parse_dest_constraint_hop
parse_dest_constraint_hop(os, &dc->to, hostkey_files);
parse_dest_constraint_hop(os, &dc->from, hostkey_files);
parse_dest_constraint_hop(cp, &dc->to, hostkey_files);
if ((r = parse_dest_constraint_hop(frombuf, &dc->from)) != 0 ||
(r = parse_dest_constraint_hop(tobuf, &dc->to)) != 0)