| msg298474 - (view) |
Author: Cecile Tonglet (cecton) |
Date: 2017-07-17 10:04 |
| The IPv6 detection in asyncio.base_events.create_server only detect if IPv6 is available instead of checking if the interface can actually support it. I noticed that by using Python in a Docker container (example code to reproduce in attachment): docker run -it --rm -v /tmp/test_ipv6.py:/src/test_ipv6.py python:3.6 python /src/test_ipv6.py Will result in: Traceback (most recent call last): File "/usr/local/lib/python3.6/asyncio/base_events.py", line 1043, in create_server sock.bind(sa) OSError: [Errno 99] Cannot assign requested address During handling of the above exception, another exception occurred: Traceback (most recent call last): File "/src/test_ipv6.py", line 11, in server = loop.run_until_complete(server_creation) File "/usr/local/lib/python3.6/asyncio/base_events.py", line 466, in run_until_complete return future.result() File "/usr/local/lib/python3.6/asyncio/base_events.py", line 1047, in create_server % (sa, err.strerror.lower())) OSError: [Errno 99] error while attempting to bind on address ('::1', 27015, 0, 0): cannot assign requested address By default Docker containers have only IPv4 enabled: 1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN group default qlen 1000 link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00 inet 127.0.0.1/8 scope host lo valid_lft forever preferred_lft forever 38: eth0@if39: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue state UP group default link/ether 02:42:ac:11:00:02 brd ff:ff:ff:ff:ff:ff inet 172.17.0.2/16 scope global eth0 valid_lft forever preferred_lft forever I believe this detection mechanism should rely on the interface requested. I found this on the web for Python 2 that manage to get the info per interface: https://pastebin.com/VEnhF1Ht but it's using an external library. However if you change the hostname to 127.0.0.1 it works normally. |
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| msg298683 - (view) |
Author: Antoine Pitrou (pitrou) *  |
Date: 2017-07-19 17:51 |
| Better than trying to detect IPv6 compatibility beforehand would probably to recognize the error and simply ignore it. Note: errno 99 is EADDRNOTAVAIL. Something like this could work (untested): diff --git a/Lib/asyncio/base_events.py b/Lib/asyncio/base_events.py index 33b8f48..413161a 100644 --- a/Lib/asyncio/base_events.py +++ b/Lib/asyncio/base_events.py @@ -1038,6 +1038,11 @@ class BaseEventLoop(events.AbstractEventLoop): try: sock.bind(sa) except OSError as err: + if err.errno == errno.EADDRNOTAVAIL: + # See bpo-30945 + sockets.pop() + sock.close() + continue raise OSError(err.errno, 'error while attempting ' 'to bind on address %r: %s' % (sa, err.strerror.lower())) from None |
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| msg298684 - (view) |
Author: Yury Selivanov (yselivanov) * |
Date: 2017-07-19 17:54 |
| > Better than trying to detect IPv6 compatibility beforehand would probably to recognize the error and simply ignore it. +1 |
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| msg298714 - (view) |
Author: Antoine Pitrou (pitrou) * |
Date: 2017-07-20 11:34 |
| Cécile, could you try the following patch? I have no easy way to test here. |
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| msg298716 - (view) |
Author: Cecile Tonglet (cecton) |
Date: 2017-07-20 11:57 |
| Sure! It seems to work, the process returns an exit code of 0 and I see no traceback but the message is still displayed in the terminal. (Also I did something weird because your patch applies on branch master and I ran it with Python 3.6... I suppose it shouldn't be a problem) [0] [11:54:13] /tmp > d run -it --rm -v /tmp:/tmp:ro -v ~/repos/cpython/Lib/asyncio:/usr/local/lib/python3.6/asyncio:ro python:3.6 python /tmp/test_ipv6.py error while attempting to bind on address ('::1', 27015, 0, 0): cannot assign requested address [0] [11:54:19] /tmp > d run -it --rm -v /tmp:/tmp:ro python:3.6 python /tmp/test_ipv6.py Traceback (most recent call last): File "/usr/local/lib/python3.6/asyncio/base_events.py", line 1043, in create_server sock.bind(sa) OSError: [Errno 99] Cannot assign requested address During handling of the above exception, another exception occurred: Traceback (most recent call last): File "/tmp/test_ipv6.py", line 11, in server = loop.run_until_complete(server_creation) File "/usr/local/lib/python3.6/asyncio/base_events.py", line 466, in run_until_complete return future.result() File "/usr/local/lib/python3.6/asyncio/base_events.py", line 1047, in create_server % (sa, err.strerror.lower())) OSError: [Errno 99] error while attempting to bind on address ('::1', 27015, 0, 0): cannot assign requested address [1] [11:54:52] /tmp > |
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| msg298718 - (view) |
Author: Antoine Pitrou (pitrou) * |
Date: 2017-07-20 12:46 |
| Cécile, thank you. The reason the message is still displayed is that I turned the error into a warning (in other words, it is expected). |
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| msg311915 - (view) |
Author: Anthony Sottile (Anthony Sottile) * |
Date: 2018-02-09 23:32 |
| Seeing this as well when running the cpython test suite in docker: ``` $ ./python -m test.test_asyncio ... [18 similar traces omitted] ====================================================================== ERROR: test_sock_sendfile_zero_size (test.test_asyncio.test_unix_events.SelectorEventLoopUnixSockSendfileTests) ---------------------------------------------------------------------- Traceback (most recent call last): File "/code/Lib/test/test_asyncio/test_unix_events.py", line 559, in test_sock_sendfile_zero_size sock, proto = self.prepare() File "/code/Lib/test/test_asyncio/test_unix_events.py", line 483, in prepare lambda: proto, support.HOST, port)) File "/code/Lib/test/test_asyncio/test_unix_events.py", line 476, in run_loop return self.loop.run_until_complete(coro) File "/code/Lib/asyncio/base_events.py", line 566, in run_until_complete return future.result() File "/code/Lib/asyncio/base_events.py", line 1346, in create_server % (sa, err.strerror.lower())) from None OSError: [Errno 99] error while attempting to bind on address ('::1', 39527, 0, 0): cannot assign requested address ---------------------------------------------------------------------- ``` I'm going to try and write a patch to skip these tests (there's already a helper) |
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| msg311916 - (view) |
Author: Anthony Sottile (Anthony Sottile) * |
Date: 2018-02-09 23:52 |
| Actually, my issue seems to be something more strange. The host being passed in is `localhost` which resolves to: ``` >>> pprint.pprint(socket.getaddrinfo('localhost', 80)) [(<AddressFamily.AF_INET: 2>, <SocketKind.SOCK_STREAM: 1>, 6, '', ('127.0.0.1', 80)), (<AddressFamily.AF_INET: 2>, <SocketKind.SOCK_DGRAM: 2>, 17, '', ('127.0.0.1', 80)), (<AddressFamily.AF_INET: 2>, <SocketKind.SOCK_RAW: 3>, 0, '', ('127.0.0.1', 80)), (<AddressFamily.AF_INET6: 10>, <SocketKind.SOCK_STREAM: 1>, 6, '', ('::1', 80, 0, 0)), (<AddressFamily.AF_INET6: 10>, <SocketKind.SOCK_DGRAM: 2>, 17, '', ('::1', 80, 0, 0)), (<AddressFamily.AF_INET6: 10>, <SocketKind.SOCK_RAW: 3>, 0, '', ('::1', 80, 0, 0))] ``` asyncio is picking ipv6 because of this code: https://github.com/python/cpython/blob/a445feb72902e4a3c5ae712f0c289309e1580d52/Lib/asyncio/base_events.py#L1334-L1340 despite my host not actually having an ipv6 network hooked up. |
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| msg311917 - (view) |
Author: Anthony Sottile (Anthony Sottile) * |
Date: 2018-02-09 23:53 |
| Applying this patch makes the tests pass for me, but I don't think the patch is appropriate (just hides the bug): ``` $ git diff diff --git a/Lib/test/test_asyncio/test_unix_events.py b/Lib/test/test_asyncio/test_unix_events.py index 5bd76d3..ff6c4e1 100644 --- a/Lib/test/test_asyncio/test_unix_events.py +++ b/Lib/test/test_asyncio/test_unix_events.py @@ -480,7 +480,7 @@ class SelectorEventLoopUnixSockSendfileTests(test_utils.TestCase): proto = self.MyProto(self.loop) port = support.find_unused_port() server = self.run_loop(self.loop.create_server( - lambda: proto, support.HOST, port)) + lambda: proto, support.HOSTv4, port)) self.run_loop(self.loop.sock_connect(sock, (support.HOST, port))) def cleanup(): ``` |
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| msg311942 - (view) |
Author: Cecile Tonglet (cecton) |
Date: 2018-02-10 07:25 |
| I see that the patch hasn't been applied to master on GitHub. Is there anything else expected from me on this ticket? |
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| msg317895 - (view) |
Author: Yury Selivanov (yselivanov) * |
Date: 2018-05-28 17:49 |
| Does anybody wants to make a PR to fix this? |
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| msg318045 - (view) |
Author: Yury Selivanov (yselivanov) * |
Date: 2018-05-29 15:29 |
| > asyncio is picking ipv6 because of this code: > https://github.com/python/cpython/blob/a445feb72902e4a3c5ae712f0c289309e1580d52/Lib/asyncio/base_events.py#L1334-L1340 > despite my host not actually having an ipv6 network hooked up. Which should be fine; create_server enumerates all addresses and tries to connect to each one. IPV6_V6ONLY is only applied to one socket for one IPv6 address. I think Antoine's patch is OK. |
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