Use better fallback URLs when calling AVScanFile().

content/browser/download/base_file.cc

 // Copyright (c) 2012 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 "content/browser/download/base_file.h"
 
 #include <utility>
 
 #include "base/bind.h"
 #include "base/files/file.h"
@@ skipping 356 matching lines @@
   DVLOG(1) << __func__ << "() operation:" << operation
            << " os_error:" << os_error
            << " reason:" << DownloadInterruptReasonToString(reason);
   net_log_.AddEvent(
       net::NetLogEventType::DOWNLOAD_FILE_ERROR,
       base::Bind(&FileInterruptedNetLogCallback, operation, os_error, reason));
   return reason;
 }
 
 #if defined(OS_WIN) || defined(OS_MACOSX) || defined(OS_LINUX)
+
+namespace {
+
+// Given a source and a referrer, determines the "safest" URL that can be used
+// to determine the authority of the download source. Returns an empty URL if no
+// HTTP/S URL can be determined for the <|source_url|, |referrer_url|> pair.
+GURL GetEffectiveAuthorityURL(const GURL& source_url,
+                              const GURL& referrer_url) {
+  if (source_url.is_valid()) {
+    // http{,s} has an authority and are supported.
+    if (source_url.SchemeIsHTTPOrHTTPS())
+      return source_url;
+
+    // If the download source is file:// ideally we should copy the MOTW from
+    // the original file, but given that Chrome/Chromium places strict
+    // restrictions on which schemes can reference file:// URLs, this code is
+    // going to assume that at this point it's okay to treat this download as
+    // being from the local system.
+    if (source_url.SchemeIsFile())
+      return source_url;
+
+    // ftp:// has an authority.
+    if (source_url.SchemeIs(url::kFtpScheme))
+      return source_url;
+  }
+
+  if (referrer_url.is_valid() && referrer_url.SchemeIsHTTPOrHTTPS())
+    return referrer_url;
+
+  return GURL();
+}
+
+}  // namespace
+
 DownloadInterruptReason BaseFile::AnnotateWithSourceInformation(
     const std::string& client_guid,
     const GURL& source_url,
     const GURL& referrer_url) {
   DCHECK_CURRENTLY_ON(BrowserThread::FILE);
   DCHECK(!detached_);
   DCHECK(!full_path_.empty());
 
   net_log_.BeginEvent(net::NetLogEventType::DOWNLOAD_FILE_ANNOTATED);
-  QuarantineFileResult result =
-      QuarantineFile(full_path_, source_url, referrer_url, client_guid);
+  QuarantineFileResult result = QuarantineFile(
+      full_path_, GetEffectiveAuthorityURL(source_url, referrer_url),
+      referrer_url, client_guid);
   net_log_.EndEvent(net::NetLogEventType::DOWNLOAD_FILE_ANNOTATED);
   switch (result) {
     case QuarantineFileResult::OK:
       return DOWNLOAD_INTERRUPT_REASON_NONE;
     case QuarantineFileResult::VIRUS_INFECTED:
       return DOWNLOAD_INTERRUPT_REASON_FILE_VIRUS_INFECTED;
     case QuarantineFileResult::SECURITY_CHECK_FAILED:
       return DOWNLOAD_INTERRUPT_REASON_FILE_SECURITY_CHECK_FAILED;
     case QuarantineFileResult::BLOCKED_BY_POLICY:
       return DOWNLOAD_INTERRUPT_REASON_FILE_BLOCKED;
@@ skipping 26 matching lines @@
 #else  // !OS_WIN && !OS_MACOSX && !OS_LINUX
 DownloadInterruptReason BaseFile::AnnotateWithSourceInformation(
     const std::string& client_guid,
     const GURL& source_url,
     const GURL& referrer_url) {
   return DOWNLOAD_INTERRUPT_REASON_NONE;
 }
 #endif
 
 }  // namespace content