EADDRNOTAVAIL in sendto(3p)

EADDRNOTAVAIL in sendto(3p)

[Angel Ruiz Fernandez]

Hello,

I think there is a missing error in the ERRORS section of sendto(3p)

When doing a sendto() to a Link-local scope IPv6 address on a socket 
that is bound to in6addr_any which has not been set 
setsockopt(IPV6_MULTICAST_IF) to a valid interface value, it fails with 
EADDRNOTAVAIL because it does not know which interface to send the 
multicast packet from.

I can make a patch later.

Regards,
Angel

Re: EADDRNOTAVAIL in sendto(3p)

[Alejandro Colomar]

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On Tue, Jan 06, 2026 at 04:44:18PM +0100, Angel Ruiz Fernandez wrote:
> Hello,

Hi Angel,

> I think there is a missing error in the ERRORS section of sendto(3p)
> 
> When doing a sendto() to a Link-local scope IPv6 address on a socket that is
> bound to in6addr_any which has not been set setsockopt(IPV6_MULTICAST_IF) to
> a valid interface value, it fails with EADDRNOTAVAIL because it does not
> know which interface to send the multicast packet from.

Possibly.

> I can make a patch later.

Thanks!  It would be good to include (in the commit message) a small
C program demonstrating this.  And also include links to kernel source
if possible, or CC anyone who could confirm.  The more help it includes,
the easier it will be to review.


Have a lovely day!
Alex

> 
> Regards,
> Angel
> 

-- 
<https://www.alejandro-colomar.es>

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