Merge pull request #141 from zacshowa/update-validator

Refactor and expand validator preconditions to espresso STF logic

cmd/replay/espresso_validation.go

@@ -0,0 +1,46 @@
+package main
+
+import (
+	"fmt"
+	"github.com/offchainlabs/nitro/arbos"
+	"github.com/offchainlabs/nitro/arbos/arbostypes"
+	"github.com/offchainlabs/nitro/wavmio"
+)
+
+// / Handle Espresso Pre Conditions
+// /
+// / Description: This function takes in the most recently received message (of type arbostypes.MessageWithMetadata),
+// /	 			  and a boolean from the ChainConfig
+// / 			 and uses the parameters to perform all checks gating the modified STF logic in the arbitrum validator.
+// /
+// / Return: A boolean representing the result of a logical and of all checks (that don't result in panics) gating espressos STF logic.
+// /
+// / Panics: This function will panic if the message type is not an espresso message, but the HotShot height is non-zero
+// / 		as this is an invalid state for the STF to reside in.
+// /
+func handleEspressoPreConditions(message *arbostypes.MessageWithMetadata, isEnabled bool) (bool, func()) {
+	// calculate and cache all values needed to determine if the preconditions are met to enter the Espresso STF logic
+	isNonEspressoMessage := arbos.IsL2NonEspressoMsg(message.Message)
+	hotshotHeight := wavmio.GetEspressoHeight()
+
+	validatingEspressoLivenessFailure := isNonEspressoMessage && isEnabled
+	validatingEspressoHeightFailure := isNonEspressoMessage && hotshotHeight != 0
+	validatingAgainstEspresso := arbos.IsEspressoMsg(message.Message) && isEnabled
+
+	if validatingEspressoLivenessFailure {
+		// previously this was the only other branch that was checked when `validatingAgainstEspresso`
+		return validatingAgainstEspresso, func() {
+			l1Block := message.Message.Header.BlockNumber
+			if wavmio.IsHotShotLive(l1Block) {
+				panic(fmt.Sprintf("getting the centralized message while hotshot is good, l1Height: %v", l1Block))
+			}
+		}
+	} else if validatingEspressoHeightFailure {
+		// If conditions are such that we have been working in espresso mode, but we are suddenly receiving non espresso messages,
+		// something incorrect has occurred and we must panic
+		return validatingAgainstEspresso, func() {
+			panic("The messaged received by the STF is not an Espresso message, but the validator is running in Espresso mode")
+		}
+	}
+	return validatingAgainstEspresso, nil // return nil for the panic handler such that it is a no-op in the caller if no errors need occur.
+}

cmd/replay/main.go

@@ -279,8 +279,8 @@ func main() {
 			return wavmio.ReadInboxMessage(batchNum), nil
 		}
 
-		validatingAgainstEspresso := arbos.IsEspressoMsg(message.Message) && chainConfig.ArbitrumChainParams.EnableEspresso
-		validatingEspressoLivenessFailure := arbos.IsL2NonEspressoMsg(message.Message) && chainConfig.ArbitrumChainParams.EnableEspresso
+		// Handle the various pre-conditions and panics that can happen before we should enter the espresso logic in the validators STF
+		validatingAgainstEspresso, panicHandler := handleEspressoPreConditions(message, chainConfig.ArbitrumChainParams.EnableEspresso)
 		if validatingAgainstEspresso {
 			txs, jst, err := arbos.ParseEspressoMsg(message.Message)
 			if err != nil {
@@ -325,11 +325,9 @@ func main() {
 				espressocrypto.VerifyNamespace(chainConfig.ChainID.Uint64(), *jst.Proof, *jst.Header.PayloadCommitment, *jst.Header.NsTable, txs, *jst.VidCommon)
 			}
 
-		} else if validatingEspressoLivenessFailure {
-			l1Block := message.Message.Header.BlockNumber
-			if wavmio.IsHotShotLive(l1Block) {
-				panic(fmt.Sprintf("getting the centralized message while hotshot is good, l1Height: %v", l1Block))
-			}
+		} else if panicHandler != nil {
+			// Call the error case closure returned by handleEspressoPreconditions() if it isn't nil
+			panicHandler()
 		}
 
 		newBlock, _, err = arbos.ProduceBlock(message.Message, message.DelayedMessagesRead, lastBlockHeader, statedb, chainContext, chainConfig, batchFetcher, false)