add functions to do comprehensive modifications of last purchase or recharge

4 files changed, 202 insertions, 8 deletions

diff --git a/easytool/easycard.c b/easytool/easycard.c
index 3329ba1..980735d 100644
--- a/easytool/easycard.c
+++ b/easytool/easycard.c
@@ -42,12 +42,13 @@
 /* Easycard specific includes */
 #include "easycard.h"
 
+/* convert from 3byte easycard-timestamp to time_t */
 time_t easy_timestamp2time(const uint8_t *easy_ts)
 {
 	return (easy_ts[2] << 16 | easy_ts[1] << 8 | easy_ts[0]) << 8;
 }
 
-/* apply a telta (positive or negative) to a EasyCard log record */
+/* apply a delta (positive or negative) to a EasyCard log record */
 int easy_update_log_rec(struct easy_log_rec *elr, int16_t delta)
 {
 	int32_t sum = elr->amount + delta;
@@ -104,6 +105,7 @@ static const struct mfcl_addr easy_trans_log_addrs[] = {
 	{ .sector = 5,	.block = 2, },
 };
 
+/* Dump a single transaction log record */
 void easy_dump_log_rec(const struct easy_log_rec *elr)
 {
 	/* Skip empty records */
@@ -128,13 +130,19 @@ void easy_dump_log_rec(const struct easy_log_rec *elr)
 	}
 }
 
-void easy_dump_log(mifare_tag *mft)
+void easy_log_rec_hdr(void)
 {
-	unsigned int i;
-
 	/*     "2010-01-01 01:01 | TID|  Amount  |  Balance |  */
 	puts("Timestamp        | TID|  Amount  |  Balance | Type            | MRT Station");
 	puts("---------------------------------------------------------------------------");
+}
+
+/* Dump the entire transaction log of the given mifare card */
+void easy_dump_log(mifare_tag *mft)
+{
+	unsigned int i;
+
+	easy_log_rec_hdr();
 
 	for (i = 0; i < ARRAY_SIZE(easy_trans_log_addrs); i++) {
 		unsigned int sect = easy_trans_log_addrs[i].sector;
@@ -149,3 +157,171 @@ void easy_dump_log(mifare_tag *mft)
 		easy_dump_log_rec(data);
 	}
 }
+
+static struct easy_log_rec *get_last_trans(mifare_tag *mft, uint8_t type)
+{
+	unsigned int i;
+	time_t last_trans_time = 0;
+	struct easy_log_rec *last_trans = NULL;
+
+	for (i = 0; i < ARRAY_SIZE(easy_trans_log_addrs); i++) {
+		unsigned int sect = easy_trans_log_addrs[i].sector;
+		unsigned int block = easy_trans_log_addrs[i].block;
+		unsigned int block_base = sect * 4;
+		struct easy_log_rec *elr = (struct easy_log_rec *)
+					mft->amb[block_base+block].mbd.abtData;
+
+		if (elr->trans_type != type)
+			continue;
+
+		if (easy_timestamp2time(elr->timestamp) > last_trans_time) {
+			last_trans = elr;
+			last_trans_time = easy_timestamp2time(elr->timestamp);
+		}
+	}
+	return last_trans;
+}
+
+#define MAX_NTD_PER_PURCHASE	1000
+#define MAX_NTD_PER_DAY		3000
+#define MAX_AMOUNT_PER_CARD	5000
+
+/* positive value: make it more expensive.  negative: cheaper */
+int easy_alter_last_purchase(mifare_tag *mft, int16_t delta)
+{
+	struct easy_log_rec *elr;
+	struct mfcl_value_block *val_block =
+			(struct mfcl_value_block *) mft->amb[2*4].mbd.abtData;
+	struct mfcl_value_block *val_block2 =
+			(struct mfcl_value_block *) mft->amb[2*4+1].mbd.abtData;
+	struct easy_sect15blk2 *s15b2 =
+			(struct easy_sect15blk2 *) mft->amb[15*4+2].mbd.abtData;
+	time_t t_time;
+	struct tm *t_tm;
+	int rc;
+
+	/* Step 1: find last purchasing transaction */
+	elr = get_last_trans(mft, EASY_TT_PURCHASE);
+	if (!elr)
+		return -ENOENT;
+
+	printf("Found last transaction log record:\n");
+	easy_log_rec_hdr();
+	easy_dump_log_rec(elr);
+
+	/* Step 2: check if delta is within range */
+	if (delta >= 0) {
+		if (elr->amount + delta > MAX_NTD_PER_PURCHASE) {
+			fprintf(stderr, "%u NTD + delta %d would exceed "
+				"maximum purchase value of %u\n",
+				elr->amount, delta, MAX_NTD_PER_PURCHASE);
+			return -ERANGE;
+		}
+		if (elr->remaining < delta) {
+			fprintf(stderr, "Delta of %d is more than what is "
+				"left on the card (%u)\n", delta, elr->remaining);
+			return -ERANGE;
+		}
+	} else {
+		if (elr->amount < delta) {
+			fprintf(stderr, "Cannot make purchase of %u NTD "
+				"cheaper by %d\n", elr->amount, delta);
+			return -ERANGE;
+		}
+		if (elr->remaining + abs(delta) > MAX_AMOUNT_PER_CARD) {
+			fprintf(stderr, "%u + %u are in excess of maximum "
+				"value the card can hold (%u)\n", elr->remaining,
+				abs(delta), MAX_AMOUNT_PER_CARD);
+			return -ERANGE;
+		}
+	}
+
+	/* Step 3: Make sure the VALUE block and the 'remaining after trans'
+	 * agree */
+	if (elr->remaining != val_block->value) {
+		fprintf(stderr, "Amount remaining after last transaction (%u) "
+			"and VALUE block (%u) are inconsistent\n", elr->remaining,
+			val_block->value);
+		return -EIO;
+	}
+
+	/* Step 4: Actually apply the delta to the transaction */
+	rc = easy_update_log_rec(elr, delta);
+	if (rc < 0)
+		return rc;
+	printf("=> Modified log record:\n");
+	easy_dump_log_rec(elr);
+
+	/* Step 5: Actually apply the delta to the value blocks */
+	/* we need to _subtract_  the value... */
+	rc = mfcl_update_value_block(val_block, -delta);
+	if (rc < 0)
+		return rc;
+	rc = mfcl_update_value_block(val_block2, -delta);
+	if (rc < 0)
+		return rc;
+
+	/* Step 6: Update the 'sum of the day', if needed */
+	t_time = easy_timestamp2time(elr->timestamp);
+ 	t_tm = gmtime(&t_time);
+	if (s15b2->day_of_month == t_tm->tm_mday)
+		easy_update_sum_of_day(s15b2, delta);
+
+	return rc;
+}
+
+/* positive value: make it more expensive.  negative: cheaper */
+int easy_alter_last_recharge(mifare_tag *mft, int16_t delta)
+{
+	struct easy_log_rec *elr;
+	struct mfcl_value_block *val_block =
+			(struct mfcl_value_block *) mft->amb[2*4].mbd.abtData;
+	struct mfcl_value_block *val_block2 =
+			(struct mfcl_value_block *) mft->amb[2*4+1].mbd.abtData;
+	int rc;
+
+	/* Step 1: find last recharging transaction */
+	elr = get_last_trans(mft, EASY_TT_RECHARGE);
+	if (!elr) {
+		fprintf(stderr, "Cannot find a recharge transaction\n");
+		return -ENOENT;
+	}
+
+	printf("Found last transaction log record:\n");
+	easy_log_rec_hdr();
+	easy_dump_log_rec(elr);
+
+	/* Step 2: check if delta is within range */
+	if (elr->remaining + delta > MAX_AMOUNT_PER_CARD) {
+		fprintf(stderr, "%u plus the delta of %d would exceed the "
+			"per-card maximum of %u\n", elr->remaining, delta,
+			MAX_AMOUNT_PER_CARD);
+		return -ERANGE;
+	}
+
+	/* Step 3: Make sure the VALUE block and the 'remaining after trans'
+	 * agree */
+	if (elr->remaining != val_block->value) {
+		fprintf(stderr, "Amount remaining after last transaction (%u) "
+			"and VALUE block (%u) are inconsistent\n", elr->remaining,
+			val_block->value);
+		return -EIO;
+	}
+
+	/* Step 4: Actually apply the delta to the transaction */
+	rc = easy_update_log_rec(elr, delta);
+	if (rc < 0)
+		return rc;
+	printf("=> Modified log record:\n");
+	easy_dump_log_rec(elr);
+
+	/* Step 5: Actually apply the delta to the value blocks */
+	rc = mfcl_update_value_block(val_block, delta);
+	if (rc < 0)
+		return rc;
+	rc = mfcl_update_value_block(val_block2, delta);
+	if (rc < 0)
+		return rc;
+
+	return rc;
+}
diff --git a/easytool/easycard.h b/easytool/easycard.h
index 37caf1f..8979524 100644
--- a/easytool/easycard.h
+++ b/easytool/easycard.h
@@ -1,6 +1,8 @@
 #ifndef EASYCARD_H
 #define EASYCARD_H
 
+#include <nfc/nfc-types.h>
+#include <nfc/mifaretag.h>
 #include "utils.h"
 
 #define EASY_TT_MRT_ENTER	0x00
@@ -52,17 +54,31 @@ struct easy_log_rec {
 	uint8_t unknown3[2];
 } __attribute__ ((packed));
 
+/* functions for data format conversion */
+
 time_t easy_timestamp2time(const uint8_t *easy_ts);
 char *easy_asc_timestamp(const uint8_t *timestamp);
 
-/* apply a telta (positive or negative) to a EasyCard log record */
+/* functions to make a change to individual portions of the card */
+
+/* apply a delta (positive or negative) to a EasyCard log record */
 int easy_update_log_rec(struct easy_log_rec *elr, int16_t delta);
 /* apply a delta to the 'sum of day' record in Sector 15 Block 2 */
 int easy_update_sum_of_day(struct easy_sect15blk2 *s15b2, int16_t delta);
 
-void easy_dump_log_rec(const struct easy_log_rec *elr);
+/* functions to make a comprehensive change, leave all card state in
+ * a consistent state */
 
-typedef mifare_tag;
+/* positive value: make it more expensive.  negative: cheaper */
+int easy_alter_last_purchase(mifare_tag *mft, int16_t delta);
+/* positive value: make it more expensive.  negative: cheaper */
+int easy_alter_last_recharge(mifare_tag *mft, int16_t delta);
+
+/* functions to dump the transaction log */
+
+/* dump a single log record */
+void easy_dump_log_rec(const struct easy_log_rec *elr);
+/* dump the entire transaction log */
 void easy_dump_log(mifare_tag *mft);
 
 #endif /* EASYCARD_H */
diff --git a/easytool/easytool.c b/easytool/easytool.c
index 0e07902..67157c8 100644
--- a/easytool/easytool.c
+++ b/easytool/easytool.c
@@ -41,7 +41,7 @@
 /* Easycard specific includes */
 #include "easycard.h"
 
-#define VERSION	"0.02"
+#define VERSION	"0.03"
 #define COPYRIGHT 						\
 	"EasyTool "VERSION" (C) 2010 by Harald Welte <laforge@gnumonks.org>\n"	\
 	"This is FREE SOFTWARE with ABSOLUTELY NO WARRANTY\n\n"	\
diff --git a/easytool/mifare_classic.h b/easytool/mifare_classic.h
index d27a34e..05b3dc6 100644
--- a/easytool/mifare_classic.h
+++ b/easytool/mifare_classic.h
@@ -26,5 +26,7 @@ struct mfcl_addr {
 	uint8_t block;
 };
 
+/* apply a delta (positive or negative) to a Mifare Classic VALUE block */
+int mfcl_update_value_block(struct mfcl_value_block *mvb, int32_t delta);
 
 #endif