Configuration flag for disabling session request on login

Although this was mandatory on RFC 3921, RFC 6120/6121 don't even mention this part of the protocol.

Signed-off-by: Daniele Ricci <daniele.athome@gmail.com>

core/src/main/java/org/jivesoftware/smack/ConnectionConfiguration.java

@@ -17,6 +17,7 @@
 
 package org.jivesoftware.smack;
 
+import org.jivesoftware.smack.packet.Session;
 import org.jivesoftware.smack.proxy.ProxyInfo;
 import org.jivesoftware.smack.util.DNSUtil;
 import org.jivesoftware.smack.util.dns.HostAddress;
@@ -77,6 +78,7 @@ public class ConnectionConfiguration implements Cloneable {
     private String resource;
     private boolean sendPresence = true;
     private boolean rosterLoadedAtLogin = true;
+    private boolean legacySessionDisabled = false;
     private SecurityMode securityMode = SecurityMode.enabled;
 
     /**
@@ -449,6 +451,28 @@ public class ConnectionConfiguration implements Cloneable {
         this.rosterLoadedAtLogin = rosterLoadedAtLogin;
     }
 
+    /**
+     * Returns true if a {@link Session} will be requested on login if the server
+     * supports it. Although this was mandatory on RFC 3921, RFC 6120/6121 don't
+     * even mention this part of the protocol.
+     *
+     * @return true if a session has to be requested when logging in.
+     */
+    public boolean isLegacySessionDisabled() {
+        return legacySessionDisabled;
+    }
+
+    /**
+     * Sets if a {@link Session} will be requested on login if the server supports
+     * it. Although this was mandatory on RFC 3921, RFC 6120/6121 don't even
+     * mention this part of the protocol.
+     *
+     * @param legacySessionDisabled if a session has to be requested when logging in.
+     */
+    public void setLegacySessionDisabled(boolean legacySessionDisabled) {
+        this.legacySessionDisabled = legacySessionDisabled;
+    }
+
     /**
      * Returns a CallbackHandler to obtain information, such as the password or
      * principal information during the SASL authentication. A CallbackHandler

core/src/main/java/org/jivesoftware/smack/SASLAuthentication.java

@@ -433,7 +433,7 @@ public class SASLAuthentication {
         Bind response = (Bind) connection.createPacketCollectorAndSend(bindResource).nextResultOrThrow();
         String userJID = response.getJid();
 
-        if (sessionSupported) {
+        if (sessionSupported && !connection.getConfiguration().isLegacySessionDisabled()) {
             Session session = new Session();
             connection.createPacketCollectorAndSend(session).nextResultOrThrow();
         }