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