Can't UDP sendto named host

[richardkiss]

• uvloop v0.80:
• Python 3.6.1:
• Platform Mac OS X:
• Can you reproduce the bug with PYTHONASYNCIODEBUG in env? yes:

In uvloop 0.8.0, an error occurs when sending UDP data to a named host. The default asyncio eventloop allows it (and it probably shouldn't since sendto can block on the name lookup). Here is an example.

import uvloop


class P:
    def connection_made(self, transport):
        pass


async def go():
    loop = asyncio.get_event_loop()
    pair = await loop.create_datagram_endpoint(P, local_addr=("0.0.0.0", 6666))
    transport = pair[0]
    try:
        transport.sendto(b'foo', ("google.com", 6666))
    except Exception as ex:
        print(ex)

if 1:
    asyncio.set_event_loop_policy(uvloop.EventLoopPolicy())
asyncio.get_event_loop().run_until_complete(go())

[1st1]

Good catch. I've fixed uvloop to raise an error when a DNS lookup is needed in .sendto(). I will fix asyncio in a similar fashion. The fix will be in the next uvloop release in a couple of days.

[1st1]

Please try uvloop v0.9.0.