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aiohttp client does not support ipv6 addresses #559

mx2323 opened this Issue Oct 8, 2015 · 6 comments


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mx2323 commented Oct 8, 2015

attempting to get a webpage from an ipv6 address doesnt appear to work in aiohttp 0.17.4

when i run the ipv6 address through curl it works.

i also tried the ipv4 address through the aiohttp client and that worked as well.

http://[::1]:9001/foo fails with the following exception
socket.gaierror: [Errno -9] Address family for hostname not supported

 Cannot connect to host ::1:9001 ssl:False http://[::1]:9001/foo
Traceback (most recent call last):
  File "/usr/local/lib/python3.4/dist-packages/aiohttp/", line 571, in _create_connection
    server_hostname=hinfo['hostname'] if sslcontext else None)
  File "/usr/lib/python3.4/asyncio/", line 581, in create_connection
    infos = f1.result()
  File "/usr/lib/python3.4/asyncio/", line 275, in result
    raise self._exception
  File "/usr/lib/python3.4/concurrent/futures/", line 54, in run
    result = self.fn(*self.args, **self.kwargs)
  File "/usr/lib/python3.4/", line 533, in getaddrinfo
    for res in _socket.getaddrinfo(host, port, family, type, proto, flags):
socket.gaierror: [Errno -9] **Address family for hostname not supported**

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

Traceback (most recent call last):
  File "/usr/local/lib/python3.4/dist-packages/aiohttp/", line 292, in connect
    transport, proto = yield from self._create_connection(req)
  File "/usr/local/lib/python3.4/dist-packages/aiohttp/", line 588, in _create_connection
    (, req.port)) from exc
aiohttp.errors.ClientOSError: Can not connect to ::1:9001

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mx2323 commented Oct 8, 2015

looks like through a client with a session, it has to be specified via the connector, which is not intuitive or called out clearly in the documentation imo.


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asvetlov commented Oct 9, 2015

That makes sense, I see no objections for relaxing default family param from IPv4 to both IPv4 and IPv6.

@asvetlov asvetlov reopened this Oct 9, 2015

@asvetlov asvetlov added this to the 0.18 milestone Oct 9, 2015

@asvetlov asvetlov self-assigned this Oct 9, 2015

asvetlov added a commit that referenced this issue Oct 10, 2015

Merge pull request #561 from KeepSafe/family_zero
TCPConnector processes both IPv4 and IPv6 by default #559

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asvetlov commented Oct 10, 2015


@asvetlov asvetlov closed this Oct 10, 2015


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gwillem commented Oct 27, 2016

@asvetlov relaxing family breaks (cryptically) on systems with an IPv6 stack, aiodns installed but no IPv6 route. See saghul/aiodns#23

Not sure if pycares should default to IPv4 for gethostbyname. If not, then perhaps the aiohttp docs should include a warning about this situation.


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asvetlov commented Nov 1, 2016

aiodns is disabled by default by 9fbb7d7

@asvetlov asvetlov closed this Nov 1, 2016


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brunsgaard commented Nov 1, 2016

For other people wanting to use aiodns, but force IPv4, the solution is to make a custom connector, with family bound to socket.AF_INET (IPv4).

import aiohttp
import asyncio
import socket

async def main(loop):
    url = ''

    conn = aiohttp.TCPConnector(family=socket.AF_INET)
    async with aiohttp.ClientSession(connector=conn) as session:
        async with session.get(url) as resp:
            await resp.release()

loop = asyncio.get_event_loop()

I would just point that out, as I think it might be helpfull to some people out there ;)

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