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 #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  */
  39 void 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 */
  56 void 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
  73 void 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  */
  95 int 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  */
 114 void 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  */
 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;
 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
 349 void 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  */
 377 void 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