From c6e6be4e71b569fc8da3c6a959c9dd75bc691187 Mon Sep 17 00:00:00 2001
From: Adit Sachde <23707194+aditsachde@users.noreply.github.com>
Date: Sat, 3 Aug 2024 12:56:10 -0700
Subject: [PATCH] encode fingerprint length correctly

---
 internal/sunlight/tile_ol.go | 8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/internal/sunlight/tile_ol.go b/internal/sunlight/tile_ol.go
index aaa01af..f87702b 100644
--- a/internal/sunlight/tile_ol.go
+++ b/internal/sunlight/tile_ol.go
@@ -169,10 +169,11 @@ func ReadTileLeaf(tile []byte) (e *LogEntry, rest []byte, err error) {
 	}
 
 	// look at first byte to determine the length of the chain
-	var fingerprintCount uint16
-	if !s.ReadUint16(&fingerprintCount) {
+	var fingerprintBytes uint16
+	if !s.ReadUint16(&fingerprintBytes) {
 		return nil, s, fmt.Errorf("invalid data tile precert_entry")
 	}
+	var fingerprintCount = fingerprintBytes / 32
 	// then, try to read out that many fingerprints
 	e.ChainFp = make([][32]byte, 0, fingerprintCount)
 	for i := uint16(0); i < fingerprintCount; i++ {
@@ -217,7 +218,8 @@ func AppendTileLeaf(t []byte, e *LogEntry) []byte {
 			b.AddBytes(e.PreCertificate)
 		})
 	}
-	b.AddUint16(uint16(len(e.ChainFp)))
+	// A Fingerprint is always 32 bytes and the length is the total number of bytes
+	b.AddUint16(uint16(len(e.ChainFp) * 32))
 	for _, fingerprint := range e.ChainFp {
 		b.AddBytes(fingerprint[:])
 	}