M_UDP_CSUM_IN_BAD
csum_flags |= M_UDP_CSUM_IN_BAD;
m->m_pkthdr.csum_flags |= M_UDP_CSUM_IN_BAD;
SET(m->m_pkthdr.csum_flags, M_UDP_CSUM_IN_BAD);
sumflags |= M_UDP_CSUM_IN_BAD;
if (m->m_pkthdr.csum_flags & M_UDP_CSUM_IN_BAD) {