userapps/opensource/ebtables/extensions/ebt_arpreply.c

   1 #include <stdio.h>
   2 #include <stdlib.h>
   3 #include <string.h>
   4 #include <netinet/ether.h>
   5 #include <getopt.h>
   6 #include "../include/ebtables_u.h"
   7 #include <linux/netfilter_bridge/ebt_arpreply.h>
   8
   9 static int mac_supplied;
  10
  11 #define REPLY_MAC '1'
  12 #define REPLY_TARGET '2'
  13 static struct option opts[] =
  14 {
  15         { "arpreply-mac" ,    required_argument, 0, REPLY_MAC    },
  16         { "arpreply-target" , required_argument, 0, REPLY_TARGET },
  17         { 0 }
  18 };
  19
  20 static void print_help()
  21 {
  22         printf(
  23         "arpreply target options:\n"
  24         " --arpreply-mac address           : source MAC of generated reply\n"
  25         " --arpreply-target target         : ACCEPT, DROP, RETURN or CONTINUE\n"
  26         "                                    (standard target is DROP)\n");
  27 }
  28
  29 static void init(struct ebt_entry_target *target)
  30 {
  31         struct ebt_arpreply_info *replyinfo =
  32            (struct ebt_arpreply_info *)target->data;
  33
  34         replyinfo->target = EBT_DROP;
  35         memset(replyinfo->mac, 0, ETH_ALEN);
  36         mac_supplied = 0;
  37 }
  38
  39 #define OPT_REPLY_MAC     0x01
  40 #define OPT_REPLY_TARGET  0x02
  41 static int parse(int c, char **argv, int argc,
  42    const struct ebt_u_entry *entry, unsigned int *flags,
  43    struct ebt_entry_target **target)
  44 {
  45         struct ebt_arpreply_info *replyinfo =
  46            (struct ebt_arpreply_info *)(*target)->data;
  47         struct ether_addr *addr;
  48
  49         switch (c) {
  50         case REPLY_MAC:
  51                 check_option(flags, OPT_REPLY_MAC);
  52                 if (!(addr = ether_aton(optarg)))
  53                         print_error("Problem with specified "
  54                                     "--arpreply-mac mac");
  55                 memcpy(replyinfo->mac, addr, ETH_ALEN);
  56                 mac_supplied = 1;
  57                 break;
  58         case REPLY_TARGET:
  59                 check_option(flags, OPT_REPLY_TARGET);
  60                 if (FILL_TARGET(optarg, replyinfo->target))
  61                         print_error("Illegal --arpreply-target target");
  62                 break;
  63
  64         default:
  65                 return 0;
  66         }
  67         return 1;
  68 }
  69
  70 static void final_check(const struct ebt_u_entry *entry,
  71    const struct ebt_entry_target *target, const char *name,
  72    unsigned int hookmask, unsigned int time)
  73 {
  74         struct ebt_arpreply_info *replyinfo =
  75            (struct ebt_arpreply_info *)target->data;
  76
  77         if (entry->ethproto != ETH_P_ARP || entry->invflags & EBT_IPROTO)
  78                 print_error("For ARP replying the protocol must be "
  79                             "specified as ARP");
  80         if (time == 0 && mac_supplied == 0)
  81                 print_error("No arpreply mac supplied");
  82         if (BASE_CHAIN && replyinfo->target == EBT_RETURN)
  83                 print_error("--arpreply-target RETURN not allowed on "
  84                             "base chain");
  85         CLEAR_BASE_CHAIN_BIT;
  86         if (strcmp(name, "nat") || hookmask & ~(1 << NF_BR_PRE_ROUTING))
  87                 print_error("arpreply only allowed in PREROUTING");
  88 }
  89
  90 static void print(const struct ebt_u_entry *entry,
  91    const struct ebt_entry_target *target)
  92 {
  93         struct ebt_arpreply_info *replyinfo =
  94            (struct ebt_arpreply_info *)target->data;
  95
  96         printf("--arpreply-mac ");
  97         print_mac(replyinfo->mac);
  98         if (replyinfo->target == EBT_DROP)
  99                 return;
 100         printf(" --arpreply-target %s", TARGET_NAME(replyinfo->target));
 101 }
 102
 103 static int compare(const struct ebt_entry_target *t1,
 104    const struct ebt_entry_target *t2)
 105 {
 106         struct ebt_arpreply_info *replyinfo1 =
 107            (struct ebt_arpreply_info *)t1->data;
 108         struct ebt_arpreply_info *replyinfo2 =
 109            (struct ebt_arpreply_info *)t2->data;
 110
 111         return memcmp(replyinfo1->mac, replyinfo2->mac, ETH_ALEN) == 0
 112                 && replyinfo1->target == replyinfo2->target;
 113 }
 114
 115 static struct ebt_u_target arpreply_target =
 116 {
 117         .name           = EBT_ARPREPLY_TARGET,
 118         .size           = sizeof(struct ebt_arpreply_info),
 119         .help           = print_help,
 120         .init           = init,
 121         .parse          = parse,
 122         .final_check    = final_check,
 123         .print          = print,
 124         .compare        = compare,
 125         .extra_ops      = opts,
 126 };
 127
 128 static void _init(void) __attribute__ ((constructor));
 129 static void _init(void)
 130 {
 131         register_target(&arpreply_target);
 132 }