Match Pepper UMA histograms by prefix

chrome/renderer/pepper/pepper_uma_host.cc

 // Copyright 2014 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/renderer/pepper/pepper_uma_host.h"
 
 #include "base/metrics/histogram.h"
 #include "base/sha1.h"
 #include "base/strings/string_number_conversions.h"
 #include "chrome/common/chrome_switches.h"
 #include "chrome/renderer/chrome_content_renderer_client.h"
 #include "content/public/renderer/renderer_ppapi_host.h"
 #include "extensions/common/constants.h"
 #include "extensions/common/extension.h"
 #include "ppapi/c/pp_errors.h"
 #include "ppapi/host/dispatch_host_message.h"
 #include "ppapi/host/host_message_context.h"
 #include "ppapi/host/ppapi_host.h"
 #include "ppapi/proxy/ppapi_messages.h"
 
 namespace {
 
 const char* kPredefinedAllowedUMAOrigins[] = {
   "6EAED1924DB611B6EEF2A664BD077BE7EAD33B8F",  // see crbug.com/317833
   "4EB74897CB187C7633357C2FE832E0AD6A44883A"   // see crbug.com/317833
 };
 
-const char* kWhitelistedHistogramHashes[] = {
-  "F131550DAB7A7C6E6633EF81FB5998CC0482AC63",  // see crbug.com/317833
-  "13955AB4DAD798384DFB4304734FCF2A95F353CC",  // see crbug.com/317833
-  "404E800582901F1B937B8E287235FC603A5DEDFB"   // see crbug.com/317833
+// The first 12 characters must match one of the prefixes below.
+const int kWhitelistedHistogramPrefixLength = 12;

[Ilya Sherman, 2014/03/06 00:34:14]

Hmm, maybe scan up to the first dot instead?

[elijahtaylor1, 2014/03/06 00:46:27]

Great suggestion.  Done.

+
+const char* kWhitelistedHistogramPrefixes[] = {

[Ilya Sherman, 2014/03/06 00:34:14]

nit: "const char* const"

[elijahtaylor1, 2014/03/06 00:46:27]

Done.

+  "CD190EA2B764EDF0BB97552A638D32072F3CFD41",  // see crbug.com/317833

[Ilya Sherman, 2014/03/06 00:34:14]

nit: Links should start with "http://".  Also, this is a restricted bug, which
might frustrate some folks trying to understand the code... but maybe that's the
best we can do in this case?

[elijahtaylor1, 2014/03/06 00:46:27]

Fixed "http://"

Yeah, I agree that could be frustrating, but the alternative right now is no bug
link to explain it, which would frustrate all folks.

 };
 
-std::string HashHistogram(const std::string& histogram) {
-  const std::string id_hash = base::SHA1HashString(histogram);
+
+std::string HashPrefix(const std::string& histogram) {
+  const std::string id_hash = base::SHA1HashString(
+      histogram.substr(0, kWhitelistedHistogramPrefixLength));
   DCHECK_EQ(id_hash.length(), base::kSHA1Length);
   return base::HexEncode(id_hash.c_str(), id_hash.length());
 }
 
 }  // namespace
 
 PepperUMAHost::PepperUMAHost(
     content::RendererPpapiHost* host,
     PP_Instance instance,
     PP_Resource resource)
     : ResourceHost(host->GetPpapiHost(), instance, resource),
       document_url_(host->GetDocumentURL(instance)),
       is_plugin_in_process_(host->IsRunningInProcess()) {
   for (size_t i = 0; i < arraysize(kPredefinedAllowedUMAOrigins); ++i)
     allowed_origins_.insert(kPredefinedAllowedUMAOrigins[i]);
-  for (size_t i = 0; i < arraysize(kWhitelistedHistogramHashes); ++i)
-    allowed_histograms_.insert(kWhitelistedHistogramHashes[i]);
+  for (size_t i = 0; i < arraysize(kWhitelistedHistogramPrefixes); ++i)
+    allowed_histogram_prefixes_.insert(kWhitelistedHistogramPrefixes[i]);
 }
 
 PepperUMAHost::~PepperUMAHost() {
 }
 
 int32_t PepperUMAHost::OnResourceMessageReceived(
     const IPC::Message& msg,
     ppapi::host::HostMessageContext* context) {
   IPC_BEGIN_MESSAGE_MAP(PepperUMAHost, msg)
     PPAPI_DISPATCH_HOST_RESOURCE_CALL(PpapiHostMsg_UMA_HistogramCustomTimes,
         OnHistogramCustomTimes);
     PPAPI_DISPATCH_HOST_RESOURCE_CALL(PpapiHostMsg_UMA_HistogramCustomCounts,
         OnHistogramCustomCounts);
     PPAPI_DISPATCH_HOST_RESOURCE_CALL(PpapiHostMsg_UMA_HistogramEnumeration,
         OnHistogramEnumeration);
   IPC_END_MESSAGE_MAP()
   return PP_ERROR_FAILED;
 }
 
 bool PepperUMAHost::IsHistogramAllowed(const std::string& histogram) {
   if (is_plugin_in_process_ && histogram.find("NaCl.") == 0) {
     return true;
   }
 
   bool is_whitelisted =
       ChromeContentRendererClient::IsExtensionOrSharedModuleWhitelisted(
           document_url_, allowed_origins_);
   if (is_whitelisted &&
-      allowed_histograms_.find(HashHistogram(histogram)) !=
-          allowed_histograms_.end()) {
+      allowed_histogram_prefixes_.find(HashPrefix(histogram)) !=
+          allowed_histogram_prefixes_.end()) {
     return true;
   }
 
   LOG(ERROR) << "Host or histogram name is not allowed to use the UMA API.";
   return false;
 }
 
 #define RETURN_IF_BAD_ARGS(_min, _max, _buckets) \
   do { \
     if (_min >= _max || _buckets <= 1) \
@@ skipping 60 matching lines @@
       base::LinearHistogram::FactoryGet(
           name,
           1,
           boundary_value,
           boundary_value + 1,
           base::HistogramBase::kUmaTargetedHistogramFlag);
   counter->Add(sample);
   return PP_OK;
 }