protected SslHandshakeStatus ProcessClientHello(HandshakeMessage message)
{
if (m_State != HandshakeType.Nothing && m_State != HandshakeType.Finished)
{
throw new SslException(AlertDescription.UnexpectedMessage, "ClientHello message must be the first message or must be preceded by a Finished message.");
}
m_IsNegotiating = true;
UpdateHashes(message, HashUpdate.All); // input message
// process ClientHello
ProtocolVersion pv = new ProtocolVersion(message.fragment[0], message.fragment[1]);
m_MaxClientVersion = pv;
if (CompatibilityLayer.SupportsProtocol(m_Options.Protocol, pv) && pv.GetVersionInt() != GetVersion().GetVersionInt())
{
throw new SslException(AlertDescription.IllegalParameter, "Unknown protocol version of the client.");
}
try {
// extract the time from the client [== 1 uint]
m_ClientTime = new byte[4];
Array.Copy(message.fragment, 2, m_ClientTime, 0, 4);
// extract the random bytes [== 28 bytes]
m_ClientRandom = new byte[28];
Array.Copy(message.fragment, 6, m_ClientRandom, 0, 28);
// extact the session ID [== 0..32 bytes]
int length = message.fragment[34];
if (length > 32)
{
throw new SslException(AlertDescription.IllegalParameter, "The length of the SessionID cannot be more than 32 bytes.");
}
m_SessionID = new byte[length];
Array.Copy(message.fragment, 35, m_SessionID, 0, length);
// extract the available cipher suites
length += 35;
int ciphers_size = message.fragment[length] * 256 + message.fragment[length + 1];
if (ciphers_size < 2 || ciphers_size % 2 != 0)
{
throw new SslException(AlertDescription.IllegalParameter, "The number of ciphers is invalid -or- the cipher length is not even.");
}
byte[] ciphers = new byte[ciphers_size];
Array.Copy(message.fragment, length + 2, ciphers, 0, ciphers_size);
m_EncryptionScheme = CipherSuites.GetCipherSuiteAlgorithm(ciphers, m_Options.AllowedAlgorithms);
// extract the available compression algorithms
length += ciphers_size + 2;
int compressors_size = message.fragment[length];
if (compressors_size == 0)
{
throw new SslException(AlertDescription.IllegalParameter, "No compressor specified.");
}
byte[] compressors = new byte[compressors_size];
Array.Copy(message.fragment, length + 1, compressors, 0, compressors_size);
m_CompressionMethod = CompressionAlgorithm.GetCompressionAlgorithm(compressors, m_Options.AllowedAlgorithms);
} catch (Exception e) {
throw new SslException(e, AlertDescription.InternalError, "The message is invalid.");
}
// create reply
return(GetClientHelloResult());
}
// Thanks to Brandon for notifying us about a bug in this method
public override SslHandshakeStatus ProcessSsl2Hello(byte[] hello)
{
if (m_State != HandshakeType.Nothing)
{
throw new SslException(AlertDescription.UnexpectedMessage, "SSL2 ClientHello message must be the first message.");
}
m_IsNegotiating = true;
m_State = HandshakeType.ClientHello;
UpdateHashes(hello, HashUpdate.All); // input message
// process ClientHello
ProtocolVersion pv = new ProtocolVersion(hello[1], hello[2]);
m_MaxClientVersion = pv;
if (CompatibilityLayer.SupportsProtocol(m_Options.Protocol, pv) && pv.GetVersionInt() != GetVersion().GetVersionInt())
{
throw new SslException(AlertDescription.IllegalParameter, "Unknown protocol version of the client.");
}
int csl = hello[3] * 256 + hello[4]; // cipher spec length
int sidl = hello[5] * 256 + hello[6]; // session id length
int cl = hello[7] * 256 + hello[8]; // challenge length
// process ciphers
byte[] ciphers = new byte[(csl / 3) * 2];
int offset = 10;
for (int i = 0; i < ciphers.Length; i += 2)
{
Array.Copy(hello, offset, ciphers, i, 2);
offset += 3;
}
m_EncryptionScheme = CipherSuites.GetCipherSuiteAlgorithm(ciphers, m_Options.AllowedAlgorithms);
// process session id
m_SessionID = new byte[sidl];
Array.Copy(hello, 9 + csl, m_SessionID, 0, sidl);
// process random data [challenge]
m_ClientTime = new byte[4];
m_ClientRandom = new byte[28];
if (cl <= 28)
{
Array.Copy(hello, 9 + csl + sidl, m_ClientRandom, m_ClientRandom.Length - cl, cl);
}
else
{
Array.Copy(hello, 9 + csl + sidl + (cl - 28), m_ClientRandom, 0, 28);
Array.Copy(hello, 9 + csl + sidl, m_ClientTime, 4 - (cl - 28), cl - 28);
}
m_CompressionMethod = SslAlgorithms.NULL_COMPRESSION;
return(GetClientHelloResult());
}