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 skb_pull(skb, X25_STD_MIN_LEN); 111 112 len = x25_parse_address_block(skb, &source_addr, 113 &dest_addr); 114 if (len > 0) 115 skb_pull(skb, len); 116 else if (len < 0) 117 goto out_clear; 118 119 len = x25_parse_facilities(skb, &x25->facilities, 120 &x25->dte_facilities, 121 &x25->vc_facil_mask); 122 if (len > 0) 123 skb_pull(skb, len); 124 else if (len < 0) 125 goto out_clear; 126 /* 127 * Copy any Call User Data. 128 */ 129 if (skb->len > 0) { 130 skb_copy_from_linear_data(skb, 131 x25->calluserdata.cuddata, 132 skb->len); 133 x25->calluserdata.cudlength = skb->len; 134 } 135 if (!sock_flag(sk, SOCK_DEAD)) 136 sk->sk_state_change(sk); 137 break; 138 } 139 case X25_CLEAR_REQUEST: 140 x25_write_internal(sk, X25_CLEAR_CONFIRMATION); 141 x25_disconnect(sk, ECONNREFUSED, skb->data[3], skb->data[4]); 142 break; 143 144 default: 145 break; 146 } 147 148 return 0; 149 150 out_clear: 151 x25_write_internal(sk, X25_CLEAR_REQUEST); 152 x25->state = X25_STATE_2; 153 x25_start_t23timer(sk); 154 return 0; 155 } 156 157 /* 158 * State machine for state 2, Awaiting Clear Confirmation State. 159 * The handling of the timer(s) is in file x25_timer.c 160 * Handling of state 0 and connection release is in af_x25.c. 161 */ 162 static int x25_state2_machine(struct sock *sk, struct sk_buff *skb, int frametype) 163 { 164 switch (frametype) { 165 166 case X25_CLEAR_REQUEST: 167 x25_write_internal(sk, X25_CLEAR_CONFIRMATION); 168 x25_disconnect(sk, 0, skb->data[3], skb->data[4]); 169 break; 170 171 case X25_CLEAR_CONFIRMATION: 172 x25_disconnect(sk, 0, 0, 0); 173 break; 174 175 default: 176 break; 177 } 178 179 return 0; 180 } 181 182 /* 183 * State machine for state 3, Connected State. 184 * The handling of the timer(s) is in file x25_timer.c 185 * Handling of state 0 and connection release is in af_x25.c. 186 */ 187 static int x25_state3_machine(struct sock *sk, struct sk_buff *skb, int frametype, int ns, int nr, int q, int d, int m) 188 { 189 int queued = 0; 190 int modulus; 191 struct x25_sock *x25 = x25_sk(sk); 192 193 modulus = (x25->neighbour->extended) ? X25_EMODULUS : X25_SMODULUS; 194 195 switch (frametype) { 196 197 case X25_RESET_REQUEST: 198 x25_write_internal(sk, X25_RESET_CONFIRMATION); 199 x25_stop_timer(sk); 200 x25->condition = 0x00; 201 x25->vs = 0; 202 x25->vr = 0; 203 x25->va = 0; 204 x25->vl = 0; 205 x25_requeue_frames(sk); 206 break; 207 208 case X25_CLEAR_REQUEST: 209 x25_write_internal(sk, X25_CLEAR_CONFIRMATION); 210 x25_disconnect(sk, 0, skb->data[3], skb->data[4]); 211 break; 212 213 case X25_RR: 214 case X25_RNR: 215 if (!x25_validate_nr(sk, nr)) { 216 x25_clear_queues(sk); 217 x25_write_internal(sk, X25_RESET_REQUEST); 218 x25_start_t22timer(sk); 219 x25->condition = 0x00; 220 x25->vs = 0; 221 x25->vr = 0; 222 x25->va = 0; 223 x25->vl = 0; 224 x25->state = X25_STATE_4; 225 } else { 226 x25_frames_acked(sk, nr); 227 if (frametype == X25_RNR) { 228 x25->condition |= X25_COND_PEER_RX_BUSY; 229 } else { 230 x25->condition &= ~X25_COND_PEER_RX_BUSY; 231 } 232 } 233 break; 234 235 case X25_DATA: /* XXX */ 236 x25->condition &= ~X25_COND_PEER_RX_BUSY; 237 if ((ns != x25->vr) || !x25_validate_nr(sk, nr)) { 238 x25_clear_queues(sk); 239 x25_write_internal(sk, X25_RESET_REQUEST); 240 x25_start_t22timer(sk); 241 x25->condition = 0x00; 242 x25->vs = 0; 243 x25->vr = 0; 244 x25->va = 0; 245 x25->vl = 0; 246 x25->state = X25_STATE_4; 247 break; 248 } 249 x25_frames_acked(sk, nr); 250 if (ns == x25->vr) { 251 if (x25_queue_rx_frame(sk, skb, m) == 0) { 252 x25->vr = (x25->vr + 1) % modulus; 253 queued = 1; 254 } else { 255 /* Should never happen */ 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 if (atomic_read(&sk->sk_rmem_alloc) > 268 (sk->sk_rcvbuf >> 1)) 269 x25->condition |= X25_COND_OWN_RX_BUSY; 270 } 271 /* 272 * If the window is full Ack it immediately, else 273 * start the holdback timer. 274 */ 275 if (((x25->vl + x25->facilities.winsize_in) % modulus) == x25->vr) { 276 x25->condition &= ~X25_COND_ACK_PENDING; 277 x25_stop_timer(sk); 278 x25_enquiry_response(sk); 279 } else { 280 x25->condition |= X25_COND_ACK_PENDING; 281 x25_start_t2timer(sk); 282 } 283 break; 284 285 case X25_INTERRUPT_CONFIRMATION: 286 clear_bit(X25_INTERRUPT_FLAG, &x25->flags); 287 break; 288 289 case X25_INTERRUPT: 290 if (sock_flag(sk, SOCK_URGINLINE)) 291 queued = !sock_queue_rcv_skb(sk, skb); 292 else { 293 skb_set_owner_r(skb, sk); 294 skb_queue_tail(&x25->interrupt_in_queue, skb); 295 queued = 1; 296 } 297 sk_send_sigurg(sk); 298 x25_write_internal(sk, X25_INTERRUPT_CONFIRMATION); 299 break; 300 301 default: 302 printk(KERN_WARNING "x25: unknown %02X in state 3\n", frametype); 303 break; 304 } 305 306 return queued; 307 } 308 309 /* 310 * State machine for state 4, Awaiting Reset Confirmation State. 311 * The handling of the timer(s) is in file x25_timer.c 312 * Handling of state 0 and connection release is in af_x25.c. 313 */ 314 static int x25_state4_machine(struct sock *sk, struct sk_buff *skb, int frametype) 315 { 316 switch (frametype) { 317 318 case X25_RESET_REQUEST: 319 x25_write_internal(sk, X25_RESET_CONFIRMATION); 320 case X25_RESET_CONFIRMATION: { 321 struct x25_sock *x25 = x25_sk(sk); 322 323 x25_stop_timer(sk); 324 x25->condition = 0x00; 325 x25->va = 0; 326 x25->vr = 0; 327 x25->vs = 0; 328 x25->vl = 0; 329 x25->state = X25_STATE_3; 330 x25_requeue_frames(sk); 331 break; 332 } 333 case X25_CLEAR_REQUEST: 334 x25_write_internal(sk, X25_CLEAR_CONFIRMATION); 335 x25_disconnect(sk, 0, skb->data[3], skb->data[4]); 336 break; 337 338 default: 339 break; 340 } 341 342 return 0; 343 } 344 345 /* Higher level upcall for a LAPB frame */ 346 int x25_process_rx_frame(struct sock *sk, struct sk_buff *skb) 347 { 348 struct x25_sock *x25 = x25_sk(sk); 349 int queued = 0, frametype, ns, nr, q, d, m; 350 351 if (x25->state == X25_STATE_0) 352 return 0; 353 354 frametype = x25_decode(sk, skb, &ns, &nr, &q, &d, &m); 355 356 switch (x25->state) { 357 case X25_STATE_1: 358 queued = x25_state1_machine(sk, skb, frametype); 359 break; 360 case X25_STATE_2: 361 queued = x25_state2_machine(sk, skb, frametype); 362 break; 363 case X25_STATE_3: 364 queued = x25_state3_machine(sk, skb, frametype, ns, nr, q, d, m); 365 break; 366 case X25_STATE_4: 367 queued = x25_state4_machine(sk, skb, frametype); 368 break; 369 } 370 371 x25_kick(sk); 372 373 return queued; 374 } 375 376 int x25_backlog_rcv(struct sock *sk, struct sk_buff *skb) 377 { 378 int queued = x25_process_rx_frame(sk, skb); 379 380 if (!queued) 381 kfree_skb(skb); 382 383 return 0; 384 } 385