control/controlhttp: remove ClientConn.UntrustedUpgradeHeaders

It was just added and unreleased but we've decided to go a different route.

Details are in 5e9e57ecf531f.

Updates #5972

Change-Id: I49016af469225f58535f63a9b0fbe5ab6a5bf304
Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>

control/controlhttp/client.go

@@ -336,7 +336,7 @@ func (a *Dialer) dialURL(ctx context.Context, u *url.URL, addr netip.Addr) (*Cli
 	if err != nil {
 		return nil, err
 	}
-	netConn, untrustedUpgradeHeaders, err := a.tryURLUpgrade(ctx, u, addr, init)
+	netConn, err := a.tryURLUpgrade(ctx, u, addr, init)
 	if err != nil {
 		return nil, err
 	}
@@ -347,7 +347,6 @@ func (a *Dialer) dialURL(ctx context.Context, u *url.URL, addr netip.Addr) (*Cli
 	}
 	return &ClientConn{
 		Conn: cbConn,
-		UntrustedUpgradeHeaders: untrustedUpgradeHeaders,
 	}, nil
 }
 
@@ -356,7 +355,7 @@ func (a *Dialer) dialURL(ctx context.Context, u *url.URL, addr netip.Addr) (*Cli
 // provided address.
 //
 // Only the provided ctx is used, not a.ctx.
-func (a *Dialer) tryURLUpgrade(ctx context.Context, u *url.URL, addr netip.Addr, init []byte) (_ net.Conn, untrustedUpgradeHeaders http.Header, _ error) {
+func (a *Dialer) tryURLUpgrade(ctx context.Context, u *url.URL, addr netip.Addr, init []byte) (net.Conn, error) {
 	var dns *dnscache.Resolver
 
 	// If we were provided an address to dial, then create a resolver that just
@@ -438,11 +437,11 @@ func (a *Dialer) tryURLUpgrade(ctx context.Context, u *url.URL, addr netip.Addr,
 
 	resp, err := tr.RoundTrip(req)
 	if err != nil {
-		return nil, nil, err
+		return nil, err
 	}
 
 	if resp.StatusCode != http.StatusSwitchingProtocols {
-		return nil, nil, fmt.Errorf("unexpected HTTP response: %s", resp.Status)
+		return nil, fmt.Errorf("unexpected HTTP response: %s", resp.Status)
 	}
 
 	// From here on, the underlying net.Conn is ours to use, but there
@@ -456,19 +455,19 @@ func (a *Dialer) tryURLUpgrade(ctx context.Context, u *url.URL, addr netip.Addr,
 	}
 	if switchedConn == nil {
 		resp.Body.Close()
-		return nil, nil, fmt.Errorf("httptrace didn't provide a connection")
+		return nil, fmt.Errorf("httptrace didn't provide a connection")
 	}
 
 	if next := resp.Header.Get("Upgrade"); next != upgradeHeaderValue {
 		resp.Body.Close()
-		return nil, nil, fmt.Errorf("server switched to unexpected protocol %q", next)
+		return nil, fmt.Errorf("server switched to unexpected protocol %q", next)
 	}
 
 	rwc, ok := resp.Body.(io.ReadWriteCloser)
 	if !ok {
 		resp.Body.Close()
-		return nil, nil, errors.New("http Transport did not provide a writable body")
+		return nil, errors.New("http Transport did not provide a writable body")
 	}
 
-	return netutil.NewAltReadWriteCloserConn(rwc, switchedConn), resp.Header, nil
+	return netutil.NewAltReadWriteCloserConn(rwc, switchedConn), nil
 }

control/controlhttp/client_common.go

@@ -5,8 +5,6 @@
 package controlhttp
 
 import (
-	"net/http"
-
 	"tailscale.com/control/controlbase"
 )
 
@@ -17,10 +15,4 @@ import (
 type ClientConn struct {
 	// Conn is the noise connection.
 	*controlbase.Conn
-
-	// UntrustedUpgradeHeaders are the HTTP headers seen in the
-	// 101 Switching Protocols upgrade response. They may be nil
-	// or even might've been tampered with by a middlebox.
-	// They should not be trusted.
-	UntrustedUpgradeHeaders http.Header
 }

control/controlhttp/client_js.go

@@ -46,7 +46,7 @@ func (d *Dialer) Dial(ctx context.Context) (*ClientConn, error) {
 			handshakeHeaderName: []string{base64.StdEncoding.EncodeToString(init)},
 		}.Encode(),
 	}
-	wsConn, httpRes, err := websocket.Dial(ctx, wsURL.String(), &websocket.DialOptions{
+	wsConn, _, err := websocket.Dial(ctx, wsURL.String(), &websocket.DialOptions{
 		Subprotocols: []string{upgradeHeaderValue},
 	})
 	if err != nil {
@@ -58,8 +58,5 @@ func (d *Dialer) Dial(ctx context.Context) (*ClientConn, error) {
 		netConn.Close()
 		return nil, err
 	}
-	return &ClientConn{
+	return &ClientConn{Conn: cbConn}, nil
-		Conn:                    cbConn,
-		UntrustedUpgradeHeaders: httpRes.Header,
-	}, nil
 }