Invalid label PDF file in Firefox, not in Chrome

[jelledruut]

SDK version

9.0.0

PHP version

8.3

What went wrong?

We're using Firefox for our internal shipping application, but it can't seem to open PostNL MyParcel PDF files, due to an Invalid stream error.

It happens both with downloadPdfOfLabels and manually saving the contents from getLabelPdf (downloadPdfOfLabels also uses label_pdf though)

The thing is, the PDF's are displayed just fine in Chrome, but not in Firefox. We're storing/printing/opening a variety of labels from different sources, but I haven't experienced this issue before.

Warning: Invalid stream: "FormatError: Unknown compression method in flate stream: 50, 32" [pdf.worker.mjs:323:13](resource://pdf.js/build/pdf.worker.mjs)

        // Please fill in those variables
        $person = ''; 
        $street = '';
        $number = '';
        $numberAdditional = '';
        $postalCode = '';
        $city = '';
        $countryCode = 'NL';

        $consignment = (\MyParcelNL\Sdk\Factory\ConsignmentFactory::createByCarrierName('postnl'))
            ->setApiKey(config('services.my_parcel.api_key'))
            ->setCountry($countryCode)
            ->setPerson($person)
            ->setStreet($street)
            ->setNumber($number)
            ->setStreetAdditionalInfo($numberAdditional)
            ->setPostalCode($postalCode)
            ->setCity($city);

        $consignments = (new \MyParcelNL\Sdk\Helper\MyParcelCollection())
            ->addConsignment($consignment)
            ->setPdfOfLabels(false); // A6

        $consignments->downloadPdfOfLabels();

Part of our actual code:

        $consignment = (ConsignmentFactory::createByCarrierName('postnl'))
            ->setApiKey(config('services.my_parcel.api_key'))
            ->setCountry($address->countryCode)
            ->setPerson($address->getFullName())
            ->setStreet($address->street)
            ->setNumber($address->number)
            ->setPostalCode($address->postalCode)
            ->setCity($address->city);

        // other code

        $consignments = (new MyParcelCollection())
            ->addConsignment($consignment)
            ->setPdfOfLabels(false); // A6

        /** @var AbstractConsignment $consignment */
        $consignment = $consignments->first();

        $trackingId = $consignment->getBarcode();
        $trackingUrl = $consignment->getBarcodeUrl(
            barcode: $trackingId,
            postalCode: $address->postalCode,
            countryCode: $address->countryCode,
        );

        return new ShippingLabel(
            trackingId: $trackingId,
            trackingUrl: $trackingUrl,
            pdfContents: $consignments->getLabelPdf(),
        );

Reproduction steps

1. Create a 'postnl' label through the code provided
2. Store the contents to a PDF file (e.g. file_put_contents('file.pdf', $consignments->getLabelPdf());
   2.1. Alternatively, use downloadPdfOfLabels for the same result
3. Open the PDF in Firefox
4. Firefox displays a blank PDF and throws an error in the dev tools console

Relevant log output

Additional context

We're using the most recent stable version of Firefox.

[jelledruut]

Ok so I tried manually requesting the PDF contents, so that FpdfMerge is not used, since we're always creating just a single label. And now the PDF is fine. So FpdfMerge seems to be the issue.

We're going to request them manually, but it would be great if this could be looked into.

Sample code that results in valid PDFs:

$consignment = (ConsignmentFactory::createByCarrierName('postnl'))
    ->setApiKey(config('services.my_parcel.api_key'))
    ->setCountry($countryCode)
    ->setPerson($person)
    ->setStreet($street)
    ->setNumber($number)
    ->setStreetAdditionalInfo($numberAdditional)
    ->setPostalCode($postalCode)
    ->setCity($city);

$consignments = (new MyParcelCollection())
    ->addConsignment($consignment)
    ->setPdfOfLabels(false); // A6

/** @var AbstractConsignment $consignment */
$consignment = $consignments->first();

$request = (new MyParcelRequest())
    ->setUserAgents($consignments->getUserAgent())
    ->setRequestParameters(
        apiKey: config('services.my_parcel.api_key'),
        body: $consignment->getConsignmentId() . '/' . $consignments->getRequestBody(),
        requestHeaders: MyParcelRequest::HEADER_ACCEPT_APPLICATION_PDF
    )
    ->sendRequest('GET', MyParcelRequest::REQUEST_TYPE_RETRIEVE_LABEL);

$result = $request->getResult();
if (
    ! is_string($result) ||
    ! preg_match('/^%PDF-1./', $result)
) {
    throw new \RuntimeException('Unexpected result');
}

file_put_contents(__DIR__ . '/test.pdf', $result);

[ymschaap]

After upgrading the package version, I'm running into the same issue.

[ymschaap]

I found the issue in the "FPDF" package - which imho is outdated unversioned and should not be used.

In the file FpdfMerge.php

  '/Type' => array(self::TYPE_TOKEN, '/Calalog'),

Calalog is a typo, and should be Calalog.

  //$buf = gzcompress($buf); TODO Joeri
  $dico['/Filter'] = array(self::TYPE_TOKEN, '/FlateDecode');

Is commented out (with an todo) but on the next line, it does flag as compressed. Also uncomment that second line.

For me this fixed the white labels, it would be nice to implement in the next version (or move away from FPDF).

[ymschaap]

I found a more recent version of fpdf here: https://github.com/setasign/fpdf, which has composer support.