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/errno.h>
  25 #include <linux/types.h>
  26 #include <linux/socket.h>
  27 #include <linux/in.h>
  28 #include <linux/kernel.h>
  29 #include <linux/sched.h>
  30 #include <linux/timer.h>
  31 #include <linux/string.h>
  32 #include <linux/sockios.h>
  33 #include <linux/net.h>
  34 #include <linux/inet.h>
  35 #include <linux/netdevice.h>
  36 #include <linux/skbuff.h>
  37 #include <net/sock.h>
  38 #include <net/tcp.h>
  39 #include <asm/system.h>
  40 #include <linux/fcntl.h>
  41 #include <linux/mm.h>
  42 #include <linux/interrupt.h>
  43 #include <net/x25.h>
  44
  45 /*
  46  *      This routine purges all of the queues of frames.
  47  */
  48 void x25_clear_queues(struct sock *sk)
  49 {
  50         struct x25_opt *x25 = x25_sk(sk);
  51
  52         skb_queue_purge(&sk->sk_write_queue);
  53         skb_queue_purge(&x25->ack_queue);
  54         skb_queue_purge(&x25->interrupt_in_queue);
  55         skb_queue_purge(&x25->interrupt_out_queue);
  56         skb_queue_purge(&x25->fragment_queue);
  57 }
  58
  59
  60 /*
  61  * This routine purges the input queue of those frames that have been
  62  * acknowledged. This replaces the boxes labelled "V(a) <- N(r)" on the
  63  * SDL diagram.
  64 */
  65 void x25_frames_acked(struct sock *sk, unsigned short nr)
  66 {
  67         struct sk_buff *skb;
  68         struct x25_opt *x25 = x25_sk(sk);
  69         int modulus = x25->neighbour->extended ? X25_EMODULUS : X25_SMODULUS;
  70
  71         /*
  72          * Remove all the ack-ed frames from the ack queue.
  73          */
  74         if (x25->va != nr)
  75                 while (skb_peek(&x25->ack_queue) && x25->va != nr) {
  76                         skb = skb_dequeue(&x25->ack_queue);
  77                         kfree_skb(skb);
  78                         x25->va = (x25->va + 1) % modulus;
  79                 }
  80 }
  81
  82 void x25_requeue_frames(struct sock *sk)
  83 {
  84         struct sk_buff *skb, *skb_prev = NULL;
  85
  86         /*
  87          * Requeue all the un-ack-ed frames on the output queue to be picked
  88          * up by x25_kick. This arrangement handles the possibility of an empty
  89          * output queue.
  90          */
  91         while ((skb = skb_dequeue(&x25_sk(sk)->ack_queue)) != NULL) {
  92                 if (!skb_prev)
  93                         skb_queue_head(&sk->sk_write_queue, skb);
  94                 else
  95                         skb_append(skb_prev, skb);
  96                 skb_prev = skb;
  97         }
  98 }
  99
 100 /*
 101  *      Validate that the value of nr is between va and vs. Return true or
 102  *      false for testing.
 103  */
 104 int x25_validate_nr(struct sock *sk, unsigned short nr)
 105 {
 106         struct x25_opt *x25 = x25_sk(sk);
 107         unsigned short vc = x25->va;
 108         int modulus = x25->neighbour->extended ? X25_EMODULUS : X25_SMODULUS;
 109
 110         while (vc != x25->vs) {
 111                 if (nr == vc)
 112                         return 1;
 113                 vc = (vc + 1) % modulus;
 114         }
 115
 116         return nr == x25->vs ? 1 : 0;
 117 }
 118
 119 /*
 120  *  This routine is called when the packet layer internally generates a
 121  *  control frame.
 122  */
 123 void x25_write_internal(struct sock *sk, int frametype)
 124 {
 125         struct x25_opt *x25 = x25_sk(sk);
 126         struct sk_buff *skb;
 127         unsigned char  *dptr;
 128         unsigned char  facilities[X25_MAX_FAC_LEN];
 129         unsigned char  addresses[1 + X25_ADDR_LEN];
 130         unsigned char  lci1, lci2;
 131         /*
 132          *      Default safe frame size.
 133          */
 134         int len = X25_MAX_L2_LEN + X25_EXT_MIN_LEN;
 135
 136         /*
 137          *      Adjust frame size.
 138          */
 139         switch (frametype) {
 140                 case X25_CALL_REQUEST:
 141                         len += 1 + X25_ADDR_LEN + X25_MAX_FAC_LEN +
 142                                X25_MAX_CUD_LEN;
 143                         break;
 144                 case X25_CALL_ACCEPTED:
 145                         len += 1 + X25_MAX_FAC_LEN + X25_MAX_CUD_LEN;
 146                         break;
 147                 case X25_CLEAR_REQUEST:
 148                 case X25_RESET_REQUEST:
 149                         len += 2;
 150                         break;
 151                 case X25_RR:
 152                 case X25_RNR:
 153                 case X25_REJ:
 154                 case X25_CLEAR_CONFIRMATION:
 155                 case X25_INTERRUPT_CONFIRMATION:
 156                 case X25_RESET_CONFIRMATION:
 157                         break;
 158                 default:
 159                         printk(KERN_ERR "X.25: invalid frame type %02X\n",
 160                                frametype);
 161                         return;
 162         }
 163
 164         if ((skb = alloc_skb(len, GFP_ATOMIC)) == NULL)
 165                 return;
 166
 167         /*
 168          *      Space for Ethernet and 802.2 LLC headers.
 169          */
 170         skb_reserve(skb, X25_MAX_L2_LEN);
 171
 172         /*
 173          *      Make space for the GFI and LCI, and fill them in.
 174          */
 175         dptr = skb_put(skb, 2);
 176
 177         lci1 = (x25->lci >> 8) & 0x0F;
 178         lci2 = (x25->lci >> 0) & 0xFF;
 179
 180         if (x25->neighbour->extended) {
 181                 *dptr++ = lci1 | X25_GFI_EXTSEQ;
 182                 *dptr++ = lci2;
 183         } else {
 184                 *dptr++ = lci1 | X25_GFI_STDSEQ;
 185                 *dptr++ = lci2;
 186         }
 187
 188         /*
 189          *      Now fill in the frame type specific information.
 190          */
 191         switch (frametype) {
 192
 193                 case X25_CALL_REQUEST:
 194                         dptr    = skb_put(skb, 1);
 195                         *dptr++ = X25_CALL_REQUEST;
 196                         len     = x25_addr_aton(addresses, &x25->dest_addr,
 197                                                 &x25->source_addr);
 198                         dptr    = skb_put(skb, len);
 199                         memcpy(dptr, addresses, len);
 200                         len     = x25_create_facilities(facilities,
 201                                                         &x25->facilities,
 202                                              x25->neighbour->global_facil_mask);
 203                         dptr    = skb_put(skb, len);
 204                         memcpy(dptr, facilities, len);
 205                         dptr = skb_put(skb, x25->calluserdata.cudlength);
 206                         memcpy(dptr, x25->calluserdata.cuddata,
 207                                x25->calluserdata.cudlength);
 208                         x25->calluserdata.cudlength = 0;
 209                         break;
 210
 211                 case X25_CALL_ACCEPTED:
 212                         dptr    = skb_put(skb, 2);
 213                         *dptr++ = X25_CALL_ACCEPTED;
 214                         *dptr++ = 0x00;         /* Address lengths */
 215                         len     = x25_create_facilities(facilities,
 216                                                         &x25->facilities,
 217                                                         x25->vc_facil_mask);
 218                         dptr    = skb_put(skb, len);
 219                         memcpy(dptr, facilities, len);
 220                         dptr = skb_put(skb, x25->calluserdata.cudlength);
 221                         memcpy(dptr, x25->calluserdata.cuddata,
 222                                x25->calluserdata.cudlength);
 223                         x25->calluserdata.cudlength = 0;
 224                         break;
 225
 226                 case X25_CLEAR_REQUEST:
 227                 case X25_RESET_REQUEST:
 228                         dptr    = skb_put(skb, 3);
 229                         *dptr++ = frametype;
 230                         *dptr++ = 0x00;         /* XXX */
 231                         *dptr++ = 0x00;         /* XXX */
 232                         break;
 233
 234                 case X25_RR:
 235                 case X25_RNR:
 236                 case X25_REJ:
 237                         if (x25->neighbour->extended) {
 238                                 dptr     = skb_put(skb, 2);
 239                                 *dptr++  = frametype;
 240                                 *dptr++  = (x25->vr << 1) & 0xFE;
 241                         } else {
 242                                 dptr     = skb_put(skb, 1);
 243                                 *dptr    = frametype;
 244                                 *dptr++ |= (x25->vr << 5) & 0xE0;
 245                         }
 246                         break;
 247
 248                 case X25_CLEAR_CONFIRMATION:
 249                 case X25_INTERRUPT_CONFIRMATION:
 250                 case X25_RESET_CONFIRMATION:
 251                         dptr  = skb_put(skb, 1);
 252                         *dptr = frametype;
 253                         break;
 254         }
 255
 256         x25_transmit_link(skb, x25->neighbour);
 257 }
 258
 259 /*
 260  *      Unpick the contents of the passed X.25 Packet Layer frame.
 261  */
 262 int x25_decode(struct sock *sk, struct sk_buff *skb, int *ns, int *nr, int *q,
 263                int *d, int *m)
 264 {
 265         struct x25_opt *x25 = x25_sk(sk);
 266         unsigned char *frame = skb->data;
 267
 268         *ns = *nr = *q = *d = *m = 0;
 269
 270         switch (frame[2]) {
 271                 case X25_CALL_REQUEST:
 272                 case X25_CALL_ACCEPTED:
 273                 case X25_CLEAR_REQUEST:
 274                 case X25_CLEAR_CONFIRMATION:
 275                 case X25_INTERRUPT:
 276                 case X25_INTERRUPT_CONFIRMATION:
 277                 case X25_RESET_REQUEST:
 278                 case X25_RESET_CONFIRMATION:
 279                 case X25_RESTART_REQUEST:
 280                 case X25_RESTART_CONFIRMATION:
 281                 case X25_REGISTRATION_REQUEST:
 282                 case X25_REGISTRATION_CONFIRMATION:
 283                 case X25_DIAGNOSTIC:
 284                         return frame[2];
 285         }
 286
 287         if (x25->neighbour->extended) {
 288                 if (frame[2] == X25_RR  ||
 289                     frame[2] == X25_RNR ||
 290                     frame[2] == X25_REJ) {
 291                         *nr = (frame[3] >> 1) & 0x7F;
 292                         return frame[2];
 293                 }
 294         } else {
 295                 if ((frame[2] & 0x1F) == X25_RR  ||
 296                     (frame[2] & 0x1F) == X25_RNR ||
 297                     (frame[2] & 0x1F) == X25_REJ) {
 298                         *nr = (frame[2] >> 5) & 0x07;
 299                         return frame[2] & 0x1F;
 300                 }
 301         }
 302
 303         if (x25->neighbour->extended) {
 304                 if ((frame[2] & 0x01) == X25_DATA) {
 305                         *q  = (frame[0] & X25_Q_BIT) == X25_Q_BIT;
 306                         *d  = (frame[0] & X25_D_BIT) == X25_D_BIT;
 307                         *m  = (frame[3] & X25_EXT_M_BIT) == X25_EXT_M_BIT;
 308                         *nr = (frame[3] >> 1) & 0x7F;
 309                         *ns = (frame[2] >> 1) & 0x7F;
 310                         return X25_DATA;
 311                 }
 312         } else {
 313                 if ((frame[2] & 0x01) == X25_DATA) {
 314                         *q  = (frame[0] & X25_Q_BIT) == X25_Q_BIT;
 315                         *d  = (frame[0] & X25_D_BIT) == X25_D_BIT;
 316                         *m  = (frame[2] & X25_STD_M_BIT) == X25_STD_M_BIT;
 317                         *nr = (frame[2] >> 5) & 0x07;
 318                         *ns = (frame[2] >> 1) & 0x07;
 319                         return X25_DATA;
 320                 }
 321         }
 322
 323         printk(KERN_DEBUG "X.25: invalid PLP frame %02X %02X %02X\n",
 324                frame[0], frame[1], frame[2]);
 325
 326         return X25_ILLEGAL;
 327 }
 328
 329 void x25_disconnect(struct sock *sk, int reason, unsigned char cause,
 330                     unsigned char diagnostic)
 331 {
 332         struct x25_opt *x25 = x25_sk(sk);
 333
 334         x25_clear_queues(sk);
 335         x25_stop_timer(sk);
 336
 337         x25->lci   = 0;
 338         x25->state = X25_STATE_0;
 339
 340         x25->causediag.cause      = cause;
 341         x25->causediag.diagnostic = diagnostic;
 342
 343         sk->sk_state     = TCP_CLOSE;
 344         sk->sk_err       = reason;
 345         sk->sk_shutdown |= SEND_SHUTDOWN;
 346
 347         if (!sock_flag(sk, SOCK_DEAD)) {
 348                 sk->sk_state_change(sk);
 349                 sock_set_flag(sk, SOCK_DEAD);
 350         }
 351 }
 352
 353 /*
 354  * Clear an own-rx-busy condition and tell the peer about this, provided
 355  * that there is a significant amount of free receive buffer space available.
 356  */
 357 void x25_check_rbuf(struct sock *sk)
 358 {
 359         struct x25_opt *x25 = x25_sk(sk);
 360
 361         if (atomic_read(&sk->sk_rmem_alloc) < (sk->sk_rcvbuf / 2) &&
 362             (x25->condition & X25_COND_OWN_RX_BUSY)) {
 363                 x25->condition &= ~X25_COND_OWN_RX_BUSY;
 364                 x25->condition &= ~X25_COND_ACK_PENDING;
 365                 x25->vl         = x25->vr;
 366                 x25_write_internal(sk, X25_RR);
 367                 x25_stop_timer(sk);
 368         }
 369 }