From 1f63c850a12797c5efd2db8368ef7219ed555ce2 Mon Sep 17 00:00:00 2001
From: Magnus Ahltorp <map@kth.se>
Date: Sun, 8 Mar 2015 03:27:59 +0100
Subject: Cache SCT:s

---
 src/catlfish.erl | 43 +++++++++++++++++++++++++++++++------------
 1 file changed, 31 insertions(+), 12 deletions(-)

diff --git a/src/catlfish.erl b/src/catlfish.erl
index 3956eec..2fd9dc7 100644
--- a/src/catlfish.erl
+++ b/src/catlfish.erl
@@ -69,10 +69,30 @@ build_mtl(Timestamp, LeafCert) ->
                entry = TSE},
     serialise(MTL).
 
+calc_sct(TimestampedEntry) ->
+    plop:serialise(plop:spt(list_to_binary([<<?PROTOCOL_VERSION:8>>,
+                                            serialise_signature_type(certificate_timestamp),
+                                            serialise(TimestampedEntry)]))).
+
+get_sct(Hash, TimestampedEntry) ->
+    case application:get_env(catlfish, sctcache_root_path) of
+        {ok, RootPath} ->
+            case perm:readfile(RootPath, Hash) of
+                Contents when is_binary(Contents) ->
+                    Contents;
+                noentry ->
+                    SCT = calc_sct(TimestampedEntry),
+                    ok = perm:ensurefile_nosync(RootPath, Hash, SCT),
+                    SCT
+            end;
+        _ ->
+            SCT = calc_sct(TimestampedEntry)
+    end.
+
 -spec add_chain(binary(), [binary()]) -> nonempty_string().
 add_chain(LeafCert, CertChain) ->
     EntryHash = crypto:hash(sha256, [LeafCert | CertChain]),
-    TimestampedEntry =
+    {TimestampedEntry, Hash} =
         case plop:get(EntryHash) of
             notfound ->
                 Timestamp = plop:generate_timestamp(),
@@ -82,28 +102,27 @@ add_chain(LeafCert, CertChain) ->
                 MTL = #mtl{leaf_version = v1,
                            leaf_type = timestamped_entry,
                            entry = TSE},
+                MTLHash = ht:leaf_hash(serialise(MTL)),
                 ok = plop:add(
                        serialise_logentry(Timestamp, LeafCert, CertChain),
-                       ht:leaf_hash(serialise(MTL)),
+                       MTLHash,
                        EntryHash),
-                TSE;
-            {_Index, _MTLHash, Entry} ->
+                {TSE, MTLHash};
+            {_Index, MTLHash, Entry} ->
                 <<Timestamp:64, _LogEntry/binary>> = Entry,
                 %% TODO: Perform a costly db consistency check against
                 %% unpacked LogEntry (w/ LeafCert and CertChain)
-                #timestamped_entry{timestamp = Timestamp,
-                                   entry_type = x509_entry,
-                                   signed_entry = LeafCert}
+                {#timestamped_entry{timestamp = Timestamp,
+                                    entry_type = x509_entry,
+                                    signed_entry = LeafCert},
+                 MTLHash}
         end,
-    SCT_sig =
-        plop:spt(list_to_binary([<<?PROTOCOL_VERSION:8>>,
-                                 serialise_signature_type(certificate_timestamp),
-                                 serialise(TimestampedEntry)])),
+    SCT_sig = get_sct(Hash, TimestampedEntry),
     {[{sct_version, ?PROTOCOL_VERSION},
       {id, base64:encode(plop:get_logid())},
       {timestamp, TimestampedEntry#timestamped_entry.timestamp},
       {extensions, base64:encode(<<>>)},
-      {signature, base64:encode(plop:serialise(SCT_sig))}]}.
+      {signature, base64:encode(SCT_sig)}]}.
 
 -spec serialise_logentry(integer(), binary(), [binary()]) -> binary().
 serialise_logentry(Timestamp, LeafCert, CertChain) ->
-- 
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