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package DDG::Goodie::PublicDNS;
# ABSTRACT: Display a list of DNS servers which accept public queries.
use strict;
use DDG::Goodie;
use List::Util qw(max);
use YAML::XS 'LoadFile';
primary_example_queries 'public dns';
description 'list common public DNS servers and their IP addresses';
name 'Public DNS';
code_url 'https://github.com/duckduckgo/zeroclickinfo-goodies/blob/master/lib/DDG/Goodie/PublicDNS.pm';
category 'cheat_sheets';
topics 'sysadmin';
attribution github => ['warthurton', 'Wayne Arthurton'];
triggers end => "public dns", "dns server", "dns servers";
zci is_cached => 1;
zci answer_type => "public_dns";
my $providers = LoadFile(share('providers.yml'));
my @ordered_servers;
# Alphabetize the output while making the structure
# Easier to use below. The YAML is for human editing.
foreach my $provider (sort keys %$providers) {
my $info = $providers->{$provider};
$info->{provider} = $provider;
push @ordered_servers, $info;
}
undef $providers; # We're done with this now.
# Let the YAML stay the same, even if column ordering or titling changes.
my @display_cols = ({
key => 'provider',
title => 'Provider',
},
{
key => 'ip4',
title => 'IPv4',
},
{
key => 'ip6',
title => 'IPv6',
},
);
my $layout = {
extra_space => 1, # How many extra spaces in the text table?
text_corner => '+',
text_line => '-',
text_col => '|',
text_array => ', ',
html_array => '<br/>',
};
foreach my $column (@display_cols) {
$column->{width} = max(map { _max_str_len($_->{$column->{key}}) } @ordered_servers);
$column->{text_spacer} = sub {
my $to_show = shift;
# Everything is left-aligned
return
$layout->{text_col}
. (' ' x $layout->{extra_space})
. $to_show
. (' ' x max(0, $column->{width} - length($to_show) + $layout->{extra_space}));
};
}
my $table_spacer =
join($layout->{text_corner}, '', (map { $layout->{text_line} x ($_->{width} + $layout->{extra_space} * 2) } @display_cols), '') . "\n";
# Actually build the output.. finally!
my $text = $table_spacer;
my $html = '<table class="publicdns">';
# First the headers
$text .= join('', map { $_->{text_spacer}->($_->{title}) } @display_cols);
$html .= '<tr><th>' . join('</th><th>', map { $_->{title} } @display_cols) . '</th></tr>';
$text .= "|\n" . $table_spacer;
# And now the content
foreach my $server (@ordered_servers) {
$html .= "<tr>";
foreach my $column (@display_cols) {
if ($column->{key} ne 'provider') {
# Assuming we aren't displaying any non-provider string types!
$text .= $column->{text_spacer}->(join($layout->{text_array}, @{$server->{$column->{key}}}));
$html .= '<td>' . (join($layout->{html_array}, @{$server->{$column->{key}}})) . '</td>';
} else {
# Special-case provider
$text .= $column->{text_spacer}->($server->{$column->{key}});
$html .= '<td><a href="' . $server->{info_url} . '">' . $server->{$column->{key}} . '</a></td>';
}
}
$text .= $layout->{text_col} . "\n";
$html .= '</tr>';
}
$text .= $table_spacer;
$html .= '</table>';
my $heading = 'Public DNS Servers';
handle sub {
$text,
html => $html,
heading => $heading;
};
sub _max_str_len {
my $item = shift;
# We only have strings or arrays, so the max length of a string is the length of the string itself.
return (ref $item eq 'ARRAY') ? length(join($layout->{text_array}, @$item)) : length $item;
}
1;
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