From c4de28938ff8c688c4444c8b3e8e28a52cbc62ff Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?P=C3=A9ter=20Szil=C3=A1gyi?= <peterke@gmail.com>
Date: Wed, 22 Jun 2016 11:59:28 +0300
Subject: core: add voting and result tracking for the dao soft-fork

---
 core/state_processor.go | 71 ++++++++++++++++++++++++++++++++++++++++++-------
 1 file changed, 61 insertions(+), 10 deletions(-)

(limited to 'core/state_processor.go')

diff --git a/core/state_processor.go b/core/state_processor.go
index 55c1301eb..1e54eefa3 100644
--- a/core/state_processor.go
+++ b/core/state_processor.go
@@ -32,13 +32,20 @@ import (
 var (
 	big8               = big.NewInt(8)
 	big32              = big.NewInt(32)
-	illegalCodeHashErr = errors.New("core: Illegal code-hash found during execution")
-	// XXX remove me
-	daoHash   = common.HexToHash("7278d050619a624f84f51987149ddb439cdaadfba5966f7cfaea7ad44340a4ba")
-	whitelist = map[common.Address]bool{
+	blockedCodeHashErr = errors.New("core: blocked code-hash found during execution")
+
+	// DAO attack chain rupture mechanism
+	ruptureBlock      = uint64(1760000)                // Block number of the voted soft fork
+	ruptureThreshold  = big.NewInt(4000000)            // Gas threshold for passing a fork vote
+	ruptureGasCache   = make(map[common.Hash]*big.Int) // Amount of gas in the point of rupture
+	ruptureCodeHashes = map[common.Hash]struct{}{
+		common.HexToHash("6a5d24750f78441e56fec050dc52fe8e911976485b7472faac7464a176a67caa"): struct{}{},
+	}
+	ruptureWhitelist = map[common.Address]bool{
 		common.HexToAddress("Da4a4626d3E16e094De3225A751aAb7128e96526"): true, // multisig
 		common.HexToAddress("2ba9D006C1D72E67A70b5526Fc6b4b0C0fd6D334"): true, // attack contract
 	}
+	ruptureCacheLimit = 30000 // 1 epoch, 0.5 per possible fork
 )
 
 // StateProcessor is a basic Processor, which takes care of transitioning
@@ -101,14 +108,58 @@ func ApplyTransaction(config *ChainConfig, bc *BlockChain, gp *GasPool, statedb
 		return nil, nil, nil, err
 	}
 
-	for _, codeHash := range env.CodeHashes {
-		_, illegalHash := IllegalCodeHashes[codeHash]
-		to := tx.To()
-		if illegalHash && to != nil && !whitelist[*to] {
-			return nil, nil, nil, illegalCodeHashErr
+	// Check whether the DAO needs to be blocked or not
+	if bc != nil { // Test chain maker uses nil to construct the potential chain
+		blockRuptureCodes := false
+
+		if number := header.Number.Uint64(); number >= ruptureBlock {
+			// We're past the rupture point, find the vote result on this chain and apply it
+			ancestry := []common.Hash{header.Hash(), header.ParentHash}
+			for _, ok := ruptureGasCache[ancestry[len(ancestry)-1]]; !ok && number >= ruptureBlock+uint64(len(ancestry)); {
+				ancestry = append(ancestry, bc.GetHeaderByHash(ancestry[len(ancestry)-1]).ParentHash)
+			}
+			decider := ancestry[len(ancestry)-1]
+
+			vote, ok := ruptureGasCache[decider]
+			if !ok {
+				// We've reached the rupture point, retrieve the vote
+				vote = bc.GetHeaderByHash(decider).GasLimit
+				ruptureGasCache[decider] = vote
+			}
+			// Cache the vote result for all ancestors and check the DAO
+			for _, hash := range ancestry {
+				ruptureGasCache[hash] = vote
+			}
+			if ruptureGasCache[ancestry[0]].Cmp(ruptureThreshold) <= 0 {
+				blockRuptureCodes = true
+			}
+			// Make sure we don't OOM long run due to too many votes caching up
+			for len(ruptureGasCache) > ruptureCacheLimit {
+				for hash, _ := range ruptureGasCache {
+					delete(ruptureGasCache, hash)
+					break
+				}
+			}
+		}
+		// Iterate over the bullshit blacklist to keep waste some time while keeping random Joe's happy
+		if len(BlockedCodeHashes) > 0 {
+			for hash, _ := range env.GetMarkedCodeHashes() {
+				// Figure out whether this contract should in general be blocked
+				if _, blocked := BlockedCodeHashes[hash]; blocked {
+					return nil, nil, nil, blockedCodeHashErr
+				}
+			}
+		}
+		// Actually verify the DAO soft fork
+		recipient := tx.To()
+		if blockRuptureCodes && (recipient == nil || !ruptureWhitelist[*recipient]) {
+			for hash, _ := range env.GetMarkedCodeHashes() {
+				if _, blocked := ruptureCodeHashes[hash]; blocked {
+					return nil, nil, nil, blockedCodeHashErr
+				}
+			}
 		}
 	}
-
 	// Update the state with pending changes
 	usedGas.Add(usedGas, gas)
 	receipt := types.NewReceipt(statedb.IntermediateRoot().Bytes(), usedGas)
-- 
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