/**
* Returns a DHCP DISCOVER, INFORM, or REQUEST message that can be sent to the DHCP server. DHCP
* server should respond with a DHCP OFFER, ACK, or NAK message in response..
*
* @param (InetAddress) addr The address to poll
* @param (byte) mType The type of DHCP message to send (DISCOVER, INFORM, or REQUEST)
* @return The message to send to the DHCP server.
*/
private static Message getPollingRequest(InetAddress addr, byte mType) {
int xid = 0;
synchronized (Poller.class) {
xid = ++m_nextXid;
}
DHCPMessage messageOut = new DHCPMessage();
byte[] rawIp = addr.getAddress();
// if targetOffset = true, we don't want to REQUEST the DHCP server's
// own IP, so change it by 1, trying to avoid the subnet address
// and the broadcast address.
if (targetOffset) {
if (rawIp[3] % 2 == 0 && rawIp[3] != 0) {
--rawIp[3];
} else {
++rawIp[3];
}
}
// fill DHCPMessage object
//
messageOut.setOp((byte) 1);
messageOut.setHtype((byte) 1);
messageOut.setHlen((byte) 6);
messageOut.setXid(xid);
messageOut.setSecs((short) 0);
messageOut.setChaddr(s_hwAddress); // set hardware address
if (relayMode) {
messageOut.setHops((byte) 1);
messageOut.setGiaddr(s_myIpAddress); // set relay address for replies
} else {
messageOut.setHops((byte) 0);
messageOut.setFlags(BROADCAST_FLAG);
}
messageOut.setOption(MESSAGE_TYPE, new byte[] {mType});
if (mType == DHCPMessage.REQUEST) {
if (reqTargetIp) {
messageOut.setOption(REQUESTED_IP, rawIp);
messageOut.setCiaddr(rawIp);
} else {
messageOut.setOption(REQUESTED_IP, s_requestIpAddress);
messageOut.setCiaddr(s_requestIpAddress);
}
}
if (mType == DHCPMessage.INFORM) {
messageOut.setOption(REQUESTED_IP, s_myIpAddress);
messageOut.setCiaddr(s_myIpAddress);
}
return new Message(addr, messageOut);
}
private boolean sendMessage(
String status, DHCPMessage outMessage, DHCPSocket socket, int xid, int type) {
outMessage.setOp((byte) 1);
outMessage.setHtype((byte) 1);
outMessage.setHlen((byte) 6);
outMessage.setHops((byte) 0);
outMessage.setXid(xid);
outMessage.setSecs((short) 0);
if (type == 1 || type == 3) {
outMessage.setFlags((short) -32768);
} else {
outMessage.setFlags((short) 0);
}
byte initAddr[] = new byte[4];
for (int i = 0; i < 4; i++) initAddr[i] = 0;
outMessage.setCiaddr(initAddr);
outMessage.setYiaddr(initAddr);
outMessage.setSiaddr(initAddr);
outMessage.setGiaddr(initAddr);
byte mtype[] = new byte[1];
mtype[0] = (byte) type;
outMessage.setOption(53, mtype);
outMessage.setOption(51, intToBytes(1));
try {
socket.send(outMessage);
} catch (IOException ie) {
status = ie.getMessage();
return false;
}
return true;
}
private Object[] acquireAddress(int xid, byte hwaddr[], int sleepTime) {
Object results[] = new Object[5];
results[0] = "n/a";
results[1] = String.valueOf(0);
results[2] = "error";
results[3] = "no data";
results[4] = "no data";
int releaseTime = -1;
DHCPSocket socket = null;
DHCPMessage outMessage = new DHCPMessage();
DHCPMessage replyMessage = new DHCPMessage();
byte offeredAddr[] = new byte[4];
byte backupAddr[] = new byte[4];
Random r = new Random();
if ((socket = openSocket(socket)) == null) {
results[3] = results[4] = lastError;
return results;
}
outMessage.setChaddr(hwaddr);
if (IP.length() > 0) {
outMessage.setOption(50, stringToIP(IP));
}
for (int i = 0; i < 10; i++) {
if (!sendMessage(lastError, outMessage, socket, xid, 1)) {
results[3] = results[4] = lastError;
socket.close();
return results;
}
try {
Thread.sleep(sleepTime);
} catch (InterruptedException e) {
}
if (socket.receive(replyMessage)) {
if (checkOffer(replyMessage, xid)) {
offeredAddr = replyMessage.getYiaddr();
System.arraycopy(offeredAddr, 0, backupAddr, 0, 4);
break;
}
if (unavailable) {
results[3] = results[4] = lastError;
socket.close();
return results;
}
}
if (i == 9) {
results[3] = results[4] = "Timed out waiting for DHCPOFFER";
socket.close();
return results;
}
}
releaseTime = 1;
outMessage.setOption(54, replyMessage.getOption(54));
sendMessage(lastError, outMessage, socket, xid, 3, offeredAddr);
if (!socket.receive(replyMessage)) {
results[3] = results[4] = "Timed out waiting for DHCPACK";
socket.close();
return results;
}
if (replyMessage.getXid() != xid) {
results[3] = results[4] = "Received invalid DHCPACK from server";
socket.close();
return results;
}
try {
Thread.sleep(1000);
} catch (InterruptedException e) {
}
outMessage.setCiaddr(backupAddr);
outMessage.setOption(50, new byte[4]);
outMessage.setOption(51, new byte[4]);
outMessage.setOption(54, replyMessage.getOption(54));
sendMessage(lastError, outMessage, socket, r.nextInt(), 7);
socket.close();
long totalDuration = System.currentTimeMillis() - startTime;
String stateString =
(new StringBuilder()).append("leased address ").append(ipToString(backupAddr)).toString();
String duration = (float) totalDuration / 1000F + " sec";
results[0] = results[1] = duration;
results[2] = "ok";
results[3] =
(new StringBuilder()).append("leased address ").append(ipToString(backupAddr)).toString();
results[4] = stateString;
return results;
}