Update github.com/xenolf/lego to 0.4.1

vendor/github.com/Azure/go-autorest/autorest/sender.go

@@ -1,12 +1,11 @@
 package autorest
 
 import (
-	"bytes"
 	"fmt"
-	"io/ioutil"
 	"log"
 	"math"
 	"net/http"
+	"strconv"
 	"time"
 )
 
@@ -175,8 +174,13 @@ func DoPollForStatusCodes(duration time.Duration, delay time.Duration, codes ...
 func DoRetryForAttempts(attempts int, backoff time.Duration) SendDecorator {
 	return func(s Sender) Sender {
 		return SenderFunc(func(r *http.Request) (resp *http.Response, err error) {
+			rr := NewRetriableRequest(r)
 			for attempt := 0; attempt < attempts; attempt++ {
-				resp, err = s.Do(r)
+				err = rr.Prepare()
+				if err != nil {
+					return resp, err
+				}
+				resp, err = s.Do(rr.Request())
 				if err == nil {
 					return resp, err
 				}
@@ -194,29 +198,43 @@ func DoRetryForAttempts(attempts int, backoff time.Duration) SendDecorator {
 func DoRetryForStatusCodes(attempts int, backoff time.Duration, codes ...int) SendDecorator {
 	return func(s Sender) Sender {
 		return SenderFunc(func(r *http.Request) (resp *http.Response, err error) {
-			b := []byte{}
-			if r.Body != nil {
-				b, err = ioutil.ReadAll(r.Body)
-				if err != nil {
-					return resp, err
-				}
-			}
-
+			rr := NewRetriableRequest(r)
 			// Increment to add the first call (attempts denotes number of retries)
 			attempts++
 			for attempt := 0; attempt < attempts; attempt++ {
-				r.Body = ioutil.NopCloser(bytes.NewBuffer(b))
-				resp, err = s.Do(r)
+				err = rr.Prepare()
+				if err != nil {
+					return resp, err
+				}
+				resp, err = s.Do(rr.Request())
 				if err != nil || !ResponseHasStatusCode(resp, codes...) {
 					return resp, err
 				}
-				DelayForBackoff(backoff, attempt, r.Cancel)
+				delayed := DelayWithRetryAfter(resp, r.Cancel)
+				if !delayed {
+					DelayForBackoff(backoff, attempt, r.Cancel)
+				}
 			}
 			return resp, err
 		})
 	}
 }
 
+// DelayWithRetryAfter invokes time.After for the duration specified in the "Retry-After" header in
+// responses with status code 429
+func DelayWithRetryAfter(resp *http.Response, cancel <-chan struct{}) bool {
+	retryAfter, _ := strconv.Atoi(resp.Header.Get("Retry-After"))
+	if resp.StatusCode == http.StatusTooManyRequests && retryAfter > 0 {
+		select {
+		case <-time.After(time.Duration(retryAfter) * time.Second):
+			return true
+		case <-cancel:
+			return false
+		}
+	}
+	return false
+}
+
 // DoRetryForDuration returns a SendDecorator that retries the request until the total time is equal
 // to or greater than the specified duration, exponentially backing off between requests using the
 // supplied backoff time.Duration (which may be zero). Retrying may be canceled by closing the
@@ -224,9 +242,14 @@ func DoRetryForStatusCodes(attempts int, backoff time.Duration, codes ...int) Se
 func DoRetryForDuration(d time.Duration, backoff time.Duration) SendDecorator {
 	return func(s Sender) Sender {
 		return SenderFunc(func(r *http.Request) (resp *http.Response, err error) {
+			rr := NewRetriableRequest(r)
 			end := time.Now().Add(d)
 			for attempt := 0; time.Now().Before(end); attempt++ {
-				resp, err = s.Do(r)
+				err = rr.Prepare()
+				if err != nil {
+					return resp, err
+				}
+				resp, err = s.Do(rr.Request())
 				if err == nil {
 					return resp, err
 				}