File: /usr/src/linux/net/x25/x25_facilities.c
1 /*
2 * X.25 Packet Layer release 002
3 *
4 * This is ALPHA test software. This code may break your machine, randomly fail to work with new
5 * releases, misbehave and/or generally screw up. It might even work.
6 *
7 * This code REQUIRES 2.1.15 or higher
8 *
9 * This module:
10 * This module is free software; you can redistribute it and/or
11 * modify it under the terms of the GNU General Public License
12 * as published by the Free Software Foundation; either version
13 * 2 of the License, or (at your option) any later version.
14 *
15 * History
16 * X.25 001 Split from x25_subr.c
17 * mar/20/00 Daniela Squassoni Disabling/enabling of facilities
18 * negotiation.
19 */
20
21 #include <linux/errno.h>
22 #include <linux/types.h>
23 #include <linux/socket.h>
24 #include <linux/in.h>
25 #include <linux/kernel.h>
26 #include <linux/sched.h>
27 #include <linux/timer.h>
28 #include <linux/string.h>
29 #include <linux/sockios.h>
30 #include <linux/net.h>
31 #include <linux/inet.h>
32 #include <linux/netdevice.h>
33 #include <linux/skbuff.h>
34 #include <net/sock.h>
35 #include <asm/segment.h>
36 #include <asm/system.h>
37 #include <linux/fcntl.h>
38 #include <linux/mm.h>
39 #include <linux/interrupt.h>
40 #include <net/x25.h>
41
42 /*
43 * Parse a set of facilities into the facilities structure. Unrecognised
44 * facilities are written to the debug log file.
45 */
46 int x25_parse_facilities(struct sk_buff *skb, struct x25_facilities *facilities, unsigned long *vc_fac_mask)
47 {
48 unsigned int len;
49 unsigned char *p = skb->data;
50
51 len = *p++;
52 *vc_fac_mask = 0;
53
54 while (len > 0) {
55 switch (*p & X25_FAC_CLASS_MASK) {
56 case X25_FAC_CLASS_A:
57 switch (*p) {
58 case X25_FAC_REVERSE:
59 facilities->reverse = (p[1] & 0x01);
60 *vc_fac_mask |= X25_MASK_REVERSE;
61 break;
62 case X25_FAC_THROUGHPUT:
63 facilities->throughput = p[1];
64 *vc_fac_mask |= X25_MASK_THROUGHPUT;
65 break;
66 default:
67 printk(KERN_DEBUG "X.25: unknown facility %02X, value %02X\n", p[0], p[1]);
68 break;
69 }
70 p += 2;
71 len -= 2;
72 break;
73
74 case X25_FAC_CLASS_B:
75 switch (*p) {
76 case X25_FAC_PACKET_SIZE:
77 facilities->pacsize_in = p[1];
78 facilities->pacsize_out = p[2];
79 *vc_fac_mask |= X25_MASK_PACKET_SIZE;
80 break;
81 case X25_FAC_WINDOW_SIZE:
82 facilities->winsize_in = p[1];
83 facilities->winsize_out = p[2];
84 *vc_fac_mask |= X25_MASK_WINDOW_SIZE;
85 break;
86 default:
87 printk(KERN_DEBUG "X.25: unknown facility %02X, values %02X, %02X\n", p[0], p[1], p[2]);
88 break;
89 }
90 p += 3;
91 len -= 3;
92 break;
93
94 case X25_FAC_CLASS_C:
95 printk(KERN_DEBUG "X.25: unknown facility %02X, values %02X, %02X, %02X\n", p[0], p[1], p[2], p[3]);
96 p += 4;
97 len -= 4;
98 break;
99
100 case X25_FAC_CLASS_D:
101 printk(KERN_DEBUG "X.25: unknown facility %02X, length %d, values %02X, %02X, %02X, %02X\n", p[0], p[1], p[2], p[3], p[4], p[5]);
102 p += p[1] + 2;
103 len -= p[1] + 2;
104 break;
105 }
106 }
107
108 return p - skb->data;
109 }
110
111 /*
112 * Create a set of facilities.
113 */
114 int x25_create_facilities(unsigned char *buffer, struct x25_facilities *facilities, unsigned long facil_mask)
115 {
116 unsigned char *p = buffer + 1;
117 int len;
118
119 if (facil_mask == 0) {
120 buffer [0] = 0; /* length of the facilities field in call_req or call_accept packets */
121 len = 1; /* 1 byte for the length field */
122 return len;
123 }
124
125 if ((facilities->reverse != 0) && (facil_mask & X25_MASK_REVERSE)) {
126 *p++ = X25_FAC_REVERSE;
127 *p++ = (facilities->reverse) ? 0x01 : 0x00;
128 }
129
130 if ((facilities->throughput != 0) && (facil_mask & X25_MASK_THROUGHPUT)) {
131 *p++ = X25_FAC_THROUGHPUT;
132 *p++ = facilities->throughput;
133 }
134
135 if ((facilities->pacsize_in != 0 || facilities->pacsize_out != 0) && (facil_mask & X25_MASK_PACKET_SIZE)) {
136 *p++ = X25_FAC_PACKET_SIZE;
137 *p++ = (facilities->pacsize_in == 0) ? facilities->pacsize_out : facilities->pacsize_in;
138 *p++ = (facilities->pacsize_out == 0) ? facilities->pacsize_in : facilities->pacsize_out;
139 }
140
141 if ((facilities->winsize_in != 0 || facilities->winsize_out != 0) && (facil_mask & X25_MASK_WINDOW_SIZE)) {
142 *p++ = X25_FAC_WINDOW_SIZE;
143 *p++ = (facilities->winsize_in == 0) ? facilities->winsize_out : facilities->winsize_in;
144 *p++ = (facilities->winsize_out == 0) ? facilities->winsize_in : facilities->winsize_out;
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, struct x25_facilities *new)
159 {
160 struct x25_facilities *ours;
161 struct x25_facilities theirs;
162 int len;
163
164 memset(&theirs, 0x00, sizeof(struct x25_facilities));
165
166 ours = &sk->protinfo.x25->facilities;
167
168 *new = *ours;
169
170 len = x25_parse_facilities(skb, &theirs, &sk->protinfo.x25->vc_facil_mask);
171
172 /*
173 * They want reverse charging, we won't accept it.
174 */
175 if (theirs.reverse != 0 && ours->reverse == 0) {
176 SOCK_DEBUG(sk, "X.25: rejecting reverse charging request");
177 return -1;
178 }
179
180 new->reverse = theirs.reverse;
181
182 if (theirs.throughput != 0) {
183 if (theirs.throughput < ours->throughput) {
184 SOCK_DEBUG(sk, "X.25: throughput negotiated down");
185 new->throughput = theirs.throughput;
186 }
187 }
188
189 if (theirs.pacsize_in != 0 && theirs.pacsize_out != 0) {
190 if (theirs.pacsize_in < ours->pacsize_in) {
191 SOCK_DEBUG(sk, "X.25: packet size inwards negotiated down");
192 new->pacsize_in = theirs.pacsize_in;
193 }
194 if (theirs.pacsize_out < ours->pacsize_out) {
195 SOCK_DEBUG(sk, "X.25: packet size outwards negotiated down");
196 new->pacsize_out = theirs.pacsize_out;
197 }
198 }
199
200 if (theirs.winsize_in != 0 && theirs.winsize_out != 0) {
201 if (theirs.winsize_in < ours->winsize_in) {
202 SOCK_DEBUG(sk, "X.25: window size inwards negotiated down");
203 new->winsize_in = theirs.winsize_in;
204 }
205 if (theirs.winsize_out < ours->winsize_out) {
206 SOCK_DEBUG(sk, "X.25: window size outwards negotiated down");
207 new->winsize_out = theirs.winsize_out;
208 }
209 }
210
211 return len;
212 }
213
214 /*
215 * Limit values of certain facilities according to the capability of the
216 * currently attached x25 link.
217 */
218 void x25_limit_facilities(struct x25_facilities *facilities,
219 struct x25_neigh *neighbour)
220 {
221
222 if( ! neighbour->extended ){
223 if( facilities->winsize_in > 7 ){
224 printk(KERN_DEBUG "X.25: incoming winsize limited to 7\n");
225 facilities->winsize_in = 7;
226 }
227 if( facilities->winsize_out > 7 ){
228 facilities->winsize_out = 7;
229 printk( KERN_DEBUG "X.25: outgoing winsize limited to 7\n");
230 }
231 }
232 }
233