implemented DNS address resolving during intial routing table fetch cycle

Author: transistive

src/Common/DNSAddressResolver.php

@@ -31,11 +31,12 @@ public function getAddresses(string $host): iterable
         // as late as possible
         yield $host;
 
+        /** @var list<array{ip?: string|null}> $records */
         $records = dns_get_record($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_map(static fn (array $x) => $x['ip'] ?? '', $records);
             $records = array_filter($records, static fn (string $x) => $x !== '');
             yield from array_values(array_unique($records));
         }
@@ -46,9 +47,10 @@ public function getAddresses(string $host): iterable
      */
     private function tryReverseLookup(string $host): iterable
     {
+        /** @var list<array{target?: string|null}> $records */
         $records = dns_get_record($host.'.in-addr.arpa');
         if (count($records) !== 0) {
-            $records = array_map(static fn (array $x): string => $x['target'] ?? '', $records);
+            $records = array_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/Neo4j/Neo4jConnectionPool.php

@@ -24,6 +24,7 @@
 use Laudis\Neo4j\Bolt\BoltConnection;
 use Laudis\Neo4j\Bolt\BoltConnectionPool;
 use Laudis\Neo4j\Common\Uri;
+use Laudis\Neo4j\Contracts\AddressResolverInterface;
 use Laudis\Neo4j\Contracts\AuthenticateInterface;
 use Laudis\Neo4j\Contracts\ConnectionInterface;
 use Laudis\Neo4j\Contracts\ConnectionPoolInterface;
@@ -32,6 +33,8 @@
 use Laudis\Neo4j\Enum\RoutingRoles;
 use Psr\Http\Message\UriInterface;
 use function random_int;
+use RuntimeException;
+use function sprintf;
 use function str_starts_with;
 use function time;
 
@@ -52,13 +55,15 @@ final class Neo4jConnectionPool implements ConnectionPoolInterface
     private static array $routingCache = [];
     /** @psalm-readonly */
     private BoltConnectionPool $pool;
+    private AddressResolverInterface $resolver;
 
     /**
      * @psalm-mutation-free
      */
-    public function __construct(BoltConnectionPool $pool)
+    public function __construct(BoltConnectionPool $pool, AddressResolverInterface $resolver)
     {
         $this->pool = $pool;
+        $this->resolver = $resolver;
     }
 
     /**
@@ -73,10 +78,20 @@ public function acquire(
 
         $table = self::$routingCache[$key] ?? null;
         if ($table === null || $table->getTtl() < time()) {
-            $connection = $this->pool->acquire($uri, $authenticate, $config);
-            $table = $this->routingTable($connection, $config);
-            self::$routingCache[$key] = $table;
-            $connection->close();
+            $addresses = $this->resolver->getAddresses($uri->getHost());
+            $triedAddresses = [];
+            foreach ($addresses as $address) {
+                $triedAddresses[] = $address;
+                if ($this->pool->canConnect($uri->withHost($address), $authenticate)) {
+                    $connection = $this->pool->acquire($uri->withHost($address), $authenticate, $config);
+                    $table = $this->routingTable($connection, $config);
+                    self::$routingCache[$key] = $table;
+                    $connection->close();
+                    break;
+                }
+            }
+
+            throw new RuntimeException(sprintf('Cannot connect to address: "%s". Addresses tried: "%s"', $uri->getHost(), implode('", "', $triedAddresses)));
         }
 
         $server = $this->getNextServer($table, $config->getAccessMode()) ?? $uri;

src/Neo4j/Neo4jDriver.php

@@ -18,6 +18,7 @@
 use Laudis\Neo4j\Authentication\Authenticate;
 use Laudis\Neo4j\Bolt\BoltConnectionPool;
 use Laudis\Neo4j\Bolt\Session;
+use Laudis\Neo4j\Common\DNSAddressResolver;
 use Laudis\Neo4j\Common\Uri;
 use Laudis\Neo4j\Contracts\AuthenticateInterface;
 use Laudis\Neo4j\Contracts\DriverInterface;
@@ -35,7 +36,7 @@
  *
  * @implements DriverInterface<T>
  *
- * @psalm-import-type OGMResults from \Laudis\Neo4j\Formatter\OGMFormatter
+ * @psalm-import-type OGMResults from OGMFormatter
  */
 final class Neo4jDriver implements DriverInterface
 {
@@ -86,15 +87,15 @@ public static function create($uri, ?DriverConfiguration $configuration = null,
             return new self(
                 $uri,
                 $authenticate ?? Authenticate::fromUrl($uri),
-                new Neo4jConnectionPool(new BoltConnectionPool($configuration)),
+                new Neo4jConnectionPool(new BoltConnectionPool($configuration), new DNSAddressResolver()),
                 $formatter,
             );
         }
 
         return new self(
             $uri,
             $authenticate ?? Authenticate::fromUrl($uri),
-            new Neo4jConnectionPool(new BoltConnectionPool($configuration)),
+            new Neo4jConnectionPool(new BoltConnectionPool($configuration), new DNSAddressResolver()),
             OGMFormatter::create(),
         );
     }