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 +
 131                                X25_MAX_CUD_LEN;
 132                         break;
 133                 case X25_CALL_ACCEPTED: /* fast sel with no restr on resp */
 134                         if(x25->facilities.reverse & 0x80) {
 135                                 len += 1 + X25_MAX_FAC_LEN + X25_MAX_CUD_LEN;
 136                         } else {
 137                                 len += 1 + X25_MAX_FAC_LEN;
 138                         }
 139                         break;
 140                 case X25_CLEAR_REQUEST:
 141                 case X25_RESET_REQUEST:
 142                         len += 2;
 143                         break;
 144                 case X25_RR:
 145                 case X25_RNR:
 146                 case X25_REJ:
 147                 case X25_CLEAR_CONFIRMATION:
 148                 case X25_INTERRUPT_CONFIRMATION:
 149                 case X25_RESET_CONFIRMATION:
 150                         break;
 151                 default:
 152                         printk(KERN_ERR "X.25: invalid frame type %02X\n",
 153                                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  */
 270 int 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 = skb->data;
 275
 276         *ns = *nr = *q = *d = *m = 0;
 277
 278         switch (frame[2]) {
 279                 case X25_CALL_REQUEST:
 280                 case X25_CALL_ACCEPTED:
 281                 case X25_CLEAR_REQUEST:
 282                 case X25_CLEAR_CONFIRMATION:
 283                 case X25_INTERRUPT:
 284                 case X25_INTERRUPT_CONFIRMATION:
 285                 case X25_RESET_REQUEST:
 286                 case X25_RESET_CONFIRMATION:
 287                 case X25_RESTART_REQUEST:
 288                 case X25_RESTART_CONFIRMATION:
 289                 case X25_REGISTRATION_REQUEST:
 290                 case X25_REGISTRATION_CONFIRMATION:
 291                 case X25_DIAGNOSTIC:
 292                         return frame[2];
 293         }
 294
 295         if (x25->neighbour->extended) {
 296                 if (frame[2] == X25_RR  ||
 297                     frame[2] == X25_RNR ||
 298                     frame[2] == X25_REJ) {
 299                         *nr = (frame[3] >> 1) & 0x7F;
 300                         return frame[2];
 301                 }
 302         } else {
 303                 if ((frame[2] & 0x1F) == X25_RR  ||
 304                     (frame[2] & 0x1F) == X25_RNR ||
 305                     (frame[2] & 0x1F) == X25_REJ) {
 306                         *nr = (frame[2] >> 5) & 0x07;
 307                         return frame[2] & 0x1F;
 308                 }
 309         }
 310
 311         if (x25->neighbour->extended) {
 312                 if ((frame[2] & 0x01) == X25_DATA) {
 313                         *q  = (frame[0] & X25_Q_BIT) == X25_Q_BIT;
 314                         *d  = (frame[0] & X25_D_BIT) == X25_D_BIT;
 315                         *m  = (frame[3] & X25_EXT_M_BIT) == X25_EXT_M_BIT;
 316                         *nr = (frame[3] >> 1) & 0x7F;
 317                         *ns = (frame[2] >> 1) & 0x7F;
 318                         return X25_DATA;
 319                 }
 320         } else {
 321                 if ((frame[2] & 0x01) == X25_DATA) {
 322                         *q  = (frame[0] & X25_Q_BIT) == X25_Q_BIT;
 323                         *d  = (frame[0] & X25_D_BIT) == X25_D_BIT;
 324                         *m  = (frame[2] & X25_STD_M_BIT) == X25_STD_M_BIT;
 325                         *nr = (frame[2] >> 5) & 0x07;
 326                         *ns = (frame[2] >> 1) & 0x07;
 327                         return X25_DATA;
 328                 }
 329         }
 330
 331         printk(KERN_DEBUG "X.25: invalid PLP frame %02X %02X %02X\n",
 332                frame[0], frame[1], frame[2]);
 333
 334         return X25_ILLEGAL;
 335 }
 336
 337 void x25_disconnect(struct sock *sk, int reason, unsigned char cause,
 338                     unsigned char diagnostic)
 339 {
 340         struct x25_sock *x25 = x25_sk(sk);
 341
 342         x25_clear_queues(sk);
 343         x25_stop_timer(sk);
 344
 345         x25->lci   = 0;
 346         x25->state = X25_STATE_0;
 347
 348         x25->causediag.cause      = cause;
 349         x25->causediag.diagnostic = diagnostic;
 350
 351         sk->sk_state     = TCP_CLOSE;
 352         sk->sk_err       = reason;
 353         sk->sk_shutdown |= SEND_SHUTDOWN;
 354
 355         if (!sock_flag(sk, SOCK_DEAD)) {
 356                 sk->sk_state_change(sk);
 357                 sock_set_flag(sk, SOCK_DEAD);
 358         }
 359 }
 360
 361 /*
 362  * Clear an own-rx-busy condition and tell the peer about this, provided
 363  * that there is a significant amount of free receive buffer space available.
 364  */
 365 void x25_check_rbuf(struct sock *sk)
 366 {
 367         struct x25_sock *x25 = x25_sk(sk);
 368
 369         if (atomic_read(&sk->sk_rmem_alloc) < (sk->sk_rcvbuf >> 1) &&
 370             (x25->condition & X25_COND_OWN_RX_BUSY)) {
 371                 x25->condition &= ~X25_COND_OWN_RX_BUSY;
 372                 x25->condition &= ~X25_COND_ACK_PENDING;
 373                 x25->vl         = x25->vr;
 374                 x25_write_internal(sk, X25_RR);
 375                 x25_stop_timer(sk);
 376         }
 377 }
 378