net/x25/x25_in.c

   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 }