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
  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                         else
 123                                 return -1;
 124                         /*
 125                          *      Copy any Call User Data.
 126                          */
 127                         if (skb->len > 0) {
 128                                 skb_copy_from_linear_data(skb,
 129                                               x25->calluserdata.cuddata,
 130                                               skb->len);
 131                                 x25->calluserdata.cudlength = skb->len;
 132                         }
 133                         if (!sock_flag(sk, SOCK_DEAD))
 134                                 sk->sk_state_change(sk);
 135                         break;
 136                 }
 137                 case X25_CLEAR_REQUEST:
 138                         x25_write_internal(sk, X25_CLEAR_CONFIRMATION);
 139                         x25_disconnect(sk, ECONNREFUSED, skb->data[3], skb->data[4]);
 140                         break;
 141
 142                 default:
 143                         break;
 144         }
 145
 146         return 0;
 147 }
 148
 149 /*
 150  * State machine for state 2, Awaiting Clear Confirmation State.
 151  * The handling of the timer(s) is in file x25_timer.c
 152  * Handling of state 0 and connection release is in af_x25.c.
 153  */
 154 static int x25_state2_machine(struct sock *sk, struct sk_buff *skb, int frametype)
 155 {
 156         switch (frametype) {
 157
 158                 case X25_CLEAR_REQUEST:
 159                         x25_write_internal(sk, X25_CLEAR_CONFIRMATION);
 160                         x25_disconnect(sk, 0, skb->data[3], skb->data[4]);
 161                         break;
 162
 163                 case X25_CLEAR_CONFIRMATION:
 164                         x25_disconnect(sk, 0, 0, 0);
 165                         break;
 166
 167                 default:
 168                         break;
 169         }
 170
 171         return 0;
 172 }
 173
 174 /*
 175  * State machine for state 3, Connected State.
 176  * The handling of the timer(s) is in file x25_timer.c
 177  * Handling of state 0 and connection release is in af_x25.c.
 178  */
 179 static int x25_state3_machine(struct sock *sk, struct sk_buff *skb, int frametype, int ns, int nr, int q, int d, int m)
 180 {
 181         int queued = 0;
 182         int modulus;
 183         struct x25_sock *x25 = x25_sk(sk);
 184
 185         modulus = (x25->neighbour->extended) ? X25_EMODULUS : X25_SMODULUS;
 186
 187         switch (frametype) {
 188
 189                 case X25_RESET_REQUEST:
 190                         x25_write_internal(sk, X25_RESET_CONFIRMATION);
 191                         x25_stop_timer(sk);
 192                         x25->condition = 0x00;
 193                         x25->vs        = 0;
 194                         x25->vr        = 0;
 195                         x25->va        = 0;
 196                         x25->vl        = 0;
 197                         x25_requeue_frames(sk);
 198                         break;
 199
 200                 case X25_CLEAR_REQUEST:
 201                         x25_write_internal(sk, X25_CLEAR_CONFIRMATION);
 202                         x25_disconnect(sk, 0, skb->data[3], skb->data[4]);
 203                         break;
 204
 205                 case X25_RR:
 206                 case X25_RNR:
 207                         if (!x25_validate_nr(sk, nr)) {
 208                                 x25_clear_queues(sk);
 209                                 x25_write_internal(sk, X25_RESET_REQUEST);
 210                                 x25_start_t22timer(sk);
 211                                 x25->condition = 0x00;
 212                                 x25->vs        = 0;
 213                                 x25->vr        = 0;
 214                                 x25->va        = 0;
 215                                 x25->vl        = 0;
 216                                 x25->state     = X25_STATE_4;
 217                         } else {
 218                                 x25_frames_acked(sk, nr);
 219                                 if (frametype == X25_RNR) {
 220                                         x25->condition |= X25_COND_PEER_RX_BUSY;
 221                                 } else {
 222                                         x25->condition &= ~X25_COND_PEER_RX_BUSY;
 223                                 }
 224                         }
 225                         break;
 226
 227                 case X25_DATA:  /* XXX */
 228                         x25->condition &= ~X25_COND_PEER_RX_BUSY;
 229                         if ((ns != x25->vr) || !x25_validate_nr(sk, nr)) {
 230                                 x25_clear_queues(sk);
 231                                 x25_write_internal(sk, X25_RESET_REQUEST);
 232                                 x25_start_t22timer(sk);
 233                                 x25->condition = 0x00;
 234                                 x25->vs        = 0;
 235                                 x25->vr        = 0;
 236                                 x25->va        = 0;
 237                                 x25->vl        = 0;
 238                                 x25->state     = X25_STATE_4;
 239                                 break;
 240                         }
 241                         x25_frames_acked(sk, nr);
 242                         if (ns == x25->vr) {
 243                                 if (x25_queue_rx_frame(sk, skb, m) == 0) {
 244                                         x25->vr = (x25->vr + 1) % modulus;
 245                                         queued = 1;
 246                                 } else {
 247                                         /* Should never happen */
 248                                         x25_clear_queues(sk);
 249                                         x25_write_internal(sk, X25_RESET_REQUEST);
 250                                         x25_start_t22timer(sk);
 251                                         x25->condition = 0x00;
 252                                         x25->vs        = 0;
 253                                         x25->vr        = 0;
 254                                         x25->va        = 0;
 255                                         x25->vl        = 0;
 256                                         x25->state     = X25_STATE_4;
 257                                         break;
 258                                 }
 259                                 if (atomic_read(&sk->sk_rmem_alloc) >
 260                                     (sk->sk_rcvbuf >> 1))
 261                                         x25->condition |= X25_COND_OWN_RX_BUSY;
 262                         }
 263                         /*
 264                          *      If the window is full Ack it immediately, else
 265                          *      start the holdback timer.
 266                          */
 267                         if (((x25->vl + x25->facilities.winsize_in) % modulus) == x25->vr) {
 268                                 x25->condition &= ~X25_COND_ACK_PENDING;
 269                                 x25_stop_timer(sk);
 270                                 x25_enquiry_response(sk);
 271                         } else {
 272                                 x25->condition |= X25_COND_ACK_PENDING;
 273                                 x25_start_t2timer(sk);
 274                         }
 275                         break;
 276
 277                 case X25_INTERRUPT_CONFIRMATION:
 278                         clear_bit(X25_INTERRUPT_FLAG, &x25->flags);
 279                         break;
 280
 281                 case X25_INTERRUPT:
 282                         if (sock_flag(sk, SOCK_URGINLINE))
 283                                 queued = !sock_queue_rcv_skb(sk, skb);
 284                         else {
 285                                 skb_set_owner_r(skb, sk);
 286                                 skb_queue_tail(&x25->interrupt_in_queue, skb);
 287                                 queued = 1;
 288                         }
 289                         sk_send_sigurg(sk);
 290                         x25_write_internal(sk, X25_INTERRUPT_CONFIRMATION);
 291                         break;
 292
 293                 default:
 294                         printk(KERN_WARNING "x25: unknown %02X in state 3\n", frametype);
 295                         break;
 296         }
 297
 298         return queued;
 299 }
 300
 301 /*
 302  * State machine for state 4, Awaiting Reset Confirmation State.
 303  * The handling of the timer(s) is in file x25_timer.c
 304  * Handling of state 0 and connection release is in af_x25.c.
 305  */
 306 static int x25_state4_machine(struct sock *sk, struct sk_buff *skb, int frametype)
 307 {
 308         switch (frametype) {
 309
 310                 case X25_RESET_REQUEST:
 311                         x25_write_internal(sk, X25_RESET_CONFIRMATION);
 312                 case X25_RESET_CONFIRMATION: {
 313                         struct x25_sock *x25 = x25_sk(sk);
 314
 315                         x25_stop_timer(sk);
 316                         x25->condition = 0x00;
 317                         x25->va        = 0;
 318                         x25->vr        = 0;
 319                         x25->vs        = 0;
 320                         x25->vl        = 0;
 321                         x25->state     = X25_STATE_3;
 322                         x25_requeue_frames(sk);
 323                         break;
 324                 }
 325                 case X25_CLEAR_REQUEST:
 326                         x25_write_internal(sk, X25_CLEAR_CONFIRMATION);
 327                         x25_disconnect(sk, 0, skb->data[3], skb->data[4]);
 328                         break;
 329
 330                 default:
 331                         break;
 332         }
 333
 334         return 0;
 335 }
 336
 337 /* Higher level upcall for a LAPB frame */
 338 int x25_process_rx_frame(struct sock *sk, struct sk_buff *skb)
 339 {
 340         struct x25_sock *x25 = x25_sk(sk);
 341         int queued = 0, frametype, ns, nr, q, d, m;
 342
 343         if (x25->state == X25_STATE_0)
 344                 return 0;
 345
 346         frametype = x25_decode(sk, skb, &ns, &nr, &q, &d, &m);
 347
 348         switch (x25->state) {
 349                 case X25_STATE_1:
 350                         queued = x25_state1_machine(sk, skb, frametype);
 351                         break;
 352                 case X25_STATE_2:
 353                         queued = x25_state2_machine(sk, skb, frametype);
 354                         break;
 355                 case X25_STATE_3:
 356                         queued = x25_state3_machine(sk, skb, frametype, ns, nr, q, d, m);
 357                         break;
 358                 case X25_STATE_4:
 359                         queued = x25_state4_machine(sk, skb, frametype);
 360                         break;
 361         }
 362
 363         x25_kick(sk);
 364
 365         return queued;
 366 }
 367
 368 int x25_backlog_rcv(struct sock *sk, struct sk_buff *skb)
 369 {
 370         int queued = x25_process_rx_frame(sk, skb);
 371
 372         if (!queued)
 373                 kfree_skb(skb);
 374
 375         return 0;
 376 }