[api-minor] Add support for a couple of white-listed `JavaScript` actions that contains valid URLs (issue 3897, bug 843699)

By only allowing very specific type of `JavaScript` actions, and also utilizing the existing `URL` validation, this patch shouldn't pose too much risk.

Fixes one of the points in issue 3897 (with the PDF file taken from issue 3438).
Fixes https://bugzilla.mozilla.org/show_bug.cgi?id=843699 (probably, since that bug doesn't contain a test-case).

src/core/obj.js

@@ -695,6 +695,33 @@ var Catalog = (function CatalogClosure() {
           }
           break;
 
+        case 'JavaScript':
+          var jsAction = action.get('JS'), js;
+          if (isStream(jsAction)) {
+            js = bytesToString(jsAction.getBytes());
+          } else if (isString(jsAction)) {
+            js = jsAction;
+          }
+
+          if (js) {
+            // Attempt to recover valid URLs from 'JS' entries with certain
+            // white-listed formats, e.g.
+            //  - window.open('http://example.com')
+            //  - app.launchURL('http://example.com', true)
+            var URL_OPEN_METHODS = [
+              'app.launchURL',
+              'window.open'
+            ];
+            var regex = new RegExp('^(?:' + URL_OPEN_METHODS.join('|') + ')' +
+                                   '\\((?:\'|\")(\\S+)(?:\'|\")(?:,|\\))');
+
+            var jsUrl = regex.exec(stringToPDFString(js), 'i');
+            if (jsUrl && jsUrl[1]) {
+              url = jsUrl[1];
+              break;
+            }
+          }
+          /* falls through */
         default:
           warn('Catalog_parseDestDictionary: Unrecognized link type "' +
                linkType + '".');

test/unit/annotation_layer_spec.js

@@ -544,6 +544,60 @@ describe('Annotation layer', function() {
       expect(data.newWindow).toEqual(true);
     });
 
+    it('should recover valid URLs from JavaScript actions having certain ' +
+       'white-listed formats', function () {
+      function checkJsAction(params) {
+        var jsEntry = params.jsEntry;
+        var expectedUrl = params.expectedUrl;
+        var expectedUnsafeUrl = params.expectedUnsafeUrl;
+
+        var actionDict = new Dict();
+        actionDict.set('Type', Name.get('Action'));
+        actionDict.set('S', Name.get('JavaScript'));
+        actionDict.set('JS', jsEntry);
+
+        var annotationDict = new Dict();
+        annotationDict.set('Type', Name.get('Annot'));
+        annotationDict.set('Subtype', Name.get('Link'));
+        annotationDict.set('A', actionDict);
+
+        var annotationRef = new Ref(46, 0);
+        var xref = new XRefMock([
+          { ref: annotationRef, data: annotationDict, }
+        ]);
+
+        var annotation = annotationFactory.create(xref, annotationRef,
+                                                  pdfManagerMock);
+        var data = annotation.data;
+        expect(data.annotationType).toEqual(AnnotationType.LINK);
+
+        expect(data.url).toEqual(expectedUrl);
+        expect(data.unsafeUrl).toEqual(expectedUnsafeUrl);
+        expect(data.dest).toBeUndefined();
+        expect(data.newWindow).toBeFalsy();
+      }
+
+      // Check that we reject a 'JS' entry containing arbitrary JavaScript.
+      checkJsAction({
+        jsEntry: 'function someFun() { return "qwerty"; } someFun();',
+        expectedUrl: undefined,
+        expectedUnsafeUrl: undefined,
+      });
+      // Check that we accept a white-listed {string} 'JS' entry.
+      checkJsAction({
+        jsEntry: 'window.open(\'http://www.example.com/test.pdf\')',
+        expectedUrl: new URL('http://www.example.com/test.pdf').href,
+        expectedUnsafeUrl: 'http://www.example.com/test.pdf',
+      });
+      // Check that we accept a white-listed {Stream} 'JS' entry.
+      checkJsAction({
+        jsEntry: new StringStream(
+                   'app.launchURL("http://www.example.com/test.pdf", true)'),
+        expectedUrl: new URL('http://www.example.com/test.pdf').href,
+        expectedUnsafeUrl: 'http://www.example.com/test.pdf',
+      });
+    });
+
     it('should correctly parse a Named action', function() {
       var actionDict = new Dict();
       actionDict.set('Type', Name.get('Action'));