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// Copyright 2015 Google Inc. All Rights Reserved.
//
// 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 transport supports network connections to HTTP and GRPC servers.
// This package is not intended for use by end developers. Use the
// google.golang.org/api/option package to configure API clients.
package transport
import (
"errors"
"fmt"
"io/ioutil"
"net/http"
"golang.org/x/net/context"
"golang.org/x/oauth2"
"golang.org/x/oauth2/google"
"google.golang.org/grpc"
"google.golang.org/grpc/credentials"
"google.golang.org/grpc/credentials/oauth"
gtransport "google.golang.org/api/googleapi/transport"
"google.golang.org/api/internal"
"google.golang.org/api/option"
)
// NewHTTPClient returns an HTTP client for use communicating with a Google cloud
// service, configured with the given ClientOptions. It also returns the endpoint
// for the service as specified in the options.
func NewHTTPClient(ctx context.Context, opts ...option.ClientOption) (*http.Client, string, error) {
var o internal.DialSettings
for _, opt := range opts {
opt.Apply(&o)
}
if o.GRPCConn != nil {
return nil, "", errors.New("unsupported gRPC connection specified")
}
// TODO(cbro): consider injecting the User-Agent even if an explicit HTTP client is provided?
if o.HTTPClient != nil {
return o.HTTPClient, o.Endpoint, nil
}
if o.APIKey != "" {
hc := &http.Client{
Transport: >ransport.APIKey{
Key: o.APIKey,
Transport: userAgentTransport{
base: baseTransport(ctx),
userAgent: o.UserAgent,
},
},
}
return hc, o.Endpoint, nil
}
if o.ServiceAccountJSONFilename != "" {
ts, err := serviceAcctTokenSource(ctx, o.ServiceAccountJSONFilename, o.Scopes...)
if err != nil {
return nil, "", err
}
o.TokenSource = ts
}
if o.TokenSource == nil {
var err error
o.TokenSource, err = google.DefaultTokenSource(ctx, o.Scopes...)
if err != nil {
return nil, "", fmt.Errorf("google.DefaultTokenSource: %v", err)
}
}
hc := &http.Client{
Transport: &oauth2.Transport{
Source: o.TokenSource,
Base: userAgentTransport{
base: baseTransport(ctx),
userAgent: o.UserAgent,
},
},
}
return hc, o.Endpoint, nil
}
type userAgentTransport struct {
userAgent string
base http.RoundTripper
}
func (t userAgentTransport) RoundTrip(req *http.Request) (*http.Response, error) {
rt := t.base
if rt == nil {
return nil, errors.New("transport: no Transport specified")
}
if t.userAgent == "" {
return rt.RoundTrip(req)
}
newReq := *req
newReq.Header = make(http.Header)
for k, vv := range req.Header {
newReq.Header[k] = vv
}
// TODO(cbro): append to existing User-Agent header?
newReq.Header["User-Agent"] = []string{t.userAgent}
return rt.RoundTrip(&newReq)
}
// Set at init time by dial_appengine.go. If nil, we're not on App Engine.
var appengineDialerHook func(context.Context) grpc.DialOption
var appengineUrlfetchHook func(context.Context) http.RoundTripper
// baseTransport returns the base HTTP transport.
// On App Engine, this is urlfetch.Transport, otherwise it's http.DefaultTransport.
func baseTransport(ctx context.Context) http.RoundTripper {
if appengineUrlfetchHook != nil {
return appengineUrlfetchHook(ctx)
}
return http.DefaultTransport
}
// DialGRPC returns a GRPC connection for use communicating with a Google cloud
// service, configured with the given ClientOptions.
func DialGRPC(ctx context.Context, opts ...option.ClientOption) (*grpc.ClientConn, error) {
var o internal.DialSettings
for _, opt := range opts {
opt.Apply(&o)
}
if o.HTTPClient != nil {
return nil, errors.New("unsupported HTTP client specified")
}
if o.GRPCConn != nil {
return o.GRPCConn, nil
}
if o.ServiceAccountJSONFilename != "" {
ts, err := serviceAcctTokenSource(ctx, o.ServiceAccountJSONFilename, o.Scopes...)
if err != nil {
return nil, err
}
o.TokenSource = ts
}
if o.TokenSource == nil {
var err error
o.TokenSource, err = google.DefaultTokenSource(ctx, o.Scopes...)
if err != nil {
return nil, fmt.Errorf("google.DefaultTokenSource: %v", err)
}
}
grpcOpts := []grpc.DialOption{
grpc.WithPerRPCCredentials(oauth.TokenSource{o.TokenSource}),
grpc.WithTransportCredentials(credentials.NewClientTLSFromCert(nil, "")),
}
if appengineDialerHook != nil {
// Use the Socket API on App Engine.
grpcOpts = append(grpcOpts, appengineDialerHook(ctx))
}
grpcOpts = append(grpcOpts, o.GRPCDialOpts...)
if o.UserAgent != "" {
grpcOpts = append(grpcOpts, grpc.WithUserAgent(o.UserAgent))
}
return grpc.DialContext(ctx, o.Endpoint, grpcOpts...)
}
func serviceAcctTokenSource(ctx context.Context, filename string, scope ...string) (oauth2.TokenSource, error) {
data, err := ioutil.ReadFile(filename)
if err != nil {
return nil, fmt.Errorf("cannot read service account file: %v", err)
}
cfg, err := google.JWTConfigFromJSON(data, scope...)
if err != nil {
return nil, fmt.Errorf("google.JWTConfigFromJSON: %v", err)
}
return cfg.TokenSource(ctx), nil
}
// DialGRPCInsecure returns an insecure GRPC connection for use communicating
// with fake or mock Google cloud service implementations, such as emulators.
// The connection is configured with the given ClientOptions.
func DialGRPCInsecure(ctx context.Context, opts ...option.ClientOption) (*grpc.ClientConn, error) {
var o internal.DialSettings
for _, opt := range opts {
opt.Apply(&o)
}
if o.HTTPClient != nil {
return nil, errors.New("unsupported HTTP client specified")
}
if o.GRPCConn != nil {
return o.GRPCConn, nil
}
grpcOpts := []grpc.DialOption{grpc.WithInsecure()}
grpcOpts = append(grpcOpts, o.GRPCDialOpts...)
if o.UserAgent != "" {
grpcOpts = append(grpcOpts, grpc.WithUserAgent(o.UserAgent))
}
return grpc.DialContext(ctx, o.Endpoint, grpcOpts...)
}
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