Simplified ALPN API for server side

Summary:
Simplify the API so that it's more concise and easier for the end user.

ALPN enablement before this API: D64625041
ALPN enablement after this API: D65916844

Reviewed By: awalterschulze

Differential Revision: D65275022

fbshipit-source-id: 85d88fac5b0581d5e244b770375e990997071702

thrift/lib/go/thrift/server_options.go

@@ -18,6 +18,7 @@ package thrift
 
 import (
 	"context"
+	"crypto/tls"
 	"log"
 	"net"
 	"os"
@@ -120,3 +121,24 @@ func WithProcessorStats(processorStats map[string]*stats.TimingSeries) ServerOpt
 		server.processorStats = processorStats
 	}
 }
+
+// WithALPNHeader adds the ALPN value "thrift" to the provided tls.Config
+func WithALPNHeader() func(*tls.Config) {
+	return func(tlsConfig *tls.Config) {
+		tlsConfig.NextProtos = []string{"thrift"}
+	}
+}
+
+// WithALPNRocket adds the ALPN value "rs" to the provided tls.Config
+func WithALPNRocket() func(*tls.Config) {
+	return func(tlsConfig *tls.Config) {
+		tlsConfig.NextProtos = []string{"rs"}
+	}
+}
+
+// WithALPNUpgradeToRocket adds the ALPN value "rs" and "thrift" to the provided tls.Config
+func WithALPNUpgradeToRocket() func(*tls.Config) {
+	return func(tlsConfig *tls.Config) {
+		tlsConfig.NextProtos = []string{"rs" /* preferred */, "thrift" /* fallback */}
+	}
+}

thrift/lib/go/thrift/server_options_test.go

@@ -0,0 +1,45 @@
+/*
+ * Copyright (c) Meta Platforms, Inc. and affiliates.
+ *
+ * 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 thrift
+
+import (
+	"crypto/tls"
+	"reflect"
+	"testing"
+)
+
+func TestListenerALPNOptions(t *testing.T) {
+	testCases := []struct {
+		name               string
+		option             func(*tls.Config)
+		expectedNextProtos []string
+	}{
+		{"Header", WithALPNHeader(), []string{"thrift"}},
+		{"Rocket", WithALPNRocket(), []string{"rs"}},
+		{"UpgradeToRocket", WithALPNUpgradeToRocket(), []string{"rs", "thrift"}},
+	}
+
+	for _, tc := range testCases {
+		t.Run(tc.name, func(t *testing.T) {
+			tlsConfig := &tls.Config{}
+			tc.option(tlsConfig)
+			if !reflect.DeepEqual(tlsConfig.NextProtos, tc.expectedNextProtos) {
+				t.Fatalf("unexpected NextProtos: %v (expected), %v (actual)", tc.expectedNextProtos, tlsConfig.NextProtos)
+			}
+		})
+	}
+}