proxmark3/armsrc/mifaresniff.c

//-----------------------------------------------------------------------------
// Merlok - 2012
//
// This code is licensed to you under the terms of the GNU GPL, version 2 or,
// at your option, any later version. See the LICENSE.txt file for the text of
// the license.
//-----------------------------------------------------------------------------
// Routines to support mifare classic sniffer.
//-----------------------------------------------------------------------------

#include "mifaresniff.h"

//static int sniffState = SNF_INIT;
static uint8_t sniffUIDType = 0;
static uint8_t sniffUID[10] = {0,0,0,0,0,0,0,0,0,0};
static uint8_t sniffATQA[2] = {0,0};
static uint8_t sniffSAK = 0;
static uint8_t sniffBuf[17];
static uint32_t timerData = 0;

//-----------------------------------------------------------------------------
// MIFARE sniffer. 
// 
// if no activity for 2sec, it sends the collected data to the client.
//-----------------------------------------------------------------------------
// "hf mf sniff"
void RAMFUNC SniffMifare(uint8_t param) {
	// param:
	// bit 0 - trigger from first card answer
	// bit 1 - trigger from first reader 7-bit request

	// C(red) A(yellow) B(green)
	LEDsoff();
	iso14443a_setup(FPGA_HF_ISO14443A_SNIFFER);
	
	// Allocate memory from BigBuf for some buffers
	// free all previous allocations first
	BigBuf_free(); BigBuf_Clear_ext(false);
	clear_trace();
	set_tracing(true);

	// The command (reader -> tag) that we're receiving.
	uint8_t receivedCmd[MAX_MIFARE_FRAME_SIZE] = {0x00};	
	uint8_t receivedCmdPar[MAX_MIFARE_PARITY_SIZE] = {0x00};

	// The response (tag -> reader) that we're receiving.
	uint8_t receivedResp[MAX_MIFARE_FRAME_SIZE] = {0x00};
	uint8_t receivedRespPar[MAX_MIFARE_PARITY_SIZE] = {0x00};

	// allocate the DMA buffer, used to stream samples from the FPGA
	uint8_t *dmaBuf = BigBuf_malloc(DMA_BUFFER_SIZE);
	uint8_t *data = dmaBuf;
	uint8_t previous_data = 0;
	int maxDataLen = 0;
	int dataLen = 0;
	bool ReaderIsActive = false;
	bool TagIsActive = false;

	// We won't start recording the frames that we acquire until we trigger;
	// a good trigger condition to get started is probably when we see a
	// response from the tag.
	// triggered == false -- to wait first for card
	//bool triggered = !(param & 0x03); 
	
	
	// Set up the demodulator for tag -> reader responses.
	DemodInit(receivedResp, receivedRespPar);

	// Set up the demodulator for the reader -> tag commands
	UartInit(receivedCmd, receivedCmdPar);

	// Setup and start DMA.
	// set transfer address and number of bytes. Start transfer.
	if ( !FpgaSetupSscDma(dmaBuf, DMA_BUFFER_SIZE) ){
		if (MF_DBGLEVEL > 1) Dbprintf("[!] FpgaSetupSscDma failed. Exiting"); 
		return;
	}

	tUart* uart = GetUart();
	tDemod* demod = GetDemod();
	
	MfSniffInit();
	
	uint32_t sniffCounter = 0;
    // loop and listen
	while (!BUTTON_PRESS()) {
		WDT_HIT();
		LED_A_ON();
/*
 		if ((sniffCounter & 0x0000FFFF) == 0) {	// from time to time
			// check if a transaction is completed (timeout after 2000ms).
			// if yes, stop the DMA transfer and send what we have so far to the client
			if (BigBuf_get_traceLen()) {
				MfSniffSend();
				// Reset everything - we missed some sniffed data anyway while the DMA was stopped
				sniffCounter = 0;				
				dmaBuf = BigBuf_malloc(DMA_BUFFER_SIZE);
				data = dmaBuf;
				maxDataLen = 0;
				ReaderIsActive = false;
				TagIsActive = false;
				FpgaSetupSscDma((uint8_t *)dmaBuf, DMA_BUFFER_SIZE); // set transfer address and number of bytes. Start transfer.
			}
		}
		*/
		
		// number of bytes we have processed so far		
		int register readBufDataP = data - dmaBuf;	
		// number of bytes already transferred		
		int register dmaBufDataP = DMA_BUFFER_SIZE - AT91C_BASE_PDC_SSC->PDC_RCR;
		if (readBufDataP <= dmaBufDataP)			// we are processing the same block of data which is currently being transferred
			dataLen = dmaBufDataP - readBufDataP;	// number of bytes still to be processed
		else
			dataLen = DMA_BUFFER_SIZE - readBufDataP + dmaBufDataP; // number of bytes still to be processed

		// test for length of buffer
		if (dataLen > maxDataLen) {					// we are more behind than ever...
			maxDataLen = dataLen;					
			if (dataLen > (9 * DMA_BUFFER_SIZE / 10)) {
				Dbprintf("[!] blew circular buffer! | datalen %u", dataLen);		
				break;
			}
		}
		if (dataLen < 1) continue;

		// primary buffer was stopped ( <-- we lost data!
		if (!AT91C_BASE_PDC_SSC->PDC_RCR) {
			AT91C_BASE_PDC_SSC->PDC_RPR = (uint32_t)dmaBuf;
			AT91C_BASE_PDC_SSC->PDC_RCR = DMA_BUFFER_SIZE;
			Dbprintf("[-] RxEmpty ERROR | data length %d", dataLen); // temporary
		}
		// secondary buffer sets as primary, secondary buffer was stopped
		if (!AT91C_BASE_PDC_SSC->PDC_RNCR) {
			AT91C_BASE_PDC_SSC->PDC_RNPR = (uint32_t)dmaBuf;
			AT91C_BASE_PDC_SSC->PDC_RNCR = DMA_BUFFER_SIZE;
		}

		LED_A_OFF();

		// Need two samples to feed Miller and Manchester-Decoder
		if (sniffCounter & 0x01) {

			// no need to try decoding tag data if the reader is sending
			if (!TagIsActive) {		
				uint8_t readerbyte = (previous_data & 0xF0) | (*data >> 4);
				if (MillerDecoding(readerbyte, (sniffCounter-1)*4)) {
					LogTrace(receivedCmd, uart->len, 0, 0, NULL, true);
					DemodReset();
					UartReset();
				}
				ReaderIsActive = (uart->state != STATE_UNSYNCD);
			}
			
			// no need to try decoding tag data if the reader is sending
			if (!ReaderIsActive) {		
				uint8_t tagbyte = (previous_data << 4) | (*data & 0x0F);
				if (ManchesterDecoding(tagbyte, 0, (sniffCounter-1)*4)) {
					LogTrace(receivedResp,  demod->len, 0, 0, NULL, false);
					DemodReset();
					UartReset();
				}
				TagIsActive = (demod->state != DEMOD_UNSYNCD);
			}
		}
		previous_data = *data;
		sniffCounter++;
		data++;

		if (data == dmaBuf + DMA_BUFFER_SIZE)
			data = dmaBuf;

	} // main cycle
	
	MfSniffEnd();
	switch_off(); 
}

void MfSniffInit(void){
	memset(sniffUID, 0x00, sizeof(sniffUID));
	memset(sniffATQA, 0x00, sizeof(sniffATQA));
	memset(sniffBuf, 0x00, sizeof(sniffBuf));
	sniffSAK = 0;
	sniffUIDType = SNF_UID_4;
	timerData = 0;
}

void MfSniffEnd(void){
	LED_B_ON();
	cmd_send(CMD_ACK,0,0,0,0,0);
	LED_B_OFF();
}

/*
bool RAMFUNC MfSniffLogic(const uint8_t *data, uint16_t len, uint8_t *parity, uint16_t bitCnt, bool reader) {

	// reset on 7-Bit commands from reader
	if (reader && (len == 1) && (bitCnt == 7)) { 		
		sniffState = SNF_INIT;
	}

	
	
	switch (sniffState) {
		case SNF_INIT:{
			// REQA,WUPA or MAGICWUP from reader			
			if ((len == 1) && (reader) && (bitCnt == 7) ) {
				MfSniffInit();
				sniffState = (data[0] == MIFARE_MAGICWUPC1) ? SNF_MAGIC_WUPC2 : SNF_ATQA;
			}
			break;
		}
		case SNF_MAGIC_WUPC2: {
			if ((len == 1) && (reader) && (data[0] == MIFARE_MAGICWUPC2) ) {  
				sniffState = SNF_CARD_IDLE;
			}
			break;
		}
		case SNF_ATQA:{
			// ATQA from tag
			if ((!reader) && (len == 2)) {
				sniffATQA[0] = data[0];
				sniffATQA[1] = data[1];
				sniffState = SNF_UID;
			}
			break;
		}
		case SNF_UID: {
			
			if ( !reader ) break;
			if ( len != 9 ) break;
			if ( !CheckCrc14443(CRC_14443_A, data, 9)) break;
			if ( data[1] != 0x70 ) break;
			
			Dbprintf("[!] UID | %x", data[0]);
			
			if ((data[0] == ISO14443A_CMD_ANTICOLL_OR_SELECT)) {
				// UID_4 - select 4 Byte UID from reader
				memcpy(sniffUID, data+2, 4);
				sniffUIDType = SNF_UID_4;
				sniffState = SNF_SAK;
			} else if ((data[0] == ISO14443A_CMD_ANTICOLL_OR_SELECT_2)) {
				// UID_7 - Select 2nd part of 7 Byte UID

				// get rid of 0x88
				sniffUID[0] = sniffUID[1];
				sniffUID[1] = sniffUID[2];
				sniffUID[2] = sniffUID[3];
				//new uid bytes
				memcpy(sniffUID+3, data+2, 4);
				sniffUIDType = SNF_UID_7;
				sniffState = SNF_SAK;				
			} else if ((data[0] == ISO14443A_CMD_ANTICOLL_OR_SELECT_3)) {
				// UID_10 - Select 3nd part of 10 Byte UID
				// 3+3+4 = 10.
				// get ride of previous 0x88
				sniffUID[3] = sniffUID[4];
				sniffUID[4] = sniffUID[5];
				sniffUID[5] = sniffUID[6];
				// new uid bytes
				memcpy(sniffUID+6, data+2, 4);
				sniffUIDType = SNF_UID_10;
				sniffState = SNF_SAK;
			}
			break;
		}
		case SNF_SAK:{
			// SAK from card?
			if ((!reader) && (len == 3) && (CheckCrc14443(CRC_14443_A, data, 3))) {
				sniffSAK = data[0];
				// CL2 UID part to be expected
				if (( sniffSAK == 0x04) && (sniffUIDType == SNF_UID_4)) {
					sniffState = SNF_UID;
				// CL3 UID part to be expected
				} else if ((sniffSAK == 0x04) && (sniffUIDType == SNF_UID_7)) {
					sniffState = SNF_UID;
				} else {
					// select completed
					sniffState = SNF_CARD_IDLE;
				}
			}
			break;
		}		
		case SNF_CARD_IDLE:{	// trace the card select sequence
			sniffBuf[0] = 0xFF;
			sniffBuf[1] = 0xFF;
			memcpy(sniffBuf + 2, sniffUID, sizeof(sniffUID));
			memcpy(sniffBuf + 12, sniffATQA, sizeof(sniffATQA));
			sniffBuf[14] = sniffSAK;
			sniffBuf[15] = 0xFF;
			sniffBuf[16] = 0xFF;
			LogTrace(sniffBuf, sizeof(sniffBuf), 0, 0, NULL, true);
			sniffState = SNF_CARD_CMD;
		}	// intentionally no break;
		case SNF_CARD_CMD:{	
			LogTrace(data, len, 0, 0, NULL, reader);	
			timerData = GetTickCount();
			break;
		}	
		default:
			sniffState = SNF_INIT;
		break;
	}
	return false;
}
*/

void RAMFUNC MfSniffSend() {
	uint16_t tracelen = BigBuf_get_traceLen();
	uint16_t chunksize = 0;
	int packlen = tracelen;	// total number of bytes to send
	uint8_t *data = BigBuf_get_addr();	
	
	while (packlen > 0) {
		LED_B_ON();
		chunksize = MIN(USB_CMD_DATA_SIZE, packlen); // chunk size 512
		cmd_send(CMD_ACK, 1, tracelen, chunksize, data + tracelen - packlen, chunksize);		
		packlen -= chunksize;
		LED_B_OFF();
	}

	LED_B_ON();
	cmd_send(CMD_ACK, 2, 0, 0, 0, 0);  // 2 == data transfer finished.
	LED_B_OFF();
}