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