barCodeScanningGun/arduinoLibrary/rc522/NDEF_MFRC522/src/MifareUltralight.cpp

#include <MifareUltralight.h>

MifareUltralight::MifareUltralight(MFRC522 *nfcShield)
{
    nfc = nfcShield;
}

MifareUltralight::~MifareUltralight()
{
}

NfcTag MifareUltralight::read()
{
    if (isUnformatted())
    {
#ifdef NDEF_USE_SERIAL
        Serial.println(F("WARNING: Tag is not formatted."));
#endif
        return NfcTag(nfc->uid.uidByte, nfc->uid.size, NfcTag::TYPE_2);
    }

    uint16_t messageLength = 0;
    uint16_t ndefStartIndex = 0;
    findNdefMessage(&messageLength, &ndefStartIndex);

    uint16_t bufferSize = calculateBufferSize(messageLength, ndefStartIndex);

    if (messageLength == 0) { // data is 0x44 0x03 0x00 0xFE
        NdefMessage message = NdefMessage();
        message.addEmptyRecord();
        return NfcTag(nfc->uid.uidByte, nfc->uid.size, NfcTag::TYPE_2, message);
    }

    uint8_t index = 0;
    byte buffer[bufferSize];
    for (uint8_t page = ULTRALIGHT_DATA_START_PAGE; page < ULTRALIGHT_MAX_PAGE; page+=(ULTRALIGHT_READ_SIZE/ULTRALIGHT_PAGE_SIZE))
    {
        // read the data
        byte dataSize = ULTRALIGHT_READ_SIZE + 2;
        MFRC522::StatusCode status = nfc->MIFARE_Read(page, &buffer[index], &dataSize);
        if (status == MFRC522::STATUS_OK)
        {
            #ifdef MIFARE_ULTRALIGHT_DEBUG
            Serial.print(F("Page "));Serial.print(page);Serial.print(" ");
            PrintHexChar(&buffer[index], ULTRALIGHT_PAGE_SIZE);
            PrintHexChar(&buffer[index+ULTRALIGHT_PAGE_SIZE], ULTRALIGHT_PAGE_SIZE);
            PrintHexChar(&buffer[index+2*ULTRALIGHT_PAGE_SIZE], ULTRALIGHT_PAGE_SIZE);
            PrintHexChar(&buffer[index+3*ULTRALIGHT_PAGE_SIZE], ULTRALIGHT_PAGE_SIZE);
            #endif
        }
        else
        {
#ifdef NDEF_USE_SERIAL
            Serial.print(F("Read failed "));Serial.println(page);
#endif
            return NfcTag(nfc->uid.uidByte, nfc->uid.size, NfcTag::TYPE_2);
        }

        if (index >= (messageLength + ndefStartIndex))
        {
            break;
        }

        index += ULTRALIGHT_READ_SIZE;
    }

    return NfcTag(nfc->uid.uidByte, nfc->uid.size, NfcTag::TYPE_2, &buffer[ndefStartIndex], messageLength);

}

boolean MifareUltralight::isUnformatted()
{
    uint8_t page = 4;
    byte dataSize = ULTRALIGHT_READ_SIZE+2;
    byte data[dataSize];
    MFRC522::StatusCode status = nfc->MIFARE_Read(page, data, &dataSize);
    if (status == MFRC522::STATUS_OK && dataSize >= 4)
    {
        return (data[0] == 0xFF && data[1] == 0xFF && data[2] == 0xFF && data[3] == 0xFF);
    }
    else
    {
#ifdef NDEF_USE_SERIAL
        Serial.print(F("Error. Failed read page "));Serial.println(page);
#endif
        return false;
    }
}

// page 3 has tag capabilities
uint16_t MifareUltralight::readTagSize()
{
    uint16_t tagCapacity = 0;
    byte dataSize = ULTRALIGHT_READ_SIZE+2;
    byte data[dataSize];
    MFRC522::StatusCode status = nfc->MIFARE_Read(3, data, &dataSize);
    if (status == MFRC522::STATUS_OK && dataSize >= 2)
    {
        // See AN1303 - different rules for Mifare Family byte2 = (additional data + 48)/8
        tagCapacity = data[2] * 8;
        #ifdef MIFARE_ULTRALIGHT_DEBUG
        Serial.print(F("Tag capacity "));Serial.print(tagCapacity);Serial.println(F(" bytes"));
        #endif

        // TODO future versions should get lock information
    }

    return tagCapacity;
}

// read enough of the message to find the ndef message length
void MifareUltralight::findNdefMessage(uint16_t *messageLength, uint16_t *ndefStartIndex)
{
    byte dataSize = ULTRALIGHT_READ_SIZE + 2;
    byte data[dataSize]; // 3 pages, but 4 + CRC are returned

    if(nfc->MIFARE_Read(4, data, &dataSize) == MFRC522::STATUS_OK)
    {
        #ifdef MIFARE_ULTRALIGHT_DEBUG
        Serial.println(F("Pages 4-7"));
        PrintHexChar(data, 18);
        PrintHexChar(data+ULTRALIGHT_PAGE_SIZE, 18);
        PrintHexChar(data+2*ULTRALIGHT_PAGE_SIZE, 18);
        PrintHexChar(data+3*ULTRALIGHT_PAGE_SIZE, 18);
        #endif

        if (data[0] == 0x03)
        {
            *messageLength = data[1];
            *ndefStartIndex = 2;
        }
        else if (data[5] == 0x3) // page 5 byte 1
        {
            // TODO should really read the lock control TLV to ensure byte[5] is correct
            *messageLength = data[6];
            *ndefStartIndex = 7;
        }
    }

    #ifdef MIFARE_ULTRALIGHT_DEBUG
    Serial.print(F("messageLength "));Serial.println(*messageLength);
    Serial.print(F("ndefStartIndex "));Serial.println(*ndefStartIndex);
    #endif
}

// buffer is larger than the message, need to handle some data before and after
// message and need to ensure we read full pages
uint16_t MifareUltralight::calculateBufferSize(uint16_t messageLength, uint16_t ndefStartIndex)
{
    // TLV terminator 0xFE is 1 byte
    uint16_t bufferSize = messageLength + ndefStartIndex + 1;

    if (bufferSize % ULTRALIGHT_READ_SIZE != 0)
    {
        // buffer must be an increment of page size
        bufferSize = ((bufferSize / ULTRALIGHT_READ_SIZE) + 1) * ULTRALIGHT_READ_SIZE;
    }

    //MFRC522 also return CRC
    bufferSize += 2;

    return bufferSize;
}

boolean MifareUltralight::write(NdefMessage& m)
{
    if (isUnformatted())
    {
#ifdef NDEF_USE_SERIAL
        Serial.println(F("WARNING: Tag is not formatted."));
#endif
        return false;
    }
    uint16_t tagCapacity = readTagSize(); // meta info for tag

    uint16_t messageLength  = m.getEncodedSize();
    uint16_t ndefStartIndex = messageLength < 0xFF ? 2 : 4;
    uint16_t bufferSize = calculateBufferSize(messageLength, ndefStartIndex);

    if(bufferSize>tagCapacity) {
	    #ifdef MIFARE_ULTRALIGHT_DEBUG
    	Serial.print(F("Encoded Message length exceeded tag Capacity "));Serial.println(tagCapacity);
    	#endif
    	return false;
    }

    uint8_t encoded[bufferSize];
    uint8_t *  src = encoded;
    unsigned int position = 0;
    uint8_t page = ULTRALIGHT_DATA_START_PAGE;

    // Set message size. With ultralight should always be less than 0xFF but who knows?

    encoded[0] = 0x3;
    if (messageLength < 0xFF)
    {
        encoded[1] = messageLength;
    }
    else
    {
        encoded[1] = 0xFF;
        encoded[2] = ((messageLength >> 8) & 0xFF);
        encoded[3] = (messageLength & 0xFF);
    }

    m.encode(encoded+ndefStartIndex);
    // this is always at least 1 byte copy because of terminator.
    memset(encoded+ndefStartIndex+messageLength,0,bufferSize-ndefStartIndex-messageLength);
    encoded[ndefStartIndex+messageLength] = 0xFE; // terminator

    #ifdef MIFARE_ULTRALIGHT_DEBUG
    Serial.print(F("messageLength "));Serial.println(messageLength);
    Serial.print(F("Tag Capacity "));Serial.println(tagCapacity);
    PrintHex(encoded,bufferSize);
    #endif

    while (position < bufferSize){ //bufferSize is always times pagesize so no "last chunk" check
        // Although we have to provide 16 bytes to MIFARE_Write only 4 of them are written onto the tag
        byte writeBuffer[16] = {0};
        memcpy (writeBuffer, src, 4);
        // write page
        if (nfc->MIFARE_Write(page, writeBuffer, 16) != MFRC522::STATUS_OK)
            return false;
		#ifdef MIFARE_ULTRALIGHT_DEBUG
        Serial.print(F("Wrote page "));Serial.print(page);Serial.print(F(" - "));
    	PrintHex(src,ULTRALIGHT_PAGE_SIZE);
    	#endif
        page++;
        src+=ULTRALIGHT_PAGE_SIZE;
        position+=ULTRALIGHT_PAGE_SIZE;
    }
    return true;
}

// Mifare Ultralight can't be reset to factory state
// zero out tag data like the NXP Tag Write Android application
boolean MifareUltralight::clean()
{
    uint16_t tagCapacity = readTagSize();

    uint8_t pages = (tagCapacity / ULTRALIGHT_PAGE_SIZE) + ULTRALIGHT_DATA_START_PAGE;

    // factory tags have 0xFF, but OTP-CC blocks have already been set so we use 0x00
    byte data[16] = { 0 };

    for (int i = ULTRALIGHT_DATA_START_PAGE; i < pages; i++)
    {
        #ifdef MIFARE_ULTRALIGHT_DEBUG
        Serial.print(F("Wrote page "));Serial.print(i);Serial.print(F(" - "));
        PrintHex(data, ULTRALIGHT_PAGE_SIZE);
        #endif
        if (nfc->MIFARE_Write(i, data, 16) != MFRC522::STATUS_OK)
        {
            return false;
        }
    }
    return true;
}