Add optional support for aiodns to TCPConnector for async DNS resolving

[asvetlov]

See http://stackoverflow.com/questions/34700311/how-to-handle-dns-timeouts-with-aiohttp for reasoning

[gwillem]

Thanks for your suggestions! To be solved:

1. The HTTP host header needs to be overwritten (easy)
2. SSL verification requires the true hostname. I have dug in the code but not found a way yet to cleanly pass the hostname to the SSL context (relevant code here)

[asvetlov]

TCPConnector._resolve https://github.com/KeepSafe/aiohttp/blob/master/aiohttp/connector.py#L531 performs DNS lookup if use_dns_cache for TCPConnector http://aiohttp.readthedocs.org/en/stable/client_reference.html#tcpconnector is True.
I suggest adding new ctor parameter use_aiodns (also False by default) to resolve through aiodns if use_dns_cache is True.

[fafhrd91]

-1 for use_aiodns, better is to invert dependency.
we need Resolver object, and pass that object as parameter to connector, then we can create default resolver that uses asyncio and aiodns one.

On Jan 10, 2016, at 4:26 AM, Andrew Svetlov notifications@github.com wrote:

TCPConnector._resolve https://github.com/KeepSafe/aiohttp/blob/master/aiohttp/connector.py#L531 https://github.com/KeepSafe/aiohttp/blob/master/aiohttp/connector.py#L531 performs DNS lookup if use_dns_cache for TCPConnector http://aiohttp.readthedocs.org/en/stable/client_reference.html#tcpconnector http://aiohttp.readthedocs.org/en/stable/client_reference.html#tcpconnector is True.
I suggest adding new ctor parameter use_aiodns (also False by default) to resolve through aiodns if use_dns_cache is True.

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Reply to this email directly or view it on GitHub #728 (comment).

[asvetlov]

Yes, Resolver sounds better than use_aiodns.
Thanks for correction.

[asvetlov]

Fixed by #819

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