@Override
@SuppressWarnings("unchecked")
public <T> T getOption(SocketOption<T> name) throws IOException {
if (name == null) throw new NullPointerException();
if (!supportedOptions().contains(name))
throw new UnsupportedOperationException("'" + name + "' not supported");
synchronized (stateLock) {
ensureOpen();
if (name == StandardSocketOptions.IP_TOS) {
// IPv4 only; always return 0 on IPv6
if (family == StandardProtocolFamily.INET) {
return (T) Net.getSocketOption(fd, family, name);
} else {
return (T) Integer.valueOf(0);
}
}
if (name == StandardSocketOptions.IP_MULTICAST_TTL
|| name == StandardSocketOptions.IP_MULTICAST_LOOP) {
return (T) Net.getSocketOption(fd, family, name);
}
if (name == StandardSocketOptions.IP_MULTICAST_IF) {
if (family == StandardProtocolFamily.INET) {
int address = Net.getInterface4(fd);
if (address == 0) return null; // default interface
InetAddress ia = Net.inet4FromInt(address);
NetworkInterface ni = NetworkInterface.getByInetAddress(ia);
if (ni == null) throw new IOException("Unable to map address to interface");
return (T) ni;
} else {
int index = Net.getInterface6(fd);
if (index == 0) return null; // default interface
NetworkInterface ni = NetworkInterface.getByIndex(index);
if (ni == null) throw new IOException("Unable to map index to interface");
return (T) ni;
}
}
// no special handling
return (T) Net.getSocketOption(fd, Net.UNSPEC, name);
}
}