Itojun, if you're serious about making this cross platform and
not require PF then code like this:

+#if NPF > 0
+               tagvalue = pf_tagname2tag(tag->sadb_x_tag_name);
+               /* tag refcnt++ */
+               newsp = key_getspbytag(tagvalue, xpl0->sadb_x_policy_dir);
+#else
+               panic("PF");
+#endif

has to change before it goes in NetBSD.

Darren