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         ax25_cb_add(ax25);
  96
  97         ax25->state = AX25_STATE_1;
  98
  99         ax25_start_heartbeat(ax25);
 100
 101         ax25_output(ax25, paclen, skb);
 102
 103         return ax25;                    /* We had to create it */
 104 }
 105
 106 EXPORT_SYMBOL(ax25_send_frame);
 107
 108 /*
 109  *      All outgoing AX.25 I frames pass via this routine. Therefore this is
 110  *      where the fragmentation of frames takes place. If fragment is set to
 111  *      zero then we are not allowed to do fragmentation, even if the frame
 112  *      is too large.
 113  */
 114 void ax25_output(ax25_cb *ax25, int paclen, struct sk_buff *skb)
 115 {
 116         struct sk_buff *skbn;
 117         unsigned char *p;
 118         int frontlen, len, fragno, ka9qfrag, first = 1;
 119
 120         if ((skb->len - 1) > paclen) {
 121                 if (*skb->data == AX25_P_TEXT) {
 122                         skb_pull(skb, 1); /* skip PID */
 123                         ka9qfrag = 0;
 124                 } else {
 125                         paclen -= 2;    /* Allow for fragment control info */
 126                         ka9qfrag = 1;
 127                 }
 128
 129                 fragno = skb->len / paclen;
 130                 if (skb->len % paclen == 0) fragno--;
 131
 132                 frontlen = skb_headroom(skb);   /* Address space + CTRL */
 133
 134                 while (skb->len > 0) {
 135                         spin_lock_bh(&ax25_frag_lock);
 136                         if ((skbn = alloc_skb(paclen + 2 + frontlen, GFP_ATOMIC)) == NULL) {
 137                                 spin_unlock_bh(&ax25_frag_lock);
 138                                 printk(KERN_CRIT "AX.25: ax25_output - out of memory\n");
 139                                 return;
 140                         }
 141
 142                         if (skb->sk != NULL)
 143                                 skb_set_owner_w(skbn, skb->sk);
 144
 145                         spin_unlock_bh(&ax25_frag_lock);
 146
 147                         len = (paclen > skb->len) ? skb->len : paclen;
 148
 149                         if (ka9qfrag == 1) {
 150                                 skb_reserve(skbn, frontlen + 2);
 151                                 skbn->nh.raw = skbn->data + (skb->nh.raw - skb->data);
 152                                 memcpy(skb_put(skbn, len), skb->data, len);
 153                                 p = skb_push(skbn, 2);
 154
 155                                 *p++ = AX25_P_SEGMENT;
 156
 157                                 *p = fragno--;
 158                                 if (first) {
 159                                         *p |= AX25_SEG_FIRST;
 160                                         first = 0;
 161                                 }
 162                         } else {
 163                                 skb_reserve(skbn, frontlen + 1);
 164                                 skbn->nh.raw = skbn->data + (skb->nh.raw - skb->data);
 165                                 memcpy(skb_put(skbn, len), skb->data, len);
 166                                 p = skb_push(skbn, 1);
 167                                 *p = AX25_P_TEXT;
 168                         }
 169
 170                         skb_pull(skb, len);
 171                         skb_queue_tail(&ax25->write_queue, skbn); /* Throw it on the queue */
 172                 }
 173
 174                 kfree_skb(skb);
 175         } else {
 176                 skb_queue_tail(&ax25->write_queue, skb);          /* Throw it on the queue */
 177         }
 178
 179         switch (ax25->ax25_dev->values[AX25_VALUES_PROTOCOL]) {
 180         case AX25_PROTO_STD_SIMPLEX:
 181         case AX25_PROTO_STD_DUPLEX:
 182                 ax25_kick(ax25);
 183                 break;
 184
 185 #ifdef CONFIG_AX25_DAMA_SLAVE
 186         /*
 187          * A DAMA slave is _required_ to work as normal AX.25L2V2
 188          * if no DAMA master is available.
 189          */
 190         case AX25_PROTO_DAMA_SLAVE:
 191                 if (!ax25->ax25_dev->dama.slave) ax25_kick(ax25);
 192                 break;
 193 #endif
 194         }
 195 }
 196
 197 /*
 198  *  This procedure is passed a buffer descriptor for an iframe. It builds
 199  *  the rest of the control part of the frame and then writes it out.
 200  */
 201 static void ax25_send_iframe(ax25_cb *ax25, struct sk_buff *skb, int poll_bit)
 202 {
 203         unsigned char *frame;
 204
 205         if (skb == NULL)
 206                 return;
 207
 208         skb->nh.raw = skb->data;
 209
 210         if (ax25->modulus == AX25_MODULUS) {
 211                 frame = skb_push(skb, 1);
 212
 213                 *frame = AX25_I;
 214                 *frame |= (poll_bit) ? AX25_PF : 0;
 215                 *frame |= (ax25->vr << 5);
 216                 *frame |= (ax25->vs << 1);
 217         } else {
 218                 frame = skb_push(skb, 2);
 219
 220                 frame[0] = AX25_I;
 221                 frame[0] |= (ax25->vs << 1);
 222                 frame[1] = (poll_bit) ? AX25_EPF : 0;
 223                 frame[1] |= (ax25->vr << 1);
 224         }
 225
 226         ax25_start_idletimer(ax25);
 227
 228         ax25_transmit_buffer(ax25, skb, AX25_COMMAND);
 229 }
 230
 231 void ax25_kick(ax25_cb *ax25)
 232 {
 233         struct sk_buff *skb, *skbn;
 234         int last = 1;
 235         unsigned short start, end, next;
 236
 237         if (ax25->state != AX25_STATE_3 && ax25->state != AX25_STATE_4)
 238                 return;
 239
 240         if (ax25->condition & AX25_COND_PEER_RX_BUSY)
 241                 return;
 242
 243         if (skb_peek(&ax25->write_queue) == NULL)
 244                 return;
 245
 246         start = (skb_peek(&ax25->ack_queue) == NULL) ? ax25->va : ax25->vs;
 247         end   = (ax25->va + ax25->window) % ax25->modulus;
 248
 249         if (start == end)
 250                 return;
 251
 252         ax25->vs = start;
 253
 254         /*
 255          * Transmit data until either we're out of data to send or
 256          * the window is full. Send a poll on the final I frame if
 257          * the window is filled.
 258          */
 259
 260         /*
 261          * Dequeue the frame and copy it.
 262          */
 263         skb  = skb_dequeue(&ax25->write_queue);
 264
 265         do {
 266                 if ((skbn = skb_clone(skb, GFP_ATOMIC)) == NULL) {
 267                         skb_queue_head(&ax25->write_queue, skb);
 268                         break;
 269                 }
 270
 271                 if (skb->sk != NULL)
 272                         skb_set_owner_w(skbn, skb->sk);
 273
 274                 next = (ax25->vs + 1) % ax25->modulus;
 275                 last = (next == end);
 276
 277                 /*
 278                  * Transmit the frame copy.
 279                  * bke 960114: do not set the Poll bit on the last frame
 280                  * in DAMA mode.
 281                  */
 282                 switch (ax25->ax25_dev->values[AX25_VALUES_PROTOCOL]) {
 283                 case AX25_PROTO_STD_SIMPLEX:
 284                 case AX25_PROTO_STD_DUPLEX:
 285                         ax25_send_iframe(ax25, skbn, (last) ? AX25_POLLON : AX25_POLLOFF);
 286                         break;
 287
 288 #ifdef CONFIG_AX25_DAMA_SLAVE
 289                 case AX25_PROTO_DAMA_SLAVE:
 290                         ax25_send_iframe(ax25, skbn, AX25_POLLOFF);
 291                         break;
 292 #endif
 293                 }
 294
 295                 ax25->vs = next;
 296
 297                 /*
 298                  * Requeue the original data frame.
 299                  */
 300                 skb_queue_tail(&ax25->ack_queue, skb);
 301
 302         } while (!last && (skb = skb_dequeue(&ax25->write_queue)) != NULL);
 303
 304         ax25->condition &= ~AX25_COND_ACK_PENDING;
 305
 306         if (!ax25_t1timer_running(ax25)) {
 307                 ax25_stop_t3timer(ax25);
 308                 ax25_calculate_t1(ax25);
 309                 ax25_start_t1timer(ax25);
 310         }
 311 }
 312
 313 void ax25_transmit_buffer(ax25_cb *ax25, struct sk_buff *skb, int type)
 314 {
 315         struct sk_buff *skbn;
 316         unsigned char *ptr;
 317         int headroom;
 318
 319         if (ax25->ax25_dev == NULL) {
 320                 ax25_disconnect(ax25, ENETUNREACH);
 321                 return;
 322         }
 323
 324         headroom = ax25_addr_size(ax25->digipeat);
 325
 326         if (skb_headroom(skb) < headroom) {
 327                 if ((skbn = skb_realloc_headroom(skb, headroom)) == NULL) {
 328                         printk(KERN_CRIT "AX.25: ax25_transmit_buffer - out of memory\n");
 329                         kfree_skb(skb);
 330                         return;
 331                 }
 332
 333                 if (skb->sk != NULL)
 334                         skb_set_owner_w(skbn, skb->sk);
 335
 336                 kfree_skb(skb);
 337                 skb = skbn;
 338         }
 339
 340         ptr = skb_push(skb, headroom);
 341
 342         ax25_addr_build(ptr, &ax25->source_addr, &ax25->dest_addr, ax25->digipeat, type, ax25->modulus);
 343
 344         ax25_queue_xmit(skb, ax25->ax25_dev->dev);
 345 }
 346
 347 /*
 348  *      A small shim to dev_queue_xmit to add the KISS control byte, and do
 349  *      any packet forwarding in operation.
 350  */
 351 void ax25_queue_xmit(struct sk_buff *skb, struct net_device *dev)
 352 {
 353         unsigned char *ptr;
 354
 355         skb->protocol = ax25_type_trans(skb, ax25_fwd_dev(dev));
 356
 357         ptr  = skb_push(skb, 1);
 358         *ptr = 0x00;                    /* KISS */
 359
 360         dev_queue_xmit(skb);
 361 }
 362
 363 int ax25_check_iframes_acked(ax25_cb *ax25, unsigned short nr)
 364 {
 365         if (ax25->vs == nr) {
 366                 ax25_frames_acked(ax25, nr);
 367                 ax25_calculate_rtt(ax25);
 368                 ax25_stop_t1timer(ax25);
 369                 ax25_start_t3timer(ax25);
 370                 return 1;
 371         } else {
 372                 if (ax25->va != nr) {
 373                         ax25_frames_acked(ax25, nr);
 374                         ax25_calculate_t1(ax25);
 375                         ax25_start_t1timer(ax25);
 376                         return 1;
 377                 }
 378         }
 379         return 0;
 380 }
 381