Allow CORS Access-Control-Allow-Origin: null (kubernetes#12402)

Author: elizabeth-dev

internal/ingress/annotations/cors/main.go

@@ -40,12 +40,12 @@ var (
 	// that could cause the Response to contain some internal value/variable (like returning $pid, $upstream_addr, etc)
 	// Origin must contain a http/s Origin (including or not the port) or the value '*'
 	// This Regex is composed of the following:
-	// * Sets a group that can be (https?://)?*?.something.com:port?
+	// * Sets a group that can be (https?://)?*?.something.com:port? OR null
 	// * Allows this to be repeated as much as possible, and separated by comma
 	// Otherwise it should be '*'
-	corsOriginRegexValidator = regexp.MustCompile(`^(((([a-z]+://)?(\*\.)?[A-Za-z0-9\-.]*(:\d+)?,?)+)|\*)?$`)
+	corsOriginRegexValidator = regexp.MustCompile(`^((((([a-z]+://)?(\*\.)?[A-Za-z0-9\-.]*(:\d+)?,?)|null)+)|\*)?$`)
 	// corsOriginRegex defines the regex for validation inside Parse
-	corsOriginRegex = regexp.MustCompile(`^([a-z]+://(\*\.)?[A-Za-z0-9\-.]*(:\d+)?|\*)?$`)
+	corsOriginRegex = regexp.MustCompile(`^([a-z]+://(\*\.)?[A-Za-z0-9\-.]*(:\d+)?|\*|null)?$`)
 	// Method must contain valid methods list (PUT, GET, POST, BLA)
 	// May contain or not spaces between each verb
 	corsMethodsRegex = regexp.MustCompile(`^([A-Za-z]+,?\s?)+$`)
@@ -78,7 +78,7 @@ var corsAnnotation = parser.Annotation{
 			Scope:     parser.AnnotationScopeIngress,
 			Risk:      parser.AnnotationRiskMedium,
 			Documentation: `This annotation controls what's the accepted Origin for CORS.
-			This is a multi-valued field, separated by ','. It must follow this format: protocol://origin-site.com or protocol://origin-site.com:port
+			This is a multi-valued field, separated by ','. It must follow this format: protocol://origin-site.com, protocol://origin-site.com:port, null, or *.
 			It also supports single level wildcard subdomains and follows this format: https://*.foo.bar, http://*.bar.foo:8080 or myprotocol://*.abc.bar.foo:9000
 			Protocol can be any lowercase string, like http, https, or mycustomprotocol.`,
 		},

internal/ingress/annotations/cors/main_test.go

@@ -82,7 +82,7 @@ func TestIngressCorsConfigValid(t *testing.T) {
 	data[parser.GetAnnotationWithPrefix(corsAllowHeadersAnnotation)] = "DNT,X-CustomHeader, Keep-Alive,User-Agent"
 	data[parser.GetAnnotationWithPrefix(corsAllowCredentialsAnnotation)] = "false"
 	data[parser.GetAnnotationWithPrefix(corsAllowMethodsAnnotation)] = "GET, PATCH"
-	data[parser.GetAnnotationWithPrefix(corsAllowOriginAnnotation)] = "https://origin123.test.com:4443"
+	data[parser.GetAnnotationWithPrefix(corsAllowOriginAnnotation)] = "null, https://origin123.test.com:4443"
 	data[parser.GetAnnotationWithPrefix(corsExposeHeadersAnnotation)] = "*, X-CustomResponseHeader"
 	data[parser.GetAnnotationWithPrefix(corsMaxAgeAnnotation)] = "600"
 	ing.SetAnnotations(data)
@@ -113,7 +113,7 @@ func TestIngressCorsConfigValid(t *testing.T) {
 		t.Errorf("expected %v but returned %v", data[parser.GetAnnotationWithPrefix(corsAllowMethodsAnnotation)], nginxCors.CorsAllowMethods)
 	}
 
-	if nginxCors.CorsAllowOrigin[0] != "https://origin123.test.com:4443" {
+	if !reflect.DeepEqual(nginxCors.CorsAllowOrigin, []string{"null", "https://origin123.test.com:4443"}) {
 		t.Errorf("expected %v but returned %v", data[parser.GetAnnotationWithPrefix(corsAllowOriginAnnotation)], nginxCors.CorsAllowOrigin)
 	}
 
@@ -176,7 +176,7 @@ func TestIngressCorsConfigInvalid(t *testing.T) {
 	}
 }
 
-func TestIngresCorsConfigAllowOriginWithTrailingComma(t *testing.T) {
+func TestIngressCorsConfigAllowOriginWithTrailingComma(t *testing.T) {
 	ing := buildIngress()
 
 	data := map[string]string{}
@@ -206,6 +206,36 @@ func TestIngresCorsConfigAllowOriginWithTrailingComma(t *testing.T) {
 	}
 }
 
+func TestIngressCorsConfigAllowOriginNull(t *testing.T) {
+	ing := buildIngress()
+
+	data := map[string]string{}
+	data[parser.GetAnnotationWithPrefix(corsEnableAnnotation)] = enableAnnotation
+
+	// Include a trailing comma and an empty value between the commas.
+	data[parser.GetAnnotationWithPrefix(corsAllowOriginAnnotation)] = "https://origin123.test.com:4443,null,https://origin321.test.com:4443"
+	ing.SetAnnotations(data)
+
+	corst, err := NewParser(&resolver.Mock{}).Parse(ing)
+	if err != nil {
+		t.Errorf("error parsing annotations: %v", err)
+	}
+
+	nginxCors, ok := corst.(*Config)
+	if !ok {
+		t.Errorf("expected a Config type but returned %t", corst)
+	}
+
+	if !nginxCors.CorsEnabled {
+		t.Errorf("expected %v but returned %v", data[parser.GetAnnotationWithPrefix(corsEnableAnnotation)], nginxCors.CorsEnabled)
+	}
+
+	expectedCorsAllowOrigins := []string{"https://origin123.test.com:4443", "null", "https://origin321.test.com:4443"}
+	if !reflect.DeepEqual(nginxCors.CorsAllowOrigin, expectedCorsAllowOrigins) {
+		t.Errorf("expected %v but returned %v", expectedCorsAllowOrigins, nginxCors.CorsAllowOrigin)
+	}
+}
+
 func TestIngressCorsConfigAllowOriginWithNonHttpProtocol(t *testing.T) {
 	ing := buildIngress()