add some robustness

Author: vladak

opengrok-indexer/src/main/java/org/opengrok/indexer/configuration/Configuration.java

@@ -59,6 +59,7 @@
 import org.opengrok.indexer.authorization.AuthorizationStack;
 import org.opengrok.indexer.history.RepositoryInfo;
 import org.opengrok.indexer.logger.LoggerFactory;
+import org.opengrok.indexer.web.Util;
 
 import static org.opengrok.indexer.configuration.PatternUtil.compilePattern;
 
@@ -1642,5 +1643,12 @@ public void checkConfiguration() throws ConfigurationException {
             LOGGER.log(Level.INFO, "History based reindex is on, however history cache is off. " +
                     "History cache has to be enabled for history based reindex.");
         }
+
+        if (!Objects.isNull(getBugPage()) && !Util.isHttpUri(getBugPage())) {
+            throw new ConfigurationException("Bug page must be valid HTTP(S) URI");
+        }
+        if (!Objects.isNull(getReviewPage()) && !Util.isHttpUri(getReviewPage())) {
+            throw new ConfigurationException("Review page must be valid HTTP(S) URI");
+        }
     }
 }

opengrok-indexer/src/main/java/org/opengrok/indexer/web/Util.java

@@ -1603,6 +1603,9 @@ public static String buildLink(String name, String url, boolean newTab)
      * @return replacement for the first group in the pattern
      */
     private static String buildLinkReplacer(MatchResult result, String text, String url) {
+        if (result.groupCount() < 1) {
+            return result.group(0);
+        }
         final String group1 = result.group(1);
         final String appendedUrl = url + uriEncode(group1);
         try {

opengrok-indexer/src/test/java/org/opengrok/indexer/web/UtilTest.java

@@ -494,6 +494,14 @@ void testLinkifyPatternEscape() {
                 Util.linkifyPattern(text, Pattern.compile("[ \\t]+([0-9<>]{3,})[ \\t]*"), "http://www.example.com?bug="));
     }
 
+    @Test
+    void testLinkifyPatternNoGroup() {
+        final String text = "foo bug <123456> bar bug 777";
+
+        assertEquals(text,
+                Util.linkifyPattern(text, Pattern.compile("[0-9]{3,}"), "http://www.example.com?bug="));
+    }
+
     @Test
     void testCompleteUrl() {
         HttpServletRequest req = new DummyHttpServletRequest() {