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 (paclen < 16) {
 121                 WARN_ON_ONCE(1);
 122                 kfree_skb(skb);
 123                 return;
 124         }
 125
 126         if ((skb->len - 1) > paclen) {
 127                 if (*skb->data == AX25_P_TEXT) {
 128                         skb_pull(skb, 1); /* skip PID */
 129                         ka9qfrag = 0;
 130                 } else {
 131                         paclen -= 2;    /* Allow for fragment control info */
 132                         ka9qfrag = 1;
 133                 }
 134
 135                 fragno = skb->len / paclen;
 136                 if (skb->len % paclen == 0) fragno--;
 137
 138                 frontlen = skb_headroom(skb);   /* Address space + CTRL */
 139
 140                 while (skb->len > 0) {
 141                         spin_lock_bh(&ax25_frag_lock);
 142                         if ((skbn = alloc_skb(paclen + 2 + frontlen, GFP_ATOMIC)) == NULL) {
 143                                 spin_unlock_bh(&ax25_frag_lock);
 144                                 printk(KERN_CRIT "AX.25: ax25_output - out of memory\n");
 145                                 return;
 146                         }
 147
 148                         if (skb->sk != NULL)
 149                                 skb_set_owner_w(skbn, skb->sk);
 150
 151                         spin_unlock_bh(&ax25_frag_lock);
 152
 153                         len = (paclen > skb->len) ? skb->len : paclen;
 154
 155                         if (ka9qfrag == 1) {
 156                                 skb_reserve(skbn, frontlen + 2);
 157                                 skb_set_network_header(skbn,
 158                                                       skb_network_offset(skb));
 159                                 skb_copy_from_linear_data(skb, skb_put(skbn, len), len);
 160                                 p = skb_push(skbn, 2);
 161
 162                                 *p++ = AX25_P_SEGMENT;
 163
 164                                 *p = fragno--;
 165                                 if (first) {
 166                                         *p |= AX25_SEG_FIRST;
 167                                         first = 0;
 168                                 }
 169                         } else {
 170                                 skb_reserve(skbn, frontlen + 1);
 171                                 skb_set_network_header(skbn,
 172                                                       skb_network_offset(skb));
 173                                 skb_copy_from_linear_data(skb, skb_put(skbn, len), len);
 174                                 p = skb_push(skbn, 1);
 175                                 *p = AX25_P_TEXT;
 176                         }
 177
 178                         skb_pull(skb, len);
 179                         skb_queue_tail(&ax25->write_queue, skbn); /* Throw it on the queue */
 180                 }
 181
 182                 kfree_skb(skb);
 183         } else {
 184                 skb_queue_tail(&ax25->write_queue, skb);          /* Throw it on the queue */
 185         }
 186
 187         switch (ax25->ax25_dev->values[AX25_VALUES_PROTOCOL]) {
 188         case AX25_PROTO_STD_SIMPLEX:
 189         case AX25_PROTO_STD_DUPLEX:
 190                 ax25_kick(ax25);
 191                 break;
 192
 193 #ifdef CONFIG_AX25_DAMA_SLAVE
 194         /*
 195          * A DAMA slave is _required_ to work as normal AX.25L2V2
 196          * if no DAMA master is available.
 197          */
 198         case AX25_PROTO_DAMA_SLAVE:
 199                 if (!ax25->ax25_dev->dama.slave) ax25_kick(ax25);
 200                 break;
 201 #endif
 202         }
 203 }
 204
 205 /*
 206  *  This procedure is passed a buffer descriptor for an iframe. It builds
 207  *  the rest of the control part of the frame and then writes it out.
 208  */
 209 static void ax25_send_iframe(ax25_cb *ax25, struct sk_buff *skb, int poll_bit)
 210 {
 211         unsigned char *frame;
 212
 213         if (skb == NULL)
 214                 return;
 215
 216         skb_reset_network_header(skb);
 217
 218         if (ax25->modulus == AX25_MODULUS) {
 219                 frame = skb_push(skb, 1);
 220
 221                 *frame = AX25_I;
 222                 *frame |= (poll_bit) ? AX25_PF : 0;
 223                 *frame |= (ax25->vr << 5);
 224                 *frame |= (ax25->vs << 1);
 225         } else {
 226                 frame = skb_push(skb, 2);
 227
 228                 frame[0] = AX25_I;
 229                 frame[0] |= (ax25->vs << 1);
 230                 frame[1] = (poll_bit) ? AX25_EPF : 0;
 231                 frame[1] |= (ax25->vr << 1);
 232         }
 233
 234         ax25_start_idletimer(ax25);
 235
 236         ax25_transmit_buffer(ax25, skb, AX25_COMMAND);
 237 }
 238
 239 void ax25_kick(ax25_cb *ax25)
 240 {
 241         struct sk_buff *skb, *skbn;
 242         int last = 1;
 243         unsigned short start, end, next;
 244
 245         if (ax25->state != AX25_STATE_3 && ax25->state != AX25_STATE_4)
 246                 return;
 247
 248         if (ax25->condition & AX25_COND_PEER_RX_BUSY)
 249                 return;
 250
 251         if (skb_peek(&ax25->write_queue) == NULL)
 252                 return;
 253
 254         start = (skb_peek(&ax25->ack_queue) == NULL) ? ax25->va : ax25->vs;
 255         end   = (ax25->va + ax25->window) % ax25->modulus;
 256
 257         if (start == end)
 258                 return;
 259
 260         /*
 261          * Transmit data until either we're out of data to send or
 262          * the window is full. Send a poll on the final I frame if
 263          * the window is filled.
 264          */
 265
 266         /*
 267          * Dequeue the frame and copy it.
 268          * Check for race with ax25_clear_queues().
 269          */
 270         skb  = skb_dequeue(&ax25->write_queue);
 271         if (!skb)
 272                 return;
 273
 274         ax25->vs = start;
 275
 276         do {
 277                 if ((skbn = skb_clone(skb, GFP_ATOMIC)) == NULL) {
 278                         skb_queue_head(&ax25->write_queue, skb);
 279                         break;
 280                 }
 281
 282                 if (skb->sk != NULL)
 283                         skb_set_owner_w(skbn, skb->sk);
 284
 285                 next = (ax25->vs + 1) % ax25->modulus;
 286                 last = (next == end);
 287
 288                 /*
 289                  * Transmit the frame copy.
 290                  * bke 960114: do not set the Poll bit on the last frame
 291                  * in DAMA mode.
 292                  */
 293                 switch (ax25->ax25_dev->values[AX25_VALUES_PROTOCOL]) {
 294                 case AX25_PROTO_STD_SIMPLEX:
 295                 case AX25_PROTO_STD_DUPLEX:
 296                         ax25_send_iframe(ax25, skbn, (last) ? AX25_POLLON : AX25_POLLOFF);
 297                         break;
 298
 299 #ifdef CONFIG_AX25_DAMA_SLAVE
 300                 case AX25_PROTO_DAMA_SLAVE:
 301                         ax25_send_iframe(ax25, skbn, AX25_POLLOFF);
 302                         break;
 303 #endif
 304                 }
 305
 306                 ax25->vs = next;
 307
 308                 /*
 309                  * Requeue the original data frame.
 310                  */
 311                 skb_queue_tail(&ax25->ack_queue, skb);
 312
 313         } while (!last && (skb = skb_dequeue(&ax25->write_queue)) != NULL);
 314
 315         ax25->condition &= ~AX25_COND_ACK_PENDING;
 316
 317         if (!ax25_t1timer_running(ax25)) {
 318                 ax25_stop_t3timer(ax25);
 319                 ax25_calculate_t1(ax25);
 320                 ax25_start_t1timer(ax25);
 321         }
 322 }
 323
 324 void ax25_transmit_buffer(ax25_cb *ax25, struct sk_buff *skb, int type)
 325 {
 326         struct sk_buff *skbn;
 327         unsigned char *ptr;
 328         int headroom;
 329
 330         if (ax25->ax25_dev == NULL) {
 331                 ax25_disconnect(ax25, ENETUNREACH);
 332                 return;
 333         }
 334
 335         headroom = ax25_addr_size(ax25->digipeat);
 336
 337         if (skb_headroom(skb) < headroom) {
 338                 if ((skbn = skb_realloc_headroom(skb, headroom)) == NULL) {
 339                         printk(KERN_CRIT "AX.25: ax25_transmit_buffer - out of memory\n");
 340                         kfree_skb(skb);
 341                         return;
 342                 }
 343
 344                 if (skb->sk != NULL)
 345                         skb_set_owner_w(skbn, skb->sk);
 346
 347                 kfree_skb(skb);
 348                 skb = skbn;
 349         }
 350
 351         ptr = skb_push(skb, headroom);
 352
 353         ax25_addr_build(ptr, &ax25->source_addr, &ax25->dest_addr, ax25->digipeat, type, ax25->modulus);
 354
 355         ax25_queue_xmit(skb, ax25->ax25_dev->dev);
 356 }
 357
 358 /*
 359  *      A small shim to dev_queue_xmit to add the KISS control byte, and do
 360  *      any packet forwarding in operation.
 361  */
 362 void ax25_queue_xmit(struct sk_buff *skb, struct net_device *dev)
 363 {
 364         unsigned char *ptr;
 365
 366         skb->protocol = ax25_type_trans(skb, ax25_fwd_dev(dev));
 367
 368         ptr  = skb_push(skb, 1);
 369         *ptr = 0x00;                    /* KISS */
 370
 371         dev_queue_xmit(skb);
 372 }
 373
 374 int ax25_check_iframes_acked(ax25_cb *ax25, unsigned short nr)
 375 {
 376         if (ax25->vs == nr) {
 377                 ax25_frames_acked(ax25, nr);
 378                 ax25_calculate_rtt(ax25);
 379                 ax25_stop_t1timer(ax25);
 380                 ax25_start_t3timer(ax25);
 381                 return 1;
 382         } else {
 383                 if (ax25->va != nr) {
 384                         ax25_frames_acked(ax25, nr);
 385                         ax25_calculate_t1(ax25);
 386                         ax25_start_t1timer(ax25);
 387                         return 1;
 388                 }
 389         }
 390         return 0;
 391 }
 392