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