/*
 * (C) 2005-2007 by Pablo Neira Ayuso <pablo@netfilter.org>
 *
 *      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 <libnetfilter_conntrack/libnetfilter_conntrack_tcp.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'},
	{"tuple-port-src", 1, 0, '8'},
	{"tuple-port-dst", 1, 0, '9'},
	{0, 0, 0, 0}
};

static const char *states[] = {
	"NONE",
	"SYN_SENT",
	"SYN_RECV",
	"ESTABLISHED",
	"FIN_WAIT",
	"CLOSE_WAIT",
	"LAST_ACK",
	"TIME_WAIT",
	"CLOSE",
	"LISTEN"
};

static void help()
{
	fprintf(stdout, "  --orig-port-src\t\toriginal source port\n");
	fprintf(stdout, "  --orig-port-dst\t\toriginal destination port\n");
	fprintf(stdout, "  --reply-port-src\t\treply source port\n");
	fprintf(stdout, "  --reply-port-dst\t\treply destination port\n");
	fprintf(stdout, "  --mask-port-src\t\tmask source port\n");
	fprintf(stdout, "  --mask-port-dst\t\tmask destination port\n");
	fprintf(stdout, "  --tuple-port-src\t\texpectation tuple src port\n");
	fprintf(stdout, "  --tuple-port-src\t\texpectation tuple dst port\n");
	fprintf(stdout, "  --state\t\t\tTCP state, fe. ESTABLISHED\n");
}

static int parse_options(char c, char *argv[],
			 struct nf_conntrack *ct,
			 struct nf_conntrack *exptuple,
			 struct nf_conntrack *mask,
			 unsigned int *flags)
{
	int i;

	switch(c) {
		case '1':
			if (!optarg)
				break;

			nfct_set_attr_u16(ct, 
					  ATTR_ORIG_PORT_SRC, 
					  htons(atoi(optarg)));

			*flags |= TCP_ORIG_SPORT;
			break;
		case '2':
			if (!optarg)
				break;

			nfct_set_attr_u16(ct, 
					  ATTR_ORIG_PORT_DST, 
					  htons(atoi(optarg)));

			*flags |= TCP_ORIG_DPORT;
			break;
		case '3':
			if (!optarg)
				break;

			nfct_set_attr_u16(ct, 
					  ATTR_REPL_PORT_SRC, 
					  htons(atoi(optarg)));

			*flags |= TCP_REPL_SPORT;
			break;
		case '4':
			if (!optarg)
				break;

			nfct_set_attr_u16(ct, 
					  ATTR_REPL_PORT_DST, 
					  htons(atoi(optarg)));

			*flags |= TCP_REPL_DPORT;
			break;
		case '5':
			if (!optarg)
				break;

			nfct_set_attr_u16(mask, 
					  ATTR_ORIG_PORT_SRC, 
					  htons(atoi(optarg)));

			*flags |= TCP_MASK_SPORT;
			break;
		case '6':
			if (!optarg)
				break;

			nfct_set_attr_u16(mask, 
					  ATTR_ORIG_PORT_DST, 
					  htons(atoi(optarg)));

			*flags |= TCP_MASK_DPORT;
			break;
		case '7':
			if (!optarg)
				break;

			for (i=0; i<10; i++) {
				if (strcmp(optarg, states[i]) == 0) {
					nfct_set_attr_u8(ct,
							 ATTR_TCP_STATE,
							 i);
					break;
				}
			}
			if (i == 10) {
				printf("doh?\n");
				return 0;
			}
			*flags |= TCP_STATE;
			break;
		case '8':
			if (!optarg)
				break;

			nfct_set_attr_u16(exptuple, 
					  ATTR_ORIG_PORT_SRC, 
					  htons(atoi(optarg)));

			*flags |= TCP_EXPTUPLE_SPORT;
			break;
		case '9':
			if (!optarg)
				break;

			nfct_set_attr_u16(exptuple, 
					  ATTR_ORIG_PORT_DST, 
					  htons(atoi(optarg)));

			*flags |= TCP_EXPTUPLE_DPORT;
			break;
	}
	return 1;
}

static int final_check(unsigned int flags,
		       unsigned int command,
		       struct nf_conntrack *ct)
{
	int ret = 0;

	if ((flags & (TCP_ORIG_SPORT|TCP_ORIG_DPORT)) 
	    && !(flags & (TCP_REPL_SPORT|TCP_REPL_DPORT))) {
	    	nfct_set_attr_u16(ct,
				  ATTR_REPL_PORT_SRC, 
				  nfct_get_attr_u16(ct, ATTR_ORIG_PORT_DST));
		nfct_set_attr_u16(ct,
				  ATTR_REPL_PORT_DST,
				  nfct_get_attr_u16(ct, ATTR_ORIG_PORT_SRC));
		ret = 1;
	} else if (!(flags & (TCP_ORIG_SPORT|TCP_ORIG_DPORT))
	            && (flags & (TCP_REPL_SPORT|TCP_REPL_DPORT))) {
	    	nfct_set_attr_u16(ct,
				  ATTR_ORIG_PORT_SRC, 
				  nfct_get_attr_u16(ct, ATTR_REPL_PORT_DST));
		nfct_set_attr_u16(ct,
				  ATTR_ORIG_PORT_DST,
				  nfct_get_attr_u16(ct, ATTR_REPL_PORT_SRC));
		ret = 1;
	}
	if ((flags & (TCP_ORIG_SPORT|TCP_ORIG_DPORT)) 
	    && ((flags & (TCP_REPL_SPORT|TCP_REPL_DPORT))))
		ret = 1;

	/* --state is missing and we are trying to create a conntrack */
	if (ret && (command & CT_CREATE) && (!(flags & TCP_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,
};

static void __attribute__ ((constructor)) init(void);

static void init(void)
{
	register_proto(&tcp);
}