/**
* Sends a message to a single server and waits for a response. No checking is done to ensure that
* the response is associated with the query.
*
* @param query The query to send.
* @return The response.
* @throws IOException An error occurred while sending or receiving.
*/
public Message send(Message query) throws IOException {
if (Options.check("verbose"))
System.err.println(
"Sending to " + address.getAddress().getHostAddress() + ":" + address.getPort());
if (query.getHeader().getOpcode() == Opcode.QUERY) {
Record question = query.getQuestion();
if (question != null && question.getType() == Type.AXFR) return sendAXFR(query);
}
query = (Message) query.clone();
applyEDNS(query);
if (tsig != null) {
tsig.apply(query, null);
}
byte[] out = query.toWire(Message.MAXLENGTH);
int udpSize = maxUDPSize(query);
boolean tcp = false;
long endTime = System.currentTimeMillis() + timeoutValue;
do {
byte[] b_in;
if (useTCP || out.length > udpSize) {
tcp = true;
}
if (tcp) {
b_in = TCPClient.sendrecv(localAddress, address, out, endTime);
} else {
b_in = UDPClient.sendrecv(localAddress, address, out, udpSize, endTime);
}
/*
* Check that the response is long enough.
*/
if (b_in.length < Header.LENGTH) {
throw new WireParseException("invalid DNS header - " + "too short");
}
/*
* Check that the response ID matches the query ID. We want
* to check this before actually parsing the message, so that
* if there's a malformed response that's not ours, it
* doesn't confuse us.
*/
int id = ((b_in[0] & 0xFF) << 8) + (b_in[1] & 0xFF);
int qid = query.getHeader().getID();
if (id != qid) {
String error = "invalid message id: expected " + qid + "; got id " + id;
if (tcp) {
throw new WireParseException(error);
} else {
if (Options.check("verbose")) {
System.err.println(error);
}
continue;
}
}
Message response = parseMessage(b_in);
verifyTSIG(query, response, b_in, tsig);
if (!tcp && !ignoreTruncation && response.getHeader().getFlag(Flags.TC)) {
tcp = true;
continue;
}
return response;
} while (true);
}
private void verifyTSIG(Message query, Message response, byte[] b, TSIG tsig) {
if (tsig == null) return;
int error = tsig.verify(response, b, query.getTSIG());
if (Options.check("verbose")) System.err.println("TSIG verify: " + Rcode.TSIGstring(error));
}