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/* Shared library add-on to iptables to add state tracking support. */
#include <stdio.h>
#include <netdb.h>
#include <string.h>
#include <stdlib.h>
#include <getopt.h>
#include <xtables.h>
#include <linux/netfilter/nf_conntrack_common.h>
#include <linux/netfilter/xt_state.h>
#ifndef XT_STATE_UNTRACKED
#define XT_STATE_UNTRACKED (1 << (IP_CT_NUMBER + 1))
#endif
/* Function which prints out usage message. */
static void
state_help(void)
{
printf(
"state v%s options:\n"
" [!] --state [INVALID|ESTABLISHED|NEW|RELATED|UNTRACKED][,...]\n"
" State(s) to match\n"
"\n", IPTABLES_VERSION);
}
static const struct option state_opts[] = {
{ "state", 1, NULL, '1' },
{ .name = NULL }
};
static int
state_parse_state(const char *state, size_t strlen, struct xt_state_info *sinfo)
{
if (strncasecmp(state, "INVALID", strlen) == 0)
sinfo->statemask |= XT_STATE_INVALID;
else if (strncasecmp(state, "NEW", strlen) == 0)
sinfo->statemask |= XT_STATE_BIT(IP_CT_NEW);
else if (strncasecmp(state, "ESTABLISHED", strlen) == 0)
sinfo->statemask |= XT_STATE_BIT(IP_CT_ESTABLISHED);
else if (strncasecmp(state, "RELATED", strlen) == 0)
sinfo->statemask |= XT_STATE_BIT(IP_CT_RELATED);
else if (strncasecmp(state, "UNTRACKED", strlen) == 0)
sinfo->statemask |= XT_STATE_UNTRACKED;
else
return 0;
return 1;
}
static void
state_parse_states(const char *arg, struct xt_state_info *sinfo)
{
const char *comma;
while ((comma = strchr(arg, ',')) != NULL) {
if (comma == arg || !state_parse_state(arg, comma-arg, sinfo))
exit_error(PARAMETER_PROBLEM, "Bad state `%s'", arg);
arg = comma+1;
}
if (strlen(arg) == 0 || !state_parse_state(arg, strlen(arg), sinfo))
exit_error(PARAMETER_PROBLEM, "Bad state `%s'", arg);
}
/* Function which parses command options; returns true if it
ate an option */
static int
state_parse(int c, char **argv, int invert, unsigned int *flags,
const void *entry,
struct xt_entry_match **match)
{
struct xt_state_info *sinfo = (struct xt_state_info *)(*match)->data;
switch (c) {
case '1':
check_inverse(optarg, &invert, &optind, 0);
state_parse_states(argv[optind-1], sinfo);
if (invert)
sinfo->statemask = ~sinfo->statemask;
*flags = 1;
break;
default:
return 0;
}
return 1;
}
/* Final check; must have specified --state. */
static void state_final_check(unsigned int flags)
{
if (!flags)
exit_error(PARAMETER_PROBLEM, "You must specify `--state'");
}
static void state_print_state(unsigned int statemask)
{
const char *sep = "";
if (statemask & XT_STATE_INVALID) {
printf("%sINVALID", sep);
sep = ",";
}
if (statemask & XT_STATE_BIT(IP_CT_NEW)) {
printf("%sNEW", sep);
sep = ",";
}
if (statemask & XT_STATE_BIT(IP_CT_RELATED)) {
printf("%sRELATED", sep);
sep = ",";
}
if (statemask & XT_STATE_BIT(IP_CT_ESTABLISHED)) {
printf("%sESTABLISHED", sep);
sep = ",";
}
if (statemask & XT_STATE_UNTRACKED) {
printf("%sUNTRACKED", sep);
sep = ",";
}
printf(" ");
}
/* Prints out the matchinfo. */
static void
state_print(const void *ip,
const struct xt_entry_match *match,
int numeric)
{
struct xt_state_info *sinfo = (struct xt_state_info *)match->data;
printf("state ");
state_print_state(sinfo->statemask);
}
/* Saves the matchinfo in parsable form to stdout. */
static void state_save(const void *ip, const struct xt_entry_match *match)
{
struct xt_state_info *sinfo = (struct xt_state_info *)match->data;
printf("--state ");
state_print_state(sinfo->statemask);
}
static struct xtables_match state_match = {
.family = AF_INET,
.name = "state",
.version = IPTABLES_VERSION,
.size = XT_ALIGN(sizeof(struct xt_state_info)),
.userspacesize = XT_ALIGN(sizeof(struct xt_state_info)),
.help = state_help,
.parse = state_parse,
.final_check = state_final_check,
.print = state_print,
.save = state_save,
.extra_opts = state_opts,
};
static struct xtables_match state_match6 = {
.family = AF_INET6,
.name = "state",
.version = IPTABLES_VERSION,
.size = XT_ALIGN(sizeof(struct xt_state_info)),
.userspacesize = XT_ALIGN(sizeof(struct xt_state_info)),
.help = state_help,
.parse = state_parse,
.final_check = state_final_check,
.print = state_print,
.save = state_save,
.extra_opts = state_opts,
};
void _init(void)
{
xtables_register_match(&state_match);
xtables_register_match(&state_match6);
}
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