check Content-Encoding header value

ridgenative.go

@@ -341,7 +341,7 @@ func (rw *responseWriter) encodeBody() string {
 	}
 
 	if typ := rw.header.Get("Content-Type"); typ != "" {
-		rw.isBinary = isBinary(typ)
+		rw.isBinary = isBinary(rw.header)
 	} else {
 		rw.detectContentType()
 	}
@@ -356,11 +356,27 @@ func (rw *responseWriter) encodeBody() string {
 func (rw *responseWriter) detectContentType() {
 	contentType := http.DetectContentType(rw.w.Bytes())
 	rw.header.Set("Content-Type", contentType)
-	rw.isBinary = isBinary(contentType)
+	rw.isBinary = isBinary(rw.header)
 }
 
 // assume text/*, application/json, application/javascript, application/xml, */*+json, */*+xml as text
-func isBinary(contentType string) bool {
+func isBinary(headers http.Header) bool {
+	contentEncoding := headers.Values("Content-Encoding")
+	if len(contentEncoding) > 0 {
+		// typically, gzip, deflate, br, etc.
+		// these compressed encodings are not text, they are binary.
+		return true
+	}
+
+	// custom content encoding for Lambda
+	// it is compatible with AWS Lambda Rust Runtime.
+	// https://github.com/awslabs/aws-lambda-rust-runtime/blob/11d5669542d38ba2e1b5aa2d64b8e445d93718ea/lambda-http/src/response.rs#L303-L307
+	lambdaContentEncoding := headers.Get("X-Lambda-Http-Content-Encoding")
+	if lambdaContentEncoding == "text" {
+		return false
+	}
+
+	contentType := headers.Get("Content-Type")
 	i := strings.Index(contentType, ";")
 	if i == -1 {
 		i = len(contentType)
@@ -372,6 +388,7 @@ func isBinary(contentType string) bool {
 	}
 	mainType := mediaType[:i]
 
+	// common text mime types
 	if strings.EqualFold(mainType, "text") {
 		return false
 	}
@@ -388,6 +405,7 @@ func isBinary(contentType string) bool {
 		return false
 	}
 
+	// custom text mime types, such as application/*+json, application/*+xml
 	i = strings.LastIndex(mediaType, "+")
 	if i == -1 {
 		i = 0
@@ -402,6 +420,8 @@ func isBinary(contentType string) bool {
 	if strings.EqualFold(suffix, "+xml") {
 		return false
 	}
+
+	// assume it's binary
 	return true
 }
 

ridgenative_test.go

@@ -952,31 +952,136 @@ func TestLambdaHandlerStreaming(t *testing.T) {
 
 func TestIsBinary(t *testing.T) {
 	tests := []struct {
-		contentType string
-		want        bool
+		header http.Header
+		want   bool
 	}{
-		{"text/html", false},
-		{"text/plain", false},
-		{"text/xml", false},
-		{"application/json", false},
-		{"application/javascript", false},
-		{"application/yaml", false},
-		{"application/xml", false},
-		{"application/vnd.foo+json", false},
-		{"application/vnd.foo+yaml", false},
-		{"application/vnd.foo+xml", false},
-		{"application/vnd.foo+xml ; charset=utf8", false},
-		{"application/octet-stream", true},
-		{"image/jpeg", true},
-		{"audio/mpeg", true},
-		{"unknown-content-type", true},
-		{"", true},
+		// text/html but encoded as gzip
+		{
+			header: http.Header{
+				"Content-Type":     []string{"text/html; charset=utf-8"},
+				"Content-Encoding": []string{"gzip"},
+			},
+			want: true,
+		},
+
+		// custom content encoding for Lambda
+		{
+			header: http.Header{
+				"Content-Type":                   []string{"image/svg"},
+				"X-Lambda-Http-Content-Encoding": []string{"text"},
+			},
+			want: false,
+		},
+
+		// text/*
+		{
+			header: http.Header{
+				"Content-Type": []string{"text/html"},
+			},
+			want: false,
+		},
+		{
+			header: http.Header{
+				"Content-Type": []string{"text/plain"},
+			},
+			want: false,
+		},
+		{
+			header: http.Header{
+				"Content-Type": []string{"text/xml"},
+			},
+			want: false,
+		},
+
+		// data formats that are encoded as text
+		{
+			header: http.Header{
+				"Content-Type": []string{"application/json"},
+			},
+			want: false,
+		},
+		{
+			header: http.Header{
+				"Content-Type": []string{"application/javascript"},
+			},
+			want: false,
+		},
+		{
+			header: http.Header{
+				"Content-Type": []string{"application/yaml"},
+			},
+			want: false,
+		},
+		{
+			header: http.Header{
+				"Content-Type": []string{"application/xml"},
+			},
+			want: false,
+		},
+
+		// custom media types that are encoded as text
+		{
+			header: http.Header{
+				"Content-Type": []string{"application/foo+json"},
+			},
+			want: false,
+		},
+		{
+			header: http.Header{
+				"Content-Type": []string{"application/foo+yaml"},
+			},
+			want: false,
+		},
+		{
+			header: http.Header{
+				"Content-Type": []string{"application/foo+xml"},
+			},
+			want: false,
+		},
+		{
+			header: http.Header{
+				"Content-Type": []string{"application/foo+xml ; charset=utf8"},
+			},
+			want: false,
+		},
+
+		// common binary formats
+		{
+			header: http.Header{
+				"Content-Type": []string{"application/octet-stream"},
+			},
+			want: true,
+		},
+		{
+			header: http.Header{
+				"Content-Type": []string{"image/jpeg"},
+			},
+			want: true,
+		},
+		{
+			header: http.Header{
+				"Content-Type": []string{"audio/mpeg"},
+			},
+			want: true,
+		},
+		{
+			header: http.Header{
+				"Content-Type": []string{"unknown-content-type"},
+			},
+			want: true,
+		},
+		{
+			header: http.Header{
+				"Content-Type": []string{""},
+			},
+			want: true,
+		},
 	}
 
 	for _, tt := range tests {
-		got := isBinary(tt.contentType)
+		got := isBinary(tt.header)
 		if got != tt.want {
-			t.Errorf("isBinary(%q) = %v, want %v", tt.contentType, got, tt.want)
+			t.Errorf("isBinary(%v) = %v, want %v", tt.header, got, tt.want)
 		}
 	}
 }