unstable patch for 202312+

include/strings.h

@@ -0,0 +1,10 @@
+#pragma once
+
+#include "common.h"
+
+int ShouldRedirect(const char *host);
+
+// If host exactly matches a configured rewrite pair's <from>, writes <to> into out (up to outlen)
+// and returns 1; otherwise returns 0 and leaves out untouched.
+// Example: host "ns.rec.net", from "ns.rec.net", to "ns.recflare.net" -> "ns.recflare.net".
+int RewriteHost(const char *host, char *out, size_t outlen);