protected void processClientHello(ServerHandshakeState state, byte[] body) throws IOException {
ByteArrayInputStream buf = new ByteArrayInputStream(body);
// TODO Read RFCs for guidance on the expected record layer version number
ProtocolVersion client_version = TlsUtils.readVersion(buf);
if (!client_version.isDTLS()) {
throw new TlsFatalAlert(AlertDescription.illegal_parameter);
}
/*
* Read the client random
*/
byte[] client_random = TlsUtils.readFully(32, buf);
byte[] sessionID = TlsUtils.readOpaque8(buf);
if (sessionID.length > 32) {
throw new TlsFatalAlert(AlertDescription.illegal_parameter);
}
// TODO RFC 4347 has the cookie length restricted to 32, but not in RFC 6347
byte[] cookie = TlsUtils.readOpaque8(buf);
int cipher_suites_length = TlsUtils.readUint16(buf);
if (cipher_suites_length < 2 || (cipher_suites_length & 1) != 0) {
throw new TlsFatalAlert(AlertDescription.decode_error);
}
/*
* NOTE: "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."
*/
state.offeredCipherSuites = TlsUtils.readUint16Array(cipher_suites_length / 2, buf);
int compression_methods_length = TlsUtils.readUint8(buf);
if (compression_methods_length < 1) {
throw new TlsFatalAlert(AlertDescription.illegal_parameter);
}
state.offeredCompressionMethods = TlsUtils.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.
*/
state.clientExtensions = TlsProtocol.readExtensions(buf);
state.serverContext.setClientVersion(client_version);
state.server.notifyClientVersion(client_version);
state.serverContext.getSecurityParameters().clientRandom = client_random;
state.server.notifyOfferedCipherSuites(state.offeredCipherSuites);
state.server.notifyOfferedCompressionMethods(state.offeredCompressionMethods);
/*
* 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(
state.offeredCipherSuites, CipherSuite.TLS_EMPTY_RENEGOTIATION_INFO_SCSV)) {
state.secure_renegotiation = true;
}
/*
* The server MUST check if the "renegotiation_info" extension is included in the
* ClientHello.
*/
byte[] renegExtData =
TlsUtils.getExtensionData(state.clientExtensions, TlsProtocol.EXT_RenegotiationInfo);
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.
*/
state.secure_renegotiation = true;
if (!Arrays.constantTimeAreEqual(
renegExtData, TlsProtocol.createRenegotiationInfo(TlsUtils.EMPTY_BYTES))) {
throw new TlsFatalAlert(AlertDescription.handshake_failure);
}
}
}
state.server.notifySecureRenegotiation(state.secure_renegotiation);
if (state.clientExtensions != null) {
state.server.processClientExtensions(state.clientExtensions);
}
}
protected byte[] generateServerHello(ServerHandshakeState state) throws IOException {
SecurityParameters securityParameters = state.serverContext.getSecurityParameters();
ByteArrayOutputStream buf = new ByteArrayOutputStream();
ProtocolVersion server_version = state.server.getServerVersion();
if (!server_version.isEqualOrEarlierVersionOf(state.serverContext.getClientVersion())) {
throw new TlsFatalAlert(AlertDescription.internal_error);
}
// TODO Read RFCs for guidance on the expected record layer version number
// recordStream.setReadVersion(server_version);
// recordStream.setWriteVersion(server_version);
// recordStream.setRestrictReadVersion(true);
state.serverContext.setServerVersion(server_version);
TlsUtils.writeVersion(state.serverContext.getServerVersion(), buf);
buf.write(securityParameters.getServerRandom());
/*
* The server may return an empty session_id to indicate that the session will not be cached
* and therefore cannot be resumed.
*/
TlsUtils.writeOpaque8(TlsUtils.EMPTY_BYTES, buf);
state.selectedCipherSuite = state.server.getSelectedCipherSuite();
if (!Arrays.contains(state.offeredCipherSuites, state.selectedCipherSuite)
|| state.selectedCipherSuite == CipherSuite.TLS_NULL_WITH_NULL_NULL
|| state.selectedCipherSuite == CipherSuite.TLS_EMPTY_RENEGOTIATION_INFO_SCSV) {
throw new TlsFatalAlert(AlertDescription.internal_error);
}
validateSelectedCipherSuite(state.selectedCipherSuite, AlertDescription.internal_error);
state.selectedCompressionMethod = state.server.getSelectedCompressionMethod();
if (!Arrays.contains(state.offeredCompressionMethods, state.selectedCompressionMethod)) {
throw new TlsFatalAlert(AlertDescription.internal_error);
}
TlsUtils.writeUint16(state.selectedCipherSuite, buf);
TlsUtils.writeUint8(state.selectedCompressionMethod, buf);
state.serverExtensions = state.server.getServerExtensions();
/*
* RFC 5746 3.6. Server Behavior: Initial Handshake
*/
if (state.secure_renegotiation) {
byte[] renegExtData =
TlsUtils.getExtensionData(state.serverExtensions, TlsProtocol.EXT_RenegotiationInfo);
boolean noRenegExt = (null == renegExtData);
if (noRenegExt) {
/*
* Note that sending a "renegotiation_info" extension in response to a ClientHello
* containing only the SCSV is an explicit exception to the prohibition in RFC 5246,
* Section 7.4.1.4, on the server sending unsolicited extensions and is only allowed
* because the client is signaling its willingness to receive the extension via the
* TLS_EMPTY_RENEGOTIATION_INFO_SCSV SCSV.
*/
/*
* If the secure_renegotiation flag is set to TRUE, the server MUST include an empty
* "renegotiation_info" extension in the ServerHello message.
*/
state.serverExtensions =
TlsExtensionsUtils.ensureExtensionsInitialised(state.serverExtensions);
state.serverExtensions.put(
TlsProtocol.EXT_RenegotiationInfo,
TlsProtocol.createRenegotiationInfo(TlsUtils.EMPTY_BYTES));
}
}
if (state.serverExtensions != null) {
state.maxFragmentLength =
evaluateMaxFragmentLengthExtension(
state.clientExtensions, state.serverExtensions, AlertDescription.internal_error);
securityParameters.truncatedHMac =
TlsExtensionsUtils.hasTruncatedHMacExtension(state.serverExtensions);
state.allowCertificateStatus =
TlsUtils.hasExpectedEmptyExtensionData(
state.serverExtensions,
TlsExtensionsUtils.EXT_status_request,
AlertDescription.internal_error);
state.expectSessionTicket =
TlsUtils.hasExpectedEmptyExtensionData(
state.serverExtensions,
TlsProtocol.EXT_SessionTicket,
AlertDescription.internal_error);
TlsProtocol.writeExtensions(buf, state.serverExtensions);
}
return buf.toByteArray();
}
