finally, a complete mbuf. enjoy!


 struct mbuf {
     struct  m_hdr m_hdr;
     union {
         struct {
             struct  pkthdr MH_pkthdr; /* M_PKTHDR set */
             union {
                 struct  mbuf_ext MH_ext; /* M_EXT set */
                 char    MH_databuf[MHLEN];
             } MH_dat;
         } MH;
         char    M_databuf[MLEN]; /* !M_PKTHDR, !M_EXT */
     } M_dat;
 };
 #define m_next      m_hdr.mh_next
 #define m_len       m_hdr.mh_len
 #define m_data      m_hdr.mh_data
 #define m_type      m_hdr.mh_type
 #define m_flags     m_hdr.mh_flags
 #define m_nextpkt   m_hdr.mh_nextpkt
 #define m_act       m_nextpkt
 #define m_pkthdr    M_dat.MH.MH_pkthdr
 #define m_ext       M_dat.MH.MH_dat.MH_ext
 #define m_pktdat    M_dat.MH.MH_dat.MH_databuf
 #define m_dat       M_dat.M_databuf