netdev - Re: [[PATCH net-next v3] 3/3] udp6: Use Segment Routing Header for dest address if present

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Message-ID: <b77ecea5-0a46-a867-8df5-21fa8ffe6354@gmail.com>
Date:   Fri, 3 Dec 2021 09:51:01 -0700
From:   David Ahern <dsahern@...il.com>
To:     Andrew Lunn <andrew@...n.ch>, David Miller <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>
Cc:     Hideaki YOSHIFUJI <yoshfuji@...ux-ipv6.org>,
        David Ahern <dsahern@...nel.org>,
        Willem de Bruijn <willemb@...gle.com>,
        James Prestwood <prestwoj@...il.com>,
        Justin Iurman <justin.iurman@...ege.be>,
        Praveen Chaudhary <praveen5582@...il.com>,
        "Jason A . Donenfeld" <Jason@...c4.com>,
        Eric Dumazet <edumazet@...gle.com>,
        netdev <netdev@...r.kernel.org>
Subject: Re: [[PATCH net-next v3] 3/3] udp6: Use Segment Routing Header for
 dest address if present

On 12/3/21 9:29 AM, Andrew Lunn wrote:
> diff --git a/net/ipv6/seg6.c b/net/ipv6/seg6.c
> index 73aaabf0e966..4fd7d3793c1b 100644
> --- a/net/ipv6/seg6.c
> +++ b/net/ipv6/seg6.c
> @@ -134,6 +134,27 @@ void seg6_icmp_srh(struct sk_buff *skb, struct inet6_skb_parm *opt)
>  	skb->network_header = network_header;
>  }
>  
> +/* If the packet which invoked an ICMP error contains an SRH return
> + * the true destination address from within the SRH, otherwise use the
> + * destination address in the IP header.
> + */
> +const struct in6_addr *seg6_get_daddr(struct sk_buff *skb,
> +				      struct inet6_skb_parm *opt)
> +{
> +	/* ipv6_hdr() does not work here, since this IP header is
> +	 * nested inside an ICMP error report packet
> +	 */
> +	const struct ipv6hdr *hdr = (const struct ipv6hdr *)skb->data;
> +	struct ipv6_sr_hdr *srh;
> +
> +	if (opt->flags & IP6SKB_SEG6) {
> +		srh = (struct ipv6_sr_hdr *)(skb->data + opt->srhoff);
> +		return  &srh->segments[0];
> +	}
> +
> +	return &hdr->daddr;
> +}
> +

also, that could be an inline in net/seg6.h given how short it is.