/
debugging_round_tripper.go
129 lines (108 loc) · 3.13 KB
/
debugging_round_tripper.go
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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 httputil
import (
"bytes"
"fmt"
"io/ioutil"
"log"
"net/http"
"net/http/httputil"
)
// An interface for transports that support the signature of
// http.Transport.CancelRequest.
type CancellableRoundTripper interface {
http.RoundTripper
CancelRequest(*http.Request)
}
// Wrap the supplied round tripper in a layer that dumps information about HTTP
// requests. unmodified.
func DebuggingRoundTripper(
in CancellableRoundTripper,
logger *log.Logger) (out CancellableRoundTripper) {
out = &debuggingRoundTripper{
wrapped: in,
logger: logger,
}
return
}
////////////////////////////////////////////////////////////////////////
// Helpers
////////////////////////////////////////////////////////////////////////
// Ensure that the supplied request has a correct ContentLength field set.
func fillInContentLength(req *http.Request) (err error) {
body := req.Body
if body == nil {
req.ContentLength = 0
return
}
// Make a copy.
contents, err := ioutil.ReadAll(req.Body)
if err != nil {
err = fmt.Errorf("ReadAll: %v", err)
return
}
req.Body.Close()
// Fill in the content length and restore the body.
req.ContentLength = int64(len(contents))
req.Body = ioutil.NopCloser(bytes.NewReader(contents))
return
}
////////////////////////////////////////////////////////////////////////
// debuggingRoundTripper
////////////////////////////////////////////////////////////////////////
type debuggingRoundTripper struct {
wrapped CancellableRoundTripper
logger *log.Logger
}
func (t *debuggingRoundTripper) RoundTrip(
req *http.Request) (resp *http.Response, err error) {
// Ensure that the request has a ContentLength field, so that it doesn't need
// to be transmitted with chunked encoding. This improves debugging output.
err = fillInContentLength(req)
if err != nil {
err = fmt.Errorf("fillInContentLength: %v", err)
return
}
// Dump the request.
{
var dumped []byte
dumped, err = httputil.DumpRequestOut(req, true)
if err != nil {
err = fmt.Errorf("DumpRequestOut: %v", err)
return
}
t.logger.Printf("========== REQUEST:\n%s", dumped)
}
// Execute the request.
resp, err = t.wrapped.RoundTrip(req)
if err != nil {
return
}
// Dump the response.
{
var dumped []byte
dumped, err = httputil.DumpResponse(resp, true)
if err != nil {
err = fmt.Errorf("DumpResponse: %v", err)
return
}
t.logger.Printf("========== RESPONSE:\n%s", dumped)
t.logger.Println("====================")
}
return
}
func (t *debuggingRoundTripper) CancelRequest(req *http.Request) {
t.wrapped.CancelRequest(req)
}