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 facilities, 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; 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 (!pskb_may_pull(skb, 1)) 64 return 0; 65 66 len = skb->data[0]; 67 68 if (!pskb_may_pull(skb, 1 + len)) 69 return -1; 70 71 p = skb->data + 1; 72 73 while (len > 0) { 74 switch (*p & X25_FAC_CLASS_MASK) { 75 case X25_FAC_CLASS_A: 76 if (len < 2) 77 return -1; 78 switch (*p) { 79 case X25_FAC_REVERSE: 80 if((p[1] & 0x81) == 0x81) { 81 facilities->reverse = p[1] & 0x81; 82 *vc_fac_mask |= X25_MASK_REVERSE; 83 break; 84 } 85 86 if((p[1] & 0x01) == 0x01) { 87 facilities->reverse = p[1] & 0x01; 88 *vc_fac_mask |= X25_MASK_REVERSE; 89 break; 90 } 91 92 if((p[1] & 0x80) == 0x80) { 93 facilities->reverse = p[1] & 0x80; 94 *vc_fac_mask |= X25_MASK_REVERSE; 95 break; 96 } 97 98 if(p[1] == 0x00) { 99 facilities->reverse 100 = X25_DEFAULT_REVERSE; 101 *vc_fac_mask |= X25_MASK_REVERSE; 102 break; 103 } 104 105 case X25_FAC_THROUGHPUT: 106 facilities->throughput = p[1]; 107 *vc_fac_mask |= X25_MASK_THROUGHPUT; 108 break; 109 case X25_MARKER: 110 break; 111 default: 112 printk(KERN_DEBUG "X.25: unknown facility " 113 "%02X, value %02X\n", 114 p[0], p[1]); 115 break; 116 } 117 p += 2; 118 len -= 2; 119 break; 120 case X25_FAC_CLASS_B: 121 if (len < 3) 122 return -1; 123 switch (*p) { 124 case X25_FAC_PACKET_SIZE: 125 facilities->pacsize_in = p[1]; 126 facilities->pacsize_out = p[2]; 127 *vc_fac_mask |= X25_MASK_PACKET_SIZE; 128 break; 129 case X25_FAC_WINDOW_SIZE: 130 facilities->winsize_in = p[1]; 131 facilities->winsize_out = p[2]; 132 *vc_fac_mask |= X25_MASK_WINDOW_SIZE; 133 break; 134 default: 135 printk(KERN_DEBUG "X.25: unknown facility " 136 "%02X, values %02X, %02X\n", 137 p[0], p[1], p[2]); 138 break; 139 } 140 p += 3; 141 len -= 3; 142 break; 143 case X25_FAC_CLASS_C: 144 if (len < 4) 145 return -1; 146 printk(KERN_DEBUG "X.25: unknown facility %02X, " 147 "values %02X, %02X, %02X\n", 148 p[0], p[1], p[2], p[3]); 149 p += 4; 150 len -= 4; 151 break; 152 case X25_FAC_CLASS_D: 153 if (len < p[1] + 2) 154 return -1; 155 switch (*p) { 156 case X25_FAC_CALLING_AE: 157 if (p[1] > X25_MAX_DTE_FACIL_LEN || p[1] <= 1) 158 return -1; 159 if (p[2] > X25_MAX_AE_LEN) 160 return -1; 161 dte_facs->calling_len = p[2]; 162 memcpy(dte_facs->calling_ae, &p[3], p[1] - 1); 163 *vc_fac_mask |= X25_MASK_CALLING_AE; 164 break; 165 case X25_FAC_CALLED_AE: 166 if (p[1] > X25_MAX_DTE_FACIL_LEN || p[1] <= 1) 167 return -1; 168 if (p[2] > X25_MAX_AE_LEN) 169 return -1; 170 dte_facs->called_len = p[2]; 171 memcpy(dte_facs->called_ae, &p[3], p[1] - 1); 172 *vc_fac_mask |= X25_MASK_CALLED_AE; 173 break; 174 default: 175 printk(KERN_DEBUG "X.25: unknown facility %02X," 176 "length %d\n", p[0], p[1]); 177 break; 178 } 179 len -= p[1] + 2; 180 p += p[1] + 2; 181 break; 182 } 183 } 184 185 return p - skb->data; 186 } 187 188 /* 189 * Create a set of facilities. 190 */ 191 int x25_create_facilities(unsigned char *buffer, 192 struct x25_facilities *facilities, 193 struct x25_dte_facilities *dte_facs, unsigned long facil_mask) 194 { 195 unsigned char *p = buffer + 1; 196 int len; 197 198 if (!facil_mask) { 199 /* 200 * Length of the facilities field in call_req or 201 * call_accept packets 202 */ 203 buffer[0] = 0; 204 len = 1; /* 1 byte for the length field */ 205 return len; 206 } 207 208 if (facilities->reverse && (facil_mask & X25_MASK_REVERSE)) { 209 *p++ = X25_FAC_REVERSE; 210 *p++ = facilities->reverse; 211 } 212 213 if (facilities->throughput && (facil_mask & X25_MASK_THROUGHPUT)) { 214 *p++ = X25_FAC_THROUGHPUT; 215 *p++ = facilities->throughput; 216 } 217 218 if ((facilities->pacsize_in || facilities->pacsize_out) && 219 (facil_mask & X25_MASK_PACKET_SIZE)) { 220 *p++ = X25_FAC_PACKET_SIZE; 221 *p++ = facilities->pacsize_in ? : facilities->pacsize_out; 222 *p++ = facilities->pacsize_out ? : facilities->pacsize_in; 223 } 224 225 if ((facilities->winsize_in || facilities->winsize_out) && 226 (facil_mask & X25_MASK_WINDOW_SIZE)) { 227 *p++ = X25_FAC_WINDOW_SIZE; 228 *p++ = facilities->winsize_in ? : facilities->winsize_out; 229 *p++ = facilities->winsize_out ? : facilities->winsize_in; 230 } 231 232 if (facil_mask & (X25_MASK_CALLING_AE|X25_MASK_CALLED_AE)) { 233 *p++ = X25_MARKER; 234 *p++ = X25_DTE_SERVICES; 235 } 236 237 if (dte_facs->calling_len && (facil_mask & X25_MASK_CALLING_AE)) { 238 unsigned int bytecount = (dte_facs->calling_len + 1) >> 1; 239 *p++ = X25_FAC_CALLING_AE; 240 *p++ = 1 + bytecount; 241 *p++ = dte_facs->calling_len; 242 memcpy(p, dte_facs->calling_ae, bytecount); 243 p += bytecount; 244 } 245 246 if (dte_facs->called_len && (facil_mask & X25_MASK_CALLED_AE)) { 247 unsigned int bytecount = (dte_facs->called_len % 2) ? 248 dte_facs->called_len / 2 + 1 : 249 dte_facs->called_len / 2; 250 *p++ = X25_FAC_CALLED_AE; 251 *p++ = 1 + bytecount; 252 *p++ = dte_facs->called_len; 253 memcpy(p, dte_facs->called_ae, bytecount); 254 p+=bytecount; 255 } 256 257 len = p - buffer; 258 buffer[0] = len - 1; 259 260 return len; 261 } 262 263 /* 264 * Try to reach a compromise on a set of facilities. 265 * 266 * The only real problem is with reverse charging. 267 */ 268 int x25_negotiate_facilities(struct sk_buff *skb, struct sock *sk, 269 struct x25_facilities *new, struct x25_dte_facilities *dte) 270 { 271 struct x25_sock *x25 = x25_sk(sk); 272 struct x25_facilities *ours = &x25->facilities; 273 struct x25_facilities theirs; 274 int len; 275 276 memset(&theirs, 0, sizeof(theirs)); 277 memcpy(new, ours, sizeof(*new)); 278 279 len = x25_parse_facilities(skb, &theirs, dte, &x25->vc_facil_mask); 280 if (len < 0) 281 return len; 282 283 /* 284 * They want reverse charging, we won't accept it. 285 */ 286 if ((theirs.reverse & 0x01 ) && (ours->reverse & 0x01)) { 287 SOCK_DEBUG(sk, "X.25: rejecting reverse charging request\n"); 288 return -1; 289 } 290 291 new->reverse = theirs.reverse; 292 293 if (theirs.throughput) { 294 int theirs_in = theirs.throughput & 0x0f; 295 int theirs_out = theirs.throughput & 0xf0; 296 int ours_in = ours->throughput & 0x0f; 297 int ours_out = ours->throughput & 0xf0; 298 if (!ours_in || theirs_in < ours_in) { 299 SOCK_DEBUG(sk, "X.25: inbound throughput negotiated\n"); 300 new->throughput = (new->throughput & 0xf0) | theirs_in; 301 } 302 if (!ours_out || theirs_out < ours_out) { 303 SOCK_DEBUG(sk, 304 "X.25: outbound throughput negotiated\n"); 305 new->throughput = (new->throughput & 0x0f) | theirs_out; 306 } 307 } 308 309 if (theirs.pacsize_in && theirs.pacsize_out) { 310 if (theirs.pacsize_in < ours->pacsize_in) { 311 SOCK_DEBUG(sk, "X.25: packet size inwards negotiated down\n"); 312 new->pacsize_in = theirs.pacsize_in; 313 } 314 if (theirs.pacsize_out < ours->pacsize_out) { 315 SOCK_DEBUG(sk, "X.25: packet size outwards negotiated down\n"); 316 new->pacsize_out = theirs.pacsize_out; 317 } 318 } 319 320 if (theirs.winsize_in && theirs.winsize_out) { 321 if (theirs.winsize_in < ours->winsize_in) { 322 SOCK_DEBUG(sk, "X.25: window size inwards negotiated down\n"); 323 new->winsize_in = theirs.winsize_in; 324 } 325 if (theirs.winsize_out < ours->winsize_out) { 326 SOCK_DEBUG(sk, "X.25: window size outwards negotiated down\n"); 327 new->winsize_out = theirs.winsize_out; 328 } 329 } 330 331 return len; 332 } 333 334 /* 335 * Limit values of certain facilities according to the capability of the 336 * currently attached x25 link. 337 */ 338 void x25_limit_facilities(struct x25_facilities *facilities, 339 struct x25_neigh *nb) 340 { 341 342 if (!nb->extended) { 343 if (facilities->winsize_in > 7) { 344 printk(KERN_DEBUG "X.25: incoming winsize limited to 7\n"); 345 facilities->winsize_in = 7; 346 } 347 if (facilities->winsize_out > 7) { 348 facilities->winsize_out = 7; 349 printk( KERN_DEBUG "X.25: outgoing winsize limited to 7\n"); 350 } 351 } 352 } 353