/*
* Get at least "siz" bytes of correctly aligned data.
* When called the mbuf pointers are not necessarily correct,
* dsosp points to what ought to be in m_data and left contains
* what ought to be in m_len.
* This is used by the macros nfsm_dissect and nfsm_dissecton for tough
* cases. (The macros use the vars. dpos and dpos2)
*/