/// <summary>
/// Deserializes a handshake instance from the specified byte array.
/// </summary>
/// <param name="data">An array of bytes containing handshake data.</param>
/// <returns>An initialized instance of the Handshake class deserialized
/// from the specified byte array.</returns>
/// <exception cref="SerializationException">Thrown if the specified byte
/// array does not contain valid handshake data.</exception>
public static Handshake Deserialize(byte[] data) {
Handshake hs = new Handshake();
using (var ms = new MemoryStream(data)) {
using (var r = new BinaryReader(ms)) {
try {
hs.MessageId = (HandshakeType) r.ReadByte();
hs.MajorVersion = r.ReadByte();
hs.MinorVersion = r.ReadByte();
// The payload size is in network byte order (big endian).
hs.PayloadSize = r.ReadUInt16(true);
} catch (Exception e) {
throw new SerializationException("The specified byte array contains " +
"invalid data.", e);
}
}
}
// According to specification, version _must_ be 1.0
if (hs.MajorVersion != majorVersion || hs.MinorVersion != minorVersion) {
throw new SerializationException("Unexpected handshake version: " +
hs.MajorVersion + "." + hs.MinorVersion);
}
// When the handshake message has a MessageId of HandshakeError, the
// AuthPayload field _must_ have a length of 8 bytes.
if (hs.MessageId == HandshakeType.HandshakeError && hs.PayloadSize != 8) {
throw new SerializationException("Unexpected payload size. Expected " +
"8, but was: " + hs.PayloadSize);
}
return hs;
}
/// <summary>
/// Reads the client's handshake from the specified buffer.
/// </summary>
/// <param name="buffer">A byte array from which the handshake data
/// will be read.</param>
/// <param name="offset">The zero-based index in the buffer at which to
/// begin reading bytes.</param>
/// <param name="count">The number of bytes to read from buffer.</param>
/// <returns>True if the handshake has been read completely, otherwise
/// false.</returns>
bool ReadHandshake(byte[] buffer, int offset, int count) {
// Accumulate data into buffer until 5 bytes have been read.
int read = Math.Min(count, 5 - handshakeData.Length);
handshakeData.Append(buffer, offset, read);
if (handshakeData.Length == 5) {
// We're now expecting the payload data.
state = FilterStreamState.ReadingPayload;
handshake = Handshake.Deserialize(handshakeData.ToArray());
handshakeData.Clear();
// Append rest of buffer to payloadData.
payloadData.Append(buffer, offset + read, count - read);
return true;
}
// We haven't read 5 bytes yet.
return false;
}
/// <summary>
/// Reads the server response from the underlying inner stream.
/// </summary>
void ReadServerResponse() {
// We get a base64-encoded ASCII string back from the server.
string base64 = ReadLine(innerStream);
HandshakeType type = HandshakeType.HandshakeInProgress;
byte[] decoded;
try {
// Strip off "+ " continuation command; IMAP and POP3 both use this syntax
// whereas SMTP uses "334 ".
base64 = Regex.Replace(base64, @"^(\+|334)\s", String.Empty);
decoded = Convert.FromBase64String(base64);
} catch (FormatException) {
// If the server didn't respond with base64-data, something must have gone
// wrong and we should gracefully shut down.
type = HandshakeType.HandshakeError;
decoded = errorCode;
}
// Prepare a new handshake to hand to the NegotiateStream instance.
Handshake hs = new Handshake(type, (ushort) decoded.Length);
receivedData = new ByteBuilder()
.Append(hs.Serialize())
.Append(decoded)
.ToArray();
receivedConsumed = 0;
}