As sheepluva pointed out, allowing this message to be legal allows naughtiness. The server usage of this message does not seem to use this check.
/*
** $Id: ltm.h,v 2.6.1.1 2007/12/27 13:02:25 roberto Exp $
** Tag methods
** See Copyright Notice in lua.h
*/
#ifndef ltm_h
#define ltm_h
#include "lobject.h"
/*
* WARNING: if you change the order of this enumeration,
* grep "ORDER TM"
*/
typedef enum {
TM_INDEX,
TM_NEWINDEX,
TM_GC,
TM_MODE,
TM_EQ, /* last tag method with `fast' access */
TM_ADD,
TM_SUB,
TM_MUL,
TM_DIV,
TM_MOD,
TM_POW,
TM_UNM,
TM_LEN,
TM_LT,
TM_LE,
TM_CONCAT,
TM_CALL,
TM_N /* number of elements in the enum */
} TMS;
#define gfasttm(g,et,e) ((et) == NULL ? NULL : \
((et)->flags & (1u<<(e))) ? NULL : luaT_gettm(et, e, (g)->tmname[e]))
#define fasttm(l,et,e) gfasttm(G(l), et, e)
LUAI_DATA const char *const luaT_typenames[];
LUAI_FUNC const TValue *luaT_gettm (Table *events, TMS event, TString *ename);
LUAI_FUNC const TValue *luaT_gettmbyobj (lua_State *L, const TValue *o,
TMS event);
LUAI_FUNC void luaT_init (lua_State *L);
#endif