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, 13 deletions

diff --git a/node/config.go b/node/config.go
index 99f325840..ff0725aab 100644
--- a/node/config.go
+++ b/node/config.go
@@ -27,6 +27,7 @@ import (
 	"sync"
 
 	"github.com/ethereum/go-ethereum/accounts"
+	"github.com/ethereum/go-ethereum/accounts/external"
 	"github.com/ethereum/go-ethereum/accounts/keystore"
 	"github.com/ethereum/go-ethereum/accounts/usbwallet"
 	"github.com/ethereum/go-ethereum/common"
@@ -80,6 +81,9 @@ type Config struct {
 	// is created by New and destroyed when the node is stopped.
 	KeyStoreDir string `toml:",omitempty"`
 
+	// ExternalSigner specifies an external URI for a clef-type signer
+	ExternalSigner string `toml:"omitempty"`
+
 	// UseLightweightKDF lowers the memory and CPU requirements of the key store
 	// scrypt KDF at the expense of security.
 	UseLightweightKDF bool `toml:",omitempty"`
@@ -462,23 +466,37 @@ func makeAccountManager(conf *Config) (*accounts.Manager, string, error) {
 		return nil, "", err
 	}
 	// Assemble the account manager and supported backends
-	backends := []accounts.Backend{
-		keystore.NewKeyStore(keydir, scryptN, scryptP),
-	}
-	if !conf.NoUSB {
-		// Start a USB hub for Ledger hardware wallets
-		if ledgerhub, err := usbwallet.NewLedgerHub(); err != nil {
-			log.Warn(fmt.Sprintf("Failed to start Ledger hub, disabling: %v", err))
+	backends := []accounts.Backend{}
+	if len(conf.ExternalSigner) > 0 {
+		log.Info("Using external signer", "url", conf.ExternalSigner)
+		if extapi, err := external.NewExternalBackend(conf.ExternalSigner); err == nil {
+			backends = append(backends, extapi)
 		} else {
-			backends = append(backends, ledgerhub)
+			log.Info("Error configuring external signer", "error", err)
 		}
-		// Start a USB hub for Trezor hardware wallets
-		if trezorhub, err := usbwallet.NewTrezorHub(); err != nil {
-			log.Warn(fmt.Sprintf("Failed to start Trezor hub, disabling: %v", err))
-		} else {
-			backends = append(backends, trezorhub)
+	}
+	if len(backends) == 0 {
+		// For now, we're using EITHER external signer OR local signers.
+		// If/when we implement some form of lockfile for USB and keystore wallets,
+		// we can have both, but it's very confusing for the user to see the same
+		// accounts in both externally and locally, plus very racey.
+		backends = append(backends, keystore.NewKeyStore(keydir, scryptN, scryptP))
+		if !conf.NoUSB {
+			// Start a USB hub for Ledger hardware wallets
+			if ledgerhub, err := usbwallet.NewLedgerHub(); err != nil {
+				log.Warn(fmt.Sprintf("Failed to start Ledger hub, disabling: %v", err))
+			} else {
+				backends = append(backends, ledgerhub)
+			}
+			// Start a USB hub for Trezor hardware wallets
+			if trezorhub, err := usbwallet.NewTrezorHub(); err != nil {
+				log.Warn(fmt.Sprintf("Failed to start Trezor hub, disabling: %v", err))
+			} else {
+				backends = append(backends, trezorhub)
+			}
 		}
 	}
+
 	return accounts.NewManager(backends...), ephemeral, nil
 }