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1da177e4 LT |
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 | */ | |
21 | ||
22 | #include <linux/kernel.h> | |
23 | #include <linux/string.h> | |
24 | #include <linux/skbuff.h> | |
25 | #include <net/sock.h> | |
26 | #include <net/x25.h> | |
27 | ||
28 | /* | |
29 | * Parse a set of facilities into the facilities structure. Unrecognised | |
30 | * facilities are written to the debug log file. | |
31 | */ | |
32 | int x25_parse_facilities(struct sk_buff *skb, | |
33 | struct x25_facilities *facilities, | |
34 | unsigned long *vc_fac_mask) | |
35 | { | |
36 | unsigned char *p = skb->data; | |
37 | unsigned int len = *p++; | |
38 | ||
39 | *vc_fac_mask = 0; | |
40 | ||
41 | while (len > 0) { | |
42 | switch (*p & X25_FAC_CLASS_MASK) { | |
43 | case X25_FAC_CLASS_A: | |
44 | switch (*p) { | |
45 | case X25_FAC_REVERSE: | |
46 | facilities->reverse = p[1] & 0x01; | |
47 | *vc_fac_mask |= X25_MASK_REVERSE; | |
48 | break; | |
49 | case X25_FAC_THROUGHPUT: | |
50 | facilities->throughput = p[1]; | |
51 | *vc_fac_mask |= X25_MASK_THROUGHPUT; | |
52 | break; | |
53 | default: | |
54 | printk(KERN_DEBUG "X.25: unknown facility " | |
55 | "%02X, value %02X\n", | |
56 | p[0], p[1]); | |
57 | break; | |
58 | } | |
59 | p += 2; | |
60 | len -= 2; | |
61 | break; | |
62 | case X25_FAC_CLASS_B: | |
63 | switch (*p) { | |
64 | case X25_FAC_PACKET_SIZE: | |
65 | facilities->pacsize_in = p[1]; | |
66 | facilities->pacsize_out = p[2]; | |
67 | *vc_fac_mask |= X25_MASK_PACKET_SIZE; | |
68 | break; | |
69 | case X25_FAC_WINDOW_SIZE: | |
70 | facilities->winsize_in = p[1]; | |
71 | facilities->winsize_out = p[2]; | |
72 | *vc_fac_mask |= X25_MASK_WINDOW_SIZE; | |
73 | break; | |
74 | default: | |
75 | printk(KERN_DEBUG "X.25: unknown facility " | |
76 | "%02X, values %02X, %02X\n", | |
77 | p[0], p[1], p[2]); | |
78 | break; | |
79 | } | |
80 | p += 3; | |
81 | len -= 3; | |
82 | break; | |
83 | case X25_FAC_CLASS_C: | |
84 | printk(KERN_DEBUG "X.25: unknown facility %02X, " | |
85 | "values %02X, %02X, %02X\n", | |
86 | p[0], p[1], p[2], p[3]); | |
87 | p += 4; | |
88 | len -= 4; | |
89 | break; | |
90 | case X25_FAC_CLASS_D: | |
91 | printk(KERN_DEBUG "X.25: unknown facility %02X, " | |
92 | "length %d, values %02X, %02X, %02X, %02X\n", | |
93 | p[0], p[1], p[2], p[3], p[4], p[5]); | |
94 | len -= p[1] + 2; | |
95 | p += p[1] + 2; | |
96 | break; | |
97 | } | |
98 | } | |
99 | ||
100 | return p - skb->data; | |
101 | } | |
102 | ||
103 | /* | |
104 | * Create a set of facilities. | |
105 | */ | |
106 | int x25_create_facilities(unsigned char *buffer, | |
107 | struct x25_facilities *facilities, | |
108 | unsigned long facil_mask) | |
109 | { | |
110 | unsigned char *p = buffer + 1; | |
111 | int len; | |
112 | ||
113 | if (!facil_mask) { | |
114 | /* | |
115 | * Length of the facilities field in call_req or | |
116 | * call_accept packets | |
117 | */ | |
118 | buffer[0] = 0; | |
119 | len = 1; /* 1 byte for the length field */ | |
120 | return len; | |
121 | } | |
122 | ||
123 | if (facilities->reverse && (facil_mask & X25_MASK_REVERSE)) { | |
124 | *p++ = X25_FAC_REVERSE; | |
125 | *p++ = !!facilities->reverse; | |
126 | } | |
127 | ||
128 | if (facilities->throughput && (facil_mask & X25_MASK_THROUGHPUT)) { | |
129 | *p++ = X25_FAC_THROUGHPUT; | |
130 | *p++ = facilities->throughput; | |
131 | } | |
132 | ||
133 | if ((facilities->pacsize_in || facilities->pacsize_out) && | |
134 | (facil_mask & X25_MASK_PACKET_SIZE)) { | |
135 | *p++ = X25_FAC_PACKET_SIZE; | |
136 | *p++ = facilities->pacsize_in ? : facilities->pacsize_out; | |
137 | *p++ = facilities->pacsize_out ? : facilities->pacsize_in; | |
138 | } | |
139 | ||
140 | if ((facilities->winsize_in || facilities->winsize_out) && | |
141 | (facil_mask & X25_MASK_WINDOW_SIZE)) { | |
142 | *p++ = X25_FAC_WINDOW_SIZE; | |
143 | *p++ = facilities->winsize_in ? : facilities->winsize_out; | |
144 | *p++ = facilities->winsize_out ? : facilities->winsize_in; | |
145 | } | |
146 | ||
147 | len = p - buffer; | |
148 | buffer[0] = len - 1; | |
149 | ||
150 | return len; | |
151 | } | |
152 | ||
153 | /* | |
154 | * Try to reach a compromise on a set of facilities. | |
155 | * | |
156 | * The only real problem is with reverse charging. | |
157 | */ | |
158 | int x25_negotiate_facilities(struct sk_buff *skb, struct sock *sk, | |
159 | struct x25_facilities *new) | |
160 | { | |
161 | struct x25_sock *x25 = x25_sk(sk); | |
162 | struct x25_facilities *ours = &x25->facilities; | |
163 | struct x25_facilities theirs; | |
164 | int len; | |
165 | ||
166 | memset(&theirs, 0, sizeof(theirs)); | |
167 | memcpy(new, ours, sizeof(*new)); | |
168 | ||
169 | len = x25_parse_facilities(skb, &theirs, &x25->vc_facil_mask); | |
170 | ||
171 | /* | |
172 | * They want reverse charging, we won't accept it. | |
173 | */ | |
174 | if (theirs.reverse && ours->reverse) { | |
175 | SOCK_DEBUG(sk, "X.25: rejecting reverse charging request"); | |
176 | return -1; | |
177 | } | |
178 | ||
179 | new->reverse = theirs.reverse; | |
180 | ||
181 | if (theirs.throughput) { | |
182 | if (theirs.throughput < ours->throughput) { | |
183 | SOCK_DEBUG(sk, "X.25: throughput negotiated down"); | |
184 | new->throughput = theirs.throughput; | |
185 | } | |
186 | } | |
187 | ||
188 | if (theirs.pacsize_in && theirs.pacsize_out) { | |
189 | if (theirs.pacsize_in < ours->pacsize_in) { | |
190 | SOCK_DEBUG(sk, "X.25: packet size inwards negotiated down"); | |
191 | new->pacsize_in = theirs.pacsize_in; | |
192 | } | |
193 | if (theirs.pacsize_out < ours->pacsize_out) { | |
194 | SOCK_DEBUG(sk, "X.25: packet size outwards negotiated down"); | |
195 | new->pacsize_out = theirs.pacsize_out; | |
196 | } | |
197 | } | |
198 | ||
199 | if (theirs.winsize_in && theirs.winsize_out) { | |
200 | if (theirs.winsize_in < ours->winsize_in) { | |
201 | SOCK_DEBUG(sk, "X.25: window size inwards negotiated down"); | |
202 | new->winsize_in = theirs.winsize_in; | |
203 | } | |
204 | if (theirs.winsize_out < ours->winsize_out) { | |
205 | SOCK_DEBUG(sk, "X.25: window size outwards negotiated down"); | |
206 | new->winsize_out = theirs.winsize_out; | |
207 | } | |
208 | } | |
209 | ||
210 | return len; | |
211 | } | |
212 | ||
213 | /* | |
214 | * Limit values of certain facilities according to the capability of the | |
215 | * currently attached x25 link. | |
216 | */ | |
217 | void x25_limit_facilities(struct x25_facilities *facilities, | |
218 | struct x25_neigh *nb) | |
219 | { | |
220 | ||
221 | if (!nb->extended) { | |
222 | if (facilities->winsize_in > 7) { | |
223 | printk(KERN_DEBUG "X.25: incoming winsize limited to 7\n"); | |
224 | facilities->winsize_in = 7; | |
225 | } | |
226 | if (facilities->winsize_out > 7) { | |
227 | facilities->winsize_out = 7; | |
228 | printk( KERN_DEBUG "X.25: outgoing winsize limited to 7\n"); | |
229 | } | |
230 | } | |
231 | } |