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ipaddr match (from "Writing your own Netfilter module" PDF)
This commit is contained in:
Jan Engelhardt
committed by
Jan Engelhardt
Jan Engelhardt
parent
48ebf55444
commit
867a920fd7
254
extensions/libxt_ipaddr.c
Normal file
254
extensions/libxt_ipaddr.c
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@@ -0,0 +1,254 @@
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/*
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* "ipaddr" demo match extension for iptables
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* written by Jan Engelhardt <jengelh [at] medozas de>, 2008 - 2009
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* released in the Public Domain
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*/
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#include <arpa/inet.h>
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#include <getopt.h>
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#include <stdbool.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#include <xtables.h>
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#include <linux/netfilter.h>
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#include "xt_ipaddr.h"
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static const struct option ipaddr_mt_opts[] = {
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{.name = "ipsrc", .has_arg = true, .val = '1'},
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{.name = "ipdst", .has_arg = true, .val = '2'},
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{NULL},
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};
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static void ipaddr_mt_help(void)
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{
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printf(
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"ipaddr match options:\n"
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"[!] --ipsrc addr Match source address of packet\n"
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"[!] --ipdst addr Match destination address of packet\n"
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);
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}
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static void ipaddr_mt_init(struct xt_entry_match *match)
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{
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struct xt_ipaddr_mtinfo *info = (void *)match->data;
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inet_pton(PF_INET, "192.0.2.137", &info->dst.in);
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}
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static int ipaddr_mt4_parse(int c, char **argv, int invert,
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unsigned int *flags, const void *entry, struct xt_entry_match **match)
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{
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struct xt_ipaddr_mtinfo *info = (void *)(*match)->data;
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struct in_addr *addrs, mask;
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unsigned int naddrs;
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switch (c) {
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case '1': /* --ipsrc */
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if (*flags & XT_IPADDR_SRC)
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xtables_error(PARAMETER_PROBLEM, "xt_ipaddr: "
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"Only use \"--ipsrc\" once!");
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*flags |= XT_IPADDR_SRC;
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info->flags |= XT_IPADDR_SRC;
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if (invert)
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info->flags |= XT_IPADDR_SRC_INV;
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xtables_ipparse_any(optarg, &addrs, &mask, &naddrs);
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if (naddrs != 1)
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xtables_error(PARAMETER_PROBLEM,
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"%s does not resolve to exactly "
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"one address", optarg);
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memcpy(&info->src.in, addrs, sizeof(*addrs));
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return true;
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case '2': /* --ipdst */
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if (*flags & XT_IPADDR_DST)
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xtables_error(PARAMETER_PROBLEM, "xt_ipaddr: "
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"Only use \"--ipdst\" once!");
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*flags |= XT_IPADDR_DST;
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info->flags |= XT_IPADDR_DST;
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if (invert)
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info->flags |= XT_IPADDR_DST_INV;
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addrs = xtables_numeric_to_ipaddr(optarg);
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if (addrs == NULL)
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xtables_error(PARAMETER_PROBLEM, "xt_ipaddr: "
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"Parse error at %s\n", optarg);
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memcpy(&info->dst.in, addrs, sizeof(*addrs));
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return true;
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}
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return false;
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}
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static int ipaddr_mt6_parse(int c, char **argv, int invert,
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unsigned int *flags, const void *entry, struct xt_entry_match **match)
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{
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struct xt_ipaddr_mtinfo *info = (void *)(*match)->data;
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struct in6_addr *addrs;
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switch (c) {
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case '1': /* --ipsrc */
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if (*flags & XT_IPADDR_SRC)
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xtables_error(PARAMETER_PROBLEM, "xt_ipaddr: "
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"Only use \"--ipsrc\" once!");
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*flags |= XT_IPADDR_SRC;
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info->flags |= XT_IPADDR_SRC;
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if (invert)
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info->flags |= XT_IPADDR_SRC_INV;
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addrs = xtables_numeric_to_ip6addr(optarg);
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if (addrs == NULL)
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xtables_error(PARAMETER_PROBLEM, "xt_ipaddr: "
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"Parse error at %s", optarg);
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memcpy(&info->src.in6, addrs, sizeof(*addrs));
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return true;
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case '2': /* --ipdst */
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if (*flags & XT_IPADDR_DST)
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xtables_error(PARAMETER_PROBLEM, "xt_ipaddr: "
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"Only use \"--ipdst\" once!");
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*flags |= XT_IPADDR_DST;
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info->flags |= XT_IPADDR_DST;
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if (invert)
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info->flags |= XT_IPADDR_DST_INV;
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addrs = xtables_numeric_to_ip6addr(optarg);
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if (addrs == NULL)
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xtables_error(PARAMETER_PROBLEM, "xt_ipaddr: "
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"Parse error at %s", optarg);
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memcpy(&info->dst.in6, addrs, sizeof(*addrs));
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return true;
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}
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return false;
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}
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static void ipaddr_mt_check(unsigned int flags)
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{
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if (flags == 0)
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xtables_error(PARAMETER_PROBLEM, "xt_ipaddr: You need to "
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"specify at least \"--ipsrc\" or \"--ipdst\".");
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}
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static void ipaddr_mt4_print(const void *entry,
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const struct xt_entry_match *match, int numeric)
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{
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const struct xt_ipaddr_mtinfo *info = (const void *)match->data;
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if (info->flags & XT_IPADDR_SRC) {
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printf("src IP ");
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if (info->flags & XT_IPADDR_SRC_INV)
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printf("! ");
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printf("%s ", numeric ?
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xtables_ipaddr_to_numeric(&info->src.in) :
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xtables_ipaddr_to_anyname(&info->src.in));
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}
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if (info->flags & XT_IPADDR_DST) {
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printf("dst IP ");
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if (info->flags & XT_IPADDR_DST_INV)
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printf("! ");
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printf("%s ", numeric ?
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xtables_ipaddr_to_numeric(&info->dst.in) :
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xtables_ipaddr_to_anyname(&info->dst.in));
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}
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}
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static void ipaddr_mt6_print(const void *entry,
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const struct xt_entry_match *match, int numeric)
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{
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const struct xt_ipaddr_mtinfo *info = (const void *)match->data;
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if (info->flags & XT_IPADDR_SRC) {
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printf("src IP ");
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if (info->flags & XT_IPADDR_SRC_INV)
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printf("! ");
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printf("%s ", numeric ?
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xtables_ip6addr_to_numeric(&info->src.in6) :
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xtables_ip6addr_to_anyname(&info->src.in6));
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}
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if (info->flags & XT_IPADDR_DST) {
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printf("dst IP ");
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if (info->flags & XT_IPADDR_DST_INV)
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printf("! ");
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printf("%s ", numeric ?
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xtables_ip6addr_to_numeric(&info->dst.in6) :
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xtables_ip6addr_to_anyname(&info->dst.in6));
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}
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}
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static void ipaddr_mt4_save(const void *entry,
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const struct xt_entry_match *match)
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{
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const struct xt_ipaddr_mtinfo *info = (const void *)match->data;
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if (info->flags & XT_IPADDR_SRC) {
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if (info->flags & XT_IPADDR_SRC_INV)
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printf("! ");
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printf("--ipsrc %s ",
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xtables_ipaddr_to_numeric(&info->src.in));
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}
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if (info->flags & XT_IPADDR_DST) {
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if (info->flags & XT_IPADDR_DST_INV)
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printf("! ");
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printf("--ipdst %s ",
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xtables_ipaddr_to_numeric(&info->dst.in));
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}
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}
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static void ipaddr_mt6_save(const void *entry,
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const struct xt_entry_match *match)
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{
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const struct xt_ipaddr_mtinfo *info = (const void *)match->data;
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if (info->flags & XT_IPADDR_SRC) {
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if (info->flags & XT_IPADDR_SRC_INV)
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printf("! ");
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printf("--ipsrc %s ",
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xtables_ip6addr_to_numeric(&info->src.in6));
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}
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if (info->flags & XT_IPADDR_DST) {
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if (info->flags & XT_IPADDR_DST_INV)
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printf("! ");
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printf("--ipdst %s ",
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xtables_ip6addr_to_numeric(&info->dst.in6));
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}
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}
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static struct xtables_match ipaddr_mt_reg = {
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.version = XTABLES_VERSION,
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.name = "ipaddr",
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.revision = 0,
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.family = PF_INET,
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.size = XT_ALIGN(sizeof(struct xt_ipaddr_mtinfo)),
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.userspacesize = XT_ALIGN(sizeof(struct xt_ipaddr_mtinfo)),
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.help = ipaddr_mt_help,
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.init = ipaddr_mt_init,
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.parse = ipaddr_mt4_parse,
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.final_check = ipaddr_mt_check,
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.print = ipaddr_mt4_print,
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.save = ipaddr_mt4_save,
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.extra_opts = ipaddr_mt_opts,
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};
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static struct xtables_match ipaddr_mt6_reg = {
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.version = XTABLES_VERSION,
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.name = "ipaddr",
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.revision = 0,
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.family = PF_INET6,
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.size = XT_ALIGN(sizeof(struct xt_ipaddr_mtinfo)),
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.userspacesize = XT_ALIGN(sizeof(struct xt_ipaddr_mtinfo)),
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.help = ipaddr_mt_help,
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.init = ipaddr_mt_init,
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.parse = ipaddr_mt6_parse,
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.final_check = ipaddr_mt_check,
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.print = ipaddr_mt6_print,
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.save = ipaddr_mt6_save,
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.extra_opts = ipaddr_mt_opts,
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};
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static void _init(void)
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{
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xtables_register_match(&ipaddr_mt_reg);
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xtables_register_match(&ipaddr_mt6_reg);
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}
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