hook_alloc
ins->ipdn_v4in = hook_alloc(HOOK_VERSION);
ins->ipdn_v4out = hook_alloc(HOOK_VERSION);
ins->ipdn_v6in = hook_alloc(HOOK_VERSION);
ins->ipdn_v6out = hook_alloc(HOOK_VERSION);
extern hook_t *hook_alloc(const int version);
(x) = hook_alloc(HOOK_VERSION); \