Implement websocket (ws:// and wss://) links (#1152)

ws:// can be listened and dialed
wss:// is a convenience link for ws:// that supports dialing to ws://
peer.

---------

Signed-off-by: Vasyl Gello <vasek.gello@gmail.com>
Co-authored-by: Neil Alexander <neilalexander@users.noreply.github.com>

go.mod

@@ -19,6 +19,7 @@ require (
 	golang.org/x/text v0.16.0
 	golang.zx2c4.com/wireguard v0.0.0-20231211153847-12269c276173
 	golang.zx2c4.com/wireguard/windows v0.5.3
+	nhooyr.io/websocket v1.8.11
 )
 
 require (

go.sum

@@ -154,3 +154,5 @@ gopkg.in/yaml.v3 v3.0.1 h1:fxVm/GzAzEWqLHuvctI91KS9hhNmmWOoWu0XTYJS7CA=
 gopkg.in/yaml.v3 v3.0.1/go.mod h1:K4uyk7z7BCEPqu6E+C64Yfv1cQ7kz7rIZviUmN+EgEM=
 gvisor.dev/gvisor v0.0.0-20230927004350-cbd86285d259 h1:TbRPT0HtzFP3Cno1zZo7yPzEEnfu8EjLfl6IU9VfqkQ=
 gvisor.dev/gvisor v0.0.0-20230927004350-cbd86285d259/go.mod h1:AVgIgHMwK63XvmAzWG9vLQ41YnVHN0du0tEC46fI7yY=
+nhooyr.io/websocket v1.8.11 h1:f/qXNc2/3DpoSZkHt1DQu6rj4zGC8JmkkLkWss0MgN0=
+nhooyr.io/websocket v1.8.11/go.mod h1:rN9OFWIUwuxg4fR5tELlYC04bXYowCP9GX47ivo2l+c=

src/core/link.go

@@ -37,6 +37,8 @@ type links struct {
 	unix  *linkUNIX  // UNIX interface support
 	socks *linkSOCKS // SOCKS interface support
 	quic  *linkQUIC  // QUIC interface support
+	ws    *linkWS    // WS interface support
+	wss   *linkWSS   // WSS interface support
 	// _links can only be modified safely from within the links actor
 	_links map[linkInfo]*link // *link is nil if connection in progress
 }
@@ -97,6 +99,8 @@ func (l *links) init(c *Core) error {
 	l.unix = l.newLinkUNIX()
 	l.socks = l.newLinkSOCKS()
 	l.quic = l.newLinkQUIC()
+	l.ws = l.newLinkWS()
+	l.wss = l.newLinkWSS()
 	l._links = make(map[linkInfo]*link)
 
 	var listeners []ListenAddress
@@ -417,6 +421,10 @@ func (l *links) listen(u *url.URL, sintf string) (*Listener, error) {
 		protocol = l.unix
 	case "quic":
 		protocol = l.quic
+	case "ws":
+		protocol = l.ws
+	case "wss":
+		protocol = l.wss
 	default:
 		cancel()
 		return nil, ErrLinkUnrecognisedSchema
@@ -545,6 +553,10 @@ func (l *links) connect(ctx context.Context, u *url.URL, info linkInfo, options
 		dialer = l.unix
 	case "quic":
 		dialer = l.quic
+	case "ws":
+		dialer = l.ws
+	case "wss":
+		dialer = l.wss
 	default:
 		return nil, ErrLinkUnrecognisedSchema
 	}

src/core/link_ws.go

@@ -0,0 +1,123 @@
+package core
+
+import (
+	"context"
+	"net"
+	"net/http"
+	"net/url"
+	"time"
+
+	"github.com/Arceliar/phony"
+	"nhooyr.io/websocket"
+)
+
+type linkWS struct {
+	phony.Inbox
+	*links
+}
+
+type linkWSConn struct {
+	net.Conn
+}
+
+type linkWSListener struct {
+	ch         chan *linkWSConn
+	ctx        context.Context
+	httpServer *http.Server
+	listener   net.Listener
+}
+
+type wsServer struct {
+	ch  chan *linkWSConn
+	ctx context.Context
+}
+
+func (l *linkWSListener) Accept() (net.Conn, error) {
+	qs := <-l.ch
+	if qs == nil {
+		return nil, context.Canceled
+	}
+	return qs, nil
+}
+
+func (l *linkWSListener) Addr() net.Addr {
+	return l.listener.Addr()
+}
+
+func (l *linkWSListener) Close() error {
+	if err := l.httpServer.Shutdown(l.ctx); err != nil {
+		return err
+	}
+	return l.listener.Close()
+}
+
+func (s *wsServer) ServeHTTP(w http.ResponseWriter, r *http.Request) {
+	if r.URL.Path == "/health" || r.URL.Path == "/healthz" {
+		w.WriteHeader(http.StatusOK)
+		_, _ = w.Write([]byte("OK"))
+		return
+	}
+
+	c, err := websocket.Accept(w, r, &websocket.AcceptOptions{
+		Subprotocols: []string{"ygg-ws"},
+	})
+	if err != nil {
+		return
+	}
+
+	if c.Subprotocol() != "ygg-ws" {
+		c.Close(websocket.StatusPolicyViolation, "client must speak the ygg-ws subprotocol")
+		return
+	}
+
+	s.ch <- &linkWSConn{
+		Conn: websocket.NetConn(s.ctx, c, websocket.MessageBinary),
+	}
+}
+
+func (l *links) newLinkWS() *linkWS {
+	lt := &linkWS{
+		links: l,
+	}
+	return lt
+}
+
+func (l *linkWS) dial(ctx context.Context, url *url.URL, info linkInfo, options linkOptions) (net.Conn, error) {
+	wsconn, _, err := websocket.Dial(ctx, url.String(), &websocket.DialOptions{
+		Subprotocols: []string{"ygg-ws"},
+	})
+	if err != nil {
+		return nil, err
+	}
+	return &linkWSConn{
+		Conn: websocket.NetConn(ctx, wsconn, websocket.MessageBinary),
+	}, nil
+}
+
+func (l *linkWS) listen(ctx context.Context, url *url.URL, _ string) (net.Listener, error) {
+	nl, err := net.Listen("tcp", url.Host)
+	if err != nil {
+		return nil, err
+	}
+
+	ch := make(chan *linkWSConn)
+
+	httpServer := &http.Server{
+		Handler: &wsServer{
+			ch:  ch,
+			ctx: ctx,
+		},
+		BaseContext:  func(_ net.Listener) context.Context { return ctx },
+		ReadTimeout:  time.Second * 10,
+		WriteTimeout: time.Second * 10,
+	}
+
+	lwl := &linkWSListener{
+		ch:         ch,
+		ctx:        ctx,
+		httpServer: httpServer,
+		listener:   nl,
+	}
+	go lwl.httpServer.Serve(nl) // nolint:errcheck
+	return lwl, nil
+}

src/core/link_wss.go

@@ -0,0 +1,43 @@
+package core
+
+import (
+	"context"
+	"fmt"
+	"net"
+	"net/url"
+
+	"github.com/Arceliar/phony"
+	"nhooyr.io/websocket"
+)
+
+type linkWSS struct {
+	phony.Inbox
+	*links
+}
+
+type linkWSSConn struct {
+	net.Conn
+}
+
+func (l *links) newLinkWSS() *linkWSS {
+	lwss := &linkWSS{
+		links: l,
+	}
+	return lwss
+}
+
+func (l *linkWSS) dial(ctx context.Context, url *url.URL, info linkInfo, options linkOptions) (net.Conn, error) {
+	wsconn, _, err := websocket.Dial(ctx, url.String(), &websocket.DialOptions{
+		Subprotocols: []string{"ygg-ws"},
+	})
+	if err != nil {
+		return nil, err
+	}
+	return &linkWSSConn{
+		Conn: websocket.NetConn(ctx, wsconn, websocket.MessageBinary),
+	}, nil
+}
+
+func (l *linkWSS) listen(ctx context.Context, url *url.URL, _ string) (net.Listener, error) {
+	return nil, fmt.Errorf("WSS listener not supported, use WS listener behind reverse proxy instead")
+}