hdlc_header
struct hdlc_header *hdlc;
if (len < sizeof(struct hdlc_header)) {
m = m_pullup(m, sizeof(struct hdlc_header));
hdlc = mtod(m, struct hdlc_header *);
m->m_pkthdr.len -= sizeof(struct hdlc_header);
m->m_data += sizeof(struct hdlc_header);
m->m_len -= sizeof(struct hdlc_header);
m->m_pkthdr.len -= sizeof(struct hdlc_header);
m->m_data += sizeof(struct hdlc_header);
m->m_len -= sizeof(struct hdlc_header);
struct hdlc_header *hdlc;
M_PREPEND(m, sizeof(struct hdlc_header), M_DONTWAIT);
hdlc = mtod(m, struct hdlc_header *);
M_PREPEND(m, sizeof(struct hdlc_header), M_DONTWAIT);
hdlc = mtod(m, struct hdlc_header *);