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/*
* (C) 2005 by Pablo Neira Ayuso <pablo@eurodev.net>
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
*/
#include <stdio.h>
#include <getopt.h>
#include <stdlib.h>
#include <string.h>
#include <netinet/in.h> /* For htons */
#include <libnetfilter_conntrack/libnetfilter_conntrack.h>
#include "conntrack.h"
static struct option opts[] = {
{"orig-port-src", 1, 0, '1'},
{"orig-port-dst", 1, 0, '2'},
{"reply-port-src", 1, 0, '3'},
{"reply-port-dst", 1, 0, '4'},
{"mask-port-src", 1, 0, '5'},
{"mask-port-dst", 1, 0, '6'},
{"state", 1, 0, '7'},
{0, 0, 0, 0}
};
enum tcp_param_flags {
ORIG_SPORT_BIT = 0,
ORIG_SPORT = (1 << ORIG_SPORT_BIT),
ORIG_DPORT_BIT = 1,
ORIG_DPORT = (1 << ORIG_DPORT_BIT),
REPL_SPORT_BIT = 2,
REPL_SPORT = (1 << REPL_SPORT_BIT),
REPL_DPORT_BIT = 3,
REPL_DPORT = (1 << REPL_DPORT_BIT),
MASK_SPORT_BIT = 4,
MASK_SPORT = (1 << MASK_SPORT_BIT),
MASK_DPORT_BIT = 5,
MASK_DPORT = (1 << MASK_DPORT_BIT),
STATE_BIT = 6,
STATE = (1 << STATE_BIT)
};
static const char *states[] = {
"NONE",
"SYN_SENT",
"SYN_RECV",
"ESTABLISHED",
"FIN_WAIT",
"CLOSE_WAIT",
"LAST_ACK",
"TIME_WAIT",
"CLOSE",
"LISTEN"
};
void help()
{
fprintf(stdout, "--orig-port-src original source port\n");
fprintf(stdout, "--orig-port-dst original destination port\n");
fprintf(stdout, "--reply-port-src reply source port\n");
fprintf(stdout, "--reply-port-dst reply destination port\n");
fprintf(stdout, "--mask-port-src mask source port\n");
fprintf(stdout, "--mask-port-dst mask destination port\n");
fprintf(stdout, "--state TCP state, fe. ESTABLISHED\n");
}
int parse_options(char c, char *argv[],
struct nfct_tuple *orig,
struct nfct_tuple *reply,
struct nfct_tuple *mask,
union nfct_protoinfo *proto,
unsigned int *flags)
{
switch(c) {
case '1':
if (optarg) {
orig->l4src.tcp.port = htons(atoi(optarg));
*flags |= ORIG_SPORT;
}
break;
case '2':
if (optarg) {
orig->l4dst.tcp.port = htons(atoi(optarg));
*flags |= ORIG_DPORT;
}
break;
case '3':
if (optarg) {
reply->l4src.tcp.port = htons(atoi(optarg));
*flags |= REPL_SPORT;
}
break;
case '4':
if (optarg) {
reply->l4dst.tcp.port = htons(atoi(optarg));
*flags |= REPL_DPORT;
}
break;
case '5':
if (optarg) {
mask->l4src.tcp.port = htons(atoi(optarg));
*flags |= MASK_SPORT;
}
break;
case '6':
if (optarg) {
mask->l4dst.tcp.port = htons(atoi(optarg));
*flags |= MASK_DPORT;
}
break;
case '7':
if (optarg) {
int i;
for (i=0; i<10; i++) {
if (strcmp(optarg, states[i]) == 0) {
proto->tcp.state = i;
break;
}
}
if (i == 10) {
printf("doh?\n");
return 0;
}
*flags |= STATE;
}
break;
}
return 1;
}
int final_check(unsigned int flags,
unsigned int command,
struct nfct_tuple *orig,
struct nfct_tuple *reply)
{
int ret = 0;
if ((flags & (ORIG_SPORT|ORIG_DPORT))
&& !(flags & (REPL_SPORT|REPL_DPORT))) {
reply->l4src.tcp.port = orig->l4dst.tcp.port;
reply->l4dst.tcp.port = orig->l4src.tcp.port;
ret = 1;
} else if (!(flags & (ORIG_SPORT|ORIG_DPORT))
&& (flags & (REPL_SPORT|REPL_DPORT))) {
orig->l4src.tcp.port = reply->l4dst.tcp.port;
orig->l4dst.tcp.port = reply->l4src.tcp.port;
ret = 1;
}
if ((flags & (ORIG_SPORT|ORIG_DPORT))
&& ((flags & (REPL_SPORT|REPL_DPORT))))
ret = 1;
/* --state is missing and we are trying to create a conntrack */
if (ret && (command & CT_CREATE) && (!(flags & STATE)))
ret = 0;
return ret;
}
static struct ctproto_handler tcp = {
.name = "tcp",
.protonum = IPPROTO_TCP,
.parse_opts = parse_options,
.final_check = final_check,
.help = help,
.opts = opts,
.version = VERSION,
};
void __attribute__ ((constructor)) init(void);
void init(void)
{
register_proto(&tcp);
}
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