linux/net/ax25/ax25_ip.c
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   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) Jonathan Naylor G4KLX (g4klx@g4klx.demon.co.uk)
   8 */
   9#include <linux/errno.h>
  10#include <linux/types.h>
  11#include <linux/socket.h>
  12#include <linux/in.h>
  13#include <linux/kernel.h>
  14#include <linux/module.h>
  15#include <linux/timer.h>
  16#include <linux/string.h>
  17#include <linux/sockios.h>
  18#include <linux/net.h>
  19#include <linux/slab.h>
  20#include <net/ax25.h>
  21#include <linux/inet.h>
  22#include <linux/netdevice.h>
  23#include <linux/if_arp.h>
  24#include <linux/skbuff.h>
  25#include <net/sock.h>
  26#include <asm/uaccess.h>
  27#include <linux/fcntl.h>
  28#include <linux/termios.h>      /* For TIOCINQ/OUTQ */
  29#include <linux/mm.h>
  30#include <linux/interrupt.h>
  31#include <linux/notifier.h>
  32#include <linux/proc_fs.h>
  33#include <linux/stat.h>
  34#include <linux/netfilter.h>
  35#include <linux/sysctl.h>
  36#include <net/ip.h>
  37#include <net/arp.h>
  38
  39/*
  40 *      IP over AX.25 encapsulation.
  41 */
  42
  43/*
  44 *      Shove an AX.25 UI header on an IP packet and handle ARP
  45 */
  46
  47#ifdef CONFIG_INET
  48
  49int ax25_hard_header(struct sk_buff *skb, struct net_device *dev,
  50                     unsigned short type, const void *daddr,
  51                     const void *saddr, unsigned int len)
  52{
  53        unsigned char *buff;
  54
  55        /* they sometimes come back to us... */
  56        if (type == ETH_P_AX25)
  57                return 0;
  58
  59        /* header is an AX.25 UI frame from us to them */
  60        buff = skb_push(skb, AX25_HEADER_LEN);
  61        *buff++ = 0x00; /* KISS DATA */
  62
  63        if (daddr != NULL)
  64                memcpy(buff, daddr, dev->addr_len);     /* Address specified */
  65
  66        buff[6] &= ~AX25_CBIT;
  67        buff[6] &= ~AX25_EBIT;
  68        buff[6] |= AX25_SSSID_SPARE;
  69        buff    += AX25_ADDR_LEN;
  70
  71        if (saddr != NULL)
  72                memcpy(buff, saddr, dev->addr_len);
  73        else
  74                memcpy(buff, dev->dev_addr, dev->addr_len);
  75
  76        buff[6] &= ~AX25_CBIT;
  77        buff[6] |= AX25_EBIT;
  78        buff[6] |= AX25_SSSID_SPARE;
  79        buff    += AX25_ADDR_LEN;
  80
  81        *buff++  = AX25_UI;     /* UI */
  82
  83        /* Append a suitable AX.25 PID */
  84        switch (type) {
  85        case ETH_P_IP:
  86                *buff++ = AX25_P_IP;
  87                break;
  88        case ETH_P_ARP:
  89                *buff++ = AX25_P_ARP;
  90                break;
  91        default:
  92                printk(KERN_ERR "AX.25: ax25_hard_header - wrong protocol type 0x%2.2x\n", type);
  93                *buff++ = 0;
  94                break;
  95        }
  96
  97        if (daddr != NULL)
  98                return AX25_HEADER_LEN;
  99
 100        return -AX25_HEADER_LEN;        /* Unfinished header */
 101}
 102
 103int ax25_rebuild_header(struct sk_buff *skb)
 104{
 105        struct sk_buff *ourskb;
 106        unsigned char *bp  = skb->data;
 107        ax25_route *route;
 108        struct net_device *dev = NULL;
 109        ax25_address *src, *dst;
 110        ax25_digi *digipeat = NULL;
 111        ax25_dev *ax25_dev;
 112        ax25_cb *ax25;
 113        char ip_mode = ' ';
 114
 115        dst = (ax25_address *)(bp + 1);
 116        src = (ax25_address *)(bp + 8);
 117
 118        if (arp_find(bp + 1, skb))
 119                return 1;
 120
 121        route = ax25_get_route(dst, NULL);
 122        if (route) {
 123                digipeat = route->digipeat;
 124                dev = route->dev;
 125                ip_mode = route->ip_mode;
 126        }
 127
 128        if (dev == NULL)
 129                dev = skb->dev;
 130
 131        if ((ax25_dev = ax25_dev_ax25dev(dev)) == NULL) {
 132                goto put;
 133        }
 134
 135        if (bp[16] == AX25_P_IP) {
 136                if (ip_mode == 'V' || (ip_mode == ' ' && ax25_dev->values[AX25_VALUES_IPDEFMODE])) {
 137                        /*
 138                         *      We copy the buffer and release the original thereby
 139                         *      keeping it straight
 140                         *
 141                         *      Note: we report 1 back so the caller will
 142                         *      not feed the frame direct to the physical device
 143                         *      We don't want that to happen. (It won't be upset
 144                         *      as we have pulled the frame from the queue by
 145                         *      freeing it).
 146                         *
 147                         *      NB: TCP modifies buffers that are still
 148                         *      on a device queue, thus we use skb_copy()
 149                         *      instead of using skb_clone() unless this
 150                         *      gets fixed.
 151                         */
 152
 153                        ax25_address src_c;
 154                        ax25_address dst_c;
 155
 156                        if ((ourskb = skb_copy(skb, GFP_ATOMIC)) == NULL) {
 157                                kfree_skb(skb);
 158                                goto put;
 159                        }
 160
 161                        if (skb->sk != NULL)
 162                                skb_set_owner_w(ourskb, skb->sk);
 163
 164                        kfree_skb(skb);
 165                        /* dl9sau: bugfix
 166                         * after kfree_skb(), dst and src which were pointer
 167                         * to bp which is part of skb->data would not be valid
 168                         * anymore hope that after skb_pull(ourskb, ..) our
 169                         * dsc_c and src_c will not become invalid
 170                         */
 171                        bp  = ourskb->data;
 172                        dst_c = *(ax25_address *)(bp + 1);
 173                        src_c = *(ax25_address *)(bp + 8);
 174
 175                        skb_pull(ourskb, AX25_HEADER_LEN - 1);  /* Keep PID */
 176                        skb_reset_network_header(ourskb);
 177
 178                        ax25=ax25_send_frame(
 179                            ourskb,
 180                            ax25_dev->values[AX25_VALUES_PACLEN],
 181                            &src_c,
 182                            &dst_c, digipeat, dev);
 183                        if (ax25) {
 184                                ax25_cb_put(ax25);
 185                        }
 186                        goto put;
 187                }
 188        }
 189
 190        bp[7]  &= ~AX25_CBIT;
 191        bp[7]  &= ~AX25_EBIT;
 192        bp[7]  |= AX25_SSSID_SPARE;
 193
 194        bp[14] &= ~AX25_CBIT;
 195        bp[14] |= AX25_EBIT;
 196        bp[14] |= AX25_SSSID_SPARE;
 197
 198        skb_pull(skb, AX25_KISS_HEADER_LEN);
 199
 200        if (digipeat != NULL) {
 201                if ((ourskb = ax25_rt_build_path(skb, src, dst, route->digipeat)) == NULL) {
 202                        kfree_skb(skb);
 203                        goto put;
 204                }
 205
 206                skb = ourskb;
 207        }
 208
 209        ax25_queue_xmit(skb, dev);
 210
 211put:
 212        if (route)
 213                ax25_put_route(route);
 214
 215        return 1;
 216}
 217
 218#else   /* INET */
 219
 220int ax25_hard_header(struct sk_buff *skb, struct net_device *dev,
 221                     unsigned short type, const void *daddr,
 222                     const void *saddr, unsigned int len)
 223{
 224        return -AX25_HEADER_LEN;
 225}
 226
 227int ax25_rebuild_header(struct sk_buff *skb)
 228{
 229        return 1;
 230}
 231
 232#endif
 233
 234const struct header_ops ax25_header_ops = {
 235        .create = ax25_hard_header,
 236        .rebuild = ax25_rebuild_header,
 237};
 238
 239EXPORT_SYMBOL(ax25_hard_header);
 240EXPORT_SYMBOL(ax25_rebuild_header);
 241EXPORT_SYMBOL(ax25_header_ops);
 242
 243
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