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 <net/sock.h>
  28 #include <asm/uaccess.h>
  29 #include <linux/fcntl.h>
  30 #include <linux/mm.h>
  31 #include <linux/interrupt.h>
  32
  33 static DEFINE_SPINLOCK(ax25_frag_lock);
  34
  35 ax25_cb *ax25_send_frame(struct sk_buff *skb, int paclen, ax25_address *src, ax25_address *dest, ax25_digi *digi, struct net_device *dev)
  36 {
  37         ax25_dev *ax25_dev;
  38         ax25_cb *ax25;
  39
  40         /*
  41          * Take the default packet length for the device if zero is
  42          * specified.
  43          */
  44         if (paclen == 0) {
  45                 if ((ax25_dev = ax25_dev_ax25dev(dev)) == NULL)
  46                         return NULL;
  47
  48                 paclen = ax25_dev->values[AX25_VALUES_PACLEN];
  49         }
  50
  51         /*
  52          * Look for an existing connection.
  53          */
  54         if ((ax25 = ax25_find_cb(src, dest, digi, dev)) != NULL) {
  55                 ax25_output(ax25, paclen, skb);
  56                 return ax25;            /* It already existed */
  57         }
  58
  59         if ((ax25_dev = ax25_dev_ax25dev(dev)) == NULL)
  60                 return NULL;
  61
  62         if ((ax25 = ax25_create_cb()) == NULL)
  63                 return NULL;
  64
  65         ax25_fillin_cb(ax25, ax25_dev);
  66
  67         ax25->source_addr = *src;
  68         ax25->dest_addr   = *dest;
  69
  70         if (digi != NULL) {
  71                 ax25->digipeat = kmemdup(digi, sizeof(*digi), GFP_ATOMIC);
  72                 if (ax25->digipeat == NULL) {
  73                         ax25_cb_put(ax25);
  74                         return NULL;
  75                 }
  76         }
  77
  78         switch (ax25->ax25_dev->values[AX25_VALUES_PROTOCOL]) {
  79         case AX25_PROTO_STD_SIMPLEX:
  80         case AX25_PROTO_STD_DUPLEX:
  81                 ax25_std_establish_data_link(ax25);
  82                 break;
  83
  84 #ifdef CONFIG_AX25_DAMA_SLAVE
  85         case AX25_PROTO_DAMA_SLAVE:
  86                 if (ax25_dev->dama.slave)
  87                         ax25_ds_establish_data_link(ax25);
  88                 else
  89                         ax25_std_establish_data_link(ax25);
  90                 break;
  91 #endif
  92         }
  93
  94         /*
  95          * There is one ref for the state machine; a caller needs
  96          * one more to put it back, just like with the existing one.
  97          */
  98         ax25_cb_hold(ax25);
  99
 100         ax25_cb_add(ax25);
 101
 102         ax25->state = AX25_STATE_1;
 103
 104         ax25_start_heartbeat(ax25);
 105
 106         ax25_output(ax25, paclen, skb);
 107
 108         return ax25;                    /* We had to create it */
 109 }
 110
 111 EXPORT_SYMBOL(ax25_send_frame);
 112
 113 /*
 114  *      All outgoing AX.25 I frames pass via this routine. Therefore this is
 115  *      where the fragmentation of frames takes place. If fragment is set to
 116  *      zero then we are not allowed to do fragmentation, even if the frame
 117  *      is too large.
 118  */
 119 void ax25_output(ax25_cb *ax25, int paclen, struct sk_buff *skb)
 120 {
 121         struct sk_buff *skbn;
 122         unsigned char *p;
 123         int frontlen, len, fragno, ka9qfrag, first = 1;
 124
 125         if (paclen < 16) {
 126                 WARN_ON_ONCE(1);
 127                 kfree_skb(skb);
 128                 return;
 129         }
 130
 131         if ((skb->len - 1) > paclen) {
 132                 if (*skb->data == AX25_P_TEXT) {
 133                         skb_pull(skb, 1); /* skip PID */
 134                         ka9qfrag = 0;
 135                 } else {
 136                         paclen -= 2;    /* Allow for fragment control info */
 137                         ka9qfrag = 1;
 138                 }
 139
 140                 fragno = skb->len / paclen;
 141                 if (skb->len % paclen == 0) fragno--;
 142
 143                 frontlen = skb_headroom(skb);   /* Address space + CTRL */
 144
 145                 while (skb->len > 0) {
 146                         spin_lock_bh(&ax25_frag_lock);
 147                         if ((skbn = alloc_skb(paclen + 2 + frontlen, GFP_ATOMIC)) == NULL) {
 148                                 spin_unlock_bh(&ax25_frag_lock);
 149                                 printk(KERN_CRIT "AX.25: ax25_output - out of memory\n");
 150                                 return;
 151                         }
 152
 153                         if (skb->sk != NULL)
 154                                 skb_set_owner_w(skbn, skb->sk);
 155
 156                         spin_unlock_bh(&ax25_frag_lock);
 157
 158                         len = (paclen > skb->len) ? skb->len : paclen;
 159
 160                         if (ka9qfrag == 1) {
 161                                 skb_reserve(skbn, frontlen + 2);
 162                                 skb_set_network_header(skbn,
 163                                                       skb_network_offset(skb));
 164                                 skb_copy_from_linear_data(skb, skb_put(skbn, len), len);
 165                                 p = skb_push(skbn, 2);
 166
 167                                 *p++ = AX25_P_SEGMENT;
 168
 169                                 *p = fragno--;
 170                                 if (first) {
 171                                         *p |= AX25_SEG_FIRST;
 172                                         first = 0;
 173                                 }
 174                         } else {
 175                                 skb_reserve(skbn, frontlen + 1);
 176                                 skb_set_network_header(skbn,
 177                                                       skb_network_offset(skb));
 178                                 skb_copy_from_linear_data(skb, skb_put(skbn, len), len);
 179                                 p = skb_push(skbn, 1);
 180                                 *p = AX25_P_TEXT;
 181                         }
 182
 183                         skb_pull(skb, len);
 184                         skb_queue_tail(&ax25->write_queue, skbn); /* Throw it on the queue */
 185                 }
 186
 187                 kfree_skb(skb);
 188         } else {
 189                 skb_queue_tail(&ax25->write_queue, skb);          /* Throw it on the queue */
 190         }
 191
 192         switch (ax25->ax25_dev->values[AX25_VALUES_PROTOCOL]) {
 193         case AX25_PROTO_STD_SIMPLEX:
 194         case AX25_PROTO_STD_DUPLEX:
 195                 ax25_kick(ax25);
 196                 break;
 197
 198 #ifdef CONFIG_AX25_DAMA_SLAVE
 199         /*
 200          * A DAMA slave is _required_ to work as normal AX.25L2V2
 201          * if no DAMA master is available.
 202          */
 203         case AX25_PROTO_DAMA_SLAVE:
 204                 if (!ax25->ax25_dev->dama.slave) ax25_kick(ax25);
 205                 break;
 206 #endif
 207         }
 208 }
 209
 210 /*
 211  *  This procedure is passed a buffer descriptor for an iframe. It builds
 212  *  the rest of the control part of the frame and then writes it out.
 213  */
 214 static void ax25_send_iframe(ax25_cb *ax25, struct sk_buff *skb, int poll_bit)
 215 {
 216         unsigned char *frame;
 217
 218         if (skb == NULL)
 219                 return;
 220
 221         skb_reset_network_header(skb);
 222
 223         if (ax25->modulus == AX25_MODULUS) {
 224                 frame = skb_push(skb, 1);
 225
 226                 *frame = AX25_I;
 227                 *frame |= (poll_bit) ? AX25_PF : 0;
 228                 *frame |= (ax25->vr << 5);
 229                 *frame |= (ax25->vs << 1);
 230         } else {
 231                 frame = skb_push(skb, 2);
 232
 233                 frame[0] = AX25_I;
 234                 frame[0] |= (ax25->vs << 1);
 235                 frame[1] = (poll_bit) ? AX25_EPF : 0;
 236                 frame[1] |= (ax25->vr << 1);
 237         }
 238
 239         ax25_start_idletimer(ax25);
 240
 241         ax25_transmit_buffer(ax25, skb, AX25_COMMAND);
 242 }
 243
 244 void ax25_kick(ax25_cb *ax25)
 245 {
 246         struct sk_buff *skb, *skbn;
 247         int last = 1;
 248         unsigned short start, end, next;
 249
 250         if (ax25->state != AX25_STATE_3 && ax25->state != AX25_STATE_4)
 251                 return;
 252
 253         if (ax25->condition & AX25_COND_PEER_RX_BUSY)
 254                 return;
 255
 256         if (skb_peek(&ax25->write_queue) == NULL)
 257                 return;
 258
 259         start = (skb_peek(&ax25->ack_queue) == NULL) ? ax25->va : ax25->vs;
 260         end   = (ax25->va + ax25->window) % ax25->modulus;
 261
 262         if (start == end)
 263                 return;
 264
 265         /*
 266          * Transmit data until either we're out of data to send or
 267          * the window is full. Send a poll on the final I frame if
 268          * the window is filled.
 269          */
 270
 271         /*
 272          * Dequeue the frame and copy it.
 273          * Check for race with ax25_clear_queues().
 274          */
 275         skb  = skb_dequeue(&ax25->write_queue);
 276         if (!skb)
 277                 return;
 278
 279         ax25->vs = start;
 280
 281         do {
 282                 if ((skbn = skb_clone(skb, GFP_ATOMIC)) == NULL) {
 283                         skb_queue_head(&ax25->write_queue, skb);
 284                         break;
 285                 }
 286
 287                 if (skb->sk != NULL)
 288                         skb_set_owner_w(skbn, skb->sk);
 289
 290                 next = (ax25->vs + 1) % ax25->modulus;
 291                 last = (next == end);
 292
 293                 /*
 294                  * Transmit the frame copy.
 295                  * bke 960114: do not set the Poll bit on the last frame
 296                  * in DAMA mode.
 297                  */
 298                 switch (ax25->ax25_dev->values[AX25_VALUES_PROTOCOL]) {
 299                 case AX25_PROTO_STD_SIMPLEX:
 300                 case AX25_PROTO_STD_DUPLEX:
 301                         ax25_send_iframe(ax25, skbn, (last) ? AX25_POLLON : AX25_POLLOFF);
 302                         break;
 303
 304 #ifdef CONFIG_AX25_DAMA_SLAVE
 305                 case AX25_PROTO_DAMA_SLAVE:
 306                         ax25_send_iframe(ax25, skbn, AX25_POLLOFF);
 307                         break;
 308 #endif
 309                 }
 310
 311                 ax25->vs = next;
 312
 313                 /*
 314                  * Requeue the original data frame.
 315                  */
 316                 skb_queue_tail(&ax25->ack_queue, skb);
 317
 318         } while (!last && (skb = skb_dequeue(&ax25->write_queue)) != NULL);
 319
 320         ax25->condition &= ~AX25_COND_ACK_PENDING;
 321
 322         if (!ax25_t1timer_running(ax25)) {
 323                 ax25_stop_t3timer(ax25);
 324                 ax25_calculate_t1(ax25);
 325                 ax25_start_t1timer(ax25);
 326         }
 327 }
 328
 329 void ax25_transmit_buffer(ax25_cb *ax25, struct sk_buff *skb, int type)
 330 {
 331         struct sk_buff *skbn;
 332         unsigned char *ptr;
 333         int headroom;
 334
 335         if (ax25->ax25_dev == NULL) {
 336                 ax25_disconnect(ax25, ENETUNREACH);
 337                 return;
 338         }
 339
 340         headroom = ax25_addr_size(ax25->digipeat);
 341
 342         if (skb_headroom(skb) < headroom) {
 343                 if ((skbn = skb_realloc_headroom(skb, headroom)) == NULL) {
 344                         printk(KERN_CRIT "AX.25: ax25_transmit_buffer - out of memory\n");
 345                         kfree_skb(skb);
 346                         return;
 347                 }
 348
 349                 if (skb->sk != NULL)
 350                         skb_set_owner_w(skbn, skb->sk);
 351
 352                 consume_skb(skb);
 353                 skb = skbn;
 354         }
 355
 356         ptr = skb_push(skb, headroom);
 357
 358         ax25_addr_build(ptr, &ax25->source_addr, &ax25->dest_addr, ax25->digipeat, type, ax25->modulus);
 359
 360         ax25_queue_xmit(skb, ax25->ax25_dev->dev);
 361 }
 362
 363 /*
 364  *      A small shim to dev_queue_xmit to add the KISS control byte, and do
 365  *      any packet forwarding in operation.
 366  */
 367 void ax25_queue_xmit(struct sk_buff *skb, struct net_device *dev)
 368 {
 369         unsigned char *ptr;
 370
 371         skb->protocol = ax25_type_trans(skb, ax25_fwd_dev(dev));
 372
 373         ptr  = skb_push(skb, 1);
 374         *ptr = 0x00;                    /* KISS */
 375
 376         dev_queue_xmit(skb);
 377 }
 378
 379 int ax25_check_iframes_acked(ax25_cb *ax25, unsigned short nr)
 380 {
 381         if (ax25->vs == nr) {
 382                 ax25_frames_acked(ax25, nr);
 383                 ax25_calculate_rtt(ax25);
 384                 ax25_stop_t1timer(ax25);
 385                 ax25_start_t3timer(ax25);
 386                 return 1;
 387         } else {
 388                 if (ax25->va != nr) {
 389                         ax25_frames_acked(ax25, nr);
 390                         ax25_calculate_t1(ax25);
 391                         ax25_start_t1timer(ax25);
 392                         return 1;
 393                 }
 394         }
 395         return 0;
 396 }
 397