QNetworkReply fails with socket timeout for URLs that otherwise work

  • Recently I've started looking into the QtNetwork module since it's part of a project I'm currently working on at work.

    I checked the example provided in the Qt documentation. By default it has the https://www.qt.io URL for testing the capabilities of the application. It works just fine.

    Then I moved to something that is closer to my own task. Basically I need to request data using HTTP GET requests (basically what QNetworkAccessManager::get(...) does). These requests also include parameters. So I looked online for free HTTP GET request services and found http://httpbin.org/xml (gives me some XML output that is similar to what I need to handle; other entpoints are available too) and later https://postman-echo.com/get.

    In the demo application as well as my own (basically the same but for console) the first one leads to a socket timeout while the second one works without any issues.

    Further both URLs work without a problem in Firefox (and its Http Requester add-on) and curl (I used curl --request GET --url "URL here"). This problem applies to many other URLs I've tried (that include parameters) including the one I'm supposed to use (I can't post it here).

    I haven't worked with the QtNetwork module for a long time but even when I used it I don't recall having such a problem. Same applies for using HTTP requests. Am I missing something here? I've even tried to call these URLs with Python's urllib

    import urllib.request
    res = urllib.request.urlopen("http://httpbin.org/get").read().decode("utf-8") 
    import xml.etree.ElementTree as ET
    doc = ET.fromstring(res)

    and it just works.

  • I forgot to mention that I'm behind a proxy. A colleague of mine tried adding s to the http so that the proxy and its caching is circumvented and it worked all of a sudden. Setting the raw header didn't help either. So basically for the target system (after it gets installed in the final product) I can work with the URL but on my PC behind the proxy I'm screwed and have to convert every single URL to https even if it's not.

    My colleague found that QNetworkProxyFactory::setUseSystemConfiguration(true) does the trick in a very neutral way and it works now.

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