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Date: Mon, 3 Aug 2020 11:15:54 +0300
From: Dmitry Samersoff <>
To:, Rich Felker <>
Subject: Re: getaddrinfo(3) with AI_V4MAPPED and AI_ALL flags

Hello Rich,

If you bind to ::ffff: on an IPv6 socket you will be able to 
receive IPv4 connection only.

If you bind to :: on an IPv6 socket you will be able to receive both,
IPv6 and IPv4 connections.

So, on my opinion, if ::ffff: is the only IPv4 address on the 
interface it should not be returned.


On 31.07.2020 22:19, Rich Felker wrote:
> On Fri, Jul 31, 2020 at 07:21:47PM +0300, Dmitry Samersoff wrote:
>> Hello Rich,
>> I'm not sure that mapping of INADDR_ANY ( and return of
>> ::ffff:' has any sense.
>> Should it be filtered out on musl level?
> This is an interesting question. What happens if you bind
> ::ffff: on an IPv6 socket? Is it the same as binding :: or does
> it produce a v6 socket that only accepts v4 connections? If it has its
> own distinct functionality then returning it when V4MAPPED is
> requested seems to make some sense.
> Rich

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