From: Alexander Bluhm <bluhm@openbsd.org>
Subject: Re: have icmp6_reflect use route sourceaddr
To: David Gwynne <david@gwynne.id.au>
Cc: tech@openbsd.org
Date: Fri, 4 Jul 2025 09:10:28 +0200

On Thu, Jul 03, 2025 at 02:44:18PM +1000, David Gwynne wrote:
> this follows the pattern for source address selection in in6_src.c.
> this brings it into line with ipv4 and ipv6 pcb source address selection
> and ipv4 icmp_reflect source address selection.

Passes regress.  OK bluhm@

> Index: icmp6.c
> ===================================================================
> RCS file: /cvs/src/sys/netinet6/icmp6.c,v
> diff -u -p -r1.267 icmp6.c
> --- icmp6.c	12 Jun 2025 20:37:59 -0000	1.267
> +++ icmp6.c	3 Jul 2025 04:35:58 -0000
> @@ -1139,6 +1139,20 @@ icmp6_reflect(struct mbuf **mp, size_t o
>  			src = &ia6->ia_addr.sin6_addr;
>  		if (src == NULL)
>  			src = &ifatoia6(rt->rt_ifa)->ia_addr.sin6_addr;
> +
> +		/* route sourceaddr may override src address selection */
> +		if (ISSET(rt->rt_flags, RTF_GATEWAY)) {
> +			struct sockaddr *sourceaddr;
> +
> +			sourceaddr = rtable_getsource(rtableid, AF_INET6);
> +			if (sourceaddr != NULL) {
> +				struct ifaddr *ifa;
> +				ifa = ifa_ifwithaddr(sourceaddr, rtableid);
> +				if (ifa != NULL &&
> +				    ISSET(ifa->ifa_ifp->if_flags, IFF_UP))
> +					src = &satosin6(sourceaddr)->sin6_addr;
> +			}
> +		}
>  	}
>  
>  	ip6->ip6_src = *src;
> 
>