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                 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 }