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                                 skb_set_network_header(skbn,
 152                                                       skb_network_offset(skb));
 153                                 skb_copy_from_linear_data(skb, skb_put(skbn, len), len);
 154                                 p = skb_push(skbn, 2);
 155
 156                                 *p++ = AX25_P_SEGMENT;
 157
 158                                 *p = fragno--;
 159                                 if (first) {
 160                                         *p |= AX25_SEG_FIRST;
 161                                         first = 0;
 162                                 }
 163                         } else {
 164                                 skb_reserve(skbn, frontlen + 1);
 165                                 skb_set_network_header(skbn,
 166                                                       skb_network_offset(skb));
 167                                 skb_copy_from_linear_data(skb, skb_put(skbn, len), len);
 168                                 p = skb_push(skbn, 1);
 169                                 *p = AX25_P_TEXT;
 170                         }
 171
 172                         skb_pull(skb, len);
 173                         skb_queue_tail(&ax25->write_queue, skbn); /* Throw it on the queue */
 174                 }
 175
 176                 kfree_skb(skb);
 177         } else {
 178                 skb_queue_tail(&ax25->write_queue, skb);          /* Throw it on the queue */
 179         }
 180
 181         switch (ax25->ax25_dev->values[AX25_VALUES_PROTOCOL]) {
 182         case AX25_PROTO_STD_SIMPLEX:
 183         case AX25_PROTO_STD_DUPLEX:
 184                 ax25_kick(ax25);
 185                 break;
 186
 187 #ifdef CONFIG_AX25_DAMA_SLAVE
 188         /*
 189          * A DAMA slave is _required_ to work as normal AX.25L2V2
 190          * if no DAMA master is available.
 191          */
 192         case AX25_PROTO_DAMA_SLAVE:
 193                 if (!ax25->ax25_dev->dama.slave) ax25_kick(ax25);
 194                 break;
 195 #endif
 196         }
 197 }
 198
 199 /*
 200  *  This procedure is passed a buffer descriptor for an iframe. It builds
 201  *  the rest of the control part of the frame and then writes it out.
 202  */
 203 static void ax25_send_iframe(ax25_cb *ax25, struct sk_buff *skb, int poll_bit)
 204 {
 205         unsigned char *frame;
 206
 207         if (skb == NULL)
 208                 return;
 209
 210         skb_reset_network_header(skb);
 211
 212         if (ax25->modulus == AX25_MODULUS) {
 213                 frame = skb_push(skb, 1);
 214
 215                 *frame = AX25_I;
 216                 *frame |= (poll_bit) ? AX25_PF : 0;
 217                 *frame |= (ax25->vr << 5);
 218                 *frame |= (ax25->vs << 1);
 219         } else {
 220                 frame = skb_push(skb, 2);
 221
 222                 frame[0] = AX25_I;
 223                 frame[0] |= (ax25->vs << 1);
 224                 frame[1] = (poll_bit) ? AX25_EPF : 0;
 225                 frame[1] |= (ax25->vr << 1);
 226         }
 227
 228         ax25_start_idletimer(ax25);
 229
 230         ax25_transmit_buffer(ax25, skb, AX25_COMMAND);
 231 }
 232
 233 void ax25_kick(ax25_cb *ax25)
 234 {
 235         struct sk_buff *skb, *skbn;
 236         int last = 1;
 237         unsigned short start, end, next;
 238
 239         if (ax25->state != AX25_STATE_3 && ax25->state != AX25_STATE_4)
 240                 return;
 241
 242         if (ax25->condition & AX25_COND_PEER_RX_BUSY)
 243                 return;
 244
 245         if (skb_peek(&ax25->write_queue) == NULL)
 246                 return;
 247
 248         start = (skb_peek(&ax25->ack_queue) == NULL) ? ax25->va : ax25->vs;
 249         end   = (ax25->va + ax25->window) % ax25->modulus;
 250
 251         if (start == end)
 252                 return;
 253
 254         ax25->vs = start;
 255
 256         /*
 257          * Transmit data until either we're out of data to send or
 258          * the window is full. Send a poll on the final I frame if
 259          * the window is filled.
 260          */
 261
 262         /*
 263          * Dequeue the frame and copy it.
 264          */
 265         skb  = skb_dequeue(&ax25->write_queue);
 266
 267         do {
 268                 if ((skbn = skb_clone(skb, GFP_ATOMIC)) == NULL) {
 269                         skb_queue_head(&ax25->write_queue, skb);
 270                         break;
 271                 }
 272
 273                 if (skb->sk != NULL)
 274                         skb_set_owner_w(skbn, skb->sk);
 275
 276                 next = (ax25->vs + 1) % ax25->modulus;
 277                 last = (next == end);
 278
 279                 /*
 280                  * Transmit the frame copy.
 281                  * bke 960114: do not set the Poll bit on the last frame
 282                  * in DAMA mode.
 283                  */
 284                 switch (ax25->ax25_dev->values[AX25_VALUES_PROTOCOL]) {
 285                 case AX25_PROTO_STD_SIMPLEX:
 286                 case AX25_PROTO_STD_DUPLEX:
 287                         ax25_send_iframe(ax25, skbn, (last) ? AX25_POLLON : AX25_POLLOFF);
 288                         break;
 289
 290 #ifdef CONFIG_AX25_DAMA_SLAVE
 291                 case AX25_PROTO_DAMA_SLAVE:
 292                         ax25_send_iframe(ax25, skbn, AX25_POLLOFF);
 293                         break;
 294 #endif
 295                 }
 296
 297                 ax25->vs = next;
 298
 299                 /*
 300                  * Requeue the original data frame.
 301                  */
 302                 skb_queue_tail(&ax25->ack_queue, skb);
 303
 304         } while (!last && (skb = skb_dequeue(&ax25->write_queue)) != NULL);
 305
 306         ax25->condition &= ~AX25_COND_ACK_PENDING;
 307
 308         if (!ax25_t1timer_running(ax25)) {
 309                 ax25_stop_t3timer(ax25);
 310                 ax25_calculate_t1(ax25);
 311                 ax25_start_t1timer(ax25);
 312         }
 313 }
 314
 315 void ax25_transmit_buffer(ax25_cb *ax25, struct sk_buff *skb, int type)
 316 {
 317         struct sk_buff *skbn;
 318         unsigned char *ptr;
 319         int headroom;
 320
 321         if (ax25->ax25_dev == NULL) {
 322                 ax25_disconnect(ax25, ENETUNREACH);
 323                 return;
 324         }
 325
 326         headroom = ax25_addr_size(ax25->digipeat);
 327
 328         if (skb_headroom(skb) < headroom) {
 329                 if ((skbn = skb_realloc_headroom(skb, headroom)) == NULL) {
 330                         printk(KERN_CRIT "AX.25: ax25_transmit_buffer - out of memory\n");
 331                         kfree_skb(skb);
 332                         return;
 333                 }
 334
 335                 if (skb->sk != NULL)
 336                         skb_set_owner_w(skbn, skb->sk);
 337
 338                 kfree_skb(skb);
 339                 skb = skbn;
 340         }
 341
 342         ptr = skb_push(skb, headroom);
 343
 344         ax25_addr_build(ptr, &ax25->source_addr, &ax25->dest_addr, ax25->digipeat, type, ax25->modulus);
 345
 346         ax25_queue_xmit(skb, ax25->ax25_dev->dev);
 347 }
 348
 349 /*
 350  *      A small shim to dev_queue_xmit to add the KISS control byte, and do
 351  *      any packet forwarding in operation.
 352  */
 353 void ax25_queue_xmit(struct sk_buff *skb, struct net_device *dev)
 354 {
 355         unsigned char *ptr;
 356
 357         skb->protocol = ax25_type_trans(skb, ax25_fwd_dev(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