fix RDAP response error handling

src/Exceptions/RdapResponseException.php

@@ -0,0 +1,85 @@
+<?php
+
+declare(strict_types=1);
+
+namespace ArrayAccess\RdapClient\Exceptions;
+
+use RuntimeException;
+
+/**
+ * Thrown when the remote RDAP server returns an error response payload.
+ *
+ * The exception message is assembled from the `title` and `description`
+ * properties supplied by the server.  The exception code contains the
+ * numeric `errorCode` value.  The full decoded response is available via
+ * {@see getResponse()}.
+ */
+class RdapResponseException extends RuntimeException
+{
+    /**
+     * Full decoded payload returned by the server.
+     *
+     * Keeping the entire array allows callers to inspect additional
+     * properties without having to parse/reconstruct them from the message
+     * or code.
+     *
+     * @var array<string, mixed>
+     */
+    private array $response;
+
+    /**
+     * Construct from a previously prepared message.
+     *
+     * Use the named factory if possible.
+     *
+     * @param string                  $message  human readable description
+     * @param int                     $code     errorCode from the payload
+     * @param array<string, mixed>    $response original decoded response
+     * @param \Throwable|null         $previous previous exception
+     */
+    public function __construct(
+        string $message = "",
+        int $code = 0,
+        array $response = [],
+        ?\Throwable $previous = null
+    ) {
+        parent::__construct($message, $code, $previous);
+        $this->response = $response;
+    }
+
+    /**
+     * Create an exception instance from a decoded RDAP error response.
+     *
+     * @param array<string, mixed> $response
+     * @return self
+     */
+    public static function fromResponse(array $response): self
+    {
+        $code = isset($response['errorCode']) ? (int) $response['errorCode'] : 0;
+        $title = is_string($response['title'] ?? null) ? $response['title'] : '';
+        $description = '';
+        if (isset($response['description'])) {
+            if (is_string($response['description'])) {
+                $description = $response['description'];
+            } elseif (is_array($response['description'])) {
+                $description = implode(' ', $response['description']);
+            }
+        }
+
+        $parts = array_filter([$title, $description]);
+        $message = $parts ? implode(' - ', $parts) : 'RDAP error response';
+
+        return new self($message, $code, $response);
+    }
+
+    /**
+     * Get the raw response array that triggered the exception.
+     *
+     * @return array<string, mixed>
+     */
+    public function getResponse(): array
+    {
+        return $this->response;
+    }
+}
+

src/Interfaces/RdapRequestInterface.php

@@ -46,8 +46,11 @@ public function getTarget() : string;
 
     /**
      * Get RDAP Response
-     *
+     * 
      * @return RdapResponseInterface
+     *
+     * @throws \ArrayAccess\RdapClient\Exceptions\RdapRemoteRequestException
+     * @throws \ArrayAccess\RdapClient\Exceptions\RdapResponseException
      */
     public function getResponse() : RdapResponseInterface;
 

src/Response/Abstracts/AbstractResponse.php

@@ -5,6 +5,7 @@
 
 use ArrayAccess\RdapClient\Exceptions\InvalidDataTypeException;
 use ArrayAccess\RdapClient\Exceptions\MismatchProtocolBehaviorException;
+use ArrayAccess\RdapClient\Exceptions\RdapResponseException;
 use ArrayAccess\RdapClient\Interfaces\RdapProtocolInterface;
 use ArrayAccess\RdapClient\Interfaces\RdapRequestInterface;
 use ArrayAccess\RdapClient\Interfaces\RdapResponseInterface;
@@ -67,19 +68,42 @@ public function __construct(
     }
 
     /**
-     * Assert response
+     * Assert that the raw JSON response is valid and populate internal
+     * array representation.
+     *
      * @param string $responseJson
      * @return void
+     *
+     * @throws InvalidDataTypeException when the content cannot be decoded or
+     *         does not contain any of the required fields: objectClassName,
+     *         rdapConformance, or errorCode.
+     * @throws RdapResponseException  when the payload represents an error
+     *         response (``errorCode`` field present).  The returned exception
+     *         may be inspected via {@see RdapResponseException::getResponse()}
+     *         for the full payload; its message and code are derived from the
+     *         `title`/`description`/`errorCode` fields.
      */
     private function assertResponse(string $responseJson): void
     {
-        $responseJson = json_decode($responseJson, true);
-        if (!is_array($responseJson) || !is_string($responseJson['objectClassName']??null)) {
+        $decoded = json_decode($responseJson, true);
+
+        if (!is_array($decoded) ||
+            (!isset($decoded['objectClassName']) &&
+             !isset($decoded['rdapConformance']) &&
+             !isset($decoded['errorCode']))
+        ) {
             throw new InvalidDataTypeException(
                 'Response is not valid json content'
             );
         }
-        $this->responseArray = $responseJson;
+
+        if (isset($decoded['errorCode'])) {
+            // convert immediately into an exception; no need to validate
+            // required fields for error payloads.
+            throw RdapResponseException::fromResponse($decoded);
+        }
+
+        $this->responseArray = $decoded;
     }
 
     /**