wireguard android don't prefer IPV6 endpoint

[Harsh Shandilya]

Hey Jérémy,

On 2021-01-03 15:58, Jérémy Prego wrote:
> hello Harsh,
> 
>> The WireGuard Android client is designed to prefer IPv4 over IPv6 as
>> of now
> why did you make this choice? is there a known bug with ipv6? I think 
> it
> would be useful to put an option in the wireguard application, so that
> we can choose.

Seems like the origin of this behavior is this[1] commit that cites 
issues with DNS64. I've CC'ed Jason who originally wrote the commit and 
should have better insight into it.

> 
> if I want to use an ipv6 tunnel, do I have another solution than to
> create 2 tunels, one in ipv6 only, and another in ipv4 in order to be
> able to use ipv6 when available and ipv4 when the place where i am has
> no ipv6?

I believe that's the way as of now, yes.

> 
> I did not manage to add 2 endpoint in a single tunnel to put an 
> endpoint
> only ipv6 and another endpoint ipv4 / ipv6 to bypass the problem
> 
> thanks,
> 
> Jerem
> Le 03/01/2021 à 14:48, Harsh Shandilya a écrit :
>> Hey Jérémy,
>> 
>> On 2021-01-02 08:27, Jérémy Prego wrote:
>>> I confirm the same problem in wifi
>>> 
>>> Le 27/12/2020 à 07:02, Jérémy Prego a écrit :
>>>> hello,
>>>> 
>>>> I've always encountered a bug with android wireguard when using an 
>>>> ipv4
>>>> / ipv6 endpoint.
>>>> 
>>>> I tested with two phones:
>>>> Huawei p10 lite android 8.0 emui 8
>>>> Xiaomi poco m3 android 10.0 miui 12
>>>> 
>>>> When i'm in LTE (not yet been able to test in wifi), wireguard 
>>>> connects
>>>> to the endpoint in ipv4 and not in ipv6, and i don't understand why 
>>>> it
>>>> is doing that.
>> 
>> The WireGuard Android client is designed to prefer IPv4 over IPv6 as
>> of now
>> (https://git.zx2c4.com/wireguard-android/tree/tunnel/src/main/java/com/wireguard/config/InetEndpoint.java#n97).
>> This may or may not change in the future, and we'll announce here if
>> it does.
>> 
>>>> However, chrome, for example, does use ipv6 by default and not ipv4.
>>>> 
>>>> My phone does recover an ipv6 in 2a01: cb1a ........ / 64 and not an
>>>> ipv6 type fc00 / fd00 / fe80 ...
>>>> I also specify that if I only have an AAAA record, the tunnel works
>>>> fine
>>>> in ipv6. but suddenly, I can no longer connect to wifi which only
>>>> have ipv4.
>>>> 
>>>> I would like wireguard to favor ipv6 when it is available, and
>>>> otherwise
>>>> switch to ipv4.
>>>> 
>>>> Is it possible ?
>>>> 
>>>> Thanks,
>>>> 
>>>> Jerem
>> 
>> Cheers,
>> Harsh

1: 
https://git.zx2c4.com/wireguard-android/commit/?h=c23d58bc27cf9807fc3405c8c99cc67cf4b21f25

Cheers,
Harsh