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 <linux/slab.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         /*
  97          * There is one ref for the state machine; a caller needs
  98          * one more to put it back, just like with the existing one.
  99          */
 100         ax25_cb_hold(ax25);
 101
 102         ax25_cb_add(ax25);
 103
 104         ax25->state = AX25_STATE_1;
 105
 106         ax25_start_heartbeat(ax25);
 107
 108         ax25_output(ax25, paclen, skb);
 109
 110         return ax25;                    /* We had to create it */
 111 }
 112
 113 EXPORT_SYMBOL(ax25_send_frame);
 114
 115 /*
 116  *      All outgoing AX.25 I frames pass via this routine. Therefore this is
 117  *      where the fragmentation of frames takes place. If fragment is set to
 118  *      zero then we are not allowed to do fragmentation, even if the frame
 119  *      is too large.
 120  */
 121 void ax25_output(ax25_cb *ax25, int paclen, struct sk_buff *skb)
 122 {
 123         struct sk_buff *skbn;
 124         unsigned char *p;
 125         int frontlen, len, fragno, ka9qfrag, first = 1;
 126
 127         if (paclen < 16) {
 128                 WARN_ON_ONCE(1);
 129                 kfree_skb(skb);
 130                 return;
 131         }
 132
 133         if ((skb->len - 1) > paclen) {
 134                 if (*skb->data == AX25_P_TEXT) {
 135                         skb_pull(skb, 1); /* skip PID */
 136                         ka9qfrag = 0;
 137                 } else {
 138                         paclen -= 2;    /* Allow for fragment control info */
 139                         ka9qfrag = 1;
 140                 }
 141
 142                 fragno = skb->len / paclen;
 143                 if (skb->len % paclen == 0) fragno--;
 144
 145                 frontlen = skb_headroom(skb);   /* Address space + CTRL */
 146
 147                 while (skb->len > 0) {
 148                         spin_lock_bh(&ax25_frag_lock);
 149                         if ((skbn = alloc_skb(paclen + 2 + frontlen, GFP_ATOMIC)) == NULL) {
 150                                 spin_unlock_bh(&ax25_frag_lock);
 151                                 printk(KERN_CRIT "AX.25: ax25_output - out of memory\n");
 152                                 return;
 153                         }
 154
 155                         if (skb->sk != NULL)
 156                                 skb_set_owner_w(skbn, skb->sk);
 157
 158                         spin_unlock_bh(&ax25_frag_lock);
 159
 160                         len = (paclen > skb->len) ? skb->len : paclen;
 161
 162                         if (ka9qfrag == 1) {
 163                                 skb_reserve(skbn, frontlen + 2);
 164                                 skb_set_network_header(skbn,
 165                                                       skb_network_offset(skb));
 166                                 skb_copy_from_linear_data(skb, skb_put(skbn, len), len);
 167                                 p = skb_push(skbn, 2);
 168
 169                                 *p++ = AX25_P_SEGMENT;
 170
 171                                 *p = fragno--;
 172                                 if (first) {
 173                                         *p |= AX25_SEG_FIRST;
 174                                         first = 0;
 175                                 }
 176                         } else {
 177                                 skb_reserve(skbn, frontlen + 1);
 178                                 skb_set_network_header(skbn,
 179                                                       skb_network_offset(skb));
 180                                 skb_copy_from_linear_data(skb, skb_put(skbn, len), len);
 181                                 p = skb_push(skbn, 1);
 182                                 *p = AX25_P_TEXT;
 183                         }
 184
 185                         skb_pull(skb, len);
 186                         skb_queue_tail(&ax25->write_queue, skbn); /* Throw it on the queue */
 187                 }
 188
 189                 kfree_skb(skb);
 190         } else {
 191                 skb_queue_tail(&ax25->write_queue, skb);          /* Throw it on the queue */
 192         }
 193
 194         switch (ax25->ax25_dev->values[AX25_VALUES_PROTOCOL]) {
 195         case AX25_PROTO_STD_SIMPLEX:
 196         case AX25_PROTO_STD_DUPLEX:
 197                 ax25_kick(ax25);
 198                 break;
 199
 200 #ifdef CONFIG_AX25_DAMA_SLAVE
 201         /*
 202          * A DAMA slave is _required_ to work as normal AX.25L2V2
 203          * if no DAMA master is available.
 204          */
 205         case AX25_PROTO_DAMA_SLAVE:
 206                 if (!ax25->ax25_dev->dama.slave) ax25_kick(ax25);
 207                 break;
 208 #endif
 209         }
 210 }
 211
 212 /*
 213  *  This procedure is passed a buffer descriptor for an iframe. It builds
 214  *  the rest of the control part of the frame and then writes it out.
 215  */
 216 static void ax25_send_iframe(ax25_cb *ax25, struct sk_buff *skb, int poll_bit)
 217 {
 218         unsigned char *frame;
 219
 220         if (skb == NULL)
 221                 return;
 222
 223         skb_reset_network_header(skb);
 224
 225         if (ax25->modulus == AX25_MODULUS) {
 226                 frame = skb_push(skb, 1);
 227
 228                 *frame = AX25_I;
 229                 *frame |= (poll_bit) ? AX25_PF : 0;
 230                 *frame |= (ax25->vr << 5);
 231                 *frame |= (ax25->vs << 1);
 232         } else {
 233                 frame = skb_push(skb, 2);
 234
 235                 frame[0] = AX25_I;
 236                 frame[0] |= (ax25->vs << 1);
 237                 frame[1] = (poll_bit) ? AX25_EPF : 0;
 238                 frame[1] |= (ax25->vr << 1);
 239         }
 240
 241         ax25_start_idletimer(ax25);
 242
 243         ax25_transmit_buffer(ax25, skb, AX25_COMMAND);
 244 }
 245
 246 void ax25_kick(ax25_cb *ax25)
 247 {
 248         struct sk_buff *skb, *skbn;
 249         int last = 1;
 250         unsigned short start, end, next;
 251
 252         if (ax25->state != AX25_STATE_3 && ax25->state != AX25_STATE_4)
 253                 return;
 254
 255         if (ax25->condition & AX25_COND_PEER_RX_BUSY)
 256                 return;
 257
 258         if (skb_peek(&ax25->write_queue) == NULL)
 259                 return;
 260
 261         start = (skb_peek(&ax25->ack_queue) == NULL) ? ax25->va : ax25->vs;
 262         end   = (ax25->va + ax25->window) % ax25->modulus;
 263
 264         if (start == end)
 265                 return;
 266
 267         /*
 268          * Transmit data until either we're out of data to send or
 269          * the window is full. Send a poll on the final I frame if
 270          * the window is filled.
 271          */
 272
 273         /*
 274          * Dequeue the frame and copy it.
 275          * Check for race with ax25_clear_queues().
 276          */
 277         skb  = skb_dequeue(&ax25->write_queue);
 278         if (!skb)
 279                 return;
 280
 281         ax25->vs = start;
 282
 283         do {
 284                 if ((skbn = skb_clone(skb, GFP_ATOMIC)) == NULL) {
 285                         skb_queue_head(&ax25->write_queue, skb);
 286                         break;
 287                 }
 288
 289                 if (skb->sk != NULL)
 290                         skb_set_owner_w(skbn, skb->sk);
 291
 292                 next = (ax25->vs + 1) % ax25->modulus;
 293                 last = (next == end);
 294
 295                 /*
 296                  * Transmit the frame copy.
 297                  * bke 960114: do not set the Poll bit on the last frame
 298                  * in DAMA mode.
 299                  */
 300                 switch (ax25->ax25_dev->values[AX25_VALUES_PROTOCOL]) {
 301                 case AX25_PROTO_STD_SIMPLEX:
 302                 case AX25_PROTO_STD_DUPLEX:
 303                         ax25_send_iframe(ax25, skbn, (last) ? AX25_POLLON : AX25_POLLOFF);
 304                         break;
 305
 306 #ifdef CONFIG_AX25_DAMA_SLAVE
 307                 case AX25_PROTO_DAMA_SLAVE:
 308                         ax25_send_iframe(ax25, skbn, AX25_POLLOFF);
 309                         break;
 310 #endif
 311                 }
 312
 313                 ax25->vs = next;
 314
 315                 /*
 316                  * Requeue the original data frame.
 317                  */
 318                 skb_queue_tail(&ax25->ack_queue, skb);
 319
 320         } while (!last && (skb = skb_dequeue(&ax25->write_queue)) != NULL);
 321
 322         ax25->condition &= ~AX25_COND_ACK_PENDING;
 323
 324         if (!ax25_t1timer_running(ax25)) {
 325                 ax25_stop_t3timer(ax25);
 326                 ax25_calculate_t1(ax25);
 327                 ax25_start_t1timer(ax25);
 328         }
 329 }
 330
 331 void ax25_transmit_buffer(ax25_cb *ax25, struct sk_buff *skb, int type)
 332 {
 333         struct sk_buff *skbn;
 334         unsigned char *ptr;
 335         int headroom;
 336
 337         if (ax25->ax25_dev == NULL) {
 338                 ax25_disconnect(ax25, ENETUNREACH);
 339                 return;
 340         }
 341
 342         headroom = ax25_addr_size(ax25->digipeat);
 343
 344         if (skb_headroom(skb) < headroom) {
 345                 if ((skbn = skb_realloc_headroom(skb, headroom)) == NULL) {
 346                         printk(KERN_CRIT "AX.25: ax25_transmit_buffer - out of memory\n");
 347                         kfree_skb(skb);
 348                         return;
 349                 }
 350
 351                 if (skb->sk != NULL)
 352                         skb_set_owner_w(skbn, skb->sk);
 353
 354                 kfree_skb(skb);
 355                 skb = skbn;
 356         }
 357
 358         ptr = skb_push(skb, headroom);
 359
 360         ax25_addr_build(ptr, &ax25->source_addr, &ax25->dest_addr, ax25->digipeat, type, ax25->modulus);
 361
 362         ax25_queue_xmit(skb, ax25->ax25_dev->dev);
 363 }
 364
 365 /*
 366  *      A small shim to dev_queue_xmit to add the KISS control byte, and do
 367  *      any packet forwarding in operation.
 368  */
 369 void ax25_queue_xmit(struct sk_buff *skb, struct net_device *dev)
 370 {
 371         unsigned char *ptr;
 372
 373         skb->protocol = ax25_type_trans(skb, ax25_fwd_dev(dev));
 374
 375         ptr  = skb_push(skb, 1);
 376         *ptr = 0x00;                    /* KISS */
 377
 378         dev_queue_xmit(skb);
 379 }
 380
 381 int ax25_check_iframes_acked(ax25_cb *ax25, unsigned short nr)
 382 {
 383         if (ax25->vs == nr) {
 384                 ax25_frames_acked(ax25, nr);
 385                 ax25_calculate_rtt(ax25);
 386                 ax25_stop_t1timer(ax25);
 387                 ax25_start_t3timer(ax25);
 388                 return 1;
 389         } else {
 390                 if (ax25->va != nr) {
 391                         ax25_frames_acked(ax25, nr);
 392                         ax25_calculate_t1(ax25);
 393                         ax25_start_t1timer(ax25);
 394                         return 1;
 395                 }
 396         }
 397         return 0;
 398 }
 399