99 lines
2.9 KiB
Go
99 lines
2.9 KiB
Go
/*
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*
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* Copyright 2021 Google LLC
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* https://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*
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*/
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// Package service is a utility for calling the S2A handshaker service.
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package service
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import (
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"context"
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"net"
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"os"
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"strings"
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"sync"
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"time"
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"google.golang.org/appengine"
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"google.golang.org/appengine/socket"
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grpc "google.golang.org/grpc"
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"google.golang.org/grpc/grpclog"
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)
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// An environment variable, if true, opportunistically use AppEngine-specific dialer to call S2A.
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const enableAppEngineDialerEnv = "S2A_ENABLE_APP_ENGINE_DIALER"
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var (
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// appEngineDialerHook is an AppEngine-specific dial option that is set
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// during init time. If nil, then the application is not running on Google
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// AppEngine.
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appEngineDialerHook func(context.Context) grpc.DialOption
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// mu guards hsConnMap and hsDialer.
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mu sync.Mutex
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// hsConnMap represents a mapping from an S2A handshaker service address
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// to a corresponding connection to an S2A handshaker service instance.
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hsConnMap = make(map[string]*grpc.ClientConn)
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// hsDialer will be reassigned in tests.
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hsDialer = grpc.Dial
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)
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func init() {
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if !appengine.IsAppEngine() && !appengine.IsDevAppServer() {
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return
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}
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appEngineDialerHook = func(ctx context.Context) grpc.DialOption {
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return grpc.WithDialer(func(addr string, timeout time.Duration) (net.Conn, error) {
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return socket.DialTimeout(ctx, "tcp", addr, timeout)
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})
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}
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}
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// Dial dials the S2A handshaker service. If a connection has already been
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// established, this function returns it. Otherwise, a new connection is
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// created.
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func Dial(handshakerServiceAddress string) (*grpc.ClientConn, error) {
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mu.Lock()
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defer mu.Unlock()
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hsConn, ok := hsConnMap[handshakerServiceAddress]
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if !ok {
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// Create a new connection to the S2A handshaker service. Note that
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// this connection stays open until the application is closed.
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grpcOpts := []grpc.DialOption{
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grpc.WithInsecure(),
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}
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if enableAppEngineDialer() && appEngineDialerHook != nil {
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if grpclog.V(1) {
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grpclog.Info("Using AppEngine-specific dialer to talk to S2A.")
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}
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grpcOpts = append(grpcOpts, appEngineDialerHook(context.Background()))
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}
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var err error
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hsConn, err = hsDialer(handshakerServiceAddress, grpcOpts...)
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if err != nil {
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return nil, err
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}
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hsConnMap[handshakerServiceAddress] = hsConn
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}
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return hsConn, nil
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}
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func enableAppEngineDialer() bool {
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if strings.ToLower(os.Getenv(enableAppEngineDialerEnv)) == "true" {
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return true
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}
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return false
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}
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