implemented address resolvers

Author: transistive

src/Common/DNSAddressResolver.php

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+<?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;
+
+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;
+
+        $records = dns_get_record($host, DNS_A | DNS_AAAA);
+        if (count($records) === 0) {
+            yield from $this->tryReverseLookup($host);
+        } else {
+            $records = array_map(static fn (array $x): string => $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
+    {
+        $records = dns_get_record($host.'.in-addr.arpa');
+        if (count($records) !== 0) {
+            $records = array_map(static fn (array $x): string => $x['target'] ?? '', $records);
+            $records = array_filter($records, static fn (string $x) => $x !== '');
+            yield from array_values(array_unique($records));
+        }
+    }
+}

src/Contracts/AddressResolverInterface.php

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+<?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;
+}

tests/Unit/DNSAddressResolverTest.php

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+<?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')]);
+    }
+}