/**

* Copyright 2013 Ronald W Hoffman

*

* Licensed under the Apache License, Version 2.0 (the "License");

* you may not use this file except in compliance with the License.

* You may obtain a copy of the License at

*

* http://www.apache.org/licenses/LICENSE-2.0

*

* Unless required by applicable law or agreed to in writing, software

* distributed under the License is distributed on an "AS IS" BASIS,

* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.

* See the License for the specific language governing permissions and

* limitations under the License.

*/

package JavaBitcoin;

import java.io.ByteArrayInputStream;

import java.io.EOFException;

import java.io.IOException;

import java.nio.ByteBuffer;

/**

* <p>A 'ping' message is sent to test network connectivity to a node. Upon receiving a ping,

* the node responds with a pong.</p>

*

* <p>Ping Message</p>

* <pre>

* Size Field Description

* ==== ===== ===========

* 8 bytes Nonce Random value

* </pre>

*

* <p>Pong Message</p>

* <pre>

* Size Field Description

* ==== ===== ===========

* 8 bytes Nonce Random value from ping message

* </pre> *

*/

public class PingMessage {

/**

* Send a 'ping' message to a peer

*

* @param peer Destination peer

* @return Message to be sent

*/

public static Message buildPingMessage(Peer peer) {

//

// We will use the current time as the nonce

//

byte[] msgData = new byte[8];

Utils.uint64ToByteArrayLE(System.currentTimeMillis(), msgData, 0);

//

// Build the message

//

ByteBuffer buffer = MessageHeader.buildMessage("ping", msgData);

return new Message(buffer, peer, MessageHeader.PING_CMD);

}

/**

* Process a 'ping' message and return a 'pong' response

*

* @param msg Message

* @param inStream Message data stream

* @throws EOFException End-of-data while processing input stream

* @throws IOException Unable to read input stream

*/

public static void processPingMessage(Message msg, ByteArrayInputStream inStream)

throws EOFException, IOException {

//

// BIP0031 adds the 'pong' message and requires an 8-byte nonce in the 'ping'

// message. If we receive a 'ping' without a payload, we do not return a

// 'pong' since the client has not implemented BIP0031.

//

if (inStream.available() < 8)

return;

byte[] bytes = new byte[8];

inStream.read(bytes);

//

// Build the 'pong' response

//

ByteBuffer buffer = MessageHeader.buildMessage("pong", bytes);

msg.setBuffer(buffer);

msg.setCommand(MessageHeader.PONG_CMD);

}

}