debugnet_msg_hdr
struct debugnet_msg_hdr *dn_msg_hdr;
sizeof(struct udpiphdr) - sizeof(struct debugnet_msg_hdr));
m->m_len = sizeof(struct debugnet_msg_hdr);
m->m_pkthdr.len = sizeof(struct debugnet_msg_hdr);
MH_ALIGN(m, sizeof(struct debugnet_msg_hdr));
dn_msg_hdr = mtod(m, struct debugnet_msg_hdr *);
const struct debugnet_msg_hdr *dnh;
dnh = mtod(m, const struct debugnet_msg_hdr *);
#define netdump_msg_hdr debugnet_msg_hdr