From 670b215e0ad78409e3228211685b4b2ce8d65915 Mon Sep 17 00:00:00 2001
From: arnaucube <arnaucube@gmail.com>
Date: Mon, 8 Apr 2019 20:58:32 +0200
Subject: [PATCH] add block.CalculateHash, fix SignBlock, started
 CreateGenesis, started VerifyBlock

---
 core/block.go      |  9 +++++++++
 core/blockchain.go | 30 +++++++++++++++++++++++++++++-
 node/node.go       | 35 +++++++++++++++++++++++++++++++----
 node/node_test.go  |  6 ++++--
 4 files changed, 73 insertions(+), 7 deletions(-)

diff --git a/core/block.go b/core/block.go
index f69b59e..9250c69 100644
--- a/core/block.go
+++ b/core/block.go
@@ -35,10 +35,19 @@ func (block Block) Copy() *Block {
 
 // Bytes outputs a byte array containing the data of the Block
 func (blk Block) Bytes() []byte {
+	// TODO add parser, to use minimum amount of bytes
 	b, _ := json.Marshal(blk)
 	return b
 }
 
+func (block *Block) CalculateHash() {
+	blockCopy := block.Copy()
+	blockCopy.Hash = Hash{}
+	blockCopy.Signature = []byte{}
+	hash := HashBytes(blockCopy.Bytes())
+	block.Hash = hash
+}
+
 func (blk *Block) GetNonce() uint64 {
 	return blk.Nonce
 }
diff --git a/core/blockchain.go b/core/blockchain.go
index 9d3b4b2..e158f6d 100644
--- a/core/blockchain.go
+++ b/core/blockchain.go
@@ -4,6 +4,7 @@ import (
 	"bytes"
 	"crypto/ecdsa"
 	"errors"
+	"fmt"
 
 	"github.com/arnaucube/slowlorisdb/db"
 )
@@ -91,7 +92,7 @@ func (bc *Blockchain) GetPrevBlock(hash Hash) (*Block, error) {
 	return prevBlock, nil
 }
 
-func (bc *Blockchain) VerifyBlockSignature(block *Block) bool {
+func (bc *Blockchain) verifyBlockSignature(block *Block) bool {
 	// check if the signer is one of the blockchain.AuthMiners
 	signerIsMiner := false
 	for _, pubK := range bc.PoA.AuthMiners {
@@ -113,6 +114,33 @@ func (bc *Blockchain) VerifyBlockSignature(block *Block) bool {
 	return VerifySignature(block.MinerPubK, block.Hash[:], *sig)
 }
 
+func (bc *Blockchain) VerifyBlock(block *Block) bool {
+	// verify block signature
+	if !bc.verifyBlockSignature(block) {
+		return false
+	}
+
+	// verify timestamp
+
+	// verify prev hash
+	// check that the block.PrevHash is the blockchain current last block
+	fmt.Println(block.PrevHash)
+	fmt.Println(bc.LastBlock.Hash)
+	if !bytes.Equal(block.PrevHash[:], bc.LastBlock.Hash[:]) {
+		return false
+	}
+
+	// verify block height
+	// check that the block height is the last block + 1
+	if block.Height != bc.LastBlock.Height+1 {
+		return false
+	}
+
+	// verify block transactions
+
+	return true
+}
+
 // func (bc *Blockchain) Mint(toAddr Address, amount uint64) error {
 //         fromAddr := Address(HashBytes([]byte("mint")))
 //         out :=
diff --git a/node/node.go b/node/node.go
index 2bcddba..a960c9f 100644
--- a/node/node.go
+++ b/node/node.go
@@ -32,8 +32,13 @@ func (node *Node) Sign(m []byte) (*core.Signature, error) {
 	return core.Sign(node.PrivK, m)
 }
 
-func (node *Node) SignBlock(block *core.Block) (*core.Signature, error) {
-	return core.Sign(node.PrivK, block.Hash[:])
+func (node *Node) SignBlock(block *core.Block) error {
+	sig, err := core.Sign(node.PrivK, block.Hash[:])
+	if err != nil {
+		return err
+	}
+	block.Signature = sig.Bytes()
+	return nil
 }
 
 func (node *Node) AddToPendingTxs(tx core.Tx) {
@@ -42,15 +47,17 @@ func (node *Node) AddToPendingTxs(tx core.Tx) {
 
 func (node *Node) BlockFromPendingTxs() (*core.Block, error) {
 	block := node.NewBlock(node.PendingTxs)
+	block.PrevHash = node.Bc.LastBlock.Hash
 	err := block.CalculatePoW(node.Bc.Difficulty)
 	if err != nil {
 		return nil, err
 	}
-	sig, err := node.SignBlock(block)
+	err = node.SignBlock(block)
 	if err != nil {
 		return nil, err
 	}
-	block.Signature = sig.Bytes()
+	block.CalculateHash()
+
 	return block, nil
 }
 
@@ -68,3 +75,23 @@ func (node *Node) NewBlock(txs []core.Tx) *core.Block {
 	}
 	return block
 }
+
+func (node *Node) CreateGenesis() (*core.Block, error) {
+	block := &core.Block{
+		Height:    uint64(0),
+		PrevHash:  core.Hash{},
+		Txs:       []core.Tx{},
+		Miner:     node.Addr,
+		MinerPubK: &node.PrivK.PublicKey,
+		Timestamp: time.Now(),
+		Nonce:     uint64(0),
+		Hash:      core.Hash{},
+		Signature: []byte{},
+	}
+
+	err := node.SignBlock(block)
+	if err != nil {
+		return nil, err
+	}
+	return block, nil
+}
diff --git a/node/node_test.go b/node/node_test.go
index 7a31e7d..0f0395f 100644
--- a/node/node_test.go
+++ b/node/node_test.go
@@ -1,6 +1,7 @@
 package node
 
 import (
+	"fmt"
 	"io/ioutil"
 	"testing"
 
@@ -67,8 +68,9 @@ func TestBlockFromPendingTxs(t *testing.T) {
 	node.AddToPendingTxs(*tx)
 	block, err := node.BlockFromPendingTxs()
 	assert.Nil(t, err)
+	fmt.Println("h", block.Hash)
 	assert.True(t, core.CheckBlockPoW(block, node.Bc.Difficulty))
-	assert.True(t, node.Bc.VerifyBlockSignature(block))
+	assert.True(t, node.Bc.VerifyBlock(block))
 }
 
 func TestBlockFromPendingTxsIteration(t *testing.T) {
@@ -94,5 +96,5 @@ func TestBlockFromPendingTxsIteration(t *testing.T) {
 	block, err := node.BlockFromPendingTxs()
 	assert.Nil(t, err)
 	assert.True(t, core.CheckBlockPoW(block, node.Bc.Difficulty))
-	assert.True(t, node.Bc.VerifyBlockSignature(block))
+	assert.True(t, node.Bc.VerifyBlock(block))
 }