/*
* Get the active protocol versions.
*
* In TLS 1.1, many weak or vulnerable cipher suites were obsoleted,
* such as TLS_RSA_EXPORT_WITH_RC4_40_MD5. The implementation MUST NOT
* negotiate these cipher suites in TLS 1.1 or later mode.
*
* For example, if "TLS_RSA_EXPORT_WITH_RC4_40_MD5" is the
* only enabled cipher suite, the client cannot request TLS 1.1 or
* later, even though TLS 1.1 or later is enabled. We need to create a
* subset of the enabled protocols, called the active protocols, which
* contains protocols appropriate to the list of enabled Ciphersuites.
*
* Return empty list instead of null if no active protocol versions.
*/
ProtocolList getActiveProtocols() {
if (activeProtocols == null) {
ArrayList<ProtocolVersion> protocols = new ArrayList<>(4);
for (ProtocolVersion protocol : enabledProtocols.collection()) {
boolean found = false;
for (CipherSuite suite : enabledCipherSuites.collection()) {
if (suite.isAvailable()
&& suite.obsoleted > protocol.v
&& suite.supported <= protocol.v) {
if (algorithmConstraints.permits(
EnumSet.of(CryptoPrimitive.KEY_AGREEMENT), suite.name, null)) {
protocols.add(protocol);
found = true;
break;
} else if (debug != null && Debug.isOn("verbose")) {
System.out.println("Ignoring disabled cipher suite: " + suite + " for " + protocol);
}
} else if (debug != null && Debug.isOn("verbose")) {
System.out.println("Ignoring unsupported cipher suite: " + suite + " for " + protocol);
}
}
if (!found && (debug != null) && Debug.isOn("handshake")) {
System.out.println("No available cipher suite for " + protocol);
}
}
activeProtocols = new ProtocolList(protocols);
}
return activeProtocols;
}
/**
* Check if the given ciphersuite is enabled and available. Does not check if the required server
* certificates are available.
*/
boolean isNegotiable(CipherSuite s) {
if (activeCipherSuites == null) {
activeCipherSuites = getActiveCipherSuites();
}
return activeCipherSuites.contains(s) && s.isNegotiable();
}
