In Perl, how can I check for the existence of Socket options without generating warnings?

Question

I'm checking for the existence and default values of various socket options using Perl.

#!/usr/bin/perl -w
use strict;
use Socket;

if (defined(SO_BROADCAST)) {
    print("SO_BROADCAST defined\n");
}

if (defined(SO_REUSEPORT)) {
    print("SO_REUSEPORT defined\n");
}

When I run this it outputs:

SO_BROADCAST defined

Your vendor has not defined Socket macro SO_REUSEPORT, used at ./checkopts.pl line 9

Is there a way to do this without generating warnings in the output?

Answer 1

That message is coming from AUTOLOAD in Socket.pm. When it finds a constant that isn't supported, it croaks. You can catch that with an eval:

 use Socket;

 if( defined eval { SO_REUSEPORT } ) {
      ...;
      }