i386/linux/linux-2.3.21/net/ax25/ax25_out.c

   1 /*
   2  *      AX.25 release 037
   3  *
   4  *      This code REQUIRES 2.1.15 or higher/ NET3.038
   5  *
   6  *      This module:
   7  *              This module is free software; you can redistribute it and/or
   8  *              modify it under the terms of the GNU General Public License
   9  *              as published by the Free Software Foundation; either version
  10  *              2 of the License, or (at your option) any later version.
  11  *
  12  *      Most of this code is based on the SDL diagrams published in the 7th
  13  *      ARRL Computer Networking Conference papers. The diagrams have mistakes
  14  *      in them, but are mostly correct. Before you modify the code could you
  15  *      read the SDL diagrams as the code is not obvious and probably very
  16  *      easy to break;
  17  *
  18  *      History
  19  *      AX.25 028a      Jonathan(G4KLX) New state machine based on SDL diagrams.
  20  *      AX.25 029       Alan(GW4PTS)    Switched to KA9Q constant names.
  21  *                      Jonathan(G4KLX) Only poll when window is full.
  22  *      AX.25 030       Jonathan(G4KLX) Added fragmentation to ax25_output.
  23  *                                      Added support for extended AX.25.
  24  *      AX.25 031       Joerg(DL1BKE)   Added DAMA support
  25  *                      Joerg(DL1BKE)   Modified fragmenter to fragment vanilla
  26  *                                      AX.25 I-Frames. Added PACLEN parameter.
  27  *                      Joerg(DL1BKE)   Fixed a problem with buffer allocation
  28  *                                      for fragments.
  29  *      AX.25 037       Jonathan(G4KLX) New timer architecture.
  30  *                      Joerg(DL1BKE)   Fixed DAMA Slave mode: will work
  31  *                                      on non-DAMA interfaces like AX25L2V2
  32  *                                      again (this behaviour is _required_).
  33  *                      Joerg(DL1BKE)   ax25_check_iframes_acked() returns a
  34  *                                      value now (for DAMA n2count handling)
  35  */
  36
  37 #include <linux/config.h>
  38 #if defined(CONFIG_AX25) || defined(CONFIG_AX25_MODULE)
  39 #include <linux/errno.h>
  40 #include <linux/types.h>
  41 #include <linux/socket.h>
  42 #include <linux/in.h>
  43 #include <linux/kernel.h>
  44 #include <linux/sched.h>
  45 #include <linux/timer.h>
  46 #include <linux/string.h>
  47 #include <linux/sockios.h>
  48 #include <linux/net.h>
  49 #include <net/ax25.h>
  50 #include <linux/inet.h>
  51 #include <linux/netdevice.h>
  52 #include <linux/skbuff.h>
  53 #include <linux/netfilter.h>
  54 #include <net/sock.h>
  55 #include <asm/uaccess.h>
  56 #include <asm/system.h>
  57 #include <linux/fcntl.h>
  58 #include <linux/mm.h>
  59 #include <linux/interrupt.h>
  60
  61 ax25_cb *ax25_send_frame(struct sk_buff *skb, int paclen, ax25_address *src, ax25_address *dest, ax25_digi *digi, struct net_device *dev)
  62 {
  63         ax25_dev *ax25_dev;
  64         ax25_cb *ax25;
  65
  66         /*
  67          * Take the default packet length for the device if zero is
  68          * specified.
  69          */
  70         if (paclen == 0) {
  71                 if ((ax25_dev = ax25_dev_ax25dev(dev)) == NULL)
  72                         return NULL;
  73
  74                 paclen = ax25_dev->values[AX25_VALUES_PACLEN];
  75         }
  76
  77         /*
  78          * Look for an existing connection.
  79          */
  80         if ((ax25 = ax25_find_cb(src, dest, digi, dev)) != NULL) {
  81                 ax25_output(ax25, paclen, skb);
  82                 return ax25;            /* It already existed */
  83         }
  84
  85         if ((ax25_dev = ax25_dev_ax25dev(dev)) == NULL)
  86                 return NULL;
  87
  88         if ((ax25 = ax25_create_cb()) == NULL)
  89                 return NULL;
  90
  91         ax25_fillin_cb(ax25, ax25_dev);
  92
  93         ax25->source_addr = *src;
  94         ax25->dest_addr   = *dest;
  95
  96         if (digi != NULL) {
  97                 if ((ax25->digipeat = kmalloc(sizeof(ax25_digi), GFP_ATOMIC)) == NULL) {
  98                         ax25_free_cb(ax25);
  99                         return NULL;
 100                 }
 101                 *ax25->digipeat = *digi;
 102         }
 103
 104         switch (ax25->ax25_dev->values[AX25_VALUES_PROTOCOL]) {
 105                 case AX25_PROTO_STD_SIMPLEX:
 106                 case AX25_PROTO_STD_DUPLEX:
 107                         ax25_std_establish_data_link(ax25);
 108                         break;
 109
 110 #ifdef CONFIG_AX25_DAMA_SLAVE
 111                 case AX25_PROTO_DAMA_SLAVE:
 112                         if (ax25_dev->dama.slave)
 113                                 ax25_ds_establish_data_link(ax25);
 114                         else
 115                                 ax25_std_establish_data_link(ax25);
 116                         break;
 117 #endif
 118         }
 119
 120         ax25_insert_socket(ax25);
 121
 122         ax25->state = AX25_STATE_1;
 123
 124         ax25_start_heartbeat(ax25);
 125
 126         ax25_output(ax25, paclen, skb);
 127
 128         return ax25;                    /* We had to create it */
 129 }
 130
 131 /*
 132  *      All outgoing AX.25 I frames pass via this routine. Therefore this is
 133  *      where the fragmentation of frames takes place. If fragment is set to
 134  *      zero then we are not allowed to do fragmentation, even if the frame
 135  *      is too large.
 136  */
 137 void ax25_output(ax25_cb *ax25, int paclen, struct sk_buff *skb)
 138 {
 139         struct sk_buff *skbn;
 140         unsigned char *p;
 141         int frontlen, len, fragno, ka9qfrag, first = 1;
 142         long flags;
 143
 144         if ((skb->len - 1) > paclen) {
 145                 if (*skb->data == AX25_P_TEXT) {
 146                         skb_pull(skb, 1); /* skip PID */
 147                         ka9qfrag = 0;
 148                 } else {
 149                         paclen -= 2;    /* Allow for fragment control info */
 150                         ka9qfrag = 1;
 151                 }
 152
 153                 fragno = skb->len / paclen;
 154                 if (skb->len % paclen == 0) fragno--;
 155
 156                 frontlen = skb_headroom(skb);   /* Address space + CTRL */
 157
 158                 while (skb->len > 0) {
 159                         save_flags(flags);
 160                         cli();
 161
 162                         if ((skbn = alloc_skb(paclen + 2 + frontlen, GFP_ATOMIC)) == NULL) {
 163                                 restore_flags(flags);
 164                                 printk(KERN_CRIT "AX.25: ax25_output - out of memory\n");
 165                                 return;
 166                         }
 167
 168                         if (skb->sk != NULL)
 169                                 skb_set_owner_w(skbn, skb->sk);
 170
 171                         restore_flags(flags);
 172
 173                         len = (paclen > skb->len) ? skb->len : paclen;
 174
 175                         if (ka9qfrag == 1) {
 176                                 skb_reserve(skbn, frontlen + 2);
 177
 178                                 memcpy(skb_put(skbn, len), skb->data, len);
 179                                 p = skb_push(skbn, 2);
 180
 181                                 *p++ = AX25_P_SEGMENT;
 182
 183                                 *p = fragno--;
 184                                 if (first) {
 185                                         *p |= AX25_SEG_FIRST;
 186                                         first = 0;
 187                                 }
 188                         } else {
 189                                 skb_reserve(skbn, frontlen + 1);
 190                                 memcpy(skb_put(skbn, len), skb->data, len);
 191                                 p = skb_push(skbn, 1);
 192                                 *p = AX25_P_TEXT;
 193                         }
 194
 195                         skb_pull(skb, len);
 196                         skb_queue_tail(&ax25->write_queue, skbn); /* Throw it on the queue */
 197                 }
 198
 199                 kfree_skb(skb);
 200         } else {
 201                 skb_queue_tail(&ax25->write_queue, skb);          /* Throw it on the queue */
 202         }
 203
 204         switch (ax25->ax25_dev->values[AX25_VALUES_PROTOCOL]) {
 205                 case AX25_PROTO_STD_SIMPLEX:
 206                 case AX25_PROTO_STD_DUPLEX:
 207                         ax25_kick(ax25);
 208                         break;
 209
 210 #ifdef CONFIG_AX25_DAMA_SLAVE
 211                 /*
 212                  * A DAMA slave is _required_ to work as normal AX.25L2V2
 213                  * if no DAMA master is available.
 214                  */
 215                 case AX25_PROTO_DAMA_SLAVE:
 216                         if (!ax25->ax25_dev->dama.slave) ax25_kick(ax25);
 217                         break;
 218 #endif
 219         }
 220 }
 221
 222 /*
 223  *  This procedure is passed a buffer descriptor for an iframe. It builds
 224  *  the rest of the control part of the frame and then writes it out.
 225  */
 226 static void ax25_send_iframe(ax25_cb *ax25, struct sk_buff *skb, int poll_bit)
 227 {
 228         unsigned char *frame;
 229
 230         if (skb == NULL)
 231                 return;
 232
 233         skb->nh.raw = skb->data;
 234
 235         if (ax25->modulus == AX25_MODULUS) {
 236                 frame = skb_push(skb, 1);
 237
 238                 *frame = AX25_I;
 239                 *frame |= (poll_bit) ? AX25_PF : 0;
 240                 *frame |= (ax25->vr << 5);
 241                 *frame |= (ax25->vs << 1);
 242         } else {
 243                 frame = skb_push(skb, 2);
 244
 245                 frame[0] = AX25_I;
 246                 frame[0] |= (ax25->vs << 1);
 247                 frame[1] = (poll_bit) ? AX25_EPF : 0;
 248                 frame[1] |= (ax25->vr << 1);
 249         }
 250
 251         ax25_start_idletimer(ax25);
 252
 253         ax25_transmit_buffer(ax25, skb, AX25_COMMAND);
 254 }
 255
 256 void ax25_kick(ax25_cb *ax25)
 257 {
 258         struct sk_buff *skb, *skbn;
 259         int last = 1;
 260         unsigned short start, end, next;
 261
 262         if (ax25->state != AX25_STATE_3 && ax25->state != AX25_STATE_4)
 263                 return;
 264
 265         if (ax25->condition & AX25_COND_PEER_RX_BUSY)
 266                 return;
 267
 268         if (skb_peek(&ax25->write_queue) == NULL)
 269                 return;
 270
 271         start = (skb_peek(&ax25->ack_queue) == NULL) ? ax25->va : ax25->vs;
 272         end   = (ax25->va + ax25->window) % ax25->modulus;
 273
 274         if (start == end)
 275                 return;
 276
 277         ax25->vs = start;
 278
 279         /*
 280          * Transmit data until either we're out of data to send or
 281          * the window is full. Send a poll on the final I frame if
 282          * the window is filled.
 283          */
 284
 285         /*
 286          * Dequeue the frame and copy it.
 287          */
 288         skb  = skb_dequeue(&ax25->write_queue);
 289
 290         do {
 291                 if ((skbn = skb_clone(skb, GFP_ATOMIC)) == NULL) {
 292                         skb_queue_head(&ax25->write_queue, skb);
 293                         break;
 294                 }
 295
 296                 if (skb->sk != NULL)
 297                         skb_set_owner_w(skbn, skb->sk);
 298
 299                 next = (ax25->vs + 1) % ax25->modulus;
 300                 last = (next == end);
 301
 302                 /*
 303                  * Transmit the frame copy.
 304                  * bke 960114: do not set the Poll bit on the last frame
 305                  * in DAMA mode.
 306                  */
 307                 switch (ax25->ax25_dev->values[AX25_VALUES_PROTOCOL]) {
 308                         case AX25_PROTO_STD_SIMPLEX:
 309                         case AX25_PROTO_STD_DUPLEX:
 310                                 ax25_send_iframe(ax25, skbn, (last) ? AX25_POLLON : AX25_POLLOFF);
 311                                 break;
 312
 313 #ifdef CONFIG_AX25_DAMA_SLAVE
 314                         case AX25_PROTO_DAMA_SLAVE:
 315                                 ax25_send_iframe(ax25, skbn, AX25_POLLOFF);
 316                                 break;
 317 #endif
 318                 }
 319
 320                 ax25->vs = next;
 321
 322                 /*
 323                  * Requeue the original data frame.
 324                  */
 325                 skb_queue_tail(&ax25->ack_queue, skb);
 326
 327         } while (!last && (skb = skb_dequeue(&ax25->write_queue)) != NULL);
 328
 329         ax25->condition &= ~AX25_COND_ACK_PENDING;
 330
 331         if (!ax25_t1timer_running(ax25)) {
 332                 ax25_stop_t3timer(ax25);
 333                 ax25_calculate_t1(ax25);
 334                 ax25_start_t1timer(ax25);
 335         }
 336 }
 337
 338 void ax25_transmit_buffer(ax25_cb *ax25, struct sk_buff *skb, int type)
 339 {
 340         struct sk_buff *skbn;
 341         unsigned char *ptr;
 342         int headroom;
 343
 344         if (ax25->ax25_dev == NULL) {
 345                 ax25_disconnect(ax25, ENETUNREACH);
 346                 return;
 347         }
 348
 349         headroom = ax25_addr_size(ax25->digipeat);
 350
 351         if (skb_headroom(skb) < headroom) {
 352                 if ((skbn = skb_realloc_headroom(skb, headroom)) == NULL) {
 353                         printk(KERN_CRIT "AX.25: ax25_transmit_buffer - out of memory\n");
 354                         kfree_skb(skb);
 355                         return;
 356                 }
 357
 358                 if (skb->sk != NULL)
 359                         skb_set_owner_w(skbn, skb->sk);
 360
 361                 kfree_skb(skb);
 362                 skb = skbn;
 363         }
 364
 365         ptr = skb_push(skb, headroom);
 366
 367         ax25_addr_build(ptr, &ax25->source_addr, &ax25->dest_addr, ax25->digipeat, type, ax25->modulus);
 368
 369         skb->dev = ax25->ax25_dev->dev;
 370
 371         ax25_queue_xmit(skb);
 372 }
 373
 374 /*
 375  *      A small shim to dev_queue_xmit to add the KISS control byte, and do
 376  *      any packet forwarding in operation.
 377  */
 378 void ax25_queue_xmit(struct sk_buff *skb)
 379 {
 380         unsigned char *ptr;
 381
 382         skb->protocol = htons(ETH_P_AX25);
 383         skb->dev      = ax25_fwd_dev(skb->dev);
 384
 385         ptr  = skb_push(skb, 1);
 386         *ptr = 0x00;                    /* KISS */
 387
 388         dev_queue_xmit(skb);
 389 }
 390
 391 int ax25_check_iframes_acked(ax25_cb *ax25, unsigned short nr)
 392 {
 393         if (ax25->vs == nr) {
 394                 ax25_frames_acked(ax25, nr);
 395                 ax25_calculate_rtt(ax25);
 396                 ax25_stop_t1timer(ax25);
 397                 ax25_start_t3timer(ax25);
 398                 return 1;
 399         } else {
 400                 if (ax25->va != nr) {
 401                         ax25_frames_acked(ax25, nr);
 402                         ax25_calculate_t1(ax25);
 403                         ax25_start_t1timer(ax25);
 404                         return 1;
 405                 }
 406         }
 407         return 0;
 408 }
 409
 410 #endif