fix: re-encode calldata in mutator and refactor (#380)

* fix: re-encode calldata in mutator and refactor

* panic on misuse

fuzzing/calls/call_message.go

@@ -1,14 +1,15 @@
 package calls
 
 import (
+	"math/big"
+
 	"github.com/crytic/medusa/chain"
 	"github.com/crytic/medusa/logging"
 	"github.com/ethereum/go-ethereum/common"
 	"github.com/ethereum/go-ethereum/common/hexutil"
 	"github.com/ethereum/go-ethereum/core"
 	coreTypes "github.com/ethereum/go-ethereum/core/types"
 	"golang.org/x/exp/slices"
-	"math/big"
 )
 
 // The following directives will be picked up by the `go generate` command to generate JSON marshaling code from
@@ -126,6 +127,25 @@ func NewCallMessageWithAbiValueData(from common.Address, to *common.Address, non
 	}
 }
 
+// WithDataAbiValues resets the call message's data and ABI values, ensuring the values are in sync and
+// reusing the other existing fields.
+func (m *CallMessage) WithDataAbiValues(abiData *CallMessageDataAbiValues) {
+	if abiData == nil {
+		logging.GlobalLogger.Panic("Method ABI and data should always be defined")
+	}
+
+	// Pack the ABI value data
+	var data []byte
+	var err error
+	data, err = abiData.Pack()
+	if err != nil {
+		logging.GlobalLogger.Panic("Failed to pack call message ABI values", err)
+	}
+	// Set our data and ABI values
+	m.DataAbiValues = abiData
+	m.Data = data
+}
+
 // FillFromTestChainProperties populates gas limit, price, nonce, and other fields automatically based on the worker's
 // underlying test chain properties if they are not yet set.
 func (m *CallMessage) FillFromTestChainProperties(chain *chain.TestChain) {

fuzzing/fuzzer_worker.go

@@ -10,7 +10,6 @@ import (
 	fuzzerTypes "github.com/crytic/medusa/fuzzing/contracts"
 	"github.com/crytic/medusa/fuzzing/coverage"
 	"github.com/crytic/medusa/fuzzing/valuegeneration"
-	"github.com/crytic/medusa/logging"
 	"github.com/crytic/medusa/utils"
 	"github.com/crytic/medusa/utils/randomutils"
 	"github.com/ethereum/go-ethereum/common"
@@ -482,12 +481,8 @@ func (fw *FuzzerWorker) shrinkCallSequence(callSequence calls.CallSequence, shri
 					abiValuesMsgData.InputValues[j] = mutatedInput
 				}
 
-				// Re-encode the ABI values as calldata.
-				abiData, err := abiValuesMsgData.Pack()
-				if err != nil {
-					logging.GlobalLogger.Panic("Failed to pack call message ABI values", err)
-				}
-				possibleShrunkSequence[i].Call.Data = abiData
+				// Re-encode the message's calldata
+				possibleShrunkSequence[i].Call.WithDataAbiValues(abiValuesMsgData)
 
 				// Test the shrunken sequence.
 				validShrunkSequence, err := fw.testShrunkenCallSequence(possibleShrunkSequence, shrinkRequest)

fuzzing/fuzzer_worker_sequence_generator.go

@@ -460,5 +460,8 @@ func prefetchModifyCallFuncMutate(sequenceGenerator *CallSequenceGenerator, elem
 		}
 		abiValuesMsgData.InputValues[i] = mutatedInput
 	}
+	// Re-encode the message's calldata
+	element.Call.WithDataAbiValues(abiValuesMsgData)
+
 	return nil
 }