Net::hostent

Section: Perl Programmers Reference Guide (3perl)
Updated: 2019-04-20
Page Index

NAME

Net::hostent - by-name interface to Perl's built-in gethost*() functions

SYNOPSIS

 use Net::hostent;

DESCRIPTION

This module's default exports override the core gethostbyname() and gethostbyaddr() functions, replacing them with versions that return ``Net::hostent'' objects. This object has methods that return the similarly named structure field name from the C's hostent structure from netdb.h; namely name, aliases, addrtype, length, and addr_list. The aliases and addr_list methods return array reference, the rest scalars. The addr method is equivalent to the zeroth element in the addr_list array reference.

You may also import all the structure fields directly into your namespace as regular variables using the :FIELDS import tag. (Note that this still overrides your core functions.) Access these fields as variables named with a preceding "h_". Thus, "$host_obj->name()" corresponds to $h_name if you import the fields. Array references are available as regular array variables, so for example "@{ $host_obj->aliases() }" would be simply @h_aliases.

The gethost() function is a simple front-end that forwards a numeric argument to gethostbyaddr() by way of Socket::inet_aton, and the rest to gethostbyname().

To access this functionality without the core overrides, pass the "use" an empty import list, and then access function functions with their full qualified names. On the other hand, the built-ins are still available via the "CORE::" pseudo-package.

EXAMPLES

 use Net::hostent;
 use Socket;

 @ARGV = ('netscape.com') unless @ARGV;

 for $host ( @ARGV ) {

    unless ($h = gethost($host)) {
        warn "$0: no such host: $host\n";
        next;
    }

    printf "\n%s is %s%s\n", 
            $host, 
            lc($h->name) eq lc($host) ? "" : "*really* ",
            $h->name;

    print "\taliases are ", join(", ", @{$h->aliases}), "\n"
                if @{$h->aliases};     

    if ( @{$h->addr_list} > 1 ) { 
        my $i;
        for $addr ( @{$h->addr_list} ) {
            printf "\taddr #%d is [%s]\n", $i++, inet_ntoa($addr);
        } 
    } else {
        printf "\taddress is [%s]\n", inet_ntoa($h->addr);
    } 

    if ($h = gethostbyaddr($h->addr)) {
        if (lc($h->name) ne lc($host)) {
            printf "\tThat addr reverses to host %s!\n", $h->name;
            $host = $h->name;
            redo;
        } 
    }
 }

NOTE

While this class is currently implemented using the Class::Struct module to build a struct-like class, you shouldn't rely upon this.

AUTHOR

Tom Christiansen