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

4 files changed, 35 insertions, 22 deletions

diff --git a/cmd/clef/main.go b/cmd/clef/main.go
index 519d63b3c..e2b85288d 100644
--- a/cmd/clef/main.go
+++ b/cmd/clef/main.go
@@ -49,12 +49,6 @@ import (
 	"gopkg.in/urfave/cli.v1"
 )
 
-// ExternalAPIVersion -- see extapi_changelog.md
-const ExternalAPIVersion = "4.0.0"
-
-// InternalAPIVersion -- see intapi_changelog.md
-const InternalAPIVersion = "3.0.0"
-
 const legalWarning = `
 WARNING! 
 
@@ -479,8 +473,8 @@ func signer(c *cli.Context) error {
 	}
 	ui.OnSignerStartup(core.StartupInfo{
 		Info: map[string]interface{}{
-			"extapi_version": ExternalAPIVersion,
-			"intapi_version": InternalAPIVersion,
+			"extapi_version": core.ExternalAPIVersion,
+			"intapi_version": core.InternalAPIVersion,
 			"extapi_http":    extapiURL,
 			"extapi_ipc":     ipcapiURL,
 		},
diff --git a/cmd/geth/main.go b/cmd/geth/main.go
index 0a6616312..dca02c82e 100644
--- a/cmd/geth/main.go
+++ b/cmd/geth/main.go
@@ -62,6 +62,7 @@ var (
 		utils.BootnodesV5Flag,
 		utils.DataDirFlag,
 		utils.KeyStoreDirFlag,
+		utils.ExternalSignerFlag,
 		utils.NoUSBFlag,
 		utils.DashboardEnabledFlag,
 		utils.DashboardAddrFlag,
@@ -293,13 +294,14 @@ func startNode(ctx *cli.Context, stack *node.Node) {
 	utils.StartNode(stack)
 
 	// Unlock any account specifically requested
-	ks := stack.AccountManager().Backends(keystore.KeyStoreType)[0].(*keystore.KeyStore)
-
-	passwords := utils.MakePasswordList(ctx)
-	unlocks := strings.Split(ctx.GlobalString(utils.UnlockedAccountFlag.Name), ",")
-	for i, account := range unlocks {
-		if trimmed := strings.TrimSpace(account); trimmed != "" {
-			unlockAccount(ctx, ks, trimmed, i, passwords)
+	if keystores := stack.AccountManager().Backends(keystore.KeyStoreType); len(keystores) > 0 {
+		ks := keystores[0].(*keystore.KeyStore)
+		passwords := utils.MakePasswordList(ctx)
+		unlocks := strings.Split(ctx.GlobalString(utils.UnlockedAccountFlag.Name), ",")
+		for i, account := range unlocks {
+			if trimmed := strings.TrimSpace(account); trimmed != "" {
+				unlockAccount(ctx, ks, trimmed, i, passwords)
+			}
 		}
 	}
 	// Register wallet event handlers to open and auto-derive wallets
diff --git a/cmd/geth/usage.go b/cmd/geth/usage.go
index 1579134f9..0b5c6fd90 100644
--- a/cmd/geth/usage.go
+++ b/cmd/geth/usage.go
@@ -145,6 +145,7 @@ var AppHelpFlagGroups = []flagGroup{
 		Flags: []cli.Flag{
 			utils.UnlockedAccountFlag,
 			utils.PasswordFileFlag,
+			utils.ExternalSignerFlag,
 		},
 	},
 	{
diff --git a/cmd/utils/flags.go b/cmd/utils/flags.go
index a3602182a..bf20abe81 100644
--- a/cmd/utils/flags.go
+++ b/cmd/utils/flags.go
@@ -427,7 +427,11 @@ var (
 		Usage: "Password file to use for non-interactive password input",
 		Value: "",
 	}
-
+	ExternalSignerFlag = cli.StringFlag{
+		Name:  "signer",
+		Usage: "External signer (url or path to ipc file)",
+		Value: "",
+	}
 	VMEnableDebugFlag = cli.BoolFlag{
 		Name:  "vmdebug",
 		Usage: "Record information useful for VM and contract debugging",
@@ -990,11 +994,15 @@ func setEtherbase(ctx *cli.Context, ks *keystore.KeyStore, cfg *eth.Config) {
 	}
 	// Convert the etherbase into an address and configure it
 	if etherbase != "" {
-		account, err := MakeAddress(ks, etherbase)
-		if err != nil {
-			Fatalf("Invalid miner etherbase: %v", err)
+		if ks != nil {
+			account, err := MakeAddress(ks, etherbase)
+			if err != nil {
+				Fatalf("Invalid miner etherbase: %v", err)
+			}
+			cfg.Etherbase = account.Address
+		} else {
+			Fatalf("No etherbase configured")
 		}
-		cfg.Etherbase = account.Address
 	}
 }
 
@@ -1093,6 +1101,10 @@ func SetNodeConfig(ctx *cli.Context, cfg *node.Config) {
 	setNodeUserIdent(ctx, cfg)
 	setDataDir(ctx, cfg)
 
+	if ctx.GlobalIsSet(ExternalSignerFlag.Name) {
+		cfg.ExternalSigner = ctx.GlobalString(ExternalSignerFlag.Name)
+	}
+
 	if ctx.GlobalIsSet(KeyStoreDirFlag.Name) {
 		cfg.KeyStoreDir = ctx.GlobalString(KeyStoreDirFlag.Name)
 	}
@@ -1274,8 +1286,12 @@ func SetEthConfig(ctx *cli.Context, stack *node.Node, cfg *eth.Config) {
 	// Avoid conflicting network flags
 	checkExclusive(ctx, DeveloperFlag, TestnetFlag, RinkebyFlag, GoerliFlag)
 	checkExclusive(ctx, LightServFlag, SyncModeFlag, "light")
-
-	ks := stack.AccountManager().Backends(keystore.KeyStoreType)[0].(*keystore.KeyStore)
+	// Can't use both ephemeral unlocked and external signer
+	checkExclusive(ctx, DeveloperFlag, ExternalSignerFlag)
+	var ks *keystore.KeyStore
+	if keystores := stack.AccountManager().Backends(keystore.KeyStoreType); len(keystores) > 0 {
+		ks = keystores[0].(*keystore.KeyStore)
+	}
 	setEtherbase(ctx, ks, cfg)
 	setGPO(ctx, &cfg.GPO)
 	setTxPool(ctx, &cfg.TxPool)