Bug 1576333 - Part 1: Allow Downloads users to inspect HTTP codes r=mak

Differential Revision: https://phabricator.services.mozilla.com/D43342

--HG--
extra : moz-landing-system : lando

toolkit/components/downloads/DownloadCore.jsm

@@ -1329,6 +1329,23 @@ this.DownloadSource.prototype = {
    */
   adjustChannel: null,
 
+  /**
+   * For downloads handled by the (default) DownloadCopySaver, this function
+   * will determine, if provided, if a download can progress or has to be
+   * cancelled based on the HTTP status code of the network channel.
+   *
+   * @note If this is defined this object will not be serializable, thus the
+   *       Download object will not be persisted across sessions.
+   *
+   * @param aDownload
+   *        The download asking.
+   * @param aStatus
+   *        The HTTP status in question
+   *
+   * @return {Boolean} Download can progress
+   */
+  allowHttpStatus: null,
+
   /**
    * Returns a static representation of the current object state.
    *
@@ -1340,6 +1357,11 @@ this.DownloadSource.prototype = {
       return null;
     }
 
+    if (this.allowHttpStatus) {
+      // If the callback was used, we can't reproduce this across sessions.
+      return null;
+    }
+
     // Simplify the representation if we don't have other details.
     if (!this.isPrivate && !this.referrerInfo && !this._unknownProperties) {
       return this.url;
@@ -1381,6 +1403,11 @@ this.DownloadSource.prototype = {
  *                         this function can adjust the network channel before
  *                         it is opened, for example to change the HTTP headers
  *                         or to upload a stream as POST data.  Optional.
+ *          allowHttpStatus: For downloads handled by the (default)
+ *                           DownloadCopySaver, this function will determine, if
+ *                           provided, if a download can progress or has to be
+ *                           cancelled based on the HTTP status code of the
+ *                           network channel.
  *        }
  *
  * @return The newly created DownloadSource object.
@@ -1419,6 +1446,10 @@ this.DownloadSource.fromSerializable = function(aSerializable) {
       source.adjustChannel = aSerializable.adjustChannel;
     }
 
+    if ("allowHttpStatus" in aSerializable) {
+      source.allowHttpStatus = aSerializable.allowHttpStatus;
+    }
+
     deserializeUnknownProperties(
       source,
       aSerializable,
@@ -2103,6 +2134,19 @@ this.DownloadCopySaver.prototype = {
             return;
           }
 
+          // Check back with the initiator if we should allow a certain
+          // HTTP code. By default, we'll just save error pages too,
+          // however a consumer down the line, such as the WebExtensions
+          // downloads API might want to handle this differently.
+          if (
+            download.source.allowHttpStatus &&
+            aRequest instanceof Ci.nsIHttpChannel &&
+            !download.source.allowHttpStatus(download, aRequest.responseStatus)
+          ) {
+            aRequest.cancel(Cr.NS_BINDING_ABORTED);
+            return;
+          }
+
           aSetPropertiesFn({ contentType: channel.contentType });
 
           // Ensure we report the value of "Content-Length", if available,

toolkit/components/downloads/test/unit/head.js

@@ -916,6 +916,13 @@ add_task(function test_common_initialize() {
     }
   );
 
+  gHttpServer.registerPathHandler("/busy.txt", function(aRequest, aResponse) {
+    aResponse.setStatusLine("1.1", 504, "Gateway Timeout");
+    aResponse.setHeader("Content-Type", "text/plain", false);
+    aResponse.setHeader("Content-Length", "" + TEST_DATA_SHORT.length, false);
+    aResponse.write(TEST_DATA_SHORT);
+  });
+
   // This URL will emulate being blocked by Windows Parental controls
   gHttpServer.registerPathHandler("/parentalblocked.zip", function(
     aRequest,

toolkit/components/downloads/test/unit/test_DownloadCore.js

@@ -46,6 +46,80 @@ add_task(async function test_error_target_downloadingToSameFile() {
   );
 });
 
+/**
+ * Tests allowHttpStatus allowing requests
+ */
+add_task(async function test_error_notfound() {
+  const targetFile = getTempFile(TEST_TARGET_FILE_NAME);
+  let called = false;
+  const download = await Downloads.createDownload({
+    source: {
+      url: httpUrl("notfound.gone"),
+      allowHttpStatus(aDownload, aStatusCode) {
+        Assert.strictEqual(download, aDownload, "Check Download objects");
+        Assert.strictEqual(aStatusCode, 404, "The status should be correct");
+        called = true;
+        return true;
+      },
+    },
+    target: targetFile,
+  });
+  await download.start();
+  Assert.ok(called, "allowHttpStatus should have been called");
+});
+
+/**
+ * Tests allowHttpStatus rejecting requests
+ */
+add_task(async function test_error_notfound_reject() {
+  const targetFile = getTempFile(TEST_TARGET_FILE_NAME);
+  let called = false;
+  const download = await Downloads.createDownload({
+    source: {
+      url: httpUrl("notfound.gone"),
+      allowHttpStatus(aDownload, aStatusCode) {
+        Assert.strictEqual(download, aDownload, "Check Download objects");
+        Assert.strictEqual(aStatusCode, 404, "The status should be correct");
+        called = true;
+        return false;
+      },
+    },
+    target: targetFile,
+  });
+  await Assert.rejects(
+    download.start(),
+    ex => ex instanceof Downloads.Error && ex.becauseSourceFailed,
+    "Download should have been rejected"
+  );
+  Assert.ok(called, "allowHttpStatus should have been called");
+});
+
+/**
+ * Tests allowHttpStatus rejecting requests other than 404
+ */
+add_task(async function test_error_busy_reject() {
+  const targetFile = getTempFile(TEST_TARGET_FILE_NAME);
+  let called = false;
+  const download = await Downloads.createDownload({
+    source: {
+      url: httpUrl("busy.txt"),
+      allowHttpStatus(aDownload, aStatusCode) {
+        Assert.strictEqual(download, aDownload, "Check Download objects");
+        Assert.strictEqual(aStatusCode, 504, "The status should be correct");
+        called = true;
+        return false;
+      },
+    },
+    target: targetFile,
+  });
+  await Assert.rejects(
+    download.start(),
+    ex => ex instanceof Downloads.Error && ex.becauseSourceFailed,
+    "Download should have been rejected"
+  );
+  Assert.ok(called, "allowHttpStatus should have been called");
+});
+
 /**
  * Tests the DownloadError object.
  */