linux/net/x25/x25_in.c
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   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
  35static 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 */
  90static 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                if (!pskb_may_pull(skb, X25_STD_MIN_LEN))
 111                        goto out_clear;
 112                skb_pull(skb, X25_STD_MIN_LEN);
 113
 114                len = x25_parse_address_block(skb, &source_addr,
 115                                              &dest_addr);
 116                if (len > 0)
 117                        skb_pull(skb, len);
 118                else if (len < 0)
 119                        goto out_clear;
 120
 121                len = x25_parse_facilities(skb, &x25->facilities,
 122                                           &x25->dte_facilities,
 123                                           &x25->vc_facil_mask);
 124                if (len > 0)
 125                        skb_pull(skb, len);
 126                else if (len < 0)
 127                        goto out_clear;
 128                /*
 129                 *      Copy any Call User Data.
 130                 */
 131                if (skb->len > 0) {
 132                        if (skb->len > X25_MAX_CUD_LEN)
 133                                goto out_clear;
 134
 135                        skb_copy_bits(skb, 0, x25->calluserdata.cuddata,
 136                                skb->len);
 137                        x25->calluserdata.cudlength = skb->len;
 138                }
 139                if (!sock_flag(sk, SOCK_DEAD))
 140                        sk->sk_state_change(sk);
 141                break;
 142        }
 143        case X25_CLEAR_REQUEST:
 144                if (!pskb_may_pull(skb, X25_STD_MIN_LEN + 2))
 145                        goto out_clear;
 146
 147                x25_write_internal(sk, X25_CLEAR_CONFIRMATION);
 148                x25_disconnect(sk, ECONNREFUSED, skb->data[3], skb->data[4]);
 149                break;
 150
 151        default:
 152                break;
 153        }
 154
 155        return 0;
 156
 157out_clear:
 158        x25_write_internal(sk, X25_CLEAR_REQUEST);
 159        x25->state = X25_STATE_2;
 160        x25_start_t23timer(sk);
 161        return 0;
 162}
 163
 164/*
 165 * State machine for state 2, Awaiting Clear Confirmation State.
 166 * The handling of the timer(s) is in file x25_timer.c
 167 * Handling of state 0 and connection release is in af_x25.c.
 168 */
 169static int x25_state2_machine(struct sock *sk, struct sk_buff *skb, int frametype)
 170{
 171        switch (frametype) {
 172
 173                case X25_CLEAR_REQUEST:
 174                        if (!pskb_may_pull(skb, X25_STD_MIN_LEN + 2))
 175                                goto out_clear;
 176
 177                        x25_write_internal(sk, X25_CLEAR_CONFIRMATION);
 178                        x25_disconnect(sk, 0, skb->data[3], skb->data[4]);
 179                        break;
 180
 181                case X25_CLEAR_CONFIRMATION:
 182                        x25_disconnect(sk, 0, 0, 0);
 183                        break;
 184
 185                default:
 186                        break;
 187        }
 188
 189        return 0;
 190
 191out_clear:
 192        x25_write_internal(sk, X25_CLEAR_REQUEST);
 193        x25_start_t23timer(sk);
 194        return 0;
 195}
 196
 197/*
 198 * State machine for state 3, Connected State.
 199 * The handling of the timer(s) is in file x25_timer.c
 200 * Handling of state 0 and connection release is in af_x25.c.
 201 */
 202static int x25_state3_machine(struct sock *sk, struct sk_buff *skb, int frametype, int ns, int nr, int q, int d, int m)
 203{
 204        int queued = 0;
 205        int modulus;
 206        struct x25_sock *x25 = x25_sk(sk);
 207
 208        modulus = (x25->neighbour->extended) ? X25_EMODULUS : X25_SMODULUS;
 209
 210        switch (frametype) {
 211
 212                case X25_RESET_REQUEST:
 213                        x25_write_internal(sk, X25_RESET_CONFIRMATION);
 214                        x25_stop_timer(sk);
 215                        x25->condition = 0x00;
 216                        x25->vs        = 0;
 217                        x25->vr        = 0;
 218                        x25->va        = 0;
 219                        x25->vl        = 0;
 220                        x25_requeue_frames(sk);
 221                        break;
 222
 223                case X25_CLEAR_REQUEST:
 224                        if (!pskb_may_pull(skb, X25_STD_MIN_LEN + 2))
 225                                goto out_clear;
 226
 227                        x25_write_internal(sk, X25_CLEAR_CONFIRMATION);
 228                        x25_disconnect(sk, 0, skb->data[3], skb->data[4]);
 229                        break;
 230
 231                case X25_RR:
 232                case X25_RNR:
 233                        if (!x25_validate_nr(sk, nr)) {
 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                        } else {
 244                                x25_frames_acked(sk, nr);
 245                                if (frametype == X25_RNR) {
 246                                        x25->condition |= X25_COND_PEER_RX_BUSY;
 247                                } else {
 248                                        x25->condition &= ~X25_COND_PEER_RX_BUSY;
 249                                }
 250                        }
 251                        break;
 252
 253                case X25_DATA:  /* XXX */
 254                        x25->condition &= ~X25_COND_PEER_RX_BUSY;
 255                        if ((ns != x25->vr) || !x25_validate_nr(sk, nr)) {
 256                                x25_clear_queues(sk);
 257                                x25_write_internal(sk, X25_RESET_REQUEST);
 258                                x25_start_t22timer(sk);
 259                                x25->condition = 0x00;
 260                                x25->vs        = 0;
 261                                x25->vr        = 0;
 262                                x25->va        = 0;
 263                                x25->vl        = 0;
 264                                x25->state     = X25_STATE_4;
 265                                break;
 266                        }
 267                        x25_frames_acked(sk, nr);
 268                        if (ns == x25->vr) {
 269                                if (x25_queue_rx_frame(sk, skb, m) == 0) {
 270                                        x25->vr = (x25->vr + 1) % modulus;
 271                                        queued = 1;
 272                                } else {
 273                                        /* Should never happen */
 274                                        x25_clear_queues(sk);
 275                                        x25_write_internal(sk, X25_RESET_REQUEST);
 276                                        x25_start_t22timer(sk);
 277                                        x25->condition = 0x00;
 278                                        x25->vs        = 0;
 279                                        x25->vr        = 0;
 280                                        x25->va        = 0;
 281                                        x25->vl        = 0;
 282                                        x25->state     = X25_STATE_4;
 283                                        break;
 284                                }
 285                                if (atomic_read(&sk->sk_rmem_alloc) >
 286                                    (sk->sk_rcvbuf >> 1))
 287                                        x25->condition |= X25_COND_OWN_RX_BUSY;
 288                        }
 289                        /*
 290                         *      If the window is full Ack it immediately, else
 291                         *      start the holdback timer.
 292                         */
 293                        if (((x25->vl + x25->facilities.winsize_in) % modulus) == x25->vr) {
 294                                x25->condition &= ~X25_COND_ACK_PENDING;
 295                                x25_stop_timer(sk);
 296                                x25_enquiry_response(sk);
 297                        } else {
 298                                x25->condition |= X25_COND_ACK_PENDING;
 299                                x25_start_t2timer(sk);
 300                        }
 301                        break;
 302
 303                case X25_INTERRUPT_CONFIRMATION:
 304                        clear_bit(X25_INTERRUPT_FLAG, &x25->flags);
 305                        break;
 306
 307                case X25_INTERRUPT:
 308                        if (sock_flag(sk, SOCK_URGINLINE))
 309                                queued = !sock_queue_rcv_skb(sk, skb);
 310                        else {
 311                                skb_set_owner_r(skb, sk);
 312                                skb_queue_tail(&x25->interrupt_in_queue, skb);
 313                                queued = 1;
 314                        }
 315                        sk_send_sigurg(sk);
 316                        x25_write_internal(sk, X25_INTERRUPT_CONFIRMATION);
 317                        break;
 318
 319                default:
 320                        printk(KERN_WARNING "x25: unknown %02X in state 3\n", frametype);
 321                        break;
 322        }
 323
 324        return queued;
 325
 326out_clear:
 327        x25_write_internal(sk, X25_CLEAR_REQUEST);
 328        x25->state = X25_STATE_2;
 329        x25_start_t23timer(sk);
 330        return 0;
 331}
 332
 333/*
 334 * State machine for state 4, Awaiting Reset Confirmation State.
 335 * The handling of the timer(s) is in file x25_timer.c
 336 * Handling of state 0 and connection release is in af_x25.c.
 337 */
 338static int x25_state4_machine(struct sock *sk, struct sk_buff *skb, int frametype)
 339{
 340        struct x25_sock *x25 = x25_sk(sk);
 341
 342        switch (frametype) {
 343
 344                case X25_RESET_REQUEST:
 345                        x25_write_internal(sk, X25_RESET_CONFIRMATION);
 346                case X25_RESET_CONFIRMATION: {
 347                        x25_stop_timer(sk);
 348                        x25->condition = 0x00;
 349                        x25->va        = 0;
 350                        x25->vr        = 0;
 351                        x25->vs        = 0;
 352                        x25->vl        = 0;
 353                        x25->state     = X25_STATE_3;
 354                        x25_requeue_frames(sk);
 355                        break;
 356                }
 357                case X25_CLEAR_REQUEST:
 358                        if (!pskb_may_pull(skb, X25_STD_MIN_LEN + 2))
 359                                goto out_clear;
 360
 361                        x25_write_internal(sk, X25_CLEAR_CONFIRMATION);
 362                        x25_disconnect(sk, 0, skb->data[3], skb->data[4]);
 363                        break;
 364
 365                default:
 366                        break;
 367        }
 368
 369        return 0;
 370
 371out_clear:
 372        x25_write_internal(sk, X25_CLEAR_REQUEST);
 373        x25->state = X25_STATE_2;
 374        x25_start_t23timer(sk);
 375        return 0;
 376}
 377
 378/* Higher level upcall for a LAPB frame */
 379int x25_process_rx_frame(struct sock *sk, struct sk_buff *skb)
 380{
 381        struct x25_sock *x25 = x25_sk(sk);
 382        int queued = 0, frametype, ns, nr, q, d, m;
 383
 384        if (x25->state == X25_STATE_0)
 385                return 0;
 386
 387        frametype = x25_decode(sk, skb, &ns, &nr, &q, &d, &m);
 388
 389        switch (x25->state) {
 390        case X25_STATE_1:
 391                queued = x25_state1_machine(sk, skb, frametype);
 392                break;
 393        case X25_STATE_2:
 394                queued = x25_state2_machine(sk, skb, frametype);
 395                break;
 396        case X25_STATE_3:
 397                queued = x25_state3_machine(sk, skb, frametype, ns, nr, q, d, m);
 398                break;
 399        case X25_STATE_4:
 400                queued = x25_state4_machine(sk, skb, frametype);
 401                break;
 402        }
 403
 404        x25_kick(sk);
 405
 406        return queued;
 407}
 408
 409int x25_backlog_rcv(struct sock *sk, struct sk_buff *skb)
 410{
 411        int queued = x25_process_rx_frame(sk, skb);
 412
 413        if (!queued)
 414                kfree_skb(skb);
 415
 416        return 0;
 417}
 418
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