No Server Response when using Rotating Proxies

[FuckingToasters]

Overview
Below you'll see a bug report about two different issues which both are the result of using a proxy.

First Issue
When requesting the Discord API with proxies using httpx.Client() after some time this issue happen:

Traceback (most recent call last):
  File "/usr/local/lib/python3.9/dist-packages/httpx/_transports/default.py", line 60, in map_httpcore_exceptions
    yield
  File "/usr/local/lib/python3.9/dist-packages/httpx/_transports/default.py", line 218, in handle_request
    resp = self._pool.handle_request(req)
  File "/usr/local/lib/python3.9/dist-packages/httpcore/_sync/connection_pool.py", line 253, in handle_request
    raise exc
  File "/usr/local/lib/python3.9/dist-packages/httpcore/_sync/connection_pool.py", line 237, in handle_request
    response = connection.handle_request(request)
  File "/usr/local/lib/python3.9/dist-packages/httpcore/_sync/http_proxy.py", line 267, in handle_request
    raise ProxyError(msg)
httpcore.ProxyError: 502 Bad Gateway

The above exception was the direct cause of the following exception:

Traceback (most recent call last):
  File "/usr/lib/python3.9/threading.py", line 954, in _bootstrap_inner
    self.run()
  File "/usr/lib/python3.9/threading.py", line 892, in run
    self._target(*self._args, **self._kwargs)
  File "/home/admin/bot/main.py", line 170, in verify
    VERIFYCODE = waitsms()
  File "/home/admin/bot/main.py", line 155, in waitsms
    discordresponse = client.post(discordurl, json=data, headers=HEADERS)
  File "/usr/local/lib/python3.9/dist-packages/httpx/_client.py", line 1130, in post
    return self.request(
  File "/usr/local/lib/python3.9/dist-packages/httpx/_client.py", line 815, in request
    return self.send(request, auth=auth, follow_redirects=follow_redirects)
  File "/usr/local/lib/python3.9/dist-packages/httpx/_client.py", line 902, in send
    response = self._send_handling_auth(
  File "/usr/local/lib/python3.9/dist-packages/httpx/_client.py", line 930, in _send_handling_auth
    response = self._send_handling_redirects(
  File "/usr/local/lib/python3.9/dist-packages/httpx/_client.py", line 967, in _send_handling_redirects
    response = self._send_single_request(request)
  File "/usr/local/lib/python3.9/dist-packages/httpx/_client.py", line 1003, in _send_single_request
    response = transport.handle_request(request)
  File "/usr/local/lib/python3.9/dist-packages/httpx/_transports/default.py", line 218, in handle_request
    resp = self._pool.handle_request(req)
  File "/usr/lib/python3.9/contextlib.py", line 135, in __exit__
    self.gen.throw(type, value, traceback)
  File "/usr/local/lib/python3.9/dist-packages/httpx/_transports/default.py", line 77, in map_httpcore_exceptions
    raise mapped_exc(message) from exc
httpx.ProxyError: 502 Bad Gateway

Second Issue
Sometimes after some time, instead of the 502 error above, another issue appear:
Server closed without sending response`
(Currently i don't have the full Traceback for this issue ready to include here)

To Reproduce
Do a http request to discord.com while using proxies:

    data1 = {"foo": "bar"}
    with httpx.Client(headers=HEADERS, timeout=timeout, proxies=proxyauth if proxytype != "" else None) as client:
        resp2 = client.post("https://discord.com/api/v9/users/@me", json=data1)
    lock.acquire()
    if resp2.status_code == 204: pystyle.Write.Print("\t[+] Successfully requested api!\n", pystyle.Colors.green, interval=0)
    lock.release()

Expected behavior
In case you use a proxy, it should request the api as usual without any issue.

[tomchristie]

It's not obvious to me how best to try to help with resolving this.

• Is this issue occurring consistently?
• Are you able to try with requests as an alternative? (To determine if this is a client-specific issue or not.)

[FuckingToasters]

It's not obvious to me how best to try to help with resolving this.

• Is this issue occurring consistently?
• Are you able to try with requests as an alternative? (To determine if this is a client-specific issue or not.)

It seems that the issue is caused by rotating proxies. When choosing sticky ones with 30 seconds - 1 minute stickiness the issue don't happen that often. However it still would be nice to be able to use rotating proxies.

[tomchristie]

• Can you provide an example of how to setup and test this?
• Are you able to confirm if the behaviour is differs with an alternate client? (Eg. requests, urllib3, or aiohttp?)

[imchao9]

@tomchristie I also have this problem.

export https_proxy=http://127.0.0.1:7890 http_proxy=http://127.0.0.1:7890 all_proxy=socks5://127.0.0.1:7890

If I export the proxy and run this test.py file, I will get 502, but if I do not use proxy, then I get 200, here is my file:

import httpx
r = httpx.get('http://localhost:6333')
print(r.status_code)

Can you help me fix this problem?

[tomchristie]

To start debugging where the issue is, I'd suggest the same starting point as here... #2368 (reply in thread)

There's a bunch of different reasons why you might get the 502 response code, which could be to do with the client, the proxy, or the server. So the best first place to try to dig into that is trying different clients.