From e2224a69f98c8fdc9c4a9328cbf749b9bd9358a7 Mon Sep 17 00:00:00 2001
From: Sean McGrail <mcgrails@amazon.com>
Date: Mon, 26 Apr 2021 14:31:10 -0700
Subject: [PATCH] private/protocol/xml/xmlutil: Updated XML encoding to ensure
 line feed is escaped.

---
 private/protocol/xml/xmlutil/build_test.go    |  6 +++
 private/protocol/xml/xmlutil/xml_to_struct.go | 47 ++++++++++++-------
 2 files changed, 36 insertions(+), 17 deletions(-)

diff --git a/private/protocol/xml/xmlutil/build_test.go b/private/protocol/xml/xmlutil/build_test.go
index 0ab5b6866e5..a50900c857a 100644
--- a/private/protocol/xml/xmlutil/build_test.go
+++ b/private/protocol/xml/xmlutil/build_test.go
@@ -153,6 +153,12 @@ func TestBuildXML(t *testing.T) {
 			Input:  &namedEmptyPayload{},
 			Expect: "<namedEmptyPayload></namedEmptyPayload>",
 		},
+		"escape line feed and carriage return": {
+			Input: &implicitPayload{
+				StrVal: aws.String("this\nstring\rhas\r\nescapable\n\rcharacters"),
+			},
+			Expect: "<StrVal>this&#xA;string&#xD;has&#xD;&#xA;escapable&#xA;&#xD;characters</StrVal>",
+		},
 	}
 
 	for name, c := range cases {
diff --git a/private/protocol/xml/xmlutil/xml_to_struct.go b/private/protocol/xml/xmlutil/xml_to_struct.go
index 42f71648eee..2cf112a7e88 100644
--- a/private/protocol/xml/xmlutil/xml_to_struct.go
+++ b/private/protocol/xml/xmlutil/xml_to_struct.go
@@ -18,6 +18,14 @@ type XMLNode struct {
 	parent     *XMLNode
 }
 
+// textEncoder is a string type alias that implemnts the TextMarshaler interface.
+// This alias type is used to ensure that the line feed (\n) (U+000A) is escaped.
+type textEncoder string
+
+func (t textEncoder) MarshalText() (text []byte, err error) {
+	return []byte(t), nil
+}
+
 // NewXMLElement returns a pointer to a new XMLNode initialized to default values.
 func NewXMLElement(name xml.Name) *XMLNode {
 	return &XMLNode{
@@ -130,30 +138,35 @@ func StructToXML(e *xml.Encoder, node *XMLNode, sorted bool) error {
 		attrs = sortedAttrs
 	}
 
-	e.EncodeToken(xml.StartElement{Name: node.Name, Attr: attrs})
+	startElement := xml.StartElement{Name: node.Name, Attr: attrs}
 
 	if node.Text != "" {
-		e.EncodeToken(xml.CharData([]byte(node.Text)))
-	} else if sorted {
-		sortedNames := []string{}
-		for k := range node.Children {
-			sortedNames = append(sortedNames, k)
-		}
-		sort.Strings(sortedNames)
+		e.EncodeElement(textEncoder(node.Text), startElement)
+	} else {
+		e.EncodeToken(startElement)
 
-		for _, k := range sortedNames {
-			for _, v := range node.Children[k] {
-				StructToXML(e, v, sorted)
+		if sorted {
+			sortedNames := []string{}
+			for k := range node.Children {
+				sortedNames = append(sortedNames, k)
 			}
-		}
-	} else {
-		for _, c := range node.Children {
-			for _, v := range c {
-				StructToXML(e, v, sorted)
+			sort.Strings(sortedNames)
+
+			for _, k := range sortedNames {
+				for _, v := range node.Children[k] {
+					StructToXML(e, v, sorted)
+				}
+			}
+		} else {
+			for _, c := range node.Children {
+				for _, v := range c {
+					StructToXML(e, v, sorted)
+				}
 			}
 		}
+
+		e.EncodeToken(xml.EndElement{Name: node.Name})
 	}
 
-	e.EncodeToken(xml.EndElement{Name: node.Name})
 	return e.Flush()
 }