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/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                 ax25->digipeat = kmemdup(digi, sizeof(*digi), GFP_ATOMIC);
  74                 if (ax25->digipeat == NULL) {
  75                         ax25_cb_put(ax25);
  76                         return NULL;
  77                 }
  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 EXPORT_SYMBOL(ax25_send_frame);
 108
 109 /*
 110  *      All outgoing AX.25 I frames pass via this routine. Therefore this is
 111  *      where the fragmentation of frames takes place. If fragment is set to
 112  *      zero then we are not allowed to do fragmentation, even if the frame
 113  *      is too large.
 114  */
 115 void ax25_output(ax25_cb *ax25, int paclen, struct sk_buff *skb)
 116 {
 117         struct sk_buff *skbn;
 118         unsigned char *p;
 119         int frontlen, len, fragno, ka9qfrag, first = 1;
 120
 121         if ((skb->len - 1) > paclen) {
 122                 if (*skb->data == AX25_P_TEXT) {
 123                         skb_pull(skb, 1); /* skip PID */
 124                         ka9qfrag = 0;
 125                 } else {
 126                         paclen -= 2;    /* Allow for fragment control info */
 127                         ka9qfrag = 1;
 128                 }
 129
 130                 fragno = skb->len / paclen;
 131                 if (skb->len % paclen == 0) fragno--;
 132
 133                 frontlen = skb_headroom(skb);   /* Address space + CTRL */
 134
 135                 while (skb->len > 0) {
 136                         spin_lock_bh(&ax25_frag_lock);
 137                         if ((skbn = alloc_skb(paclen + 2 + frontlen, GFP_ATOMIC)) == NULL) {
 138                                 spin_unlock_bh(&ax25_frag_lock);
 139                                 printk(KERN_CRIT "AX.25: ax25_output - out of memory\n");
 140                                 return;
 141                         }
 142
 143                         if (skb->sk != NULL)
 144                                 skb_set_owner_w(skbn, skb->sk);
 145
 146                         spin_unlock_bh(&ax25_frag_lock);
 147
 148                         len = (paclen > skb->len) ? skb->len : paclen;
 149
 150                         if (ka9qfrag == 1) {
 151                                 skb_reserve(skbn, frontlen + 2);
 152                                 skbn->nh.raw = skbn->data + (skb->nh.raw - skb->data);
 153                                 memcpy(skb_put(skbn, len), skb->data, 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                                 skbn->nh.raw = skbn->data + (skb->nh.raw - skb->data);
 166                                 memcpy(skb_put(skbn, len), skb->data, len);
 167                                 p = skb_push(skbn, 1);
 168                                 *p = AX25_P_TEXT;
 169                         }
 170
 171                         skb_pull(skb, len);
 172                         skb_queue_tail(&ax25->write_queue, skbn); /* Throw it on the queue */
 173                 }
 174
 175                 kfree_skb(skb);
 176         } else {
 177                 skb_queue_tail(&ax25->write_queue, skb);          /* Throw it on the queue */
 178         }
 179
 180         switch (ax25->ax25_dev->values[AX25_VALUES_PROTOCOL]) {
 181         case AX25_PROTO_STD_SIMPLEX:
 182         case AX25_PROTO_STD_DUPLEX:
 183                 ax25_kick(ax25);
 184                 break;
 185
 186 #ifdef CONFIG_AX25_DAMA_SLAVE
 187         /*
 188          * A DAMA slave is _required_ to work as normal AX.25L2V2
 189          * if no DAMA master is available.
 190          */
 191         case AX25_PROTO_DAMA_SLAVE:
 192                 if (!ax25->ax25_dev->dama.slave) ax25_kick(ax25);
 193                 break;
 194 #endif
 195         }
 196 }
 197
 198 /*
 199  *  This procedure is passed a buffer descriptor for an iframe. It builds
 200  *  the rest of the control part of the frame and then writes it out.
 201  */
 202 static void ax25_send_iframe(ax25_cb *ax25, struct sk_buff *skb, int poll_bit)
 203 {
 204         unsigned char *frame;
 205
 206         if (skb == NULL)
 207                 return;
 208
 209         skb->nh.raw = skb->data;
 210
 211         if (ax25->modulus == AX25_MODULUS) {
 212                 frame = skb_push(skb, 1);
 213
 214                 *frame = AX25_I;
 215                 *frame |= (poll_bit) ? AX25_PF : 0;
 216                 *frame |= (ax25->vr << 5);
 217                 *frame |= (ax25->vs << 1);
 218         } else {
 219                 frame = skb_push(skb, 2);
 220
 221                 frame[0] = AX25_I;
 222                 frame[0] |= (ax25->vs << 1);
 223                 frame[1] = (poll_bit) ? AX25_EPF : 0;
 224                 frame[1] |= (ax25->vr << 1);
 225         }
 226
 227         ax25_start_idletimer(ax25);
 228
 229         ax25_transmit_buffer(ax25, skb, AX25_COMMAND);
 230 }
 231
 232 void ax25_kick(ax25_cb *ax25)
 233 {
 234         struct sk_buff *skb, *skbn;
 235         int last = 1;
 236         unsigned short start, end, next;
 237
 238         if (ax25->state != AX25_STATE_3 && ax25->state != AX25_STATE_4)
 239                 return;
 240
 241         if (ax25->condition & AX25_COND_PEER_RX_BUSY)
 242                 return;
 243
 244         if (skb_peek(&ax25->write_queue) == NULL)
 245                 return;
 246
 247         start = (skb_peek(&ax25->ack_queue) == NULL) ? ax25->va : ax25->vs;
 248         end   = (ax25->va + ax25->window) % ax25->modulus;
 249
 250         if (start == end)
 251                 return;
 252
 253         ax25->vs = start;
 254
 255         /*
 256          * Transmit data until either we're out of data to send or
 257          * the window is full. Send a poll on the final I frame if
 258          * the window is filled.
 259          */
 260
 261         /*
 262          * Dequeue the frame and copy it.
 263          */
 264         skb  = skb_dequeue(&ax25->write_queue);
 265
 266         do {
 267                 if ((skbn = skb_clone(skb, GFP_ATOMIC)) == NULL) {
 268                         skb_queue_head(&ax25->write_queue, skb);
 269                         break;
 270                 }
 271
 272                 if (skb->sk != NULL)
 273                         skb_set_owner_w(skbn, skb->sk);
 274
 275                 next = (ax25->vs + 1) % ax25->modulus;
 276                 last = (next == end);
 277
 278                 /*
 279                  * Transmit the frame copy.
 280                  * bke 960114: do not set the Poll bit on the last frame
 281                  * in DAMA mode.
 282                  */
 283                 switch (ax25->ax25_dev->values[AX25_VALUES_PROTOCOL]) {
 284                 case AX25_PROTO_STD_SIMPLEX:
 285                 case AX25_PROTO_STD_DUPLEX:
 286                         ax25_send_iframe(ax25, skbn, (last) ? AX25_POLLON : AX25_POLLOFF);
 287                         break;
 288
 289 #ifdef CONFIG_AX25_DAMA_SLAVE
 290                 case AX25_PROTO_DAMA_SLAVE:
 291                         ax25_send_iframe(ax25, skbn, AX25_POLLOFF);
 292                         break;
 293 #endif
 294                 }
 295
 296                 ax25->vs = next;
 297
 298                 /*
 299                  * Requeue the original data frame.
 300                  */
 301                 skb_queue_tail(&ax25->ack_queue, skb);
 302
 303         } while (!last && (skb = skb_dequeue(&ax25->write_queue)) != NULL);
 304
 305         ax25->condition &= ~AX25_COND_ACK_PENDING;
 306
 307         if (!ax25_t1timer_running(ax25)) {
 308                 ax25_stop_t3timer(ax25);
 309                 ax25_calculate_t1(ax25);
 310                 ax25_start_t1timer(ax25);
 311         }
 312 }
 313
 314 void ax25_transmit_buffer(ax25_cb *ax25, struct sk_buff *skb, int type)
 315 {
 316         struct sk_buff *skbn;
 317         unsigned char *ptr;
 318         int headroom;
 319
 320         if (ax25->ax25_dev == NULL) {
 321                 ax25_disconnect(ax25, ENETUNREACH);
 322                 return;
 323         }
 324
 325         headroom = ax25_addr_size(ax25->digipeat);
 326
 327         if (skb_headroom(skb) < headroom) {
 328                 if ((skbn = skb_realloc_headroom(skb, headroom)) == NULL) {
 329                         printk(KERN_CRIT "AX.25: ax25_transmit_buffer - out of memory\n");
 330                         kfree_skb(skb);
 331                         return;
 332                 }
 333
 334                 if (skb->sk != NULL)
 335                         skb_set_owner_w(skbn, skb->sk);
 336
 337                 kfree_skb(skb);
 338                 skb = skbn;
 339         }
 340
 341         ptr = skb_push(skb, headroom);
 342
 343         ax25_addr_build(ptr, &ax25->source_addr, &ax25->dest_addr, ax25->digipeat, type, ax25->modulus);
 344
 345         ax25_queue_xmit(skb, ax25->ax25_dev->dev);
 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, struct net_device *dev)
 353 {
 354         unsigned char *ptr;
 355
 356         skb->protocol = ax25_type_trans(skb, ax25_fwd_dev(dev));
 357
 358         ptr  = skb_push(skb, 1);
 359         *ptr = 0x00;                    /* KISS */
 360
 361         dev_queue_xmit(skb);
 362 }
 363
 364 int ax25_check_iframes_acked(ax25_cb *ax25, unsigned short nr)
 365 {
 366         if (ax25->vs == nr) {
 367                 ax25_frames_acked(ax25, nr);
 368                 ax25_calculate_rtt(ax25);
 369                 ax25_stop_t1timer(ax25);
 370                 ax25_start_t3timer(ax25);
 371                 return 1;
 372         } else {
 373                 if (ax25->va != nr) {
 374                         ax25_frames_acked(ax25, nr);
 375                         ax25_calculate_t1(ax25);
 376                         ax25_start_t1timer(ax25);
 377                         return 1;
 378                 }
 379         }
 380         return 0;
 381 }
 382