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 Jonathan Naylor Started coding. 18 * X.25 002 Jonathan Naylor Centralised disconnection processing. 19 * mar/20/00 Daniela Squassoni Disabling/enabling of facilities 20 * negotiation. 21 * jun/24/01 Arnaldo C. Melo use skb_queue_purge, cleanups 22 * apr/04/15 Shaun Pereira Fast select with no 23 * restriction on response. 24 */ 25 26 #include <linux/slab.h> 27 #include <linux/kernel.h> 28 #include <linux/string.h> 29 #include <linux/skbuff.h> 30 #include <net/sock.h> 31 #include <net/tcp_states.h> 32 #include <net/x25.h> 33 34 /* 35 * This routine purges all of the queues of frames. 36 */ 37 void x25_clear_queues(struct sock *sk) 38 { 39 struct x25_sock *x25 = x25_sk(sk); 40 41 skb_queue_purge(&sk->sk_write_queue); 42 skb_queue_purge(&x25->ack_queue); 43 skb_queue_purge(&x25->interrupt_in_queue); 44 skb_queue_purge(&x25->interrupt_out_queue); 45 skb_queue_purge(&x25->fragment_queue); 46 } 47 48 49 /* 50 * This routine purges the input queue of those frames that have been 51 * acknowledged. This replaces the boxes labelled "V(a) <- N(r)" on the 52 * SDL diagram. 53 */ 54 void x25_frames_acked(struct sock *sk, unsigned short nr) 55 { 56 struct sk_buff *skb; 57 struct x25_sock *x25 = x25_sk(sk); 58 int modulus = x25->neighbour->extended ? X25_EMODULUS : X25_SMODULUS; 59 60 /* 61 * Remove all the ack-ed frames from the ack queue. 62 */ 63 if (x25->va != nr) 64 while (skb_peek(&x25->ack_queue) && x25->va != nr) { 65 skb = skb_dequeue(&x25->ack_queue); 66 kfree_skb(skb); 67 x25->va = (x25->va + 1) % modulus; 68 } 69 } 70 71 void x25_requeue_frames(struct sock *sk) 72 { 73 struct sk_buff *skb, *skb_prev = NULL; 74 75 /* 76 * Requeue all the un-ack-ed frames on the output queue to be picked 77 * up by x25_kick. This arrangement handles the possibility of an empty 78 * output queue. 79 */ 80 while ((skb = skb_dequeue(&x25_sk(sk)->ack_queue)) != NULL) { 81 if (!skb_prev) 82 skb_queue_head(&sk->sk_write_queue, skb); 83 else 84 skb_append(skb_prev, skb, &sk->sk_write_queue); 85 skb_prev = skb; 86 } 87 } 88 89 /* 90 * Validate that the value of nr is between va and vs. Return true or 91 * false for testing. 92 */ 93 int x25_validate_nr(struct sock *sk, unsigned short nr) 94 { 95 struct x25_sock *x25 = x25_sk(sk); 96 unsigned short vc = x25->va; 97 int modulus = x25->neighbour->extended ? X25_EMODULUS : X25_SMODULUS; 98 99 while (vc != x25->vs) { 100 if (nr == vc) 101 return 1; 102 vc = (vc + 1) % modulus; 103 } 104 105 return nr == x25->vs ? 1 : 0; 106 } 107 108 /* 109 * This routine is called when the packet layer internally generates a 110 * control frame. 111 */ 112 void x25_write_internal(struct sock *sk, int frametype) 113 { 114 struct x25_sock *x25 = x25_sk(sk); 115 struct sk_buff *skb; 116 unsigned char *dptr; 117 unsigned char facilities[X25_MAX_FAC_LEN]; 118 unsigned char addresses[1 + X25_ADDR_LEN]; 119 unsigned char lci1, lci2; 120 /* 121 * Default safe frame size. 122 */ 123 int len = X25_MAX_L2_LEN + X25_EXT_MIN_LEN; 124 125 /* 126 * Adjust frame size. 127 */ 128 switch (frametype) { 129 case X25_CALL_REQUEST: 130 len += 1 + X25_ADDR_LEN + X25_MAX_FAC_LEN + X25_MAX_CUD_LEN; 131 break; 132 case X25_CALL_ACCEPTED: /* fast sel with no restr on resp */ 133 if (x25->facilities.reverse & 0x80) { 134 len += 1 + X25_MAX_FAC_LEN + X25_MAX_CUD_LEN; 135 } else { 136 len += 1 + X25_MAX_FAC_LEN; 137 } 138 break; 139 case X25_CLEAR_REQUEST: 140 case X25_RESET_REQUEST: 141 len += 2; 142 break; 143 case X25_RR: 144 case X25_RNR: 145 case X25_REJ: 146 case X25_CLEAR_CONFIRMATION: 147 case X25_INTERRUPT_CONFIRMATION: 148 case X25_RESET_CONFIRMATION: 149 break; 150 default: 151 printk(KERN_ERR "X.25: invalid frame type %02X\n", frametype); 152 return; 153 } 154 155 if ((skb = alloc_skb(len, GFP_ATOMIC)) == NULL) 156 return; 157 158 /* 159 * Space for Ethernet and 802.2 LLC headers. 160 */ 161 skb_reserve(skb, X25_MAX_L2_LEN); 162 163 /* 164 * Make space for the GFI and LCI, and fill them in. 165 */ 166 dptr = skb_put(skb, 2); 167 168 lci1 = (x25->lci >> 8) & 0x0F; 169 lci2 = (x25->lci >> 0) & 0xFF; 170 171 if (x25->neighbour->extended) { 172 *dptr++ = lci1 | X25_GFI_EXTSEQ; 173 *dptr++ = lci2; 174 } else { 175 *dptr++ = lci1 | X25_GFI_STDSEQ; 176 *dptr++ = lci2; 177 } 178 179 /* 180 * Now fill in the frame type specific information. 181 */ 182 switch (frametype) { 183 184 case X25_CALL_REQUEST: 185 dptr = skb_put(skb, 1); 186 *dptr++ = X25_CALL_REQUEST; 187 len = x25_addr_aton(addresses, &x25->dest_addr, 188 &x25->source_addr); 189 dptr = skb_put(skb, len); 190 memcpy(dptr, addresses, len); 191 len = x25_create_facilities(facilities, 192 &x25->facilities, 193 &x25->dte_facilities, 194 x25->neighbour->global_facil_mask); 195 dptr = skb_put(skb, len); 196 memcpy(dptr, facilities, len); 197 dptr = skb_put(skb, x25->calluserdata.cudlength); 198 memcpy(dptr, x25->calluserdata.cuddata, 199 x25->calluserdata.cudlength); 200 x25->calluserdata.cudlength = 0; 201 break; 202 203 case X25_CALL_ACCEPTED: 204 dptr = skb_put(skb, 2); 205 *dptr++ = X25_CALL_ACCEPTED; 206 *dptr++ = 0x00; /* Address lengths */ 207 len = x25_create_facilities(facilities, 208 &x25->facilities, 209 &x25->dte_facilities, 210 x25->vc_facil_mask); 211 dptr = skb_put(skb, len); 212 memcpy(dptr, facilities, len); 213 214 /* fast select with no restriction on response 215 allows call user data. Userland must 216 ensure it is ours and not theirs */ 217 if(x25->facilities.reverse & 0x80) { 218 dptr = skb_put(skb, 219 x25->calluserdata.cudlength); 220 memcpy(dptr, x25->calluserdata.cuddata, 221 x25->calluserdata.cudlength); 222 } 223 x25->calluserdata.cudlength = 0; 224 break; 225 226 case X25_CLEAR_REQUEST: 227 dptr = skb_put(skb, 3); 228 *dptr++ = frametype; 229 *dptr++ = x25->causediag.cause; 230 *dptr++ = x25->causediag.diagnostic; 231 break; 232 233 case X25_RESET_REQUEST: 234 dptr = skb_put(skb, 3); 235 *dptr++ = frametype; 236 *dptr++ = 0x00; /* XXX */ 237 *dptr++ = 0x00; /* XXX */ 238 break; 239 240 case X25_RR: 241 case X25_RNR: 242 case X25_REJ: 243 if (x25->neighbour->extended) { 244 dptr = skb_put(skb, 2); 245 *dptr++ = frametype; 246 *dptr++ = (x25->vr << 1) & 0xFE; 247 } else { 248 dptr = skb_put(skb, 1); 249 *dptr = frametype; 250 *dptr++ |= (x25->vr << 5) & 0xE0; 251 } 252 break; 253 254 case X25_CLEAR_CONFIRMATION: 255 case X25_INTERRUPT_CONFIRMATION: 256 case X25_RESET_CONFIRMATION: 257 dptr = skb_put(skb, 1); 258 *dptr = frametype; 259 break; 260 } 261 262 x25_transmit_link(skb, x25->neighbour); 263 } 264 265 /* 266 * Unpick the contents of the passed X.25 Packet Layer frame. 267 */ 268 int x25_decode(struct sock *sk, struct sk_buff *skb, int *ns, int *nr, int *q, 269 int *d, int *m) 270 { 271 struct x25_sock *x25 = x25_sk(sk); 272 unsigned char *frame; 273 274 if (!pskb_may_pull(skb, X25_STD_MIN_LEN)) 275 return X25_ILLEGAL; 276 frame = skb->data; 277 278 *ns = *nr = *q = *d = *m = 0; 279 280 switch (frame[2]) { 281 case X25_CALL_REQUEST: 282 case X25_CALL_ACCEPTED: 283 case X25_CLEAR_REQUEST: 284 case X25_CLEAR_CONFIRMATION: 285 case X25_INTERRUPT: 286 case X25_INTERRUPT_CONFIRMATION: 287 case X25_RESET_REQUEST: 288 case X25_RESET_CONFIRMATION: 289 case X25_RESTART_REQUEST: 290 case X25_RESTART_CONFIRMATION: 291 case X25_REGISTRATION_REQUEST: 292 case X25_REGISTRATION_CONFIRMATION: 293 case X25_DIAGNOSTIC: 294 return frame[2]; 295 } 296 297 if (x25->neighbour->extended) { 298 if (frame[2] == X25_RR || 299 frame[2] == X25_RNR || 300 frame[2] == X25_REJ) { 301 if (!pskb_may_pull(skb, X25_EXT_MIN_LEN)) 302 return X25_ILLEGAL; 303 frame = skb->data; 304 305 *nr = (frame[3] >> 1) & 0x7F; 306 return frame[2]; 307 } 308 } else { 309 if ((frame[2] & 0x1F) == X25_RR || 310 (frame[2] & 0x1F) == X25_RNR || 311 (frame[2] & 0x1F) == X25_REJ) { 312 *nr = (frame[2] >> 5) & 0x07; 313 return frame[2] & 0x1F; 314 } 315 } 316 317 if (x25->neighbour->extended) { 318 if ((frame[2] & 0x01) == X25_DATA) { 319 if (!pskb_may_pull(skb, X25_EXT_MIN_LEN)) 320 return X25_ILLEGAL; 321 frame = skb->data; 322 323 *q = (frame[0] & X25_Q_BIT) == X25_Q_BIT; 324 *d = (frame[0] & X25_D_BIT) == X25_D_BIT; 325 *m = (frame[3] & X25_EXT_M_BIT) == X25_EXT_M_BIT; 326 *nr = (frame[3] >> 1) & 0x7F; 327 *ns = (frame[2] >> 1) & 0x7F; 328 return X25_DATA; 329 } 330 } else { 331 if ((frame[2] & 0x01) == X25_DATA) { 332 *q = (frame[0] & X25_Q_BIT) == X25_Q_BIT; 333 *d = (frame[0] & X25_D_BIT) == X25_D_BIT; 334 *m = (frame[2] & X25_STD_M_BIT) == X25_STD_M_BIT; 335 *nr = (frame[2] >> 5) & 0x07; 336 *ns = (frame[2] >> 1) & 0x07; 337 return X25_DATA; 338 } 339 } 340 341 printk(KERN_DEBUG "X.25: invalid PLP frame %02X %02X %02X\n", 342 frame[0], frame[1], frame[2]); 343 344 return X25_ILLEGAL; 345 } 346 347 void x25_disconnect(struct sock *sk, int reason, unsigned char cause, 348 unsigned char diagnostic) 349 { 350 struct x25_sock *x25 = x25_sk(sk); 351 352 x25_clear_queues(sk); 353 x25_stop_timer(sk); 354 355 x25->lci = 0; 356 x25->state = X25_STATE_0; 357 358 x25->causediag.cause = cause; 359 x25->causediag.diagnostic = diagnostic; 360 361 sk->sk_state = TCP_CLOSE; 362 sk->sk_err = reason; 363 sk->sk_shutdown |= SEND_SHUTDOWN; 364 365 if (!sock_flag(sk, SOCK_DEAD)) { 366 sk->sk_state_change(sk); 367 sock_set_flag(sk, SOCK_DEAD); 368 } 369 } 370 371 /* 372 * Clear an own-rx-busy condition and tell the peer about this, provided 373 * that there is a significant amount of free receive buffer space available. 374 */ 375 void x25_check_rbuf(struct sock *sk) 376 { 377 struct x25_sock *x25 = x25_sk(sk); 378 379 if (atomic_read(&sk->sk_rmem_alloc) < (sk->sk_rcvbuf >> 1) && 380 (x25->condition & X25_COND_OWN_RX_BUSY)) { 381 x25->condition &= ~X25_COND_OWN_RX_BUSY; 382 x25->condition &= ~X25_COND_ACK_PENDING; 383 x25->vl = x25->vr; 384 x25_write_internal(sk, X25_RR); 385 x25_stop_timer(sk); 386 } 387 } 388 389