httpcaddyfile: error on duplicate named_routes (#7800)

* fix: error on duplicate named_routes

Fixes issue #7798

Validate named route names before inserting them into the
named route map.

This prevents later definitions from overwriting existing
named routes and returns an error when a route name is
defined more than once.

* test: add test for duplicate named_routes

caddyconfig/httpcaddyfile/httptype.go

@@ -523,7 +523,11 @@ func (ServerType) extractNamedRoutes(
 			route.HandlersRaw = []json.RawMessage{caddyconfig.JSONModuleObject(handler, "handler", subroute.CaddyModule().ID.Name(), h.warnings)}
 		}
 
-		namedRoutes[sb.block.GetKeysText()[0]] = &route
+		key := sb.block.GetKeysText()[0]
+		if _, exists := namedRoutes[key]; exists {
+			return nil, fmt.Errorf("cannot have duplicate named_routes: %s", key)
+		}
+		namedRoutes[key] = &route
 	}
 	options["named_routes"] = namedRoutes
 

caddytest/integration/caddyfile_adapt/duplicate_named_route_challenge.caddyfiletest

@@ -0,0 +1,16 @@
+&(api) {
+	header X-Version v1
+	respond "API v1"
+}
+
+&(api) {
+	header X-Version v2
+	respond "API v2"
+}
+
+localhost {
+	invoke api
+}
+
+----------
+cannot have duplicate named_routes: api