CasperSecurity
<?php
namespace React\Socket;
use React\Dns\Model\Message;
use React\Dns\Resolver\ResolverInterface;
use React\EventLoop\LoopInterface;
use React\EventLoop\TimerInterface;
use React\Promise;
use React\Promise\PromiseInterface;
/**
* @internal
*/
final class HappyEyeBallsConnectionBuilder
{
/**
* As long as we haven't connected yet keep popping an IP address of the connect queue until one of them
* succeeds or they all fail. We will wait 100ms between connection attempts as per RFC.
*
* @link https://tools.ietf.org/html/rfc8305#section-5
*/
const CONNECTION_ATTEMPT_DELAY = 0.1;
/**
* Delay `A` lookup by 50ms sending out connection to IPv4 addresses when IPv6 records haven't
* resolved yet as per RFC.
*
* @link https://tools.ietf.org/html/rfc8305#section-3
*/
const RESOLUTION_DELAY = 0.05;
public $loop;
public $connector;
public $resolver;
public $uri;
public $host;
public $resolved = array(
Message::TYPE_A => false,
Message::TYPE_AAAA => false,
);
public $resolverPromises = array();
public $connectionPromises = array();
public $connectQueue = array();
public $nextAttemptTimer;
public $parts;
public $ipsCount = 0;
public $failureCount = 0;
public $resolve;
public $reject;
public $lastErrorFamily;
public $lastError6;
public $lastError4;
public function __construct(LoopInterface $loop, ConnectorInterface $connector, ResolverInterface $resolver, $uri, $host, $parts)
{
$this->loop = $loop;
$this->connector = $connector;
$this->resolver = $resolver;
$this->uri = $uri;
$this->host = $host;
$this->parts = $parts;
}
public function connect()
{
$that = $this;
return new Promise\Promise(function ($resolve, $reject) use ($that) {
$lookupResolve = function ($type) use ($that, $resolve, $reject) {
return function (array $ips) use ($that, $type, $resolve, $reject) {
unset($that->resolverPromises[$type]);
$that->resolved[$type] = true;
$that->mixIpsIntoConnectQueue($ips);
// start next connection attempt if not already awaiting next
if ($that->nextAttemptTimer === null && $that->connectQueue) {
$that->check($resolve, $reject);
}
};
};
$that->resolverPromises[Message::TYPE_AAAA] = $that->resolve(Message::TYPE_AAAA, $reject)->then($lookupResolve(Message::TYPE_AAAA));
$that->resolverPromises[Message::TYPE_A] = $that->resolve(Message::TYPE_A, $reject)->then(function (array $ips) use ($that) {
// happy path: IPv6 has resolved already (or could not resolve), continue with IPv4 addresses
if ($that->resolved[Message::TYPE_AAAA] === true || !$ips) {
return $ips;
}
// Otherwise delay processing IPv4 lookup until short timer passes or IPv6 resolves in the meantime
$deferred = new Promise\Deferred(function () use (&$ips) {
// discard all IPv4 addresses if cancelled
$ips = array();
});
$timer = $that->loop->addTimer($that::RESOLUTION_DELAY, function () use ($deferred, $ips) {
$deferred->resolve($ips);
});
$that->resolverPromises[Message::TYPE_AAAA]->then(function () use ($that, $timer, $deferred, &$ips) {
$that->loop->cancelTimer($timer);
$deferred->resolve($ips);
});
return $deferred->promise();
})->then($lookupResolve(Message::TYPE_A));
}, function ($_, $reject) use ($that) {
$reject(new \RuntimeException(
'Connection to ' . $that->uri . ' cancelled' . (!$that->connectionPromises ? ' during DNS lookup' : '') . ' (ECONNABORTED)',
\defined('SOCKET_ECONNABORTED') ? \SOCKET_ECONNABORTED : 103
));
$_ = $reject = null;
$that->cleanUp();
});
}
/**
* @internal
* @param int $type DNS query type
* @param callable $reject
* @return \React\Promise\PromiseInterface<string[]> Returns a promise that
* always resolves with a list of IP addresses on success or an empty
* list on error.
*/
public function resolve($type, $reject)
{
$that = $this;
return $that->resolver->resolveAll($that->host, $type)->then(null, function (\Exception $e) use ($type, $reject, $that) {
unset($that->resolverPromises[$type]);
$that->resolved[$type] = true;
if ($type === Message::TYPE_A) {
$that->lastError4 = $e->getMessage();
$that->lastErrorFamily = 4;
} else {
$that->lastError6 = $e->getMessage();
$that->lastErrorFamily = 6;
}
// cancel next attempt timer when there are no more IPs to connect to anymore
if ($that->nextAttemptTimer !== null && !$that->connectQueue) {
$that->loop->cancelTimer($that->nextAttemptTimer);
$that->nextAttemptTimer = null;
}
if ($that->hasBeenResolved() && $that->ipsCount === 0) {
$reject(new \RuntimeException(
$that->error(),
0,
$e
));
}
// Exception already handled above, so don't throw an unhandled rejection here
return array();
});
}
/**
* @internal
*/
public function check($resolve, $reject)
{
$ip = \array_shift($this->connectQueue);
// start connection attempt and remember array position to later unset again
$this->connectionPromises[] = $this->attemptConnection($ip);
\end($this->connectionPromises);
$index = \key($this->connectionPromises);
$that = $this;
$that->connectionPromises[$index]->then(function ($connection) use ($that, $index, $resolve) {
unset($that->connectionPromises[$index]);
$that->cleanUp();
$resolve($connection);
}, function (\Exception $e) use ($that, $index, $ip, $resolve, $reject) {
unset($that->connectionPromises[$index]);
$that->failureCount++;
$message = \preg_replace('/^(Connection to [^ ]+)[&?]hostname=[^ &]+/', '$1', $e->getMessage());
if (\strpos($ip, ':') === false) {
$that->lastError4 = $message;
$that->lastErrorFamily = 4;
} else {
$that->lastError6 = $message;
$that->lastErrorFamily = 6;
}
// start next connection attempt immediately on error
if ($that->connectQueue) {
if ($that->nextAttemptTimer !== null) {
$that->loop->cancelTimer($that->nextAttemptTimer);
$that->nextAttemptTimer = null;
}
$that->check($resolve, $reject);
}
if ($that->hasBeenResolved() === false) {
return;
}
if ($that->ipsCount === $that->failureCount) {
$that->cleanUp();
$reject(new \RuntimeException(
$that->error(),
$e->getCode(),
$e
));
}
});
// Allow next connection attempt in 100ms: https://tools.ietf.org/html/rfc8305#section-5
// Only start timer when more IPs are queued or when DNS query is still pending (might add more IPs)
if ($this->nextAttemptTimer === null && (\count($this->connectQueue) > 0 || $this->resolved[Message::TYPE_A] === false || $this->resolved[Message::TYPE_AAAA] === false)) {
$this->nextAttemptTimer = $this->loop->addTimer(self::CONNECTION_ATTEMPT_DELAY, function () use ($that, $resolve, $reject) {
$that->nextAttemptTimer = null;
if ($that->connectQueue) {
$that->check($resolve, $reject);
}
});
}
}
/**
* @internal
*/
public function attemptConnection($ip)
{
$uri = Connector::uri($this->parts, $this->host, $ip);
return $this->connector->connect($uri);
}
/**
* @internal
*/
public function cleanUp()
{
// clear list of outstanding IPs to avoid creating new connections
$this->connectQueue = array();
// cancel pending connection attempts
foreach ($this->connectionPromises as $connectionPromise) {
if ($connectionPromise instanceof PromiseInterface && \method_exists($connectionPromise, 'cancel')) {
$connectionPromise->cancel();
}
}
// cancel pending DNS resolution (cancel IPv4 first in case it is awaiting IPv6 resolution delay)
foreach (\array_reverse($this->resolverPromises) as $resolverPromise) {
if ($resolverPromise instanceof PromiseInterface && \method_exists($resolverPromise, 'cancel')) {
$resolverPromise->cancel();
}
}
if ($this->nextAttemptTimer instanceof TimerInterface) {
$this->loop->cancelTimer($this->nextAttemptTimer);
$this->nextAttemptTimer = null;
}
}
/**
* @internal
*/
public function hasBeenResolved()
{
foreach ($this->resolved as $typeHasBeenResolved) {
if ($typeHasBeenResolved === false) {
return false;
}
}
return true;
}
/**
* Mixes an array of IP addresses into the connect queue in such a way they alternate when attempting to connect.
* The goal behind it is first attempt to connect to IPv6, then to IPv4, then to IPv6 again until one of those
* attempts succeeds.
*
* @link https://tools.ietf.org/html/rfc8305#section-4
*
* @internal
*/
public function mixIpsIntoConnectQueue(array $ips)
{
\shuffle($ips);
$this->ipsCount += \count($ips);
$connectQueueStash = $this->connectQueue;
$this->connectQueue = array();
while (\count($connectQueueStash) > 0 || \count($ips) > 0) {
if (\count($ips) > 0) {
$this->connectQueue[] = \array_shift($ips);
}
if (\count($connectQueueStash) > 0) {
$this->connectQueue[] = \array_shift($connectQueueStash);
}
}
}
/**
* @internal
* @return string
*/
public function error()
{
if ($this->lastError4 === $this->lastError6) {
$message = $this->lastError6;
} elseif ($this->lastErrorFamily === 6) {
$message = 'Last error for IPv6: ' . $this->lastError6 . '. Previous error for IPv4: ' . $this->lastError4;
} else {
$message = 'Last error for IPv4: ' . $this->lastError4 . '. Previous error for IPv6: ' . $this->lastError6;
}
if ($this->hasBeenResolved() && $this->ipsCount === 0) {
if ($this->lastError6 === $this->lastError4) {
$message = ' during DNS lookup: ' . $this->lastError6;
} else {
$message = ' during DNS lookup. ' . $message;
}
} else {
$message = ': ' . $message;
}
return 'Connection to ' . $this->uri . ' failed' . $message;
}
}