// Copyright 2011 Google Inc. All rights reserved.
// Use of this source code is governed by the Apache 2.0
// license that can be found in the LICENSE file.
// Package urlfetch provides an http.RoundTripper implementation
// for fetching URLs via App Engine's urlfetch service.
package urlfetch // import "google.golang.org/appengine/urlfetch"
import (
"errors"
"fmt"
"io"
"io/ioutil"
"net/http"
"net/url"
"strconv"
"strings"
"time"
"github.com/golang/protobuf/proto"
"golang.org/x/net/context"
"google.golang.org/appengine/internal"
pb "google.golang.org/appengine/internal/urlfetch"
)
// Transport is an implementation of http.RoundTripper for
// App Engine. Users should generally create an http.Client using
// this transport and use the Client rather than using this transport
// directly.
type Transport struct {
Context context.Context
// Controls whether the application checks the validity of SSL certificates
// over HTTPS connections. A value of false (the default) instructs the
// application to send a request to the server only if the certificate is
// valid and signed by a trusted certificate authority (CA), and also
// includes a hostname that matches the certificate. A value of true
// instructs the application to perform no certificate validation.
AllowInvalidServerCertificate bool
}
// Verify statically that *Transport implements http.RoundTripper.
var _ http.RoundTripper = (*Transport)(nil)
// Client returns an *http.Client using a default urlfetch Transport. This
// client will have the default deadline of 5 seconds, and will check the
// validity of SSL certificates.
//
// Any deadline of the provided context will be used for requests through this client;
// if the client does not have a deadline then a 5 second default is used.
func Client(ctx context.Context) *http.Client {
return &http.Client{
Transport: &Transport{
Context: ctx,
},
}
}
type bodyReader struct {
content []byte
truncated bool
closed bool
}
// ErrTruncatedBody is the error returned after the final Read() from a
// response's Body if the body has been truncated by App Engine's proxy.
var ErrTruncatedBody = errors.New("urlfetch: truncated body")
func statusCodeToText(code int) string {
if t := http.StatusText(code); t != "" {
return t
}
return strconv.Itoa(code)
}
func (br *bodyReader) Read(p []byte) (n int, err error) {
if br.closed {
if br.truncated {
return 0, ErrTruncatedBody
}
return 0, io.EOF
}
n = copy(p, br.content)
if n > 0 {
br.content = br.content[n:]
return
}
if br.truncated {
br.closed = true
return 0, ErrTruncatedBody
}
return 0, io.EOF
}
func (br *bodyReader) Close() error {
br.closed = true
br.content = nil
return nil
}
// A map of the URL Fetch-accepted methods that take a request body.
var methodAcceptsRequestBody = map[string]bool{
"POST": true,
"PUT": true,
"PATCH": true,
}
// urlString returns a valid string given a URL. This function is necessary because
// the String method of URL doesn't correctly handle URLs with non-empty Opaque values.
// See http://code.google.com/p/go/issues/detail?id=4860.
func urlString(u *url.URL) string {
if u.Opaque == "" || strings.HasPrefix(u.Opaque, "//") {
return u.String()
}
aux := *u
aux.Opaque = "//" + aux.Host + aux.Opaque
return aux.String()
}
// RoundTrip issues a single HTTP request and returns its response. Per the
// http.RoundTripper interface, RoundTrip only returns an error if there
// was an unsupported request or the URL Fetch proxy fails.
// Note that HTTP response codes such as 5xx, 403, 404, etc are not
// errors as far as the transport is concerned and will be returned
// with err set to nil.
func (t *Transport) RoundTrip(req *http.Request) (res *http.Response, err error) {
methNum, ok := pb.URLFetchRequest_RequestMethod_value[req.Method]
if !ok {
return nil, fmt.Errorf("urlfetch: unsupported HTTP method %q", req.Method)
}
method := pb.URLFetchRequest_RequestMethod(methNum)
freq := &pb.URLFetchRequest{
Method: &method,
Url: proto.String(urlString(req.URL)),
FollowRedirects: proto.Bool(false), // http.Client's responsibility
MustValidateServerCertificate: proto.Bool(!t.AllowInvalidServerCertificate),
}
if deadline, ok := t.Context.Deadline(); ok {
freq.Deadline = proto.Float64(deadline.Sub(time.Now()).Seconds())
}
for k, vals := range req.Header {
for _, val := range vals {
freq.Header = append(freq.Header, &pb.URLFetchRequest_Header{
Key: proto.String(k),
Value: proto.String(val),
})
}
}
if methodAcceptsRequestBody[req.Method] && req.Body != nil {
// Avoid a []byte copy if req.Body has a Bytes method.
switch b := req.Body.(type) {
case interface {
Bytes() []byte
}:
freq.Payload = b.Bytes()
default:
freq.Payload, err = ioutil.ReadAll(req.Body)
if err != nil {
return nil, err
}
}
}
fres := &pb.URLFetchResponse{}
if err := internal.Call(t.Context, "urlfetch", "Fetch", freq, fres); err != nil {
return nil, err
}
res = &http.Response{}
res.StatusCode = int(*fres.StatusCode)
res.Status = fmt.Sprintf("%d %s", res.StatusCode, statusCodeToText(res.StatusCode))
res.Header = make(http.Header)
res.Request = req
// Faked:
res.ProtoMajor = 1
res.ProtoMinor = 1
res.Proto = "HTTP/1.1"
res.Close = true
for _, h := range fres.Header {
hkey := http.CanonicalHeaderKey(*h.Key)
hval := *h.Value
if hkey == "Content-Length" {
// Will get filled in below for all but HEAD requests.
if req.Method == "HEAD" {
res.ContentLength, _ = strconv.ParseInt(hval, 10, 64)
}
continue
}
res.Header.Add(hkey, hval)
}
if req.Method != "HEAD" {
res.ContentLength = int64(len(fres.Content))
}
truncated := fres.GetContentWasTruncated()
res.Body = &bodyReader{content: fres.Content, truncated: truncated}
return
}
func init() {
internal.RegisterErrorCodeMap("urlfetch", pb.URLFetchServiceError_ErrorCode_name)
internal.RegisterTimeoutErrorCode("urlfetch", int32(pb.URLFetchServiceError_DEADLINE_EXCEEDED))
}
