Fix cancelling happy eyeballs when IPv6 resolution is pending

src/HappyEyeBallsConnectionBuilder.php

@@ -65,9 +65,8 @@ public function __construct(LoopInterface $loop, ConnectorInterface $connector,
 
  public function connect()
  {
- $timer = null;
  $that = $this;
- return new Promise\Promise(function ($resolve, $reject) use ($that, &$timer) {
+ return new Promise\Promise(function ($resolve, $reject) use ($that) {
  $lookupResolve = function ($type) use ($that, $resolve, $reject) {
  return function (array $ips) use ($that, $type, $resolve, $reject) {
  unset($that->resolverPromises[$type]);
@@ -83,36 +82,36 @@ public function connect()
  };
 
  $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, &$timer) {
+ $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();
+ $deferred = new Promise\Deferred(function () use (&$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) {
+ $that->resolverPromises[Message::TYPE_AAAA]->then(function () use ($that, $timer, $deferred, &$ips) {
  $that->loop->cancelTimer($timer);
  $deferred->resolve($ips);
  });
 
  return $deferred->promise();
  })->then($lookupResolve(Message::TYPE_A));
- }, function ($_, $reject) use ($that, &$timer) {
+ }, function ($_, $reject) use ($that) {
  $reject(new \RuntimeException(
  'Connection to ' . $that->uri . ' cancelled' . (!$that->connectionPromises ? ' during DNS lookup' : '') . ' (ECONNABORTED)',
  \defined('SOCKET_ECONNABORTED') ? \SOCKET_ECONNABORTED : 103
  ));
  $_ = $reject = null;
 
  $that->cleanUp();
- if ($timer instanceof TimerInterface) {
- $that->loop->cancelTimer($timer);
- }
  });
  }
 
@@ -247,13 +246,15 @@ 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();
  }
  }
 
- foreach ($this->resolverPromises as $resolverPromise) {
+ // cancel pending DNS resolution (cancel IPv4 first in case it is awaiting IPv6 resolution delay)
+ foreach (\array_reverse($this->resolverPromises) as $resolverPromise) {
  if ($resolverPromise instanceof PromiseInterface && \method_exists($resolverPromise, 'cancel')) {
  $resolverPromise->cancel();
  }

tests/HappyEyeBallsConnectionBuilderTest.php

@@ -695,7 +695,9 @@ public function testCancelConnectWillRejectPromiseAndCancelPendingIpv6LookupAndC
  array('reactphp.org', Message::TYPE_AAAA),
  array('reactphp.org', Message::TYPE_A)
  )->willReturnOnConsecutiveCalls(
- new Promise(function () { }, $this->expectCallableOnce()),
+ new Promise(function () { }, function () {
+ throw new \RuntimeException('DNS cancelled');
+ }),
  \React\Promise\resolve(array('127.0.0.1'))
  );