caddyhttp: Add {prefixed_query} placeholder

caddyconfig/httpcaddyfile/shorthands.go

@@ -60,6 +60,7 @@ func placeholderShorthands() []string {
 		"{method}", "{http.request.method}",
 		"{path}", "{http.request.uri.path}",
 		"{query}", "{http.request.uri.query}",
+		"{prefixed_query}", "{http.request.uri.prefixed_query}",
 		"{remote}", "{http.request.remote}",
 		"{remote_host}", "{http.request.remote.host}",
 		"{remote_port}", "{http.request.remote.port}",

modules/caddyhttp/replacer.go

@@ -186,6 +186,11 @@ func addHTTPVarsToReplacer(repl *caddy.Replacer, req *http.Request, w http.Respo
 				return path.Ext(req.URL.Path), true
 			case "http.request.uri.query":
 				return req.URL.RawQuery, true
+			case "http.request.uri.prefixed_query":
+				if req.URL.RawQuery == "" {
+					return "", true
+				}
+				return "?" + req.URL.RawQuery, true
 			case "http.request.duration":
 				start := GetVar(req.Context(), "start_time").(time.Time)
 				return time.Since(start), true