protected SslHandshakeStatus ProcessServerHello(HandshakeMessage message) { if (m_State != HandshakeType.ClientHello && m_State != HandshakeType.HelloRequest) { throw new SslException(AlertDescription.UnexpectedMessage, "ServerHello message must be preceded by a ClientHello message."); } UpdateHashes(message, HashUpdate.All); // input message if (message.fragment.Length < 2 || message.fragment[0] != GetVersion().major || message.fragment[1] != GetVersion().minor) { throw new SslException(AlertDescription.IllegalParameter, "Unknown protocol version of the client."); } try { // extract the time from the client [== 1 uint] m_ServerTime = new byte[4]; Array.Copy(message.fragment, 2, m_ServerTime, 0, 4); // extract the random bytes [== 28 bytes] m_ServerRandom = new byte[28]; Array.Copy(message.fragment, 6, m_ServerRandom, 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 selected cipher suite m_EncryptionScheme = CipherSuites.GetCipherAlgorithmType(message.fragment, 35 + length); // extract the selected compression method m_CompressionMethod = CompressionAlgorithm.GetCompressionAlgorithmType(message.fragment, 37 + length); } catch (Exception e) { throw new SslException(e, AlertDescription.InternalError, "The message is invalid."); } return(new SslHandshakeStatus(SslStatus.MessageIncomplete, null)); }
protected override byte[] GetClientHello() { 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; m_State = HandshakeType.ClientHello; byte[] ciphers = CipherSuites.GetCipherAlgorithmBytes(m_Options.AllowedAlgorithms); byte[] compr = CompressionAlgorithm.GetCompressionAlgorithmBytes(m_Options.AllowedAlgorithms); HandshakeMessage temp = new HandshakeMessage(HandshakeType.ClientHello, new byte[38 + ciphers.Length + compr.Length]); m_ClientTime = GetUnixTime(); m_ClientRandom = new byte[28]; m_RNG.GetBytes(m_ClientRandom); ProtocolVersion pv = CompatibilityLayer.GetMaxProtocol(m_Options.Protocol); temp.fragment[0] = pv.major; temp.fragment[1] = pv.minor; Array.Copy(m_ClientTime, 0, temp.fragment, 2, 4); Array.Copy(m_ClientRandom, 0, temp.fragment, 6, 28); temp.fragment[34] = 0; // do not resume a session, and do not let the other side cache it temp.fragment[35] = (byte)(ciphers.Length / 256); temp.fragment[36] = (byte)(ciphers.Length % 256); Array.Copy(ciphers, 0, temp.fragment, 37, ciphers.Length); temp.fragment[37 + ciphers.Length] = (byte)compr.Length; Array.Copy(compr, 0, temp.fragment, 38 + ciphers.Length, compr.Length); byte[] ret = temp.ToBytes(); UpdateHashes(ret, HashUpdate.All); // client hello message return(m_RecordLayer.EncryptBytes(ret, 0, ret.Length, ContentType.Handshake)); }
protected SslHandshakeStatus ProcessServerHello(HandshakeMessage message) { if (m_State != HandshakeType.ClientHello && m_State != HandshakeType.HelloRequest) { throw new SslException(AlertDescription.UnexpectedMessage, "ServerHello message must be preceded by a ClientHello message."); } UpdateHashes(message, HashUpdate.All); // input message //Violation with tls spec. If remote side uses higher protocol version than your, then we must answer with your highest version //if (message.fragment.Length < 2 || message.fragment[0] != GetVersion().major || message.fragment[1] != GetVersion().minor) //throw new SslException(AlertDescription.IllegalParameter, "Unknown protocol version of the client."); int currentProcessedLen = 2; try { // extract the time from the client [== 1 uint] m_ServerTime = new byte[4]; Buffer.BlockCopy(message.fragment, currentProcessedLen, m_ServerTime, 0, 4); currentProcessedLen += 4; // extract the random bytes [== 28 bytes] m_ServerRandom = new byte[28]; Buffer.BlockCopy(message.fragment, currentProcessedLen, m_ServerRandom, 0, 28); currentProcessedLen += 28; // extact the session ID [== 0..32 bytes] int length = message.fragment[currentProcessedLen++]; if (length > 32) { throw new SslException(AlertDescription.IllegalParameter, "The length of the SessionID cannot be more than 32 bytes."); } m_SessionID = new byte[length]; Buffer.BlockCopy(message.fragment, currentProcessedLen, m_SessionID, 0, length); currentProcessedLen += length; // extract the selected cipher suite m_EncryptionScheme = CipherSuites.GetCipherAlgorithmType(message.fragment, currentProcessedLen); currentProcessedLen += 2; // extract the selected compression method m_CompressionMethod = CompressionAlgorithm.GetCompressionAlgorithmType(message.fragment, currentProcessedLen++); } catch (Exception e) { throw new SslException(e, AlertDescription.InternalError, "The message is invalid."); } if (message.fragment.Length == currentProcessedLen) { return(new SslHandshakeStatus(SslStatus.MessageIncomplete, null)); } this.ProcessExtensions(message.fragment, ref currentProcessedLen, ConnectionEnd.Client); return(new SslHandshakeStatus(SslStatus.MessageIncomplete, null)); }
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()); }
protected void GenerateCiphers(byte[] premaster) { byte[] clientrnd = new byte[32], serverrnd = new byte[32]; byte[] random = new byte[64]; Array.Copy(m_ClientTime, 0, clientrnd, 0, 4); Array.Copy(m_ClientRandom, 0, clientrnd, 4, 28); Array.Copy(m_ServerTime, 0, serverrnd, 0, 4); Array.Copy(m_ServerRandom, 0, serverrnd, 4, 28); m_MasterSecret = GenerateMasterSecret(premaster, clientrnd, serverrnd); m_CipherSuite = CipherSuites.GetCipherSuite(GetProtocol(), m_MasterSecret, clientrnd, serverrnd, m_EncryptionScheme, m_Options.Entity); Array.Clear(premaster, 0, premaster.Length); }
protected SslHandshakeStatus ProcessServerKeyExchange(HandshakeMessage message) { if (m_State != HandshakeType.Certificate) { throw new SslException(AlertDescription.UnexpectedMessage, "ServerKeyExchange message must be preceded by a Certificate message."); } CipherDefinition cd = CipherSuites.GetCipherDefinition(m_EncryptionScheme); if (!cd.Exportable) { throw new SslException(AlertDescription.HandshakeFailure, "The ServerKeyExchange message should not be sent for non-exportable ciphers."); } if (m_RemoteCertificate.GetPublicKeyLength() <= 512) { throw new SslException(AlertDescription.HandshakeFailure, "The ServerKeyExchange message should not be sent because the server certificate public key is of exportable length."); } UpdateHashes(message, HashUpdate.All); // input message // extract modulus and exponent RSAParameters pars = new RSAParameters(); int size = message.fragment[0] * 256 + message.fragment[1]; pars.Modulus = new byte[size]; Buffer.BlockCopy(message.fragment, 2, pars.Modulus, 0, size); int offset = size + 2; size = message.fragment[offset] * 256 + message.fragment[offset + 1]; pars.Exponent = new byte[size]; Buffer.BlockCopy(message.fragment, offset + 2, pars.Exponent, 0, size); offset += size + 2; pars.Modulus = RemoveLeadingZeros(pars.Modulus); pars.Exponent = RemoveLeadingZeros(pars.Exponent); m_KeyCipher = new RSACryptoServiceProvider(); m_KeyCipher.ImportParameters(pars); // compute verification hashes MD5SHA1CryptoServiceProvider ms = new MD5SHA1CryptoServiceProvider(); ms.TransformBlock(m_ClientTime, 0, m_ClientTime.Length, m_ClientTime, 0); ms.TransformBlock(m_ClientRandom, 0, m_ClientRandom.Length, m_ClientRandom, 0); ms.TransformBlock(m_ServerTime, 0, m_ServerTime.Length, m_ServerTime, 0); ms.TransformBlock(m_ServerRandom, 0, m_ServerRandom.Length, m_ServerRandom, 0); ms.TransformFinalBlock(message.fragment, 0, offset); // verify the signature size = message.fragment[offset] * 256 + message.fragment[offset + 1]; byte[] signature = new byte[size]; // holds the signature returned by the server Buffer.BlockCopy(message.fragment, offset + 2, signature, 0, size); if (!ms.VerifySignature(m_RemoteCertificate, signature)) { throw new SslException(AlertDescription.HandshakeFailure, "The data was not signed by the server certificate."); } ms.Clear(); return(new SslHandshakeStatus(SslStatus.MessageIncomplete, null)); }
// 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()); }
protected override byte[] GetClientHello() { 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; m_State = HandshakeType.ClientHello; byte[] ciphers = CipherSuites.GetCipherAlgorithmBytes(m_Options.AllowedAlgorithms); byte[] compr = CompressionAlgorithm.GetCompressionAlgorithmBytes(m_Options.AllowedAlgorithms); MemoryStream clientHello = new MemoryStream(); m_ClientTime = GetUnixTime(); m_ClientRandom = new byte[28]; m_RNG.GetBytes(m_ClientRandom); ProtocolVersion pv = CompatibilityLayer.GetMaxProtocol(m_Options.Protocol); clientHello.WriteByte(pv.major); clientHello.WriteByte(pv.minor); clientHello.Write(m_ClientTime, 0, m_ClientTime.Length); clientHello.Write(m_ClientRandom, 0, m_ClientRandom.Length); clientHello.WriteByte(0); clientHello.WriteByte((byte)(ciphers.Length / 256)); clientHello.WriteByte((byte)(ciphers.Length % 256)); clientHello.Write(ciphers, 0, ciphers.Length); clientHello.WriteByte((byte)compr.Length); clientHello.Write(compr, 0, compr.Length); if (this.clientHelloExts != null) { this.clientHelloExts.WriteExtensions(clientHello, ConnectionEnd.Client); } HandshakeMessage hm = new HandshakeMessage(HandshakeType.ClientHello, clientHello.ToArray()); byte[] ret = hm.ToBytes(); UpdateHashes(ret, HashUpdate.All); // client hello message return(m_RecordLayer.EncryptBytes(ret, 0, ret.Length, ContentType.Handshake)); }
protected SslHandshakeStatus ProcessCertificateRequest(HandshakeMessage message) { if (m_State == HandshakeType.ServerKeyExchange) { CipherDefinition cd = CipherSuites.GetCipherDefinition(m_EncryptionScheme); if (this.m_RemoteCertificate.GetPublicKeyLength() <= 512 || !cd.Exportable) { throw new SslException(AlertDescription.HandshakeFailure, "Invalid message."); } } else if (m_State != HandshakeType.Certificate) { throw new SslException(AlertDescription.UnexpectedMessage, "CertificateRequest message must be preceded by a Certificate or ServerKeyExchange message."); } UpdateHashes(message, HashUpdate.All); // input message // get supported certificate types bool supportsRsaCerts = false; byte[] certTypes = new byte[message.fragment[0]]; // currently we're not doing anything with the supported certificate types Buffer.BlockCopy(message.fragment, 1, certTypes, 0, certTypes.Length); for (int i = 0; i < certTypes.Length; i++) { if (certTypes[i] == 1) // rsa_sign { supportsRsaCerts = true; break; } } // get list of distinguished names if (m_Options.RequestHandler != null && supportsRsaCerts) // make sure the client passed a delegate { Queue q = new Queue(); DistinguishedNameList r = new DistinguishedNameList(); int size, offset = message.fragment[0] + 3; byte[] buffer; while (offset < message.fragment.Length) { size = message.fragment[offset] * 256 + message.fragment[offset + 1]; buffer = new byte[size]; Buffer.BlockCopy(message.fragment, offset + 2, buffer, 0, size); q.Enqueue(buffer); offset += size + 2; } // decode RDN structures while (q.Count > 0) { r.Add(ProcessName((byte[])q.Dequeue())); } RequestEventArgs e = new RequestEventArgs(); try { m_Options.RequestHandler(Parent, r, e); if (e.Certificate != null) { m_Options.Certificate = e.Certificate; } } catch (Exception de) { throw new SslException(de, AlertDescription.InternalError, "The code in the CertRequestEventHandler delegate threw an error."); } } if (!supportsRsaCerts) { m_Options.Certificate = null; // do not send client certificate } m_MutualAuthentication = true; return(new SslHandshakeStatus(SslStatus.MessageIncomplete, null)); }
protected SslHandshakeStatus GetClientHelloResult() { MemoryStream retMessage = new MemoryStream(); SslHandshakeStatus ret = new SslHandshakeStatus(); HandshakeMessage temp; byte[] bytes; // ServerHello message temp = new HandshakeMessage(HandshakeType.ServerHello, new byte[38]); m_ServerTime = GetUnixTime(); m_ServerRandom = new byte[28]; m_RNG.GetBytes(m_ServerRandom); temp.fragment[0] = GetVersion().major; temp.fragment[1] = GetVersion().minor; Array.Copy(m_ServerTime, 0, temp.fragment, 2, 4); Array.Copy(m_ServerRandom, 0, temp.fragment, 6, 28); temp.fragment[34] = 0; // do not resume a session, and do not let the other side cache it Array.Copy(CipherSuites.GetCipherAlgorithmBytes(m_EncryptionScheme), 0, temp.fragment, 35, 2); temp.fragment[37] = CompressionAlgorithm.GetAlgorithmByte(m_CompressionMethod); bytes = temp.ToBytes(); retMessage.Write(bytes, 0, bytes.Length); // Certificate message byte[] certs = GetCertificateList(m_Options.Certificate); temp.type = HandshakeType.Certificate; temp.fragment = certs; bytes = temp.ToBytes(); retMessage.Write(bytes, 0, bytes.Length); // ServerKeyExchange message [optional] => only with RSA_EXPORT and public key > 512 bits if (m_Options.Certificate.GetPublicKeyLength() > 512 && CipherSuites.GetCipherDefinition(m_EncryptionScheme).Exportable) { MemoryStream kes = new MemoryStream(); MD5SHA1CryptoServiceProvider mscsp = new MD5SHA1CryptoServiceProvider(); // hash the client and server random values mscsp.TransformBlock(m_ClientTime, 0, 4, m_ClientTime, 0); mscsp.TransformBlock(m_ClientRandom, 0, 28, m_ClientRandom, 0); mscsp.TransformBlock(m_ServerTime, 0, 4, m_ServerTime, 0); mscsp.TransformBlock(m_ServerRandom, 0, 28, m_ServerRandom, 0); // create a new 512 bit RSA key m_KeyCipher = new RSACryptoServiceProvider(512); RSAParameters p = m_KeyCipher.ExportParameters(false); // write the key parameters to the output stream bytes = new byte[] { (byte)(p.Modulus.Length / 256), (byte)(p.Modulus.Length % 256) }; kes.Write(bytes, 0, 2); kes.Write(p.Modulus, 0, p.Modulus.Length); mscsp.TransformBlock(bytes, 0, 2, bytes, 0); mscsp.TransformBlock(p.Modulus, 0, p.Modulus.Length, p.Modulus, 0); bytes = new byte[] { (byte)(p.Exponent.Length / 256), (byte)(p.Exponent.Length % 256) }; kes.Write(bytes, 0, 2); kes.Write(p.Exponent, 0, p.Exponent.Length); mscsp.TransformBlock(bytes, 0, 2, bytes, 0); mscsp.TransformFinalBlock(p.Exponent, 0, p.Exponent.Length); // create signature bytes = mscsp.CreateSignature(m_Options.Certificate); kes.Write(new byte[] { (byte)(bytes.Length / 256), (byte)(bytes.Length % 256) }, 0, 2); kes.Write(bytes, 0, bytes.Length); // write to output temp.type = HandshakeType.ServerKeyExchange; temp.fragment = kes.ToArray(); bytes = temp.ToBytes(); retMessage.Write(bytes, 0, bytes.Length); kes.Close(); } else { m_KeyCipher = (RSACryptoServiceProvider)m_Options.Certificate.PrivateKey; } // CertificateRequest message [optional] if (m_MutualAuthentication) { bytes = GetDistinguishedNames(); if (bytes.Length != 0) // make sure at least one certificate is returned { temp.type = HandshakeType.CertificateRequest; temp.fragment = new byte[bytes.Length + 4]; temp.fragment[0] = 1; // one certificate type supported temp.fragment[1] = 1; // cert type RSA temp.fragment[2] = (byte)(bytes.Length / 256); temp.fragment[3] = (byte)(bytes.Length % 256); Array.Copy(bytes, 0, temp.fragment, 4, bytes.Length); bytes = temp.ToBytes(); retMessage.Write(bytes, 0, bytes.Length); } } // ServerHelloDone message temp.type = HandshakeType.ServerHelloDone; temp.fragment = new byte[0]; bytes = temp.ToBytes(); retMessage.Write(bytes, 0, bytes.Length); // final adjustments ret.Status = SslStatus.ContinueNeeded; ret.Message = retMessage.ToArray(); retMessage.Close(); UpdateHashes(ret.Message, HashUpdate.All); // output message ret.Message = m_RecordLayer.EncryptBytes(ret.Message, 0, ret.Message.Length, ContentType.Handshake); return(ret); }
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."); } Alert alert = null; m_IsNegotiating = true; UpdateHashes(message, HashUpdate.All); // input message // process ClientHello int currentLen = 0; ProtocolVersion pv = new ProtocolVersion(message.fragment[currentLen++], message.fragment[currentLen++]); m_MaxClientVersion = pv; //Violation with tls spec. If remote side uses higher protocol version than your, then we must answer with your highest version //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]; Buffer.BlockCopy(message.fragment, currentLen, m_ClientTime, 0, 4); currentLen += 4; // extract the random bytes [== 28 bytes] m_ClientRandom = new byte[28]; Buffer.BlockCopy(message.fragment, currentLen, m_ClientRandom, 0, 28); currentLen += 28; // extact the session ID [== 0..32 bytes] byte length = message.fragment[currentLen++]; if (length > 32) { throw new SslException(AlertDescription.IllegalParameter, "The length of the SessionID cannot be more than 32 bytes."); } m_SessionID = new byte[length]; Buffer.BlockCopy(message.fragment, currentLen, m_SessionID, 0, length); currentLen += length; // extract the available cipher suites Int16 ciphers_size = BinaryHelper.Int16FromBytes(message.fragment[currentLen++], message.fragment[currentLen++]);//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]; Buffer.BlockCopy(message.fragment, currentLen, ciphers, 0, ciphers_size); currentLen += ciphers_size; m_EncryptionScheme = CipherSuites.GetCipherSuiteAlgorithm(ciphers, m_Options.AllowedAlgorithms); // extract the available compression algorithms int compressors_size = message.fragment[currentLen++]; if (compressors_size == 0) { throw new SslException(AlertDescription.IllegalParameter, "No compressor specified."); } byte[] compressors = new byte[compressors_size]; Buffer.BlockCopy(message.fragment, currentLen, compressors, 0, compressors_size); m_CompressionMethod = CompressionAlgorithm.GetCompressionAlgorithm(compressors, m_Options.AllowedAlgorithms); currentLen += compressors_size; try { if (message.fragment.Length > currentLen) { this.ProcessExtensions(message.fragment, ref currentLen, ConnectionEnd.Server); } } catch (ALPNCantSelectProtocolException ex) { alert = new Alert(ex.Description, ex.Level); } } catch (Exception e) { throw new SslException(e, AlertDescription.InternalError, "The message is invalid."); } // create reply return(GetClientHelloResult(alert)); }