add supported for ws in reverse proxy

config/setup/rewrite_test.go

@@ -4,8 +4,9 @@ import (
 	"testing"
 
 	"fmt"
-	"github.com/mholt/caddy/middleware/rewrite"
 	"regexp"
+
+	"github.com/mholt/caddy/middleware/rewrite"
 )
 
 func TestRewrite(t *testing.T) {

middleware/proxy/reverseproxy.go

@@ -16,6 +16,8 @@ import (
 	"time"
 )
 
+const HTTPSwitchProtocols = 101
+
 // onExitFlushLoop is a callback set by tests to detect the state of the
 // flushLoop() goroutine.
 var onExitFlushLoop func()
@@ -153,8 +155,37 @@ func (p *ReverseProxy) ServeHTTP(rw http.ResponseWriter, req *http.Request, extr
 
 	copyHeader(rw.Header(), res.Header)
 
+	if res.StatusCode == HTTPSwitchProtocols {
+		hj, ok := rw.(http.Hijacker)
+		if !ok {
+			return nil
+		}
+
+		conn, _, err := hj.Hijack()
+		if err != nil {
+			return err
+		}
+
+		backendConn, err := net.Dial("tcp", outreq.Host)
+		if err != nil {
+			conn.Close()
+			return err
+		}
+
+		outreq.Write(backendConn)
+
+		go func() {
+			io.Copy(backendConn, conn) // write tcp stream to backend.
+			backendConn.Close()
+		}()
+
+		io.Copy(conn, backendConn) // read tcp stream from backend.
+		conn.Close()
+	} else {
 		rw.WriteHeader(res.StatusCode)
 		p.copyResponse(rw, res.Body)
+	}
+
 	return nil
 }