eth/protocols/snap: use trie to serve trie healing requests if snapshot is unavailable

Author: holiman

eth/protocols/snap/handler.go

@@ -23,12 +23,14 @@ import (
 
 	"github.com/ethereum/go-ethereum/common"
 	"github.com/ethereum/go-ethereum/core"
+	"github.com/ethereum/go-ethereum/core/types"
 	"github.com/ethereum/go-ethereum/light"
 	"github.com/ethereum/go-ethereum/log"
 	"github.com/ethereum/go-ethereum/metrics"
 	"github.com/ethereum/go-ethereum/p2p"
 	"github.com/ethereum/go-ethereum/p2p/enode"
 	"github.com/ethereum/go-ethereum/p2p/enr"
+	"github.com/ethereum/go-ethereum/rlp"
 	"github.com/ethereum/go-ethereum/trie"
 )
 
@@ -518,17 +520,30 @@ func ServiceGetTrieNodesQuery(chain *core.BlockChain, req *GetTrieNodesPacket, s
 			bytes += uint64(len(blob))
 
 		default:
+			var stRoot common.Hash
 			// Storage slots requested, open the storage trie and retrieve from there
 			if snap == nil {
-				// We don't have the requested state snapshotted yet (or it is stale), bail out.
-				break
-			}
-			account, err := snap.Account(common.BytesToHash(pathset[0]))
-			loads++ // always account database reads, even for failures
-			if err != nil || account == nil {
-				break
+				var account types.StateAccount
+				// We don't have the requested state snapshotted yet (or it is stale).
+				// We can look  up the account from the account trie instead.
+				blob, resolved, err := accTrie.TryGetNode(pathset[0])
+				loads += resolved // always account database reads, even for failures
+				if err != nil {
+					break
+				}
+				if err = rlp.DecodeBytes(blob, &account); err != nil {
+					break
+				}
+				stRoot = account.Root
+			} else {
+				account, err := snap.Account(common.BytesToHash(pathset[0]))
+				loads++ // always account database reads, even for failures
+				if err != nil || account == nil {
+					break
+				}
+				stRoot = common.BytesToHash(account.Root)
 			}
-			id := trie.StorageTrieID(req.Root, common.BytesToHash(pathset[0]), common.BytesToHash(account.Root))
+			id := trie.StorageTrieID(req.Root, common.BytesToHash(pathset[0]), stRoot)
 			stTrie, err := trie.NewStateTrie(id, triedb)
 			loads++ // always account database reads, even for failures
 			if err != nil {