From a0f05eac214752597707002044416bc1ef31b9a3 Mon Sep 17 00:00:00 2001
From: John Ingve Olsen <johningveolsen@gmail.com>
Date: Fri, 19 Aug 2022 15:47:43 +0200
Subject: [PATCH] convert: try to cast hash byte slice

---
 internal/proto/hotstuffpb/convert.go      | 28 +++++++++++++------
 internal/proto/hotstuffpb/convert_test.go | 34 +++++++++++++++++++++++
 2 files changed, 53 insertions(+), 9 deletions(-)

diff --git a/internal/proto/hotstuffpb/convert.go b/internal/proto/hotstuffpb/convert.go
index 5be7b43b..b2f1ed19 100644
--- a/internal/proto/hotstuffpb/convert.go
+++ b/internal/proto/hotstuffpb/convert.go
@@ -70,9 +70,10 @@ func PartialCertToProto(cert hotstuff.PartialCert) *PartialCert {
 
 // PartialCertFromProto converts a hotstuffpb.PartialCert to an ecdsa.PartialCert.
 func PartialCertFromProto(cert *PartialCert) hotstuff.PartialCert {
-	var h hotstuff.Hash
-	copy(h[:], cert.GetHash())
-	return hotstuff.NewPartialCert(QuorumSignatureFromProto(cert.GetSig()), h)
+	return hotstuff.NewPartialCert(
+		QuorumSignatureFromProto(cert.GetSig()),
+		convertHash(cert.GetHash()),
+	)
 }
 
 // QuorumCertToProto converts a consensus.QuorumCert to a hotstuffpb.QuorumCert.
@@ -87,9 +88,11 @@ func QuorumCertToProto(qc hotstuff.QuorumCert) *QuorumCert {
 
 // QuorumCertFromProto converts a hotstuffpb.QuorumCert to an ecdsa.QuorumCert.
 func QuorumCertFromProto(qc *QuorumCert) hotstuff.QuorumCert {
-	var h hotstuff.Hash
-	copy(h[:], qc.GetHash())
-	return hotstuff.NewQuorumCert(QuorumSignatureFromProto(qc.GetSig()), hotstuff.View(qc.GetView()), h)
+	return hotstuff.NewQuorumCert(
+		QuorumSignatureFromProto(qc.GetSig()),
+		hotstuff.View(qc.GetView()),
+		convertHash(qc.GetHash()),
+	)
 }
 
 // ProposalToProto converts a ProposeMsg to a protobuf message.
@@ -127,10 +130,8 @@ func BlockToProto(block *hotstuff.Block) *Block {
 
 // BlockFromProto converts a hotstuffpb.Block to a consensus.Block.
 func BlockFromProto(block *Block) *hotstuff.Block {
-	var p hotstuff.Hash
-	copy(p[:], block.GetParent())
 	return hotstuff.NewBlock(
-		p,
+		convertHash(block.GetParent()),
 		QuorumCertFromProto(block.GetQC()),
 		unsafeBytesToString(block.GetCommand()),
 		hotstuff.View(block.GetView()),
@@ -225,6 +226,15 @@ func SyncInfoToProto(syncInfo hotstuff.SyncInfo) *SyncInfo {
 	return m
 }
 
+func convertHash(b []byte) (h hotstuff.Hash) {
+	if len(b) < len(h) {
+		copy(h[:], b)
+	} else {
+		h = *(*hotstuff.Hash)(b)
+	}
+	return h
+}
+
 func unsafeStringToBytes(s string) []byte {
 	if s == "" {
 		return []byte{}
diff --git a/internal/proto/hotstuffpb/convert_test.go b/internal/proto/hotstuffpb/convert_test.go
index 8540d6a3..68121cf4 100644
--- a/internal/proto/hotstuffpb/convert_test.go
+++ b/internal/proto/hotstuffpb/convert_test.go
@@ -2,6 +2,8 @@ package hotstuffpb
 
 import (
 	"bytes"
+	"crypto/rand"
+	"io"
 	"testing"
 
 	"github.com/relab/hotstuff"
@@ -95,3 +97,35 @@ func TestConvertTimeoutCertBLS12(t *testing.T) {
 		t.Fatal("Failed to verify timeout cert")
 	}
 }
+
+func BenchmarkConvertHash(b *testing.B) {
+	s := make([]byte, 32)
+	_, err := io.ReadFull(rand.Reader, s)
+	if err != nil {
+		b.Fatal(err)
+	}
+
+	var h hotstuff.Hash
+
+	for i := 0; i < b.N; i++ {
+		h = convertHash(s)
+	}
+
+	_ = h
+}
+
+func BenchmarkCopyHash(b *testing.B) {
+	s := make([]byte, 32)
+	_, err := io.ReadFull(rand.Reader, s)
+	if err != nil {
+		b.Fatal(err)
+	}
+
+	var h hotstuff.Hash
+
+	for i := 0; i < b.N; i++ {
+		copy(h[:], s)
+	}
+
+	_ = h
+}