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                 skbn->h.raw = skbn->data;
  57
  58                 skbo = skb_dequeue(&x25->fragment_queue);
  59                 memcpy(skb_put(skbn, skbo->len), skbo->data, skbo->len);
  60                 kfree_skb(skbo);
  61
  62                 while ((skbo =
  63                         skb_dequeue(&x25->fragment_queue)) != NULL) {
  64                         skb_pull(skbo, (x25->neighbour->extended) ?
  65                                         X25_EXT_MIN_LEN : X25_STD_MIN_LEN);
  66                         memcpy(skb_put(skbn, skbo->len), skbo->data, skbo->len);
  67                         kfree_skb(skbo);
  68                 }
  69
  70                 x25->fraglen = 0;
  71         }
  72
  73         skb_set_owner_r(skbn, sk);
  74         skb_queue_tail(&sk->sk_receive_queue, skbn);
  75         if (!sock_flag(sk, SOCK_DEAD))
  76                 sk->sk_data_ready(sk, skbn->len);
  77
  78         return 0;
  79 }
  80
  81 /*
  82  * State machine for state 1, Awaiting Call Accepted State.
  83  * The handling of the timer(s) is in file x25_timer.c.
  84  * Handling of state 0 and connection release is in af_x25.c.
  85  */
  86 static int x25_state1_machine(struct sock *sk, struct sk_buff *skb, int frametype)
  87 {
  88         struct x25_address source_addr, dest_addr;
  89
  90         switch (frametype) {
  91                 case X25_CALL_ACCEPTED: {
  92                         struct x25_sock *x25 = x25_sk(sk);
  93
  94                         x25_stop_timer(sk);
  95                         x25->condition = 0x00;
  96                         x25->vs        = 0;
  97                         x25->va        = 0;
  98                         x25->vr        = 0;
  99                         x25->vl        = 0;
 100                         x25->state     = X25_STATE_3;
 101                         sk->sk_state   = TCP_ESTABLISHED;
 102                         /*
 103                          *      Parse the data in the frame.
 104                          */
 105                         skb_pull(skb, X25_STD_MIN_LEN);
 106                         skb_pull(skb, x25_addr_ntoa(skb->data, &source_addr, &dest_addr));
 107                         skb_pull(skb,
 108                                  x25_parse_facilities(skb, &x25->facilities,
 109                                                 &x25->dte_facilities,
 110                                                 &x25->vc_facil_mask));
 111                         /*
 112                          *      Copy any Call User Data.
 113                          */
 114                         if (skb->len >= 0) {
 115                                 memcpy(x25->calluserdata.cuddata, skb->data,
 116                                        skb->len);
 117                                 x25->calluserdata.cudlength = skb->len;
 118                         }
 119                         if (!sock_flag(sk, SOCK_DEAD))
 120                                 sk->sk_state_change(sk);
 121                         break;
 122                 }
 123                 case X25_CLEAR_REQUEST:
 124                         x25_write_internal(sk, X25_CLEAR_CONFIRMATION);
 125                         x25_disconnect(sk, ECONNREFUSED, skb->data[3], skb->data[4]);
 126                         break;
 127
 128                 default:
 129                         break;
 130         }
 131
 132         return 0;
 133 }
 134
 135 /*
 136  * State machine for state 2, Awaiting Clear Confirmation State.
 137  * The handling of the timer(s) is in file x25_timer.c
 138  * Handling of state 0 and connection release is in af_x25.c.
 139  */
 140 static int x25_state2_machine(struct sock *sk, struct sk_buff *skb, int frametype)
 141 {
 142         switch (frametype) {
 143
 144                 case X25_CLEAR_REQUEST:
 145                         x25_write_internal(sk, X25_CLEAR_CONFIRMATION);
 146                         x25_disconnect(sk, 0, skb->data[3], skb->data[4]);
 147                         break;
 148
 149                 case X25_CLEAR_CONFIRMATION:
 150                         x25_disconnect(sk, 0, 0, 0);
 151                         break;
 152
 153                 default:
 154                         break;
 155         }
 156
 157         return 0;
 158 }
 159
 160 /*
 161  * State machine for state 3, Connected 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_state3_machine(struct sock *sk, struct sk_buff *skb, int frametype, int ns, int nr, int q, int d, int m)
 166 {
 167         int queued = 0;
 168         int modulus;
 169         struct x25_sock *x25 = x25_sk(sk);
 170
 171         modulus = (x25->neighbour->extended) ? X25_EMODULUS : X25_SMODULUS;
 172
 173         switch (frametype) {
 174
 175                 case X25_RESET_REQUEST:
 176                         x25_write_internal(sk, X25_RESET_CONFIRMATION);
 177                         x25_stop_timer(sk);
 178                         x25->condition = 0x00;
 179                         x25->vs        = 0;
 180                         x25->vr        = 0;
 181                         x25->va        = 0;
 182                         x25->vl        = 0;
 183                         x25_requeue_frames(sk);
 184                         break;
 185
 186                 case X25_CLEAR_REQUEST:
 187                         x25_write_internal(sk, X25_CLEAR_CONFIRMATION);
 188                         x25_disconnect(sk, 0, skb->data[3], skb->data[4]);
 189                         break;
 190
 191                 case X25_RR:
 192                 case X25_RNR:
 193                         if (!x25_validate_nr(sk, nr)) {
 194                                 x25_clear_queues(sk);
 195                                 x25_write_internal(sk, X25_RESET_REQUEST);
 196                                 x25_start_t22timer(sk);
 197                                 x25->condition = 0x00;
 198                                 x25->vs        = 0;
 199                                 x25->vr        = 0;
 200                                 x25->va        = 0;
 201                                 x25->vl        = 0;
 202                                 x25->state     = X25_STATE_4;
 203                         } else {
 204                                 x25_frames_acked(sk, nr);
 205                                 if (frametype == X25_RNR) {
 206                                         x25->condition |= X25_COND_PEER_RX_BUSY;
 207                                 } else {
 208                                         x25->condition &= ~X25_COND_PEER_RX_BUSY;
 209                                 }
 210                         }
 211                         break;
 212
 213                 case X25_DATA:  /* XXX */
 214                         x25->condition &= ~X25_COND_PEER_RX_BUSY;
 215                         if ((ns != x25->vr) || !x25_validate_nr(sk, nr)) {
 216                                 x25_clear_queues(sk);
 217                                 x25_write_internal(sk, X25_RESET_REQUEST);
 218                                 x25_start_t22timer(sk);
 219                                 x25->condition = 0x00;
 220                                 x25->vs        = 0;
 221                                 x25->vr        = 0;
 222                                 x25->va        = 0;
 223                                 x25->vl        = 0;
 224                                 x25->state     = X25_STATE_4;
 225                                 break;
 226                         }
 227                         x25_frames_acked(sk, nr);
 228                         if (ns == x25->vr) {
 229                                 if (x25_queue_rx_frame(sk, skb, m) == 0) {
 230                                         x25->vr = (x25->vr + 1) % modulus;
 231                                         queued = 1;
 232                                 } else {
 233                                         /* Should never happen */
 234                                         x25_clear_queues(sk);
 235                                         x25_write_internal(sk, X25_RESET_REQUEST);
 236                                         x25_start_t22timer(sk);
 237                                         x25->condition = 0x00;
 238                                         x25->vs        = 0;
 239                                         x25->vr        = 0;
 240                                         x25->va        = 0;
 241                                         x25->vl        = 0;
 242                                         x25->state     = X25_STATE_4;
 243                                         break;
 244                                 }
 245                                 if (atomic_read(&sk->sk_rmem_alloc) >
 246                                     (sk->sk_rcvbuf / 2))
 247                                         x25->condition |= X25_COND_OWN_RX_BUSY;
 248                         }
 249                         /*
 250                          *      If the window is full Ack it immediately, else
 251                          *      start the holdback timer.
 252                          */
 253                         if (((x25->vl + x25->facilities.winsize_in) % modulus) == x25->vr) {
 254                                 x25->condition &= ~X25_COND_ACK_PENDING;
 255                                 x25_stop_timer(sk);
 256                                 x25_enquiry_response(sk);
 257                         } else {
 258                                 x25->condition |= X25_COND_ACK_PENDING;
 259                                 x25_start_t2timer(sk);
 260                         }
 261                         break;
 262
 263                 case X25_INTERRUPT_CONFIRMATION:
 264                         x25->intflag = 0;
 265                         break;
 266
 267                 case X25_INTERRUPT:
 268                         if (sock_flag(sk, SOCK_URGINLINE))
 269                                 queued = !sock_queue_rcv_skb(sk, skb);
 270                         else {
 271                                 skb_set_owner_r(skb, sk);
 272                                 skb_queue_tail(&x25->interrupt_in_queue, skb);
 273                                 queued = 1;
 274                         }
 275                         sk_send_sigurg(sk);
 276                         x25_write_internal(sk, X25_INTERRUPT_CONFIRMATION);
 277                         break;
 278
 279                 default:
 280                         printk(KERN_WARNING "x25: unknown %02X in state 3\n", frametype);
 281                         break;
 282         }
 283
 284         return queued;
 285 }
 286
 287 /*
 288  * State machine for state 4, Awaiting Reset Confirmation State.
 289  * The handling of the timer(s) is in file x25_timer.c
 290  * Handling of state 0 and connection release is in af_x25.c.
 291  */
 292 static int x25_state4_machine(struct sock *sk, struct sk_buff *skb, int frametype)
 293 {
 294         switch (frametype) {
 295
 296                 case X25_RESET_REQUEST:
 297                         x25_write_internal(sk, X25_RESET_CONFIRMATION);
 298                 case X25_RESET_CONFIRMATION: {
 299                         struct x25_sock *x25 = x25_sk(sk);
 300
 301                         x25_stop_timer(sk);
 302                         x25->condition = 0x00;
 303                         x25->va        = 0;
 304                         x25->vr        = 0;
 305                         x25->vs        = 0;
 306                         x25->vl        = 0;
 307                         x25->state     = X25_STATE_3;
 308                         x25_requeue_frames(sk);
 309                         break;
 310                 }
 311                 case X25_CLEAR_REQUEST:
 312                         x25_write_internal(sk, X25_CLEAR_CONFIRMATION);
 313                         x25_disconnect(sk, 0, skb->data[3], skb->data[4]);
 314                         break;
 315
 316                 default:
 317                         break;
 318         }
 319
 320         return 0;
 321 }
 322
 323 /* Higher level upcall for a LAPB frame */
 324 int x25_process_rx_frame(struct sock *sk, struct sk_buff *skb)
 325 {
 326         struct x25_sock *x25 = x25_sk(sk);
 327         int queued = 0, frametype, ns, nr, q, d, m;
 328
 329         if (x25->state == X25_STATE_0)
 330                 return 0;
 331
 332         frametype = x25_decode(sk, skb, &ns, &nr, &q, &d, &m);
 333
 334         switch (x25->state) {
 335                 case X25_STATE_1:
 336                         queued = x25_state1_machine(sk, skb, frametype);
 337                         break;
 338                 case X25_STATE_2:
 339                         queued = x25_state2_machine(sk, skb, frametype);
 340                         break;
 341                 case X25_STATE_3:
 342                         queued = x25_state3_machine(sk, skb, frametype, ns, nr, q, d, m);
 343                         break;
 344                 case X25_STATE_4:
 345                         queued = x25_state4_machine(sk, skb, frametype);
 346                         break;
 347         }
 348
 349         x25_kick(sk);
 350
 351         return queued;
 352 }
 353
 354 int x25_backlog_rcv(struct sock *sk, struct sk_buff *skb)
 355 {
 356         int queued = x25_process_rx_frame(sk, skb);
 357
 358         if (!queued)
 359                 kfree_skb(skb);
 360
 361         return 0;
 362 }