pipex_common_input
m0 = pipex_common_input(session, m0, hlen, ntohs(pppoe.length), 0, ns);
m0 = pipex_common_input(session, m0, hlen, ntohs(gre->len), 1, ns);
m0 = pipex_common_input(session, m0, hlen, length, 1, nst);
struct mbuf *pipex_common_input(struct pipex_session *,