dag: configure 502 if include references another (#5016)

Set 502 response if include references another root

Fixes #5016

Signed-off-by: Lan Liang <gcslyp@gmail.com>

internal/dag/httpproxy_processor.go

@@ -590,6 +590,18 @@ func addRoutes(vhost vhost, routes []*Route) {
 	}
 }
 
+func addStatusBadGatewayRoute(routes []*Route, conds []contour_api_v1.MatchCondition) []*Route {
+	if len(conds) > 0 {
+		routes = append(routes, &Route{
+			PathMatchCondition:        mergePathMatchConditions(conds),
+			HeaderMatchConditions:     mergeHeaderMatchConditions(conds),
+			QueryParamMatchConditions: mergeQueryParamMatchConditions(conds),
+			DirectResponse:            directResponse(http.StatusBadGateway, ""),
+		})
+	}
+	return routes
+}
+
 func (p *HTTPProxyProcessor) computeRoutes(
 	validCond *contour_api_v1.DetailedCondition,
 	rootProxy *contour_api_v1.HTTPProxy,
@@ -655,21 +667,15 @@ func (p *HTTPProxyProcessor) computeRoutes(
 				"include %s/%s not found", namespace, include.Name)
 
 			// Set 502 response when include was not found but include condition was valid.
-			if len(include.Conditions) > 0 {
-				routes = append(routes, &Route{
-					PathMatchCondition:        mergePathMatchConditions(include.Conditions),
-					HeaderMatchConditions:     mergeHeaderMatchConditions(include.Conditions),
-					QueryParamMatchConditions: mergeQueryParamMatchConditions(include.Conditions),
-					DirectResponse:            directResponse(http.StatusBadGateway, ""),
-				})
-			}
-
+			routes = addStatusBadGatewayRoute(routes, include.Conditions)
 			continue
 		}
 
 		if includedProxy.Spec.VirtualHost != nil {
 			validCond.AddErrorf(contour_api_v1.ConditionTypeIncludeError, "RootIncludesRoot",
 				"root httpproxy cannot include another root httpproxy")
+			// Set 502 response if include references another root
+			routes = addStatusBadGatewayRoute(routes, include.Conditions)
 			continue
 		}