net/x25/x25_subr.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 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  */
  23
  24 #include <linux/kernel.h>
  25 #include <linux/string.h>
  26 #include <linux/skbuff.h>
  27 #include <net/sock.h>
  28 #include <net/tcp.h>
  29 #include <net/x25.h>
  30
  31 /*
  32  *      This routine purges all of the queues of frames.
  33  */
  34 void x25_clear_queues(struct sock *sk)
  35 {
  36         struct x25_sock *x25 = x25_sk(sk);
  37
  38         skb_queue_purge(&sk->sk_write_queue);
  39         skb_queue_purge(&x25->ack_queue);
  40         skb_queue_purge(&x25->interrupt_in_queue);
  41         skb_queue_purge(&x25->interrupt_out_queue);
  42         skb_queue_purge(&x25->fragment_queue);
  43 }
  44
  45
  46 /*
  47  * This routine purges the input queue of those frames that have been
  48  * acknowledged. This replaces the boxes labelled "V(a) <- N(r)" on the
  49  * SDL diagram.
  50 */
  51 void x25_frames_acked(struct sock *sk, unsigned short nr)
  52 {
  53         struct sk_buff *skb;
  54         struct x25_sock *x25 = x25_sk(sk);
  55         int modulus = x25->neighbour->extended ? X25_EMODULUS : X25_SMODULUS;
  56
  57         /*
  58          * Remove all the ack-ed frames from the ack queue.
  59          */
  60         if (x25->va != nr)
  61                 while (skb_peek(&x25->ack_queue) && x25->va != nr) {
  62                         skb = skb_dequeue(&x25->ack_queue);
  63                         kfree_skb(skb);
  64                         x25->va = (x25->va + 1) % modulus;
  65                 }
  66 }
  67
  68 void x25_requeue_frames(struct sock *sk)
  69 {
  70         struct sk_buff *skb, *skb_prev = NULL;
  71
  72         /*
  73          * Requeue all the un-ack-ed frames on the output queue to be picked
  74          * up by x25_kick. This arrangement handles the possibility of an empty
  75          * output queue.
  76          */
  77         while ((skb = skb_dequeue(&x25_sk(sk)->ack_queue)) != NULL) {
  78                 if (!skb_prev)
  79                         skb_queue_head(&sk->sk_write_queue, skb);
  80                 else
  81                         skb_append(skb_prev, skb);
  82                 skb_prev = skb;
  83         }
  84 }
  85
  86 /*
  87  *      Validate that the value of nr is between va and vs. Return true or
  88  *      false for testing.
  89  */
  90 int x25_validate_nr(struct sock *sk, unsigned short nr)
  91 {
  92         struct x25_sock *x25 = x25_sk(sk);
  93         unsigned short vc = x25->va;
  94         int modulus = x25->neighbour->extended ? X25_EMODULUS : X25_SMODULUS;
  95
  96         while (vc != x25->vs) {
  97                 if (nr == vc)
  98                         return 1;
  99                 vc = (vc + 1) % modulus;
 100         }
 101
 102         return nr == x25->vs ? 1 : 0;
 103 }
 104
 105 /*
 106  *  This routine is called when the packet layer internally generates a
 107  *  control frame.
 108  */
 109 void x25_write_internal(struct sock *sk, int frametype)
 110 {
 111         struct x25_sock *x25 = x25_sk(sk);
 112         struct sk_buff *skb;
 113         unsigned char  *dptr;
 114         unsigned char  facilities[X25_MAX_FAC_LEN];
 115         unsigned char  addresses[1 + X25_ADDR_LEN];
 116         unsigned char  lci1, lci2;
 117         /*
 118          *      Default safe frame size.
 119          */
 120         int len = X25_MAX_L2_LEN + X25_EXT_MIN_LEN;
 121
 122         /*
 123          *      Adjust frame size.
 124          */
 125         switch (frametype) {
 126                 case X25_CALL_REQUEST:
 127                         len += 1 + X25_ADDR_LEN + X25_MAX_FAC_LEN +
 128                                X25_MAX_CUD_LEN;
 129                         break;
 130                 case X25_CALL_ACCEPTED:
 131                         len += 1 + X25_MAX_FAC_LEN + X25_MAX_CUD_LEN;
 132                         break;
 133                 case X25_CLEAR_REQUEST:
 134                 case X25_RESET_REQUEST:
 135                         len += 2;
 136                         break;
 137                 case X25_RR:
 138                 case X25_RNR:
 139                 case X25_REJ:
 140                 case X25_CLEAR_CONFIRMATION:
 141                 case X25_INTERRUPT_CONFIRMATION:
 142                 case X25_RESET_CONFIRMATION:
 143                         break;
 144                 default:
 145                         printk(KERN_ERR "X.25: invalid frame type %02X\n",
 146                                frametype);
 147                         return;
 148         }
 149
 150         if ((skb = alloc_skb(len, GFP_ATOMIC)) == NULL)
 151                 return;
 152
 153         /*
 154          *      Space for Ethernet and 802.2 LLC headers.
 155          */
 156         skb_reserve(skb, X25_MAX_L2_LEN);
 157
 158         /*
 159          *      Make space for the GFI and LCI, and fill them in.
 160          */
 161         dptr = skb_put(skb, 2);
 162
 163         lci1 = (x25->lci >> 8) & 0x0F;
 164         lci2 = (x25->lci >> 0) & 0xFF;
 165
 166         if (x25->neighbour->extended) {
 167                 *dptr++ = lci1 | X25_GFI_EXTSEQ;
 168                 *dptr++ = lci2;
 169         } else {
 170                 *dptr++ = lci1 | X25_GFI_STDSEQ;
 171                 *dptr++ = lci2;
 172         }
 173
 174         /*
 175          *      Now fill in the frame type specific information.
 176          */
 177         switch (frametype) {
 178
 179                 case X25_CALL_REQUEST:
 180                         dptr    = skb_put(skb, 1);
 181                         *dptr++ = X25_CALL_REQUEST;
 182                         len     = x25_addr_aton(addresses, &x25->dest_addr,
 183                                                 &x25->source_addr);
 184                         dptr    = skb_put(skb, len);
 185                         memcpy(dptr, addresses, len);
 186                         len     = x25_create_facilities(facilities,
 187                                                         &x25->facilities,
 188                                              x25->neighbour->global_facil_mask);
 189                         dptr    = skb_put(skb, len);
 190                         memcpy(dptr, facilities, len);
 191                         dptr = skb_put(skb, x25->calluserdata.cudlength);
 192                         memcpy(dptr, x25->calluserdata.cuddata,
 193                                x25->calluserdata.cudlength);
 194                         x25->calluserdata.cudlength = 0;
 195                         break;
 196
 197                 case X25_CALL_ACCEPTED:
 198                         dptr    = skb_put(skb, 2);
 199                         *dptr++ = X25_CALL_ACCEPTED;
 200                         *dptr++ = 0x00;         /* Address lengths */
 201                         len     = x25_create_facilities(facilities,
 202                                                         &x25->facilities,
 203                                                         x25->vc_facil_mask);
 204                         dptr    = skb_put(skb, len);
 205                         memcpy(dptr, facilities, len);
 206                         dptr = skb_put(skb, x25->calluserdata.cudlength);
 207                         memcpy(dptr, x25->calluserdata.cuddata,
 208                                x25->calluserdata.cudlength);
 209                         x25->calluserdata.cudlength = 0;
 210                         break;
 211
 212                 case X25_CLEAR_REQUEST:
 213                 case X25_RESET_REQUEST:
 214                         dptr    = skb_put(skb, 3);
 215                         *dptr++ = frametype;
 216                         *dptr++ = 0x00;         /* XXX */
 217                         *dptr++ = 0x00;         /* XXX */
 218                         break;
 219
 220                 case X25_RR:
 221                 case X25_RNR:
 222                 case X25_REJ:
 223                         if (x25->neighbour->extended) {
 224                                 dptr     = skb_put(skb, 2);
 225                                 *dptr++  = frametype;
 226                                 *dptr++  = (x25->vr << 1) & 0xFE;
 227                         } else {
 228                                 dptr     = skb_put(skb, 1);
 229                                 *dptr    = frametype;
 230                                 *dptr++ |= (x25->vr << 5) & 0xE0;
 231                         }
 232                         break;
 233
 234                 case X25_CLEAR_CONFIRMATION:
 235                 case X25_INTERRUPT_CONFIRMATION:
 236                 case X25_RESET_CONFIRMATION:
 237                         dptr  = skb_put(skb, 1);
 238                         *dptr = frametype;
 239                         break;
 240         }
 241
 242         x25_transmit_link(skb, x25->neighbour);
 243 }
 244
 245 /*
 246  *      Unpick the contents of the passed X.25 Packet Layer frame.
 247  */
 248 int x25_decode(struct sock *sk, struct sk_buff *skb, int *ns, int *nr, int *q,
 249                int *d, int *m)
 250 {
 251         struct x25_sock *x25 = x25_sk(sk);
 252         unsigned char *frame = skb->data;
 253
 254         *ns = *nr = *q = *d = *m = 0;
 255
 256         switch (frame[2]) {
 257                 case X25_CALL_REQUEST:
 258                 case X25_CALL_ACCEPTED:
 259                 case X25_CLEAR_REQUEST:
 260                 case X25_CLEAR_CONFIRMATION:
 261                 case X25_INTERRUPT:
 262                 case X25_INTERRUPT_CONFIRMATION:
 263                 case X25_RESET_REQUEST:
 264                 case X25_RESET_CONFIRMATION:
 265                 case X25_RESTART_REQUEST:
 266                 case X25_RESTART_CONFIRMATION:
 267                 case X25_REGISTRATION_REQUEST:
 268                 case X25_REGISTRATION_CONFIRMATION:
 269                 case X25_DIAGNOSTIC:
 270                         return frame[2];
 271         }
 272
 273         if (x25->neighbour->extended) {
 274                 if (frame[2] == X25_RR  ||
 275                     frame[2] == X25_RNR ||
 276                     frame[2] == X25_REJ) {
 277                         *nr = (frame[3] >> 1) & 0x7F;
 278                         return frame[2];
 279                 }
 280         } else {
 281                 if ((frame[2] & 0x1F) == X25_RR  ||
 282                     (frame[2] & 0x1F) == X25_RNR ||
 283                     (frame[2] & 0x1F) == X25_REJ) {
 284                         *nr = (frame[2] >> 5) & 0x07;
 285                         return frame[2] & 0x1F;
 286                 }
 287         }
 288
 289         if (x25->neighbour->extended) {
 290                 if ((frame[2] & 0x01) == X25_DATA) {
 291                         *q  = (frame[0] & X25_Q_BIT) == X25_Q_BIT;
 292                         *d  = (frame[0] & X25_D_BIT) == X25_D_BIT;
 293                         *m  = (frame[3] & X25_EXT_M_BIT) == X25_EXT_M_BIT;
 294                         *nr = (frame[3] >> 1) & 0x7F;
 295                         *ns = (frame[2] >> 1) & 0x7F;
 296                         return X25_DATA;
 297                 }
 298         } else {
 299                 if ((frame[2] & 0x01) == X25_DATA) {
 300                         *q  = (frame[0] & X25_Q_BIT) == X25_Q_BIT;
 301                         *d  = (frame[0] & X25_D_BIT) == X25_D_BIT;
 302                         *m  = (frame[2] & X25_STD_M_BIT) == X25_STD_M_BIT;
 303                         *nr = (frame[2] >> 5) & 0x07;
 304                         *ns = (frame[2] >> 1) & 0x07;
 305                         return X25_DATA;
 306                 }
 307         }
 308
 309         printk(KERN_DEBUG "X.25: invalid PLP frame %02X %02X %02X\n",
 310                frame[0], frame[1], frame[2]);
 311
 312         return X25_ILLEGAL;
 313 }
 314
 315 void x25_disconnect(struct sock *sk, int reason, unsigned char cause,
 316                     unsigned char diagnostic)
 317 {
 318         struct x25_sock *x25 = x25_sk(sk);
 319
 320         x25_clear_queues(sk);
 321         x25_stop_timer(sk);
 322
 323         x25->lci   = 0;
 324         x25->state = X25_STATE_0;
 325
 326         x25->causediag.cause      = cause;
 327         x25->causediag.diagnostic = diagnostic;
 328
 329         sk->sk_state     = TCP_CLOSE;
 330         sk->sk_err       = reason;
 331         sk->sk_shutdown |= SEND_SHUTDOWN;
 332
 333         if (!sock_flag(sk, SOCK_DEAD)) {
 334                 sk->sk_state_change(sk);
 335                 sock_set_flag(sk, SOCK_DEAD);
 336         }
 337 }
 338
 339 /*
 340  * Clear an own-rx-busy condition and tell the peer about this, provided
 341  * that there is a significant amount of free receive buffer space available.
 342  */
 343 void x25_check_rbuf(struct sock *sk)
 344 {
 345         struct x25_sock *x25 = x25_sk(sk);
 346
 347         if (atomic_read(&sk->sk_rmem_alloc) < (sk->sk_rcvbuf / 2) &&
 348             (x25->condition & X25_COND_OWN_RX_BUSY)) {
 349                 x25->condition &= ~X25_COND_OWN_RX_BUSY;
 350                 x25->condition &= ~X25_COND_ACK_PENDING;
 351                 x25->vl         = x25->vr;
 352                 x25_write_internal(sk, X25_RR);
 353                 x25_stop_timer(sk);
 354         }
 355 }
 356
 357 /*
 358  * Compare 2 calluserdata structures, used to find correct listening sockets
 359  * when call user data is used.
 360  */
 361 int x25_check_calluserdata(struct x25_calluserdata *ours, struct x25_calluserdata *theirs)
 362 {
 363         int i;
 364         if (ours->cudlength != theirs->cudlength)
 365                 return 0;
 366
 367         for (i=0;i<ours->cudlength;i++) {
 368                 if (ours->cuddata[i] != theirs->cuddata[i]) {
 369                         return 0;
 370                 }
 371         }
 372         return 1;
 373 }
 374