transport,grpc: Integrate delegating resolver and introduce dial options for target host resolution

internal/proxyattributes/proxyattributes.go

@@ -33,8 +33,7 @@ const proxyOptionsKey = keyType("grpc.resolver.delegatingresolver.proxyOptions")
 // Options holds the proxy connection details needed during the CONNECT
 // handshake.
 type Options struct {
-	User        url.Userinfo
-	UserSet     bool
+	User        *url.Userinfo
 	ConnectAddr string
 }
 
@@ -45,7 +44,8 @@ func Set(addr resolver.Address, opts Options) resolver.Address {
 }
 
 // Get returns the Options for the proxy [resolver.Address] and a boolean
-// value representing if the attribute is present or not.
+// value representing if the attribute is present or not. The returned data
+// should not be mutated.
 func Get(addr resolver.Address) (Options, bool) {
 	if a := addr.Attributes.Value(proxyOptionsKey); a != nil {
 		return a.(Options), true

internal/proxyattributes/proxyattributes_test.go

@@ -42,8 +42,7 @@ func (s) TestGet(t *testing.T) {
 		name            string
 		addr            resolver.Address
 		wantConnectAddr string
-		wantUser        url.Userinfo
-		wantUserSet     bool
+		wantUser        *url.Userinfo
 		wantAttrPresent bool
 	}{
 		{
@@ -62,12 +61,10 @@ func (s) TestGet(t *testing.T) {
 			addr: resolver.Address{
 				Addr: "test-address",
 				Attributes: attributes.New(proxyOptionsKey, Options{
-					User:    *user,
-					UserSet: true,
+					User: user,
 				}),
 			},
-			wantUser:        *user,
-			wantUserSet:     true,
+			wantUser:        user,
 			wantAttrPresent: true,
 		},
 		{
@@ -91,9 +88,6 @@ func (s) TestGet(t *testing.T) {
 			if gotOption.User != tt.wantUser {
 				t.Errorf("User(%v) = %v, want %v", tt.addr, gotOption.User, tt.wantUser)
 			}
-			if gotOption.UserSet != tt.wantUserSet {
-				t.Errorf("UserSet(%v) = %v, want %v", tt.addr, gotOption.UserSet, tt.wantUserSet)
-			}
 		})
 	}
 }
@@ -103,8 +97,7 @@ func (s) TestGet(t *testing.T) {
 func (s) TestSet(t *testing.T) {
 	addr := resolver.Address{Addr: "test-address"}
 	pOpts := Options{
-		User:        *url.UserPassword("username", "password"),
-		UserSet:     true,
+		User:        url.UserPassword("username", "password"),
 		ConnectAddr: "proxy-address",
 	}
 
@@ -120,7 +113,4 @@ func (s) TestSet(t *testing.T) {
 	if got, want := gotOption.User, pOpts.User; got != want {
 		t.Errorf("unexpected User proxy attribute = %v, want %v", got, want)
 	}
-	if got, want := gotOption.UserSet, pOpts.UserSet; got != want {
-		t.Errorf("unexpected UserSet proxy attribute = %v, want %v", got, want)
-	}
 }

internal/resolver/delegatingresolver/delegatingresolver.go

@@ -205,16 +205,9 @@ func (r *delegatingResolver) updateClientConnStateLocked() error {
 		proxyAddr = resolver.Address{Addr: r.proxyURL.Host}
 	}
 	var addresses []resolver.Address
-	var user url.Userinfo
-	var userSet bool
-	if r.proxyURL.User != nil {
-		user = *r.proxyURL.User
-		userSet = true
-	}
 	for _, targetAddr := range (*r.targetResolverState).Addresses {
 		addresses = append(addresses, proxyattributes.Set(proxyAddr, proxyattributes.Options{
-			User:        user,
-			UserSet:     userSet,
+			User:        r.proxyURL.User,
 			ConnectAddr: targetAddr.Addr,
 		}))
 	}
@@ -232,8 +225,7 @@ func (r *delegatingResolver) updateClientConnStateLocked() error {
 		for _, proxyAddr := range r.proxyAddrs {
 			for _, targetAddr := range endpt.Addresses {
 				addrs = append(addrs, proxyattributes.Set(proxyAddr, proxyattributes.Options{
-					User:        user,
-					UserSet:     userSet,
+					User:        r.proxyURL.User,
 					ConnectAddr: targetAddr.Addr,
 				}))
 			}

internal/testutils/proxyserver/proxyserver.go

@@ -59,12 +59,12 @@
 func (p *ProxyServer) handleRequest(t *testing.T, in net.Conn, waitForServerHello bool) {
 	req, err := http.ReadRequest(bufio.NewReader(in))
 	if err != nil {
 		t.Errorf("failed to read CONNECT req: %v", err)
 		return
 	}
 	if req.Method != http.MethodConnect {
 		t.Errorf("unexpected Method %q, want %q", req.Method, http.MethodConnect)
 	}
 	p.onRequest(req)
 
 	t.Logf("Dialing to %s", req.URL.Host)
@@ -87,11 +87,11 @@
 		b := make([]byte, 50)
 		bytesRead, err := out.Read(b)
 		if err != nil {
 			t.Errorf("Got error while reading server hello: %v", err)
 			in.Close()
 			out.Close()
 			return
 		}
 		buf.Write(b[0:bytesRead])
 	}
 	p.in = in
@@ -102,19 +102,22 @@
 	go io.Copy(p.out, p.in)
 }
 
-// HTTPProxy initializes and starts a proxy server, registers a cleanup to
+// NewHTTPProxy initializes and starts a proxy server, registers a cleanup to
 // stop it, and returns a ProxyServer.
-func HTTPProxy(t *testing.T, reqCheck func(*http.Request), waitForServerHello bool) *ProxyServer {
+func NewHTTPProxy(t *testing.T, reqCheck func(*http.Request), waitForServerHello bool) *ProxyServer {
 	t.Helper()
 	pLis, err := testutils.LocalTCPListener()
 	if err != nil {
 		t.Fatalf("failed to listen: %v", err)
 	}
 
 	p := &ProxyServer{
 		lis:       pLis,
 		onRequest: reqCheck,
-		Addr:      fmt.Sprintf("localhost:%d", testutils.ParsePort(t, pLis.Addr().String())),
+		// Use "localhost:<port>" to verify the proxy address is handled
+		// correctly by the delegating resolver and connects to the proxy server
+		// correctly even when unresolved.
+		Addr: fmt.Sprintf("localhost:%d", testutils.ParsePort(t, pLis.Addr().String())),
 	}
 
 	// Start the proxy server.

internal/transport/proxy.go

@@ -66,9 +66,7 @@ func doHTTPConnectHandshake(ctx context.Context, conn net.Conn, grpcUA string, o
 		URL:    &url.URL{Host: opts.ConnectAddr},
 		Header: map[string][]string{"User-Agent": {grpcUA}},
 	}
-
-	if userSet := opts.UserSet; userSet {
-		user := opts.User
+	if user := opts.User; user != nil {
 		u := user.Username()
 		p, _ := user.Password()
 		req.Header.Add(proxyAuthHeaderKey, "Basic "+basicAuth(u, p))

internal/transport/proxy_ext_test.go

@@ -88,7 +88,7 @@ func (s) TestGRPCDialWithProxy(t *testing.T) {
 			t.Errorf(" Unexpected request host: %s , want = %s ", got, want)
 		}
 	}
-	pServer := proxyserver.HTTPProxy(t, reqCheck, false)
+	pServer := proxyserver.NewHTTPProxy(t, reqCheck, false)
 
 	// Overwrite the function in the test and restore them in defer.
 	hpfe := func(req *http.Request) (*url.URL, error) {
@@ -145,7 +145,7 @@ func (s) TestGRPCDialWithDNSAndProxy(t *testing.T) {
 			t.Errorf("isIPAddr(%q) = %t, want = %t", host, got, want)
 		}
 	}
-	pServer := proxyserver.HTTPProxy(t, reqCheck, false)
+	pServer := proxyserver.NewHTTPProxy(t, reqCheck, false)
 
 	// Overwrite the function in the test and restore them in defer.
 	hpfe := func(req *http.Request) (*url.URL, error) {
@@ -200,7 +200,7 @@ func (s) TestNewClientWithProxy(t *testing.T) {
 			t.Errorf(" Unexpected request host: %s , want = %s ", got, want)
 		}
 	}
-	pServer := proxyserver.HTTPProxy(t, reqCheck, false)
+	pServer := proxyserver.NewHTTPProxy(t, reqCheck, false)
 
 	// Overwrite the function in the test and restore them in defer.
 	hpfe := func(req *http.Request) (*url.URL, error) {
@@ -254,7 +254,7 @@ func (s) TestNewClientWithProxyAndCustomResolver(t *testing.T) {
 			t.Errorf("isIPAddr(%q) = %t, want = %t", host, got, want)
 		}
 	}
-	pServer := proxyserver.HTTPProxy(t, reqCheck, false)
+	pServer := proxyserver.NewHTTPProxy(t, reqCheck, false)
 
 	// Overwrite the function in the test and restore them in defer.
 	hpfe := func(req *http.Request) (*url.URL, error) {
@@ -316,7 +316,7 @@ func (s) TestNewClientWithProxyAndTargetResolutionEnabled(t *testing.T) {
 			t.Errorf("isIPAddr(%q) = %t, want = %t", host, got, want)
 		}
 	}
-	pServer := proxyserver.HTTPProxy(t, reqCheck, false)
+	pServer := proxyserver.NewHTTPProxy(t, reqCheck, false)
 
 	// Overwrite the function in the test and restore them in defer.
 	hpfe := func(req *http.Request) (*url.URL, error) {
@@ -361,7 +361,7 @@ func (s) TestNewClientWithNoProxy(t *testing.T) {
 	backend := startBackendServer(t)
 	unresolvedTargetURI := fmt.Sprintf("localhost:%d", testutils.ParsePort(t, backend.Address))
 	reqCheck := func(_ *http.Request) { t.Error("proxy server should not have received a Connect request") }
-	pServer := proxyserver.HTTPProxy(t, reqCheck, false)
+	pServer := proxyserver.NewHTTPProxy(t, reqCheck, false)
 
 	// Overwrite the function in the test and restore them in defer.
 	hpfe := func(req *http.Request) (*url.URL, error) {
@@ -406,7 +406,7 @@ func (s) TestNewClientWithContextDialer(t *testing.T) {
 	backend := startBackendServer(t)
 	unresolvedTargetURI := fmt.Sprintf("localhost:%d", testutils.ParsePort(t, backend.Address))
 	reqCheck := func(_ *http.Request) { t.Error("proxy server should not have received a Connect request") }
-	pServer := proxyserver.HTTPProxy(t, reqCheck, false)
+	pServer := proxyserver.NewHTTPProxy(t, reqCheck, false)
 
 	// Overwrite the function in the test and restore them in defer.
 	hpfe := func(req *http.Request) (*url.URL, error) {
@@ -475,7 +475,7 @@ func (s) TestBasicAuthInNewClientWithProxy(t *testing.T) {
 			t.Errorf("unexpected auth %q (%q), want %q (%q)", got, gotDecoded, wantProxyAuthStr, wantDecoded)
 		}
 	}
-	pServer := proxyserver.HTTPProxy(t, reqCheck, false)
+	pServer := proxyserver.NewHTTPProxy(t, reqCheck, false)
 
 	t.Setenv("HTTPS_PROXY", user+":"+password+"@"+pServer.Addr)
 

internal/transport/proxy_test.go

@@ -54,7 +54,7 @@ func (s) TestHTTPConnectWithServerHello(t *testing.T) {
 			t.Error(err)
 		}
 	}
-	pServer := proxyserver.HTTPProxy(t, reqCheck, true)
+	pServer := proxyserver.NewHTTPProxy(t, reqCheck, true)
 
 	msg := []byte{4, 3, 5, 2}
 	recvBuf := make([]byte, len(msg))