/*
 *
 * Copyright (c) 2007-2016 The University of Waikato, Hamilton, New Zealand.
 * All rights reserved.
 *
 * This file is part of libtrace.
 *
 * This code has been developed by the University of Waikato WAND
 * research group. For further information please see http://www.wand.net.nz/
 *
 * libtrace is free software; you can redistribute it and/or modify
 * it under the terms of the GNU Lesser General Public License as published by
 * the Free Software Foundation; either version 3 of the License, or
 * (at your option) any later version.
 *
 * libtrace is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 *
 *
 */


/* Tool that compares two traces and outputs any packets that do not match
 * between the two
 *
 * Author: Shane Alcock
 */

#include "libtrace.h"
#include <stdio.h>
#include <assert.h>
#include <getopt.h>
#include <string.h>
#include <stdlib.h>

#include "libpacketdump.h"

uint32_t max_diff = 0;
uint32_t dumped_diff = 0;

/* Compares the two provided packets. If the packets differ in any fashion,
 * both will be dumped to standard output using libpacketdump followed by a
 * line of asterisks.
 *
 * Note that only the contents of the packet are compared; the framing provided
 * by the trace format, e.g. the ERF or PCAP header, is not examined.
 */
static void per_packet(libtrace_packet_t *a, libtrace_packet_t *b)
{
	char *buf_a, *buf_b;
	libtrace_linktype_t lt;
	uint32_t rem_a, rem_b;


	buf_a = trace_get_packet_buffer(a, &lt, &rem_a);
	buf_b = trace_get_packet_buffer(b, &lt, &rem_b);

	if (rem_a > trace_get_wire_length(a))
		rem_a = trace_get_wire_length(a);
	if (rem_b > trace_get_wire_length(b))
		rem_b = trace_get_wire_length(b);
	

	if (!buf_a && !buf_b)
		return;

	if (!buf_a || !buf_b) {
		trace_dump_packet(a);
		trace_dump_packet(b);
		printf("****************\n");
		dumped_diff ++;
		return;
	}
		

	if (rem_a == 0 || rem_b == 0)
		return;

	if (rem_a != rem_b) {
		trace_dump_packet(a);
		trace_dump_packet(b);
		printf("****************\n");
		dumped_diff ++;
		return;
	}

	/* This is not exactly going to be snappy, but it's the easiest way
	 * to look for differences */
	if (memcmp(buf_a, buf_b, rem_a) != 0) {
		trace_dump_packet(a);
		trace_dump_packet(b);
		printf("****************\n");
		dumped_diff ++;
	}

}

static void usage(char *prog) {
	printf("Usage instructions for %s\n\n", prog);
	printf("\t%s [options] traceA traceB\n\n", prog);
	printf("Supported options:\n");
	printf("\t-m <max>   Stop after <max> differences have been reported\n");

	
	return;

}

int main(int argc, char *argv[])
{
	libtrace_t *trace[2];
	libtrace_packet_t *packet[2];
	int opt;
	
	if (argc<2) {
		usage(argv[0]);
		return -1;
	}

	while ((opt = getopt(argc, argv, "m:")) != EOF) {
		switch (opt) {
			case 'm':
				if (atoi(optarg) < 0) {
					fprintf(stderr, "-m option must not be negative - ignoring\n");
				} else {
					max_diff = (uint32_t) atoi(optarg);
				}
				break;
			default:
				usage(argv[0]);
		}
	}

	if (optind + 2 > argc) {
		usage(argv[0]);
		return -1;
	}
	packet[0] = trace_create_packet();
	packet[1] = trace_create_packet();

	trace[0] = trace_create(argv[optind++]);

	if (trace_is_err(trace[0])) {
		trace_perror(trace[0],"Opening trace file");
		return -1;
	}

	if (trace_start(trace[0])) {
		trace_perror(trace[0],"Starting trace");
		trace_destroy(trace[0]);
		return -1;
	}

	trace[1] = trace_create(argv[optind++]);

	if (trace_is_err(trace[1])) {
		trace_perror(trace[1],"Opening trace file");
		return -1;
	}

	if (trace_start(trace[1])) {
		trace_perror(trace[1],"Starting trace");
		trace_destroy(trace[1]);
		return -1;
	}

	while (trace_read_packet(trace[0], packet[0]) > 0 &&
			trace_read_packet(trace[1], packet[1]) > 0) {

		per_packet(packet[0], packet[1]);

		if (max_diff > 0 && dumped_diff >= max_diff)
			break;

	}

	if (trace_is_err(trace[0])) {
		trace_perror(trace[0],"Reading packets");
		trace_destroy(trace[0]);
		return -1;
	}
	
	if (trace_is_err(trace[1])) {
		trace_perror(trace[1],"Reading packets");
		trace_destroy(trace[1]);
		return -1;
	}

	trace_destroy(trace[0]);
	trace_destroy(trace[1]);
		
	trace_destroy_packet(packet[0]);
	trace_destroy_packet(packet[1]);
	
	if (dumped_diff == 0)
		return 0;
	else
		return 1;
}