Merge pull request #18028 from ryanschneider/blockhash-whitelist

cmd, eth: add support for `--whitelist <blocknum>=<hash>`

1 files changed, 19 insertions, 2 deletions

diff --git a/eth/handler.go b/eth/handler.go
index 741fc9d5a..b42612a56 100644
--- a/eth/handler.go
+++ b/eth/handler.go
@@ -88,6 +88,8 @@ type ProtocolManager struct {
 	txsSub        event.Subscription
 	minedBlockSub *event.TypeMuxSubscription
 
+	whitelist map[uint64]common.Hash
+
 	// channels for fetcher, syncer, txsyncLoop
 	newPeerCh   chan *peer
 	txsyncCh    chan *txsync
@@ -101,7 +103,7 @@ type ProtocolManager struct {
 
 // NewProtocolManager returns a new Ethereum sub protocol manager. The Ethereum sub protocol manages peers capable
 // with the Ethereum network.
-func NewProtocolManager(config *params.ChainConfig, mode downloader.SyncMode, networkID uint64, mux *event.TypeMux, txpool txPool, engine consensus.Engine, blockchain *core.BlockChain, chaindb ethdb.Database) (*ProtocolManager, error) {
+func NewProtocolManager(config *params.ChainConfig, mode downloader.SyncMode, networkID uint64, mux *event.TypeMux, txpool txPool, engine consensus.Engine, blockchain *core.BlockChain, chaindb ethdb.Database, whitelist map[uint64]common.Hash) (*ProtocolManager, error) {
 	// Create the protocol manager with the base fields
 	manager := &ProtocolManager{
 		networkID:   networkID,
@@ -110,6 +112,7 @@ func NewProtocolManager(config *params.ChainConfig, mode downloader.SyncMode, ne
 		blockchain:  blockchain,
 		chainconfig: config,
 		peers:       newPeerSet(),
+		whitelist:   whitelist,
 		newPeerCh:   make(chan *peer),
 		noMorePeers: make(chan struct{}),
 		txsyncCh:    make(chan *txsync),
@@ -307,7 +310,13 @@ func (pm *ProtocolManager) handle(p *peer) error {
 			}
 		}()
 	}
-	// main loop. handle incoming messages.
+	// If we have any explicit whitelist block hashes, request them
+	for number := range pm.whitelist {
+		if err := p.RequestHeadersByNumber(number, 1, 0, false); err != nil {
+			return err
+		}
+	}
+	// Handle incoming messages until the connection is torn down
 	for {
 		if err := pm.handleMsg(p); err != nil {
 			p.Log().Debug("Ethereum message handling failed", "err", err)
@@ -466,6 +475,14 @@ func (pm *ProtocolManager) handleMsg(p *peer) error {
 				p.Log().Debug("Verified to be on the same side of the DAO fork")
 				return nil
 			}
+			// Otherwise if it's a whitelisted block, validate against the set
+			if want, ok := pm.whitelist[headers[0].Number.Uint64()]; ok {
+				if hash := headers[0].Hash(); want != hash {
+					p.Log().Info("Whitelist mismatch, dropping peer", "number", headers[0].Number.Uint64(), "hash", hash, "want", want)
+					return errors.New("whitelist block mismatch")
+				}
+				p.Log().Debug("Whitelist block verified", "number", headers[0].Number.Uint64(), "hash", want)
+			}
 			// Irrelevant of the fork checks, send the header to the fetcher just in case
 			headers = pm.fetcher.FilterHeaders(p.id, headers, time.Now())
 		}