protected virtual void ReceiveClientHelloMessage(MemoryStream buf) { ProtocolVersion client_version = TlsUtilities.ReadVersion(buf); mRecordStream.SetWriteVersion(client_version); if (client_version.IsDtls) { throw new TlsFatalAlert(AlertDescription.illegal_parameter); } byte[] client_random = TlsUtilities.ReadFully(32, buf); /* * TODO RFC 5077 3.4. If a ticket is presented by the client, the server MUST NOT attempt to * use the Session ID in the ClientHello for stateful session resumption. */ byte[] sessionID = TlsUtilities.ReadOpaque8(buf); if (sessionID.Length > 32) { throw new TlsFatalAlert(AlertDescription.illegal_parameter); } /* * TODO RFC 5246 7.4.1.2. If the session_id field is not empty (implying a session * resumption request), this vector MUST include at least the cipher_suite from that * session. */ int cipher_suites_length = TlsUtilities.ReadUint16(buf); if (cipher_suites_length < 2 || (cipher_suites_length & 1) != 0) { throw new TlsFatalAlert(AlertDescription.decode_error); } this.mOfferedCipherSuites = TlsUtilities.ReadUint16Array(cipher_suites_length / 2, buf); /* * TODO RFC 5246 7.4.1.2. If the session_id field is not empty (implying a session * resumption request), it MUST include the compression_method from that session. */ int compression_methods_length = TlsUtilities.ReadUint8(buf); if (compression_methods_length < 1) { throw new TlsFatalAlert(AlertDescription.illegal_parameter); } this.mOfferedCompressionMethods = TlsUtilities.ReadUint8Array(compression_methods_length, buf); /* * TODO RFC 3546 2.3 If [...] the older session is resumed, then the server MUST ignore * extensions appearing in the client hello, and Send a server hello containing no * extensions. */ this.mClientExtensions = ReadExtensions(buf); /* * TODO[session-hash] * * draft-ietf-tls-session-hash-04 4. Clients and servers SHOULD NOT accept handshakes * that do not use the extended master secret [..]. (and see 5.2, 5.3) */ this.mSecurityParameters.extendedMasterSecret = TlsExtensionsUtilities.HasExtendedMasterSecretExtension(mClientExtensions); ContextAdmin.SetClientVersion(client_version); mTlsServer.NotifyClientVersion(client_version); mTlsServer.NotifyFallback(Arrays.Contains(mOfferedCipherSuites, CipherSuite.TLS_FALLBACK_SCSV)); mSecurityParameters.clientRandom = client_random; mTlsServer.NotifyOfferedCipherSuites(mOfferedCipherSuites); mTlsServer.NotifyOfferedCompressionMethods(mOfferedCompressionMethods); /* * RFC 5746 3.6. Server Behavior: Initial Handshake */ { /* * RFC 5746 3.4. The client MUST include either an empty "renegotiation_info" extension, * or the TLS_EMPTY_RENEGOTIATION_INFO_SCSV signaling cipher suite value in the * ClientHello. Including both is NOT RECOMMENDED. */ /* * When a ClientHello is received, the server MUST check if it includes the * TLS_EMPTY_RENEGOTIATION_INFO_SCSV SCSV. If it does, set the secure_renegotiation flag * to TRUE. */ if (Arrays.Contains(mOfferedCipherSuites, CipherSuite.TLS_EMPTY_RENEGOTIATION_INFO_SCSV)) { this.mSecureRenegotiation = true; } /* * The server MUST check if the "renegotiation_info" extension is included in the * ClientHello. */ byte[] renegExtData = TlsUtilities.GetExtensionData(mClientExtensions, ExtensionType.renegotiation_info); if (renegExtData != null) { /* * If the extension is present, set secure_renegotiation flag to TRUE. The * server MUST then verify that the length of the "renegotiated_connection" * field is zero, and if it is not, MUST abort the handshake. */ this.mSecureRenegotiation = true; if (!Arrays.ConstantTimeAreEqual(renegExtData, CreateRenegotiationInfo(TlsUtilities.EmptyBytes))) { throw new TlsFatalAlert(AlertDescription.handshake_failure); } } } mTlsServer.NotifySecureRenegotiation(this.mSecureRenegotiation); if (mClientExtensions != null) { mTlsServer.ProcessClientExtensions(mClientExtensions); } }
protected virtual void SendClientHelloMessage() { this.mRecordStream.SetWriteVersion(this.mTlsClient.ClientHelloRecordLayerVersion); ProtocolVersion client_version = this.mTlsClient.ClientVersion; if (client_version.IsDtls) { throw new TlsFatalAlert(AlertDescription.internal_error); } ContextAdmin.SetClientVersion(client_version); /* * TODO RFC 5077 3.4. When presenting a ticket, the client MAY generate and include a * Session ID in the TLS ClientHello. */ byte[] session_id = TlsUtilities.EmptyBytes; if (this.mTlsSession != null) { session_id = this.mTlsSession.SessionID; if (session_id == null || session_id.Length > 32) { session_id = TlsUtilities.EmptyBytes; } } bool fallback = this.mTlsClient.IsFallback; this.mOfferedCipherSuites = this.mTlsClient.GetCipherSuites(); this.mOfferedCompressionMethods = this.mTlsClient.GetCompressionMethods(); if (session_id.Length > 0 && this.mSessionParameters != null) { if (!Arrays.Contains(this.mOfferedCipherSuites, mSessionParameters.CipherSuite) || !Arrays.Contains(this.mOfferedCompressionMethods, mSessionParameters.CompressionAlgorithm)) { session_id = TlsUtilities.EmptyBytes; } } this.mClientExtensions = this.mTlsClient.GetClientExtensions(); HandshakeMessage message = new HandshakeMessage(HandshakeType.client_hello); TlsUtilities.WriteVersion(client_version, message); message.Write(this.mSecurityParameters.ClientRandom); TlsUtilities.WriteOpaque8(session_id, message); // Cipher Suites (and SCSV) { /* * RFC 5746 3.4. The client MUST include either an empty "renegotiation_info" extension, * or the TLS_EMPTY_RENEGOTIATION_INFO_SCSV signaling cipher suite value in the * ClientHello. Including both is NOT RECOMMENDED. */ byte[] renegExtData = TlsUtilities.GetExtensionData(mClientExtensions, ExtensionType.renegotiation_info); bool noRenegExt = (null == renegExtData); bool noRenegScsv = !Arrays.Contains(mOfferedCipherSuites, CipherSuite.TLS_EMPTY_RENEGOTIATION_INFO_SCSV); if (noRenegExt && noRenegScsv) { // TODO Consider whether to default to a client extension instead // this.mClientExtensions = TlsExtensionsUtilities.EnsureExtensionsInitialised(this.mClientExtensions); // this.mClientExtensions[ExtensionType.renegotiation_info] = CreateRenegotiationInfo(TlsUtilities.EmptyBytes); this.mOfferedCipherSuites = Arrays.Append(mOfferedCipherSuites, CipherSuite.TLS_EMPTY_RENEGOTIATION_INFO_SCSV); } /* * draft-ietf-tls-downgrade-scsv-00 4. If a client sends a ClientHello.client_version * containing a lower value than the latest (highest-valued) version supported by the * client, it SHOULD include the TLS_FALLBACK_SCSV cipher suite value in * ClientHello.cipher_suites. */ if (fallback && !Arrays.Contains(mOfferedCipherSuites, CipherSuite.TLS_FALLBACK_SCSV)) { this.mOfferedCipherSuites = Arrays.Append(mOfferedCipherSuites, CipherSuite.TLS_FALLBACK_SCSV); } TlsUtilities.WriteUint16ArrayWithUint16Length(mOfferedCipherSuites, message); } TlsUtilities.WriteUint8ArrayWithUint8Length(mOfferedCompressionMethods, message); if (mClientExtensions != null) { WriteExtensions(message, mClientExtensions); } message.WriteToRecordStream(this); }