Async SOCKS5 proxy connection times out in curl_cffi 0.14.0 (works in 0.13.0)

[pahixa]

Description

I’ve encountered a regression in curl_cffi 0.14.0 when using an asynchronous session with a SOCKS5 proxy.
The same code works correctly in curl_cffi 0.13.0, but in 0.14.0 the request always times out.

The issue happens when performing an async HTTPS request through a SOCKS5 proxy using AsyncSession.

Steps to Reproduce

import asyncio
import curl_cffi

TOR_SOCKS5 = 'socks5://192.168.1.30:9010'

async def get(session, url: str):
    response = await session.get(url)
    if response.ok:
        return response.text
    return 'ERROR'

async def main():
    session = curl_cffi.AsyncSession(
        proxies={
            'http': TOR_SOCKS5,
            'https': TOR_SOCKS5
        }
    )
    html = await get(session, 'https://httpbin.org/get')
    print(html)

if __name__ == '__main__':
    asyncio.run(main())

Actual Behavior

The request fails with a timeout error:

Traceback (most recent call last):
  File ".\env3.13\Lib\site-packages\curl_cffi\requests\session.py", line 1143, in request
    await task
curl_cffi.curl.CurlError: Failed to perform, curl: (28) Connection timed out after 30009 milliseconds.
See https://curl.se/libcurl/c/libcurl-errors.html for more details.

Expected Behavior

The request should complete successfully and return the response body, as it does in curl_cffi 0.13.0.

Comparison

✅ curl_cffi 0.13.0 → Works correctly
❌ curl_cffi 0.14.0 → Always times out

Environment

Python: 3.13
OS: Windows
Proxy type: SOCKS5
Async API: AsyncSession

Additional Notes

The SOCKS5 proxy is on my local network, accessible, and working correctly.
The same proxy and code work with curl_cffi 0.13.0.
This appears to be a regression introduced in 0.14.0.

[lawei123]

[BUG] SOCKS5 proxy regression in v0.14.0 - AsyncSession requests fail with curl error 97

Description

I encountered a regression when using SOCKS5 proxies with AsyncSession in curl_cffi 0.14.0. The same code works correctly in curl_cffi 0.13.0, but in 0.14.0, requests always fail with a proxy error.

Environment

• curl_cffi version: 0.14.0 (works in 0.13.0)
• Python version: 3.13/3.14
• OS: Windows 10/11

Steps to Reproduce

import asyncio
from curl_cffi.requests import AsyncSession

SOCKS5_PROXY = 'socks5://username:password@proxy_host:port'

async def main():
    async with AsyncSession() as session:
        response = await session.get(
            'https://httpbin.org/ip',
            proxy=SOCKS5_PROXY,
            timeout=30
        )
        print(response.text)

if __name__ == '__main__':
    asyncio.run(main())

Expected Behavior

Request should complete successfully through the SOCKS5 proxy (as it does in v0.13.0).

Actual Behavior

Request fails with error:

curl_cffi.curl.CurlError: Failed to perform, curl: (97) connection to proxy closed

Error code 97 is CURLE_PROXY.

Analysis

After investigating the source code, I found a potential cause in requests/utils.py around line 540-545:

if proxies:
    # Turn on proxy_credential_no_reuse
    c.setopt(CurlOpt.PROXY_CREDENTIAL_NO_REUSE, 1)

The PROXY_CREDENTIAL_NO_REUSE option appears to be newly added and may be incompatible with SOCKS5 proxies. This option is designed for HTTP proxy credential handling, but SOCKS5 uses a different authentication mechanism at the protocol level.

Additional Notes

• HTTP proxies work fine in 0.14.0
• Only SOCKS5 proxies are affected
• The issue occurs with both socks5:// and socks5h:// schemes
• Authenticated and non-authenticated SOCKS5 proxies both fail

Workaround

Downgrade to v0.13.0:

pip install curl-cffi==0.13.0

Suggested Fix

Consider one of the following:

1. Skip setting PROXY_CREDENTIAL_NO_REUSE for SOCKS proxies
2. Add a condition to check proxy type before applying this option

if proxies:
    # Only set for non-SOCKS proxies
    if proxy and not proxy.startswith("socks"):
        c.setopt(CurlOpt.PROXY_CREDENTIAL_NO_REUSE, 1)

[lexiforest]

@lawei123 I appreciate your effort in helping find the root cause. But, please be concise, do NOT dump the full output from LLM, only paste your verified key findings.

[pahixa]

I’ve tested the issue with version 0.15.0b3, and it seems to be working correctly 👍.
Thank you very much for your work.

[lexiforest]

But I haven't changed anything, I actually thought this is a valid issue. I will double confirm anyway.

[pahixa]

I notice quite a few changes in the "requests" folder, but I have no idea why. However, I can reproduce the issue with version 0.14.0, but not with version 0.15.0b3.