Certificate Transparency: Start tracking logs' state

net/cert/signed_tree_head.h

 // 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.
 
 #ifndef NET_CERT_SIGNED_TREE_HEAD_H_
 #define NET_CERT_SIGNED_TREE_HEAD_H_
 
 #include <stdint.h>
 
 #include <iosfwd>
@@ skipping 32 matching lines @@
   base::Time timestamp;
   uint64_t tree_size;
   char sha256_root_hash[kSthRootHashLength];
   DigitallySigned signature;
 
   // Added in RFC6962-bis, Appendix A. Needed to identify which log
   // this STH belongs to.
   std::string log_id;
 };
 
+// Two STHs are considered equal if they are from the same log and have matching
+// timestamps, since RFC6962 forbids a log from issuing two different STHs with
+// the same timestamp.
+NET_EXPORT bool operator==(const SignedTreeHead& sth1,
+                           const SignedTreeHead& sth2);
+NET_EXPORT bool operator!=(const SignedTreeHead& sth1,
+                           const SignedTreeHead& sth2);
+
 NET_EXPORT void PrintTo(const SignedTreeHead& sth, std::ostream* os);
 
 }  // namespace ct
 
 }  // namespace net
 
-#endif
+#endif  // NET_CERT_SIGNED_TREE_HEAD_H_