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/errno.h>
  27 #include <linux/kernel.h>
  28 #include <linux/string.h>
  29 #include <linux/skbuff.h>
  30 #include <net/sock.h>
  31 #include <net/tcp_states.h>
  32 #include <net/x25.h>
  33
  34 static int x25_queue_rx_frame(struct sock *sk, struct sk_buff *skb, int more)
  35 {
  36         struct sk_buff *skbo, *skbn = skb;
  37         struct x25_sock *x25 = x25_sk(sk);
  38
  39         if (more) {
  40                 x25->fraglen += skb->len;
  41                 skb_queue_tail(&x25->fragment_queue, skb);
  42                 skb_set_owner_r(skb, sk);
  43                 return 0;
  44         }
  45
  46         if (!more && x25->fraglen > 0) {        /* End of fragment */
  47                 int len = x25->fraglen + skb->len;
  48
  49                 if ((skbn = alloc_skb(len, GFP_ATOMIC)) == NULL){
  50                         kfree_skb(skb);
  51                         return 1;
  52                 }
  53
  54                 skb_queue_tail(&x25->fragment_queue, skb);
  55
  56                 skb_reset_transport_header(skbn);
  57
  58                 skbo = skb_dequeue(&x25->fragment_queue);
  59                 skb_copy_from_linear_data(skbo, skb_put(skbn, skbo->len),
  60                                           skbo->len);
  61                 kfree_skb(skbo);
  62
  63                 while ((skbo =
  64                         skb_dequeue(&x25->fragment_queue)) != NULL) {
  65                         skb_pull(skbo, (x25->neighbour->extended) ?
  66                                         X25_EXT_MIN_LEN : X25_STD_MIN_LEN);
  67                         skb_copy_from_linear_data(skbo,
  68                                                   skb_put(skbn, skbo->len),
  69                                                   skbo->len);
  70                         kfree_skb(skbo);
  71                 }
  72
  73                 x25->fraglen = 0;
  74         }
  75
  76         skb_set_owner_r(skbn, sk);
  77         skb_queue_tail(&sk->sk_receive_queue, skbn);
  78         if (!sock_flag(sk, SOCK_DEAD))
  79                 sk->sk_data_ready(sk, skbn->len);
  80
  81         return 0;
  82 }
  83
  84 /*
  85  * State machine for state 1, Awaiting Call Accepted State.
  86  * The handling of the timer(s) is in file x25_timer.c.
  87  * Handling of state 0 and connection release is in af_x25.c.
  88  */
  89 static int x25_state1_machine(struct sock *sk, struct sk_buff *skb, int frametype)
  90 {
  91         struct x25_address source_addr, dest_addr;
  92
  93         switch (frametype) {
  94                 case X25_CALL_ACCEPTED: {
  95                         struct x25_sock *x25 = x25_sk(sk);
  96
  97                         x25_stop_timer(sk);
  98                         x25->condition = 0x00;
  99                         x25->vs        = 0;
 100                         x25->va        = 0;
 101                         x25->vr        = 0;
 102                         x25->vl        = 0;
 103                         x25->state     = X25_STATE_3;
 104                         sk->sk_state   = TCP_ESTABLISHED;
 105                         /*
 106                          *      Parse the data in the frame.
 107                          */
 108                         skb_pull(skb, X25_STD_MIN_LEN);
 109                         skb_pull(skb, x25_addr_ntoa(skb->data, &source_addr, &dest_addr));
 110                         skb_pull(skb,
 111                                  x25_parse_facilities(skb, &x25->facilities,
 112                                                 &x25->dte_facilities,
 113                                                 &x25->vc_facil_mask));
 114                         /*
 115                          *      Copy any Call User Data.
 116                          */
 117                         if (skb->len >= 0) {
 118                                 skb_copy_from_linear_data(skb,
 119                                               x25->calluserdata.cuddata,
 120                                               skb->len);
 121                                 x25->calluserdata.cudlength = skb->len;
 122                         }
 123                         if (!sock_flag(sk, SOCK_DEAD))
 124                                 sk->sk_state_change(sk);
 125                         break;
 126                 }
 127                 case X25_CLEAR_REQUEST:
 128                         x25_write_internal(sk, X25_CLEAR_CONFIRMATION);
 129                         x25_disconnect(sk, ECONNREFUSED, skb->data[3], skb->data[4]);
 130                         break;
 131
 132                 default:
 133                         break;
 134         }
 135
 136         return 0;
 137 }
 138
 139 /*
 140  * State machine for state 2, Awaiting Clear Confirmation State.
 141  * The handling of the timer(s) is in file x25_timer.c
 142  * Handling of state 0 and connection release is in af_x25.c.
 143  */
 144 static int x25_state2_machine(struct sock *sk, struct sk_buff *skb, int frametype)
 145 {
 146         switch (frametype) {
 147
 148                 case X25_CLEAR_REQUEST:
 149                         x25_write_internal(sk, X25_CLEAR_CONFIRMATION);
 150                         x25_disconnect(sk, 0, skb->data[3], skb->data[4]);
 151                         break;
 152
 153                 case X25_CLEAR_CONFIRMATION:
 154                         x25_disconnect(sk, 0, 0, 0);
 155                         break;
 156
 157                 default:
 158                         break;
 159         }
 160
 161         return 0;
 162 }
 163
 164 /*
 165  * State machine for state 3, Connected 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_state3_machine(struct sock *sk, struct sk_buff *skb, int frametype, int ns, int nr, int q, int d, int m)
 170 {
 171         int queued = 0;
 172         int modulus;
 173         struct x25_sock *x25 = x25_sk(sk);
 174
 175         modulus = (x25->neighbour->extended) ? X25_EMODULUS : X25_SMODULUS;
 176
 177         switch (frametype) {
 178
 179                 case X25_RESET_REQUEST:
 180                         x25_write_internal(sk, X25_RESET_CONFIRMATION);
 181                         x25_stop_timer(sk);
 182                         x25->condition = 0x00;
 183                         x25->vs        = 0;
 184                         x25->vr        = 0;
 185                         x25->va        = 0;
 186                         x25->vl        = 0;
 187                         x25_requeue_frames(sk);
 188                         break;
 189
 190                 case X25_CLEAR_REQUEST:
 191                         x25_write_internal(sk, X25_CLEAR_CONFIRMATION);
 192                         x25_disconnect(sk, 0, skb->data[3], skb->data[4]);
 193                         break;
 194
 195                 case X25_RR:
 196                 case X25_RNR:
 197                         if (!x25_validate_nr(sk, nr)) {
 198                                 x25_clear_queues(sk);
 199                                 x25_write_internal(sk, X25_RESET_REQUEST);
 200                                 x25_start_t22timer(sk);
 201                                 x25->condition = 0x00;
 202                                 x25->vs        = 0;
 203                                 x25->vr        = 0;
 204                                 x25->va        = 0;
 205                                 x25->vl        = 0;
 206                                 x25->state     = X25_STATE_4;
 207                         } else {
 208                                 x25_frames_acked(sk, nr);
 209                                 if (frametype == X25_RNR) {
 210                                         x25->condition |= X25_COND_PEER_RX_BUSY;
 211                                 } else {
 212                                         x25->condition &= ~X25_COND_PEER_RX_BUSY;
 213                                 }
 214                         }
 215                         break;
 216
 217                 case X25_DATA:  /* XXX */
 218                         x25->condition &= ~X25_COND_PEER_RX_BUSY;
 219                         if ((ns != x25->vr) || !x25_validate_nr(sk, nr)) {
 220                                 x25_clear_queues(sk);
 221                                 x25_write_internal(sk, X25_RESET_REQUEST);
 222                                 x25_start_t22timer(sk);
 223                                 x25->condition = 0x00;
 224                                 x25->vs        = 0;
 225                                 x25->vr        = 0;
 226                                 x25->va        = 0;
 227                                 x25->vl        = 0;
 228                                 x25->state     = X25_STATE_4;
 229                                 break;
 230                         }
 231                         x25_frames_acked(sk, nr);
 232                         if (ns == x25->vr) {
 233                                 if (x25_queue_rx_frame(sk, skb, m) == 0) {
 234                                         x25->vr = (x25->vr + 1) % modulus;
 235                                         queued = 1;
 236                                 } else {
 237                                         /* Should never happen */
 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                                 if (atomic_read(&sk->sk_rmem_alloc) >
 250                                     (sk->sk_rcvbuf >> 1))
 251                                         x25->condition |= X25_COND_OWN_RX_BUSY;
 252                         }
 253                         /*
 254                          *      If the window is full Ack it immediately, else
 255                          *      start the holdback timer.
 256                          */
 257                         if (((x25->vl + x25->facilities.winsize_in) % modulus) == x25->vr) {
 258                                 x25->condition &= ~X25_COND_ACK_PENDING;
 259                                 x25_stop_timer(sk);
 260                                 x25_enquiry_response(sk);
 261                         } else {
 262                                 x25->condition |= X25_COND_ACK_PENDING;
 263                                 x25_start_t2timer(sk);
 264                         }
 265                         break;
 266
 267                 case X25_INTERRUPT_CONFIRMATION:
 268                         x25->intflag = 0;
 269                         break;
 270
 271                 case X25_INTERRUPT:
 272                         if (sock_flag(sk, SOCK_URGINLINE))
 273                                 queued = !sock_queue_rcv_skb(sk, skb);
 274                         else {
 275                                 skb_set_owner_r(skb, sk);
 276                                 skb_queue_tail(&x25->interrupt_in_queue, skb);
 277                                 queued = 1;
 278                         }
 279                         sk_send_sigurg(sk);
 280                         x25_write_internal(sk, X25_INTERRUPT_CONFIRMATION);
 281                         break;
 282
 283                 default:
 284                         printk(KERN_WARNING "x25: unknown %02X in state 3\n", frametype);
 285                         break;
 286         }
 287
 288         return queued;
 289 }
 290
 291 /*
 292  * State machine for state 4, Awaiting Reset Confirmation State.
 293  * The handling of the timer(s) is in file x25_timer.c
 294  * Handling of state 0 and connection release is in af_x25.c.
 295  */
 296 static int x25_state4_machine(struct sock *sk, struct sk_buff *skb, int frametype)
 297 {
 298         switch (frametype) {
 299
 300                 case X25_RESET_REQUEST:
 301                         x25_write_internal(sk, X25_RESET_CONFIRMATION);
 302                 case X25_RESET_CONFIRMATION: {
 303                         struct x25_sock *x25 = x25_sk(sk);
 304
 305                         x25_stop_timer(sk);
 306                         x25->condition = 0x00;
 307                         x25->va        = 0;
 308                         x25->vr        = 0;
 309                         x25->vs        = 0;
 310                         x25->vl        = 0;
 311                         x25->state     = X25_STATE_3;
 312                         x25_requeue_frames(sk);
 313                         break;
 314                 }
 315                 case X25_CLEAR_REQUEST:
 316                         x25_write_internal(sk, X25_CLEAR_CONFIRMATION);
 317                         x25_disconnect(sk, 0, skb->data[3], skb->data[4]);
 318                         break;
 319
 320                 default:
 321                         break;
 322         }
 323
 324         return 0;
 325 }
 326
 327 /* Higher level upcall for a LAPB frame */
 328 int x25_process_rx_frame(struct sock *sk, struct sk_buff *skb)
 329 {
 330         struct x25_sock *x25 = x25_sk(sk);
 331         int queued = 0, frametype, ns, nr, q, d, m;
 332
 333         if (x25->state == X25_STATE_0)
 334                 return 0;
 335
 336         frametype = x25_decode(sk, skb, &ns, &nr, &q, &d, &m);
 337
 338         switch (x25->state) {
 339                 case X25_STATE_1:
 340                         queued = x25_state1_machine(sk, skb, frametype);
 341                         break;
 342                 case X25_STATE_2:
 343                         queued = x25_state2_machine(sk, skb, frametype);
 344                         break;
 345                 case X25_STATE_3:
 346                         queued = x25_state3_machine(sk, skb, frametype, ns, nr, q, d, m);
 347                         break;
 348                 case X25_STATE_4:
 349                         queued = x25_state4_machine(sk, skb, frametype);
 350                         break;
 351         }
 352
 353         x25_kick(sk);
 354
 355         return queued;
 356 }
 357
 358 int x25_backlog_rcv(struct sock *sk, struct sk_buff *skb)
 359 {
 360         int queued = x25_process_rx_frame(sk, skb);
 361
 362         if (!queued)
 363                 kfree_skb(skb);
 364
 365         return 0;
 366 }