Implement replaceUrl protocol for safe URL replacements

src/service/viewer-impl.js

@@ -22,6 +22,7 @@ import {registerServiceBuilderForDoc} from '../service';
 import {dev, duplicateErrorIfNecessary} from '../log';
 import {isIframed} from '../dom';
 import {
+  getSourceOrigin,
   parseQueryString,
   parseUrl,
   removeFragment,
@@ -362,6 +363,27 @@ export class Viewer {
       }
     });
 
+    // Replace URL if requested.
+    const replaceUrlParam = this.params_['replaceUrl'];
+    if (ampdoc.isSingleDoc() &&
+        replaceUrlParam &&
+        this.win.history.replaceState) {
+      try {
+        // The origin and source origin must match.
+        const url = parseUrl(this.win.location.href);
+        const replaceUrl = parseUrl(
+            removeFragment(replaceUrlParam) + this.win.location.hash);
+        if (url.origin == replaceUrl.origin &&
+            getSourceOrigin(url) == getSourceOrigin(replaceUrl)) {
+          this.win.history.replaceState({}, '', replaceUrl.href);
+          this.win.location.originalHref = url.href;
+          dev().fine(TAG_, 'replace url:' + replaceUrl.href);
+        }
+      } catch (e) {
+        dev().error(TAG_, 'replaceUrl failed', e);
+      }
+    }
+
     // Remove hash when we have an incoming click tracking string
     // (see impression.js).
     if (this.params_['click']) {
@@ -373,7 +395,7 @@ export class Viewer {
           this.win.location.originalHash = this.win.location.hash;
         }
         this.win.history.replaceState({}, '', newUrl);
-        dev().fine(TAG_, 'replace url:' + this.win.location.href);
+        dev().fine(TAG_, 'replace fragment:' + this.win.location.href);
       }
     }
 
@@ -941,6 +963,7 @@ function getChannelError(opt_reason) {
   return new Error('No messaging channel: ' + opt_reason);
 }
 
+
 /**
  * Sets the viewer visibility state. This calls is restricted to runtime only.
  * @param {!VisibilityState} state

test/functional/test-viewer.js

@@ -20,6 +20,7 @@ import {dev} from '../../src/log';
 import {installDocService} from '../../src/service/ampdoc-impl';
 import {installPlatformService} from '../../src/service/platform-impl';
 import {installTimerService} from '../../src/service/timer-impl';
+import {parseUrl, removeFragment} from '../../src/url';
 import * as sinon from 'sinon';
 
 
@@ -76,8 +77,11 @@ describe('Viewer', () => {
     };
     windowApi.navigator = window.navigator;
     windowApi.history = {
-      replaceState: sandbox.spy(),
+      replaceState: () => {},
     };
+    sandbox.stub(windowApi.history, 'replaceState', (state, title, url) => {
+      windowApi.location.href = url;
+    });
     installDocService(windowApi, /* isSingleDoc */ true);
     ampdoc = ampdocServiceFor(windowApi).getAmpDoc();
     installPlatformService(windowApi);
@@ -226,6 +230,100 @@ describe('Viewer', () => {
     expect(viewportEvent).to.not.equal(null);
   });
 
+  describe('replaceUrl', () => {
+    function setUrl(href) {
+      const url = parseUrl(href);
+      windowApi.location.href = url.href;
+      windowApi.location.hash = url.hash;
+    }
+
+    it('should replace URL for the same non-proxy origin', () => {
+      const fragment = '#replaceUrl=http://www.example.com/two%3Fa%3D1&b=1';
+      setUrl('http://www.example.com/one' + fragment);
+      new Viewer(ampdoc);
+      expect(windowApi.history.replaceState).to.be.calledOnce;
+      expect(windowApi.history.replaceState).to.be.calledWith({}, '',
+          'http://www.example.com/two?a=1' + fragment);
+      expect(ampdoc.getUrl())
+          .to.equal('http://www.example.com/two?a=1' + fragment);
+      expect(windowApi.location.originalHref)
+          .to.equal('http://www.example.com/one' + fragment);
+    });
+
+    it('should ignore replacement fragment', () => {
+      const fragment = '#replaceUrl=http://www.example.com/two%23b=2&b=1';
+      setUrl('http://www.example.com/one' + fragment);
+      new Viewer(ampdoc);
+      expect(windowApi.history.replaceState).to.be.calledOnce;
+      expect(windowApi.history.replaceState).to.be.calledWith({}, '',
+          'http://www.example.com/two' + fragment);
+      expect(windowApi.location.originalHref)
+          .to.equal('http://www.example.com/one' + fragment);
+    });
+
+    it('should replace relative URL for the same non-proxy origin', () => {
+      const fragment = '#replaceUrl=/two&b=1';
+      setUrl(removeFragment(window.location.href) + fragment);
+      new Viewer(ampdoc);
+      expect(windowApi.history.replaceState).to.be.calledOnce;
+      expect(windowApi.history.replaceState).to.be.calledWith({}, '',
+          window.location.origin + '/two' + fragment);
+      expect(windowApi.location.originalHref)
+          .to.equal(removeFragment(window.location.href) + fragment);
+    });
+
+    it('should fail to replace URL for a wrong non-proxy origin', () => {
+      const fragment = '#replaceUrl=http://other.example.com/two&b=1';
+      setUrl('http://www.example.com/one' + fragment);
+      new Viewer(ampdoc);
+      expect(windowApi.history.replaceState).to.not.be.called;
+      expect(windowApi.location.originalHref).to.be.undefined;
+    });
+
+    it('should tolerate errors when trying to replace URL', () => {
+      const fragment = '#replaceUrl=http://www.example.com/two&b=1';
+      setUrl('http://www.example.com/one' + fragment);
+      windowApi.history.replaceState.restore();
+      sandbox.stub(windowApi.history, 'replaceState', () => {
+        throw new Error('intentional');
+      });
+      expect(() => {
+        new Viewer(ampdoc);
+      }).to.not.throw();
+      expect(windowApi.location.originalHref).to.be.undefined;
+    });
+
+    it('should replace URL for the same source origin on proxy', () => {
+      const fragment =
+          '#replaceUrl=https://cdn.ampproject.org/c/www.example.com/two&b=1';
+      setUrl('https://cdn.ampproject.org/c/www.example.com/one' + fragment);
+      new Viewer(ampdoc);
+      expect(windowApi.history.replaceState).to.be.calledOnce;
+      expect(windowApi.history.replaceState).to.be.calledWith({}, '',
+          'https://cdn.ampproject.org/c/www.example.com/two' + fragment);
+      expect(windowApi.location.originalHref)
+          .to.equal('https://cdn.ampproject.org/c/www.example.com/one' +
+              fragment);
+    });
+
+    it('should fail replace URL for wrong source origin on proxy', () => {
+      const fragment =
+          '#replaceUrl=https://cdn.ampproject.org/c/other.example.com/two&b=1';
+      setUrl('https://cdn.ampproject.org/c/www.example.com/one' + fragment);
+      new Viewer(ampdoc);
+      expect(windowApi.history.replaceState).to.not.be.called;
+      expect(windowApi.location.originalHref).to.be.undefined;
+    });
+
+    it('should NOT replace URL in shadow doc', () => {
+      const fragment = '#replaceUrl=http://www.example.com/two&b=1';
+      setUrl('http://www.example.com/one' + fragment);
+      sandbox.stub(ampdoc, 'isSingleDoc', () => false);
+      new Viewer(ampdoc);
+      expect(windowApi.history.replaceState).to.not.be.called;
+    });
+  });
+
   describe('should receive the visibilitychange event', () => {
     it('should change prerenderSize', () => {
       viewer.receiveMessage('visibilitychange', {