Merge pull request #974 from draios/ws-proxy-path-option

Add WS ProxyPath option

nats.go

@@ -467,6 +467,10 @@ type Options struct {
 	// supports compression. If the server does too, then data will be compressed.
 	Compression bool
 
+	// For websocket connections, adds a path to connections url.
+	// This is useful when connecting to NATS behind a proxy.
+	ProxyPath string
+
 	// InboxPrefix allows the default _INBOX prefix to be customized
 	InboxPrefix string
 }
@@ -1147,6 +1151,15 @@ func Compression(enabled bool) Option {
 	}
 }
 
+// ProxyPath is an option for websocket connections that adds a path to connections url.
+// This is useful when connecting to NATS behind a proxy.
+func ProxyPath(path string) Option {
+	return func(o *Options) error {
+		o.ProxyPath = path
+		return nil
+	}
+}
+
 // CustomInboxPrefix configures the request + reply inbox prefix
 func CustomInboxPrefix(p string) Option {
 	return func(o *Options) error {

ws.go

@@ -570,6 +570,15 @@ func (nc *Conn) wsInitHandshake(u *url.URL) error {
 		scheme = "https"
 	}
 	ustr := fmt.Sprintf("%s://%s", scheme, u.Host)
+
+	if nc.Opts.ProxyPath != "" {
+		proxyPath := nc.Opts.ProxyPath
+		if !strings.HasPrefix(proxyPath, "/") {
+			proxyPath = "/" + proxyPath
+		}
+		ustr += proxyPath
+	}
+
 	u, err = url.Parse(ustr)
 	if err != nil {
 		return err

ws_test.go

@@ -16,11 +16,14 @@ package nats
 import (
 	"bytes"
 	"compress/flate"
+	"context"
 	"crypto/tls"
 	"encoding/binary"
 	"fmt"
 	"io"
 	"math/rand"
+	"net"
+	"net/http"
 	"reflect"
 	"runtime"
 	"strings"
@@ -1108,3 +1111,50 @@ func TestWSNoDeadlockOnAuthFailure(t *testing.T) {
 
 	tm.Stop()
 }
+
+func TestWSProxyPath(t *testing.T) {
+	const proxyPath = "proxy1"
+
+	// Listen to a random port
+	l, err := net.Listen("tcp", ":0")
+	if err != nil {
+		t.Fatalf("Error in listen: %v", err)
+	}
+	defer l.Close()
+
+	proxyPort := l.Addr().(*net.TCPAddr).Port
+
+	ch := make(chan struct{}, 1)
+	proxySrv := &http.Server{
+		Handler: http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+			if r.URL.Path == "/"+proxyPath {
+				ch <- struct{}{}
+			}
+		}),
+	}
+	defer proxySrv.Shutdown(context.Background())
+	go proxySrv.Serve(l)
+
+	for _, test := range []struct {
+		name string
+		path string
+	}{
+		{"without slash", proxyPath},
+		{"with slash", "/" + proxyPath},
+	} {
+		t.Run(test.name, func(t *testing.T) {
+			url := fmt.Sprintf("ws://127.0.0.1:%d", proxyPort)
+			nc, err := Connect(url, ProxyPath(test.path))
+			if err == nil {
+				nc.Close()
+				t.Fatal("Did not expect to connect")
+			}
+			select {
+			case <-ch:
+				// OK:
+			case <-time.After(time.Second):
+				t.Fatal("Proxy was not reached")
+			}
+		})
+	}
+}