support for user agents

rpc/useragent/remote_frontend.go

@@ -0,0 +1,141 @@
+// Copyright 2015 The go-ethereum Authors
+// This file is part of the go-ethereum library.
+//
+// The go-ethereum library is free software: you can redistribute it and/or modify
+// it under the terms of the GNU Lesser General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// The go-ethereum library is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+// GNU Lesser General Public License for more details.
+//
+// You should have received a copy of the GNU Lesser General Public License
+// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.
+
+package useragent
+
+import (
+	"encoding/json"
+	"fmt"
+	"net"
+
+	"github.com/ethereum/go-ethereum/accounts"
+	"github.com/ethereum/go-ethereum/common"
+	"github.com/ethereum/go-ethereum/logger"
+	"github.com/ethereum/go-ethereum/logger/glog"
+	"github.com/ethereum/go-ethereum/rpc/shared"
+)
+
+// remoteFrontend implements xeth.Frontend and will communicate with an external
+// user agent over a connection
+type RemoteFrontend struct {
+	enabled bool
+	mgr     *accounts.Manager
+	d       *json.Decoder
+	e       *json.Encoder
+	n       int
+}
+
+// NewRemoteFrontend creates a new frontend which will interact with an user agent
+// over the given connection
+func NewRemoteFrontend(conn net.Conn, mgr *accounts.Manager) *RemoteFrontend {
+	return &RemoteFrontend{false, mgr, json.NewDecoder(conn), json.NewEncoder(conn), 0}
+}
+
+// Enable will enable user interaction
+func (fe *RemoteFrontend) Enable() {
+	fe.enabled = true
+}
+
+// UnlockAccount asks the user agent for the user password and tries to unlock the account.
+// It will try 3 attempts before giving up.
+func (fe *RemoteFrontend) UnlockAccount(address []byte) bool {
+	if !fe.enabled {
+		return false
+	}
+
+	err := fe.send(AskPasswordMethod, common.Bytes2Hex(address))
+	if err != nil {
+		glog.V(logger.Error).Infof("Unable to send password request to agent - %v\n", err)
+		return false
+	}
+
+	passwdRes, err := fe.recv()
+	if err != nil {
+		glog.V(logger.Error).Infof("Unable to recv password response from agent - %v\n", err)
+		return false
+	}
+
+	if passwd, ok := passwdRes.Result.(string); ok {
+		err = fe.mgr.Unlock(common.BytesToAddress(address), passwd)
+	}
+
+	if err == nil {
+		return true
+	}
+
+	glog.V(logger.Debug).Infoln("3 invalid account unlock attempts")
+	return false
+}
+
+// ConfirmTransaction asks the user for approval
+func (fe *RemoteFrontend) ConfirmTransaction(tx string) bool {
+	if !fe.enabled {
+		return true // backwards compatibility
+	}
+
+	err := fe.send(ConfirmTransactionMethod, tx)
+	if err != nil {
+		glog.V(logger.Error).Infof("Unable to send tx confirmation request to agent - %v\n", err)
+		return false
+	}
+
+	confirmResponse, err := fe.recv()
+	if err != nil {
+		glog.V(logger.Error).Infof("Unable to recv tx confirmation response from agent - %v\n", err)
+		return false
+	}
+
+	if confirmed, ok := confirmResponse.Result.(bool); ok {
+		return confirmed
+	}
+
+	return false
+}
+
+// send request to the agent
+func (fe *RemoteFrontend) send(method string, params ...interface{}) error {
+	fe.n += 1
+
+	p, err := json.Marshal(params)
+	if err != nil {
+		glog.V(logger.Info).Infof("Unable to send agent request %v\n", err)
+		return err
+	}
+
+	req := shared.Request{
+		Method:  method,
+		Jsonrpc: shared.JsonRpcVersion,
+		Id:      fe.n,
+		Params:  p,
+	}
+
+	return fe.e.Encode(&req)
+}
+
+// recv user response from agent
+func (fe *RemoteFrontend) recv() (*shared.SuccessResponse, error) {
+	var res json.RawMessage
+	if err := fe.d.Decode(&res); err != nil {
+		return nil, err
+	}
+
+	var response shared.SuccessResponse
+	if err := json.Unmarshal(res, &response); err == nil {
+		return &response, nil
+	}
+
+	return nil, fmt.Errorf("Invalid user agent response")
+}