accounts, eth, clique, signer: support for external signer API (#18079)

* accounts, eth, clique: implement external backend + move sighash calc to backend

* signer: implement account_Version on external API

* accounts/external: enable ipc, add copyright

* accounts, internal, signer: formatting

* node: go fmt

* flags: disallow --dev in combo with --externalsigner

* accounts: remove clique-specific signing method, replace with more generic

* accounts, consensus: formatting + fix error in tests

* signer/core: remove (test-) import cycle

* clique: remove unused import

* accounts: remove CliqueHash and avoid dependency on package crypto

* consensus/clique: unduplicate header encoding

1 files changed, 31 insertions, 4 deletions

diff --git a/accounts/accounts.go b/accounts/accounts.go
index cb1eae281..11232b19a 100644
--- a/accounts/accounts.go
+++ b/accounts/accounts.go
@@ -18,12 +18,14 @@
 package accounts
 
 import (
+	"fmt"
 	"math/big"
 
 	ethereum "github.com/ethereum/go-ethereum"
 	"github.com/ethereum/go-ethereum/common"
 	"github.com/ethereum/go-ethereum/core/types"
 	"github.com/ethereum/go-ethereum/event"
+	"golang.org/x/crypto/sha3"
 )
 
 // Account represents an Ethereum account located at a specific location defined
@@ -87,8 +89,20 @@ type Wallet interface {
 	// chain state reader.
 	SelfDerive(base DerivationPath, chain ethereum.ChainStateReader)
 
-	// SignHash requests the wallet to sign the given hash.
+	// SignData requests the wallet to sign the hash of the given data
+	// It looks up the account specified either solely via its address contained within,
+	// or optionally with the aid of any location metadata from the embedded URL field.
 	//
+	// If the wallet requires additional authentication to sign the request (e.g.
+	// a password to decrypt the account, or a PIN code o verify the transaction),
+	// an AuthNeededError instance will be returned, containing infos for the user
+	// about which fields or actions are needed. The user may retry by providing
+	// the needed details via SignHashWithPassphrase, or by other means (e.g. unlock
+	// the account in a keystore).
+	SignData(account Account, mimeType string, data []byte) ([]byte, error)
+
+	// Signtext requests the wallet to sign the hash of a given piece of data, prefixed
+	// by the Ethereum prefix scheme
 	// It looks up the account specified either solely via its address contained within,
 	// or optionally with the aid of any location metadata from the embedded URL field.
 	//
@@ -98,7 +112,7 @@ type Wallet interface {
 	// about which fields or actions are needed. The user may retry by providing
 	// the needed details via SignHashWithPassphrase, or by other means (e.g. unlock
 	// the account in a keystore).
-	SignHash(account Account, hash []byte) ([]byte, error)
+	SignText(account Account, text []byte) ([]byte, error)
 
 	// SignTx requests the wallet to sign the given transaction.
 	//
@@ -113,12 +127,12 @@ type Wallet interface {
 	// the account in a keystore).
 	SignTx(account Account, tx *types.Transaction, chainID *big.Int) (*types.Transaction, error)
 
-	// SignHashWithPassphrase requests the wallet to sign the given hash with the
+	// SignTextWithPassphrase requests the wallet to sign the given text with the
 	// given passphrase as extra authentication information.
 	//
 	// It looks up the account specified either solely via its address contained within,
 	// or optionally with the aid of any location metadata from the embedded URL field.
-	SignHashWithPassphrase(account Account, passphrase string, hash []byte) ([]byte, error)
+	SignTextWithPassphrase(account Account, passphrase string, hash []byte) ([]byte, error)
 
 	// SignTxWithPassphrase requests the wallet to sign the given transaction, with the
 	// given passphrase as extra authentication information.
@@ -148,6 +162,19 @@ type Backend interface {
 	Subscribe(sink chan<- WalletEvent) event.Subscription
 }
 
+// TextHash is a helper function that calculates a hash for the given message that can be
+// safely used to calculate a signature from.
+//
+// The hash is calulcated as
+//   keccak256("\x19Ethereum Signed Message:\n"${message length}${message}).
+//
+// This gives context to the signed message and prevents signing of transactions.
+func TextHash(data []byte) []byte {
+	hash := sha3.NewLegacyKeccak256()
+	fmt.Fprintf(hash, "\x19Ethereum Signed Message:\n%d%s", len(data), data)
+	return hash.Sum(nil)
+}
+
 // WalletEventType represents the different event types that can be fired by
 // the wallet subscription subsystem.
 type WalletEventType int