Collect UMA data for Origin Trials

content/common/origin_trials/trial_token.cc

 // Copyright 2015 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/common/origin_trials/trial_token.h"
 
 #include <openssl/curve25519.h>
 
 #include <vector>
 
@@ skipping 25 matching lines @@
 
 // Version 2 is the only token version currently supported. Version 1 was
 // introduced in Chrome M50, and removed in M51. There were no experiments
 // enabled in the stable M50 release which would have used those tokens.
 const uint8_t kVersion2 = 2;
 
 }  // namespace
 
 TrialToken::~TrialToken() {}
 
-// static
+// Static

[Marijn Kruisselbrink, 2016/04/22 21:51:06]

the lowercase version of this comment is vastly more common than the uppercase
version, so not sure why you changed it (separately, the Extract and Parse
method should probably have a // static comment as well to be consistent).

[chasej, 2016/04/25 20:32:52]

Done.

 std::unique_ptr<TrialToken> TrialToken::From(const std::string& token_text,
-                                             base::StringPiece public_key) {
-  std::unique_ptr<std::string> token_payload = Extract(token_text, public_key);
-  if (!token_payload) {
+                                             base::StringPiece public_key,
+                                             TrialTokenStatus* out_status) {
+  DCHECK(out_status);
+  std::string token_payload;
+  *out_status = Extract(token_text, public_key, &token_payload);
+  if (*out_status != TRIAL_TOKEN_STATUS_SUCCESS) {
     return nullptr;
   }
-  return Parse(*token_payload);
+  std::unique_ptr<TrialToken> token = Parse(token_payload);
+  *out_status =
+      token ? TRIAL_TOKEN_STATUS_SUCCESS : TRIAL_TOKEN_STATUS_MALFORMED;
+  return token;
 }
 
-bool TrialToken::IsValidForFeature(const url::Origin& origin,
-                                   base::StringPiece feature_name,
-                                   const base::Time& now) const {
-  return ValidateOrigin(origin) && ValidateFeatureName(feature_name) &&
-         ValidateDate(now);
+TrialTokenStatus TrialToken::IsValidForFeature(const url::Origin& origin,
+                                               base::StringPiece feature_name,
+                                               const base::Time& now) const {
+  // The order of these checks is intentional. For example, will only report a
+  // token as expired if it is valid for the origin + feature combination.
+  if (!ValidateOrigin(origin)) {
+    return TRIAL_TOKEN_STATUS_WRONG_ORIGIN;
+  }
+  if (!ValidateFeatureName(feature_name)) {
+    return TRIAL_TOKEN_STATUS_WRONG_FEATURE;
+  }
+  if (!ValidateDate(now)) {
+    return TRIAL_TOKEN_STATUS_EXPIRED;
+  }
+  return TRIAL_TOKEN_STATUS_SUCCESS;
 }
 
-std::unique_ptr<std::string> TrialToken::Extract(
-    const std::string& token_payload,
-    base::StringPiece public_key) {
+TrialTokenStatus TrialToken::Extract(const std::string& token_payload,
+                                     base::StringPiece public_key,
+                                     std::string* out_token_json) {
   if (token_payload.empty()) {
-    return nullptr;
+    return TRIAL_TOKEN_STATUS_MALFORMED;
   }
 
   // Token is base64-encoded; decode first.
   std::string token_contents;
   if (!base::Base64Decode(token_payload, &token_contents)) {
-    return nullptr;
+    return TRIAL_TOKEN_STATUS_MALFORMED;
   }
 
   // Only version 2 currently supported.
   if (token_contents.length() < (kVersionOffset + kVersionSize)) {
-    return nullptr;
+    return TRIAL_TOKEN_STATUS_MALFORMED;
   }
   uint8_t version = token_contents[kVersionOffset];
   if (version != kVersion2) {
-    return nullptr;
+    return TRIAL_TOKEN_STATUS_MALFORMED;
   }
 
   // Token must be large enough to contain a version, signature, and payload
   // length.
   if (token_contents.length() < (kPayloadLengthOffset + kPayloadLengthSize)) {
-    return nullptr;
+    return TRIAL_TOKEN_STATUS_MALFORMED;
   }
 
   // Extract the length of the signed data (Big-endian).
   uint32_t payload_length;
   base::ReadBigEndian(&(token_contents[kPayloadLengthOffset]), &payload_length);
 
   // Validate that the stated length matches the actual payload length.
   if (payload_length != token_contents.length() - kPayloadOffset) {
-    return nullptr;
+    return TRIAL_TOKEN_STATUS_MALFORMED;
   }
 
   // Extract the version-specific contents of the token.
   const char* token_bytes = token_contents.data();
   base::StringPiece version_piece(token_bytes + kVersionOffset, kVersionSize);
   base::StringPiece signature(token_bytes + kSignatureOffset, kSignatureSize);
   base::StringPiece payload_piece(token_bytes + kPayloadLengthOffset,
                                   kPayloadLengthSize + payload_length);
 
   // The data which is covered by the signature is (version + length + payload).
   std::string signed_data =
       version_piece.as_string() + payload_piece.as_string();
 
   // Validate the signature on the data before proceeding.
   if (!TrialToken::ValidateSignature(signature, signed_data, public_key)) {
-    return nullptr;
+    return TRIAL_TOKEN_STATUS_INVALID_SIGNATURE;
   }
 
   // Return just the payload, as a new string.
-  return base::WrapUnique(
-      new std::string(token_contents, kPayloadOffset, payload_length));
+  *out_token_json = token_contents.substr(kPayloadOffset, payload_length);
+  return TRIAL_TOKEN_STATUS_SUCCESS;
 }
 
 std::unique_ptr<TrialToken> TrialToken::Parse(const std::string& token_json) {
   std::unique_ptr<base::DictionaryValue> datadict =
       base::DictionaryValue::From(base::JSONReader::Read(token_json));
   if (!datadict) {
     return nullptr;
   }
 
   std::string origin_string;
@@ skipping 55 matching lines @@
 }
 
 TrialToken::TrialToken(const url::Origin& origin,
                        const std::string& feature_name,
                        uint64_t expiry_timestamp)
     : origin_(origin),
       feature_name_(feature_name),
       expiry_time_(base::Time::FromDoubleT(expiry_timestamp)) {}
 
 }  // namespace content