net/ax25/ax25_ip.c

   1 /*
   2  *      AX.25 release 037
   3  *
   4  *      This code REQUIRES 2.1.15 or higher/ NET3.038
   5  *
   6  *      This module:
   7  *              This module is free software; you can redistribute it and/or
   8  *              modify it under the terms of the GNU General Public License
   9  *              as published by the Free Software Foundation; either version
  10  *              2 of the License, or (at your option) any later version.
  11  *
  12  *      History
  13  *      AX.25 036       Jonathan(G4KLX) Split from af_ax25.c.
  14  */
  15
  16 #include <linux/config.h>
  17 #if defined(CONFIG_AX25) || defined(CONFIG_AX25_MODULE)
  18 #include <linux/errno.h>
  19 #include <linux/types.h>
  20 #include <linux/socket.h>
  21 #include <linux/in.h>
  22 #include <linux/kernel.h>
  23 #include <linux/sched.h>
  24 #include <linux/timer.h>
  25 #include <linux/string.h>
  26 #include <linux/sockios.h>
  27 #include <linux/net.h>
  28 #include <net/ax25.h>
  29 #include <linux/inet.h>
  30 #include <linux/netdevice.h>
  31 #include <linux/if_arp.h>
  32 #include <linux/skbuff.h>
  33 #include <net/sock.h>
  34 #include <asm/uaccess.h>
  35 #include <asm/system.h>
  36 #include <linux/fcntl.h>
  37 #include <linux/termios.h>      /* For TIOCINQ/OUTQ */
  38 #include <linux/mm.h>
  39 #include <linux/interrupt.h>
  40 #include <linux/notifier.h>
  41 #include <linux/proc_fs.h>
  42 #include <linux/stat.h>
  43 #include <linux/netfilter.h>
  44 #include <linux/sysctl.h>
  45 #include <net/ip.h>
  46 #include <net/arp.h>
  47
  48 /*
  49  *      IP over AX.25 encapsulation.
  50  */
  51
  52 /*
  53  *      Shove an AX.25 UI header on an IP packet and handle ARP
  54  */
  55
  56 #ifdef CONFIG_INET
  57
  58 int ax25_encapsulate(struct sk_buff *skb, struct net_device *dev, unsigned short type, void *daddr, void *saddr, unsigned len)
  59 {
  60         /* header is an AX.25 UI frame from us to them */
  61         unsigned char *buff = skb_push(skb, AX25_HEADER_LEN);
  62
  63         *buff++ = 0x00; /* KISS DATA */
  64
  65         if (daddr != NULL)
  66                 memcpy(buff, daddr, dev->addr_len);     /* Address specified */
  67
  68         buff[6] &= ~AX25_CBIT;
  69         buff[6] &= ~AX25_EBIT;
  70         buff[6] |= AX25_SSSID_SPARE;
  71         buff    += AX25_ADDR_LEN;
  72
  73         if (saddr != NULL)
  74                 memcpy(buff, saddr, dev->addr_len);
  75         else
  76                 memcpy(buff, dev->dev_addr, dev->addr_len);
  77
  78         buff[6] &= ~AX25_CBIT;
  79         buff[6] |= AX25_EBIT;
  80         buff[6] |= AX25_SSSID_SPARE;
  81         buff    += AX25_ADDR_LEN;
  82
  83         *buff++  = AX25_UI;     /* UI */
  84
  85         /* Append a suitable AX.25 PID */
  86         switch (type) {
  87                 case ETH_P_IP:
  88                         *buff++ = AX25_P_IP;
  89                         break;
  90                 case ETH_P_ARP:
  91                         *buff++ = AX25_P_ARP;
  92                         break;
  93                 default:
  94                         printk(KERN_ERR "AX.25: ax25_encapsulate - wrong protocol type 0x%x2.2\n", type);
  95                         *buff++ = 0;
  96                         break;
  97         }
  98
  99         if (daddr != NULL)
 100                 return AX25_HEADER_LEN;
 101
 102         return -AX25_HEADER_LEN;        /* Unfinished header */
 103 }
 104
 105 int ax25_rebuild_header(struct sk_buff *skb)
 106 {
 107         struct sk_buff *ourskb;
 108         unsigned char *bp  = skb->data;
 109         struct net_device *dev;
 110         ax25_address *src, *dst;
 111         ax25_route *route;
 112         ax25_dev *ax25_dev;
 113
 114         dst = (ax25_address *)(bp + 1);
 115         src = (ax25_address *)(bp + 8);
 116
 117         if (arp_find(bp + 1, skb))
 118                 return 1;
 119
 120         route    = ax25_rt_find_route(dst, NULL);
 121         dev      = route->dev;
 122
 123         if (dev == NULL)
 124                 dev = skb->dev;
 125
 126         if ((ax25_dev = ax25_dev_ax25dev(dev)) == NULL)
 127                 return 1;
 128
 129         if (bp[16] == AX25_P_IP) {
 130                 if (route->ip_mode == 'V' || (route->ip_mode == ' ' && ax25_dev->values[AX25_VALUES_IPDEFMODE])) {
 131                         /*
 132                          *      We copy the buffer and release the original thereby
 133                          *      keeping it straight
 134                          *
 135                          *      Note: we report 1 back so the caller will
 136                          *      not feed the frame direct to the physical device
 137                          *      We don't want that to happen. (It won't be upset
 138                          *      as we have pulled the frame from the queue by
 139                          *      freeing it).
 140                          *
 141                          *      NB: TCP modifies buffers that are still
 142                          *      on a device queue, thus we use skb_copy()
 143                          *      instead of using skb_clone() unless this
 144                          *      gets fixed.
 145                          */
 146
 147                         ax25_address src_c;
 148                         ax25_address dst_c;
 149
 150                         if ((ourskb = skb_copy(skb, GFP_ATOMIC)) == NULL) {
 151                                 kfree_skb(skb);
 152                                 return 1;
 153                         }
 154
 155                         if (skb->sk != NULL)
 156                                 skb_set_owner_w(ourskb, skb->sk);
 157
 158                         kfree_skb(skb);
 159
 160                         src_c = *src;
 161                         dst_c = *dst;
 162
 163                         skb_pull(ourskb, AX25_HEADER_LEN - 1);  /* Keep PID */
 164                         skb->nh.raw = skb->data;
 165
 166                         ax25_send_frame(ourskb, ax25_dev->values[AX25_VALUES_PACLEN], &src_c,
 167 &dst_c, route->digipeat, dev);
 168
 169                         return 1;
 170                 }
 171         }
 172
 173         bp[7]  &= ~AX25_CBIT;
 174         bp[7]  &= ~AX25_EBIT;
 175         bp[7]  |= AX25_SSSID_SPARE;
 176
 177         bp[14] &= ~AX25_CBIT;
 178         bp[14] |= AX25_EBIT;
 179         bp[14] |= AX25_SSSID_SPARE;
 180
 181         skb_pull(skb, AX25_KISS_HEADER_LEN);
 182
 183         if (route->digipeat != NULL) {
 184                 if ((ourskb = ax25_rt_build_path(skb, src, dst, route->digipeat)) == NULL) {
 185                         kfree_skb(skb);
 186                         return 1;
 187                 }
 188
 189                 skb = ourskb;
 190         }
 191
 192         skb->dev      = dev;
 193
 194         ax25_queue_xmit(skb);
 195
 196         return 1;
 197 }
 198
 199 #else   /* INET */
 200
 201 int ax25_encapsulate(struct sk_buff *skb, struct net_device *dev, unsigned short type, void *daddr, void *saddr, unsigned len)
 202 {
 203         return -AX25_HEADER_LEN;
 204 }
 205
 206 int ax25_rebuild_header(struct sk_buff *skb)
 207 {
 208         return 1;
 209 }
 210
 211 #endif
 212
 213 #endif