QNetworkReply and QNetworAccessManager don't emit `finished` signal

xueqli

Hello,

I am trying to access an API which requires authentication, but when I set incorrect bearer token in the header both reply and network manager don't emit finished signal.
reply.isFinished() -> False
reply.error() -> NoError
reply.isRunning() -> True

If I remove token, then everything's fine and request fails with an error ContentAccessDenied: 201
If I set the correct token, then everything's working too
If I use the requests library with an incorrect token, then everything works: the answer has status code 401

The only thing that I came up with is using setTransferTimeout and waiting for the request to abort after this timeout

Here is an example of what I'm trying to run:

import sys

from PyQt6.QtCore import QUrl
from PyQt6.QtNetwork import QNetworkReply
from PyQt6.QtNetwork import QNetworkRequest
from PyQt6.QtNetwork import QNetworkAccessManager
from PyQt6.QtWidgets import QApplication


class ApiAccess:
    def __init__(self) -> None:
        self.manager = QNetworkAccessManager()
        self.manager.finished.connect(self.on_manager_finished)

        self.reply = None
        self.token = "123"

    def get(self, url: QUrl) -> None:
        request = QNetworkRequest(url)
        request.setRawHeader(b"Authorization", f"Bearer {self.token}".encode("utf-8"))
        request.setRawHeader(b"User-Agent", b"MyUserAgent")

        self.reply = self.manager.get(request)
        self.reply.finished.connect(self.on_reply_finished)
        self.reply.errorOccurred.connect(self.on_reply_error)

    def on_manager_finished(self, reply: QNetworkReply) -> None:
        print(reply)

    def on_reply_error(self, error: QNetworkReply.NetworkError) -> None:
        print(error)

    def on_reply_finished(self) -> None:
        data = self.reply.readAll().data()
        print(data)


def main():
    app = QApplication(sys.argv)

    api = ApiAccess()
    url = QUrl("https://api.someresource.com/path?query")
    api.get(url)

    return app.exec()


if __name__ == "__main__":
    raise SystemExit(main())

Is this a bug, or am I missing something? (PyQt6 6.6.1)

xueqli

i found out that apparently it has nothing to do with either contents or headers,
and the real reason is: the request was using HTTP/2 protocol
disabling HTTP/2 (request.setAttribute(request.Attribute.Http2AllowedAttribute, False)) solves my problem

but what's wrong with HTTP/2 is yet to be figured out

SGaist

Hi and welcome to devnet,

Did you already check the traffic with Wireshark to see the answer you are getting back from the server ?

Ronel_qtmaster

@xueqli in the url, change https to http and try again

xueqli

@SGaist Hi! What exactly am I supposed to look at in the traffic?
It looks like the server does respond to the requests
Here are some screens:

xueqli

@Ronel_qtmaster unfortunately, that didn't help

xueqli

For now I'm pretty sure that this is related to QTBUG-122281, because when I connect the metaDataChanged signal and look into reply's headers, they contain information about the invalid token, but nothing happens after

SGaist

@xueqli just to rule out the obvious, you have the same issue if you send requests to a different service ?

Is there one that is accessible that you can share for testing purposes so we can test it ?

xueqli

@SGaist hmm, I haven't encountered this issue for other services
At first I thought that the problem is with www-authenticate header field
So I found the API which also sends it (https://registry-1.docker.io/v2/_catalog, for example), and it works fine (my API sends some other attributes in www-authenticate header, but they are all valid)

The other difference I noticed, my API doesn't send any content (answer.content == b''), and all API I've tried so far send a non-empty error message, so maybe my problem lies here

xueqli

i don't know, looks like it stuck somewhere in the QIODevice::read?

(Pdb) self.reply.isOpen()
True
(Pdb) self.reply.bytesAvailable()
0
(Pdb) self.reply.read(1000)
b''
(Pdb) self.reply.read(1000)
b''
(Pdb) self.reply.read(1000)
b''
(Pdb) self.reply.read(1000)
b''
(Pdb) self.reply.read(1000)
b''
(Pdb) self.reply.close()
got reply error! NetworkError.OperationCanceledError
download progress! received=0 total=0
manager finished!
QIODevice::read (QNetworkReplyHttpImpl): device not open
reply finished! b''

and after i manually close reply it says, that device is not open and emits all the signals i want it to emit

i also made up an http server, which sends similar headers and empty content and it magically works! (but with this "manual close" it has some different output:

self.reply.isOpen()=True
got reply error! NetworkError.OperationCanceledError
download progress! received=0 total=0
manager finished!
QIODevice::read (QNetworkReplyHttpImpl): device not open
reply finished! b''
QNetworkReplyImplPrivate::error: Internal problem, this method must only be called once.

i have no ideas. think i probably should give up and create workarounds

SGaist

@xueqli before working around, please open a ticket on the bug report system with your findings. It seems you have a valid case to make.

xueqli

i found out that apparently it has nothing to do with either contents or headers,
and the real reason is: the request was using HTTP/2 protocol
disabling HTTP/2 (request.setAttribute(request.Attribute.Http2AllowedAttribute, False)) solves my problem

but what's wrong with HTTP/2 is yet to be figured out

SGaist

@xueqli Nice catch !

I would still recommend opening a ticket.

xueqli

@SGaist yea, i did: https://bugreports.qt.io/browse/QTBUG-123891
(and turned out both HTTP/2 and www-authenticate headers are required to reproduce this)

SGaist

Thanks for the link and thorough spelunking !

Since you have a Python reproducer, you should add it to the bug report, it will make things easier for developers to reproduce :-)