/**
* Pings a peer to test if it's still alive, and sends a list of peers that have disconnected.
*
* @throws IOException In case an unexpected error happens while reading connections
*/
public void ping(RemoteDevice peer) throws IOException {
try {
Socket peerSocket = new Socket();
peerSocket.connect(new InetSocketAddress(peer.getIpAddress(), peer.getPort()), 5000);
DataInputStream in = new DataInputStream(peerSocket.getInputStream());
DataOutputStream out = new DataOutputStream(peerSocket.getOutputStream());
/* The tracker will use the special ID -2 */
out.writeInt(-2);
out.writeInt(serverPort);
/* We prepare the list of peers that have been disconnected */
String message = "";
ArrayList<RemoteDevice> disPeersCopy = new ArrayList<RemoteDevice>(disPeers);
for (RemoteDevice opeer : disPeersCopy) {
message += opeer.getId() + "|";
}
if (message.length() > 0) {
message = message.substring(0, message.length() - 1);
}
/* We send the reply */
out.writeInt(0);
out.writeUTF("ping");
out.writeUTF("pong" + message);
/* We clear the notifying list if everyone has been notified */
notPeers++;
if (notPeers >= peers.size()) {
disPeers = new ArrayList<RemoteDevice>();
notPeers = 0;
}
try {
peerSocket.close();
} catch (IOException ioe) {
System.err.println("IOException while closing peer " + ioe.getMessage());
}
/* The peer appears to be disconnected, remove it from the peerlist */
} catch (SocketTimeoutException ste) {
System.out.println("Peer " + peer.getId() + " is no longer responding.");
peers.remove(peer);
disPeers.add(peer);
notPeers = 0;
} catch (UnknownHostException uhe) {
System.err.println("Unknown host: " + peer.getIpAddress());
} catch (IOException ioe) {
System.out.println("Peer " + peer.getId() + " is no longer responding.");
peers.remove(peer);
disPeers.add(peer);
notPeers = 0;
}
}
/**
* The listen method for the servicing new peers.
*
* @throws IOException In case an unexpected error happens while reading connections
*/
public void listen() throws IOException {
int id = 0;
ServerSocket listenSocket = new ServerSocket(serverPort);
while (true) {
Socket clientSocket = listenSocket.accept();
clientSocket.setSoTimeout(5000);
DataInputStream in = new DataInputStream(clientSocket.getInputStream());
DataOutputStream out = new DataOutputStream(clientSocket.getOutputStream());
try {
String ipAddress = clientSocket.getInetAddress().getHostAddress();
/* Ask peer which port will it use for the P2P communication */
int assignedPort = in.readInt();
/* Assign an id to peer, send it and close connection */
id++;
out.writeInt(id);
RemoteDevice newClient = new RemoteDevice(id, ipAddress, assignedPort);
/* Send the peer list */
ArrayList<RemoteDevice> peersCopy = new ArrayList<RemoteDevice>(peers);
for (RemoteDevice peer : peersCopy) {
out.writeBoolean(true);
out.writeInt(peer.getId());
out.writeUTF(peer.getIpAddress());
out.writeInt(peer.getPort());
}
out.writeBoolean(false);
/* Add new peer to peer list */
getPeers().add(newClient);
} catch (SocketTimeoutException ste) {
System.err.println(
"Socket timeout from peer: " + clientSocket.getInetAddress().getHostAddress());
} catch (IOException ioe) {
System.err.println(
"IOE exception while initializing peer: "
+ clientSocket.getInetAddress().getHostAddress());
} finally {
clientSocket.close();
}
}
}
