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 * Parse a set of facilities into the facilities structures. Unrecognised 32 * facilities are written to the debug log file. 33 */ 34 int x25_parse_facilities(struct sk_buff *skb, struct x25_facilities *facilities, 35 struct x25_dte_facilities *dte_facs, unsigned long *vc_fac_mask) 36 { 37 unsigned char *p = skb->data; 38 unsigned int len; 39 40 *vc_fac_mask = 0; 41 42 /* 43 * The kernel knows which facilities were set on an incoming call but 44 * currently this information is not available to userspace. Here we 45 * give userspace who read incoming call facilities 0 length to indicate 46 * it wasn't set. 47 */ 48 dte_facs->calling_len = 0; 49 dte_facs->called_len = 0; 50 memset(dte_facs->called_ae, '\0', sizeof(dte_facs->called_ae)); 51 memset(dte_facs->calling_ae, '\0', sizeof(dte_facs->calling_ae)); 52 53 if (skb->len < 1) 54 return 0; 55 56 len = *p++; 57 58 if (len >= skb->len) 59 return -1; 60 61 while (len > 0) { 62 switch (*p & X25_FAC_CLASS_MASK) { 63 case X25_FAC_CLASS_A: 64 switch (*p) { 65 case X25_FAC_REVERSE: 66 if((p[1] & 0x81) == 0x81) { 67 facilities->reverse = p[1] & 0x81; 68 *vc_fac_mask |= X25_MASK_REVERSE; 69 break; 70 } 71 72 if((p[1] & 0x01) == 0x01) { 73 facilities->reverse = p[1] & 0x01; 74 *vc_fac_mask |= X25_MASK_REVERSE; 75 break; 76 } 77 78 if((p[1] & 0x80) == 0x80) { 79 facilities->reverse = p[1] & 0x80; 80 *vc_fac_mask |= X25_MASK_REVERSE; 81 break; 82 } 83 84 if(p[1] == 0x00) { 85 facilities->reverse 86 = X25_DEFAULT_REVERSE; 87 *vc_fac_mask |= X25_MASK_REVERSE; 88 break; 89 } 90 91 case X25_FAC_THROUGHPUT: 92 facilities->throughput = p[1]; 93 *vc_fac_mask |= X25_MASK_THROUGHPUT; 94 break; 95 case X25_MARKER: 96 break; 97 default: 98 printk(KERN_DEBUG "X.25: unknown facility " 99 "%02X, value %02X\n", 100 p[0], p[1]); 101 break; 102 } 103 p += 2; 104 len -= 2; 105 break; 106 case X25_FAC_CLASS_B: 107 switch (*p) { 108 case X25_FAC_PACKET_SIZE: 109 facilities->pacsize_in = p[1]; 110 facilities->pacsize_out = p[2]; 111 *vc_fac_mask |= X25_MASK_PACKET_SIZE; 112 break; 113 case X25_FAC_WINDOW_SIZE: 114 facilities->winsize_in = p[1]; 115 facilities->winsize_out = p[2]; 116 *vc_fac_mask |= X25_MASK_WINDOW_SIZE; 117 break; 118 default: 119 printk(KERN_DEBUG "X.25: unknown facility " 120 "%02X, values %02X, %02X\n", 121 p[0], p[1], p[2]); 122 break; 123 } 124 p += 3; 125 len -= 3; 126 break; 127 case X25_FAC_CLASS_C: 128 printk(KERN_DEBUG "X.25: unknown facility %02X, " 129 "values %02X, %02X, %02X\n", 130 p[0], p[1], p[2], p[3]); 131 p += 4; 132 len -= 4; 133 break; 134 case X25_FAC_CLASS_D: 135 switch (*p) { 136 case X25_FAC_CALLING_AE: 137 if (p[1] > X25_MAX_DTE_FACIL_LEN) 138 break; 139 dte_facs->calling_len = p[2]; 140 memcpy(dte_facs->calling_ae, &p[3], p[1] - 1); 141 *vc_fac_mask |= X25_MASK_CALLING_AE; 142 break; 143 case X25_FAC_CALLED_AE: 144 if (p[1] > X25_MAX_DTE_FACIL_LEN) 145 break; 146 dte_facs->called_len = p[2]; 147 memcpy(dte_facs->called_ae, &p[3], p[1] - 1); 148 *vc_fac_mask |= X25_MASK_CALLED_AE; 149 break; 150 default: 151 printk(KERN_DEBUG "X.25: unknown facility %02X," 152 "length %d, values %02X, %02X, " 153 "%02X, %02X\n", 154 p[0], p[1], p[2], p[3], p[4], p[5]); 155 break; 156 } 157 len -= p[1] + 2; 158 p += p[1] + 2; 159 break; 160 } 161 } 162 163 return p - skb->data; 164 } 165 166 /* 167 * Create a set of facilities. 168 */ 169 int x25_create_facilities(unsigned char *buffer, 170 struct x25_facilities *facilities, 171 struct x25_dte_facilities *dte_facs, unsigned long facil_mask) 172 { 173 unsigned char *p = buffer + 1; 174 int len; 175 176 if (!facil_mask) { 177 /* 178 * Length of the facilities field in call_req or 179 * call_accept packets 180 */ 181 buffer[0] = 0; 182 len = 1; /* 1 byte for the length field */ 183 return len; 184 } 185 186 if (facilities->reverse && (facil_mask & X25_MASK_REVERSE)) { 187 *p++ = X25_FAC_REVERSE; 188 *p++ = facilities->reverse; 189 } 190 191 if (facilities->throughput && (facil_mask & X25_MASK_THROUGHPUT)) { 192 *p++ = X25_FAC_THROUGHPUT; 193 *p++ = facilities->throughput; 194 } 195 196 if ((facilities->pacsize_in || facilities->pacsize_out) && 197 (facil_mask & X25_MASK_PACKET_SIZE)) { 198 *p++ = X25_FAC_PACKET_SIZE; 199 *p++ = facilities->pacsize_in ? : facilities->pacsize_out; 200 *p++ = facilities->pacsize_out ? : facilities->pacsize_in; 201 } 202 203 if ((facilities->winsize_in || facilities->winsize_out) && 204 (facil_mask & X25_MASK_WINDOW_SIZE)) { 205 *p++ = X25_FAC_WINDOW_SIZE; 206 *p++ = facilities->winsize_in ? : facilities->winsize_out; 207 *p++ = facilities->winsize_out ? : facilities->winsize_in; 208 } 209 210 if (facil_mask & (X25_MASK_CALLING_AE|X25_MASK_CALLED_AE)) { 211 *p++ = X25_MARKER; 212 *p++ = X25_DTE_SERVICES; 213 } 214 215 if (dte_facs->calling_len && (facil_mask & X25_MASK_CALLING_AE)) { 216 unsigned bytecount = (dte_facs->calling_len + 1) >> 1; 217 *p++ = X25_FAC_CALLING_AE; 218 *p++ = 1 + bytecount; 219 *p++ = dte_facs->calling_len; 220 memcpy(p, dte_facs->calling_ae, bytecount); 221 p += bytecount; 222 } 223 224 if (dte_facs->called_len && (facil_mask & X25_MASK_CALLED_AE)) { 225 unsigned bytecount = (dte_facs->called_len % 2) ? 226 dte_facs->called_len / 2 + 1 : 227 dte_facs->called_len / 2; 228 *p++ = X25_FAC_CALLED_AE; 229 *p++ = 1 + bytecount; 230 *p++ = dte_facs->called_len; 231 memcpy(p, dte_facs->called_ae, bytecount); 232 p+=bytecount; 233 } 234 235 len = p - buffer; 236 buffer[0] = len - 1; 237 238 return len; 239 } 240 241 /* 242 * Try to reach a compromise on a set of facilities. 243 * 244 * The only real problem is with reverse charging. 245 */ 246 int x25_negotiate_facilities(struct sk_buff *skb, struct sock *sk, 247 struct x25_facilities *new, struct x25_dte_facilities *dte) 248 { 249 struct x25_sock *x25 = x25_sk(sk); 250 struct x25_facilities *ours = &x25->facilities; 251 struct x25_facilities theirs; 252 int len; 253 254 memset(&theirs, 0, sizeof(theirs)); 255 memcpy(new, ours, sizeof(*new)); 256 257 len = x25_parse_facilities(skb, &theirs, dte, &x25->vc_facil_mask); 258 if (len < 0) 259 return len; 260 261 /* 262 * They want reverse charging, we won't accept it. 263 */ 264 if ((theirs.reverse & 0x01 ) && (ours->reverse & 0x01)) { 265 SOCK_DEBUG(sk, "X.25: rejecting reverse charging request\n"); 266 return -1; 267 } 268 269 new->reverse = theirs.reverse; 270 271 if (theirs.throughput) { 272 int theirs_in = theirs.throughput & 0x0f; 273 int theirs_out = theirs.throughput & 0xf0; 274 int ours_in = ours->throughput & 0x0f; 275 int ours_out = ours->throughput & 0xf0; 276 if (!ours_in || theirs_in < ours_in) { 277 SOCK_DEBUG(sk, "X.25: inbound throughput negotiated\n"); 278 new->throughput = (new->throughput & 0xf0) | theirs_in; 279 } 280 if (!ours_out || theirs_out < ours_out) { 281 SOCK_DEBUG(sk, 282 "X.25: outbound throughput negotiated\n"); 283 new->throughput = (new->throughput & 0x0f) | theirs_out; 284 } 285 } 286 287 if (theirs.pacsize_in && theirs.pacsize_out) { 288 if (theirs.pacsize_in < ours->pacsize_in) { 289 SOCK_DEBUG(sk, "X.25: packet size inwards negotiated down\n"); 290 new->pacsize_in = theirs.pacsize_in; 291 } 292 if (theirs.pacsize_out < ours->pacsize_out) { 293 SOCK_DEBUG(sk, "X.25: packet size outwards negotiated down\n"); 294 new->pacsize_out = theirs.pacsize_out; 295 } 296 } 297 298 if (theirs.winsize_in && theirs.winsize_out) { 299 if (theirs.winsize_in < ours->winsize_in) { 300 SOCK_DEBUG(sk, "X.25: window size inwards negotiated down\n"); 301 new->winsize_in = theirs.winsize_in; 302 } 303 if (theirs.winsize_out < ours->winsize_out) { 304 SOCK_DEBUG(sk, "X.25: window size outwards negotiated down\n"); 305 new->winsize_out = theirs.winsize_out; 306 } 307 } 308 309 return len; 310 } 311 312 /* 313 * Limit values of certain facilities according to the capability of the 314 * currently attached x25 link. 315 */ 316 void x25_limit_facilities(struct x25_facilities *facilities, 317 struct x25_neigh *nb) 318 { 319 320 if (!nb->extended) { 321 if (facilities->winsize_in > 7) { 322 printk(KERN_DEBUG "X.25: incoming winsize limited to 7\n"); 323 facilities->winsize_in = 7; 324 } 325 if (facilities->winsize_out > 7) { 326 facilities->winsize_out = 7; 327 printk( KERN_DEBUG "X.25: outgoing winsize limited to 7\n"); 328 } 329 } 330 } 331