experimental/credentials: Add experimental credentials that don't enforce ALPN

credentials/tls.go

@@ -32,6 +32,8 @@ import (
 	"google.golang.org/grpc/internal/envconfig"
 )
 
+const alpnFailureHelpMessage = "If you upgraded from a grpc-go version earlier than 1.67, your TLS connections may have stopped working due to ALPN enforcement. For more details, see: https://github.com/grpc/grpc-go/issues/434"
+
 var logger = grpclog.Component("credentials")
 
 // TLSInfo contains the auth information for a TLS authenticated connection.
@@ -128,7 +130,7 @@ func (c *tlsCreds) ClientHandshake(ctx context.Context, authority string, rawCon
 	if np == "" {
 		if envconfig.EnforceALPNEnabled {
 			conn.Close()
-			return nil, nil, fmt.Errorf("credentials: cannot check peer: missing selected ALPN property")
+			return nil, nil, fmt.Errorf("credentials: cannot check peer: missing selected ALPN property. %s", alpnFailureHelpMessage)
 		}
 		logger.Warningf("Allowing TLS connection to server %q with ALPN disabled. TLS connections to servers with ALPN disabled will be disallowed in future grpc-go releases", cfg.ServerName)
 	}
@@ -158,7 +160,7 @@ func (c *tlsCreds) ServerHandshake(rawConn net.Conn) (net.Conn, AuthInfo, error)
 	if cs.NegotiatedProtocol == "" {
 		if envconfig.EnforceALPNEnabled {
 			conn.Close()
-			return nil, nil, fmt.Errorf("credentials: cannot check peer: missing selected ALPN property")
+			return nil, nil, fmt.Errorf("credentials: cannot check peer: missing selected ALPN property. %s", alpnFailureHelpMessage)
 		} else if logger.V(2) {
 			logger.Info("Allowing TLS connection from client with ALPN disabled. TLS connections with ALPN disabled will be disallowed in future grpc-go releases")
 		}

experimental/credentials/credentials_test.go

@@ -0,0 +1,252 @@
+/*
+ *
+ * Copyright 2025 gRPC authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ *
+ */
+
+package credentials
+
+import (
+	"context"
+	"crypto/tls"
+	"net"
+	"strings"
+	"testing"
+	"time"
+
+	"google.golang.org/grpc/credentials"
+	"google.golang.org/grpc/internal/grpctest"
+	"google.golang.org/grpc/testdata"
+)
+
+const defaultTestTimeout = 10 * time.Second
+
+type s struct {
+	grpctest.Tester
+}
+
+func Test(t *testing.T) {
+	grpctest.RunSubTests(t, s{})
+}
+
+func (s) TestTLSOverrideServerName(t *testing.T) {
+	expectedServerName := "server.name"
+	c := NewTLSWithALPNDisabled(nil)
+	c.OverrideServerName(expectedServerName)
+	if c.Info().ServerName != expectedServerName {
+		t.Fatalf("c.Info().ServerName = %v, want %v", c.Info().ServerName, expectedServerName)
+	}
+}
+
+func (s) TestTLSClone(t *testing.T) {
+	expectedServerName := "server.name"
+	c := NewTLSWithALPNDisabled(nil)
+	c.OverrideServerName(expectedServerName)
+	cc := c.Clone()
+	if cc.Info().ServerName != expectedServerName {
+		t.Fatalf("cc.Info().ServerName = %v, want %v", cc.Info().ServerName, expectedServerName)
+	}
+	cc.OverrideServerName("")
+	if c.Info().ServerName != expectedServerName {
+		t.Fatalf("Change in clone should not affect the original, c.Info().ServerName = %v, want %v", c.Info().ServerName, expectedServerName)
+	}
+
+}
+
+type serverHandshake func(net.Conn) (credentials.AuthInfo, error)
+
+func (s) TestClientHandshakeReturnsAuthInfo(t *testing.T) {
+	tcs := []struct {
+		name    string
+		address string
+	}{
+		{
+			name:    "localhost",
+			address: "localhost:0",
+		},
+		{
+			name:    "ipv4",
+			address: "127.0.0.1:0",
+		},
+		{
+			name:    "ipv6",
+			address: "[::1]:0",
+		},
+	}
+
+	for _, tc := range tcs {
+		t.Run(tc.name, func(t *testing.T) {
+			done := make(chan credentials.AuthInfo, 1)
+			lis := launchServerOnListenAddress(t, tlsServerHandshake, done, tc.address)
+			defer lis.Close()
+			lisAddr := lis.Addr().String()
+			clientAuthInfo := clientHandle(t, gRPCClientHandshake, lisAddr)
+			// wait until server sends serverAuthInfo or fails.
+			serverAuthInfo, ok := <-done
+			if !ok {
+				t.Fatalf("Error at server-side")
+			}
+			if !compare(clientAuthInfo, serverAuthInfo) {
+				t.Fatalf("c.ClientHandshake(_, %v, _) = %v, want %v.", lisAddr, clientAuthInfo, serverAuthInfo)
+			}
+		})
+	}
+}
+
+func (s) TestServerHandshakeReturnsAuthInfo(t *testing.T) {
+	done := make(chan credentials.AuthInfo, 1)
+	lis := launchServer(t, gRPCServerHandshake, done)
+	defer lis.Close()
+	clientAuthInfo := clientHandle(t, tlsClientHandshake, lis.Addr().String())
+	// wait until server sends serverAuthInfo or fails.
+	serverAuthInfo, ok := <-done
+	if !ok {
+		t.Fatalf("Error at server-side")
+	}
+	if !compare(clientAuthInfo, serverAuthInfo) {
+		t.Fatalf("ServerHandshake(_) = %v, want %v.", serverAuthInfo, clientAuthInfo)
+	}
+}
+
+func (s) TestServerAndClientHandshake(t *testing.T) {
+	done := make(chan credentials.AuthInfo, 1)
+	lis := launchServer(t, gRPCServerHandshake, done)
+	defer lis.Close()
+	clientAuthInfo := clientHandle(t, gRPCClientHandshake, lis.Addr().String())
+	// wait until server sends serverAuthInfo or fails.
+	serverAuthInfo, ok := <-done
+	if !ok {
+		t.Fatalf("Error at server-side")
+	}
+	if !compare(clientAuthInfo, serverAuthInfo) {
+		t.Fatalf("AuthInfo returned by server: %v and client: %v aren't same", serverAuthInfo, clientAuthInfo)
+	}
+}
+
+func compare(a1, a2 credentials.AuthInfo) bool {
+	if a1.AuthType() != a2.AuthType() {
+		return false
+	}
+	switch a1.AuthType() {
+	case "tls":
+		state1 := a1.(credentials.TLSInfo).State
+		state2 := a2.(credentials.TLSInfo).State
+		if state1.Version == state2.Version &&
+			state1.HandshakeComplete == state2.HandshakeComplete &&
+			state1.CipherSuite == state2.CipherSuite &&
+			state1.NegotiatedProtocol == state2.NegotiatedProtocol {
+			return true
+		}
+		return false
+	default:
+		return false
+	}
+}
+
+func launchServer(t *testing.T, hs serverHandshake, done chan credentials.AuthInfo) net.Listener {
+	return launchServerOnListenAddress(t, hs, done, "localhost:0")
+}
+
+func launchServerOnListenAddress(t *testing.T, hs serverHandshake, done chan credentials.AuthInfo, address string) net.Listener {
+	lis, err := net.Listen("tcp", address)
+	if err != nil {
+		if strings.Contains(err.Error(), "bind: cannot assign requested address") ||
+			strings.Contains(err.Error(), "socket: address family not supported by protocol") {
+			t.Skipf("no support for address %v", address)
+		}
+		t.Fatalf("Failed to listen: %v", err)
+	}
+	go serverHandle(t, hs, done, lis)
+	return lis
+}
+
+// Is run in a separate goroutine.
+func serverHandle(t *testing.T, hs serverHandshake, done chan credentials.AuthInfo, lis net.Listener) {
+	serverRawConn, err := lis.Accept()
+	if err != nil {
+		t.Errorf("Server failed to accept connection: %v", err)
+		close(done)
+		return
+	}
+	serverAuthInfo, err := hs(serverRawConn)
+	if err != nil {
+		t.Errorf("Server failed while handshake. Error: %v", err)
+		serverRawConn.Close()
+		close(done)
+		return
+	}
+	done <- serverAuthInfo
+}
+
+func clientHandle(t *testing.T, hs func(net.Conn, string) (credentials.AuthInfo, error), lisAddr string) credentials.AuthInfo {
+	conn, err := net.Dial("tcp", lisAddr)
+	if err != nil {
+		t.Fatalf("Client failed to connect to %s. Error: %v", lisAddr, err)
+	}
+	defer conn.Close()
+	clientAuthInfo, err := hs(conn, lisAddr)
+	if err != nil {
+		t.Fatalf("Error on client while handshake. Error: %v", err)
+	}
+	return clientAuthInfo
+}
+
+// Server handshake implementation in gRPC.
+func gRPCServerHandshake(conn net.Conn) (credentials.AuthInfo, error) {
+	serverTLS, err := NewServerTLSFromFileWithALPNDisabled(testdata.Path("x509/server1_cert.pem"), testdata.Path("x509/server1_key.pem"))
+	if err != nil {
+		return nil, err
+	}
+	_, serverAuthInfo, err := serverTLS.ServerHandshake(conn)
+	if err != nil {
+		return nil, err
+	}
+	return serverAuthInfo, nil
+}
+
+// Client handshake implementation in gRPC.
+func gRPCClientHandshake(conn net.Conn, lisAddr string) (credentials.AuthInfo, error) {
+	clientTLS := NewTLSWithALPNDisabled(&tls.Config{InsecureSkipVerify: true})
+	ctx, cancel := context.WithTimeout(context.Background(), defaultTestTimeout)
+	defer cancel()
+	_, authInfo, err := clientTLS.ClientHandshake(ctx, lisAddr, conn)
+	if err != nil {
+		return nil, err
+	}
+	return authInfo, nil
+}
+
+func tlsServerHandshake(conn net.Conn) (credentials.AuthInfo, error) {
+	cert, err := tls.LoadX509KeyPair(testdata.Path("x509/server1_cert.pem"), testdata.Path("x509/server1_key.pem"))
+	if err != nil {
+		return nil, err
+	}
+	serverTLSConfig := &tls.Config{Certificates: []tls.Certificate{cert}}
+	serverConn := tls.Server(conn, serverTLSConfig)
+	err = serverConn.Handshake()
+	if err != nil {
+		return nil, err
+	}
+	return credentials.TLSInfo{State: serverConn.ConnectionState(), CommonAuthInfo: credentials.CommonAuthInfo{SecurityLevel: credentials.PrivacyAndIntegrity}}, nil
+}
+
+func tlsClientHandshake(conn net.Conn, _ string) (credentials.AuthInfo, error) {
+	clientTLSConfig := &tls.Config{InsecureSkipVerify: true}
+	clientConn := tls.Client(conn, clientTLSConfig)
+	if err := clientConn.Handshake(); err != nil {
+		return nil, err
+	}
+	return credentials.TLSInfo{State: clientConn.ConnectionState(), CommonAuthInfo: credentials.CommonAuthInfo{SecurityLevel: credentials.PrivacyAndIntegrity}}, nil
+}

experimental/credentials/internal/spiffe.go

@@ -0,0 +1,75 @@
+/*
+ *
+ * Copyright 2025 gRPC authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ *
+ */
+
+// Package internal defines APIs for parsing SPIFFE ID.
+//
+// All APIs in this package are experimental.
+package internal
+
+import (
+	"crypto/tls"
+	"crypto/x509"
+	"net/url"
+
+	"google.golang.org/grpc/grpclog"
+)
+
+var logger = grpclog.Component("credentials")
+
+// SPIFFEIDFromState parses the SPIFFE ID from State. If the SPIFFE ID format
+// is invalid, return nil with warning.
+func SPIFFEIDFromState(state tls.ConnectionState) *url.URL {
+	if len(state.PeerCertificates) == 0 || len(state.PeerCertificates[0].URIs) == 0 {
+		return nil
+	}
+	return SPIFFEIDFromCert(state.PeerCertificates[0])
+}
+
+// SPIFFEIDFromCert parses the SPIFFE ID from x509.Certificate. If the SPIFFE
+// ID format is invalid, return nil with warning.
+func SPIFFEIDFromCert(cert *x509.Certificate) *url.URL {
+	if cert == nil || cert.URIs == nil {
+		return nil
+	}
+	var spiffeID *url.URL
+	for _, uri := range cert.URIs {
+		if uri == nil || uri.Scheme != "spiffe" || uri.Opaque != "" || (uri.User != nil && uri.User.Username() != "") {
+			continue
+		}
+		// From this point, we assume the uri is intended for a SPIFFE ID.
+		if len(uri.String()) > 2048 {
+			logger.Warning("invalid SPIFFE ID: total ID length larger than 2048 bytes")
+			return nil
+		}
+		if len(uri.Host) == 0 || len(uri.Path) == 0 {
+			logger.Warning("invalid SPIFFE ID: domain or workload ID is empty")
+			return nil
+		}
+		if len(uri.Host) > 255 {
+			logger.Warning("invalid SPIFFE ID: domain length larger than 255 characters")
+			return nil
+		}
+		// A valid SPIFFE certificate can only have exactly one URI SAN field.
+		if len(cert.URIs) > 1 {
+			logger.Warning("invalid SPIFFE ID: multiple URI SANs")
+			return nil
+		}
+		spiffeID = uri
+	}
+	return spiffeID
+}