You're correct physi! There is actually a function named NetEnumerateTrustedDomains from Win32::LanMan that should do the trick. From documentation:

NetEnumerateTrustedDomains($server, \@domains)
Enumerates all trusted domain names. The command will be executed on s
+erver $server.
[download]

Update: I guess rchiav found this function abut the same time as I did :)