[core] Increase resilience against faulty parser implementions

If one of the parser throws a NullPointerException or
NumberFormatException, then this should not lead to a disconnect due
to an unhandled exception. Instead wrap those in an exception that is
handled by the parsing exception callback and ask the user to fill a
bug report for those faulty parsers.

We may adjust the list of exceptions that are wrapped in the future.

smack-core/src/main/java/org/jivesoftware/smack/AbstractXMPPConnection.java

@@ -1460,7 +1460,14 @@ protected void parseAndProcessStanza(XmlPullParser parser)
         int parserDepth = parser.getDepth();
         Stanza stanza = null;
         try {
-            stanza = PacketParserUtils.parseStanza(parser, incomingStreamXmlEnvironment);
+            try {
+                stanza = PacketParserUtils.parseStanza(parser, incomingStreamXmlEnvironment);
+            } catch (NullPointerException | NumberFormatException e) {
+                // Those exceptions should probably be wrapped into a SmackParsingException and therefore likely constitute a missing verification in the throwing parser.
+                String message = "Smack parser throw unexpected exception '" + e.getMessage() + "', please report this at " + Smack.BUG_REPORT_URL;
+                LOGGER.log(Level.SEVERE, message, e);
+                throw new IOException(message, e);
+            }
         }
         catch (XmlPullParserException | SmackParsingException | IOException | IllegalArgumentException e) {
             CharSequence content = PacketParserUtils.parseContentDepth(parser,

smack-core/src/main/java/org/jivesoftware/smack/Smack.java

@@ -1,6 +1,6 @@
 /**
  *
- * Copyright 2020-2021 Florian Schmaus
+ * Copyright 2020-2024 Florian Schmaus
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -17,6 +17,8 @@
 package org.jivesoftware.smack;
 
 import java.io.InputStream;
+import java.net.MalformedURLException;
+import java.net.URL;
 import java.util.logging.Logger;
 
 import org.jivesoftware.smack.util.FileUtils;
@@ -29,6 +31,16 @@ public class Smack {
 
     public static final String SMACK_PACKAGE = SMACK_ORG + ".smack";
 
+    public static final URL BUG_REPORT_URL;
+
+    static {
+        try {
+            BUG_REPORT_URL = new URL("https://discourse.igniterealtime.org/c/smack/smack-support/9");
+        } catch (MalformedURLException e) {
+            throw new ExceptionInInitializerError(e);
+        }
+    }
+
     /**
      * Returns the Smack version information, e.g."1.3.0".
      *