Restore the Response and Request when read from Transport

Since the Request.Body and Response.Body are read from any transport.RoundTrip,
it is needed to restore them before reusing it again;
otherwise, the Request.Body or Response.Body won't be readable.

Signed-off-by: David Pordomingo <[email protected]>

examples/cmd/logtransport.go

@@ -1,12 +1,12 @@
 package main
 
 import (
-	"bytes"
-	"io/ioutil"
 	"net/http"
 	"time"
 
 	"gopkg.in/src-d/go-log.v1"
+
+	"github.com/src-d/metadata-retrieval/utils"
 )
 
 func setLogTransport(client *http.Client, logger log.Logger) {
@@ -21,15 +21,23 @@ type logTransport struct {
 func (t *logTransport) RoundTrip(r *http.Request) (*http.Response, error) {
 	t0 := time.Now()
 
-	reqBody, _ := ioutil.ReadAll(r.Body)
-	r.Body = ioutil.NopCloser(bytes.NewBuffer(reqBody))
-
+	// Since the underlaying Transport.RoundTrip might consume the Request, and it's also needed later to log the process,
+	// it is needed to make an snapshot of the Request.Body in advance; otherwise, its will be no longer accessible.
+	bakupReqBody := utils.BackupRequestBody(r)
 	resp, err := t.T.RoundTrip(r)
+	restoreRequestBody(r, bakupReqBody)
+
+	// Since the outter Transport.RoundTrip calling this one might also consume the Request, and it is also needed here to log
+	// the process, it will be done over a snapshot of the Request.Body; otherwise, its will be no longer accessible by outer Transports.
+	reqBody, _ := utils.ReadRequestAndRestore(r)
+
 	if err != nil {
 		return resp, err
 	}
 
-	respBody, err := ioutil.ReadAll(resp.Body)
+	// Since the Response has been read, it is needed to restore it
+	// before reusing it; otherwise, its body will be unreadable again in other Transports.
+	respBody, err := utils.ReadResponseAndRestore(resp)
 	if err != nil {
 		return resp, err
 	}
@@ -38,7 +46,5 @@ func (t *logTransport) RoundTrip(r *http.Request) (*http.Response, error) {
 		log.Fields{"elapsed": time.Since(t0), "response-code": resp.StatusCode, "url": r.URL, "request-body": string(reqBody), "response-body": string(respBody)},
 	).Debugf("HTTP response")
 
-	resp.Body = ioutil.NopCloser(bytes.NewBuffer(respBody))
-
 	return resp, err
 }