/// <summary>
/// Construct a new packet from the supplied data.
/// </summary>
/// <param name="contentsContainsGarbageByte">
/// True if the "contents" array contains a garbage (padding) byte that should NOT
/// be factored into the Length field of the PUP. This is necessary so we can properly
/// support the Echo protocol; since some PUP tests that check validation require that the
/// PUP be echoed in its entirety (including the supposedly-ignorable "garbage" byte on
/// odd-length PUPs) we need to be able to craft a PUP with one extra byte of content that's
/// otherwise ignored...
///
/// TODO: Update to use Serialization code rather than packing bytes by hand.
/// </param>
///
public PUP(PupType type, byte transportControl, UInt32 id, PUPPort destination, PUPPort source, byte[] contents, bool contentsContainsGarbageByte)
{
_rawData = null;
// Ensure content length is <= 532 bytes. (Technically larger PUPs are allowed,
// but conventionally they are not used and I want to keep things safe.)
if (contents.Length > MAX_PUP_SIZE)
{
throw new InvalidOperationException("PUP size must not exceed 532 bytes.");
}
//
// Sanity check:
// "contentsContainGarbageByte" can ONLY be true if "contents" is of even length
//
if (contentsContainsGarbageByte && (contents.Length % 2) != 0)
{
throw new InvalidOperationException("Odd content length with garbage byte specified.");
}
TransportControl = transportControl;
Type = type;
ID = id;
DestinationPort = destination;
SourcePort = source;
// Ensure contents are an even number of bytes.
int contentLength = (contents.Length % 2) == 0 ? contents.Length : contents.Length + 1;
Contents = new byte[contents.Length];
contents.CopyTo(Contents, 0);
// Length is always the real length of the data (not padded to an even number)
Length = (ushort)(PUP_HEADER_SIZE + PUP_CHECKSUM_SIZE + contents.Length);
// Stuff data into raw array
_rawData = new byte[PUP_HEADER_SIZE + PUP_CHECKSUM_SIZE + contentLength];
//
// Subtract off one byte from the Length value if the contents contain a garbage byte.
// (See header comments for function)
if (contentsContainsGarbageByte)
{
Length--;
}
Helpers.WriteUShort(ref _rawData, Length, 0);
_rawData[2] = TransportControl;
_rawData[3] = (byte)Type;
Helpers.WriteUInt(ref _rawData, ID, 4);
DestinationPort.WriteToArray(ref _rawData, 8);
SourcePort.WriteToArray(ref _rawData, 14);
Array.Copy(Contents, 0, _rawData, 20, Contents.Length);
// Calculate the checksum and stow it
Checksum = CalculateChecksum();
Helpers.WriteUShort(ref _rawData, Checksum, _rawData.Length - 2);
}
/// <summary>
/// Same as above, but with no content (i.e. a zero-byte payload)
/// </summary>
/// <param name="type"></param>
/// <param name="id"></param>
/// <param name="destination"></param>
/// <param name="source"></param>
public PUP(PupType type, UInt32 id, PUPPort destination, PUPPort source) :
this(type, id, destination, source, new byte[0])
{
}
/// <summary>
/// Same as above, no garbage byte.
/// </summary>
/// <param name="type"></param>
/// <param name="id"></param>
/// <param name="destination"></param>
/// <param name="source"></param>
/// <param name="contents"></param>
public PUP(PupType type, UInt32 id, PUPPort destination, PUPPort source, byte[] contents) :
this(type, id, destination, source, contents, false)
{
}
/// <summary>
/// Constructor that assumes a transport control of 0
/// </summary>
/// <param name="type"></param>
/// <param name="id"></param>
/// <param name="destination"></param>
/// <param name="source"></param>
/// <param name="contents"></param>
/// <param name="contentsContainsGarbageByte"></param>
public PUP(PupType type, UInt32 id, PUPPort destination, PUPPort source, byte[] contents, bool contentsContainsGarbageByte) :
this(type, 0, id, destination, source, contents, contentsContainsGarbageByte)
{
}