signer,clef: implement timeout for external api

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! 
 
@@ -110,6 +104,11 @@ var (
 		Usage: "File used to emit audit logs. Set to \"\" to disable",
 		Value: "audit.log",
 	}
+	timeoutFlag = cli.DurationFlag{
+		Name:  "timeout",
+		Usage: "Specify a timeout, so external callers get a response within a certain time (default 0 = no timeout)",
+		Value: 0,
+	}
 	ruleFlag = cli.StringFlag{
 		Name:  "rules",
 		Usage: "Enable rule-engine",
@@ -194,6 +193,7 @@ func init() {
 		dBFlag,
 		customDBFlag,
 		auditLogFlag,
+		timeoutFlag,
 		ruleFlag,
 		stdiouiFlag,
 		testFlag,
@@ -414,6 +414,12 @@ func signer(c *cli.Context) error {
 		c.GlobalBool(utils.LightKDFFlag.Name),
 		c.GlobalBool(advancedMode.Name))
 	api = apiImpl
+
+	// Timeout
+	if timeout := c.GlobalDuration(timeoutFlag.Name); timeout > 0 {
+		log.Info("extapi timeout set", "time", timeout)
+		api = core.NewTimedExternalAPI(api, timeout)
+	}
 	// Audit logging
 	if logfile := c.GlobalString(auditLogFlag.Name); logfile != "" {
 		api, err = core.NewAuditLogger(logfile, api)
@@ -479,8 +485,8 @@ func signer(c *cli.Context) error {
 	}
 	ui.OnSignerStartup(core.StartupInfo{
 		Info: map[string]interface{}{
-			"extapi_version": ExternalAPIVersion,
+			"extapi_version": core.ExternalAPIVersion,
-			"intapi_version": InternalAPIVersion,
+			"intapi_version": core.InternalAPIVersion,
 			"extapi_http":    extapiURL,
 			"extapi_ipc":     ipcapiURL,
 		},

signer/core/api.go

@@ -36,8 +36,14 @@ import (
 	"github.com/ethereum/go-ethereum/rlp"
 )
 
-// numberOfAccountsToDerive For hardware wallets, the number of accounts to derive
+const(
-const numberOfAccountsToDerive = 10
+	// numberOfAccountsToDerive For hardware wallets, the number of accounts to derive
+	numberOfAccountsToDerive = 10
+	// ExternalAPIVersion -- see extapi_changelog.md
+	ExternalAPIVersion = "4.0.0"
+	// InternalAPIVersion -- see intapi_changelog.md
+	InternalAPIVersion = "3.0.0"
+)
 
 // ExternalAPI defines the external API through which signing requests are made.
 type ExternalAPI interface {

signer/core/timeout.go

@@ -0,0 +1,135 @@
+package core
+
+import (
+	"context"
+	"encoding/json"
+	"fmt"
+	"github.com/ethereum/go-ethereum/accounts"
+	"github.com/ethereum/go-ethereum/common"
+	"github.com/ethereum/go-ethereum/common/hexutil"
+	"github.com/ethereum/go-ethereum/internal/ethapi"
+	"github.com/ethereum/go-ethereum/log"
+	"time"
+)
+
+// The TimedExternalAPI implements ExternalAPI, but can be configured to time out after a specified interval.
+// This can be used to ensure that callers get a response within reasonable time,
+// even if the user is unresponsive.
+type TimedExternalAPI struct {
+	timeout time.Duration
+	next    ExternalAPI
+}
+
+func NewTimedExternalAPI(next ExternalAPI, timeout time.Duration) ExternalAPI {
+	return &TimedExternalAPI{timeout, next}
+}
+
+var (
+	ErrTimeout = fmt.Errorf("timeout occurred")
+)
+
+func (t *TimedExternalAPI) List(ctx context.Context) ([]common.Address, error) {
+	type response struct {
+		addr []common.Address
+		err  error
+	}
+	ch := make(chan response)
+	go func() {
+		addr, err := t.next.List(ctx)
+		ch <- response{addr, err}
+	}()
+
+	select {
+	case r := <-ch:
+		return r.addr, r.err
+	case <-time.After(t.timeout):
+		log.Info("timeout", "op", "list")
+		go func() { <-ch }()
+		return []common.Address{}, ErrTimeout
+	}
+}
+
+func (t *TimedExternalAPI) New(ctx context.Context) (accounts.Account, error) {
+	type response struct {
+		acc accounts.Account
+		err error
+	}
+	ch := make(chan response)
+	go func() {
+		acc, err := t.next.New(ctx)
+		ch <- response{acc, err}
+	}()
+
+	select {
+	case r := <-ch:
+		return r.acc, r.err
+	case <-time.After(t.timeout):
+		log.Info("timeout", "op", "list")
+		go func() { <-ch }()
+		return accounts.Account{}, ErrTimeout
+	}
+}
+
+func (t *TimedExternalAPI) SignTransaction(ctx context.Context, args SendTxArgs, methodSelector *string) (*ethapi.SignTransactionResult, error) {
+	type response struct {
+		res *ethapi.SignTransactionResult
+		err error
+	}
+	ch := make(chan response)
+	go func() {
+		res, err := t.next.SignTransaction(ctx, args, methodSelector)
+		ch <- response{res, err}
+	}()
+	select {
+	case r := <-ch:
+		return r.res, r.err
+	case <-time.After(t.timeout):
+		log.Info("timeout", "op", "signTransaction")
+		go func() { <-ch }()
+		return nil, ErrTimeout
+	}
+}
+
+func (t *TimedExternalAPI) Sign(ctx context.Context, addr common.MixedcaseAddress, data hexutil.Bytes) (hexutil.Bytes, error) {
+	type response struct {
+		res hexutil.Bytes
+		err error
+	}
+	ch := make(chan response)
+	go func() {
+		res, err := t.next.Sign(ctx, addr, data)
+		ch <- response{res, err}
+	}()
+	select {
+	case r := <-ch:
+		return r.res, r.err
+	case <-time.After(t.timeout):
+		log.Info("timeout", "op", "sign")
+		go func() { <-ch }()
+		return nil, ErrTimeout
+	}
+}
+
+func (t *TimedExternalAPI) Export(ctx context.Context, addr common.Address) (json.RawMessage, error) {
+	type response struct {
+		res json.RawMessage
+		err error
+	}
+	ch := make(chan response)
+	go func() {
+		res, err := t.next.Export(ctx, addr)
+		ch <- response{res, err}
+	}()
+	select {
+	case r := <-ch:
+		return r.res, r.err
+	case <-time.After(t.timeout):
+		log.Info("timeout", "op", "sign")
+		go func() { <-ch }()
+		return json.RawMessage{}, ErrTimeout
+	}
+}
+
+func (t *TimedExternalAPI) Version(ctx context.Context) (string, error) {
+	return ExternalAPIVersion, nil
+}