linux/net/x25/x25_in.c
<<
>>
Prefs
   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#define pr_fmt(fmt) "X25: " fmt
  27
  28#include <linux/slab.h>
  29#include <linux/errno.h>
  30#include <linux/kernel.h>
  31#include <linux/string.h>
  32#include <linux/skbuff.h>
  33#include <net/sock.h>
  34#include <net/tcp_states.h>
  35#include <net/x25.h>
  36
  37static int x25_queue_rx_frame(struct sock *sk, struct sk_buff *skb, int more)
  38{
  39        struct sk_buff *skbo, *skbn = skb;
  40        struct x25_sock *x25 = x25_sk(sk);
  41
  42        if (more) {
  43                x25->fraglen += skb->len;
  44                skb_queue_tail(&x25->fragment_queue, skb);
  45                skb_set_owner_r(skb, sk);
  46                return 0;
  47        }
  48
  49        if (!more && x25->fraglen > 0) {        /* End of fragment */
  50                int len = x25->fraglen + skb->len;
  51
  52                if ((skbn = alloc_skb(len, GFP_ATOMIC)) == NULL){
  53                        kfree_skb(skb);
  54                        return 1;
  55                }
  56
  57                skb_queue_tail(&x25->fragment_queue, skb);
  58
  59                skb_reset_transport_header(skbn);
  60
  61                skbo = skb_dequeue(&x25->fragment_queue);
  62                skb_copy_from_linear_data(skbo, skb_put(skbn, skbo->len),
  63                                          skbo->len);
  64                kfree_skb(skbo);
  65
  66                while ((skbo =
  67                        skb_dequeue(&x25->fragment_queue)) != NULL) {
  68                        skb_pull(skbo, (x25->neighbour->extended) ?
  69                                        X25_EXT_MIN_LEN : X25_STD_MIN_LEN);
  70                        skb_copy_from_linear_data(skbo,
  71                                                  skb_put(skbn, skbo->len),
  72                                                  skbo->len);
  73                        kfree_skb(skbo);
  74                }
  75
  76                x25->fraglen = 0;
  77        }
  78
  79        skb_set_owner_r(skbn, sk);
  80        skb_queue_tail(&sk->sk_receive_queue, skbn);
  81        if (!sock_flag(sk, SOCK_DEAD))
  82                sk->sk_data_ready(sk);
  83
  84        return 0;
  85}
  86
  87/*
  88 * State machine for state 1, Awaiting Call Accepted State.
  89 * The handling of the timer(s) is in file x25_timer.c.
  90 * Handling of state 0 and connection release is in af_x25.c.
  91 */
  92static int x25_state1_machine(struct sock *sk, struct sk_buff *skb, int frametype)
  93{
  94        struct x25_address source_addr, dest_addr;
  95        int len;
  96        struct x25_sock *x25 = x25_sk(sk);
  97
  98        switch (frametype) {
  99        case X25_CALL_ACCEPTED: {
 100
 101                x25_stop_timer(sk);
 102                x25->condition = 0x00;
 103                x25->vs        = 0;
 104                x25->va        = 0;
 105                x25->vr        = 0;
 106                x25->vl        = 0;
 107                x25->state     = X25_STATE_3;
 108                sk->sk_state   = TCP_ESTABLISHED;
 109                /*
 110                 *      Parse the data in the frame.
 111                 */
 112                if (!pskb_may_pull(skb, X25_STD_MIN_LEN))
 113                        goto out_clear;
 114                skb_pull(skb, X25_STD_MIN_LEN);
 115
 116                len = x25_parse_address_block(skb, &source_addr,
 117                                              &dest_addr);
 118                if (len > 0)
 119                        skb_pull(skb, len);
 120                else if (len < 0)
 121                        goto out_clear;
 122
 123                len = x25_parse_facilities(skb, &x25->facilities,
 124                                           &x25->dte_facilities,
 125                                           &x25->vc_facil_mask);
 126                if (len > 0)
 127                        skb_pull(skb, len);
 128                else if (len < 0)
 129                        goto out_clear;
 130                /*
 131                 *      Copy any Call User Data.
 132                 */
 133                if (skb->len > 0) {
 134                        if (skb->len > X25_MAX_CUD_LEN)
 135                                goto out_clear;
 136
 137                        skb_copy_bits(skb, 0, x25->calluserdata.cuddata,
 138                                skb->len);
 139                        x25->calluserdata.cudlength = skb->len;
 140                }
 141                if (!sock_flag(sk, SOCK_DEAD))
 142                        sk->sk_state_change(sk);
 143                break;
 144        }
 145        case X25_CLEAR_REQUEST:
 146                if (!pskb_may_pull(skb, X25_STD_MIN_LEN + 2))
 147                        goto out_clear;
 148
 149                x25_write_internal(sk, X25_CLEAR_CONFIRMATION);
 150                x25_disconnect(sk, ECONNREFUSED, skb->data[3], skb->data[4]);
 151                break;
 152
 153        default:
 154                break;
 155        }
 156
 157        return 0;
 158
 159out_clear:
 160        x25_write_internal(sk, X25_CLEAR_REQUEST);
 161        x25->state = X25_STATE_2;
 162        x25_start_t23timer(sk);
 163        return 0;
 164}
 165
 166/*
 167 * State machine for state 2, Awaiting Clear Confirmation State.
 168 * The handling of the timer(s) is in file x25_timer.c
 169 * Handling of state 0 and connection release is in af_x25.c.
 170 */
 171static int x25_state2_machine(struct sock *sk, struct sk_buff *skb, int frametype)
 172{
 173        switch (frametype) {
 174
 175                case X25_CLEAR_REQUEST:
 176                        if (!pskb_may_pull(skb, X25_STD_MIN_LEN + 2))
 177                                goto out_clear;
 178
 179                        x25_write_internal(sk, X25_CLEAR_CONFIRMATION);
 180                        x25_disconnect(sk, 0, skb->data[3], skb->data[4]);
 181                        break;
 182
 183                case X25_CLEAR_CONFIRMATION:
 184                        x25_disconnect(sk, 0, 0, 0);
 185                        break;
 186
 187                default:
 188                        break;
 189        }
 190
 191        return 0;
 192
 193out_clear:
 194        x25_write_internal(sk, X25_CLEAR_REQUEST);
 195        x25_start_t23timer(sk);
 196        return 0;
 197}
 198
 199/*
 200 * State machine for state 3, Connected State.
 201 * The handling of the timer(s) is in file x25_timer.c
 202 * Handling of state 0 and connection release is in af_x25.c.
 203 */
 204static int x25_state3_machine(struct sock *sk, struct sk_buff *skb, int frametype, int ns, int nr, int q, int d, int m)
 205{
 206        int queued = 0;
 207        int modulus;
 208        struct x25_sock *x25 = x25_sk(sk);
 209
 210        modulus = (x25->neighbour->extended) ? X25_EMODULUS : X25_SMODULUS;
 211
 212        switch (frametype) {
 213
 214                case X25_RESET_REQUEST:
 215                        x25_write_internal(sk, X25_RESET_CONFIRMATION);
 216                        x25_stop_timer(sk);
 217                        x25->condition = 0x00;
 218                        x25->vs        = 0;
 219                        x25->vr        = 0;
 220                        x25->va        = 0;
 221                        x25->vl        = 0;
 222                        x25_requeue_frames(sk);
 223                        break;
 224
 225                case X25_CLEAR_REQUEST:
 226                        if (!pskb_may_pull(skb, X25_STD_MIN_LEN + 2))
 227                                goto out_clear;
 228
 229                        x25_write_internal(sk, X25_CLEAR_CONFIRMATION);
 230                        x25_disconnect(sk, 0, skb->data[3], skb->data[4]);
 231                        break;
 232
 233                case X25_RR:
 234                case X25_RNR:
 235                        if (!x25_validate_nr(sk, nr)) {
 236                                x25_clear_queues(sk);
 237                                x25_write_internal(sk, X25_RESET_REQUEST);
 238                                x25_start_t22timer(sk);
 239                                x25->condition = 0x00;
 240                                x25->vs        = 0;
 241                                x25->vr        = 0;
 242                                x25->va        = 0;
 243                                x25->vl        = 0;
 244                                x25->state     = X25_STATE_4;
 245                        } else {
 246                                x25_frames_acked(sk, nr);
 247                                if (frametype == X25_RNR) {
 248                                        x25->condition |= X25_COND_PEER_RX_BUSY;
 249                                } else {
 250                                        x25->condition &= ~X25_COND_PEER_RX_BUSY;
 251                                }
 252                        }
 253                        break;
 254
 255                case X25_DATA:  /* XXX */
 256                        x25->condition &= ~X25_COND_PEER_RX_BUSY;
 257                        if ((ns != x25->vr) || !x25_validate_nr(sk, nr)) {
 258                                x25_clear_queues(sk);
 259                                x25_write_internal(sk, X25_RESET_REQUEST);
 260                                x25_start_t22timer(sk);
 261                                x25->condition = 0x00;
 262                                x25->vs        = 0;
 263                                x25->vr        = 0;
 264                                x25->va        = 0;
 265                                x25->vl        = 0;
 266                                x25->state     = X25_STATE_4;
 267                                break;
 268                        }
 269                        x25_frames_acked(sk, nr);
 270                        if (ns == x25->vr) {
 271                                if (x25_queue_rx_frame(sk, skb, m) == 0) {
 272                                        x25->vr = (x25->vr + 1) % modulus;
 273                                        queued = 1;
 274                                } else {
 275                                        /* Should never happen */
 276                                        x25_clear_queues(sk);
 277                                        x25_write_internal(sk, X25_RESET_REQUEST);
 278                                        x25_start_t22timer(sk);
 279                                        x25->condition = 0x00;
 280                                        x25->vs        = 0;
 281                                        x25->vr        = 0;
 282                                        x25->va        = 0;
 283                                        x25->vl        = 0;
 284                                        x25->state     = X25_STATE_4;
 285                                        break;
 286                                }
 287                                if (atomic_read(&sk->sk_rmem_alloc) >
 288                                    (sk->sk_rcvbuf >> 1))
 289                                        x25->condition |= X25_COND_OWN_RX_BUSY;
 290                        }
 291                        /*
 292                         *      If the window is full Ack it immediately, else
 293                         *      start the holdback timer.
 294                         */
 295                        if (((x25->vl + x25->facilities.winsize_in) % modulus) == x25->vr) {
 296                                x25->condition &= ~X25_COND_ACK_PENDING;
 297                                x25_stop_timer(sk);
 298                                x25_enquiry_response(sk);
 299                        } else {
 300                                x25->condition |= X25_COND_ACK_PENDING;
 301                                x25_start_t2timer(sk);
 302                        }
 303                        break;
 304
 305                case X25_INTERRUPT_CONFIRMATION:
 306                        clear_bit(X25_INTERRUPT_FLAG, &x25->flags);
 307                        break;
 308
 309                case X25_INTERRUPT:
 310                        if (sock_flag(sk, SOCK_URGINLINE))
 311                                queued = !sock_queue_rcv_skb(sk, skb);
 312                        else {
 313                                skb_set_owner_r(skb, sk);
 314                                skb_queue_tail(&x25->interrupt_in_queue, skb);
 315                                queued = 1;
 316                        }
 317                        sk_send_sigurg(sk);
 318                        x25_write_internal(sk, X25_INTERRUPT_CONFIRMATION);
 319                        break;
 320
 321                default:
 322                        pr_warn("unknown %02X in state 3\n", frametype);
 323                        break;
 324        }
 325
 326        return queued;
 327
 328out_clear:
 329        x25_write_internal(sk, X25_CLEAR_REQUEST);
 330        x25->state = X25_STATE_2;
 331        x25_start_t23timer(sk);
 332        return 0;
 333}
 334
 335/*
 336 * State machine for state 4, Awaiting Reset Confirmation State.
 337 * The handling of the timer(s) is in file x25_timer.c
 338 * Handling of state 0 and connection release is in af_x25.c.
 339 */
 340static int x25_state4_machine(struct sock *sk, struct sk_buff *skb, int frametype)
 341{
 342        struct x25_sock *x25 = x25_sk(sk);
 343
 344        switch (frametype) {
 345
 346                case X25_RESET_REQUEST:
 347                        x25_write_internal(sk, X25_RESET_CONFIRMATION);
 348                case X25_RESET_CONFIRMATION: {
 349                        x25_stop_timer(sk);
 350                        x25->condition = 0x00;
 351                        x25->va        = 0;
 352                        x25->vr        = 0;
 353                        x25->vs        = 0;
 354                        x25->vl        = 0;
 355                        x25->state     = X25_STATE_3;
 356                        x25_requeue_frames(sk);
 357                        break;
 358                }
 359                case X25_CLEAR_REQUEST:
 360                        if (!pskb_may_pull(skb, X25_STD_MIN_LEN + 2))
 361                                goto out_clear;
 362
 363                        x25_write_internal(sk, X25_CLEAR_CONFIRMATION);
 364                        x25_disconnect(sk, 0, skb->data[3], skb->data[4]);
 365                        break;
 366
 367                default:
 368                        break;
 369        }
 370
 371        return 0;
 372
 373out_clear:
 374        x25_write_internal(sk, X25_CLEAR_REQUEST);
 375        x25->state = X25_STATE_2;
 376        x25_start_t23timer(sk);
 377        return 0;
 378}
 379
 380/* Higher level upcall for a LAPB frame */
 381int x25_process_rx_frame(struct sock *sk, struct sk_buff *skb)
 382{
 383        struct x25_sock *x25 = x25_sk(sk);
 384        int queued = 0, frametype, ns, nr, q, d, m;
 385
 386        if (x25->state == X25_STATE_0)
 387                return 0;
 388
 389        frametype = x25_decode(sk, skb, &ns, &nr, &q, &d, &m);
 390
 391        switch (x25->state) {
 392        case X25_STATE_1:
 393                queued = x25_state1_machine(sk, skb, frametype);
 394                break;
 395        case X25_STATE_2:
 396                queued = x25_state2_machine(sk, skb, frametype);
 397                break;
 398        case X25_STATE_3:
 399                queued = x25_state3_machine(sk, skb, frametype, ns, nr, q, d, m);
 400                break;
 401        case X25_STATE_4:
 402                queued = x25_state4_machine(sk, skb, frametype);
 403                break;
 404        }
 405
 406        x25_kick(sk);
 407
 408        return queued;
 409}
 410
 411int x25_backlog_rcv(struct sock *sk, struct sk_buff *skb)
 412{
 413        int queued = x25_process_rx_frame(sk, skb);
 414
 415        if (!queued)
 416                kfree_skb(skb);
 417
 418        return 0;
 419}
 420