MASK_REVERSE; |
91 | break; |
92 | } |
93 | |
94 | if((p[1] & 0x80) == 0x80) { |
95 | facilities->reverse = p[1] & 0x80; |
96 | *vc_fac_mask |= X25_MASK_REVERSE; |
97 | break; |
98 | } |
99 | |
100 | if(p[1] == 0x00) { |
101 | facilities->reverse |
102 | = X25_DEFAULT_REVERSE; |
103 | *vc_fac_mask |= X25_MASK_REVERSE; |
104 | break; |
105 | } |
106 | |
107 | case X25_FAC_THROUGHPUT: |
108 | facilities->throughput = p[1]; |
109 | *vc_fac_mask |= X25_MASK_THROUGHPUT; |
110 | break; |
111 | case X25_MARKER: |
112 | break; |
113 | default: |
114 | pr_debug("unknown facility " |
115 | "%02X, value %02X\n", |
116 | p[0], p[1]); |
117 | break; |
118 | } |
119 | p += 2; |
120 | len -= 2; |
121 | break; |
122 | case X25_FAC_CLASS_B: |
123 | if (len < 3) |
124 | return -1; |
125 | switch (*p) { |
126 | case X25_FAC_PACKET_SIZE: |
127 | facilities->pacsize_in = p[1]; |
128 | facilities->pacsize_out = p[2]; |
129 | *vc_fac_mask |= X25_MASK_PACKET_SIZE; |
130 | break; |
131 | case X25_FAC_WINDOW_SIZE: |
132 | facilities->winsize_in = p[1]; |
133 | facilities->winsize_out = p[2]; |
134 | *vc_fac_mask |= X25_MASK_WINDOW_SIZE; |
135 | break; |
136 | default: |
137 | pr_debug("unknown facility " |
138 | "%02X, values %02X, %02X\n", |
139 | p[0], p[1], p[2]); |
140 | break; |
141 | } |
142 | p += 3; |
143 | len -= 3; |
144 | break; |
145 | case X25_FAC_CLASS_C: |
146 | if (len < 4) |
147 | return -1; |
148 | pr_debug("unknown facility %02X, " |
149 | "values %02X, %02X, %02X\n", |
150 | p[0], p[1], p[2], p[3]); |
151 | p += 4; |
152 | len -= 4; |
153 | break; |
154 | case X25_FAC_CLASS_D: |
155 | if (len < p[1] + 2) |
156 | return -1; |
157 | switch (*p) { |
158 | case X25_FAC_CALLING_AE: |
159 | if (p[1] > X25_MAX_DTE_FACIL_LEN || p[1] <= 1) |
160 | return -1; |
161 | if (p[2] > X25_MAX_AE_LEN) |
162 | return -1; |
163 | dte_facs->calling_len = p[2]; |
164 | memcpy(dte_facs->calling_ae, &p[3], p[1] - 1); |
165 | *vc_fac_mask |= X25_MASK_CALLING_AE; |
166 | break; |
167 | case X25_FAC_CALLED_AE: |
168 | if (p[1] > X25_MAX_DTE_FACIL_LEN || p[1] <= 1) |
169 | return -1; |
170 | if (p[2] > X25_MAX_AE_LEN) |
171 | return -1; |
172 | dte_facs->called_len = p[2]; |
173 | memcpy(dte_facs->called_ae, &p[3], p[1] - 1); |
174 | *vc_fac_mask |= X25_MASK_CALLED_AE; |
175 | break; |
176 | default: |
177 | pr_debug("unknown facility %02X," |
178 | "length %d\n", p[0], p[1]); |
179 | break; |
180 | } |
181 | len -= p[1] + 2; |
182 | p += p[1] + 2; |
183 | break; |
184 | } |
185 | } |
186 | |
187 | return p - skb->data; |
188 | } |
189 | |
190 | /* |
191 | * Create a set of facilities. |
192 | */ |
193 | int x25_create_facilities(unsigned char *buffer, |
194 | struct x25_facilities *facilities, |
195 | struct x25_dte_facilities *dte_facs, unsigned long facil_mask) |
196 | { |
197 | unsigned char *p = buffer + 1; |
198 | int len; |
199 | |
200 | if (!facil_mask) { |
201 | /* |
202 | * Length of the facilities field in call_req or |
203 | * call_accept packets |
204 | */ |
205 | buffer[0] = 0; |
206 | len = 1; /* 1 byte for the length field */ |
207 | return len; |
208 | } |
209 | |
210 | if (facilities->reverse && (facil_mask & X25_MASK_REVERSE)) { |
211 | *p++ = X25_FAC_REVERSE; |
212 | *p++ = facilities->reverse; |
213 | } |
214 | |
215 | if (facilities->throughput && (facil_mask & X25_MASK_THROUGHPUT)) { |
216 | *p++ = X25_FAC_THROUGHPUT; |
217 | *p++ = facilities->throughput; |
218 | } |
219 | |
220 | if ((facilities->pacsize_in || facilities->pacsize_out) && |
221 | (facil_mask & X25_MASK_PACKET_SIZE)) { |
222 | *p++ = X25_FAC_PACKET_SIZE; |
223 | *p++ = facilities->pacsize_in ? : facilities->pacsize_out; |
224 | *p++ = facilities->pacsize_out ? : facilities->pacsize_in; |
225 | } |
226 | |
227 | if ((facilities->winsize_in || facilities->winsize_out) && |
228 | (facil_mask & X25_MASK_WINDOW_SIZE)) { |
229 | *p++ = X25_FAC_WINDOW_SIZE; |
230 | *p++ = facilities->winsize_in ? : facilities->winsize_out; |
231 | *p++ = facilities->winsize_out ? : facilities->winsize_in; |
232 | } |
233 | |
234 | if (facil_mask & (X25_MASK_CALLING_AE|X25_MASK_CALLED_AE)) { |
235 | *p++ = X25_MARKER; |
236 | *p++ = X25_DTE_SERVICES; |
237 | } |
238 | |
239 | if (dte_facs->calling_len && (facil_mask & X25_MASK_CALLING_AE)) { |
240 | unsigned int bytecount = (dte_facs->calling_len + 1) >> 1; |
241 | *p++ = X25_FAC_CALLING_AE; |
242 | *p++ = 1 + bytecount; |
243 | *p++ = dte_facs->calling_len; |
244 | memcpy(p, dte_facs->calling_ae, bytecount); |
245 | p += bytecount; |
246 | } |
247 | |
248 | if (dte_facs->called_len && (facil_mask & X25_MASK_CALLED_AE)) { |
249 | unsigned int bytecount = (dte_facs->called_len % 2) ? |
250 | dte_facs->called_len / 2 + 1 : |
251 | dte_facs->called_len / 2; |
252 | *p++ = X25_FAC_CALLED_AE; |
253 | *p++ = 1 + bytecount; |
254 | *p++ = dte_facs->called_len; |
255 | memcpy(p, dte_facs->called_ae, bytecount); |
256 | p+=bytecount; |
257 | } |
258 | |
259 | len = p - buffer; |
260 | buffer[0] = len - 1; |
261 | |
262 | return len; |
263 | } |
264 | |
265 | /* |
266 | * Try to reach a compromise on a set of facilities. |
267 | * |
268 | * The only real problem is with reverse charging. |
269 | */ |
270 | int x25_negotiate_facilities(struct sk_buff *skb, struct sock *sk, |
271 | struct x25_facilities *new, struct x25_dte_facilities *dte) |
272 | { |
273 | struct x25_sock *x25 = x25_sk(sk); |
274 | struct x25_facilities *ours = &x25->facilities; |
275 | struct x25_facilities theirs; |
276 | int len; |
277 | |
278 | memset(&theirs, 0, sizeof(theirs)); |
279 | memcpy(new, ours, sizeof(*new)); |
280 | |
281 | len = x25_parse_facilities(skb, &theirs, dte, &x25->vc_facil_mask); |
282 | if (len < 0) |
283 | return len; |
284 | |
285 | /* |
286 | * They want reverse charging, we won't accept it. |
287 | */ |
288 | if ((theirs.reverse & 0x01 ) && (ours->reverse & 0x01)) { |
289 | SOCK_DEBUG(sk, "X.25: rejecting reverse charging request\n"); |
290 | return -1; |
291 | } |
292 | |
293 | new->reverse = theirs.reverse; |
294 | |
295 | if (theirs.throughput) { |
296 | int theirs_in = theirs.throughput & 0x0f; |
297 | int theirs_out = theirs.throughput & 0xf0; |
298 | int ours_in = ours->throughput & 0x0f; |
299 | int ours_out = ours->throughput & 0xf0; |
300 | if (!ours_in || theirs_in < ours_in) { |
301 | SOCK_DEBUG(sk, "X.25: inbound throughput negotiated\n"); |
302 | new->throughput = (new->throughput & 0xf0) | theirs_in; |
303 | } |
304 | if (!ours_out || theirs_out < ours_out) { |
305 | SOCK_DEBUG(sk, |
306 | "X.25: outbound throughput negotiated\n"); |
307 | new->throughput = (new->throughput & 0x0f) | theirs_out; |
308 | } |
309 | } |
310 | |
311 | if (theirs.pacsize_in && theirs.pacsize_out) { |
312 | if (theirs.pacsize_in < ours->pacsize_in) { |
313 | SOCK_DEBUG(sk, "X.25: packet size inwards negotiated down\n"); |
314 | new->pacsize_in = theirs.pacsize_in; |
315 | } |
316 | if (theirs.pacsize_out < ours->pacsize_out) { |
317 | SOCK_DEBUG(sk, "X.25: packet size outwards negotiated down\n"); |
318 | new->pacsize_out = theirs.pacsize_out; |
319 | } |
320 | } |
321 | |
322 | if (theirs.winsize_in && theirs.winsize_out) { |
323 | if (theirs.winsize_in < ours->winsize_in) { |
324 | SOCK_DEBUG(sk, "X.25: window size inwards negotiated down\n"); |
325 | new->winsize_in = theirs.winsize_in; |
326 | } |
327 | if (theirs.winsize_out < ours->winsize_out) { |
328 | SOCK_DEBUG(sk, "X.25: window size outwards negotiated down\n"); |
329 | new->winsize_out = theirs.winsize_out; |
330 | } |
331 | } |
332 | |
333 | return len; |
334 | } |
335 | |
336 | /* |
337 | * Limit values of certain facilities according to the capability of the |
338 | * currently attached x25 link. |
339 | */ |
340 | void x25_limit_facilities(struct x25_facilities *facilities, |
341 | struct x25_neigh *nb) |
342 | { |
343 | |
344 | if (!nb->extended) { |
345 | if (facilities->winsize_in > 7) { |
346 | pr_debug("incoming winsize limited to 7\n"); |
347 | facilities->winsize_in = 7; |
348 | } |
349 | if (facilities->winsize_out > 7) { |
350 | facilities->winsize_out = 7; |
351 | pr_debug("outgoing winsize limited to 7\n"); |
352 | } |
353 | } |
354 | } |
355 |
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Tags:
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