NAME

       ipsec_rangetosubnet - convert address range to subnet

SYNOPSIS

       #include <freeswan.h>

       const char *rangetosubnet(const ip_address * start, const ip_address * stop,
                                 ip_subnet * dst);

DESCRIPTION

       Rangetosubnet accepts two IP addresses which define an address range, from start to stop
       inclusive, and converts this to a subnet if possible. The addresses must both be IPv4 or
       both be IPv6, and the address family of the resulting subnet is the same.

       Rangetosubnet returns NULL for success and a pointer to a string-literal error message for
       failure; see DIAGNOSTICS.

SEE ALSO

       ipsec_initsubnet(3), ipsec_ttosubnet(3)

DIAGNOSTICS

       Fatal errors in rangetosubnet are: mixed address families; unknown address family; start
       and stop do not define a subnet.

HISTORY

       Written for the FreeS/WAN project by Henry Spencer.

BUGS

       The restriction of error reports to literal strings (so that callers don´t need to worry
       about freeing them or copying them) does limit the precision of error reporting.

       The error-reporting convention lends itself to slightly obscure code, because many readers
       will not think of NULL as signifying success. A good way to make it clearer is to write
       something like:

           const char *error;

           error = rangetosubnet( /* ... */ );
           if (error != NULL) {
                   /* something went wrong */