From 94635782522fcdeeb992ef3c2ab8629f0b70f849 Mon Sep 17 00:00:00 2001
From: Jason Del Ponte <961963+jasdel@users.noreply.github.com>
Date: Tue, 25 Jan 2022 13:05:51 -0800
Subject: [PATCH] aws/config: Update Request Send to always ensure HTTPResponse
 is not nil

Updates SDK Request.Send to always ensure HTTPResponse member is not
nil, and its Header and Body fields are not nil as well.

Fixes #4211
---
 CHANGELOG_PENDING.md        |  2 ++
 aws/request/request.go      |  9 +++++++++
 aws/request/request_test.go | 31 +++++++++++++++++++++++++++++++
 3 files changed, 42 insertions(+)

diff --git a/CHANGELOG_PENDING.md b/CHANGELOG_PENDING.md
index 8a1927a39c..d5e775f28b 100644
--- a/CHANGELOG_PENDING.md
+++ b/CHANGELOG_PENDING.md
@@ -3,3 +3,5 @@
 ### SDK Enhancements
 
 ### SDK Bugs
+* `aws/request`: Update Request Send to always ensure Request.HTTPResponse is populated.
+    * Fixes [#4211](https://github.com/aws/aws-sdk-go/issues/4211)
diff --git a/aws/request/request.go b/aws/request/request.go
index fb0a68fce3..636d9ec943 100644
--- a/aws/request/request.go
+++ b/aws/request/request.go
@@ -4,6 +4,7 @@ import (
 	"bytes"
 	"fmt"
 	"io"
+	"io/ioutil"
 	"net/http"
 	"net/url"
 	"reflect"
@@ -525,6 +526,14 @@ func (r *Request) GetBody() io.ReadSeeker {
 // Send will not close the request.Request's body.
 func (r *Request) Send() error {
 	defer func() {
+		// Ensure a non-nil HTTPResponse parameter is set to ensure handlers
+		// checking for HTTPResponse values, don't fail.
+		if r.HTTPResponse == nil {
+			r.HTTPResponse = &http.Response{
+				Header: http.Header{},
+				Body:   ioutil.NopCloser(&bytes.Buffer{}),
+			}
+		}
 		// Regardless of success or failure of the request trigger the Complete
 		// request handlers.
 		r.Handlers.Complete.Run(r)
diff --git a/aws/request/request_test.go b/aws/request/request_test.go
index 024d1ba167..1d271f480d 100644
--- a/aws/request/request_test.go
+++ b/aws/request/request_test.go
@@ -1257,6 +1257,37 @@ func TestRequestMarshaledEndpointWithNonDefaultPort(t *testing.T) {
 	}
 }
 
+func TestRequestCompleteWithoutHTTPResponse(t *testing.T) {
+	s := awstesting.NewClient(aws.NewConfig().WithRegion("mock-region"))
+	r := s.NewRequest(&request.Operation{
+		Name:       "FooBar",
+		HTTPMethod: "GET",
+		HTTPPath:   "/",
+	}, nil, nil)
+	r.Handlers.Sign.Clear()
+	r.Handlers.Sign.PushFront(func(r *request.Request) {
+		r.Error = fmt.Errorf("failed")
+	})
+	r.Handlers.Complete.PushBack(func(r *request.Request) {
+		if r.HTTPResponse == nil {
+			t.Fatalf("expect HTTPResponse not to be nil")
+		}
+		if r.HTTPResponse.Header == nil {
+			t.Fatalf("expect HTTPResponse.Header not to be nil")
+		}
+		if r.HTTPResponse.Body == nil {
+			t.Fatalf("expect HTTPResponse.Body not to be nil")
+		}
+	})
+	err := r.Send()
+	if err == nil {
+		t.Fatalf("expect error, got none")
+	}
+	if e, a := "failed", err.Error(); !strings.Contains(a, e) {
+		t.Errorf("expect %v error in %v", e, a)
+	}
+}
+
 type stubSeekFail struct {
 	Err error
 }