HttpURLConnection PUT to Google Cloud Storage giving error 403

Question

I tried to upload a file to Google Cloud Storage using XML API. I have the right GoogleAccessId, expiry date and signature generated for each upload. The strange thing is that I can PUT file using Postman (application for Chrome), so I'm sure that the URL is ok. I just cannot PUT it using my Android Java program (it returns to me 403 error). The source code performing upload is here (it base on this one: https://cloud.google.com/storage/docs/access-control#Signing-Strings):

    URL url;
    HttpURLConnection connection;

    try {
        url = new URL("http://google-testbucket.storage.googleapis.com/testdata.txt?GoogleAccessId=1234567890123@developer.gserviceaccount.com&Expires=1331155464&Signature=BClz9e4UA2MRRDX62TPd8sNpUCxVsqUDG3YGPWvPcwN%2BmWBPqwgUYcOSszCPlgWREeF7oPGowkeKk7J4WApzkzxERdOQmAdrvshKSzUHg8Jqp1lw9tbiJfE2ExdOOIoJVmGLoDeAGnfzCd4fTsWcLbal9sFpqXsQI8IQi1493mw%3D");
        connection = (HttpURLConnection) url.openConnection();
        connection.setDoOutput(true);
        connection.setRequestMethod("PUT");

        OutputStreamWriter out = new OutputStreamWriter(connection.getOutputStream());
        out.write("Test");
        out.close();

        Log.i("TAG", "PUT Response code: " + connection.getResponseCode());

    } catch (MalformedURLException e) {
        e.printStackTrace();
        Log.e("TAG", "MalformedURLException");
    } catch (ProtocolException e) {
        e.printStackTrace();
        Log.e("TAG", "ProtocolException");
    } catch (IOException e) {
        e.printStackTrace();
        Log.e("TAG", "IOException");
    }

Documentation for PUT Object: https://cloud.google.com/storage/docs/xml-api/put-object-upload

Can anybody look into this problem and give me hints what might went wrong with this one?

Answer 1

I just figured out that HttpURLConnection adds Content-Type header with value application/x-www-form-urlencoded by itself. I've done it using HTTP sniffer on my android emulator.

This auto-added header caused signature mismatch. After I changed the code on the server-side to allow requests with Content-Type: application/x-www-form-urlencoded it generates the right signature and it works fine.

Thank you @morpheus05 for your commitment.