Reference

ipsec_rangetosubnet(3)

convert address range to subnet

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 */

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