Adds a function for encoding a Merkle tree leaf in TLS wire format.

net/cert/ct_serialization.cc

Index: net/cert/ct_serialization.cc
diff --git a/net/cert/ct_serialization.cc b/net/cert/ct_serialization.cc
index 2de83087260f8828a81a44e65f719eeb5bd8ebe9..d64c839f2ed95c61555ce85afe56ebffb340d7af 100644
--- a/net/cert/ct_serialization.cc
+++ b/net/cert/ct_serialization.cc
@@ -19,22 +19,25 @@ namespace ct {
 namespace {
 
 // Note: length is always specified in bytes.
-// Signed Certificate Timestamp (SCT) Version length
+// CT protocol version length
 const size_t kVersionLength = 1;
+const size_t kSha256HashLength = 32;

[Eran Messeri, 2016/05/04 10:29:23]

This is redundant, you can use the definition from
https://code.google.com/p/chromium/codesearch#chromium/src/crypto/sha2.h&q=cr...

[Rob Percival, 2016/05/05 15:45:31]

Done.

 
-// Members of a V1 SCT
-const size_t kLogIdLength = 32;
+// Common V1 struct members
 const size_t kTimestampLength = 8;
+const size_t kLogEntryTypeLength = 2;
+const size_t kAsn1CertificateLengthBytes = 3;
+const size_t kTbsCertificateLengthBytes = 3;
 const size_t kExtensionsLengthBytes = 2;
+
+// Members of a V1 SCT
+const size_t kLogIdLength = kSha256HashLength;
 const size_t kHashAlgorithmLength = 1;
 const size_t kSigAlgorithmLength = 1;
 const size_t kSignatureLengthBytes = 2;
 
 // Members of the digitally-signed struct of a V1 SCT
 const size_t kSignatureTypeLength = 1;
-const size_t kLogEntryTypeLength = 2;
-const size_t kAsn1CertificateLengthBytes = 3;
-const size_t kTbsCertificateLengthBytes = 3;
 
 const size_t kSCTListLengthBytes = 2;
 const size_t kSerializedSCTLengthBytes = 2;
@@ -42,6 +45,10 @@ const size_t kSerializedSCTLengthBytes = 2;
 // Members of digitally-signed struct of a STH
 const size_t kTreeSizeLength = 8;
 
+// Members of a V1 MerkleTreeLeaf
+const size_t kMerkleLeafTypeLength = 1;
+const size_t kIssuerKeyHashLength = kSha256HashLength;
+
 enum SignatureType {
   SIGNATURE_TYPE_CERTIFICATE_TIMESTAMP = 0,
   TREE_HASH = 1,
@@ -254,7 +261,7 @@ bool EncodePrecertLogEntry(const LogEntry& input, std::string* output) {
   WriteEncodedBytes(
       base::StringPiece(
           reinterpret_cast<const char*>(input.issuer_key_hash.data),
-          kLogIdLength),
+          kIssuerKeyHashLength),
       output);
   return WriteVariableBytes(kTbsCertificateLengthBytes,
                             input.tbs_certificate, output);
@@ -335,6 +342,19 @@ static void WriteTimeSinceEpoch(const base::Time& timestamp,
   WriteUint(kTimestampLength, time_since_epoch.InMilliseconds(), output);
 }
 
+bool EncodeTreeLeaf(const MerkleTreeLeaf& leaf, std::string* output) {
+  WriteUint(kVersionLength, MerkleTreeLeaf::VERSION_1, output);
+  WriteUint(kMerkleLeafTypeLength, MerkleTreeLeaf::TYPE_TIMESTAMPED_ENTRY,
+            output);
+  WriteTimeSinceEpoch(leaf.timestamp, output);
+  if (!EncodeLogEntry(leaf.log_entry, output))
+      return false;
+  if (!WriteVariableBytes(kExtensionsLengthBytes, leaf.extensions, output))
+      return false;
+
+  return true;
+}
+
 bool EncodeV1SCTSignedData(const base::Time& timestamp,
                            const std::string& serialized_log_entry,
                            const std::string& extensions,