From 656dd986267eb37551f1b231aa5b7f5e2850a868 Mon Sep 17 00:00:00 2001
From: Peter Broadhurst <peter.broadhurst@kaleido.io>
Date: Sun, 27 Oct 2024 15:22:06 -0400
Subject: [PATCH] Allow round-tripping of unsigned EIP-1559 signature payloads

Signed-off-by: Peter Broadhurst <peter.broadhurst@kaleido.io>
---
 pkg/ethsigner/transaction.go      | 25 ++++++++++++++++-------
 pkg/ethsigner/transaction_test.go | 33 ++++++++++++++++++++++++++++++-
 2 files changed, 50 insertions(+), 8 deletions(-)

diff --git a/pkg/ethsigner/transaction.go b/pkg/ethsigner/transaction.go
index 22ea6a0a..26a2bb6b 100644
--- a/pkg/ethsigner/transaction.go
+++ b/pkg/ethsigner/transaction.go
@@ -299,8 +299,7 @@ func recoverCommon(tx *Transaction, message []byte, chainID int64, v int64, r, s
 	}, nil
 }
 
-func RecoverEIP1559Transaction(ctx context.Context, rawTx ethtypes.HexBytes0xPrefix, chainID int64) (*ethtypes.Address0xHex, *TransactionWithOriginalPayload, error) {
-
+func decodeEIP1559SignaturePayload(ctx context.Context, rawTx ethtypes.HexBytes0xPrefix, chainID int64, rlpMinLen int) (rlp.List, *Transaction, error) {
 	if len(rawTx) == 0 || rawTx[0] != TransactionType1559 {
 		return nil, nil, i18n.NewError(ctx, signermsgs.MsgInvalidEIP1559Transaction, "TransactionType")
 	}
@@ -311,18 +310,17 @@ func RecoverEIP1559Transaction(ctx context.Context, rawTx ethtypes.HexBytes0xPre
 		log.L(ctx).Errorf("Invalid EIP-1559 transaction data '%s': %s", rawTx, err)
 		return nil, nil, i18n.NewError(ctx, signermsgs.MsgInvalidEIP1559Transaction, err)
 	}
+	rlpList := decoded.(rlp.List)
 
-	if decoded == nil || len(decoded.(rlp.List)) < 12 {
-		log.L(ctx).Errorf("Invalid EIP-1559 transaction data '%s': EOF", rawTx)
+	if len(rlpList) < rlpMinLen {
+		log.L(ctx).Errorf("Invalid EIP-1559 transaction data (%d RLP elements)", rlpList)
 		return nil, nil, i18n.NewError(ctx, signermsgs.MsgInvalidEIP1559Transaction, "EOF")
 	}
-	rlpList := decoded.(rlp.List)
-
 	encodedChainID := rlpList[0].ToData().IntOrZero().Int64()
 	if encodedChainID != chainID {
 		return nil, nil, i18n.NewError(ctx, signermsgs.MsgInvalidChainID, chainID, encodedChainID)
 	}
-	tx := &Transaction{
+	return rlpList, &Transaction{
 		Nonce:                (*ethtypes.HexInteger)(rlpList[1].ToData().Int()),
 		MaxPriorityFeePerGas: (*ethtypes.HexInteger)(rlpList[2].ToData().Int()),
 		MaxFeePerGas:         (*ethtypes.HexInteger)(rlpList[3].ToData().Int()),
@@ -331,6 +329,19 @@ func RecoverEIP1559Transaction(ctx context.Context, rawTx ethtypes.HexBytes0xPre
 		Value:                (*ethtypes.HexInteger)(rlpList[6].ToData().Int()),
 		Data:                 ethtypes.HexBytes0xPrefix(rlpList[7].ToData()),
 		// No access list support
+	}, nil
+}
+
+func DecodeEIP1559SignaturePayload(ctx context.Context, rawTx ethtypes.HexBytes0xPrefix, chainID int64) (*Transaction, error) {
+	_, tx, err := decodeEIP1559SignaturePayload(ctx, rawTx, chainID, 9 /* no signature data */)
+	return tx, err
+}
+
+func RecoverEIP1559Transaction(ctx context.Context, rawTx ethtypes.HexBytes0xPrefix, chainID int64) (*ethtypes.Address0xHex, *TransactionWithOriginalPayload, error) {
+
+	rlpList, tx, err := decodeEIP1559SignaturePayload(ctx, rawTx, chainID, 12 /* with signature data */)
+	if err != nil {
+		return nil, nil, err
 	}
 
 	return recoverCommon(tx,
diff --git a/pkg/ethsigner/transaction_test.go b/pkg/ethsigner/transaction_test.go
index d34bd4e5..ee0020a9 100644
--- a/pkg/ethsigner/transaction_test.go
+++ b/pkg/ethsigner/transaction_test.go
@@ -1,4 +1,4 @@
-// Copyright © 2022 Kaleido, Inc.
+// Copyright © 2024 Kaleido, Inc.
 //
 // SPDX-License-Identifier: Apache-2.0
 //
@@ -31,6 +31,7 @@ import (
 	"github.com/hyperledger/firefly-signer/pkg/secp256k1"
 	"github.com/stretchr/testify/assert"
 	"github.com/stretchr/testify/mock"
+	"github.com/stretchr/testify/require"
 )
 
 func TestEncodeExistingLegacyEIP155(t *testing.T) {
@@ -294,6 +295,36 @@ func TestRecoverEIP1559BadStructure(t *testing.T) {
 	assert.Regexp(t, "FF22084.*EOF", err)
 }
 
+func TestDecodeEIP1559SignaturePayloadEmpty(t *testing.T) {
+	_, err := DecodeEIP1559SignaturePayload(context.Background(), []byte{}, 1001)
+	assert.Regexp(t, "FF22084.*TransactionType", err)
+}
+
+func TestRoundTripEIP1559Payload(t *testing.T) {
+
+	txIn := Transaction{
+		Nonce:                ethtypes.NewHexInteger64(3),
+		GasLimit:             ethtypes.NewHexInteger64(40574),
+		MaxPriorityFeePerGas: ethtypes.NewHexInteger64(505050),
+		MaxFeePerGas:         ethtypes.NewHexInteger64(606060),
+		To:                   ethtypes.MustNewAddress("0x497eedc4299dea2f2a364be10025d0ad0f702de3"),
+		Data:                 ethtypes.MustNewHexBytes0xPrefix("0xfeedbeef"),
+		Value:                ethtypes.NewHexInteger64(100000000),
+	}
+	abiData := txIn.SignaturePayloadEIP1559(1001).Bytes()
+
+	txOut, err := DecodeEIP1559SignaturePayload(context.Background(), abiData, 1001)
+	require.NoError(t, err)
+
+	jsonIn, err := json.Marshal(txIn)
+	require.NoError(t, err)
+	jsonOut, err := json.Marshal(txOut)
+	require.NoError(t, err)
+
+	require.JSONEq(t, string(jsonIn), string(jsonOut))
+
+}
+
 func TestRecoverEIP1559BadChainID(t *testing.T) {
 	_, _, err := RecoverEIP1559Transaction(context.Background(), append([]byte{TransactionType1559}, (rlp.List{
 		rlp.WrapInt(big.NewInt(111)),