From 76a39dde8dcaf16c0c410a2e091dc7d0573962c7 Mon Sep 17 00:00:00 2001
From: Edward Mack <ed@edwardmack.com>
Date: Wed, 18 Sep 2019 20:42:04 +0200
Subject: [PATCH] p2p, add Block Announce Network Message (#296)

- Added BlockHeaderMessage type
- Created Encode function for BlockHeaderMessage
- Created Decode function for BlockHeaderMessage
- Created String function for BlockHeaderMessage
- Created TestEncodeBlockAnnounceMessage test
- Created TestDecodeBlockAnnounceMessage test
---
 p2p/message.go      | 27 +++++++++++++++
 p2p/message_test.go | 84 +++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 111 insertions(+)

diff --git a/p2p/message.go b/p2p/message.go
index 3f8fca0208..6479b3ba34 100644
--- a/p2p/message.go
+++ b/p2p/message.go
@@ -256,6 +256,32 @@ func (bm *BlockRequestMessage) Decode(r io.Reader) error {
 	return nil
 }
 
+type BlockHeaderMessage common.BlockHeader
+
+// string formats a BlockHeaderMessage as a string
+func (bhm *BlockHeaderMessage) String() string {
+	return fmt.Sprintf("BlockHeaderMessage ParentHash=0x%x Number=%d StateRoot=0x%x ExtrinsicsRoot=0x%x Digest=0x%x",
+		bhm.ParentHash,
+		bhm.Number,
+		bhm.StateRoot,
+		bhm.ExtrinsicsRoot,
+		bhm.Digest)
+}
+
+func (bhm *BlockHeaderMessage) Encode() ([]byte, error) {
+	enc, err := scale.Encode(bhm)
+	if err != nil {
+		return enc, err
+	}
+	return append([]byte{BlockAnnounceMsgType}, enc...), nil
+}
+
+//Decodes the message into a BlockHeaderMessage, it assumes the type byte has been removed
+func (bhm *BlockHeaderMessage) Decode(msg []byte) error {
+	_, err := scale.Decode(msg, bhm)
+	return err
+}
+
 type BlockResponseMessage struct {
 	Id   uint64
 	Data []byte // TODO: change this to BlockData type
@@ -333,4 +359,5 @@ func readHash(r io.Reader) (common.Hash, error) {
 	h := [32]byte{}
 	copy(h[:], buf)
 	return common.Hash(h), nil
+
 }
diff --git a/p2p/message_test.go b/p2p/message_test.go
index 84e52bbd12..3e0538398e 100644
--- a/p2p/message_test.go
+++ b/p2p/message_test.go
@@ -18,6 +18,7 @@ package p2p
 
 import (
 	"bytes"
+	"math/big"
 	"reflect"
 	"testing"
 
@@ -340,6 +341,7 @@ func TestEncodeBlockRequestMessage_NoOptionals(t *testing.T) {
 
 func TestDecodeBlockRequestMessage_NoOptionals(t *testing.T) {
 	encMsg, err := common.HexToBytes("0x0107000000000000000100dcd1346701ca8396496e52aa2785b1748deb6db09551b72159dcb3e08991025b000100")
+
 	if err != nil {
 		t.Fatal(err)
 	}
@@ -374,6 +376,7 @@ func TestDecodeBlockRequestMessage_NoOptionals(t *testing.T) {
 
 func TestEncodeBlockResponseMessage(t *testing.T) {
 	expected, err := common.HexToBytes("0x02070000000000000000")
+
 	if err != nil {
 		t.Fatal(err)
 	}
@@ -417,3 +420,84 @@ func TestDecodeBlockResponseMessage(t *testing.T) {
 		t.Fatalf("Fail: got %v expected %v", m, expected)
 	}
 }
+
+func TestEncodeBlockAnnounceMessage(t *testing.T) {
+	// this value is a concatenation of:
+	//  message type:  byte(3)
+	//  ParentHash: Hash: 0x4545454545454545454545454545454545454545454545454545454545454545
+	//	Number: *big.Int // block number: 1
+	//	StateRoot:  Hash: 0xb3266de137d20a5d0ff3a6401eb57127525fd9b2693701f0bf5a8a853fa3ebe0
+	//	ExtrinsicsRoot: Hash: 0x03170a2e7597b7b7e3d84c05391d139a62b157e78786d8c082f29dcf4c111314
+	//	Digest: []byte
+
+	//                                    mtparenthash                                                      bnstateroot                                                       extrinsicsroot                                                  di
+	expected, err := common.HexToBytes("0x03454545454545454545454545454545454545454545454545454545454545454504b3266de137d20a5d0ff3a6401eb57127525fd9b2693701f0bf5a8a853fa3ebe003170a2e7597b7b7e3d84c05391d139a62b157e78786d8c082f29dcf4c11131400")
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	parentHash, err := common.HexToHash("0x4545454545454545454545454545454545454545454545454545454545454545")
+	if err != nil {
+		t.Fatal(err)
+	}
+	stateRoot, err := common.HexToHash("0xb3266de137d20a5d0ff3a6401eb57127525fd9b2693701f0bf5a8a853fa3ebe0")
+	if err != nil {
+		t.Fatal(err)
+	}
+	extrinsicsRoot, err := common.HexToHash("0x03170a2e7597b7b7e3d84c05391d139a62b157e78786d8c082f29dcf4c111314")
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	bhm := &BlockHeaderMessage{
+		ParentHash:     parentHash,
+		Number:         big.NewInt(1),
+		StateRoot:      stateRoot,
+		ExtrinsicsRoot: extrinsicsRoot,
+		Digest:         []byte{},
+	}
+	encMsg, err := bhm.Encode()
+	if err != nil {
+		t.Fatal(err)
+	}
+	if !bytes.Equal(encMsg, expected) {
+		t.Fatalf("Fail: got %x expected %x", encMsg, expected)
+	}
+}
+
+func TestDecodeBlockAnnounceMessage(t *testing.T) {
+	announceMessage, err := common.HexToBytes("0x454545454545454545454545454545454545454545454545454545454545454504b3266de137d20a5d0ff3a6401eb57127525fd9b2693701f0bf5a8a853fa3ebe003170a2e7597b7b7e3d84c05391d139a62b157e78786d8c082f29dcf4c11131400")
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	bhm := new(BlockHeaderMessage)
+	err = bhm.Decode(announceMessage)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	parentHash, err := common.HexToHash("0x4545454545454545454545454545454545454545454545454545454545454545")
+	if err != nil {
+		t.Fatal(err)
+	}
+	stateRoot, err := common.HexToHash("0xb3266de137d20a5d0ff3a6401eb57127525fd9b2693701f0bf5a8a853fa3ebe0")
+	if err != nil {
+		t.Fatal(err)
+	}
+	extrinsicsRoot, err := common.HexToHash("0x03170a2e7597b7b7e3d84c05391d139a62b157e78786d8c082f29dcf4c111314")
+	if err != nil {
+		t.Fatal(err)
+	}
+	expected := &BlockHeaderMessage{
+		ParentHash:     parentHash,
+		Number:         big.NewInt(1),
+		StateRoot:      stateRoot,
+		ExtrinsicsRoot: extrinsicsRoot,
+		Digest:         []byte{},
+	}
+
+	if !reflect.DeepEqual(bhm, expected) {
+		t.Fatalf("Fail: got %v expected %v", bhm, expected)
+	}
+}