fix($http): only parse as JSON when opening/closing brackets match

Previously, due to weak JSON-detecting RegExp, string like `[...}` and
`{...]` would be considered JSON (even if they obviously aren't) and an
expection would be thrown while trying to parse them.

This commit makes sure the opening and closing brackets match. This
doesn't completely eliminate false positives (e.g. `[]{}[]`), but does
help reduce them.

Closes angular#10349

Author: gkalpak

src/ng/http.js

@@ -2,23 +2,35 @@
 
 var APPLICATION_JSON = 'application/json';
 var CONTENT_TYPE_APPLICATION_JSON = {'Content-Type': APPLICATION_JSON + ';charset=utf-8'};
-var JSON_START = /^\s*(\[|\{[^\{])/;
-var JSON_END = /[\}\]]\s*$/;
+var JSON_START = /^\[|^\{(?!\{)/;
+var JSON_ENDS = {
+  '[': /]$/,
+  '{': /}$/
+};
 var JSON_PROTECTION_PREFIX = /^\)\]\}',?\n/;
 
 function defaultHttpResponseTransform(data, headers) {
   if (isString(data)) {
-    // strip json vulnerability protection prefix
-    data = data.replace(JSON_PROTECTION_PREFIX, '');
-    var contentType = headers('Content-Type');
-    if ((contentType && contentType.indexOf(APPLICATION_JSON) === 0 && data.trim()) ||
-        (JSON_START.test(data) && JSON_END.test(data))) {
-      data = fromJson(data);
+    // Strip json vulnerability protection prefix and trim whitespace
+    var tempData = data.replace(JSON_PROTECTION_PREFIX, '').trim();
+
+    if (tempData) {
+      var contentType = headers('Content-Type');
+      if ((contentType && (contentType.indexOf(APPLICATION_JSON) === 0)) || isJsonLike(tempData)) {
+        // Parse JSON
+        data = fromJson(tempData);
+      }
     }
   }
+
   return data;
 }
 
+function isJsonLike(str) {
+    var jsonStart = str.match(JSON_START);
+    return jsonStart && JSON_ENDS[jsonStart[0]].test(str);
+}
+
 /**
  * Parse headers into key value object
  *

test/ng/httpSpec.js

@@ -1055,6 +1055,16 @@ describe('$http', function() {
           });
 
 
+          it('should ignore leading/trailing whitespace', function() {
+            $httpBackend.expect('GET', '/url').respond('  \n  {"foo":"bar","baz":23}  \r\n  \n  ');
+            $http({method: 'GET', url: '/url'}).success(callback);
+            $httpBackend.flush();
+
+            expect(callback).toHaveBeenCalledOnce();
+            expect(callback.mostRecentCall.args[0]).toEqual({foo: 'bar', baz: 23});
+          });
+
+
           it('should deserialize json numbers when response header contains application/json',
               function() {
             $httpBackend.expect('GET', '/url').respond('123', {'Content-Type': 'application/json'});
@@ -1141,6 +1151,16 @@ describe('$http', function() {
           });
 
 
+          it('should retain security prefix if response is not json', function() {
+            $httpBackend.expect('GET', '/url').respond(')]}\',\n This is not JSON !');
+            $http({method: 'GET', url: '/url'}).success(callback);
+            $httpBackend.flush();
+
+            expect(callback).toHaveBeenCalledOnce();
+            expect(callback.mostRecentCall.args[0]).toEqual(')]}\',\n This is not JSON !');
+          });
+
+
           it('should not attempt to deserialize json when HEAD request', function() {
             //per http spec for Content-Type, HEAD request should return a Content-Type header
             //set to what the content type would have been if a get was sent
@@ -1182,6 +1202,20 @@ describe('$http', function() {
             expect(callback).toHaveBeenCalledOnce();
             expect(callback.mostRecentCall.args[0]).toEqual('{{some}}');
           });
+
+          it('should not deserialize json when the opening and closing brackets do not match',
+            function() {
+              $httpBackend.expect('GET', '/url1').respond('[Code](url): function() {}');
+              $httpBackend.expect('GET', '/url2').respond('{"is": "not"} ["json"]');
+              $http.get('/url1').success(callback);
+              $http.get('/url2').success(callback);
+              $httpBackend.flush();
+
+              expect(callback.calls.length).toBe(2);
+              expect(callback.calls[0].args[0]).toEqual('[Code](url): function() {}');
+              expect(callback.calls[1].args[0]).toEqual('{"is": "not"} ["json"]');
+            }
+          );
         });