<?php
declare(strict_types=1);
/*
* This file is part of Badcow DNS Library.
*
* (c) Samuel Williams <sam@badcow.co>
*
* For the full copyright and license information, please view the LICENSE
* file that was distributed with this source code.
*/
namespace Badcow\DNS;
use Badcow\DNS\Parser\Tokens;
use Badcow\DNS\Rdata\A;
use Badcow\DNS\Rdata\AAAA;
use Badcow\DNS\Rdata\CNAME;
use Badcow\DNS\Rdata\DNAME;
use Badcow\DNS\Rdata\HINFO;
use Badcow\DNS\Rdata\LOC;
use Badcow\DNS\Rdata\MX;
use Badcow\DNS\Rdata\NS;
use Badcow\DNS\Rdata\NSEC3;
use Badcow\DNS\Rdata\NSEC3PARAM;
use Badcow\DNS\Rdata\PTR;
use Badcow\DNS\Rdata\RdataInterface;
use Badcow\DNS\Rdata\RRSIG;
use Badcow\DNS\Rdata\SOA;
use Badcow\DNS\Rdata\SRV;
use Badcow\DNS\Rdata\TXT;
class AlignedBuilder
{
/**
* The order in which Resource Records should appear in a zone.
*
* @var array
*/
private $order = [
SOA::TYPE,
NS::TYPE,
A::TYPE,
AAAA::TYPE,
CNAME::TYPE,
DNAME::TYPE,
MX::TYPE,
LOC::TYPE,
HINFO::TYPE,
TXT::TYPE,
PTR::TYPE,
SRV::TYPE,
NSEC3::TYPE,
NSEC3PARAM::TYPE,
RRSIG::TYPE,
];
/**
* @var callable[] array of Rdata type indexed, callables that handle the output formatting of Rdata
*/
private $rdataFormatters = [];
public function __construct()
{
$this->rdataFormatters = AlignedRdataFormatters::$rdataFormatters;
}
/**
* Adds or changes an Rdata output formatter.
*
* @param string $type the Rdata type to be handled by the $formatter
* @param callable $formatter callable that will handle the output formatting of the Rdata
*/
public function addRdataFormatter(string $type, callable $formatter): void
{
$this->rdataFormatters[$type] = $formatter;
}
public function getRdataFormatters(): array
{
return $this->rdataFormatters;
}
/**
* @return string[]
*/
public function getOrder(): array
{
return $this->order;
}
/**
* Set the order in which Resource Records should appear in a zone..
*
* @param string[] $order Simple string array of Rdata types
*/
public function setOrder(array $order): void
{
$this->order = $order;
}
/**
* Build an aligned BIND zone file.
*/
public function build(Zone $zone): string
{
$master = self::generateControlEntries($zone);
$resourceRecords = $zone->getResourceRecords();
$current = SOA::TYPE;
usort($resourceRecords, [__CLASS__, 'compareResourceRecords']);
list($namePadding, $ttlPadding, $typePadding, $classPadding, $rdataPadding) = self::getPadding($zone);
foreach ($resourceRecords as $resourceRecord) {
$rdata = $resourceRecord->getRdata();
if (null == $rdata) {
continue;
}
if ($rdata->getType() !== $current) {
$master .= Tokens::LINE_FEED.Tokens::SEMICOLON.Tokens::SPACE.$rdata->getType().' RECORDS'.Tokens::LINE_FEED;
$current = $rdata->getType();
}
$master .= sprintf(
'%s %s %s %s %s',
str_pad((string) $resourceRecord->getName(), $namePadding, Tokens::SPACE, STR_PAD_RIGHT),
str_pad((string) $resourceRecord->getTtl(), $ttlPadding, Tokens::SPACE, STR_PAD_RIGHT),
str_pad((string) $resourceRecord->getClass(), $classPadding, Tokens::SPACE, STR_PAD_RIGHT),
str_pad($rdata->getType(), $typePadding, Tokens::SPACE, STR_PAD_RIGHT),
$this->generateRdataOutput($rdata, $rdataPadding)
);
$master .= self::generateComment($resourceRecord);
$master .= Tokens::LINE_FEED;
}
return $master;
}
/**
* Returns the control entries as strings.
*/
private static function generateControlEntries(Zone $zone): string
{
$master = '$ORIGIN '.$zone->getName().Tokens::LINE_FEED;
if (null !== $zone->getDefaultTtl()) {
$master .= '$TTL '.$zone->getDefaultTtl().Tokens::LINE_FEED;
}
return $master;
}
/**
* Returns a comment string if the comments are not null, returns empty string otherwise.
*/
private static function generateComment(ResourceRecord $resourceRecord): string
{
if (null !== $resourceRecord->getComment()) {
return Tokens::SEMICOLON.Tokens::SPACE.$resourceRecord->getComment();
}
return '';
}
/**
* Compares two ResourceRecords to determine which is the higher order. Used with the usort() function.
*
* @param ResourceRecord $a The first ResourceRecord
* @param ResourceRecord $b The second ResourceRecord
*
* @return int $a is higher precedence than $b if return value is less than 0.
* $b is higher precedence than $a if return value is greater than 0.
* $a and $b have the same precedence if the return value is 0.
*/
public function compareResourceRecords(ResourceRecord $a, ResourceRecord $b): int
{
$a_rdata = (null === $a->getRdata()) ? '' : $a->getRdata()->toText();
$b_rdata = (null === $b->getRdata()) ? '' : $b->getRdata()->toText();
//If the types are the same, do a simple alphabetical comparison.
if ($a->getType() === $b->getType()) {
return strcmp($a->getName().$a_rdata, $b->getName().$b_rdata);
}
//Find the precedence (if any) for the two types.
$_a = array_search($a->getType(), $this->order);
$_b = array_search($b->getType(), $this->order);
//If neither types have defined precedence.
if (!is_int($_a) && !is_int($_b)) {
return strcmp($a->getType() ?? '', $b->getType() ?? '');
}
//If both types have defined precedence.
if (is_int($_a) && is_int($_b)) {
return $_a - $_b;
}
//If only $b has defined precedence.
if (false === $_a) {
return 1;
}
//If only $a has defined precedence.
return -1;
}
/**
* Composes the RDATA of the Resource Record.
*
* @param RdataInterface $rdata the Rdata to be formatted
* @param int $padding the number of spaces before the Rdata column
*/
private function generateRdataOutput(RdataInterface $rdata, int $padding): string
{
if (!array_key_exists($rdata->getType(), $this->rdataFormatters)) {
return $rdata->toText();
}
$formatted = call_user_func($this->rdataFormatters[$rdata->getType()], $rdata, $padding);
if (!is_string($formatted)) {
throw new \UnexpectedValueException(sprintf('Formatter for RType "%s" returned object type "%s", string expected.', $rdata->getType(), gettype($formatted)));
}
return $formatted;
}
/**
* Get the padding required for a zone.
*
* @param Zone $zone the DNS Zone being processed
*
* @return int[] Array order: [name, ttl, type, class, rdata]
*/
private static function getPadding(Zone $zone): array
{
$name = $ttl = $type = 0;
$class = 2;
/** @var ResourceRecord $resourceRecord */
foreach ($zone as $resourceRecord) {
$name = max($name, strlen($resourceRecord->getName() ?? ''));
$ttl = max($ttl, strlen((string) $resourceRecord->getTtl()));
$class = max($class, strlen($resourceRecord->getClass() ?? ''));
$type = max($type, strlen($resourceRecord->getType() ?? ''));
}
return [
$name,
$ttl,
$type,
$class,
$name + $ttl + $class + $type + 4,
];
}
}