merged connection resolver into main

Author: transistive

src/Common/DNSAddressResolver.php

@@ -0,0 +1,69 @@
+<?php
+
+/*
+ * This file is part of the Neo4j PHP Client and Driver package.
+ *
+ * (c) Nagels <https://nagels.tech>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace Laudis\Neo4j\Common;
+
+use function array_filter;
+use function array_map;
+use function array_unique;
+use function array_values;
+use const DNS_A;
+use const DNS_AAAA;
+use function dns_get_record;
+use Laudis\Neo4j\Contracts\AddressResolverInterface;
+use Throwable;
+
+class DNSAddressResolver implements AddressResolverInterface
+{
+    /**
+     * @return iterable<string>
+     */
+    public function getAddresses(string $host): iterable
+    {
+        // By using the generator pattern we make sure to call the heavy DNS IO operations
+        // as late as possible
+        yield $host;
+
+        try {
+            /** @var list<array{ip?: string|null}> $records */
+            $records = dns_get_record($host, DNS_A | DNS_AAAA);
+        } catch (Throwable $e) {
+            $records = []; // Failed DNS queries should not halt execution
+        }
+
+        if (count($records) === 0) {
+            yield from $this->tryReverseLookup($host);
+        } else {
+            $records = array_map(static fn (array $x) => $x['ip'] ?? '', $records);
+            $records = array_filter($records, static fn (string $x) => $x !== '');
+            yield from array_values(array_unique($records));
+        }
+    }
+
+    /**
+     * @return iterable<string>
+     */
+    private function tryReverseLookup(string $host): iterable
+    {
+        try {
+            /** @var list<array{target?: string|null}> $records */
+            $records = dns_get_record($host.'.in-addr.arpa');
+        } catch (Throwable $e) {
+            $records = []; // Failed DNS queries should not halt execution
+        }
+
+        if (count($records) !== 0) {
+            $records = array_map(static fn (array $x) => $x['target'] ?? '', $records);
+            $records = array_filter($records, static fn (string $x) => $x !== '');
+            yield from array_values(array_unique($records));
+        }
+    }
+}

src/Contracts/AddressResolverInterface.php

@@ -0,0 +1,22 @@
+<?php
+
+/*
+ * This file is part of the Neo4j PHP Client and Driver package.
+ *
+ * (c) Nagels <https://nagels.tech>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace Laudis\Neo4j\Contracts;
+
+interface AddressResolverInterface
+{
+    /**
+     * Returns the addresses.
+     *
+     * @return iterable<string>
+     */
+    public function getAddresses(string $host): iterable;
+}

src/Neo4j/Neo4jConnectionPool.php

@@ -13,6 +13,8 @@
 
 namespace Laudis\Neo4j\Neo4j;
 
+use Laudis\Neo4j\Contracts\AddressResolverInterface;
+use RuntimeException;
 use function array_slice;
 use function array_unique;
 use Bolt\error\MessageException;
@@ -41,6 +43,8 @@
 use Laudis\Neo4j\Databags\SessionConfiguration;
 use Laudis\Neo4j\Enum\AccessMode;
 use Laudis\Neo4j\Enum\RoutingRoles;
+use function implode;
+use function sprintf;
 use const PHP_INT_MAX;
 use Psr\Http\Message\UriInterface;
 use Psr\SimpleCache\CacheInterface;
@@ -58,6 +62,9 @@
  */
 final class Neo4jConnectionPool implements ConnectionPoolInterface
 {
+    /** @psalm-readonly */
+    private BoltConnectionPool $pool;
+    private AddressResolverInterface $resolver;
     /** @var array<string, ConnectionPool> */
     private static array $pools = [];
     private SemaphoreInterface $semaphore;
@@ -119,13 +126,25 @@ public function acquire(SessionConfiguration $config): Generator
 
         /** @var RoutingTable|null */
         $table = $this->cache->get($key, null);
+        $triedAddresses = [];
+
         if ($table == null) {
-            $pool = $this->createOrGetPool($this->data->getUri());
-            /** @var BoltConnection $connection */
-            $connection = GeneratorHelper::getReturnFromGenerator($pool->acquire($config));
-            $table = $this->routingTable($connection, $config);
-            $this->cache->set($key, $table, $table->getTtl());
-            $pool->release($connection);
+            $addresses = $this->resolver->getAddresses($this->data->getUri());
+            foreach ($addresses as $address) {
+                $triedAddresses[] = $address;
+                $pool = $this->createOrGetPool($address);
+                if ($this->pool->canConnect($this->data->getUri()->withHost($address), $this->data->getAuth())) {
+                    /** @var BoltConnection $connection */
+                    $connection = GeneratorHelper::getReturnFromGenerator($pool->acquire($config));
+                    $table      = $this->routingTable($connection, $config);
+                    $this->cache->set($key, $table, $table->getTtl());
+                    $pool->release($connection);
+                }
+            }
+        }
+
+        if ($table === null) {
+            throw new RuntimeException(sprintf('Cannot connect to host: "%s". Hosts tried: "%s"', $this->data->getUri()->getHost(), implode('", "', $triedAddresses)));
         }
 
         $server = $this->getNextServer($table, $config->getAccessMode()) ?? $this->data->getUri();

src/Neo4j/Neo4jDriver.php

@@ -18,6 +18,7 @@
 use Laudis\Neo4j\Authentication\Authenticate;
 use Laudis\Neo4j\Bolt\Session;
 use Laudis\Neo4j\Common\GeneratorHelper;
+use Laudis\Neo4j\Common\DNSAddressResolver;
 use Laudis\Neo4j\Common\Uri;
 use Laudis\Neo4j\Contracts\AuthenticateInterface;
 use Laudis\Neo4j\Contracts\DriverInterface;

tests/Unit/DNSAddressResolverTest.php

@@ -0,0 +1,49 @@
+<?php
+
+/*
+ * This file is part of the Neo4j PHP Client and Driver package.
+ *
+ * (c) Nagels <https://nagels.tech>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace Laudis\Neo4j\Tests\Unit;
+
+use Laudis\Neo4j\Common\DNSAddressResolver;
+use PHPUnit\Framework\TestCase;
+
+class DNSAddressResolverTest extends TestCase
+{
+    private DNSAddressResolver $resolver;
+
+    protected function setUp(): void
+    {
+        parent::setUp();
+        $this->resolver = new DNSAddressResolver();
+    }
+
+    public function testResolverGhlenDotCom(): void
+    {
+        $records = [...$this->resolver->getAddresses('test.ghlen.com')];
+
+        $this->assertEqualsCanonicalizing(['test.ghlen.com', '123.123.123.123', '123.123.123.124'], $records);
+        $this->assertNotEmpty($records);
+        $this->assertEquals('test.ghlen.com', $records[0]);
+    }
+
+    public function testResolverGoogleDotComReverse(): void
+    {
+        $records = [...$this->resolver->getAddresses('8.8.8.8')];
+
+        $this->assertEqualsCanonicalizing(['8.8.8.8', 'dns.google'], $records);
+        $this->assertNotEmpty($records);
+        $this->assertEquals('8.8.8.8', $records[0]);
+    }
+
+    public function testBogus(): void
+    {
+        $this->assertEquals(['bogus'], [...$this->resolver->getAddresses('bogus')]);
+    }
+}