remove the template parameter from the client (#73)

The same UDP proxy could offer proxying functionality at different
paths (and therefore different templates), and we should be able to
multiplex these on the same QUIC connection.

client.go

@@ -20,13 +20,9 @@ import (
 // This allows tunneling QUIC connections, which themselves have a minimum MTU requirement of 1200 bytes.
 const defaultInitialPacketSize = 1350
 
-// A Client establishes proxied connections to remote hosts,
-// using a UDP proxy.
+// A Client establishes proxied connections to remote hosts, using a UDP proxy.
 // Multiple flows can be proxied via the same connection to the proxy.
 type Client struct {
-	// Template is the URI template of the UDP proxy.
-	Template *uritemplate.Template
-
 	// TLSClientConfig is the TLS client config used when dialing the QUIC connection to the proxy.
 	// It must set the "h3" ALPN.
 	TLSClientConfig *tls.Config
@@ -43,15 +39,12 @@ type Client struct {
 // DialAddr dials a proxied connection to a target server.
 // The target address is sent to the proxy, and the DNS resolution is left to the proxy.
 // The target must be given as a host:port.
-func (c *Client) DialAddr(ctx context.Context, target string) (net.PacketConn, *http.Response, error) {
-	if c.Template == nil {
-		return nil, nil, errors.New("masque: no template")
-	}
+func (c *Client) DialAddr(ctx context.Context, proxyTemplate *uritemplate.Template, target string) (net.PacketConn, *http.Response, error) {
 	host, port, err := net.SplitHostPort(target)
 	if err != nil {
 		return nil, nil, fmt.Errorf("failed to parse target: %w", err)
 	}
-	str, err := c.Template.Expand(uritemplate.Values{
+	str, err := proxyTemplate.Expand(uritemplate.Values{
 		uriTemplateTargetHost: uritemplate.String(host),
 		uriTemplateTargetPort: uritemplate.String(port),
 	})
@@ -62,11 +55,8 @@ func (c *Client) DialAddr(ctx context.Context, target string) (net.PacketConn, *
 }
 
 // Dial dials a proxied connection to a target server.
-func (c *Client) Dial(ctx context.Context, raddr *net.UDPAddr) (net.PacketConn, *http.Response, error) {
-	if c.Template == nil {
-		return nil, nil, errors.New("masque: no template")
-	}
-	str, err := c.Template.Expand(uritemplate.Values{
+func (c *Client) Dial(ctx context.Context, proxyTemplate *uritemplate.Template, raddr *net.UDPAddr) (net.PacketConn, *http.Response, error) {
+	str, err := proxyTemplate.Expand(uritemplate.Values{
 		uriTemplateTargetHost: uritemplate.String(escape(raddr.IP.String())),
 		uriTemplateTargetPort: uritemplate.String(strconv.Itoa(raddr.Port)),
 	})

cmd/client/main.go

@@ -34,7 +34,6 @@ func main() {
 	}
 
 	cl := masque.Client{
-		Template: uritemplate.MustNew(proxyURITemplate),
 		QUICConfig: &quic.Config{
 			EnableDatagrams:   true,
 			InitialPacketSize: 1350,
@@ -52,7 +51,7 @@ func main() {
 				if err != nil {
 					return nil, err
 				}
-				pconn, _, err := cl.Dial(context.Background(), raddr)
+				pconn, _, err := cl.Dial(context.Background(), uritemplate.MustNew(proxyURITemplate), raddr)
 				if err != nil {
 					log.Fatal("dialing MASQUE failed:", err)
 				}

connect-udp_test.go

@@ -83,11 +83,14 @@ func testProxyToIP(t *testing.T, addr *net.UDPAddr) {
 	}()
 
 	cl := masque.Client{
-		Template:        template,
 		TLSClientConfig: &tls.Config{ClientCAs: certPool, NextProtos: []string{http3.NextProtoH3}, InsecureSkipVerify: true},
 	}
 	defer cl.Close()
-	proxiedConn, _, err := cl.Dial(context.Background(), remoteServerConn.LocalAddr().(*net.UDPAddr))
+	proxiedConn, _, err := cl.Dial(
+		context.Background(),
+		template,
+		remoteServerConn.LocalAddr().(*net.UDPAddr),
+	)
 	require.NoError(t, err)
 
 	_, err = proxiedConn.WriteTo([]byte("foobar"), remoteServerConn.LocalAddr())
@@ -141,11 +144,10 @@ func TestProxyToHostname(t *testing.T) {
 	}()
 
 	cl := masque.Client{
-		Template:        template,
 		TLSClientConfig: &tls.Config{ClientCAs: certPool, NextProtos: []string{http3.NextProtoH3}, InsecureSkipVerify: true},
 	}
 	defer cl.Close()
-	proxiedConn, rsp, err := cl.DialAddr(context.Background(), "quic-go.net:1234") // the proxy doesn't actually resolve this hostname
+	proxiedConn, rsp, err := cl.DialAddr(context.Background(), template, "quic-go.net:1234") // the proxy doesn't actually resolve this hostname
 	require.NoError(t, err)
 	require.Equal(t, http.StatusOK, rsp.StatusCode)
 
@@ -181,22 +183,24 @@ func TestProxyingRejected(t *testing.T) {
 	}()
 
 	cl := masque.Client{
-		Template:        template,
 		TLSClientConfig: &tls.Config{ClientCAs: certPool, NextProtos: []string{http3.NextProtoH3}, InsecureSkipVerify: true},
 	}
 	defer cl.Close()
-	_, rsp, err := cl.DialAddr(context.Background(), "quic-go.net:1234") // the proxy doesn't actually resolve this hostname
+	_, rsp, err := cl.DialAddr(context.Background(), template, "quic-go.net:1234") // the proxy doesn't actually resolve this hostname
 	require.Error(t, err)
 	require.Equal(t, http.StatusTeapot, rsp.StatusCode)
 }
 
 func TestProxyToHostnameMissingPort(t *testing.T) {
 	cl := masque.Client{
-		Template:        uritemplate.MustNew("https://localhost:1234/masque?h={target_host}&p={target_port}"),
 		TLSClientConfig: &tls.Config{ClientCAs: certPool, NextProtos: []string{http3.NextProtoH3}, InsecureSkipVerify: true},
 	}
 	defer cl.Close()
-	_, rsp, err := cl.DialAddr(context.Background(), "quic-go.net") // missing port
+	_, rsp, err := cl.DialAddr(
+		context.Background(),
+		uritemplate.MustNew("https://localhost:1234/masque?h={target_host}&p={target_port}"),
+		"quic-go.net", // missing port
+	)
 	require.Nil(t, rsp)
 	require.ErrorContains(t, err, "address quic-go.net: missing port in address")
 }
@@ -236,11 +240,10 @@ func TestProxyShutdown(t *testing.T) {
 	}()
 
 	cl := masque.Client{
-		Template:        template,
 		TLSClientConfig: &tls.Config{ClientCAs: certPool, NextProtos: []string{http3.NextProtoH3}, InsecureSkipVerify: true},
 	}
 	defer cl.Close()
-	proxiedConn, rsp, err := cl.Dial(context.Background(), remoteServerConn.LocalAddr().(*net.UDPAddr))
+	proxiedConn, rsp, err := cl.Dial(context.Background(), template, remoteServerConn.LocalAddr().(*net.UDPAddr))
 	require.NoError(t, err)
 	require.Equal(t, http.StatusOK, rsp.StatusCode)