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Provide fallback if config cannot be loaded

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This commit is contained in:
Daniil Gentili 2019-06-12 12:58:45 +02:00
parent ab07b327f0
commit 3e4a66c1bf
1 changed files with 63 additions and 22 deletions
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85
lib/Rfc1035StubResolver.php
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@ -19,6 +19,9 @@ use function Amp\call;
final class Rfc1035StubResolver implements Resolver
{
const CACHE_PREFIX = "amphp.dns.";
const CONFIG_NOT_LOADED = 0;
const CONFIG_LOADED = 1;
const CONFIG_FAILED = 2;
/** @var \Amp\Dns\ConfigLoader */
private $configLoader;
@ -29,6 +32,9 @@ final class Rfc1035StubResolver implements Resolver
/** @var \Amp\Dns\Config|null */
private $config;
/** @var int */
private $configStatus = self::CONFIG_NOT_LOADED;
/** @var Promise|null */
private $pendingConfig;
@ -49,10 +55,10 @@ final class Rfc1035StubResolver implements Resolver
public function __construct(Cache $cache = null, ConfigLoader $configLoader = null)
{
$this->cache = $cache ?? new ArrayCache(5000 /* default gc interval */, 256 /* size */);
$this->cache = $cache ?? new ArrayCache(5000/* default gc interval */, 256/* size */);
$this->configLoader = $configLoader ?? (\stripos(PHP_OS, "win") === 0
? new WindowsConfigLoader
: new UnixConfigLoader);
? new WindowsConfigLoader
: new UnixConfigLoader);
$this->questionFactory = new QuestionFactory;
@ -88,8 +94,25 @@ final class Rfc1035StubResolver implements Resolver
}
return call(function () use ($name, $typeRestriction) {
if (!$this->config) {
yield $this->reloadConfig();
if (!$this->configStatus) {
try {
yield $this->reloadConfig();
} catch (ConfigException $e) {
$this->configStatus = self::CONFIG_FAILED;
}
}
if ($this->configStatus === self::CONFIG_FAILED) {
if (!\in_array($typeRestriction, [Record::A, null])) {
return [];
}
$result = \gethostbynamel($name);
if ($result === false) {
return [];
}
foreach ($result as &$record) {
$record = new Record($record, Record::A, null);
}
return $result;
}
switch ($typeRestriction) {
@ -126,8 +149,8 @@ final class Rfc1035StubResolver implements Resolver
// Usually, these queries are already resolved via queryHosts()
if ($name === 'localhost') {
return $typeRestriction === Record::AAAA
? [new Record('::1', Record::AAAA, null)]
: [new Record('127.0.0.1', Record::A, null)];
? [new Record('::1', Record::AAAA, null)]
: [new Record('127.0.0.1', Record::A, null)];
}
for ($redirects = 0; $redirects < 5; $redirects++) {
@ -155,7 +178,7 @@ final class Rfc1035StubResolver implements Resolver
$errors[] = $reason->getMessage();
}
throw new DnsException("All query attempts failed for {$name}: " . \implode(", ", $errors), 0, $e);
throw new DnsException("All query attempts failed for {$name}: ".\implode(", ", $errors), 0, $e);
}
}
} catch (NoRecordException $e) {
@ -192,6 +215,7 @@ final class Rfc1035StubResolver implements Resolver
$promise = call(function () {
$this->config = yield $this->configLoader->loadConfig();
$this->configStatus = self::CONFIG_LOADED;
});
$this->pendingConfig = $promise;
@ -225,15 +249,32 @@ final class Rfc1035StubResolver implements Resolver
/** @inheritdoc */
public function query(string $name, int $type): Promise
{
$pendingQueryKey = $type . " " . $name;
$pendingQueryKey = $type." ".$name;
if (isset($this->pendingQueries[$pendingQueryKey])) {
return $this->pendingQueries[$pendingQueryKey];
}
$promise = call(function () use ($name, $type) {
if (!$this->config) {
yield $this->reloadConfig();
if (!$this->configStatus) {
try {
yield $this->reloadConfig();
} catch (ConfigException $e) {
$this->configStatus = self::CONFIG_FAILED;
}
}
if ($this->configStatus === self::CONFIG_FAILED) {
if ($type !== Record::A) {
return [];
}
$result = \gethostbynamel($name);
if ($result === false) {
return [];
}
foreach ($result as &$record) {
$record = new Record($record, Record::A, null);
}
return $result;
}
$name = $this->normalizeName($name, $type);
@ -249,7 +290,7 @@ final class Rfc1035StubResolver implements Resolver
$attempt = 0;
/** @var Socket $socket */
$uri = $protocol . "://" . $nameservers[0];
$uri = $protocol."://".$nameservers[0];
$socket = yield $this->getSocket($uri);
$attemptDescription = [];
@ -262,7 +303,7 @@ final class Rfc1035StubResolver implements Resolver
/** @var Socket $server */
$i = $attempt % \count($nameservers);
$uri = $protocol . "://" . $nameservers[$i];
$uri = $protocol."://".$nameservers[$i];
$socket = yield $this->getSocket($uri);
}
@ -285,12 +326,12 @@ final class Rfc1035StubResolver implements Resolver
// Retry with TCP, don't count attempt
$protocol = "tcp";
$i = $attempt % \count($nameservers);
$uri = $protocol . "://" . $nameservers[$i];
$uri = $protocol."://".$nameservers[$i];
$socket = yield $this->getSocket($uri);
continue;
}
throw new DnsException("Server returned a truncated response for '{$name}' (" . Record::getName($type) . ")");
throw new DnsException("Server returned a truncated response for '{$name}' (".Record::getName($type).")");
}
$answers = $response->getAnswerRecords();
@ -314,7 +355,7 @@ final class Rfc1035StubResolver implements Resolver
if (!isset($result[$type])) {
// "it MUST NOT cache it for longer than five (5) minutes" per RFC 2308 section 7.1
$this->cache->set($this->getCacheKey($name, $type), \json_encode([]), 300);
throw new NoRecordException("No records returned for '{$name}' (" . Record::getName($type) . ")");
throw new NoRecordException("No records returned for '{$name}' (".Record::getName($type).")");
}
return \array_map(function ($data) use ($type, $ttls) {
@ -328,7 +369,7 @@ final class Rfc1035StubResolver implements Resolver
});
$i = ++$attempt % \count($nameservers);
$uri = $protocol . "://" . $nameservers[$i];
$uri = $protocol."://".$nameservers[$i];
$socket = yield $this->getSocket($uri);
continue;
@ -344,9 +385,9 @@ final class Rfc1035StubResolver implements Resolver
));
});
$this->pendingQueries[$type . " " . $name] = $promise;
$this->pendingQueries[$type." ".$name] = $promise;
$promise->onResolve(function () use ($name, $type) {
unset($this->pendingQueries[$type . " " . $name]);
unset($this->pendingQueries[$type." ".$name]);
});
return $promise;
@ -357,9 +398,9 @@ final class Rfc1035StubResolver implements Resolver
if ($type === Record::PTR) {
if (($packedIp = @\inet_pton($name)) !== false) {
if (isset($packedIp[4])) { // IPv6
$name = \wordwrap(\strrev(\bin2hex($packedIp)), 1, ".", true) . ".ip6.arpa";
$name = \wordwrap(\strrev(\bin2hex($packedIp)), 1, ".", true).".ip6.arpa";
} else { // IPv4
$name = \inet_ntop(\strrev($packedIp)) . ".in-addr.arpa";
$name = \inet_ntop(\strrev($packedIp)).".in-addr.arpa";
}
}
} elseif (\in_array($type, [Record::A, Record::AAAA])) {
@ -390,7 +431,7 @@ final class Rfc1035StubResolver implements Resolver
private function getCacheKey(string $name, int $type): string
{
return self::CACHE_PREFIX . $name . "#" . $type;
return self::CACHE_PREFIX.$name."#".$type;
}
private function decodeCachedResult(string $name, int $type, string $encoded)