/// <summary>
/// Create the payload based on the data stored in the properties. Usually called
/// automatically when changing properties, but you might need to call this manually
/// if you modify the list of alternative carrier records directly without using
/// accessor method provided by this class.
/// </summary>
/// <exception cref="NdefException">Thrown if unable to assemble the payload.
/// The exception message contains further details about the issue.</exception>
public void AssemblePayload()
{
if (_handoverVersion == null)
{
throw new NdefException(NdefExceptionMessages.ExHandoverInvalidVersion);
}
// Convert child records to message
var childMsg = new NdefMessage();
if (_handoverAlternativeCarrierRecords != null)
{
childMsg.AddRange(_handoverAlternativeCarrierRecords);
}
if (_handoverErrorRecord != null)
{
childMsg.Add(_handoverErrorRecord);
}
var childBytes = childMsg.ToByteArray();
var newPayload = new byte[childBytes.Length + 1];
// Frist byte: handover version
newPayload[0] = _handoverVersion.Version;
// Rest of the payload: child message containing Alternative Carrier records + Error record
Array.Copy(childBytes, 0, newPayload, 1, childBytes.Length);
_payload = newPayload;
}
/// <summary>
/// Reverse function to parseRecords() - this one takes
/// the information stored in the individual record instances and assembles
/// it into the payload of the base class.
/// </summary>
/// <remarks>
/// As the URI is mandatory, the payload will not be assembled
/// if no URI is defined.
/// </remarks>
/// <returns>Whether assembling the payload was successful.</returns>
private bool AssemblePayload()
{
// Uri is mandatory - don't assemble the payload if it's not set
if (RecordUri == null)
{
return(false);
}
// URI (mandatory)
var message = new NdefMessage {
RecordUri
};
// Title(s) (optional)
if (Titles != null && Titles.Count > 0)
{
message.AddRange(Titles);
}
// Action (optional)
if (ActionInUse())
{
message.Add(_recordAction);
}
// Size (optional)
if (SizeInUse())
{
message.Add(_recordSize);
}
// Mime Type (optional)
if (MimeTypeInUse())
{
message.Add(_recordMimeType);
}
// Image (optional)
if (ImageInUse())
{
message.Add(_recordImage);
}
SetPayloadAndParse(message.ToByteArray(), false);
return(true);
}
/// <summary>
/// Returns the NDEF message parsed from the contents of <paramref name="message"/>.
/// </summary>
/// <remarks>
/// The <paramref name="message"/> parameter is interpreted as the raw message format
/// defined in the NFC Forum specifications.
/// </remarks>
/// <param name="message">Raw byte array containing the NDEF message, which consists
/// of 0 or more NDEF records.</param>
/// <exception cref="NdefException">Thrown if there is an error parsing the NDEF
/// message out of the byte array.</exception>
/// <returns>If parsing was successful, the NDEF message containing 0 or more NDEF
/// records.</returns>
public static NdefMessage FromByteArray(byte[] message)
{
var result = new NdefMessage();
var seenMessageBegin = false;
var seenMessageEnd = false;
var partialChunk = new MemoryStream();
var record = new NdefRecord();
uint i = 0;
while (i < message.Length)
{
//Debug.WriteLine("Parsing byte[] to NDEF message. New record starts at {0}", i);
// Parse flags out of NDEF message header
// The MB flag is a 1-bit field that when set indicates the start of an NDEF message.
bool messageBegin = (message[i] & 0x80) != 0;
// The ME flag is a 1-bit field that when set indicates the end of an NDEF message.
// Note, that in case of a chunked payload, the ME flag is set only in the terminating record chunk of that chunked payload.
bool messageEnd = (message[i] & 0x40) != 0;
// The CF flag is a 1-bit field indicating that this is either the first record chunk or a middle record chunk of a chunked payload.
bool cf = (message[i] & 0x20) != 0;
// The SR flag is a 1-bit field indicating, if set, that the PAYLOAD_LENGTH field is a single octet.
bool sr = (message[i] & 0x10) != 0;
// The IL flag is a 1-bit field indicating, if set, that the ID_LENGTH field is present in the header as a single octet.
// If the IL flag is zero, the ID_LENGTH field is omitted from the record header and the ID field is also omitted from the record.
bool il = (message[i] & 0x08) != 0;
var typeNameFormat = (NdefRecord.TypeNameFormatType)(message[i] & 0x07);
//Debug.WriteLine("ShortRecord: " + (sr ? "yes" : "no"));
//Debug.WriteLine("Id Length present: " + (il ? "yes" : "no"));
if (messageBegin && seenMessageBegin)
{
throw new NdefException(NdefExceptionMessages.ExMessageBeginLate);
}
else if (!messageBegin && !seenMessageBegin)
{
throw new NdefException(NdefExceptionMessages.ExMessageBeginMissing);
}
else if (messageBegin && !seenMessageBegin)
{
seenMessageBegin = true;
}
if (messageEnd && seenMessageEnd)
{
throw new NdefException(NdefExceptionMessages.ExMessageEndLate);
}
else if (messageEnd && !seenMessageEnd)
{
seenMessageEnd = true;
}
if (cf && (typeNameFormat != NdefRecord.TypeNameFormatType.Unchanged) && partialChunk.Length > 0)
{
throw new NdefException(NdefExceptionMessages.ExMessagePartialChunk);
}
// Header length
int headerLength = 1;
headerLength += (sr) ? 1 : 4;
headerLength += (il) ? 1 : 0;
if (i + headerLength >= message.Length)
{
throw new NdefException(NdefExceptionMessages.ExMessageUnexpectedEnd);
}
// Type length
byte typeLength = message[++i];
if ((typeNameFormat == NdefRecord.TypeNameFormatType.Unchanged) && (typeLength != 0))
{
throw new NdefException(NdefExceptionMessages.ExMessageInvalidChunkedType);
}
// Payload length (short record?)
uint payloadLength;
if (sr)
{
// Short record - payload length is a single octet
payloadLength = message[++i];
}
else
{
// No short record - payload length is four octets representing a 32 bit unsigned integer (MSB-first)
payloadLength = (uint)((message[++i]) << 24);
payloadLength |= (uint)((message[++i]) << 16);
payloadLength |= (uint)((message[++i]) << 8);
payloadLength |= (uint)((message[++i]) << 0);
}
// ID length
byte idLength;
idLength = (byte)(il ? message[++i] : 0);
// Total length of content (= type + payload + ID)
uint contentLength = typeLength + payloadLength + idLength;
if (i + contentLength >= message.Length)
{
throw new NdefException(NdefExceptionMessages.ExMessageUnexpectedEnd);
}
if ((typeNameFormat == NdefRecord.TypeNameFormatType.Unchanged) && (idLength != 0))
{
throw new NdefException(NdefExceptionMessages.ExMessageInvalidChunkedId);
}
if (typeNameFormat != NdefRecord.TypeNameFormatType.Unchanged)
{
record.TypeNameFormat = typeNameFormat;
}
// Read type
if (typeLength > 0)
{
record.Type = new byte[typeLength];
Array.Copy(message, (int)(++i), record.Type, 0, typeLength);
i += (uint)typeLength - 1;
}
// Read ID
if (idLength > 0)
{
record.Id = new byte[idLength];
Array.Copy(message, (int)(++i), record.Id, 0, idLength);
i += (uint)idLength - 1;
}
// Read payload
if (payloadLength > 0)
{
var payload = new byte[payloadLength];
Array.Copy(message, (int)(++i), payload, 0, (int)payloadLength);
if (cf)
{
// chunked payload, except last
partialChunk.Write(payload, 0, payload.Length);
}
else if (typeNameFormat == NdefRecord.TypeNameFormatType.Unchanged)
{
// last chunk of chunked payload
partialChunk.Write(payload, 0, payload.Length);
record.Payload = partialChunk.ToArray();
}
else
{
// non-chunked payload
record.Payload = payload;
}
i += payloadLength - 1;
}
if (!cf)
{
// Add record to the message and create a new record for the next loop iteration
result.Add(record);
record = new NdefRecord();
}
if (!cf && seenMessageEnd)
{
break;
}
// move to start of next record
++i;
}
if (!seenMessageBegin && !seenMessageEnd)
{
throw new NdefException(NdefExceptionMessages.ExMessageNoBeginOrEnd);
}
return(result);
}
/// <summary>
/// Returns the NDEF message parsed from the contents of <paramref name="message"/>.
/// </summary>
/// <remarks>
/// The <paramref name="message"/> parameter is interpreted as the raw message format
/// defined in the NFC Forum specifications.
/// </remarks>
/// <param name="message">Raw byte array containing the NDEF message, which consists
/// of 0 or more NDEF records.</param>
/// <exception cref="NdefException">Thrown if there is an error parsing the NDEF
/// message out of the byte array.</exception>
/// <returns>If parsing was successful, the NDEF message containing 0 or more NDEF
/// records.</returns>
public static NdefMessage FromByteArray(byte[] message)
{
var result = new NdefMessage();
var seenMessageBegin = false;
var seenMessageEnd = false;
var partialChunk = new MemoryStream();
var record = new NdefRecord();
uint i = 0;
while (i < message.Length)
{
//Debug.WriteLine("Parsing byte[] to NDEF message. New record starts at {0}", i);
// Parse flags out of NDEF message header
bool messageBegin = (message[i] & 0x80) != 0;
bool messageEnd = (message[i] & 0x40) != 0;
bool cf = (message[i] & 0x20) != 0;
bool sr = (message[i] & 0x10) != 0;
bool il = (message[i] & 0x08) != 0;
var typeNameFormat = (NdefRecord.TypeNameFormatType)(message[i] & 0x07);
Debug.WriteLine("ShortRecord: " + (sr ? "yes" : "no"));
Debug.WriteLine("Id Length present: " + (il ? "yes" : "no"));
if (messageBegin && seenMessageBegin)
{
throw new NdefException("Message Begin Late");
}
else if (!messageBegin && !seenMessageBegin)
{
throw new NdefException("Begin Missing");
}
else if (messageBegin && !seenMessageBegin)
{
seenMessageBegin = true;
}
if (messageEnd && seenMessageEnd)
{
throw new NdefException("End Late");
}
else if (messageEnd && !seenMessageEnd)
{
seenMessageEnd = true;
}
if (cf && (typeNameFormat != NdefRecord.TypeNameFormatType.Unchanged) && partialChunk.Length > 0)
{
throw new NdefException("Partial Chunk");
}
int headerLength = 1;
headerLength += (sr) ? 1 : 4;
headerLength += (il) ? 1 : 0;
if (i + headerLength >= message.Length)
{
throw new NdefException("NdefExceptionMessages.ExMessageUnexpectedEnd");
}
byte typeLength = message[++i];
if ((typeNameFormat == NdefRecord.TypeNameFormatType.Unchanged) && (typeLength != 0))
{
throw new NdefException("Invalid Chunk");
}
uint payloadLength;
if (sr)
{
// Short record - payload length is a single octet
payloadLength = message[++i];
}
else
{
// No short record - payload length is four octets representing a 32 bit unsigned integer (MSB-first)
payloadLength = (uint)((message[++i]) << 24);
payloadLength |= (uint)((message[++i]) << 16);
payloadLength |= (uint)((message[++i]) << 8);
payloadLength |= (uint)((message[++i]) << 0);
}
//Debug.WriteLine("Payload length: " + payloadLength);
byte idLength;
idLength = (byte)(il ? message[++i] : 0);
uint contentLength = typeLength + payloadLength + idLength;
if (i + contentLength >= message.Length)
{
throw new NdefException("Unexpected End");
}
//Debug.WriteLine("Content length: {0} (Start at: {1})", contentLength, i);
if ((typeNameFormat == NdefRecord.TypeNameFormatType.Unchanged) && (idLength != 0))
{
throw new NdefException("Invalid Chunk Id");
}
if (typeNameFormat != NdefRecord.TypeNameFormatType.Unchanged)
{
record.TypeNameFormat = typeNameFormat;
}
if (typeLength > 0)
{
record.Type = new byte[typeLength];
Array.Copy(message, (int)(++i), record.Type, 0, typeLength);
i += (uint)typeLength - 1;
}
if (idLength > 0)
{
record.Id = new byte[idLength];
Array.Copy(message, (int)(++i), record.Id, 0, idLength);
i += (uint)idLength - 1;
}
if (payloadLength > 0)
{
var payload = new byte[payloadLength];
Array.Copy(message, (int)(++i), payload, 0, (int)payloadLength);
if (cf)
{
// chunked payload, except last
partialChunk.Write(payload, 0, payload.Length);
}
else if (typeNameFormat == NdefRecord.TypeNameFormatType.Unchanged)
{
// last chunk of chunked payload
partialChunk.Write(payload, 0, payload.Length);
record.Payload = partialChunk.ToArray();
}
else
{
// non-chunked payload
record.Payload = payload;
}
i += payloadLength - 1;
}
if (!cf)
{
result.Add(record);
record = new NdefRecord();
}
if (!cf && seenMessageEnd)
{
break;
}
// move to start of next record
++i;
}
if (!seenMessageBegin && !seenMessageEnd)
{
throw new NdefException("No Begin Or End");
}
return(result);
}