New API call for signatures.

rpc/api.go

@@ -158,6 +158,17 @@ func (api *EthereumApi) GetRequestReply(req *RpcRequest, reply *interface{}) err
 		v := api.xethAtStateNum(args.BlockNumber).CodeAtBytes(args.Address)
 		*reply = newHexData(v)
 
+	case "eth_sign":
+		args := new(NewSigArgs)
+		if err := json.Unmarshal(req.Params, &args); err != nil {
+			return err
+		}
+		v, err := api.xeth.Sign(args.From, args.Data)
+		if err != nil {
+			return err
+		}
+		*reply = v
+
 	case "eth_sendTransaction", "eth_transact":
 		args := new(NewTxArgs)
 		if err := json.Unmarshal(req.Params, &args); err != nil {

rpc/args.go

@@ -166,6 +166,11 @@ type NewTxArgs struct {
 	BlockNumber int64
 }
 
+type NewSigArgs struct {
+	From string
+	Data string
+}
+
 func (args *NewTxArgs) UnmarshalJSON(b []byte) (err error) {
 	var obj []json.RawMessage
 	var ext struct {

xeth/xeth.go

@@ -813,6 +813,27 @@ func (self *XEth) ConfirmTransaction(tx string) bool {
 	return self.frontend.ConfirmTransaction(tx)
 }
 
+func (self *XEth) Sign(fromStr, hashStr string) (string, error) {
+	var (
+		from = common.HexToAddress(fromStr)
+		hash = common.HexToHash(hashStr)
+	)
+	sig, err := self.backend.AccountManager().Sign(accounts.Account{Address: from.Bytes()}, hash)
+	if err == accounts.ErrLocked {
+		if didUnlock {
+			return fmt.Errorf("signer account still locked after successful unlock")
+		}
+		if !self.frontend.UnlockAccount(from.Bytes()) {
+			return fmt.Errorf("could not unlock signer account")
+		}
+		// retry signing, the account should now be unlocked.
+		return self.Sign(fromStr, hashStr)
+	} else if err != nil {
+		return err
+	}
+	return common.toHex(sig)
+}
+
 func (self *XEth) Transact(fromStr, toStr, nonceStr, valueStr, gasStr, gasPriceStr, codeStr string) (string, error) {
 
 	// this minimalistic recoding is enough (works for natspec.js)