debian man page for ipsec_bitstomask

IPSEC_GOODMASK(3)					     Library Functions Manual						 IPSEC_GOODMASK(3)

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)