[Downloads] Always call DM::StartDownload() for explicit downloads.

chrome/browser/download/download_target_determiner.cc

 // Copyright 2013 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "chrome/browser/download/download_target_determiner.h"
 
 #include "base/prefs/pref_service.h"
 #include "base/rand_util.h"
 #include "base/strings/stringprintf.h"
 #include "base/time/time.h"
@@ skipping 189 matching lines @@
   } else {
     virtual_path_ = download_->GetForcedFilePath();
     // If this is a resumed download which was previously interrupted due to an
     // issue with the forced path, the user is still not prompted. If the path
     // supplied to a programmatic download is invalid, then the caller needs to
     // intervene.
   }
   DCHECK(virtual_path_.IsAbsolute());
   DVLOG(20) << "Generated virtual path: " << virtual_path_.AsUTF8Unsafe();
 
-  // If the download is DOA, don't bother going any further. This would be the
-  // case for a download that failed to initialize (e.g. the initial temporary
-  // file couldn't be created because both the downloads directory and the
-  // temporary directory are unwriteable).
-  //
-  // A virtual path is determined for DOA downloads for display purposes. This
-  // is why this check is performed here instead of at the start.
-  if (download_->GetState() != DownloadItem::IN_PROGRESS)
-    return COMPLETE;
   return CONTINUE;
 }
 
 DownloadTargetDeterminer::Result
     DownloadTargetDeterminer::DoNotifyExtensions() {
   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
   DCHECK(!virtual_path_.empty());
 
   next_state_ = STATE_RESERVE_VIRTUAL_PATH;
 
-  if (!should_notify_extensions_)
+  if (!should_notify_extensions_ ||
+      download_->GetState() != DownloadItem::IN_PROGRESS)
     return CONTINUE;
 
   delegate_->NotifyExtensions(download_, virtual_path_,
       base::Bind(&DownloadTargetDeterminer::NotifyExtensionsDone,
                  weak_ptr_factory_.GetWeakPtr()));
   return QUIT_DOLOOP;
 }
 
 void DownloadTargetDeterminer::NotifyExtensionsDone(
     const base::FilePath& suggested_path,
@@ skipping 22 matching lines @@
 
   DoLoop();
 }
 
 DownloadTargetDeterminer::Result
     DownloadTargetDeterminer::DoReserveVirtualPath() {
   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
   DCHECK(!virtual_path_.empty());
 
   next_state_ = STATE_PROMPT_USER_FOR_DOWNLOAD_PATH;
+  if (download_->GetState() != DownloadItem::IN_PROGRESS)
+    return CONTINUE;
 
   delegate_->ReserveVirtualPath(
       download_, virtual_path_, create_target_directory_, conflict_action_,
       base::Bind(&DownloadTargetDeterminer::ReserveVirtualPathDone,
                  weak_ptr_factory_.GetWeakPtr()));
   return QUIT_DOLOOP;
 }
 
 void DownloadTargetDeterminer::ReserveVirtualPathDone(
     const base::FilePath& path, bool verified) {
   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
   DVLOG(20) << "Reserved path: " << path.AsUTF8Unsafe()
             << " Verified:" << verified;
   should_prompt_ = (should_prompt_ || !verified);
   virtual_path_ = path;
   DoLoop();
 }
 
 DownloadTargetDeterminer::Result
     DownloadTargetDeterminer::DoPromptUserForDownloadPath() {
   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
   DCHECK(!virtual_path_.empty());
 
   next_state_ = STATE_DETERMINE_LOCAL_PATH;
 
-  if (should_prompt_) {
+  // Avoid prompting for a download if it isn't in-progress. The user will be
+  // prompted once the download is resumed and headers are available.
+  if (should_prompt_ && download_->GetState() == DownloadItem::IN_PROGRESS) {
     delegate_->PromptUserForDownloadPath(
         download_,
         virtual_path_,
         base::Bind(&DownloadTargetDeterminer::PromptUserForDownloadPathDone,
                    weak_ptr_factory_.GetWeakPtr()));
     return QUIT_DOLOOP;
   }
   return CONTINUE;
 }
 
@@ skipping 170 matching lines @@
   is_filetype_handled_safely_ = is_handled_safely;
   DVLOG(20) << "Is file type handled safely: " << is_filetype_handled_safely_;
   DoLoop();
 }
 
 DownloadTargetDeterminer::Result
     DownloadTargetDeterminer::DoCheckDownloadUrl() {
   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
   DCHECK(!virtual_path_.empty());
   next_state_ = STATE_CHECK_VISITED_REFERRER_BEFORE;
+
+  // Downloads that are already interrupted aren't checked for malicious URLs.
+  // Such downloads were unsuccessful at initiation and there should be no data
+  // saved at this point for the user to discard. If the download is
+  // subsequently resumed, DownloadTargetDeterminer would be invoked again and
+  // the URL check would be performed if the resumption was successful.
+  if (download_->GetState() != DownloadItem::IN_PROGRESS) {
+    DCHECK(download_->GetFullPath().empty());
+    return CONTINUE;
+  }
+
   delegate_->CheckDownloadUrl(
       download_,
       virtual_path_,
       base::Bind(&DownloadTargetDeterminer::CheckDownloadUrlDone,
                  weak_ptr_factory_.GetWeakPtr()));
   return QUIT_DOLOOP;
 }
 
 void DownloadTargetDeterminer::CheckDownloadUrlDone(
     content::DownloadDangerType danger_type) {
   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
   DVLOG(20) << "URL Check Result:" << danger_type;
   danger_type_ = danger_type;
   DoLoop();
 }
 
 DownloadTargetDeterminer::Result
     DownloadTargetDeterminer::DoCheckVisitedReferrerBefore() {
   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
 
   next_state_ = STATE_DETERMINE_INTERMEDIATE_PATH;
 
+  // If the download is already interrupted, there should be no download file
+  // on-disk. So skip the danger type determination since there's no file for
+  // the user to discard. Also the absence of a on-disk file prevents a filename
+  // based attack (e.g. creating a foo.exe.local file). If the download is
+  // successfully resumed, then DownloadTargetDeterminer would be invoked again
+  // at which point the danger level would be determined again.
+  if (download_->GetState() != DownloadItem::IN_PROGRESS)
+    return CONTINUE;
+
   // Checking if there are prior visits to the referrer is only necessary if the
   // danger level of the download depends on the file type. This excludes cases
   // where the download has already been deemed dangerous, or where the user is
   // going to be prompted or where this is a programmatic download.
   if (danger_type_ != content::DOWNLOAD_DANGER_TYPE_NOT_DANGEROUS)
     return CONTINUE;
 
   // Assume that:
   // IsDangerousFile(VISITED_REFERRER) => IsDangerousFile(NO_VISITS_...)
   // I.e. having visited a referrer only lowers a file's danger level.
@@ skipping 278 matching lines @@
   // asynchronously.
   new DownloadTargetDeterminer(download, initial_virtual_path, download_prefs,
                                delegate, callback);
 }
 
 // static
 base::FilePath DownloadTargetDeterminer::GetCrDownloadPath(
     const base::FilePath& suggested_path) {
   return base::FilePath(suggested_path.value() + kCrdownloadSuffix);
 }