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                         if (skb->len > X25_MAX_CUD_LEN)
 131                                 goto out_clear;
 132
 133                         skb_copy_from_linear_data(skb,
 134                                                   x25->calluserdata.cuddata,
 135                                                   skb->len);
 136                         x25->calluserdata.cudlength = skb->len;
 137                 }
 138                 if (!sock_flag(sk, SOCK_DEAD))
 139                         sk->sk_state_change(sk);
 140                 break;
 141         }
 142         case X25_CLEAR_REQUEST:
 143                 x25_write_internal(sk, X25_CLEAR_CONFIRMATION);
 144                 x25_disconnect(sk, ECONNREFUSED, skb->data[3], skb->data[4]);
 145                 break;
 146
 147         default:
 148                 break;
 149         }
 150
 151         return 0;
 152
 153 out_clear:
 154         x25_write_internal(sk, X25_CLEAR_REQUEST);
 155         x25->state = X25_STATE_2;
 156         x25_start_t23timer(sk);
 157         return 0;
 158 }
 159
 160 /*
 161  * State machine for state 2, Awaiting Clear Confirmation State.
 162  * The handling of the timer(s) is in file x25_timer.c
 163  * Handling of state 0 and connection release is in af_x25.c.
 164  */
 165 static int x25_state2_machine(struct sock *sk, struct sk_buff *skb, int frametype)
 166 {
 167         switch (frametype) {
 168
 169                 case X25_CLEAR_REQUEST:
 170                         x25_write_internal(sk, X25_CLEAR_CONFIRMATION);
 171                         x25_disconnect(sk, 0, skb->data[3], skb->data[4]);
 172                         break;
 173
 174                 case X25_CLEAR_CONFIRMATION:
 175                         x25_disconnect(sk, 0, 0, 0);
 176                         break;
 177
 178                 default:
 179                         break;
 180         }
 181
 182         return 0;
 183 }
 184
 185 /*
 186  * State machine for state 3, Connected State.
 187  * The handling of the timer(s) is in file x25_timer.c
 188  * Handling of state 0 and connection release is in af_x25.c.
 189  */
 190 static int x25_state3_machine(struct sock *sk, struct sk_buff *skb, int frametype, int ns, int nr, int q, int d, int m)
 191 {
 192         int queued = 0;
 193         int modulus;
 194         struct x25_sock *x25 = x25_sk(sk);
 195
 196         modulus = (x25->neighbour->extended) ? X25_EMODULUS : X25_SMODULUS;
 197
 198         switch (frametype) {
 199
 200                 case X25_RESET_REQUEST:
 201                         x25_write_internal(sk, X25_RESET_CONFIRMATION);
 202                         x25_stop_timer(sk);
 203                         x25->condition = 0x00;
 204                         x25->vs        = 0;
 205                         x25->vr        = 0;
 206                         x25->va        = 0;
 207                         x25->vl        = 0;
 208                         x25_requeue_frames(sk);
 209                         break;
 210
 211                 case X25_CLEAR_REQUEST:
 212                         x25_write_internal(sk, X25_CLEAR_CONFIRMATION);
 213                         x25_disconnect(sk, 0, skb->data[3], skb->data[4]);
 214                         break;
 215
 216                 case X25_RR:
 217                 case X25_RNR:
 218                         if (!x25_validate_nr(sk, nr)) {
 219                                 x25_clear_queues(sk);
 220                                 x25_write_internal(sk, X25_RESET_REQUEST);
 221                                 x25_start_t22timer(sk);
 222                                 x25->condition = 0x00;
 223                                 x25->vs        = 0;
 224                                 x25->vr        = 0;
 225                                 x25->va        = 0;
 226                                 x25->vl        = 0;
 227                                 x25->state     = X25_STATE_4;
 228                         } else {
 229                                 x25_frames_acked(sk, nr);
 230                                 if (frametype == X25_RNR) {
 231                                         x25->condition |= X25_COND_PEER_RX_BUSY;
 232                                 } else {
 233                                         x25->condition &= ~X25_COND_PEER_RX_BUSY;
 234                                 }
 235                         }
 236                         break;
 237
 238                 case X25_DATA:  /* XXX */
 239                         x25->condition &= ~X25_COND_PEER_RX_BUSY;
 240                         if ((ns != x25->vr) || !x25_validate_nr(sk, nr)) {
 241                                 x25_clear_queues(sk);
 242                                 x25_write_internal(sk, X25_RESET_REQUEST);
 243                                 x25_start_t22timer(sk);
 244                                 x25->condition = 0x00;
 245                                 x25->vs        = 0;
 246                                 x25->vr        = 0;
 247                                 x25->va        = 0;
 248                                 x25->vl        = 0;
 249                                 x25->state     = X25_STATE_4;
 250                                 break;
 251                         }
 252                         x25_frames_acked(sk, nr);
 253                         if (ns == x25->vr) {
 254                                 if (x25_queue_rx_frame(sk, skb, m) == 0) {
 255                                         x25->vr = (x25->vr + 1) % modulus;
 256                                         queued = 1;
 257                                 } else {
 258                                         /* Should never happen */
 259                                         x25_clear_queues(sk);
 260                                         x25_write_internal(sk, X25_RESET_REQUEST);
 261                                         x25_start_t22timer(sk);
 262                                         x25->condition = 0x00;
 263                                         x25->vs        = 0;
 264                                         x25->vr        = 0;
 265                                         x25->va        = 0;
 266                                         x25->vl        = 0;
 267                                         x25->state     = X25_STATE_4;
 268                                         break;
 269                                 }
 270                                 if (atomic_read(&sk->sk_rmem_alloc) >
 271                                     (sk->sk_rcvbuf >> 1))
 272                                         x25->condition |= X25_COND_OWN_RX_BUSY;
 273                         }
 274                         /*
 275                          *      If the window is full Ack it immediately, else
 276                          *      start the holdback timer.
 277                          */
 278                         if (((x25->vl + x25->facilities.winsize_in) % modulus) == x25->vr) {
 279                                 x25->condition &= ~X25_COND_ACK_PENDING;
 280                                 x25_stop_timer(sk);
 281                                 x25_enquiry_response(sk);
 282                         } else {
 283                                 x25->condition |= X25_COND_ACK_PENDING;
 284                                 x25_start_t2timer(sk);
 285                         }
 286                         break;
 287
 288                 case X25_INTERRUPT_CONFIRMATION:
 289                         clear_bit(X25_INTERRUPT_FLAG, &x25->flags);
 290                         break;
 291
 292                 case X25_INTERRUPT:
 293                         if (sock_flag(sk, SOCK_URGINLINE))
 294                                 queued = !sock_queue_rcv_skb(sk, skb);
 295                         else {
 296                                 skb_set_owner_r(skb, sk);
 297                                 skb_queue_tail(&x25->interrupt_in_queue, skb);
 298                                 queued = 1;
 299                         }
 300                         sk_send_sigurg(sk);
 301                         x25_write_internal(sk, X25_INTERRUPT_CONFIRMATION);
 302                         break;
 303
 304                 default:
 305                         printk(KERN_WARNING "x25: unknown %02X in state 3\n", frametype);
 306                         break;
 307         }
 308
 309         return queued;
 310 }
 311
 312 /*
 313  * State machine for state 4, Awaiting Reset Confirmation State.
 314  * The handling of the timer(s) is in file x25_timer.c
 315  * Handling of state 0 and connection release is in af_x25.c.
 316  */
 317 static int x25_state4_machine(struct sock *sk, struct sk_buff *skb, int frametype)
 318 {
 319         switch (frametype) {
 320
 321                 case X25_RESET_REQUEST:
 322                         x25_write_internal(sk, X25_RESET_CONFIRMATION);
 323                 case X25_RESET_CONFIRMATION: {
 324                         struct x25_sock *x25 = x25_sk(sk);
 325
 326                         x25_stop_timer(sk);
 327                         x25->condition = 0x00;
 328                         x25->va        = 0;
 329                         x25->vr        = 0;
 330                         x25->vs        = 0;
 331                         x25->vl        = 0;
 332                         x25->state     = X25_STATE_3;
 333                         x25_requeue_frames(sk);
 334                         break;
 335                 }
 336                 case X25_CLEAR_REQUEST:
 337                         x25_write_internal(sk, X25_CLEAR_CONFIRMATION);
 338                         x25_disconnect(sk, 0, skb->data[3], skb->data[4]);
 339                         break;
 340
 341                 default:
 342                         break;
 343         }
 344
 345         return 0;
 346 }
 347
 348 /* Higher level upcall for a LAPB frame */
 349 int x25_process_rx_frame(struct sock *sk, struct sk_buff *skb)
 350 {
 351         struct x25_sock *x25 = x25_sk(sk);
 352         int queued = 0, frametype, ns, nr, q, d, m;
 353
 354         if (x25->state == X25_STATE_0)
 355                 return 0;
 356
 357         frametype = x25_decode(sk, skb, &ns, &nr, &q, &d, &m);
 358
 359         switch (x25->state) {
 360         case X25_STATE_1:
 361                 queued = x25_state1_machine(sk, skb, frametype);
 362                 break;
 363         case X25_STATE_2:
 364                 queued = x25_state2_machine(sk, skb, frametype);
 365                 break;
 366         case X25_STATE_3:
 367                 queued = x25_state3_machine(sk, skb, frametype, ns, nr, q, d, m);
 368                 break;
 369         case X25_STATE_4:
 370                 queued = x25_state4_machine(sk, skb, frametype);
 371                 break;
 372         }
 373
 374         x25_kick(sk);
 375
 376         return queued;
 377 }
 378
 379 int x25_backlog_rcv(struct sock *sk, struct sk_buff *skb)
 380 {
 381         int queued = x25_process_rx_frame(sk, skb);
 382
 383         if (!queued)
 384                 kfree_skb(skb);
 385
 386         return 0;
 387 }