/**
* Establishes a new outgoing session to a remote server. If the remote server supports TLS and
* SASL then the new outgoing connection will be secured with TLS and authenticated using SASL.
* However, if TLS or SASL is not supported by the remote server or if an error occured while
* securing or authenticating the connection using SASL then server dialback method will be used.
*
* @param domain the local domain to authenticate with the remote server.
* @param hostname the hostname of the remote server.
* @param port default port to use to establish the connection.
* @return new outgoing session to a remote server.
*/
private static LocalOutgoingServerSession createOutgoingSession(
String domain, String hostname, int port) {
String localDomainName = XMPPServer.getInstance().getServerInfo().getXMPPDomain();
boolean useTLS = JiveGlobals.getBooleanProperty(ConnectionSettings.Server.TLS_ENABLED, true);
RemoteServerConfiguration configuration = RemoteServerManager.getConfiguration(hostname);
if (configuration != null) {
// TODO Use the specific TLS configuration for this remote server
// useTLS = configuration.isTLSEnabled();
}
// Connect to remote server using XMPP 1.0 (TLS + SASL EXTERNAL or TLS + server dialback or
// server dialback)
String realHostname = null;
int realPort = port;
Socket socket = null;
// Get a list of real hostnames to connect to using DNS lookup of the specified hostname
List<DNSUtil.HostAddress> hosts = DNSUtil.resolveXMPPDomain(hostname, port);
for (Iterator<DNSUtil.HostAddress> it = hosts.iterator(); it.hasNext(); ) {
try {
socket = new Socket();
DNSUtil.HostAddress address = it.next();
realHostname = address.getHost();
realPort = address.getPort();
Log.debug(
"LocalOutgoingServerSession: OS - Trying to connect to "
+ hostname
+ ":"
+ port
+ "(DNS lookup: "
+ realHostname
+ ":"
+ realPort
+ ")");
// Establish a TCP connection to the Receiving Server
socket.connect(
new InetSocketAddress(realHostname, realPort), RemoteServerManager.getSocketTimeout());
Log.debug(
"LocalOutgoingServerSession: OS - Plain connection to "
+ hostname
+ ":"
+ port
+ " successful");
break;
} catch (Exception e) {
Log.warn(
"Error trying to connect to remote server: "
+ hostname
+ "(DNS lookup: "
+ realHostname
+ ":"
+ realPort
+ "): "
+ e.toString());
try {
if (socket != null) {
socket.close();
}
} catch (IOException ex) {
Log.debug(
"Additional exception while trying to close socket when connection to remote server failed: "
+ ex.toString());
}
}
}
if (!socket.isConnected()) {
return null;
}
SocketConnection connection = null;
try {
connection =
new SocketConnection(XMPPServer.getInstance().getPacketDeliverer(), socket, false);
// Send the stream header
StringBuilder openingStream = new StringBuilder();
openingStream.append("<stream:stream");
openingStream.append(" xmlns:db=\"jabber:server:dialback\"");
openingStream.append(" xmlns:stream=\"http://etherx.jabber.org/streams\"");
openingStream.append(" xmlns=\"jabber:server\"");
openingStream.append(" from=\"").append(localDomainName).append("\""); // OF-673
openingStream.append(" to=\"").append(hostname).append("\"");
openingStream.append(" version=\"1.0\">");
connection.deliverRawText(openingStream.toString());
// Set a read timeout (of 5 seconds) so we don't keep waiting forever
int soTimeout = socket.getSoTimeout();
socket.setSoTimeout(5000);
XMPPPacketReader reader = new XMPPPacketReader();
reader
.getXPPParser()
.setInput(new InputStreamReader(socket.getInputStream(), StandardCharsets.UTF_8));
// Get the answer from the Receiving Server
XmlPullParser xpp = reader.getXPPParser();
for (int eventType = xpp.getEventType(); eventType != XmlPullParser.START_TAG; ) {
eventType = xpp.next();
}
String serverVersion = xpp.getAttributeValue("", "version");
String id = xpp.getAttributeValue("", "id");
// Check if the remote server is XMPP 1.0 compliant
if (serverVersion != null && decodeVersion(serverVersion)[0] >= 1) {
// Restore default timeout
socket.setSoTimeout(soTimeout);
// Get the stream features
Element features = reader.parseDocument().getRootElement();
if (features != null) {
// Check if TLS is enabled
if (useTLS && features.element("starttls") != null) {
// Secure the connection with TLS and authenticate using SASL
LocalOutgoingServerSession answer;
answer = secureAndAuthenticate(hostname, connection, reader, openingStream, domain);
if (answer != null) {
// Everything went fine so return the secured and
// authenticated connection
return answer;
}
}
// Check if we are going to try server dialback (XMPP 1.0)
else if (ServerDialback.isEnabled() && features.element("dialback") != null) {
Log.debug(
"LocalOutgoingServerSession: OS - About to try connecting using server dialback XMPP 1.0 with: "
+ hostname);
ServerDialback method = new ServerDialback(connection, domain);
OutgoingServerSocketReader newSocketReader = new OutgoingServerSocketReader(reader);
if (method.authenticateDomain(newSocketReader, domain, hostname, id)) {
Log.debug(
"LocalOutgoingServerSession: OS - SERVER DIALBACK XMPP 1.0 with "
+ hostname
+ " was successful");
StreamID streamID = new BasicStreamIDFactory().createStreamID(id);
LocalOutgoingServerSession session =
new LocalOutgoingServerSession(domain, connection, newSocketReader, streamID);
connection.init(session);
// Set the hostname as the address of the session
session.setAddress(new JID(null, hostname, null));
return session;
} else {
Log.debug(
"LocalOutgoingServerSession: OS - Error, SERVER DIALBACK with "
+ hostname
+ " failed");
}
}
} else {
Log.debug("LocalOutgoingServerSession: OS - Error, <starttls> was not received");
}
}
// Something went wrong so close the connection and try server dialback over
// a plain connection
if (connection != null) {
connection.close();
}
} catch (SSLHandshakeException e) {
Log.debug(
"LocalOutgoingServerSession: Handshake error while creating secured outgoing session to remote "
+ "server: "
+ hostname
+ "(DNS lookup: "
+ realHostname
+ ":"
+ realPort
+ "):",
e);
// Close the connection
if (connection != null) {
connection.close();
}
} catch (Exception e) {
Log.error(
"Error creating secured outgoing session to remote server: "
+ hostname
+ "(DNS lookup: "
+ realHostname
+ ":"
+ realPort
+ ")",
e);
// Close the connection
if (connection != null) {
connection.close();
}
}
if (ServerDialback.isEnabled()) {
Log.debug(
"LocalOutgoingServerSession: OS - Going to try connecting using server dialback with: "
+ hostname);
// Use server dialback (pre XMPP 1.0) over a plain connection
return new ServerDialback().createOutgoingSession(domain, hostname, port);
}
return null;
}
/**
* Creates a new outgoing connection to the specified hostname if no one exists. The port of the
* remote server could be configured by setting the <b>xmpp.server.socket.remotePort</b> property
* or otherwise the standard port 5269 will be used. Either a new connection was created or
* already existed the specified hostname will be authenticated with the remote server. Once
* authenticated the remote server will start accepting packets from the specified domain.
*
* <p>The Server Dialback method is currently the only implemented method for server-to-server
* authentication. This implies that the remote server will ask the Authoritative Server to verify
* the domain to authenticate. Most probably this (local) server will act as the Authoritative
* Server. See {@link IncomingServerSession} for more information.
*
* @param domain the local domain to authenticate with the remote server.
* @param hostname the hostname of the remote server.
* @return True if the domain was authenticated by the remote server.
*/
public static OutgoingServerSession authenticateDomain(String domain, String hostname) {
if (hostname == null || hostname.length() == 0 || hostname.trim().indexOf(' ') > -1) {
// Do nothing if the target hostname is empty, null or contains whitespaces
return null;
}
try {
// Check if the remote hostname is in the blacklist
if (!RemoteServerManager.canAccess(hostname)) {
return null;
}
OutgoingServerSession session;
// Check if a session, that is using server dialback, already exists to the desired
// hostname (i.e. remote server). If no one exists then create a new session. The same
// session will be used for the same hostname for all the domains to authenticate
SessionManager sessionManager = SessionManager.getInstance();
if (sessionManager == null) {
// Server is shutting down while we are trying to create a new s2s connection
return null;
}
session = sessionManager.getOutgoingServerSession(hostname);
if (session == null) {
// Try locating if the remote server has previously authenticated with this server
for (IncomingServerSession incomingSession :
sessionManager.getIncomingServerSessions(hostname)) {
for (String otherHostname : incomingSession.getValidatedDomains()) {
session = sessionManager.getOutgoingServerSession(otherHostname);
if (session != null) {
if (session.isUsingServerDialback()) {
// A session to the same remote server but with different hostname
// was found. Use this session.
break;
} else {
session = null;
}
}
}
}
}
if (session == null) {
int port = RemoteServerManager.getPortForServer(hostname);
session = createOutgoingSession(domain, hostname, port);
if (session != null) {
// Add the validated domain as an authenticated domain
session.addAuthenticatedDomain(domain);
// Add the new hostname to the list of names that the server may have
session.addHostname(hostname);
// Notify the SessionManager that a new session has been created
sessionManager.outgoingServerSessionCreated((LocalOutgoingServerSession) session);
return session;
} else {
Log.warn("Fail to connect to {} for {}", hostname, domain);
return null;
}
}
// A session already exists. The session was established using server dialback so
// it is possible to do piggybacking to authenticate more domains
if (session.getAuthenticatedDomains().contains(domain)
&& session.getHostnames().contains(hostname)) {
// Do nothing since the domain has already been authenticated
return session;
}
// A session already exists so authenticate the domain using that session
if (session.authenticateSubdomain(domain, hostname)) return session;
} catch (Exception e) {
Log.error("Error authenticating domain with remote server: " + hostname, e);
}
return null;
}