[Downloads/History] Comply with RFC 4122 when generating GUIDs.

components/history/core/browser/history_backend_db_unittest.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.
 
 // History unit tests come in two flavors:
 //
 // 1. The more complicated style is that the unit test creates a full history
 //    service. This spawns a background thread for the history backend, and
 //    all communication is asynchronous. This is useful for testing more
 //    complicated things or end-to-end behavior.
@@ skipping 501 matching lines @@
     {
       sql::Statement s(db.GetUniqueStatement(
           "SELECT mime_type, original_mime_type from downloads"));
       EXPECT_TRUE(s.Step());
       EXPECT_EQ(std::string(), s.ColumnString(0));
       EXPECT_EQ(std::string(), s.ColumnString(1));
     }
   }
 }
 
+bool IsValidRFC4122Ver4GUID(const std::string& guid) {
+  // base::IsValidGUID() doesn't restrict its validation to version (or subtype)
+  // 4 GUIDs as described in RFC 4122. So we check if base::IsValidGUID() thinks
+  // it's a valid GUID first, and then check the additional constraints.
+  //
+  // * Bits 4-7 of time_hi_and_version should be set to 0b0100 == 4
+  //   => guid[14] == '4'
+  //
+  // * Bits 6-7 of clk_seq_hi_res should be set to 0b10
+  //   => guid[19] in {'8','9','A','B'}
+  //
+  // * All other bits should be random or pseudo random.
+  //   => http://dilbert.com/strip/2001-10-25
+  return base::IsValidGUID(guid) && guid[14] == '4' &&
+         (guid[19] == '8' || guid[19] == '9' || guid[19] == 'A' ||
+          guid[19] == 'B');
+}
+
 TEST_F(HistoryBackendDBTest, MigrateHashHttpMethodAndGenerateGuids) {
   const size_t kDownloadCount = 100;
   ASSERT_NO_FATAL_FAILURE(CreateDBVersion(29));
   base::Time now(base::Time::Now());
   {
     sql::Connection db;
     ASSERT_TRUE(db.Open(history_dir_.Append(kHistoryFilename)));
 
     // In testing, it appeared that constructing a query where all rows are
     // specified (i.e. looks like "INSERT INTO foo (...) VALUES (...),(...)")
@@ skipping 44 matching lines @@
       sql::Statement s(db.GetUniqueStatement(
           "SELECT value FROM meta WHERE key = 'version'"));
       EXPECT_TRUE(s.Step());
       EXPECT_EQ(cur_version, s.ColumnInt(0));
     }
     {
       sql::Statement s(db.GetUniqueStatement("SELECT guid from downloads"));
       std::unordered_set<std::string> guids;
       while (s.Step()) {
         std::string guid = s.ColumnString(0);
-        EXPECT_TRUE(base::IsValidGUID(guid));
+        EXPECT_TRUE(IsValidRFC4122Ver4GUID(guid));
         EXPECT_EQ(guid, base::ToUpperASCII(guid));
         guids.insert(guid);
       }
       EXPECT_TRUE(s.Succeeded());
       EXPECT_EQ(kDownloadCount, guids.size());
     }
   }
 }
 
 TEST_F(HistoryBackendDBTest, DownloadCreateAndQuery) {
@@ skipping 419 matching lines @@
       // Current browser version must be already higher than 28.
       ASSERT_LT(28, HistoryDatabase::GetCurrentVersion());
       // Expect that version in DB remains the same.
       EXPECT_EQ(28, meta.GetVersionNumber());
     }
   }
 }
 
 }  // namespace
 }  // namespace history