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