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/config.h>
  12 #include <linux/errno.h>
  13 #include <linux/types.h>
  14 #include <linux/socket.h>
  15 #include <linux/in.h>
  16 #include <linux/kernel.h>
  17 #include <linux/sched.h>
  18 #include <linux/timer.h>
  19 #include <linux/string.h>
  20 #include <linux/sockios.h>
  21 #include <linux/spinlock.h>
  22 #include <linux/net.h>
  23 #include <net/ax25.h>
  24 #include <linux/inet.h>
  25 #include <linux/netdevice.h>
  26 #include <linux/skbuff.h>
  27 #include <linux/netfilter.h>
  28 #include <net/sock.h>
  29 #include <asm/uaccess.h>
  30 #include <asm/system.h>
  31 #include <linux/fcntl.h>
  32 #include <linux/mm.h>
  33 #include <linux/interrupt.h>
  34
  35 static DEFINE_SPINLOCK(ax25_frag_lock);
  36
  37 ax25_cb *ax25_send_frame(struct sk_buff *skb, int paclen, ax25_address *src, ax25_address *dest, ax25_digi *digi, struct net_device *dev)
  38 {
  39         ax25_dev *ax25_dev;
  40         ax25_cb *ax25;
  41
  42         /*
  43          * Take the default packet length for the device if zero is
  44          * specified.
  45          */
  46         if (paclen == 0) {
  47                 if ((ax25_dev = ax25_dev_ax25dev(dev)) == NULL)
  48                         return NULL;
  49
  50                 paclen = ax25_dev->values[AX25_VALUES_PACLEN];
  51         }
  52
  53         /*
  54          * Look for an existing connection.
  55          */
  56         if ((ax25 = ax25_find_cb(src, dest, digi, dev)) != NULL) {
  57                 ax25_output(ax25, paclen, skb);
  58                 return ax25;            /* It already existed */
  59         }
  60
  61         if ((ax25_dev = ax25_dev_ax25dev(dev)) == NULL)
  62                 return NULL;
  63
  64         if ((ax25 = ax25_create_cb()) == NULL)
  65                 return NULL;
  66
  67         ax25_fillin_cb(ax25, ax25_dev);
  68
  69         ax25->source_addr = *src;
  70         ax25->dest_addr   = *dest;
  71
  72         if (digi != NULL) {
  73                 if ((ax25->digipeat = kmalloc(sizeof(ax25_digi), GFP_ATOMIC)) == NULL) {
  74                         ax25_cb_put(ax25);
  75                         return NULL;
  76                 }
  77                 memcpy(ax25->digipeat, digi, sizeof(ax25_digi));
  78         }
  79
  80         switch (ax25->ax25_dev->values[AX25_VALUES_PROTOCOL]) {
  81         case AX25_PROTO_STD_SIMPLEX:
  82         case AX25_PROTO_STD_DUPLEX:
  83                 ax25_std_establish_data_link(ax25);
  84                 break;
  85
  86 #ifdef CONFIG_AX25_DAMA_SLAVE
  87         case AX25_PROTO_DAMA_SLAVE:
  88                 if (ax25_dev->dama.slave)
  89                         ax25_ds_establish_data_link(ax25);
  90                 else
  91                         ax25_std_establish_data_link(ax25);
  92                 break;
  93 #endif
  94         }
  95
  96         ax25_cb_add(ax25);
  97
  98         ax25->state = AX25_STATE_1;
  99
 100         ax25_start_heartbeat(ax25);
 101
 102         ax25_output(ax25, paclen, skb);
 103
 104         return ax25;                    /* We had to create it */
 105 }
 106
 107 /*
 108  *      All outgoing AX.25 I frames pass via this routine. Therefore this is
 109  *      where the fragmentation of frames takes place. If fragment is set to
 110  *      zero then we are not allowed to do fragmentation, even if the frame
 111  *      is too large.
 112  */
 113 void ax25_output(ax25_cb *ax25, int paclen, struct sk_buff *skb)
 114 {
 115         struct sk_buff *skbn;
 116         unsigned char *p;
 117         int frontlen, len, fragno, ka9qfrag, first = 1;
 118
 119         if ((skb->len - 1) > paclen) {
 120                 if (*skb->data == AX25_P_TEXT) {
 121                         skb_pull(skb, 1); /* skip PID */
 122                         ka9qfrag = 0;
 123                 } else {
 124                         paclen -= 2;    /* Allow for fragment control info */
 125                         ka9qfrag = 1;
 126                 }
 127
 128                 fragno = skb->len / paclen;
 129                 if (skb->len % paclen == 0) fragno--;
 130
 131                 frontlen = skb_headroom(skb);   /* Address space + CTRL */
 132
 133                 while (skb->len > 0) {
 134                         spin_lock_bh(&ax25_frag_lock);
 135                         if ((skbn = alloc_skb(paclen + 2 + frontlen, GFP_ATOMIC)) == NULL) {
 136                                 spin_unlock_bh(&ax25_frag_lock);
 137                                 printk(KERN_CRIT "AX.25: ax25_output - out of memory\n");
 138                                 return;
 139                         }
 140
 141                         if (skb->sk != NULL)
 142                                 skb_set_owner_w(skbn, skb->sk);
 143
 144                         spin_unlock_bh(&ax25_frag_lock);
 145
 146                         len = (paclen > skb->len) ? skb->len : paclen;
 147
 148                         if (ka9qfrag == 1) {
 149                                 skb_reserve(skbn, frontlen + 2);
 150                                 skbn->nh.raw = skbn->data + (skb->nh.raw - skb->data);
 151                                 memcpy(skb_put(skbn, len), skb->data, len);
 152                                 p = skb_push(skbn, 2);
 153
 154                                 *p++ = AX25_P_SEGMENT;
 155
 156                                 *p = fragno--;
 157                                 if (first) {
 158                                         *p |= AX25_SEG_FIRST;
 159                                         first = 0;
 160                                 }
 161                         } else {
 162                                 skb_reserve(skbn, frontlen + 1);
 163                                 skbn->nh.raw = skbn->data + (skb->nh.raw - skb->data);
 164                                 memcpy(skb_put(skbn, len), skb->data, len);
 165                                 p = skb_push(skbn, 1);
 166                                 *p = AX25_P_TEXT;
 167                         }
 168
 169                         skb_pull(skb, len);
 170                         skb_queue_tail(&ax25->write_queue, skbn); /* Throw it on the queue */
 171                 }
 172
 173                 kfree_skb(skb);
 174         } else {
 175                 skb_queue_tail(&ax25->write_queue, skb);          /* Throw it on the queue */
 176         }
 177
 178         switch (ax25->ax25_dev->values[AX25_VALUES_PROTOCOL]) {
 179         case AX25_PROTO_STD_SIMPLEX:
 180         case AX25_PROTO_STD_DUPLEX:
 181                 ax25_kick(ax25);
 182                 break;
 183
 184 #ifdef CONFIG_AX25_DAMA_SLAVE
 185         /*
 186          * A DAMA slave is _required_ to work as normal AX.25L2V2
 187          * if no DAMA master is available.
 188          */
 189         case AX25_PROTO_DAMA_SLAVE:
 190                 if (!ax25->ax25_dev->dama.slave) ax25_kick(ax25);
 191                 break;
 192 #endif
 193         }
 194 }
 195
 196 /*
 197  *  This procedure is passed a buffer descriptor for an iframe. It builds
 198  *  the rest of the control part of the frame and then writes it out.
 199  */
 200 static void ax25_send_iframe(ax25_cb *ax25, struct sk_buff *skb, int poll_bit)
 201 {
 202         unsigned char *frame;
 203
 204         if (skb == NULL)
 205                 return;
 206
 207         skb->nh.raw = skb->data;
 208
 209         if (ax25->modulus == AX25_MODULUS) {
 210                 frame = skb_push(skb, 1);
 211
 212                 *frame = AX25_I;
 213                 *frame |= (poll_bit) ? AX25_PF : 0;
 214                 *frame |= (ax25->vr << 5);
 215                 *frame |= (ax25->vs << 1);
 216         } else {
 217                 frame = skb_push(skb, 2);
 218
 219                 frame[0] = AX25_I;
 220                 frame[0] |= (ax25->vs << 1);
 221                 frame[1] = (poll_bit) ? AX25_EPF : 0;
 222                 frame[1] |= (ax25->vr << 1);
 223         }
 224
 225         ax25_start_idletimer(ax25);
 226
 227         ax25_transmit_buffer(ax25, skb, AX25_COMMAND);
 228 }
 229
 230 void ax25_kick(ax25_cb *ax25)
 231 {
 232         struct sk_buff *skb, *skbn;
 233         int last = 1;
 234         unsigned short start, end, next;
 235
 236         if (ax25->state != AX25_STATE_3 && ax25->state != AX25_STATE_4)
 237                 return;
 238
 239         if (ax25->condition & AX25_COND_PEER_RX_BUSY)
 240                 return;
 241
 242         if (skb_peek(&ax25->write_queue) == NULL)
 243                 return;
 244
 245         start = (skb_peek(&ax25->ack_queue) == NULL) ? ax25->va : ax25->vs;
 246         end   = (ax25->va + ax25->window) % ax25->modulus;
 247
 248         if (start == end)
 249                 return;
 250
 251         ax25->vs = start;
 252
 253         /*
 254          * Transmit data until either we're out of data to send or
 255          * the window is full. Send a poll on the final I frame if
 256          * the window is filled.
 257          */
 258
 259         /*
 260          * Dequeue the frame and copy it.
 261          */
 262         skb  = skb_dequeue(&ax25->write_queue);
 263
 264         do {
 265                 if ((skbn = skb_clone(skb, GFP_ATOMIC)) == NULL) {
 266                         skb_queue_head(&ax25->write_queue, skb);
 267                         break;
 268                 }
 269
 270                 if (skb->sk != NULL)
 271                         skb_set_owner_w(skbn, skb->sk);
 272
 273                 next = (ax25->vs + 1) % ax25->modulus;
 274                 last = (next == end);
 275
 276                 /*
 277                  * Transmit the frame copy.
 278                  * bke 960114: do not set the Poll bit on the last frame
 279                  * in DAMA mode.
 280                  */
 281                 switch (ax25->ax25_dev->values[AX25_VALUES_PROTOCOL]) {
 282                 case AX25_PROTO_STD_SIMPLEX:
 283                 case AX25_PROTO_STD_DUPLEX:
 284                         ax25_send_iframe(ax25, skbn, (last) ? AX25_POLLON : AX25_POLLOFF);
 285                         break;
 286
 287 #ifdef CONFIG_AX25_DAMA_SLAVE
 288                 case AX25_PROTO_DAMA_SLAVE:
 289                         ax25_send_iframe(ax25, skbn, AX25_POLLOFF);
 290                         break;
 291 #endif
 292                 }
 293
 294                 ax25->vs = next;
 295
 296                 /*
 297                  * Requeue the original data frame.
 298                  */
 299                 skb_queue_tail(&ax25->ack_queue, skb);
 300
 301         } while (!last && (skb = skb_dequeue(&ax25->write_queue)) != NULL);
 302
 303         ax25->condition &= ~AX25_COND_ACK_PENDING;
 304
 305         if (!ax25_t1timer_running(ax25)) {
 306                 ax25_stop_t3timer(ax25);
 307                 ax25_calculate_t1(ax25);
 308                 ax25_start_t1timer(ax25);
 309         }
 310 }
 311
 312 void ax25_transmit_buffer(ax25_cb *ax25, struct sk_buff *skb, int type)
 313 {
 314         struct sk_buff *skbn;
 315         unsigned char *ptr;
 316         int headroom;
 317
 318         if (ax25->ax25_dev == NULL) {
 319                 ax25_disconnect(ax25, ENETUNREACH);
 320                 return;
 321         }
 322
 323         headroom = ax25_addr_size(ax25->digipeat);
 324
 325         if (skb_headroom(skb) < headroom) {
 326                 if ((skbn = skb_realloc_headroom(skb, headroom)) == NULL) {
 327                         printk(KERN_CRIT "AX.25: ax25_transmit_buffer - out of memory\n");
 328                         kfree_skb(skb);
 329                         return;
 330                 }
 331
 332                 if (skb->sk != NULL)
 333                         skb_set_owner_w(skbn, skb->sk);
 334
 335                 kfree_skb(skb);
 336                 skb = skbn;
 337         }
 338
 339         ptr = skb_push(skb, headroom);
 340
 341         ax25_addr_build(ptr, &ax25->source_addr, &ax25->dest_addr, ax25->digipeat, type, ax25->modulus);
 342
 343         skb->dev = ax25->ax25_dev->dev;
 344
 345         ax25_queue_xmit(skb);
 346 }
 347
 348 /*
 349  *      A small shim to dev_queue_xmit to add the KISS control byte, and do
 350  *      any packet forwarding in operation.
 351  */
 352 void ax25_queue_xmit(struct sk_buff *skb)
 353 {
 354         unsigned char *ptr;
 355
 356         skb->protocol = htons(ETH_P_AX25);
 357         skb->dev      = ax25_fwd_dev(skb->dev);
 358
 359         ptr  = skb_push(skb, 1);
 360         *ptr = 0x00;                    /* KISS */
 361
 362         dev_queue_xmit(skb);
 363 }
 364
 365 int ax25_check_iframes_acked(ax25_cb *ax25, unsigned short nr)
 366 {
 367         if (ax25->vs == nr) {
 368                 ax25_frames_acked(ax25, nr);
 369                 ax25_calculate_rtt(ax25);
 370                 ax25_stop_t1timer(ax25);
 371                 ax25_start_t3timer(ax25);
 372                 return 1;
 373         } else {
 374                 if (ax25->va != nr) {
 375                         ax25_frames_acked(ax25, nr);
 376                         ax25_calculate_t1(ax25);
 377                         ax25_start_t1timer(ax25);
 378                         return 1;
 379                 }
 380         }
 381         return 0;
 382 }
 383