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