LXR linux/net/x25/x25

   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 processing.
  19 *      mar/20/00       Daniela Squassoni Disabling/enabling of facilities
  20 *                                        negotiation.
  21 *      jun/24/01       Arnaldo C. Melo   use skb_queue_purge, cleanups
  22 *      apr/04/15       Shaun Pereira           Fast select with no
  23 *                                              restriction on response.
  24 */
  25
  26#define pr_fmt(fmt) "X25: " fmt
  27
  28#include <linux/slab.h>
  29#include <linux/kernel.h>
  30#include <linux/string.h>
  31#include <linux/skbuff.h>
  32#include <net/sock.h>
  33#include <net/tcp_states.h>
  34#include <net/x25.h>
  35
  36/*
  37 *      This routine purges all of the queues of frames.
  38 */
  39void x25_clear_queues(struct sock *sk)
  40{
  41        struct x25_sock *x25 = x25_sk(sk);
  42
  43        skb_queue_purge(&sk->sk_write_queue);
  44        skb_queue_purge(&x25->ack_queue);
  45        skb_queue_purge(&x25->interrupt_in_queue);
  46        skb_queue_purge(&x25->interrupt_out_queue);
  47        skb_queue_purge(&x25->fragment_queue);
  48}
  49
  50
  51/*
  52 * This routine purges the input queue of those frames that have been
  53 * acknowledged. This replaces the boxes labelled "V(a) <- N(r)" on the
  54 * SDL diagram.
  55*/
  56void x25_frames_acked(struct sock *sk, unsigned short nr)
  57{
  58        struct sk_buff *skb;
  59        struct x25_sock *x25 = x25_sk(sk);
  60        int modulus = x25->neighbour->extended ? X25_EMODULUS : X25_SMODULUS;
  61
  62        /*
  63         * Remove all the ack-ed frames from the ack queue.
  64         */
  65        if (x25->va != nr)
  66                while (skb_peek(&x25->ack_queue) && x25->va != nr) {
  67                        skb = skb_dequeue(&x25->ack_queue);
  68                        kfree_skb(skb);
  69                        x25->va = (x25->va + 1) % modulus;
  70                }
  71}
  72
  73void x25_requeue_frames(struct sock *sk)
  74{
  75        struct sk_buff *skb, *skb_prev = NULL;
  76
  77        /*
  78         * Requeue all the un-ack-ed frames on the output queue to be picked
  79         * up by x25_kick. This arrangement handles the possibility of an empty
  80         * output queue.
  81         */
  82        while ((skb = skb_dequeue(&x25_sk(sk)->ack_queue)) != NULL) {
  83                if (!skb_prev)
  84                        skb_queue_head(&sk->sk_write_queue, skb);
  85                else
  86                        skb_append(skb_prev, skb, &sk->sk_write_queue);
  87                skb_prev = skb;
  88        }
  89}
  90
  91/*
  92 *      Validate that the value of nr is between va and vs. Return true or
  93 *      false for testing.
  94 */
  95int x25_validate_nr(struct sock *sk, unsigned short nr)
  96{
  97        struct x25_sock *x25 = x25_sk(sk);
  98        unsigned short vc = x25->va;
  99        int modulus = x25->neighbour->extended ? X25_EMODULUS : X25_SMODULUS;
 100
 101        while (vc != x25->vs) {
 102                if (nr == vc)
 103                        return 1;
 104                vc = (vc + 1) % modulus;
 105        }
 106
 107        return nr == x25->vs ? 1 : 0;
 108}
 109
 110/*
 111 *  This routine is called when the packet layer internally generates a
 112 *  control frame.
 113 */
 114void x25_write_internal(struct sock *sk, int frametype)
 115{
 116        struct x25_sock *x25 = x25_sk(sk);
 117        struct sk_buff *skb;
 118        unsigned char  *dptr;
 119        unsigned char  facilities[X25_MAX_FAC_LEN];
 120        unsigned char  addresses[1 + X25_ADDR_LEN];
 121        unsigned char  lci1, lci2;
 122        /*
 123         *      Default safe frame size.
 124         */
 125        int len = X25_MAX_L2_LEN + X25_EXT_MIN_LEN;
 126
 127        /*
 128         *      Adjust frame size.
 129         */
 130        switch (frametype) {
 131        case X25_CALL_REQUEST:
 132                len += 1 + X25_ADDR_LEN + X25_MAX_FAC_LEN + X25_MAX_CUD_LEN;
 133                break;
 134        case X25_CALL_ACCEPTED: /* fast sel with no restr on resp */
 135                if (x25->facilities.reverse & 0x80) {
 136                        len += 1 + X25_MAX_FAC_LEN + X25_MAX_CUD_LEN;
 137                } else {
 138                        len += 1 + X25_MAX_FAC_LEN;
 139                }
 140                break;
 141        case X25_CLEAR_REQUEST:
 142        case X25_RESET_REQUEST:
 143                len += 2;
 144                break;
 145        case X25_RR:
 146        case X25_RNR:
 147        case X25_REJ:
 148        case X25_CLEAR_CONFIRMATION:
 149        case X25_INTERRUPT_CONFIRMATION:
 150        case X25_RESET_CONFIRMATION:
 151                break;
 152        default:
 153                pr_err("invalid frame type %02X\n", frametype);
 154                return;
 155        }
 156
 157        if ((skb = alloc_skb(len, GFP_ATOMIC)) == NULL)
 158                return;
 159
 160        /*
 161         *      Space for Ethernet and 802.2 LLC headers.
 162         */
 163        skb_reserve(skb, X25_MAX_L2_LEN);
 164
 165        /*
 166         *      Make space for the GFI and LCI, and fill them in.
 167         */
 168        dptr = skb_put(skb, 2);
 169
 170        lci1 = (x25->lci >> 8) & 0x0F;
 171        lci2 = (x25->lci >> 0) & 0xFF;
 172
 173        if (x25->neighbour->extended) {
 174                *dptr++ = lci1 | X25_GFI_EXTSEQ;
 175                *dptr++ = lci2;
 176        } else {
 177                *dptr++ = lci1 | X25_GFI_STDSEQ;
 178                *dptr++ = lci2;
 179        }
 180
 181        /*
 182         *      Now fill in the frame type specific information.
 183         */
 184        switch (frametype) {
 185
 186                case X25_CALL_REQUEST:
 187                        dptr    = skb_put(skb, 1);
 188                        *dptr++ = X25_CALL_REQUEST;
 189                        len     = x25_addr_aton(addresses, &x25->dest_addr,
 190                                                &x25->source_addr);
 191                        dptr    = skb_put(skb, len);
 192                        memcpy(dptr, addresses, len);
 193                        len     = x25_create_facilities(facilities,
 194                                        &x25->facilities,
 195                                        &x25->dte_facilities,
 196                                        x25->neighbour->global_facil_mask);
 197                        dptr    = skb_put(skb, len);
 198                        memcpy(dptr, facilities, len);
 199                        dptr = skb_put(skb, x25->calluserdata.cudlength);
 200                        memcpy(dptr, x25->calluserdata.cuddata,
 201                               x25->calluserdata.cudlength);
 202                        x25->calluserdata.cudlength = 0;
 203                        break;
 204
 205                case X25_CALL_ACCEPTED:
 206                        dptr    = skb_put(skb, 2);
 207                        *dptr++ = X25_CALL_ACCEPTED;
 208                        *dptr++ = 0x00;         /* Address lengths */
 209                        len     = x25_create_facilities(facilities,
 210                                                        &x25->facilities,
 211                                                        &x25->dte_facilities,
 212                                                        x25->vc_facil_mask);
 213                        dptr    = skb_put(skb, len);
 214                        memcpy(dptr, facilities, len);
 215
 216                        /* fast select with no restriction on response
 217                                allows call user data. Userland must
 218                                ensure it is ours and not theirs */
 219                        if(x25->facilities.reverse & 0x80) {
 220                                dptr = skb_put(skb,
 221                                        x25->calluserdata.cudlength);
 222                                memcpy(dptr, x25->calluserdata.cuddata,
 223                                       x25->calluserdata.cudlength);
 224                        }
 225                        x25->calluserdata.cudlength = 0;
 226                        break;
 227
 228                case X25_CLEAR_REQUEST:
 229                        dptr    = skb_put(skb, 3);
 230                        *dptr++ = frametype;
 231                        *dptr++ = x25->causediag.cause;
 232                        *dptr++ = x25->causediag.diagnostic;
 233                        break;
 234
 235                case X25_RESET_REQUEST:
 236                        dptr    = skb_put(skb, 3);
 237                        *dptr++ = frametype;
 238                        *dptr++ = 0x00;         /* XXX */
 239                        *dptr++ = 0x00;         /* XXX */
 240                        break;
 241
 242                case X25_RR:
 243                case X25_RNR:
 244                case X25_REJ:
 245                        if (x25->neighbour->extended) {
 246                                dptr     = skb_put(skb, 2);
 247                                *dptr++  = frametype;
 248                                *dptr++  = (x25->vr << 1) & 0xFE;
 249                        } else {
 250                                dptr     = skb_put(skb, 1);
 251                                *dptr    = frametype;
 252                                *dptr++ |= (x25->vr << 5) & 0xE0;
 253                        }
 254                        break;
 255
 256                case X25_CLEAR_CONFIRMATION:
 257                case X25_INTERRUPT_CONFIRMATION:
 258                case X25_RESET_CONFIRMATION:
 259                        dptr  = skb_put(skb, 1);
 260                        *dptr = frametype;
 261                        break;
 262        }
 263
 264        x25_transmit_link(skb, x25->neighbour);
 265}
 266
 267/*
 268 *      Unpick the contents of the passed X.25 Packet Layer frame.
 269 */
 270int x25_decode(struct sock *sk, struct sk_buff *skb, int *ns, int *nr, int *q,
 271               int *d, int *m)
 272{
 273        struct x25_sock *x25 = x25_sk(sk);
 274        unsigned char *frame;
 275
 276        if (!pskb_may_pull(skb, X25_STD_MIN_LEN))
 277                return X25_ILLEGAL;
 278        frame = skb->data;
 279
 280        *ns = *nr = *q = *d = *m = 0;
 281
 282        switch (frame[2]) {
 283        case X25_CALL_REQUEST:
 284        case X25_CALL_ACCEPTED:
 285        case X25_CLEAR_REQUEST:
 286        case X25_CLEAR_CONFIRMATION:
 287        case X25_INTERRUPT:
 288        case X25_INTERRUPT_CONFIRMATION:
 289        case X25_RESET_REQUEST:
 290        case X25_RESET_CONFIRMATION:
 291        case X25_RESTART_REQUEST:
 292        case X25_RESTART_CONFIRMATION:
 293        case X25_REGISTRATION_REQUEST:
 294        case X25_REGISTRATION_CONFIRMATION:
 295        case X25_DIAGNOSTIC:
 296                return frame[2];
 297        }
 298
 299        if (x25->neighbour->extended) {
 300                if (frame[2] == X25_RR  ||
 301                    frame[2] == X25_RNR ||
 302                    frame[2] == X25_REJ) {
 303                        if (!pskb_may_pull(skb, X25_EXT_MIN_LEN))
 304                                return X25_ILLEGAL;
 305                        frame = skb->data;
 306
 307                        *nr = (frame[3] >> 1) & 0x7F;
 308                        return frame[2];
 309                }
 310        } else {
 311                if ((frame[2] & 0x1F) == X25_RR  ||
 312                    (frame[2] & 0x1F) == X25_RNR ||
 313                    (frame[2] & 0x1F) == X25_REJ) {
 314                        *nr = (frame[2] >> 5) & 0x07;
 315                        return frame[2] & 0x1F;
 316                }
 317        }
 318
 319        if (x25->neighbour->extended) {
 320                if ((frame[2] & 0x01) == X25_DATA) {
 321                        if (!pskb_may_pull(skb, X25_EXT_MIN_LEN))
 322                                return X25_ILLEGAL;
 323                        frame = skb->data;
 324
 325                        *q  = (frame[0] & X25_Q_BIT) == X25_Q_BIT;
 326                        *d  = (frame[0] & X25_D_BIT) == X25_D_BIT;
 327                        *m  = (frame[3] & X25_EXT_M_BIT) == X25_EXT_M_BIT;
 328                        *nr = (frame[3] >> 1) & 0x7F;
 329                        *ns = (frame[2] >> 1) & 0x7F;
 330                        return X25_DATA;
 331                }
 332        } else {
 333                if ((frame[2] & 0x01) == X25_DATA) {
 334                        *q  = (frame[0] & X25_Q_BIT) == X25_Q_BIT;
 335                        *d  = (frame[0] & X25_D_BIT) == X25_D_BIT;
 336                        *m  = (frame[2] & X25_STD_M_BIT) == X25_STD_M_BIT;
 337                        *nr = (frame[2] >> 5) & 0x07;
 338                        *ns = (frame[2] >> 1) & 0x07;
 339                        return X25_DATA;
 340                }
 341        }
 342
 343        pr_debug("invalid PLP frame %02X %02X %02X\n",
 344               frame[0], frame[1], frame[2]);
 345
 346        return X25_ILLEGAL;
 347}
 348
 349void x25_disconnect(struct sock *sk, int reason, unsigned char cause,
 350                    unsigned char diagnostic)
 351{
 352        struct x25_sock *x25 = x25_sk(sk);
 353
 354        x25_clear_queues(sk);
 355        x25_stop_timer(sk);
 356
 357        x25->lci   = 0;
 358        x25->state = X25_STATE_0;
 359
 360        x25->causediag.cause      = cause;
 361        x25->causediag.diagnostic = diagnostic;
 362
 363        sk->sk_state     = TCP_CLOSE;
 364        sk->sk_err       = reason;
 365        sk->sk_shutdown |= SEND_SHUTDOWN;
 366
 367        if (!sock_flag(sk, SOCK_DEAD)) {
 368                sk->sk_state_change(sk);
 369                sock_set_flag(sk, SOCK_DEAD);
 370        }
 371}
 372
 373/*
 374 * Clear an own-rx-busy condition and tell the peer about this, provided
 375 * that there is a significant amount of free receive buffer space available.
 376 */
 377void x25_check_rbuf(struct sock *sk)
 378{
 379        struct x25_sock *x25 = x25_sk(sk);
 380
 381        if (atomic_read(&sk->sk_rmem_alloc) < (sk->sk_rcvbuf >> 1) &&
 382            (x25->condition & X25_COND_OWN_RX_BUSY)) {
 383                x25->condition &= ~X25_COND_OWN_RX_BUSY;
 384                x25->condition &= ~X25_COND_ACK_PENDING;
 385                x25->vl         = x25->vr;
 386                x25_write_internal(sk, X25_RR);
 387                x25_stop_timer(sk);
 388        }
 389}
 390
 391