/* Shared library add-on to iptables to add static NAT support.
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Author: Svenning Soerensen <svenning@post5.tele.dk>
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*/
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#include <stdio.h>
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#include <netdb.h>
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#include <string.h>
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#include <stdlib.h>
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#include <getopt.h>
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#include <xtables.h>
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#include <linux/netfilter/nf_nat.h>
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#define MODULENAME "NETMAP"
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enum {
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O_TO = 0,
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};
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static const struct xt_option_entry NETMAP_opts[] = {
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{.name = "to", .id = O_TO, .type = XTTYPE_HOSTMASK,
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.flags = XTOPT_MAND},
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XTOPT_TABLEEND,
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};
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static void NETMAP_help(void)
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{
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printf(MODULENAME" target options:\n"
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" --%s address[/mask]\n"
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" Network address to map to.\n\n",
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NETMAP_opts[0].name);
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}
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static int
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netmask2bits(uint32_t netmask)
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{
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uint32_t bm;
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int bits;
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netmask = ntohl(netmask);
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for (bits = 0, bm = 0x80000000; netmask & bm; netmask <<= 1)
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bits++;
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if (netmask)
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return -1; /* holes in netmask */
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return bits;
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}
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static void NETMAP_init(struct xt_entry_target *t)
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{
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struct nf_nat_ipv4_multi_range_compat *mr = (struct nf_nat_ipv4_multi_range_compat *)t->data;
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/* Actually, it's 0, but it's ignored at the moment. */
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mr->rangesize = 1;
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}
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static void NETMAP_parse(struct xt_option_call *cb)
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{
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struct nf_nat_ipv4_multi_range_compat *mr = cb->data;
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struct nf_nat_ipv4_range *range = &mr->range[0];
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xtables_option_parse(cb);
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range->flags |= NF_NAT_RANGE_MAP_IPS;
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range->min_ip = cb->val.haddr.ip & cb->val.hmask.ip;
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range->max_ip = range->min_ip | ~cb->val.hmask.ip;
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}
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static void __NETMAP_print(const void *ip, const struct xt_entry_target *target,
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int numeric)
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{
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const struct nf_nat_ipv4_multi_range_compat *mr = (const void *)target->data;
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const struct nf_nat_ipv4_range *r = &mr->range[0];
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struct in_addr a;
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int bits;
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a.s_addr = r->min_ip;
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printf("%s", xtables_ipaddr_to_numeric(&a));
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a.s_addr = ~(r->min_ip ^ r->max_ip);
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bits = netmask2bits(a.s_addr);
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if (bits < 0)
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printf("/%s", xtables_ipaddr_to_numeric(&a));
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else
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printf("/%d", bits);
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}
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static void NETMAP_print(const void *ip, const struct xt_entry_target *target,
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int numeric)
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{
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printf(" to:");
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__NETMAP_print(ip, target, numeric);
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}
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static void NETMAP_save(const void *ip, const struct xt_entry_target *target)
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{
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printf(" --%s ", NETMAP_opts[0].name);
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__NETMAP_print(ip, target, 0);
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}
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static struct xtables_target netmap_tg_reg = {
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.name = MODULENAME,
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.version = XTABLES_VERSION,
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.family = NFPROTO_IPV4,
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.size = XT_ALIGN(sizeof(struct nf_nat_ipv4_multi_range_compat)),
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.userspacesize = XT_ALIGN(sizeof(struct nf_nat_ipv4_multi_range_compat)),
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.help = NETMAP_help,
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.init = NETMAP_init,
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.x6_parse = NETMAP_parse,
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.print = NETMAP_print,
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.save = NETMAP_save,
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.x6_options = NETMAP_opts,
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};
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void _init(void)
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{
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xtables_register_target(&netmap_tg_reg);
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}
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