X-Git-Url: http://cvs.zerfleddert.de/cgi-bin/gitweb.cgi/proxmark3-svn/blobdiff_plain/63852b2f5121013884826145e8d2dd2d7dbcf36d..a39944216dd5d765e16917c1092bacc6061b518f:/armsrc/appmain.c?ds=sidebyside

diff --git a/armsrc/appmain.c b/armsrc/appmain.c
index 10db4a39..549feff0 100644
--- a/armsrc/appmain.c
+++ b/armsrc/appmain.c
@@ -9,24 +9,22 @@
 // The main application code. This is the first thing called after start.c
 // executes.
 //-----------------------------------------------------------------------------
-
 #include "usb_cdc.h"
-#include "cmd.h"
-
+//#include "cmd.h"
 #include "proxmark3.h"
 #include "apps.h"
 #include "util.h"
 #include "printf.h"
 #include "string.h"
-
 #include <stdarg.h>
-
 #include "legicrf.h"
-#include <hitag2.h>
+#include "hitag2.h"
+#include "hitagS.h"
 #include "lfsampling.h"
 #include "BigBuf.h"
 #include "mifareutil.h"
 #include "pcf7931.h"
+
 #ifdef WITH_LCD
  #include "LCD.h"
 #endif
@@ -37,8 +35,6 @@
  #include "protocols.h"
 #endif
 
-#define abs(x) ( ((x)<0) ? -(x) : (x) )
-
 //=============================================================================
 // A buffer where we can queue things up to be sent through the FPGA, for
 // any purpose (fake tag, as reader, whatever). We go MSB first, since that
@@ -57,19 +53,17 @@ void ToSendReset(void)
 	ToSendBit = 8;
 }
 
-void ToSendStuffBit(int b)
-{
+void ToSendStuffBit(int b) {
 	if(ToSendBit >= 8) {
-		ToSendMax++;
+		++ToSendMax;
 		ToSend[ToSendMax] = 0;
 		ToSendBit = 0;
 	}
 
-	if(b) {
+	if(b)
 		ToSend[ToSendMax] |= (1 << (7 - ToSendBit));
-	}
 
-	ToSendBit++;
+	++ToSendBit;
 
 	if(ToSendMax >= sizeof(ToSend)) {
 		ToSendBit = 0;
@@ -77,26 +71,44 @@ void ToSendStuffBit(int b)
 	}
 }
 
+void PrintToSendBuffer(void){
+	DbpString("Printing ToSendBuffer:");
+	Dbhexdump(ToSendMax, ToSend, 0);
+}
+
 //=============================================================================
 // Debug print functions, to go out over USB, to the usual PC-side client.
 //=============================================================================
 
-void DbpString(char *str)
-{
-  byte_t len = strlen(str);
-  cmd_send(CMD_DEBUG_PRINT_STRING,len,0,0,(byte_t*)str,len);
+void DbpStringEx(char *str, uint32_t cmd){
+	byte_t len = strlen(str);
+	cmd_send(CMD_DEBUG_PRINT_STRING,len, cmd,0,(byte_t*)str,len);
+}
+
+void DbpString(char *str) {
+	DbpStringEx(str, 0);
 }
 
 #if 0
-void DbpIntegers(int x1, int x2, int x3)
-{
-  cmd_send(CMD_DEBUG_PRINT_INTEGERS,x1,x2,x3,0,0);
+void DbpIntegers(int x1, int x2, int x3) {
+	cmd_send(CMD_DEBUG_PRINT_INTEGERS,x1,x2,x3,0,0);
 }
 #endif
+void DbprintfEx(uint32_t cmd, const char *fmt, ...) {
+	// should probably limit size here; oh well, let's just use a big buffer
+	char output_string[128] = {0x00};
+	va_list ap;
+
+	va_start(ap, fmt);
+	kvsprintf(fmt, output_string, 10, ap);
+	va_end(ap);
+
+	DbpStringEx(output_string, cmd);
+}
 
 void Dbprintf(const char *fmt, ...) {
-// should probably limit size here; oh well, let's just use a big buffer
-	char output_string[128];
+	// should probably limit size here; oh well, let's just use a big buffer
+	char output_string[128] = {0x00};
 	va_list ap;
 
 	va_start(ap, fmt);
@@ -108,28 +120,27 @@ void Dbprintf(const char *fmt, ...) {
 
 // prints HEX & ASCII
 void Dbhexdump(int len, uint8_t *d, bool bAsci) {
-	int l=0,i;
+	int l=0, i;
 	char ascii[9];
     
 	while (len>0) {
-		if (len>8) l=8;
-		else l=len;
+
+		l = (len>8) ? 8 : len;
 		
 		memcpy(ascii,d,l);
 		ascii[l]=0;
 		
 		// filter safe ascii
-		for (i=0;i<l;i++)
+		for (i=0; i<l; ++i)
 			if (ascii[i]<32 || ascii[i]>126) ascii[i]='.';
         
-		if (bAsci) {
+		if (bAsci)
 			Dbprintf("%-8s %*D",ascii,l,d," ");
-		} else {
+		else
 			Dbprintf("%*D",l,d," ");
-		}
         
-		len-=8;
-		d+=8;		
+		len -= 8;
+		d += 8;		
 	}
 }
 
@@ -163,10 +174,9 @@ static int ReadAdc(int ch)
 
 	AT91C_BASE_ADC->ADC_CR = AT91C_ADC_START;
 
-	while(!(AT91C_BASE_ADC->ADC_SR & ADC_END_OF_CONVERSION(ch)))
-		;
+	while (!(AT91C_BASE_ADC->ADC_SR & ADC_END_OF_CONVERSION(ch))) ;
+	
 	d = AT91C_BASE_ADC->ADC_CDR[ch];
-
 	return d;
 }
 
@@ -175,19 +185,20 @@ int AvgAdc(int ch) // was static - merlok
 	int i;
 	int a = 0;
 
-	for(i = 0; i < 32; i++) {
+	for(i = 0; i < 32; ++i)
 		a += ReadAdc(ch);
-	}
 
 	return (a + 15) >> 5;
 }
 
-void MeasureAntennaTuning(void)
-{
+
+void MeasureAntennaTuning(void) {
+
 	uint8_t LF_Results[256];
-	int i, adcval = 0, peak = 0, peakv = 0, peakf = 0; //ptr = 0 
+	int i, adcval = 0, peak = 0, peakv = 0, peakf = 0;
 	int vLf125 = 0, vLf134 = 0, vHf = 0;	// in mV
 
+	memset(LF_Results, 0, sizeof(LF_Results));
 	LED_B_ON();
 
 /*
@@ -201,25 +212,23 @@ void MeasureAntennaTuning(void)
   
   	FpgaDownloadAndGo(FPGA_BITSTREAM_LF);
 	FpgaWriteConfWord(FPGA_MAJOR_MODE_LF_ADC | FPGA_LF_ADC_READER_FIELD);
-	for (i=255; i>=19; i--) {
-    WDT_HIT();
+		
+	for  (i = 255; i >= 19; i--) {
+		WDT_HIT();
 		FpgaSendCommand(FPGA_CMD_SET_DIVISOR, i);
 		SpinDelay(20);
 		adcval = ((MAX_ADC_LF_VOLTAGE * AvgAdc(ADC_CHAN_LF)) >> 10);
 		if (i==95) 	vLf125 = adcval; // voltage at 125Khz
 		if (i==89) 	vLf134 = adcval; // voltage at 134Khz
 
-		LF_Results[i] = adcval>>8; // scale int to fit in byte for graphing purposes
+		LF_Results[i] = adcval >> 8; // scale int to fit in byte for graphing purposes
 		if(LF_Results[i] > peak) {
 			peakv = adcval;
 			peak = LF_Results[i];
 			peakf = i;
-			//ptr = i;
 		}
 	}
 
-	for (i=18; i >= 0; i--) LF_Results[i] = 0;
-	
 	LED_A_ON();
 	// Let the FPGA drive the high-frequency antenna around 13.56 MHz.
 	FpgaDownloadAndGo(FPGA_BITSTREAM_HF);
@@ -227,39 +236,29 @@ void MeasureAntennaTuning(void)
 	SpinDelay(20);
 	vHf = (MAX_ADC_HF_VOLTAGE * AvgAdc(ADC_CHAN_HF)) >> 10;
 
-	cmd_send(CMD_MEASURED_ANTENNA_TUNING, vLf125 | (vLf134<<16), vHf, peakf | (peakv<<16), LF_Results, 256);
+	cmd_send(CMD_MEASURED_ANTENNA_TUNING, vLf125 | (vLf134 << 16), vHf, peakf | (peakv << 16), LF_Results, 256);
 	FpgaWriteConfWord(FPGA_MAJOR_MODE_OFF);
-	LED_A_OFF();
-	LED_B_OFF();
-  return;
+	LEDsoff();
 }
 
-void MeasureAntennaTuningHf(void)
-{
+void MeasureAntennaTuningHf(void) {
 	int vHf = 0;	// in mV
-
-	DbpString("Measuring HF antenna, press button to exit");
-
 	// Let the FPGA drive the high-frequency antenna around 13.56 MHz.
 	FpgaDownloadAndGo(FPGA_BITSTREAM_HF);
 	FpgaWriteConfWord(FPGA_MAJOR_MODE_HF_READER_RX_XCORR);
 
-	for (;;) {
+	while ( !BUTTON_PRESS() ){
 		SpinDelay(20);
 		vHf = (MAX_ADC_HF_VOLTAGE * AvgAdc(ADC_CHAN_HF)) >> 10;
-
-		Dbprintf("%d mV",vHf);
-		if (BUTTON_PRESS()) break;
+		//Dbprintf("%d mV",vHf);
+		DbprintfEx(CMD_MEASURE_ANTENNA_TUNING_HF, "%d mV",vHf);
 	}
-	DbpString("cancelled");
-
 	FpgaWriteConfWord(FPGA_MAJOR_MODE_OFF);
-
+	DbpString("cancelled");
 }
 
 
-void ReadMem(int addr)
-{
+void ReadMem(int addr) {
 	const uint8_t *data = ((uint8_t *)addr);
 
 	Dbprintf("%x: %02x %02x %02x %02x %02x %02x %02x %02x",
@@ -280,6 +279,7 @@ void SendVersion(void)
 	 * pointer, then use it.
 	 */
 	char *bootrom_version = *(char**)&_bootphase1_version_pointer;
+	
 	if( bootrom_version < &_flash_start || bootrom_version >= &_flash_end ) {
 		strcat(VersionString, "bootrom version information appears invalid\n");
 	} else {
@@ -292,6 +292,7 @@ void SendVersion(void)
 
 	FpgaGatherVersion(FPGA_BITSTREAM_LF, temp, sizeof(temp));
 	strncat(VersionString, temp, sizeof(VersionString) - strlen(VersionString) - 1);
+	
 	FpgaGatherVersion(FPGA_BITSTREAM_HF, temp, sizeof(temp));
 	strncat(VersionString, temp, sizeof(VersionString) - strlen(VersionString) - 1);
 
@@ -333,8 +334,7 @@ void printUSBSpeed(void)
 /**
   * Prints runtime information about the PM3.
 **/
-void SendStatus(void)
-{
+void SendStatus(void) {
 	BigBuf_print_status();
 	Fpga_print_status();
 	printConfig(); //LF Sampling config
@@ -661,7 +661,7 @@ void SamyRun()
 			SpinDelay(500);
 
 			CmdHIDdemodFSK(1, &high[selected], &low[selected], 0);
-			Dbprintf("Recorded %x %x %x", selected, high[selected], low[selected]);
+			Dbprintf("Recorded %x %x %08x", selected, high[selected], low[selected]);
 
 			LEDsoff();
 			LED(selected + 1, 0);
@@ -677,7 +677,7 @@ void SamyRun()
 			LED(LED_ORANGE, 0);
 
 			// record
-			Dbprintf("Cloning %x %x %x", selected, high[selected], low[selected]);
+			Dbprintf("Cloning %x %x %08x", selected, high[selected], low[selected]);
 
 			// wait for button to be released
 			while(BUTTON_PRESS())
@@ -686,8 +686,8 @@ void SamyRun()
 			/* need this delay to prevent catching some weird data */
 			SpinDelay(500);
 
-			CopyHIDtoT55x7(high[selected], low[selected], 0, 0);
-			Dbprintf("Cloned %x %x %x", selected, high[selected], low[selected]);
+			CopyHIDtoT55x7(0, high[selected], low[selected], 0);
+			Dbprintf("Cloned %x %x %08x", selected, high[selected], low[selected]);
 
 			LEDsoff();
 			LED(selected + 1, 0);
@@ -718,7 +718,7 @@ void SamyRun()
 				while(BUTTON_PRESS())
 					WDT_HIT();
 				
-				Dbprintf("%x %x %x", selected, high[selected], low[selected]);
+				Dbprintf("%x %x %08x", selected, high[selected], low[selected]);
 				CmdHIDsimTAG(high[selected], low[selected], 0);		
 				DbpString("Done playing");
 				
@@ -782,16 +782,14 @@ static const char LIGHT_SCHEME[] = {
 };
 static const int LIGHT_LEN = sizeof(LIGHT_SCHEME)/sizeof(LIGHT_SCHEME[0]);
 
-void ListenReaderField(int limit)
-{
-	int lf_av, lf_av_new, lf_baseline= 0, lf_max;
-	int hf_av, hf_av_new,  hf_baseline= 0, hf_max;
-	int mode=1, display_val, display_max, i;
-
+void ListenReaderField(int limit) {
 #define LF_ONLY						1
 #define HF_ONLY						2
 #define REPORT_CHANGE			 	10    // report new values only if they have changed at least by REPORT_CHANGE
 
+	int lf_av, lf_av_new, lf_baseline= 0, lf_max;
+	int hf_av, hf_av_new,  hf_baseline= 0, hf_max;
+	int mode=1, display_val, display_max, i;
 
 	// switch off FPGA - we don't want to measure our own signal
 	FpgaDownloadAndGo(FPGA_BITSTREAM_HF);
@@ -833,7 +831,7 @@ void ListenReaderField(int limit)
 
 		if (limit != HF_ONLY) {
 			if(mode == 1) {
-				if (abs(lf_av - lf_baseline) > REPORT_CHANGE) 
+				if (ABS(lf_av - lf_baseline) > REPORT_CHANGE) 
 					LED_D_ON();
 				else
 					LED_D_OFF();
@@ -841,7 +839,7 @@ void ListenReaderField(int limit)
 
 			lf_av_new = AvgAdc(ADC_CHAN_LF);
 			// see if there's a significant change
-			if(abs(lf_av - lf_av_new) > REPORT_CHANGE) {
+			if(ABS(lf_av - lf_av_new) > REPORT_CHANGE) {
 				Dbprintf("LF 125/134kHz Field Change: %5dmV", (MAX_ADC_LF_VOLTAGE * lf_av_new) >> 10);
 				lf_av = lf_av_new;
 				if (lf_av > lf_max)
@@ -851,7 +849,7 @@ void ListenReaderField(int limit)
 
 		if (limit != LF_ONLY) {
 			if (mode == 1){
-				if (abs(hf_av - hf_baseline) > REPORT_CHANGE) 	
+				if (ABS(hf_av - hf_baseline) > REPORT_CHANGE) 	
 					LED_B_ON();
 				else
 					LED_B_OFF();
@@ -859,7 +857,7 @@ void ListenReaderField(int limit)
 
 			hf_av_new = AvgAdc(ADC_CHAN_HF);
 			// see if there's a significant change
-			if(abs(hf_av - hf_av_new) > REPORT_CHANGE) {
+			if(ABS(hf_av - hf_av_new) > REPORT_CHANGE) {
 				Dbprintf("HF 13.56MHz Field Change: %5dmV", (MAX_ADC_HF_VOLTAGE * hf_av_new) >> 10);
 				hf_av = hf_av_new;
 				if (hf_av > hf_max)
@@ -900,7 +898,7 @@ void UsbPacketReceived(uint8_t *packet, int len)
 {
 	UsbCommand *c = (UsbCommand *)packet;
 
-  //Dbprintf("received %d bytes, with command: 0x%04x and args: %d %d %d",len,c->cmd,c->arg[0],c->arg[1],c->arg[2]);
+	//Dbprintf("received %d bytes, with command: 0x%04x and args: %d %d %d",len,c->cmd,c->arg[0],c->arg[1],c->arg[2]);
   
 	switch(c->cmd) {
 #ifdef WITH_LF
@@ -911,7 +909,7 @@ void UsbPacketReceived(uint8_t *packet, int len)
 			cmd_send(CMD_ACK, SampleLF(c->arg[0]),0,0,0,0);
 			break;
 		case CMD_MOD_THEN_ACQUIRE_RAW_ADC_SAMPLES_125K:
-			ModThenAcquireRawAdcSamples125k(c->arg[0],c->arg[1],c->arg[2],c->d.asBytes);
+			ModThenAcquireRawAdcSamples125k(c->arg[0], c->arg[1], c->arg[2], c->d.asBytes);
 			break;
 		case CMD_LF_SNOOP_RAW_ADC_SAMPLES:
 			cmd_send(CMD_ACK,SnoopLF(),0,0,0,0);
@@ -953,7 +951,7 @@ void UsbPacketReceived(uint8_t *packet, int len)
 			WriteTItag(c->arg[0],c->arg[1],c->arg[2]);
 			break;
 		case CMD_SIMULATE_TAG_125K:
-			LED_A_ON();
+			LED_A_ON();		
 			SimulateTagLowFrequency(c->arg[0], c->arg[1], 1);
 			LED_A_OFF();
 			break;
@@ -1008,6 +1006,18 @@ void UsbPacketReceived(uint8_t *packet, int len)
 		case CMD_READER_HITAG: // Reader for Hitag tags, args = type and function
 			ReaderHitag((hitag_function)c->arg[0],(hitag_data*)c->d.asBytes);
 			break;
+		case CMD_SIMULATE_HITAG_S:// Simulate Hitag s tag, args = memory content
+			SimulateHitagSTag((bool)c->arg[0],(byte_t*)c->d.asBytes);
+			break;
+		case CMD_TEST_HITAGS_TRACES:// Tests every challenge within the given file
+			check_challenges((bool)c->arg[0],(byte_t*)c->d.asBytes);
+			break;
+		case CMD_READ_HITAG_S: //Reader for only Hitag S tags, args = key or challenge
+			ReadHitagS((hitag_function)c->arg[0],(hitag_data*)c->d.asBytes);
+			break;
+		case CMD_WR_HITAG_S: //writer for Hitag tags args=data to write,page and key or challenge
+			WritePageHitagS((hitag_function)c->arg[0],(hitag_data*)c->d.asBytes,c->arg[2]);
+			break;
 #endif
 
 #ifdef WITH_ISO15693
@@ -1044,29 +1054,35 @@ void UsbPacketReceived(uint8_t *packet, int len)
 			break;
 
 		case CMD_WRITER_LEGIC_RF:
-			LegicRfWriter(c->arg[1], c->arg[0]);
+			LegicRfWriter( c->arg[0], c->arg[1], c->arg[2]);
+			break;
+
+		case CMD_RAW_WRITER_LEGIC_RF:
+			LegicRfRawWriter(c->arg[0], c->arg[1], c->arg[2]);
 			break;
 
 		case CMD_READER_LEGIC_RF:
-			LegicRfReader(c->arg[0], c->arg[1]);
+			LegicRfReader(c->arg[0], c->arg[1], c->arg[2]);
+			break;
+			
+		case CMD_LEGIC_INFO:
+			LegicRfInfo();
 			break;
 #endif
 
 #ifdef WITH_ISO14443b
-		case CMD_READ_SRI512_TAG:
-			ReadSTMemoryIso14443b(0x0F);
-			break;
-		case CMD_READ_SRIX4K_TAG:
-			ReadSTMemoryIso14443b(0x7F);
+		case CMD_READ_SRI_TAG:
+			ReadSTMemoryIso14443b(c->arg[0]);
 			break;
 		case CMD_SNOOP_ISO_14443B:
 			SnoopIso14443b();
 			break;
 		case CMD_SIMULATE_TAG_ISO_14443B:
-			SimulateIso14443bTag();
+			SimulateIso14443bTag(c->arg[0]);
 			break;
 		case CMD_ISO_14443B_COMMAND:
-			SendRawCommand14443B(c->arg[0],c->arg[1],c->arg[2],c->d.asBytes);
+			//SendRawCommand14443B(c->arg[0],c->arg[1],c->arg[2],c->d.asBytes);
+			SendRawCommand14443B_Ex(c);
 			break;
 #endif
 
@@ -1080,16 +1096,14 @@ void UsbPacketReceived(uint8_t *packet, int len)
 		case CMD_SIMULATE_TAG_ISO_14443a:
 			SimulateIso14443aTag(c->arg[0], c->arg[1], c->d.asBytes);  // ## Simulate iso14443a tag - pass tag type & UID
 			break;
-			
 		case CMD_EPA_PACE_COLLECT_NONCE:
 			EPA_PACE_Collect_Nonce(c);
 			break;
 		case CMD_EPA_PACE_REPLAY:
 			EPA_PACE_Replay(c);
 			break;
-			
 		case CMD_READER_MIFARE:
-            ReaderMifare(c->arg[0], c->arg[1]);
+            ReaderMifare(c->arg[0], c->arg[1], c->arg[2]);
 			break;
 		case CMD_MIFARE_READBL:
 			MifareReadBlock(c->arg[0], c->arg[1], c->arg[2], c->d.asBytes);
@@ -1263,8 +1277,7 @@ void UsbPacketReceived(uint8_t *packet, int len)
 			LED_D_OFF(); // LED D indicates field ON or OFF
 			break;
 
-		case CMD_DOWNLOAD_RAW_ADC_SAMPLES_125K:
-
+		case CMD_DOWNLOAD_RAW_ADC_SAMPLES_125K: {
 			LED_B_ON();
 			uint8_t *BigBuf = BigBuf_get_addr();
 			size_t len = 0;
@@ -1276,13 +1289,26 @@ void UsbPacketReceived(uint8_t *packet, int len)
 			cmd_send(CMD_ACK,1,0,BigBuf_get_traceLen(),getSamplingConfig(),sizeof(sample_config));
 			LED_B_OFF();
 			break;
-
+		}
 		case CMD_DOWNLOADED_SIM_SAMPLES_125K: {
 			uint8_t *b = BigBuf_get_addr();
-			memcpy(b+c->arg[0], c->d.asBytes, USB_CMD_DATA_SIZE);
+			memcpy( b + c->arg[0], c->d.asBytes, USB_CMD_DATA_SIZE);
 			cmd_send(CMD_ACK,0,0,0,0,0);
 			break;
-		}	
+		}
+		case CMD_DOWNLOAD_EML_BIGBUF: {
+			LED_B_ON();
+			uint8_t *cardmem = BigBuf_get_EM_addr();
+			size_t len = 0;
+			for(size_t i=0; i < c->arg[1]; i += USB_CMD_DATA_SIZE) {
+				len = MIN((c->arg[1] - i), USB_CMD_DATA_SIZE);
+				cmd_send(CMD_DOWNLOADED_EML_BIGBUF, i, len, CARD_MEMORY_SIZE, cardmem + c->arg[0] + i, len);
+			}
+			// Trigger a finish downloading signal with an ACK frame
+			cmd_send(CMD_ACK, 1, 0, CARD_MEMORY_SIZE, 0, 0);
+			LED_B_OFF();
+			break;
+		}
 		case CMD_READ_MEM:
 			ReadMem(c->arg[0]);
 			break;
@@ -1362,10 +1388,7 @@ void  __attribute__((noreturn)) AppMain(void)
 	}
 	common_area.flags.osimage_present = 1;
 
-	LED_D_OFF();
-	LED_C_OFF();
-	LED_B_OFF();
-	LED_A_OFF();
+	LEDsoff();
 
 	// Init USB device
 	usb_enable();
@@ -1375,8 +1398,7 @@ void  __attribute__((noreturn)) AppMain(void)
 	AT91C_BASE_PIOA->PIO_PDR = GPIO_PCK0;
 	AT91C_BASE_PMC->PMC_SCER = AT91C_PMC_PCK0;
 	// PCK0 is PLL clock / 4 = 96Mhz / 4 = 24Mhz
-	AT91C_BASE_PMC->PMC_PCKR[0] = AT91C_PMC_CSS_PLL_CLK |
-		AT91C_PMC_PRES_CLK_4; //  4 for 24Mhz pck0, 2 for 48 MHZ pck0
+	AT91C_BASE_PMC->PMC_PCKR[0] = AT91C_PMC_CSS_PLL_CLK | AT91C_PMC_PRES_CLK_4; //  4 for 24Mhz pck0, 2 for 48 MHZ pck0
 	AT91C_BASE_PIOA->PIO_OER = GPIO_PCK0;
 
 	// Reset SPI
@@ -1398,11 +1420,11 @@ void  __attribute__((noreturn)) AppMain(void)
 	size_t rx_len;
   
 	for(;;) {
-		if (usb_poll()) {
-			rx_len = usb_read(rx,sizeof(UsbCommand));
-			if (rx_len) {
-				UsbPacketReceived(rx,rx_len);
-			}
+		if ( usb_poll_validate_length() ) {
+			rx_len = usb_read(rx, sizeof(UsbCommand));
+			
+			if (rx_len)
+				UsbPacketReceived(rx, rx_len);
 		}
 		WDT_HIT();