1// Copyright 2016 The Go Authors. All rights reserved. 2// Use of this source code is governed by a BSD-style 3// license that can be found in the LICENSE file. 4 5package gensupport 6 7import ( 8 "errors" 9 "net/http" 10 11 "golang.org/x/net/context" 12 "golang.org/x/net/context/ctxhttp" 13) 14 15// Hook is the type of a function that is called once before each HTTP request 16// that is sent by a generated API. It returns a function that is called after 17// the request returns. 18// Hooks are not called if the context is nil. 19type Hook func(ctx context.Context, req *http.Request) func(resp *http.Response) 20 21var hooks []Hook 22 23// RegisterHook registers a Hook to be called before each HTTP request by a 24// generated API. Hooks are called in the order they are registered. Each 25// hook can return a function; if it is non-nil, it is called after the HTTP 26// request returns. These functions are called in the reverse order. 27// RegisterHook should not be called concurrently with itself or SendRequest. 28func RegisterHook(h Hook) { 29 hooks = append(hooks, h) 30} 31 32// SendRequest sends a single HTTP request using the given client. 33// If ctx is non-nil, it calls all hooks, then sends the request with 34// ctxhttp.Do, then calls any functions returned by the hooks in reverse order. 35func SendRequest(ctx context.Context, client *http.Client, req *http.Request) (*http.Response, error) { 36 // Disallow Accept-Encoding because it interferes with the automatic gzip handling 37 // done by the default http.Transport. See https://github.com/google/google-api-go-client/issues/219. 38 if _, ok := req.Header["Accept-Encoding"]; ok { 39 return nil, errors.New("google api: custom Accept-Encoding headers not allowed") 40 } 41 if ctx == nil { 42 return client.Do(req) 43 } 44 // Call hooks in order of registration, store returned funcs. 45 post := make([]func(resp *http.Response), len(hooks)) 46 for i, h := range hooks { 47 fn := h(ctx, req) 48 post[i] = fn 49 } 50 51 // Send request. 52 resp, err := ctxhttp.Do(ctx, client, req) 53 54 // Call returned funcs in reverse order. 55 for i := len(post) - 1; i >= 0; i-- { 56 if fn := post[i]; fn != nil { 57 fn(resp) 58 } 59 } 60 return resp, err 61} 62