class-ftp.php doesn't check correctly for IP validity under PHP5

[miqrogroove]

​http://core.trac.wordpress.org/browser/trunk/wp-admin/includes/class-ftp.php#L281

if(ip2long($ip) === -1) {

ip2long() never returns int(-1) in PHP5, except on 32-bit servers.

[nacin]

Checks for false in addition to -1.

[nacin]

Attached is a simple fix is to allow for both. Pretty sure that's exactly what the PHP docs suggest.

[miqrogroove]

Just for reference, Akismet is using

if ( $ip && long2ip(ip2long($ip)) ) {

Checking FALSE is much easier to read, so nacin's patch has my vote.

[nacin]

Yea, I was going to reference Akismet's use of long2ip & ip2long together. I'm pretty sure that's to correct to whether an IP is valid, not to check whether it is valid, if that makes sense, though I suppose both would work here.

Both examples appear in the PHP docs: ​http://php.net/ip2long.

[westi]

The check in akismet won't actually work anyway.

For Example "Howdy" && long2ip(ip2long("Howdy")) will evaluate to true as the string evaluates to true and the false returned by ip2long will cast to an int(0) fine which becomes an ip address of "0.0.0.0" which as a string with evaluate to true.

[westi]

(In [12387]) Fix the IP Address validation code in the FTP class. Fixes #11393 props nacin.