private/default: Add support for 1digit RFC822 datetime day in Attemp…

…tClockSkewHandler (#560)

Fixes the SDK's behavior to parse unexpected HTTP Date header received that was formated with single digit day of the month instead of two digit RFC822 datetime like defined in RFC 2616. This should prevent log messages about unable to compute clock skew.

Fixes #556

CHANGELOG_PENDING.md

@@ -9,4 +9,7 @@ SDK Enhancements
 
 SDK Bugs
 ---
-`service/s3`: Fix S3 client behavior wrt 200 OK response with empty payload
+* `aws/defaults`: Fix handling of unexpected Date response header value ([#](https://github.com/aws/aws-sdk-go-v2/pull/560))
+  * Fixes the SDK's behavior to parse unexpected HTTP Date header received that was formated with single digit day of the month instead of two digit RFC822 datetime like defined in RFC 2616. This should prevent log messages about unable to compute clock skew.
+  * Fixes [#556](https://github.com/aws/aws-sdk-go-v2/issues/556)
+* `service/s3`: Fix S3 client behavior wrt 200 OK response with empty payload

aws/defaults/handlers.go

@@ -15,6 +15,7 @@ import (
 	"github.com/aws/aws-sdk-go-v2/aws"
 	"github.com/aws/aws-sdk-go-v2/aws/awserr"
 	"github.com/aws/aws-sdk-go-v2/internal/sdk"
+	"github.com/aws/aws-sdk-go-v2/private/protocol"
 )
 
 // Interface for matching types which also have a Len method.
@@ -304,6 +305,12 @@ var AttemptClockSkewHandler = aws.NamedHandler{
 		}
 
 		respDate, err := http.ParseTime(respDateHeader)
+		if err != nil {
+			// Fallback trying the SDK's RFC 822 datetime format parsing which handles 1digit formatted
+			// day of month pattern. RFC 2616 states the RFC 822 datetime muse use 2digit days, but some
+			// APIs may respond with the incorrect format.
+			respDate, err = protocol.ParseTime(protocol.RFC822TimeFormatName, respDateHeader)
+		}
 		if err != nil {
 			if r.Config.Logger != nil {
 				r.Config.Logger.Log(fmt.Sprintf("ERROR: unable to determine clock skew for %s/%s API response, invalid Date header value, %v",

aws/defaults/handlers_test.go

@@ -494,6 +494,18 @@ func TestAttemptClockSkewHandler(t *testing.T) {
 				},
 			},
 		},
+		"RFC822 1digit day time format support": {
+			Req: &aws.Request{
+				HTTPResponse: &http.Response{
+					StatusCode: 200,
+					Header: http.Header{
+						"Date": []string{"Thu, 5 Mar 2020 22:25:15 GMT"},
+					},
+				},
+				ResponseAt: time.Date(2020, 3, 5, 22, 25, 17, 0, time.UTC),
+			},
+			Expect: []time.Duration{-2 * time.Second},
+		},
 		"first date response": {
 			Req: &aws.Request{
 				HTTPResponse: &http.Response{