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 95 switch (frametype) { 96 case X25_CALL_ACCEPTED: { 97 struct x25_sock *x25 = x25_sk(sk); 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); 116 117 len = x25_parse_facilities(skb, &x25->facilities, 118 &x25->dte_facilities, 119 &x25->vc_facil_mask); 120 if (len > 0) 121 skb_pull(skb, len); 122 /* 123 * Copy any Call User Data. 124 */ 125 if (skb->len > 0) { 126 skb_copy_from_linear_data(skb, 127 x25->calluserdata.cuddata, 128 skb->len); 129 x25->calluserdata.cudlength = skb->len; 130 } 131 if (!sock_flag(sk, SOCK_DEAD)) 132 sk->sk_state_change(sk); 133 break; 134 } 135 case X25_CLEAR_REQUEST: 136 x25_write_internal(sk, X25_CLEAR_CONFIRMATION); 137 x25_disconnect(sk, ECONNREFUSED, skb->data[3], skb->data[4]); 138 break; 139 140 default: 141 break; 142 } 143 144 return 0; 145 } 146 147 /* 148 * State machine for state 2, Awaiting Clear Confirmation State. 149 * The handling of the timer(s) is in file x25_timer.c 150 * Handling of state 0 and connection release is in af_x25.c. 151 */ 152 static int x25_state2_machine(struct sock *sk, struct sk_buff *skb, int frametype) 153 { 154 switch (frametype) { 155 156 case X25_CLEAR_REQUEST: 157 x25_write_internal(sk, X25_CLEAR_CONFIRMATION); 158 x25_disconnect(sk, 0, skb->data[3], skb->data[4]); 159 break; 160 161 case X25_CLEAR_CONFIRMATION: 162 x25_disconnect(sk, 0, 0, 0); 163 break; 164 165 default: 166 break; 167 } 168 169 return 0; 170 } 171 172 /* 173 * State machine for state 3, Connected State. 174 * The handling of the timer(s) is in file x25_timer.c 175 * Handling of state 0 and connection release is in af_x25.c. 176 */ 177 static int x25_state3_machine(struct sock *sk, struct sk_buff *skb, int frametype, int ns, int nr, int q, int d, int m) 178 { 179 int queued = 0; 180 int modulus; 181 struct x25_sock *x25 = x25_sk(sk); 182 183 modulus = (x25->neighbour->extended) ? X25_EMODULUS : X25_SMODULUS; 184 185 switch (frametype) { 186 187 case X25_RESET_REQUEST: 188 x25_write_internal(sk, X25_RESET_CONFIRMATION); 189 x25_stop_timer(sk); 190 x25->condition = 0x00; 191 x25->vs = 0; 192 x25->vr = 0; 193 x25->va = 0; 194 x25->vl = 0; 195 x25_requeue_frames(sk); 196 break; 197 198 case X25_CLEAR_REQUEST: 199 x25_write_internal(sk, X25_CLEAR_CONFIRMATION); 200 x25_disconnect(sk, 0, skb->data[3], skb->data[4]); 201 break; 202 203 case X25_RR: 204 case X25_RNR: 205 if (!x25_validate_nr(sk, nr)) { 206 x25_clear_queues(sk); 207 x25_write_internal(sk, X25_RESET_REQUEST); 208 x25_start_t22timer(sk); 209 x25->condition = 0x00; 210 x25->vs = 0; 211 x25->vr = 0; 212 x25->va = 0; 213 x25->vl = 0; 214 x25->state = X25_STATE_4; 215 } else { 216 x25_frames_acked(sk, nr); 217 if (frametype == X25_RNR) { 218 x25->condition |= X25_COND_PEER_RX_BUSY; 219 } else { 220 x25->condition &= ~X25_COND_PEER_RX_BUSY; 221 } 222 } 223 break; 224 225 case X25_DATA: /* XXX */ 226 x25->condition &= ~X25_COND_PEER_RX_BUSY; 227 if ((ns != x25->vr) || !x25_validate_nr(sk, nr)) { 228 x25_clear_queues(sk); 229 x25_write_internal(sk, X25_RESET_REQUEST); 230 x25_start_t22timer(sk); 231 x25->condition = 0x00; 232 x25->vs = 0; 233 x25->vr = 0; 234 x25->va = 0; 235 x25->vl = 0; 236 x25->state = X25_STATE_4; 237 break; 238 } 239 x25_frames_acked(sk, nr); 240 if (ns == x25->vr) { 241 if (x25_queue_rx_frame(sk, skb, m) == 0) { 242 x25->vr = (x25->vr + 1) % modulus; 243 queued = 1; 244 } else { 245 /* Should never happen */ 246 x25_clear_queues(sk); 247 x25_write_internal(sk, X25_RESET_REQUEST); 248 x25_start_t22timer(sk); 249 x25->condition = 0x00; 250 x25->vs = 0; 251 x25->vr = 0; 252 x25->va = 0; 253 x25->vl = 0; 254 x25->state = X25_STATE_4; 255 break; 256 } 257 if (atomic_read(&sk->sk_rmem_alloc) > 258 (sk->sk_rcvbuf >> 1)) 259 x25->condition |= X25_COND_OWN_RX_BUSY; 260 } 261 /* 262 * If the window is full Ack it immediately, else 263 * start the holdback timer. 264 */ 265 if (((x25->vl + x25->facilities.winsize_in) % modulus) == x25->vr) { 266 x25->condition &= ~X25_COND_ACK_PENDING; 267 x25_stop_timer(sk); 268 x25_enquiry_response(sk); 269 } else { 270 x25->condition |= X25_COND_ACK_PENDING; 271 x25_start_t2timer(sk); 272 } 273 break; 274 275 case X25_INTERRUPT_CONFIRMATION: 276 clear_bit(X25_INTERRUPT_FLAG, &x25->flags); 277 break; 278 279 case X25_INTERRUPT: 280 if (sock_flag(sk, SOCK_URGINLINE)) 281 queued = !sock_queue_rcv_skb(sk, skb); 282 else { 283 skb_set_owner_r(skb, sk); 284 skb_queue_tail(&x25->interrupt_in_queue, skb); 285 queued = 1; 286 } 287 sk_send_sigurg(sk); 288 x25_write_internal(sk, X25_INTERRUPT_CONFIRMATION); 289 break; 290 291 default: 292 printk(KERN_WARNING "x25: unknown %02X in state 3\n", frametype); 293 break; 294 } 295 296 return queued; 297 } 298 299 /* 300 * State machine for state 4, Awaiting Reset Confirmation State. 301 * The handling of the timer(s) is in file x25_timer.c 302 * Handling of state 0 and connection release is in af_x25.c. 303 */ 304 static int x25_state4_machine(struct sock *sk, struct sk_buff *skb, int frametype) 305 { 306 switch (frametype) { 307 308 case X25_RESET_REQUEST: 309 x25_write_internal(sk, X25_RESET_CONFIRMATION); 310 case X25_RESET_CONFIRMATION: { 311 struct x25_sock *x25 = x25_sk(sk); 312 313 x25_stop_timer(sk); 314 x25->condition = 0x00; 315 x25->va = 0; 316 x25->vr = 0; 317 x25->vs = 0; 318 x25->vl = 0; 319 x25->state = X25_STATE_3; 320 x25_requeue_frames(sk); 321 break; 322 } 323 case X25_CLEAR_REQUEST: 324 x25_write_internal(sk, X25_CLEAR_CONFIRMATION); 325 x25_disconnect(sk, 0, skb->data[3], skb->data[4]); 326 break; 327 328 default: 329 break; 330 } 331 332 return 0; 333 } 334 335 /* Higher level upcall for a LAPB frame */ 336 int x25_process_rx_frame(struct sock *sk, struct sk_buff *skb) 337 { 338 struct x25_sock *x25 = x25_sk(sk); 339 int queued = 0, frametype, ns, nr, q, d, m; 340 341 if (x25->state == X25_STATE_0) 342 return 0; 343 344 frametype = x25_decode(sk, skb, &ns, &nr, &q, &d, &m); 345 346 switch (x25->state) { 347 case X25_STATE_1: 348 queued = x25_state1_machine(sk, skb, frametype); 349 break; 350 case X25_STATE_2: 351 queued = x25_state2_machine(sk, skb, frametype); 352 break; 353 case X25_STATE_3: 354 queued = x25_state3_machine(sk, skb, frametype, ns, nr, q, d, m); 355 break; 356 case X25_STATE_4: 357 queued = x25_state4_machine(sk, skb, frametype); 358 break; 359 } 360 361 x25_kick(sk); 362 363 return queued; 364 } 365 366 int x25_backlog_rcv(struct sock *sk, struct sk_buff *skb) 367 { 368 int queued = x25_process_rx_frame(sk, skb); 369 370 if (!queued) 371 kfree_skb(skb); 372 373 return 0; 374 } 375