From e49d31c0e798d14d8b0607b953f06dceecb4a42e Mon Sep 17 00:00:00 2001
From: pwpiwi <pwpiwi@users.noreply.github.com>
Date: Wed, 25 Sep 2019 14:24:36 +0200
Subject: [PATCH] fix 'hf iclass sim': * ignore standard iso15693 INVENTORY
 commands silently * make iso15693 command decoder more strict (prevent
 decoding rubbish) * re-enable sim 3

---
 armsrc/iclass.c      |  3 +++
 armsrc/iso15693.c    | 16 ++++++----------
 client/cmdhficlass.c |  7 +++----
 3 files changed, 12 insertions(+), 14 deletions(-)

diff --git a/armsrc/iclass.c b/armsrc/iclass.c
index 23701540..2e3a4db8 100644
--- a/armsrc/iclass.c
+++ b/armsrc/iclass.c
@@ -1128,6 +1128,9 @@ int doIClassSimulation(int simulationMode, uint8_t *reader_mac_buf) {
 				// Otherwise, we should answer 8bytes (block) + 2bytes CRC
 			}
 
+		} else if (receivedCmd[0] == 0x26 && len == 5) {
+			// standard ISO15693 INVENTORY command. Ignore.
+
 		} else {
 			// don't know how to handle this command
 			char debug_message[250]; // should be enough
diff --git a/armsrc/iso15693.c b/armsrc/iso15693.c
index f33e0156..dbc1ca4c 100644
--- a/armsrc/iso15693.c
+++ b/armsrc/iso15693.c
@@ -827,6 +827,7 @@ static int inline __attribute__((always_inline)) Handle15693SampleFromReader(uin
 			break;
 
 		case STATE_READER_RECEIVE_DATA_1_OUT_OF_4:
+			bit = !!bit;
 			DecodeReader->posCount++;
 			if (DecodeReader->posCount == 1) {
 				DecodeReader->sum1 = bit;
@@ -839,17 +840,14 @@ static int inline __attribute__((always_inline)) Handle15693SampleFromReader(uin
 			}
 			if (DecodeReader->posCount == 8) {
 				DecodeReader->posCount = 0;
-				int corr10 = DecodeReader->sum1 - DecodeReader->sum2;
-				int corr01 = DecodeReader->sum2 - DecodeReader->sum1;
-				int corr11 = (DecodeReader->sum1 + DecodeReader->sum2) / 2;
-				if (corr01 > corr11 && corr01 > corr10) { // EOF
+				if (DecodeReader->sum1 <= 1 && DecodeReader->sum2 >= 3) { // EOF
 					LED_B_OFF(); // Finished receiving
 					DecodeReaderReset(DecodeReader);
 					if (DecodeReader->byteCount != 0) {
 						return true;
 					}
 				}
-				if (corr10 > corr11) { // detected a 2bit position
+				if (DecodeReader->sum1 >= 3 && DecodeReader->sum2 <= 1) { // detected a 2bit position
 					DecodeReader->shiftReg >>= 2;
 					DecodeReader->shiftReg |= (DecodeReader->bitCount << 6);
 				}
@@ -869,6 +867,7 @@ static int inline __attribute__((always_inline)) Handle15693SampleFromReader(uin
 			break;
 
 		case STATE_READER_RECEIVE_DATA_1_OUT_OF_256:
+			bit = !!bit;
 			DecodeReader->posCount++;
 			if (DecodeReader->posCount == 1) {
 				DecodeReader->sum1 = bit;
@@ -881,17 +880,14 @@ static int inline __attribute__((always_inline)) Handle15693SampleFromReader(uin
 			}
 			if (DecodeReader->posCount == 8) {
 				DecodeReader->posCount = 0;
-				int corr10 = DecodeReader->sum1 - DecodeReader->sum2;
-				int corr01 = DecodeReader->sum2 - DecodeReader->sum1;
-				int corr11 = (DecodeReader->sum1 + DecodeReader->sum2) / 2;
-				if (corr01 > corr11 && corr01 > corr10) { // EOF
+				if (DecodeReader->sum1 <= 1 && DecodeReader->sum2 >= 3) { // EOF
 					LED_B_OFF(); // Finished receiving
 					DecodeReaderReset(DecodeReader);
 					if (DecodeReader->byteCount != 0) {
 						return true;
 					}
 				}
-				if (corr10 > corr11) { // detected the bit position
+				if (DecodeReader->sum1 >= 3 && DecodeReader->sum2 <= 1) { // detected the bit position
 					DecodeReader->shiftReg = DecodeReader->bitCount;
 				}
 				if (DecodeReader->bitCount == 255) { // we have a full byte
diff --git a/client/cmdhficlass.c b/client/cmdhficlass.c
index 48b62b17..6f7cc4a4 100644
--- a/client/cmdhficlass.c
+++ b/client/cmdhficlass.c
@@ -144,7 +144,7 @@ int CmdHFiClassSim(const char *Cmd) {
 	uint8_t simType = 0;
 	uint8_t CSN[8] = {0, 0, 0, 0, 0, 0, 0, 0};
 
-	if (strlen(Cmd)<1) {
+	if (strlen(Cmd) < 1) {
 		return usage_hf_iclass_sim();
 	}
 	simType = param_get8ex(Cmd, 0, 0, 10);
@@ -157,7 +157,6 @@ int CmdHFiClassSim(const char *Cmd) {
 		PrintAndLog("--simtype:%02x csn:%s", simType, sprint_hex(CSN, 8));
 	}
 
-	uint8_t numberOfCSNs = 0;
 	if (simType == ICLASS_SIM_MODE_READER_ATTACK) {
 		UsbCommand c = {CMD_SIMULATE_TAG_ICLASS, {simType, NUM_CSNS}};
 		UsbCommand resp = {0};
@@ -196,8 +195,8 @@ int CmdHFiClassSim(const char *Cmd) {
 		saveFile("iclass_mac_attack", "bin", dump,datalen);
 		free(dump);
 
-	} else if (simType == ICLASS_SIM_MODE_CSN || simType == ICLASS_SIM_MODE_CSN_DEFAULT) {
-		UsbCommand c = {CMD_SIMULATE_TAG_ICLASS, {simType, numberOfCSNs}};
+	} else if (simType == ICLASS_SIM_MODE_CSN || simType == ICLASS_SIM_MODE_CSN_DEFAULT || simType == ICLASS_SIM_MODE_FULL) {
+		UsbCommand c = {CMD_SIMULATE_TAG_ICLASS, {simType, 0}};
 		memcpy(c.d.asBytes, CSN, 8);
 		SendCommand(&c);
 
-- 
2.39.5