1 /*
2 *
3 * Copyright 2021 Google LLC
4 *
5 * Licensed under the Apache License, Version 2.0 (the "License");
6 * you may not use this file except in compliance with the License.
7 * You may obtain a copy of the License at
8 *
9 * https://www.apache.org/licenses/LICENSE-2.0
10 *
11 * Unless required by applicable law or agreed to in writing, software
12 * distributed under the License is distributed on an "AS IS" BASIS,
13 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
14 * See the License for the specific language governing permissions and
15 * limitations under the License.
16 *
17 */
18 19 // Package service is a utility for calling the S2A handshaker service.
20 package service
21 22 import (
23 "context"
24 "sync"
25 26 grpc "google.golang.org/grpc"
27 "google.golang.org/grpc/credentials"
28 "google.golang.org/grpc/credentials/insecure"
29 )
30 31 var (
32 // mu guards hsConnMap and hsDialer.
33 mu sync.Mutex
34 // hsConnMap represents a mapping from an S2A handshaker service address
35 // to a corresponding connection to an S2A handshaker service instance.
36 hsConnMap = make(map[string]*grpc.ClientConn)
37 // hsDialer will be reassigned in tests.
38 hsDialer = grpc.DialContext
39 )
40 41 // Dial dials the S2A handshaker service. If a connection has already been
42 // established, this function returns it. Otherwise, a new connection is
43 // created.
44 func Dial(ctx context.Context, handshakerServiceAddress string, transportCreds credentials.TransportCredentials) (*grpc.ClientConn, error) {
45 mu.Lock()
46 defer mu.Unlock()
47 48 hsConn, ok := hsConnMap[handshakerServiceAddress]
49 if !ok {
50 // Create a new connection to the S2A handshaker service. Note that
51 // this connection stays open until the application is closed.
52 var grpcOpts []grpc.DialOption
53 if transportCreds != nil {
54 grpcOpts = append(grpcOpts, grpc.WithTransportCredentials(transportCreds))
55 } else {
56 grpcOpts = append(grpcOpts, grpc.WithTransportCredentials(insecure.NewCredentials()))
57 }
58 var err error
59 hsConn, err = hsDialer(ctx, handshakerServiceAddress, grpcOpts...)
60 if err != nil {
61 return nil, err
62 }
63 hsConnMap[handshakerServiceAddress] = hsConn
64 }
65 return hsConn, nil
66 }
67