Merge pull request #734 from bas-vk/issue-729

admin.StopRPC added to console

2 files changed, 120 insertions, 4 deletions

diff --git a/rpc/http.go b/rpc/http.go
index 790442a28..f9c646908 100644
--- a/rpc/http.go
+++ b/rpc/http.go
@@ -5,7 +5,6 @@ import (
 	"fmt"
 	"io"
 	"io/ioutil"
-	"net"
 	"net/http"
 
 	"github.com/ethereum/go-ethereum/logger"
@@ -15,6 +14,7 @@ import (
 )
 
 var rpclogger = logger.NewLogger("RPC")
+var rpclistener *stoppableTCPListener
 
 const (
 	jsonrpcver       = "2.0"
@@ -22,11 +22,19 @@ const (
 )
 
 func Start(pipe *xeth.XEth, config RpcConfig) error {
-	l, err := net.Listen("tcp", fmt.Sprintf("%s:%d", config.ListenAddress, config.ListenPort))
+	if rpclistener != nil {
+		if fmt.Sprintf("%s:%d", config.ListenAddress, config.ListenPort) != rpclistener.Addr().String() {
+			return fmt.Errorf("RPC service already running on %s ", rpclistener.Addr().String())
+		}
+		return nil // RPC service already running on given host/port
+	}
+
+	l, err := newStoppableTCPListener(fmt.Sprintf("%s:%d", config.ListenAddress, config.ListenPort))
 	if err != nil {
 		rpclogger.Errorf("Can't listen on %s:%d: %v", config.ListenAddress, config.ListenPort, err)
 		return err
 	}
+	rpclistener = l
 
 	var handler http.Handler
 	if len(config.CorsDomain) > 0 {
@@ -35,9 +43,9 @@ func Start(pipe *xeth.XEth, config RpcConfig) error {
 		opts.AllowedOrigins = []string{config.CorsDomain}
 
 		c := cors.New(opts)
-		handler = c.Handler(JSONRPC(pipe))
+		handler = newStoppableHandler(c.Handler(JSONRPC(pipe)), l.stop)
 	} else {
-		handler = JSONRPC(pipe)
+		handler = newStoppableHandler(JSONRPC(pipe), l.stop)
 	}
 
 	go http.Serve(l, handler)
@@ -45,6 +53,15 @@ func Start(pipe *xeth.XEth, config RpcConfig) error {
 	return nil
 }
 
+func Stop() error {
+	if rpclistener != nil {
+		rpclistener.Stop()
+		rpclistener = nil
+	}
+
+	return nil
+}
+
 // JSONRPC returns a handler that implements the Ethereum JSON-RPC API.
 func JSONRPC(pipe *xeth.XEth) http.Handler {
 	api := NewEthereumApi(pipe)
diff --git a/rpc/types.go b/rpc/types.go
index bc9a46ed5..1784759a4 100644
--- a/rpc/types.go
+++ b/rpc/types.go
@@ -23,6 +23,13 @@ import (
 	"math/big"
 	"strings"
 
+	"errors"
+	"net"
+	"net/http"
+	"time"
+
+	"io"
+
 	"github.com/ethereum/go-ethereum/common"
 	"github.com/ethereum/go-ethereum/core/types"
 )
@@ -257,3 +264,95 @@ type RpcErrorObject struct {
 	Message string `json:"message"`
 	// Data    interface{} `json:"data"`
 }
+
+type listenerHasStoppedError struct {
+	msg string
+}
+
+func (self listenerHasStoppedError) Error() string {
+	return self.msg
+}
+
+var listenerStoppedError = listenerHasStoppedError{"Listener stopped"}
+
+// When https://github.com/golang/go/issues/4674 is fixed this could be replaced
+type stoppableTCPListener struct {
+	*net.TCPListener
+	stop chan struct{} // closed when the listener must stop
+}
+
+// Wraps the default handler and checks if the RPC service was stopped. In that case it returns an
+// error indicating that the service was stopped. This will only happen for connections which are
+// kept open (HTTP keep-alive) when the RPC service was shutdown.
+func newStoppableHandler(h http.Handler, stop chan struct{}) http.Handler {
+	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		select {
+		case <-stop:
+			w.Header().Set("Content-Type", "application/json")
+			jsonerr := &RpcErrorObject{-32603, "RPC service stopped"}
+			send(w, &RpcErrorResponse{Jsonrpc: jsonrpcver, Id: nil, Error: jsonerr})
+		default:
+			h.ServeHTTP(w, r)
+		}
+	})
+}
+
+// Stop the listener and all accepted and still active connections.
+func (self *stoppableTCPListener) Stop() {
+	close(self.stop)
+}
+
+func newStoppableTCPListener(addr string) (*stoppableTCPListener, error) {
+	wl, err := net.Listen("tcp", addr)
+	if err != nil {
+		return nil, err
+	}
+
+	if tcpl, ok := wl.(*net.TCPListener); ok {
+		stop := make(chan struct{})
+		l := &stoppableTCPListener{tcpl, stop}
+		return l, nil
+	}
+
+	return nil, errors.New("Unable to create TCP listener for RPC service")
+}
+
+func (self *stoppableTCPListener) Accept() (net.Conn, error) {
+	for {
+		self.SetDeadline(time.Now().Add(time.Duration(1 * time.Second)))
+		c, err := self.TCPListener.AcceptTCP()
+
+		select {
+		case <-self.stop:
+			if c != nil { // accept timeout
+				c.Close()
+			}
+			self.TCPListener.Close()
+			return nil, listenerStoppedError
+		default:
+		}
+
+		if err != nil {
+			if netErr, ok := err.(net.Error); ok && netErr.Timeout() && netErr.Temporary() {
+				continue // regular timeout
+			}
+		}
+
+		return &closableConnection{c, self.stop}, err
+	}
+}
+
+type closableConnection struct {
+	*net.TCPConn
+	closed chan struct{}
+}
+
+func (self *closableConnection) Read(b []byte) (n int, err error) {
+	select {
+	case <-self.closed:
+		self.TCPConn.Close()
+		return 0, io.EOF
+	default:
+		return self.TCPConn.Read(b)
+	}
+}