1 files changed, 139 insertions, 0 deletions
diff --git a/core/block_validator.go b/core/block_validator.go
new file mode 100644
index 0000000..ae6cd4d
--- /dev/null
+++ b/core/block_validator.go
@@ -0,0 +1,139 @@
+// Copyright 2015 The go-ethereum Authors
+// This file is part of the go-ethereum library.
+//
+// The go-ethereum library is free software: you can redistribute it and/or modify
+// it under the terms of the GNU Lesser General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// The go-ethereum library is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+// GNU Lesser General Public License for more details.
+//
+// You should have received a copy of the GNU Lesser General Public License
+// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.
+
+package core
+
+import (
+	"fmt"
+
+	"github.com/ava-labs/go-ethereum/consensus"
+	"github.com/ava-labs/go-ethereum/core/state"
+	"github.com/ava-labs/go-ethereum/core/types"
+	"github.com/ava-labs/go-ethereum/params"
+)
+
+// BlockValidator is responsible for validating block headers, uncles and
+// processed state.
+//
+// BlockValidator implements Validator.
+type BlockValidator struct {
+	config *params.ChainConfig // Chain configuration options
+	bc     *BlockChain         // Canonical block chain
+	engine consensus.Engine    // Consensus engine used for validating
+}
+
+// NewBlockValidator returns a new block validator which is safe for re-use
+func NewBlockValidator(config *params.ChainConfig, blockchain *BlockChain, engine consensus.Engine) *BlockValidator {
+	validator := &BlockValidator{
+		config: config,
+		engine: engine,
+		bc:     blockchain,
+	}
+	return validator
+}
+
+// ValidateBody validates the given block's uncles and verifies the block
+// header's transaction and uncle roots. The headers are assumed to be already
+// validated at this point.
+func (v *BlockValidator) ValidateBody(block *types.Block) error {
+	// Check whether the block's known, and if not, that it's linkable
+	if v.bc.HasBlockAndState(block.Hash(), block.NumberU64()) {
+		return ErrKnownBlock
+	}
+	// Header validity is known at this point, check the uncles and transactions
+	header := block.Header()
+	if err := v.engine.VerifyUncles(v.bc, block); err != nil {
+		return err
+	}
+	if hash := types.CalcUncleHash(block.Uncles()); hash != header.UncleHash {
+		return fmt.Errorf("uncle root hash mismatch: have %x, want %x", hash, header.UncleHash)
+	}
+	if hash := types.DeriveSha(block.Transactions()); hash != header.TxHash {
+		return fmt.Errorf("transaction root hash mismatch: have %x, want %x", hash, header.TxHash)
+	}
+	if !v.bc.HasBlockAndState(block.ParentHash(), block.NumberU64()-1) {
+		if !v.bc.HasBlock(block.ParentHash(), block.NumberU64()-1) {
+			return consensus.ErrUnknownAncestor
+		}
+		return consensus.ErrPrunedAncestor
+	}
+	return nil
+}
+
+// ValidateState validates the various changes that happen after a state
+// transition, such as amount of used gas, the receipt roots and the state root
+// itself. ValidateState returns a database batch if the validation was a success
+// otherwise nil and an error is returned.
+func (v *BlockValidator) ValidateState(block *types.Block, statedb *state.StateDB, receipts types.Receipts, usedGas uint64) error {
+	header := block.Header()
+	if block.GasUsed() != usedGas {
+		return fmt.Errorf("invalid gas used (remote: %d local: %d)", block.GasUsed(), usedGas)
+	}
+	// Validate the received block's bloom with the one derived from the generated receipts.
+	// For valid blocks this should always validate to true.
+	rbloom := types.CreateBloom(receipts)
+	if rbloom != header.Bloom {
+		return fmt.Errorf("invalid bloom (remote: %x  local: %x)", header.Bloom, rbloom)
+	}
+	// Tre receipt Trie's root (R = (Tr [[H1, R1], ... [Hn, R1]]))
+	receiptSha := types.DeriveSha(receipts)
+	if receiptSha != header.ReceiptHash {
+		return fmt.Errorf("invalid receipt root hash (remote: %x local: %x)", header.ReceiptHash, receiptSha)
+	}
+	// Validate the state root against the received state root and throw
+	// an error if they don't match.
+	if root := statedb.IntermediateRoot(v.config.IsEIP158(header.Number)); header.Root != root {
+		return fmt.Errorf("invalid merkle root (remote: %x local: %x)", header.Root, root)
+	}
+	return nil
+}
+
+// CalcGasLimit computes the gas limit of the next block after parent. It aims
+// to keep the baseline gas above the provided floor, and increase it towards the
+// ceil if the blocks are full. If the ceil is exceeded, it will always decrease
+// the gas allowance.
+func CalcGasLimit(parent *types.Block, gasFloor, gasCeil uint64) uint64 {
+	// contrib = (parentGasUsed * 3 / 2) / 1024
+	contrib := (parent.GasUsed() + parent.GasUsed()/2) / params.GasLimitBoundDivisor
+
+	// decay = parentGasLimit / 1024 -1
+	decay := parent.GasLimit()/params.GasLimitBoundDivisor - 1
+
+	/*
+		strategy: gasLimit of block-to-mine is set based on parent's
+		gasUsed value.  if parentGasUsed > parentGasLimit * (2/3) then we
+		increase it, otherwise lower it (or leave it unchanged if it's right
+		at that usage) the amount increased/decreased depends on how far away
+		from parentGasLimit * (2/3) parentGasUsed is.
+	*/
+	limit := parent.GasLimit() - decay + contrib
+	if limit < params.MinGasLimit {
+		limit = params.MinGasLimit
+	}
+	// If we're outside our allowed gas range, we try to hone towards them
+	if limit < gasFloor {
+		limit = parent.GasLimit() + decay
+		if limit > gasFloor {
+			limit = gasFloor
+		}
+	} else if limit > gasCeil {
+		limit = parent.GasLimit() - decay
+		if limit < gasCeil {
+			limit = gasCeil
+		}
+	}
+	return limit
+}