From e02c0fa8088943bc995d290e58a7226f4a0ece91 Mon Sep 17 00:00:00 2001
From: obscuren <geffobscura@gmail.com>
Date: Fri, 10 Oct 2014 17:00:06 +0200
Subject: Added generic big to 256 method. Implemented new iterator

---
 ethchain/block_chain.go   | 25 ++++++++++++++-----------
 ethchain/state_manager.go |  8 +++++---
 2 files changed, 19 insertions(+), 14 deletions(-)

(limited to 'ethchain')

diff --git a/ethchain/block_chain.go b/ethchain/block_chain.go
index 113e313ac..a5dcec438 100644
--- a/ethchain/block_chain.go
+++ b/ethchain/block_chain.go
@@ -40,13 +40,11 @@ func (bc *BlockChain) Genesis() *Block {
 
 func (bc *BlockChain) NewBlock(coinbase []byte) *Block {
 	var root interface{}
-	var lastBlockTime int64
 	hash := ZeroHash256
 
 	if bc.CurrentBlock != nil {
 		root = bc.CurrentBlock.state.Trie.Root
 		hash = bc.LastBlockHash
-		lastBlockTime = bc.CurrentBlock.Time
 	}
 
 	block := CreateBlock(
@@ -61,15 +59,7 @@ func (bc *BlockChain) NewBlock(coinbase []byte) *Block {
 
 	parent := bc.CurrentBlock
 	if parent != nil {
-		diff := new(big.Int)
-
-		adjust := new(big.Int).Rsh(parent.Difficulty, 10)
-		if block.Time >= lastBlockTime+5 {
-			diff.Sub(parent.Difficulty, adjust)
-		} else {
-			diff.Add(parent.Difficulty, adjust)
-		}
-		block.Difficulty = diff
+		block.Difficulty = CalcDifficulty(block, parent)
 		block.Number = new(big.Int).Add(bc.CurrentBlock.Number, ethutil.Big1)
 		block.GasLimit = block.CalcGasLimit(bc.CurrentBlock)
 
@@ -78,6 +68,19 @@ func (bc *BlockChain) NewBlock(coinbase []byte) *Block {
 	return block
 }
 
+func CalcDifficulty(block, parent *Block) *big.Int {
+	diff := new(big.Int)
+
+	adjust := new(big.Int).Rsh(parent.Difficulty, 10)
+	if block.Time >= parent.Time+5 {
+		diff.Sub(parent.Difficulty, adjust)
+	} else {
+		diff.Add(parent.Difficulty, adjust)
+	}
+
+	return diff
+}
+
 func (bc *BlockChain) Reset() {
 	AddTestNetFunds(bc.genesisBlock)
 
diff --git a/ethchain/state_manager.go b/ethchain/state_manager.go
index 93fd1ec58..589b99ac2 100644
--- a/ethchain/state_manager.go
+++ b/ethchain/state_manager.go
@@ -346,9 +346,6 @@ func (sm *StateManager) CalculateTD(block *Block) bool {
 // an uncle or anything that isn't on the current block chain.
 // Validation validates easy over difficult (dagger takes longer time = difficult)
 func (sm *StateManager) ValidateBlock(block *Block) error {
-	// TODO
-	// 2. Check if the difficulty is correct
-
 	// Check each uncle's previous hash. In order for it to be valid
 	// is if it has the same block hash as the current
 	parent := sm.bc.GetBlock(block.PrevHash)
@@ -360,6 +357,11 @@ func (sm *StateManager) ValidateBlock(block *Block) error {
 		}
 	*/
 
+	expd := CalcDifficulty(block, parent)
+	if expd.Cmp(block.Difficulty) < 0 {
+		return fmt.Errorf("Difficulty check failed for block %v, %v", block.Difficulty, expd)
+	}
+
 	diff := block.Time - parent.Time
 	if diff < 0 {
 		return ValidationError("Block timestamp less then prev block %v (%v - %v)", diff, block.Time, sm.bc.CurrentBlock.Time)
-- 
cgit