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#! /usr/bin/perl
# vim:ts=8:sw=8
use strict;
use warnings;
use utf8;
use DBI;
use Data::Dumper;
use JSON;
use nms;
use Digest::SHA;
use FreezeThaw;
use URI::Escape;
package nms::web;
use base 'Exporter';
our %get_params;
our %json;
our @EXPORT = qw(finalize_output now json $dbh db_safe_quote %get_params get_input %json);
our $dbh;
our $now;
our $when;
our %cc;
sub get_input {
my $in = "";
while(<STDIN>) { $in .= $_; }
return $in;
}
# Print cache-control from %cc
sub printcc {
my $line = "";
my $first = "";
foreach my $tmp (keys(%cc)) {
$line .= $first . $tmp . "=" . $cc{$tmp};
$first = ", ";
}
print 'Cache-Control: ' . $line . "\n";
}
sub db_safe_quote {
my $word = $_[0];
my $term = $get_params{$word};
if (!defined($term)) {
if(defined($_[1])) {
$term = $_[1];
} else {
die "Missing CGI param $word";
}
}
return $dbh->quote($term) || die;
}
# returns a valid $when statement
# Also sets cache-control headers if time is overridden
# This can be called explicitly to override the window of time we evaluate.
# Normally up to 15 minutes old data will be returned, but for some API
# endpoints it is better to return no data than old data (e.g.: ping).
sub setwhen {
$now = "now()";
my $window = '8m';
my $offset = '0s';
if (@_ > 0) {
$window = $_[0];
}
if (@_ > 1) {
$offset = $_[1];
}
if (defined($get_params{'now'})) {
$now = db_safe_quote('now') . "::timestamp with time zone ";
$cc{'max-age'} = "3600";
}
$now = "(" . $now . " - '" . $offset . "'::interval)";
$when = " time > " . $now . " - '".$window."'::interval and time < " . $now . " ";
}
sub finalize_output {
my $query;
my $hash = Digest::SHA::sha512_base64(FreezeThaw::freeze(%json));
$dbh->commit;
$query = $dbh->prepare('select extract(epoch from date_trunc(\'seconds\', ' . $now . ')) as time;');
$query->execute();
$json{'time'} = int($query->fetchrow_hashref()->{'time'});
$json{'hash'} = $hash;
printcc;
print "Etag: $hash\n";
print "Access-Control-Allow-Origin: *\n";
print "Access-Control-Allow-Methods: HEAD, GET\n";
print "Content-Type: text/json; charset=utf-8\n\n";
print JSON::XS::encode_json(\%json);
print "\n";
}
sub populate_params {
my $querystring = $ENV{'QUERY_STRING'} || "";
foreach my $hdr (split("&",$querystring)) {
my ($key, $value) = split("=",$hdr,"2");
$get_params{$key} = URI::Escape::uri_unescape($value);
}
}
BEGIN {
$cc{'stale-while-revalidate'} = "3600";
$cc{'max-age'} = "20";
$dbh = nms::db_connect();
populate_params();
setwhen();
}
1;
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