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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 <iptables.h>
#include <linux/netfilter_ipv4/ip_conntrack.h>
#include <linux/netfilter_ipv4/ipt_state.h>
/* Function which prints out usage message. */
static void
help(void)
{
printf(
"state v%s options:\n"
" [!] --state [INVALID|ESTABLISHED|NEW|RELATED][,...]\n"
" State(s) to match\n"
"\n", NETFILTER_VERSION);
}
static struct option opts[] = {
{ "state", 1, 0, '1' },
{0}
};
/* Initialize the match. */
static void
init(struct ipt_entry_match *m, unsigned int *nfcache)
{
/* Can't cache this */
*nfcache |= NFC_UNKNOWN;
}
static int
parse_state(const char *state, size_t strlen, struct ipt_state_info *sinfo)
{
if (strncasecmp(state, "INVALID", strlen) == 0)
sinfo->statemask |= IPT_STATE_INVALID;
else if (strncasecmp(state, "NEW", strlen) == 0)
sinfo->statemask |= IPT_STATE_BIT(IP_CT_NEW);
else if (strncasecmp(state, "ESTABLISHED", strlen) == 0)
sinfo->statemask |= IPT_STATE_BIT(IP_CT_ESTABLISHED);
else if (strncasecmp(state, "RELATED", strlen) == 0)
sinfo->statemask |= IPT_STATE_BIT(IP_CT_RELATED);
else
return 0;
return 1;
}
static void
parse_states(const char *arg, struct ipt_state_info *sinfo)
{
const char *comma;
while ((comma = strchr(arg, ',')) != NULL) {
if (comma == arg || !parse_state(arg, comma-arg, sinfo))
exit_error(PARAMETER_PROBLEM, "Bad state `%s'", arg);
arg = comma+1;
}
if (strlen(arg) == 0 || !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
parse(int c, char **argv, int invert, unsigned int *flags,
const struct ipt_entry *entry,
unsigned int *nfcache,
struct ipt_entry_match **match)
{
struct ipt_state_info *sinfo = (struct ipt_state_info *)(*match)->data;
switch (c) {
case '1':
if (check_inverse(optarg, &invert))
optind++;
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 final_check(unsigned int flags)
{
if (!flags)
exit_error(PARAMETER_PROBLEM, "You must specify `--state'");
}
static void print_state(unsigned int statemask)
{
const char *sep = "";
if (statemask & IPT_STATE_INVALID) {
printf("%sINVALID", sep);
sep = ",";
}
if (statemask & IPT_STATE_BIT(IP_CT_NEW)) {
printf("%sNEW", sep);
sep = ",";
}
if (statemask & IPT_STATE_BIT(IP_CT_RELATED)) {
printf("%sRELATED", sep);
sep = ",";
}
if (statemask & IPT_STATE_BIT(IP_CT_ESTABLISHED)) {
printf("%sESTABLISHED", sep);
sep = ",";
}
printf(" ");
}
/* Prints out the matchinfo. */
static void
print(const struct ipt_ip *ip,
const struct ipt_entry_match *match,
int numeric)
{
struct ipt_state_info *sinfo = (struct ipt_state_info *)match->data;
printf("state ");
print_state(sinfo->statemask);
}
/* Saves the matchinfo in parsable form to stdout. */
static void save(const struct ipt_ip *ip, const struct ipt_entry_match *match)
{
struct ipt_state_info *sinfo = (struct ipt_state_info *)match->data;
printf("--state ");
print_state(sinfo->statemask);
}
struct iptables_match state
= { NULL,
"state",
NETFILTER_VERSION,
IPT_ALIGN(sizeof(struct ipt_state_info)),
IPT_ALIGN(sizeof(struct ipt_state_info)),
&help,
&init,
&parse,
&final_check,
&print,
&save,
opts
};
void _init(void)
{
register_match(&state);
}
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