/* A reverse-engineered implementation of the EasyCard data format */

/* (C) 2010 by Harald Welte <laforge@gnumonks.org>
 * All Rights Reserved
 *
 * 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 3 of the License, or
 * (at your option) any later version.
 *
 * This program 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 General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License along
 * with this program; if not, write to the Free Software Foundation, Inc.,
 * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
 *
 */

/* System includes */
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <stdint.h>
#include <fcntl.h>
#include <string.h>
#include <time.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <sys/mman.h>
#include <netinet/in.h>

/* libnfc includes */
#include <nfc/nfc-types.h>
#include <nfc/mifaretag.h>

#include "mifare_classic.h"

/* Easycard specific includes */
#include "easycard.h"

#define VERSION	"0.01"
#define COPYRIGHT 						\
	"EasyTool "VERSION"\n"					\
	"(C) 2010 by Harald Welte <laforge@gnumonks.org>\n"	\
	"This is FREE SOFTWARE with ABSOLUTELY NO VARRANTY\n\n"	\
	"Use of this software is only authorized for RESEARCH PURPOSE!\n\n" 

struct {
	int fd;
	unsigned long size;
	mifare_tag *mft;
} global;

/* Sector 0 of Block 2 seems to contain manufacturing timestamp */
struct easy_block2sec0 {
	uint8_t unknown[6];
	uint8_t timestamp[3];
	uint8_t unknown2[7];
} __attribute__ ((packed));

/* Sector 2 of Block 15 */
struct easy_block15sec2 {
	uint8_t unknown[11];
	uint8_t day_of_month;
	uint8_t unknown2;	/* always 0x3d? */
	uint16_t sum_of_day;	/* sum of all shop purchases on a day */
	uint8_t unknown3;
} __attribute__ ((packed));


/* storage of a transaction log record on the transponder itself */
struct easy_log_rec {
	uint8_t trans_id;
	uint8_t unknown;
	uint8_t timestamp[3];	/* seconds since January 1st 1970 / 256 */
	uint8_t trans_type;
	uint16_t amount;	/* transaction amount / value */
	uint16_t remaining;	/* remaining value on card _after_ trans */
	uint8_t unknown2;
	uint8_t station_code;	/* MRT station code */
	uint16_t reader_code;	/* unique code of RFID reader */
	uint8_t unknown3[2];
} __attribute__ ((packed));

/* Mifare classic VALUE BLOCK */
struct mfcl_value_block {
	uint32_t value;		/* value in NTD */
	uint32_t value_inv;	/* bit-inverted copy of value in NTD */
	uint32_t value_backup;	/* backup copy of value in NTD */
	uint8_t addr[4];
} __attribute__ ((packed));

static time_t easy_timestamp2time(const uint8_t *easy_ts)
{
	return (easy_ts[2] << 16 | easy_ts[1] << 8 | easy_ts[0]) << 8;
}

static char tsbuf[64];
char *easy_asc_timestamp(const uint8_t *timestamp)
{
	time_t t_time = easy_timestamp2time(timestamp);
	struct tm *t_tm = gmtime(&t_time);
	memset(tsbuf, 0, sizeof(tsbuf));
	snprintf(tsbuf, sizeof(tsbuf), "%4u-%02u-%02u %02u:%02u",
		t_tm->tm_year+1900, t_tm->tm_mon+1, t_tm->tm_mday,
		t_tm->tm_hour, t_tm->tm_min);
	return tsbuf;
}

static void dump_easy_log(const struct easy_log_rec *elr)
{
	printf("%s | %02x | %10s | Paid %4u NTD | %4u NTD remaining\n",
		easy_asc_timestamp(elr->timestamp),
		elr->trans_id,
		get_value_string(easy_tt_names, elr->trans_type),
		elr->amount, elr->remaining);
	switch (elr->trans_type) {
	case EASY_TT_MRT_ENTER:
	case EASY_TT_MRT_REENTER:
	case EASY_TT_MRT_EXIT:
		printf("\tMRT Station %s\n",
			get_value_string(taipei_mrt_stn_id,
					 elr->station_code));
		break;
	}
}

static void dump_acc_bits(const struct acc_bits_parsed *abp)
{
	uint8_t block;

	for (block = 0; block < 4; block++) {
		printf("\tBlock %u: %x (%u %u %u)\n", block, abp->block[block],
			abp->block[block] & ABP_C1 ? 1 : 0,
			abp->block[block] & ABP_C2 ? 1 : 0,
			abp->block[block] & ABP_C3 ? 1 : 0);
	}
}

static void dump_mfcl(mifare_tag *mft)
{
	unsigned int sect;

	mifare_block_manufacturer *manuf = &mft->amb[0].mbm;

	printf("UID %x, ATQA %x\n", ntohl(*((uint32_t *) manuf->abtUID)),
		ntohs(*((uint16_t *) manuf->abtATQA)));

	for (sect = 0; sect < 16; sect++) {
		unsigned int block_base = sect * 4;
		uint8_t *access_bits = mft->amb[block_base+3].mbt.abtAccessBits;
		struct acc_bits_parsed abp;

		printf("Sector %02u (base: 0x%02x) Access bits: 0x%08x\n", sect,
			sect*4*16, ntohl(*((uint32_t *) access_bits)));
		mfcl_parse_acc_bits(&abp, access_bits);
		dump_acc_bits(&abp);
	}
}

static void dump_easycard(mifare_tag *mft)
{
	unsigned int sect;
	mifare_block_manufacturer *manuf = &mft->amb[0].mbm;
	struct mfcl_value_block *val =
			(struct mfcl_value_block *) mft->amb[8].mbd.abtData;
	struct easy_block2sec0 *b2s0 =
			(struct easy_block2sec0 *) mft->amb[1*4+0].mbd.abtData;
	struct easy_block15sec2 *b15s2 =
			(struct easy_block15sec2 *) mft->amb[15*4+2].mbd.abtData;
	uint32_t uid = *((uint32_t *) manuf->abtUID);

	/* dump the header */
	printf("EasyCard UID 0x%08x (%u)\n", ntohl(uid), uid);
	printf("Date of manufacture: %s\n",
		easy_asc_timestamp(b2s0->timestamp));
	printf("Current Balance: %5u NTD\n", val->value);
	printf("Sum of all purchases on day %u (of month): %u NTD\n",
		b15s2->day_of_month, b15s2->sum_of_day);
	printf("\nTransaction Log:\n");

	/* dump the transaction log */
	for (sect = 3; sect < 6; sect++) {
		unsigned int block_base = sect * 4;
		unsigned int i;
		for (i = 0; i < 3; i++) {
			void *data = mft->amb[block_base+i].mbd.abtData;
			/* first block of sector 3 is not a log record */
			if (sect == 3 && i == 0)
				continue;
			dump_easy_log(data);
		}
	}
}

static void print_help(void)
{
}

int main(int argc, char **argv)
{
	struct stat st;

	printf(COPYRIGHT);

	if (argc < 2) {
		fprintf(stderr, "ERROR: You must specify the file name of "
			"a mifare dump file (.mfd)\n");
		print_help();
		exit(2);
	}

	global.fd = open(argv[1], O_RDONLY);
	if (global.fd < 0) {
		perror("Error opening the MFD file");
		exit(1);
	}
	if (fstat(global.fd, &st) < 0) {
		perror("Error stat()ing the MFD file");
		exit(1);
	}
	global.size = st.st_size;
	global.mft = mmap(NULL, global.size, PROT_READ, MAP_SHARED,
			  global.fd, 0);
	if (!global.mft) {
		perror("Error mmap()ing the MFD file");
		exit(1);
	}

	//dump_mfcl(global.mft);
	dump_easycard(global.mft);

	munmap(global.mft, global.size);
	close(global.fd);
	exit(0);
}