/*
 * (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'},
	{"sport", 1, 0, '1'},
	{"orig-port-dst", 1, 0, '2'},
	{"dport", 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}
};

#define TCP_NUMBER_OF_OPT	10

static const char *tcp_optflags[TCP_NUMBER_OF_OPT] = {
"sport", "dport", "reply-port-src", "reply-port-dst", "mask-port-src",
"mask-port-dst", "state", "tuple-port-src", "tuple-port-dst"
};

static char tcp_commands_v_options[NUMBER_OF_CMD][TCP_NUMBER_OF_OPT] =
/* Well, it's better than "Re: Sevilla vs Betis" */
{
	    	/* 1 2 3 4 5 6 7 8 9 */
/*CT_LIST*/   	  {2,2,2,2,0,0,2,0,0},
/*CT_CREATE*/	  {1,1,1,1,0,0,1,0,0},
/*CT_UPDATE*/	  {1,1,1,1,0,0,2,0,0},
/*CT_DELETE*/	  {1,1,1,1,0,0,0,0,0},
/*CT_GET*/	  {1,1,1,1,0,0,2,0,0},
/*CT_FLUSH*/	  {0,0,0,0,0,0,0,0,0},
/*CT_EVENT*/	  {2,2,2,2,0,0,2,0,0},
/*CT_VERSION*/	  {0,0,0,0,0,0,0,0,0},
/*CT_HELP*/	  {0,0,0,0,0,0,0,0,0},
/*EXP_LIST*/	  {0,0,0,0,0,0,0,0,0},
/*EXP_CREATE*/	  {1,1,1,1,1,1,0,1,1},
/*EXP_DELETE*/	  {1,1,1,1,0,0,0,0,0},
/*EXP_GET*/	  {1,1,1,1,0,0,0,0,0},
/*EXP_FLUSH*/	  {0,0,0,0,0,0,0,0,0},
/*EXP_EVENT*/	  {0,0,0,0,0,0,0,0,0},
};

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

static void help(void)
{
	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,
			 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)
				exit_error(PARAMETER_PROBLEM,
					   "Unknown TCP state %s\n", optarg);
			*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 void final_check(unsigned int flags,
			unsigned int cmd,
			struct nf_conntrack *ct)
{
	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));
		flags |= TCP_REPL_SPORT;
		flags |= TCP_REPL_DPORT;
	} 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));
		flags |= TCP_ORIG_SPORT;
		flags |= TCP_ORIG_DPORT;
	}

	generic_opt_check(flags, 
			  TCP_NUMBER_OF_OPT,
			  tcp_commands_v_options[cmd],
			  tcp_optflags);
}

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 register_tcp(void)
{
	register_proto(&tcp);
}