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         int len;
  93
  94         switch (frametype) {
  95                 case X25_CALL_ACCEPTED: {
  96                         struct x25_sock *x25 = x25_sk(sk);
  97
  98                         x25_stop_timer(sk);
  99                         x25->condition = 0x00;
 100                         x25->vs        = 0;
 101                         x25->va        = 0;
 102                         x25->vr        = 0;
 103                         x25->vl        = 0;
 104                         x25->state     = X25_STATE_3;
 105                         sk->sk_state   = TCP_ESTABLISHED;
 106                         /*
 107                          *      Parse the data in the frame.
 108                          */
 109                         skb_pull(skb, X25_STD_MIN_LEN);
 110
 111                         len = x25_parse_address_block(skb, &source_addr,
 112                                                 &dest_addr);
 113                         if (len > 0)
 114                                 skb_pull(skb, len);
 115
 116                         len = x25_parse_facilities(skb, &x25->facilities,
 117                                                 &x25->dte_facilities,
 118                                                 &x25->vc_facil_mask);
 119                         if (len > 0)
 120                                 skb_pull(skb, len);
 121                         else
 122                                 return -1;
 123                         /*
 124                          *      Copy any Call User Data.
 125                          */
 126                         if (skb->len >= 0) {
 127                                 skb_copy_from_linear_data(skb,
 128                                               x25->calluserdata.cuddata,
 129                                               skb->len);
 130                                 x25->calluserdata.cudlength = skb->len;
 131                         }
 132                         if (!sock_flag(sk, SOCK_DEAD))
 133                                 sk->sk_state_change(sk);
 134                         break;
 135                 }
 136                 case X25_CLEAR_REQUEST:
 137                         x25_write_internal(sk, X25_CLEAR_CONFIRMATION);
 138                         x25_disconnect(sk, ECONNREFUSED, skb->data[3], skb->data[4]);
 139                         break;
 140
 141                 default:
 142                         break;
 143         }
 144
 145         return 0;
 146 }
 147
 148 /*
 149  * State machine for state 2, Awaiting Clear Confirmation State.
 150  * The handling of the timer(s) is in file x25_timer.c
 151  * Handling of state 0 and connection release is in af_x25.c.
 152  */
 153 static int x25_state2_machine(struct sock *sk, struct sk_buff *skb, int frametype)
 154 {
 155         switch (frametype) {
 156
 157                 case X25_CLEAR_REQUEST:
 158                         x25_write_internal(sk, X25_CLEAR_CONFIRMATION);
 159                         x25_disconnect(sk, 0, skb->data[3], skb->data[4]);
 160                         break;
 161
 162                 case X25_CLEAR_CONFIRMATION:
 163                         x25_disconnect(sk, 0, 0, 0);
 164                         break;
 165
 166                 default:
 167                         break;
 168         }
 169
 170         return 0;
 171 }
 172
 173 /*
 174  * State machine for state 3, Connected State.
 175  * The handling of the timer(s) is in file x25_timer.c
 176  * Handling of state 0 and connection release is in af_x25.c.
 177  */
 178 static int x25_state3_machine(struct sock *sk, struct sk_buff *skb, int frametype, int ns, int nr, int q, int d, int m)
 179 {
 180         int queued = 0;
 181         int modulus;
 182         struct x25_sock *x25 = x25_sk(sk);
 183
 184         modulus = (x25->neighbour->extended) ? X25_EMODULUS : X25_SMODULUS;
 185
 186         switch (frametype) {
 187
 188                 case X25_RESET_REQUEST:
 189                         x25_write_internal(sk, X25_RESET_CONFIRMATION);
 190                         x25_stop_timer(sk);
 191                         x25->condition = 0x00;
 192                         x25->vs        = 0;
 193                         x25->vr        = 0;
 194                         x25->va        = 0;
 195                         x25->vl        = 0;
 196                         x25_requeue_frames(sk);
 197                         break;
 198
 199                 case X25_CLEAR_REQUEST:
 200                         x25_write_internal(sk, X25_CLEAR_CONFIRMATION);
 201                         x25_disconnect(sk, 0, skb->data[3], skb->data[4]);
 202                         break;
 203
 204                 case X25_RR:
 205                 case X25_RNR:
 206                         if (!x25_validate_nr(sk, nr)) {
 207                                 x25_clear_queues(sk);
 208                                 x25_write_internal(sk, X25_RESET_REQUEST);
 209                                 x25_start_t22timer(sk);
 210                                 x25->condition = 0x00;
 211                                 x25->vs        = 0;
 212                                 x25->vr        = 0;
 213                                 x25->va        = 0;
 214                                 x25->vl        = 0;
 215                                 x25->state     = X25_STATE_4;
 216                         } else {
 217                                 x25_frames_acked(sk, nr);
 218                                 if (frametype == X25_RNR) {
 219                                         x25->condition |= X25_COND_PEER_RX_BUSY;
 220                                 } else {
 221                                         x25->condition &= ~X25_COND_PEER_RX_BUSY;
 222                                 }
 223                         }
 224                         break;
 225
 226                 case X25_DATA:  /* XXX */
 227                         x25->condition &= ~X25_COND_PEER_RX_BUSY;
 228                         if ((ns != x25->vr) || !x25_validate_nr(sk, nr)) {
 229                                 x25_clear_queues(sk);
 230                                 x25_write_internal(sk, X25_RESET_REQUEST);
 231                                 x25_start_t22timer(sk);
 232                                 x25->condition = 0x00;
 233                                 x25->vs        = 0;
 234                                 x25->vr        = 0;
 235                                 x25->va        = 0;
 236                                 x25->vl        = 0;
 237                                 x25->state     = X25_STATE_4;
 238                                 break;
 239                         }
 240                         x25_frames_acked(sk, nr);
 241                         if (ns == x25->vr) {
 242                                 if (x25_queue_rx_frame(sk, skb, m) == 0) {
 243                                         x25->vr = (x25->vr + 1) % modulus;
 244                                         queued = 1;
 245                                 } else {
 246                                         /* Should never happen */
 247                                         x25_clear_queues(sk);
 248                                         x25_write_internal(sk, X25_RESET_REQUEST);
 249                                         x25_start_t22timer(sk);
 250                                         x25->condition = 0x00;
 251                                         x25->vs        = 0;
 252                                         x25->vr        = 0;
 253                                         x25->va        = 0;
 254                                         x25->vl        = 0;
 255                                         x25->state     = X25_STATE_4;
 256                                         break;
 257                                 }
 258                                 if (atomic_read(&sk->sk_rmem_alloc) >
 259                                     (sk->sk_rcvbuf >> 1))
 260                                         x25->condition |= X25_COND_OWN_RX_BUSY;
 261                         }
 262                         /*
 263                          *      If the window is full Ack it immediately, else
 264                          *      start the holdback timer.
 265                          */
 266                         if (((x25->vl + x25->facilities.winsize_in) % modulus) == x25->vr) {
 267                                 x25->condition &= ~X25_COND_ACK_PENDING;
 268                                 x25_stop_timer(sk);
 269                                 x25_enquiry_response(sk);
 270                         } else {
 271                                 x25->condition |= X25_COND_ACK_PENDING;
 272                                 x25_start_t2timer(sk);
 273                         }
 274                         break;
 275
 276                 case X25_INTERRUPT_CONFIRMATION:
 277                         x25->intflag = 0;
 278                         break;
 279
 280                 case X25_INTERRUPT:
 281                         if (sock_flag(sk, SOCK_URGINLINE))
 282                                 queued = !sock_queue_rcv_skb(sk, skb);
 283                         else {
 284                                 skb_set_owner_r(skb, sk);
 285                                 skb_queue_tail(&x25->interrupt_in_queue, skb);
 286                                 queued = 1;
 287                         }
 288                         sk_send_sigurg(sk);
 289                         x25_write_internal(sk, X25_INTERRUPT_CONFIRMATION);
 290                         break;
 291
 292                 default:
 293                         printk(KERN_WARNING "x25: unknown %02X in state 3\n", frametype);
 294                         break;
 295         }
 296
 297         return queued;
 298 }
 299
 300 /*
 301  * State machine for state 4, Awaiting Reset Confirmation State.
 302  * The handling of the timer(s) is in file x25_timer.c
 303  * Handling of state 0 and connection release is in af_x25.c.
 304  */
 305 static int x25_state4_machine(struct sock *sk, struct sk_buff *skb, int frametype)
 306 {
 307         switch (frametype) {
 308
 309                 case X25_RESET_REQUEST:
 310                         x25_write_internal(sk, X25_RESET_CONFIRMATION);
 311                 case X25_RESET_CONFIRMATION: {
 312                         struct x25_sock *x25 = x25_sk(sk);
 313
 314                         x25_stop_timer(sk);
 315                         x25->condition = 0x00;
 316                         x25->va        = 0;
 317                         x25->vr        = 0;
 318                         x25->vs        = 0;
 319                         x25->vl        = 0;
 320                         x25->state     = X25_STATE_3;
 321                         x25_requeue_frames(sk);
 322                         break;
 323                 }
 324                 case X25_CLEAR_REQUEST:
 325                         x25_write_internal(sk, X25_CLEAR_CONFIRMATION);
 326                         x25_disconnect(sk, 0, skb->data[3], skb->data[4]);
 327                         break;
 328
 329                 default:
 330                         break;
 331         }
 332
 333         return 0;
 334 }
 335
 336 /* Higher level upcall for a LAPB frame */
 337 int x25_process_rx_frame(struct sock *sk, struct sk_buff *skb)
 338 {
 339         struct x25_sock *x25 = x25_sk(sk);
 340         int queued = 0, frametype, ns, nr, q, d, m;
 341
 342         if (x25->state == X25_STATE_0)
 343                 return 0;
 344
 345         frametype = x25_decode(sk, skb, &ns, &nr, &q, &d, &m);
 346
 347         switch (x25->state) {
 348                 case X25_STATE_1:
 349                         queued = x25_state1_machine(sk, skb, frametype);
 350                         break;
 351                 case X25_STATE_2:
 352                         queued = x25_state2_machine(sk, skb, frametype);
 353                         break;
 354                 case X25_STATE_3:
 355                         queued = x25_state3_machine(sk, skb, frametype, ns, nr, q, d, m);
 356                         break;
 357                 case X25_STATE_4:
 358                         queued = x25_state4_machine(sk, skb, frametype);
 359                         break;
 360         }
 361
 362         x25_kick(sk);
 363
 364         return queued;
 365 }
 366
 367 int x25_backlog_rcv(struct sock *sk, struct sk_buff *skb)
 368 {
 369         int queued = x25_process_rx_frame(sk, skb);
 370
 371         if (!queued)
 372                 kfree_skb(skb);
 373
 374         return 0;
 375 }