Sniff 204 responses as text/plain to avoid creating unwanted downloads.

BUG=24391
TEST=ResourceDispatcherHostTest.MimeSniff204

Review URL: http://codereview.chromium.org/274075

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@29355 0039d316-1c4b-4281-b951-d872f2087c98

2 files changed, 34 insertions, 8 deletions

diff --git a/chrome/browser/renderer_host/buffered_resource_handler.cc b/chrome/browser/renderer_host/buffered_resource_handler.cc
index ad31e8d..347bf69 100644
--- a/chrome/browser/renderer_host/buffered_resource_handler.cc
+++ b/chrome/browser/renderer_host/buffered_resource_handler.cc
@@ -154,12 +154,11 @@ bool BufferedResourceHandler::DelayResponse() {
 
   const bool sniffing_blocked =
       LowerCaseEqualsASCII(content_type_options, "nosniff");
-  const bool no_data =
-      response_->response_head.headers &&  // Can be NULL if FTP.
-      (response_->response_head.headers->response_code() == 304 ||
-       response_->response_head.headers->response_code() == 204);
-  const bool we_would_like_to_sniff =
-      no_data ? false : net::ShouldSniffMimeType(request_->url(), mime_type);
+  const bool not_modified_status =
+      response_->response_head.headers &&
+      response_->response_head.headers->response_code() == 304;
+  const bool we_would_like_to_sniff = not_modified_status ?
+      false : net::ShouldSniffMimeType(request_->url(), mime_type);
 
   RecordSnifferMetrics(sniffing_blocked, we_would_like_to_sniff, mime_type);
 
@@ -172,7 +171,7 @@ bool BufferedResourceHandler::DelayResponse() {
     return true;
   }
 
-  if (sniffing_blocked && mime_type.empty() && !no_data) {
+  if (sniffing_blocked && mime_type.empty() && !not_modified_status) {
     // Ugg.  The server told us not to sniff the content but didn't give us a
     // mime type.  What's a browser to do?  Turns out, we're supposed to treat
     // the response as "text/plain".  This is the most secure option.
@@ -202,7 +201,7 @@ bool BufferedResourceHandler::DelayResponse() {
     return true;
   }
 
-  if (!no_data && ShouldWaitForPlugins()) {
+  if (!not_modified_status && ShouldWaitForPlugins()) {
     wait_for_plugins_ = true;
     return true;
   }
diff --git a/chrome/browser/renderer_host/resource_dispatcher_host_unittest.cc b/chrome/browser/renderer_host/resource_dispatcher_host_unittest.cc
index 78994a7..6c08025 100644
--- a/chrome/browser/renderer_host/resource_dispatcher_host_unittest.cc
+++ b/chrome/browser/renderer_host/resource_dispatcher_host_unittest.cc
@@ -846,3 +846,30 @@ TEST_F(ResourceDispatcherHostTest, MimeNotSniffed2) {
   GetResponseHead(msgs[0], &response_head);
   ASSERT_EQ("", response_head.mime_type);
 }
+
+TEST_F(ResourceDispatcherHostTest, MimeSniff204) {
+  EXPECT_EQ(0, host_.GetOutstandingRequestsMemoryCost(0));
+
+  std::string response("HTTP/1.1 204 No Content\n\n");
+  std::string raw_headers(net::HttpUtil::AssembleRawHeaders(response.data(),
+                                                            response.size()));
+  std::string response_data;
+  SetResponse(raw_headers, response_data);
+
+  HandleScheme("http");
+  MakeTestRequest(0, 1, GURL("http:bla"));
+
+  // Flush all pending requests.
+  while (URLRequestTestJob::ProcessOnePendingMessage());
+
+  EXPECT_EQ(0, host_.GetOutstandingRequestsMemoryCost(0));
+
+  // Sorts out all the messages we saw by request.
+  ResourceIPCAccumulator::ClassifiedMessages msgs;
+  accum_.GetClassifiedMessages(&msgs);
+  ASSERT_EQ(1U, msgs.size());
+
+  ResourceResponseHead response_head;
+  GetResponseHead(msgs[0], &response_head);
+  ASSERT_EQ("text/plain", response_head.mime_type);
+}