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// Copyright 2015 Google LLC
//
// 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/http supports network connections to HTTP servers.
// This package is not intended for use by end developers. Use the
// google.golang.org/api/option package to configure API clients.
package http
import (
"errors"
"net/http"
"golang.org/x/net/context"
"golang.org/x/oauth2"
"google.golang.org/api/googleapi/transport"
"google.golang.org/api/internal"
"google.golang.org/api/option"
)
// NewClient 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 NewClient(ctx context.Context, opts ...option.ClientOption) (*http.Client, string, error) {
settings, err := newSettings(opts)
if err != nil {
return nil, "", err
}
// TODO(cbro): consider injecting the User-Agent even if an explicit HTTP client is provided?
if settings.HTTPClient != nil {
return settings.HTTPClient, settings.Endpoint, nil
}
trans, err := newTransport(ctx, defaultBaseTransport(ctx), settings)
if err != nil {
return nil, "", err
}
return &http.Client{Transport: trans}, settings.Endpoint, nil
}
// NewTransport creates an http.RoundTripper for use communicating with a Google
// cloud service, configured with the given ClientOptions. Its RoundTrip method delegates to base.
func NewTransport(ctx context.Context, base http.RoundTripper, opts ...option.ClientOption) (http.RoundTripper, error) {
settings, err := newSettings(opts)
if err != nil {
return nil, err
}
if settings.HTTPClient != nil {
return nil, errors.New("transport/http: WithHTTPClient passed to NewTransport")
}
return newTransport(ctx, base, settings)
}
func newTransport(ctx context.Context, base http.RoundTripper, settings *internal.DialSettings) (http.RoundTripper, error) {
trans := base
trans = userAgentTransport{
base: trans,
userAgent: settings.UserAgent,
}
trans = addOCTransport(trans)
switch {
case settings.NoAuth:
// Do nothing.
case settings.APIKey != "":
trans = &transport.APIKey{
Transport: trans,
Key: settings.APIKey,
}
default:
creds, err := internal.Creds(ctx, settings)
if err != nil {
return nil, err
}
trans = &oauth2.Transport{
Base: trans,
Source: creds.TokenSource,
}
}
return trans, nil
}
func newSettings(opts []option.ClientOption) (*internal.DialSettings, error) {
var o internal.DialSettings
for _, opt := range opts {
opt.Apply(&o)
}
if err := o.Validate(); err != nil {
return nil, err
}
if o.GRPCConn != nil {
return nil, errors.New("unsupported gRPC connection specified")
}
return &o, 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 appengineUrlfetchHook func(context.Context) http.RoundTripper
// defaultBaseTransport returns the base HTTP transport.
// On App Engine, this is urlfetch.Transport, otherwise it's http.DefaultTransport.
func defaultBaseTransport(ctx context.Context) http.RoundTripper {
if appengineUrlfetchHook != nil {
return appengineUrlfetchHook(ctx)
}
return http.DefaultTransport
}
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