Throw exception on `null` results

[veewee]

Feature Request

Q	A
New Feature	yes
RFC	no
BC Break	no

Summary

Ext-soap returns null on various errorneous situations:

• timeout reached
• encoding failed
• decoding failed
• HTML result instead of XML
• On invalid HTTP codes if the payload is HTML
• ...

This null result can be handled by the AbusedClient and result in an exception instead - which makes more sense.

To investigate:

• Can we find out "what" goes wrong that results in null?
• Is null always an indication for errors? Or are there situations that a soap service doesn't return a response?

Context:

• How to throw SoapException for http errors? phpro/soap-client#404
• Incorrect work with SoapClient::__doRequest() #3

[veewee]

Investigated a bit deeper.
Connection timeouts can be grabbed by adding an error handler:

Example code

namespace Soap\ExtSoapEngine\ErrorHandling;

use Soap\ExtSoapEngine\Exception\RequestException;

/**
 * @psalm-internal
 */
final class ExtSoapErrorHandler
{
    /**
     * @template T
     *
     * @param (callable(): T) $fun
     *
     * @return array{0: T, 1: ?string}
     *
     * @psalm-suppress MissingThrowsDocblock
     */
    public function __invoke(callable $fun): array
    {
        $lastMessage = null;
        /** @psalm-suppress InvalidArgument */
        set_error_handler(static function (int $_type, string $message) use (&$lastMessage) {
            $lastMessage = $message;
        });

        try {
            $value = $fun();

            /** @var array{0: T, 1: ?string} $result */
            $result = [$value, $lastMessage];

            return $result;
        } finally {
            restore_error_handler();
        }
    }

    /**
     * @template T
     *
     * @param (callable(): T) $fun
     *
     * @return T
     */
    public static function handleInternalErrors(callable $fun)
    {
        [$result, $lastMessage] = (new self)($fun);

        if ($lastMessage) {
            throw RequestException::internalSoapError($lastMessage);
        }

        return $result;
    }
}

In the AbusedClient:

    public function doActualRequest(
        string $request,
        string $location,
        string $action,
        int $version,
        bool $oneWay = false
    ): string {
        $this->__last_request = $request;
        $this->__last_response = (string) ExtSoapErrorHandler::handleInternalErrors(
            fn () => parent::__doRequest($request, $location, $action, $version, $oneWay)
        );

        return $this->__last_response;
    }

However, invalid encoding / decoding errors can't really be caught - or at least to my knowledge.
The only way might be to parse the last response headers and check for status code 400-500 based on the status code:

  private string $lastResponseHeaders =>
  string(215) "HTTP/1.1 400 Bad Request

I'm still not sure if NULL always means that there was an error. Possibly could a $oneWay SOAP request also result in a NULL response - which might not be an error.