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 code. 19 * New timer architecture. 20 * 2000-03-20 Daniela Squassoni Disabling/enabling of facilities 21 * negotiation. 22 * 2000-11-10 Henner Eisen Check and reset for out-of-sequence 23 * i-frames. 24 */ 25 26 #include <linux/slab.h> 27 #include <linux/errno.h> 28 #include <linux/kernel.h> 29 #include <linux/string.h> 30 #include <linux/skbuff.h> 31 #include <net/sock.h> 32 #include <net/tcp_states.h> 33 #include <net/x25.h> 34 35 static int x25_queue_rx_frame(struct sock *sk, struct sk_buff *skb, int more) 36 { 37 struct sk_buff *skbo, *skbn = skb; 38 struct x25_sock *x25 = x25_sk(sk); 39 40 if (more) { 41 x25->fraglen += skb->len; 42 skb_queue_tail(&x25->fragment_queue, skb); 43 skb_set_owner_r(skb, sk); 44 return 0; 45 } 46 47 if (!more && x25->fraglen > 0) { /* End of fragment */ 48 int len = x25->fraglen + skb->len; 49 50 if ((skbn = alloc_skb(len, GFP_ATOMIC)) == NULL){ 51 kfree_skb(skb); 52 return 1; 53 } 54 55 skb_queue_tail(&x25->fragment_queue, skb); 56 57 skb_reset_transport_header(skbn); 58 59 skbo = skb_dequeue(&x25->fragment_queue); 60 skb_copy_from_linear_data(skbo, skb_put(skbn, skbo->len), 61 skbo->len); 62 kfree_skb(skbo); 63 64 while ((skbo = 65 skb_dequeue(&x25->fragment_queue)) != NULL) { 66 skb_pull(skbo, (x25->neighbour->extended) ? 67 X25_EXT_MIN_LEN : X25_STD_MIN_LEN); 68 skb_copy_from_linear_data(skbo, 69 skb_put(skbn, skbo->len), 70 skbo->len); 71 kfree_skb(skbo); 72 } 73 74 x25->fraglen = 0; 75 } 76 77 skb_set_owner_r(skbn, sk); 78 skb_queue_tail(&sk->sk_receive_queue, skbn); 79 if (!sock_flag(sk, SOCK_DEAD)) 80 sk->sk_data_ready(sk, skbn->len); 81 82 return 0; 83 } 84 85 /* 86 * State machine for state 1, Awaiting Call Accepted State. 87 * The handling of the timer(s) is in file x25_timer.c. 88 * Handling of state 0 and connection release is in af_x25.c. 89 */ 90 static int x25_state1_machine(struct sock *sk, struct sk_buff *skb, int frametype) 91 { 92 struct x25_address source_addr, dest_addr; 93 int len; 94 struct x25_sock *x25 = x25_sk(sk); 95 96 switch (frametype) { 97 case X25_CALL_ACCEPTED: { 98 99 x25_stop_timer(sk); 100 x25->condition = 0x00; 101 x25->vs = 0; 102 x25->va = 0; 103 x25->vr = 0; 104 x25->vl = 0; 105 x25->state = X25_STATE_3; 106 sk->sk_state = TCP_ESTABLISHED; 107 /* 108 * Parse the data in the frame. 109 */ 110 if (!pskb_may_pull(skb, X25_STD_MIN_LEN)) 111 goto out_clear; 112 skb_pull(skb, X25_STD_MIN_LEN); 113 114 len = x25_parse_address_block(skb, &source_addr, 115 &dest_addr); 116 if (len > 0) 117 skb_pull(skb, len); 118 else if (len < 0) 119 goto out_clear; 120 121 len = x25_parse_facilities(skb, &x25->facilities, 122 &x25->dte_facilities, 123 &x25->vc_facil_mask); 124 if (len > 0) 125 skb_pull(skb, len); 126 else if (len < 0) 127 goto out_clear; 128 /* 129 * Copy any Call User Data. 130 */ 131 if (skb->len > 0) { 132 if (skb->len > X25_MAX_CUD_LEN) 133 goto out_clear; 134 135 skb_copy_bits(skb, 0, x25->calluserdata.cuddata, 136 skb->len); 137 x25->calluserdata.cudlength = skb->len; 138 } 139 if (!sock_flag(sk, SOCK_DEAD)) 140 sk->sk_state_change(sk); 141 break; 142 } 143 case X25_CLEAR_REQUEST: 144 if (!pskb_may_pull(skb, X25_STD_MIN_LEN + 2)) 145 goto out_clear; 146 147 x25_write_internal(sk, X25_CLEAR_CONFIRMATION); 148 x25_disconnect(sk, ECONNREFUSED, skb->data[3], skb->data[4]); 149 break; 150 151 default: 152 break; 153 } 154 155 return 0; 156 157 out_clear: 158 x25_write_internal(sk, X25_CLEAR_REQUEST); 159 x25->state = X25_STATE_2; 160 x25_start_t23timer(sk); 161 return 0; 162 } 163 164 /* 165 * State machine for state 2, Awaiting Clear Confirmation State. 166 * The handling of the timer(s) is in file x25_timer.c 167 * Handling of state 0 and connection release is in af_x25.c. 168 */ 169 static int x25_state2_machine(struct sock *sk, struct sk_buff *skb, int frametype) 170 { 171 switch (frametype) { 172 173 case X25_CLEAR_REQUEST: 174 if (!pskb_may_pull(skb, X25_STD_MIN_LEN + 2)) 175 goto out_clear; 176 177 x25_write_internal(sk, X25_CLEAR_CONFIRMATION); 178 x25_disconnect(sk, 0, skb->data[3], skb->data[4]); 179 break; 180 181 case X25_CLEAR_CONFIRMATION: 182 x25_disconnect(sk, 0, 0, 0); 183 break; 184 185 default: 186 break; 187 } 188 189 return 0; 190 191 out_clear: 192 x25_write_internal(sk, X25_CLEAR_REQUEST); 193 x25_start_t23timer(sk); 194 return 0; 195 } 196 197 /* 198 * State machine for state 3, Connected State. 199 * The handling of the timer(s) is in file x25_timer.c 200 * Handling of state 0 and connection release is in af_x25.c. 201 */ 202 static int x25_state3_machine(struct sock *sk, struct sk_buff *skb, int frametype, int ns, int nr, int q, int d, int m) 203 { 204 int queued = 0; 205 int modulus; 206 struct x25_sock *x25 = x25_sk(sk); 207 208 modulus = (x25->neighbour->extended) ? X25_EMODULUS : X25_SMODULUS; 209 210 switch (frametype) { 211 212 case X25_RESET_REQUEST: 213 x25_write_internal(sk, X25_RESET_CONFIRMATION); 214 x25_stop_timer(sk); 215 x25->condition = 0x00; 216 x25->vs = 0; 217 x25->vr = 0; 218 x25->va = 0; 219 x25->vl = 0; 220 x25_requeue_frames(sk); 221 break; 222 223 case X25_CLEAR_REQUEST: 224 if (!pskb_may_pull(skb, X25_STD_MIN_LEN + 2)) 225 goto out_clear; 226 227 x25_write_internal(sk, X25_CLEAR_CONFIRMATION); 228 x25_disconnect(sk, 0, skb->data[3], skb->data[4]); 229 break; 230 231 case X25_RR: 232 case X25_RNR: 233 if (!x25_validate_nr(sk, nr)) { 234 x25_clear_queues(sk); 235 x25_write_internal(sk, X25_RESET_REQUEST); 236 x25_start_t22timer(sk); 237 x25->condition = 0x00; 238 x25->vs = 0; 239 x25->vr = 0; 240 x25->va = 0; 241 x25->vl = 0; 242 x25->state = X25_STATE_4; 243 } else { 244 x25_frames_acked(sk, nr); 245 if (frametype == X25_RNR) { 246 x25->condition |= X25_COND_PEER_RX_BUSY; 247 } else { 248 x25->condition &= ~X25_COND_PEER_RX_BUSY; 249 } 250 } 251 break; 252 253 case X25_DATA: /* XXX */ 254 x25->condition &= ~X25_COND_PEER_RX_BUSY; 255 if ((ns != x25->vr) || !x25_validate_nr(sk, nr)) { 256 x25_clear_queues(sk); 257 x25_write_internal(sk, X25_RESET_REQUEST); 258 x25_start_t22timer(sk); 259 x25->condition = 0x00; 260 x25->vs = 0; 261 x25->vr = 0; 262 x25->va = 0; 263 x25->vl = 0; 264 x25->state = X25_STATE_4; 265 break; 266 } 267 x25_frames_acked(sk, nr); 268 if (ns == x25->vr) { 269 if (x25_queue_rx_frame(sk, skb, m) == 0) { 270 x25->vr = (x25->vr + 1) % modulus; 271 queued = 1; 272 } else { 273 /* Should never happen */ 274 x25_clear_queues(sk); 275 x25_write_internal(sk, X25_RESET_REQUEST); 276 x25_start_t22timer(sk); 277 x25->condition = 0x00; 278 x25->vs = 0; 279 x25->vr = 0; 280 x25->va = 0; 281 x25->vl = 0; 282 x25->state = X25_STATE_4; 283 break; 284 } 285 if (atomic_read(&sk->sk_rmem_alloc) > 286 (sk->sk_rcvbuf >> 1)) 287 x25->condition |= X25_COND_OWN_RX_BUSY; 288 } 289 /* 290 * If the window is full Ack it immediately, else 291 * start the holdback timer. 292 */ 293 if (((x25->vl + x25->facilities.winsize_in) % modulus) == x25->vr) { 294 x25->condition &= ~X25_COND_ACK_PENDING; 295 x25_stop_timer(sk); 296 x25_enquiry_response(sk); 297 } else { 298 x25->condition |= X25_COND_ACK_PENDING; 299 x25_start_t2timer(sk); 300 } 301 break; 302 303 case X25_INTERRUPT_CONFIRMATION: 304 clear_bit(X25_INTERRUPT_FLAG, &x25->flags); 305 break; 306 307 case X25_INTERRUPT: 308 if (sock_flag(sk, SOCK_URGINLINE)) 309 queued = !sock_queue_rcv_skb(sk, skb); 310 else { 311 skb_set_owner_r(skb, sk); 312 skb_queue_tail(&x25->interrupt_in_queue, skb); 313 queued = 1; 314 } 315 sk_send_sigurg(sk); 316 x25_write_internal(sk, X25_INTERRUPT_CONFIRMATION); 317 break; 318 319 default: 320 printk(KERN_WARNING "x25: unknown %02X in state 3\n", frametype); 321 break; 322 } 323 324 return queued; 325 326 out_clear: 327 x25_write_internal(sk, X25_CLEAR_REQUEST); 328 x25->state = X25_STATE_2; 329 x25_start_t23timer(sk); 330 return 0; 331 } 332 333 /* 334 * State machine for state 4, Awaiting Reset Confirmation State. 335 * The handling of the timer(s) is in file x25_timer.c 336 * Handling of state 0 and connection release is in af_x25.c. 337 */ 338 static int x25_state4_machine(struct sock *sk, struct sk_buff *skb, int frametype) 339 { 340 struct x25_sock *x25 = x25_sk(sk); 341 342 switch (frametype) { 343 344 case X25_RESET_REQUEST: 345 x25_write_internal(sk, X25_RESET_CONFIRMATION); 346 case X25_RESET_CONFIRMATION: { 347 x25_stop_timer(sk); 348 x25->condition = 0x00; 349 x25->va = 0; 350 x25->vr = 0; 351 x25->vs = 0; 352 x25->vl = 0; 353 x25->state = X25_STATE_3; 354 x25_requeue_frames(sk); 355 break; 356 } 357 case X25_CLEAR_REQUEST: 358 if (!pskb_may_pull(skb, X25_STD_MIN_LEN + 2)) 359 goto out_clear; 360 361 x25_write_internal(sk, X25_CLEAR_CONFIRMATION); 362 x25_disconnect(sk, 0, skb->data[3], skb->data[4]); 363 break; 364 365 default: 366 break; 367 } 368 369 return 0; 370 371 out_clear: 372 x25_write_internal(sk, X25_CLEAR_REQUEST); 373 x25->state = X25_STATE_2; 374 x25_start_t23timer(sk); 375 return 0; 376 } 377 378 /* Higher level upcall for a LAPB frame */ 379 int x25_process_rx_frame(struct sock *sk, struct sk_buff *skb) 380 { 381 struct x25_sock *x25 = x25_sk(sk); 382 int queued = 0, frametype, ns, nr, q, d, m; 383 384 if (x25->state == X25_STATE_0) 385 return 0; 386 387 frametype = x25_decode(sk, skb, &ns, &nr, &q, &d, &m); 388 389 switch (x25->state) { 390 case X25_STATE_1: 391 queued = x25_state1_machine(sk, skb, frametype); 392 break; 393 case X25_STATE_2: 394 queued = x25_state2_machine(sk, skb, frametype); 395 break; 396 case X25_STATE_3: 397 queued = x25_state3_machine(sk, skb, frametype, ns, nr, q, d, m); 398 break; 399 case X25_STATE_4: 400 queued = x25_state4_machine(sk, skb, frametype); 401 break; 402 } 403 404 x25_kick(sk); 405 406 return queued; 407 } 408 409 int x25_backlog_rcv(struct sock *sk, struct sk_buff *skb) 410 { 411 int queued = x25_process_rx_frame(sk, skb); 412 413 if (!queued) 414 kfree_skb(skb); 415 416 return 0; 417 } 418