NAME

       ipsec_goodmask,  ipsec_masktobits,  ipsec_bitstomask  -  check  if Internet subnet mask is
       valid, convert Internet subnet mask to bit count, convert bit  count  to  Internet  subnet
       mask

SYNOPSIS

       #include <freeswan.h>

       int goodmask(struct in_addr mask);
       int masktobits(struct in_addr mask);
       struct in_addr bitstomask(int n);

DESCRIPTION

       These functions are obsolete; see ipsec_masktocount(3) for a partial replacement.

       Goodmask  reports  whether  the  subnet  mask is a valid one, i.e. consists of a (possibly
       empty) sequence of 1s followed by a (possibly empty) sequence of 0s.  Masktobits  takes  a
       (valid)  subnet  mask  and  returns the number of 1 bits in it.  Bitstomask reverses this,
       returning the subnet mask corresponding to bit count n.

       All masks are in network byte order.

SEE ALSO

       inet(3), ipsec_atosubnet(3)

DIAGNOSTICS

       Masktobits returns -1 for an invalid mask.  Bitstomask returns an  all-zeros  mask  for  a
       negative or out-of-range n.

HISTORY

       Written for the FreeS/WAN project by Henry Spencer.

BUGS

       The  error-reporting  convention  of  bitstomask  is  less than ideal; zero is sometimes a
       legitimate mask.

                                           11 June 2001                         IPSEC_GOODMASK(3)