net/ax25/ax25_out.c

   1 /*
   2  * This program is free software; you can redistribute it and/or modify
   3  * it under the terms of the GNU General Public License as published by
   4  * the Free Software Foundation; either version 2 of the License, or
   5  * (at your option) any later version.
   6  *
   7  * Copyright (C) Alan Cox GW4PTS (alan@lxorguk.ukuu.org.uk)
   8  * Copyright (C) Jonathan Naylor G4KLX (g4klx@g4klx.demon.co.uk)
   9  * Copyright (C) Joerg Reuter DL1BKE (jreuter@yaina.de)
  10  */
  11 #include <linux/errno.h>
  12 #include <linux/types.h>
  13 #include <linux/socket.h>
  14 #include <linux/in.h>
  15 #include <linux/kernel.h>
  16 #include <linux/module.h>
  17 #include <linux/timer.h>
  18 #include <linux/string.h>
  19 #include <linux/sockios.h>
  20 #include <linux/spinlock.h>
  21 #include <linux/net.h>
  22 #include <net/ax25.h>
  23 #include <linux/inet.h>
  24 #include <linux/netdevice.h>
  25 #include <linux/skbuff.h>
  26 #include <linux/netfilter.h>
  27 #include <net/sock.h>
  28 #include <asm/uaccess.h>
  29 #include <asm/system.h>
  30 #include <linux/fcntl.h>
  31 #include <linux/mm.h>
  32 #include <linux/interrupt.h>
  33
  34 static DEFINE_SPINLOCK(ax25_frag_lock);
  35
  36 ax25_cb *ax25_send_frame(struct sk_buff *skb, int paclen, ax25_address *src, ax25_address *dest, ax25_digi *digi, struct net_device *dev)
  37 {
  38         ax25_dev *ax25_dev;
  39         ax25_cb *ax25;
  40
  41         /*
  42          * Take the default packet length for the device if zero is
  43          * specified.
  44          */
  45         if (paclen == 0) {
  46                 if ((ax25_dev = ax25_dev_ax25dev(dev)) == NULL)
  47                         return NULL;
  48
  49                 paclen = ax25_dev->values[AX25_VALUES_PACLEN];
  50         }
  51
  52         /*
  53          * Look for an existing connection.
  54          */
  55         if ((ax25 = ax25_find_cb(src, dest, digi, dev)) != NULL) {
  56                 ax25_output(ax25, paclen, skb);
  57                 return ax25;            /* It already existed */
  58         }
  59
  60         if ((ax25_dev = ax25_dev_ax25dev(dev)) == NULL)
  61                 return NULL;
  62
  63         if ((ax25 = ax25_create_cb()) == NULL)
  64                 return NULL;
  65
  66         ax25_fillin_cb(ax25, ax25_dev);
  67
  68         ax25->source_addr = *src;
  69         ax25->dest_addr   = *dest;
  70
  71         if (digi != NULL) {
  72                 ax25->digipeat = kmemdup(digi, sizeof(*digi), GFP_ATOMIC);
  73                 if (ax25->digipeat == NULL) {
  74                         ax25_cb_put(ax25);
  75                         return NULL;
  76                 }
  77         }
  78
  79         switch (ax25->ax25_dev->values[AX25_VALUES_PROTOCOL]) {
  80         case AX25_PROTO_STD_SIMPLEX:
  81         case AX25_PROTO_STD_DUPLEX:
  82                 ax25_std_establish_data_link(ax25);
  83                 break;
  84
  85 #ifdef CONFIG_AX25_DAMA_SLAVE
  86         case AX25_PROTO_DAMA_SLAVE:
  87                 if (ax25_dev->dama.slave)
  88                         ax25_ds_establish_data_link(ax25);
  89                 else
  90                         ax25_std_establish_data_link(ax25);
  91                 break;
  92 #endif
  93         }
  94
  95         /*
  96          * There is one ref for the state machine; a caller needs
  97          * one more to put it back, just like with the existing one.
  98          */
  99         ax25_cb_hold(ax25);
 100
 101         ax25_cb_add(ax25);
 102
 103         ax25->state = AX25_STATE_1;
 104
 105         ax25_start_heartbeat(ax25);
 106
 107         ax25_output(ax25, paclen, skb);
 108
 109         return ax25;                    /* We had to create it */
 110 }
 111
 112 EXPORT_SYMBOL(ax25_send_frame);
 113
 114 /*
 115  *      All outgoing AX.25 I frames pass via this routine. Therefore this is
 116  *      where the fragmentation of frames takes place. If fragment is set to
 117  *      zero then we are not allowed to do fragmentation, even if the frame
 118  *      is too large.
 119  */
 120 void ax25_output(ax25_cb *ax25, int paclen, struct sk_buff *skb)
 121 {
 122         struct sk_buff *skbn;
 123         unsigned char *p;
 124         int frontlen, len, fragno, ka9qfrag, first = 1;
 125
 126         if (paclen < 16) {
 127                 WARN_ON_ONCE(1);
 128                 kfree_skb(skb);
 129                 return;
 130         }
 131
 132         if ((skb->len - 1) > paclen) {
 133                 if (*skb->data == AX25_P_TEXT) {
 134                         skb_pull(skb, 1); /* skip PID */
 135                         ka9qfrag = 0;
 136                 } else {
 137                         paclen -= 2;    /* Allow for fragment control info */
 138                         ka9qfrag = 1;
 139                 }
 140
 141                 fragno = skb->len / paclen;
 142                 if (skb->len % paclen == 0) fragno--;
 143
 144                 frontlen = skb_headroom(skb);   /* Address space + CTRL */
 145
 146                 while (skb->len > 0) {
 147                         spin_lock_bh(&ax25_frag_lock);
 148                         if ((skbn = alloc_skb(paclen + 2 + frontlen, GFP_ATOMIC)) == NULL) {
 149                                 spin_unlock_bh(&ax25_frag_lock);
 150                                 printk(KERN_CRIT "AX.25: ax25_output - out of memory\n");
 151                                 return;
 152                         }
 153
 154                         if (skb->sk != NULL)
 155                                 skb_set_owner_w(skbn, skb->sk);
 156
 157                         spin_unlock_bh(&ax25_frag_lock);
 158
 159                         len = (paclen > skb->len) ? skb->len : paclen;
 160
 161                         if (ka9qfrag == 1) {
 162                                 skb_reserve(skbn, frontlen + 2);
 163                                 skb_set_network_header(skbn,
 164                                                       skb_network_offset(skb));
 165                                 skb_copy_from_linear_data(skb, skb_put(skbn, len), len);
 166                                 p = skb_push(skbn, 2);
 167
 168                                 *p++ = AX25_P_SEGMENT;
 169
 170                                 *p = fragno--;
 171                                 if (first) {
 172                                         *p |= AX25_SEG_FIRST;
 173                                         first = 0;
 174                                 }
 175                         } else {
 176                                 skb_reserve(skbn, frontlen + 1);
 177                                 skb_set_network_header(skbn,
 178                                                       skb_network_offset(skb));
 179                                 skb_copy_from_linear_data(skb, skb_put(skbn, len), len);
 180                                 p = skb_push(skbn, 1);
 181                                 *p = AX25_P_TEXT;
 182                         }
 183
 184                         skb_pull(skb, len);
 185                         skb_queue_tail(&ax25->write_queue, skbn); /* Throw it on the queue */
 186                 }
 187
 188                 kfree_skb(skb);
 189         } else {
 190                 skb_queue_tail(&ax25->write_queue, skb);          /* Throw it on the queue */
 191         }
 192
 193         switch (ax25->ax25_dev->values[AX25_VALUES_PROTOCOL]) {
 194         case AX25_PROTO_STD_SIMPLEX:
 195         case AX25_PROTO_STD_DUPLEX:
 196                 ax25_kick(ax25);
 197                 break;
 198
 199 #ifdef CONFIG_AX25_DAMA_SLAVE
 200         /*
 201          * A DAMA slave is _required_ to work as normal AX.25L2V2
 202          * if no DAMA master is available.
 203          */
 204         case AX25_PROTO_DAMA_SLAVE:
 205                 if (!ax25->ax25_dev->dama.slave) ax25_kick(ax25);
 206                 break;
 207 #endif
 208         }
 209 }
 210
 211 /*
 212  *  This procedure is passed a buffer descriptor for an iframe. It builds
 213  *  the rest of the control part of the frame and then writes it out.
 214  */
 215 static void ax25_send_iframe(ax25_cb *ax25, struct sk_buff *skb, int poll_bit)
 216 {
 217         unsigned char *frame;
 218
 219         if (skb == NULL)
 220                 return;
 221
 222         skb_reset_network_header(skb);
 223
 224         if (ax25->modulus == AX25_MODULUS) {
 225                 frame = skb_push(skb, 1);
 226
 227                 *frame = AX25_I;
 228                 *frame |= (poll_bit) ? AX25_PF : 0;
 229                 *frame |= (ax25->vr << 5);
 230                 *frame |= (ax25->vs << 1);
 231         } else {
 232                 frame = skb_push(skb, 2);
 233
 234                 frame[0] = AX25_I;
 235                 frame[0] |= (ax25->vs << 1);
 236                 frame[1] = (poll_bit) ? AX25_EPF : 0;
 237                 frame[1] |= (ax25->vr << 1);
 238         }
 239
 240         ax25_start_idletimer(ax25);
 241
 242         ax25_transmit_buffer(ax25, skb, AX25_COMMAND);
 243 }
 244
 245 void ax25_kick(ax25_cb *ax25)
 246 {
 247         struct sk_buff *skb, *skbn;
 248         int last = 1;
 249         unsigned short start, end, next;
 250
 251         if (ax25->state != AX25_STATE_3 && ax25->state != AX25_STATE_4)
 252                 return;
 253
 254         if (ax25->condition & AX25_COND_PEER_RX_BUSY)
 255                 return;
 256
 257         if (skb_peek(&ax25->write_queue) == NULL)
 258                 return;
 259
 260         start = (skb_peek(&ax25->ack_queue) == NULL) ? ax25->va : ax25->vs;
 261         end   = (ax25->va + ax25->window) % ax25->modulus;
 262
 263         if (start == end)
 264                 return;
 265
 266         /*
 267          * Transmit data until either we're out of data to send or
 268          * the window is full. Send a poll on the final I frame if
 269          * the window is filled.
 270          */
 271
 272         /*
 273          * Dequeue the frame and copy it.
 274          * Check for race with ax25_clear_queues().
 275          */
 276         skb  = skb_dequeue(&ax25->write_queue);
 277         if (!skb)
 278                 return;
 279
 280         ax25->vs = start;
 281
 282         do {
 283                 if ((skbn = skb_clone(skb, GFP_ATOMIC)) == NULL) {
 284                         skb_queue_head(&ax25->write_queue, skb);
 285                         break;
 286                 }
 287
 288                 if (skb->sk != NULL)
 289                         skb_set_owner_w(skbn, skb->sk);
 290
 291                 next = (ax25->vs + 1) % ax25->modulus;
 292                 last = (next == end);
 293
 294                 /*
 295                  * Transmit the frame copy.
 296                  * bke 960114: do not set the Poll bit on the last frame
 297                  * in DAMA mode.
 298                  */
 299                 switch (ax25->ax25_dev->values[AX25_VALUES_PROTOCOL]) {
 300                 case AX25_PROTO_STD_SIMPLEX:
 301                 case AX25_PROTO_STD_DUPLEX:
 302                         ax25_send_iframe(ax25, skbn, (last) ? AX25_POLLON : AX25_POLLOFF);
 303                         break;
 304
 305 #ifdef CONFIG_AX25_DAMA_SLAVE
 306                 case AX25_PROTO_DAMA_SLAVE:
 307                         ax25_send_iframe(ax25, skbn, AX25_POLLOFF);
 308                         break;
 309 #endif
 310                 }
 311
 312                 ax25->vs = next;
 313
 314                 /*
 315                  * Requeue the original data frame.
 316                  */
 317                 skb_queue_tail(&ax25->ack_queue, skb);
 318
 319         } while (!last && (skb = skb_dequeue(&ax25->write_queue)) != NULL);
 320
 321         ax25->condition &= ~AX25_COND_ACK_PENDING;
 322
 323         if (!ax25_t1timer_running(ax25)) {
 324                 ax25_stop_t3timer(ax25);
 325                 ax25_calculate_t1(ax25);
 326                 ax25_start_t1timer(ax25);
 327         }
 328 }
 329
 330 void ax25_transmit_buffer(ax25_cb *ax25, struct sk_buff *skb, int type)
 331 {
 332         struct sk_buff *skbn;
 333         unsigned char *ptr;
 334         int headroom;
 335
 336         if (ax25->ax25_dev == NULL) {
 337                 ax25_disconnect(ax25, ENETUNREACH);
 338                 return;
 339         }
 340
 341         headroom = ax25_addr_size(ax25->digipeat);
 342
 343         if (skb_headroom(skb) < headroom) {
 344                 if ((skbn = skb_realloc_headroom(skb, headroom)) == NULL) {
 345                         printk(KERN_CRIT "AX.25: ax25_transmit_buffer - out of memory\n");
 346                         kfree_skb(skb);
 347                         return;
 348                 }
 349
 350                 if (skb->sk != NULL)
 351                         skb_set_owner_w(skbn, skb->sk);
 352
 353                 kfree_skb(skb);
 354                 skb = skbn;
 355         }
 356
 357         ptr = skb_push(skb, headroom);
 358
 359         ax25_addr_build(ptr, &ax25->source_addr, &ax25->dest_addr, ax25->digipeat, type, ax25->modulus);
 360
 361         ax25_queue_xmit(skb, ax25->ax25_dev->dev);
 362 }
 363
 364 /*
 365  *      A small shim to dev_queue_xmit to add the KISS control byte, and do
 366  *      any packet forwarding in operation.
 367  */
 368 void ax25_queue_xmit(struct sk_buff *skb, struct net_device *dev)
 369 {
 370         unsigned char *ptr;
 371
 372         skb->protocol = ax25_type_trans(skb, ax25_fwd_dev(dev));
 373
 374         ptr  = skb_push(skb, 1);
 375         *ptr = 0x00;                    /* KISS */
 376
 377         dev_queue_xmit(skb);
 378 }
 379
 380 int ax25_check_iframes_acked(ax25_cb *ax25, unsigned short nr)
 381 {
 382         if (ax25->vs == nr) {
 383                 ax25_frames_acked(ax25, nr);
 384                 ax25_calculate_rtt(ax25);
 385                 ax25_stop_t1timer(ax25);
 386                 ax25_start_t3timer(ax25);
 387                 return 1;
 388         } else {
 389                 if (ax25->va != nr) {
 390                         ax25_frames_acked(ax25, nr);
 391                         ax25_calculate_t1(ax25);
 392                         ax25_start_t1timer(ax25);
 393                         return 1;
 394                 }
 395         }
 396         return 0;
 397 }
 398