sys/netinet/ip_output.c

1601 	struct mbuf *copym;
1607 	copym = m_dup(m, M_NOWAIT);
1608 	if (copym != NULL && (!M_WRITABLE(copym) || copym->m_len < hlen))
1609 		copym = m_pullup(copym, hlen);
1610 	if (copym != NULL) {
1612 		if (copym->m_pkthdr.csum_flags & CSUM_DELAY_DATA) {
1613 			in_delayed_cksum(copym);
1614 			copym->m_pkthdr.csum_flags &= ~CSUM_DELAY_DATA;
1615 			copym->m_pkthdr.csum_flags |=
1617 			copym->m_pkthdr.csum_data = 0xffff;
1623 		ip = mtod(copym, struct ip *);
1625 		ip->ip_sum = in_cksum(copym, hlen);
1626 		if_simloop(ifp, copym, AF_INET, 0);