From 2105a06a266c945fe79de1f71cca5efcafaee083 Mon Sep 17 00:00:00 2001
From: Andrey Samokhvalov <andrew.shvv@gmail.com>
Date: Sun, 19 Mar 2017 21:37:15 +0300
Subject: [PATCH] channeldb: add ability to store empty auth proof

In case if the channel shouldn't be announced to the rest of the network
the proof, which is needed to announce the channel, will not be
populated, fot that reason the ability to store the empty proof has
been added.
---
 channeldb/graph.go | 45 +++++++++++++++++++++++++++++++++++----------
 1 file changed, 35 insertions(+), 10 deletions(-)

diff --git a/channeldb/graph.go b/channeldb/graph.go
index bde130b2..fa7b35f2 100644
--- a/channeldb/graph.go
+++ b/channeldb/graph.go
@@ -1093,6 +1093,15 @@ type ChannelAuthProof struct {
 	BitcoinSig2 *btcec.Signature
 }
 
+// IsEmpty check is the authentication proof is empty Proof is empty if at
+// least one of the signatures are equal to nil.
+func (p *ChannelAuthProof) IsEmpty() bool {
+	return p.NodeSig1 == nil ||
+		p.NodeSig2 == nil ||
+		p.BitcoinSig1 == nil ||
+		p.BitcoinSig2 == nil
+}
+
 // ChannelEdgePolicy represents a *directed* edge within the channel graph. For
 // each channel in the database, there are two distinct edges: one for each
 // possible direction of travel along the channel. The edges themselves hold
@@ -1477,16 +1486,24 @@ func putChanEdgeInfo(edgeIndex *bolt.Bucket, edgeInfo *ChannelEdgeInfo, chanID [
 	}
 
 	authProof := edgeInfo.AuthProof
-	if err := wire.WriteVarBytes(&b, 0, authProof.NodeSig1.Serialize()); err != nil {
+	var nodeSig1, nodeSig2, bitcoinSig1, bitcoinSig2 []byte
+	if authProof != nil {
+		nodeSig1 = authProof.NodeSig1.Serialize()
+		nodeSig2 = authProof.NodeSig2.Serialize()
+		bitcoinSig1 = authProof.BitcoinSig1.Serialize()
+		bitcoinSig2 = authProof.BitcoinSig2.Serialize()
+	}
+
+	if err := wire.WriteVarBytes(&b, 0, nodeSig1); err != nil {
 		return err
 	}
-	if err := wire.WriteVarBytes(&b, 0, authProof.NodeSig2.Serialize()); err != nil {
+	if err := wire.WriteVarBytes(&b, 0, nodeSig2); err != nil {
 		return err
 	}
-	if err := wire.WriteVarBytes(&b, 0, authProof.BitcoinSig1.Serialize()); err != nil {
+	if err := wire.WriteVarBytes(&b, 0, bitcoinSig1); err != nil {
 		return err
 	}
-	if err := wire.WriteVarBytes(&b, 0, authProof.BitcoinSig2.Serialize()); err != nil {
+	if err := wire.WriteVarBytes(&b, 0, bitcoinSig2); err != nil {
 		return err
 	}
 
@@ -1552,7 +1569,7 @@ func deserializeChanEdgeInfo(r io.Reader) (*ChannelEdgeInfo, error) {
 		return nil, err
 	}
 
-	edgeInfo.AuthProof = &ChannelAuthProof{}
+	proof := &ChannelAuthProof{}
 
 	readSig := func() (*btcec.Signature, error) {
 		sigBytes, err := wire.ReadVarBytes(r, 0, 80, "sigs")
@@ -1560,26 +1577,34 @@ func deserializeChanEdgeInfo(r io.Reader) (*ChannelEdgeInfo, error) {
 			return nil, err
 		}
 
-		return btcec.ParseSignature(sigBytes, btcec.S256())
+		if len(sigBytes) != 0 {
+			return btcec.ParseSignature(sigBytes, btcec.S256())
+		}
+
+		return nil, nil
 	}
 
-	edgeInfo.AuthProof.NodeSig1, err = readSig()
+	proof.NodeSig1, err = readSig()
 	if err != nil {
 		return nil, err
 	}
-	edgeInfo.AuthProof.NodeSig2, err = readSig()
+	proof.NodeSig2, err = readSig()
 	if err != nil {
 		return nil, err
 	}
-	edgeInfo.AuthProof.BitcoinSig1, err = readSig()
+	proof.BitcoinSig1, err = readSig()
 	if err != nil {
 		return nil, err
 	}
-	edgeInfo.AuthProof.BitcoinSig2, err = readSig()
+	proof.BitcoinSig2, err = readSig()
 	if err != nil {
 		return nil, err
 	}
 
+	if !proof.IsEmpty() {
+		edgeInfo.AuthProof = proof
+	}
+
 	edgeInfo.ChannelPoint = wire.OutPoint{}
 	if err := readOutpoint(r, &edgeInfo.ChannelPoint); err != nil {
 		return nil, err