On Sun, Mar 03, 2024 at 02:51:10PM +0100, Laurent Vivier wrote:
> in udp_update_hdr4():
> 
>     Assign the source address to src, either b->s_in.sin_addr,
>     c->ip4.dns_match or c->ip4.gw and then set b->iph.saddr to src->s_addr.
> 
> in udp_update_hdr6():
> 
>    Assign the source address to src, either b->s_in6.sin6_addr,
>    c->ip6.dns_match, c->ip6.gw or c->ip6.addr_ll.
>    Assign the destination to dst, either c->ip6.addr_seen or
>    &c->ip6.addr_ll_seen.
>    Then set dst to b->ip6h.daddr and src to b->ip6h.saddr.
> 
> Signed-off-by: Laurent Vivier <lvivier@redhat.com>

Heh, this does something quite similar to one of the patches in my
small udp cleanups series.

Reviewed-by: David Gibson <david@gibson.dropbear.id.au>

I don't want to delay this further, so I'll rebase my other UDP work
on top of this.


> ---
> 
> Notes:
>     v5:
>       - new patch to introduce the use of struct in_addr with
>         csum_ip4_header()
> 
>  udp.c | 39 +++++++++++++++++++--------------------
>  1 file changed, 19 insertions(+), 20 deletions(-)
> 
> diff --git a/udp.c b/udp.c
> index 26774df7018c..2b41a1bdff61 100644
> --- a/udp.c
> +++ b/udp.c
> @@ -588,7 +588,7 @@ static size_t udp_update_hdr4(const struct ctx *c, int n, in_port_t dstport,
>  			      const struct timespec *now)
>  {
>  	struct udp4_l2_buf_t *b = &udp4_l2_buf[n];
> -	struct in_addr *src;
> +	const struct in_addr *src;
>  	in_port_t src_port;
>  	size_t ip_len;
>  
> @@ -602,10 +602,9 @@ static size_t udp_update_hdr4(const struct ctx *c, int n, in_port_t dstport,
>  
>  	if (!IN4_IS_ADDR_UNSPECIFIED(&c->ip4.dns_match) &&
>  	    IN4_ARE_ADDR_EQUAL(src, &c->ip4.dns_host) && src_port == 53) {
> -		b->iph.saddr = c->ip4.dns_match.s_addr;
> +		src = &c->ip4.dns_match;
>  	} else if (IN4_IS_ADDR_LOOPBACK(src) ||
>  		   IN4_ARE_ADDR_EQUAL(src, &c->ip4.addr_seen)) {
> -		b->iph.saddr = c->ip4.gw.s_addr;
>  		udp_tap_map[V4][src_port].ts = now->tv_sec;
>  		udp_tap_map[V4][src_port].flags |= PORT_LOCAL;
>  
> @@ -615,9 +614,10 @@ static size_t udp_update_hdr4(const struct ctx *c, int n, in_port_t dstport,
>  			udp_tap_map[V4][src_port].flags &= ~PORT_LOOPBACK;
>  
>  		bitmap_set(udp_act[V4][UDP_ACT_TAP], src_port);
> -	} else {
> -		b->iph.saddr = src->s_addr;
> +
> +		src = &c->ip4.gw;
>  	}
> +	b->iph.saddr = src->s_addr;
>  
>  	udp_update_check4(b);
>  	b->uh.source = b->s_in.sin_port;
> @@ -640,10 +640,11 @@ static size_t udp_update_hdr6(const struct ctx *c, int n, in_port_t dstport,
>  			      const struct timespec *now)
>  {
>  	struct udp6_l2_buf_t *b = &udp6_l2_buf[n];
> -	struct in6_addr *src;
> +	const struct in6_addr *src, *dst;
>  	in_port_t src_port;
>  	size_t ip_len;
>  
> +	dst = &c->ip6.addr_seen;
>  	src = &b->s_in6.sin6_addr;
>  	src_port = ntohs(b->s_in6.sin6_port);
>  
> @@ -652,23 +653,14 @@ static size_t udp_update_hdr6(const struct ctx *c, int n, in_port_t dstport,
>  	b->ip6h.payload_len = htons(udp6_l2_mh_sock[n].msg_len + sizeof(b->uh));
>  
>  	if (IN6_IS_ADDR_LINKLOCAL(src)) {
> -		b->ip6h.daddr = c->ip6.addr_ll_seen;
> -		b->ip6h.saddr = b->s_in6.sin6_addr;
> +		dst = &c->ip6.addr_ll_seen;
>  	} else if (!IN6_IS_ADDR_UNSPECIFIED(&c->ip6.dns_match) &&
>  		   IN6_ARE_ADDR_EQUAL(src, &c->ip6.dns_host) &&
>  		   src_port == 53) {
> -		b->ip6h.daddr = c->ip6.addr_seen;
> -		b->ip6h.saddr = c->ip6.dns_match;
> +		src = &c->ip6.dns_match;
>  	} else if (IN6_IS_ADDR_LOOPBACK(src)			||
>  		   IN6_ARE_ADDR_EQUAL(src, &c->ip6.addr_seen)	||
>  		   IN6_ARE_ADDR_EQUAL(src, &c->ip6.addr)) {
> -		b->ip6h.daddr = c->ip6.addr_ll_seen;
> -
> -		if (IN6_IS_ADDR_LINKLOCAL(&c->ip6.gw))
> -			b->ip6h.saddr = c->ip6.gw;
> -		else
> -			b->ip6h.saddr = c->ip6.addr_ll;
> -
>  		udp_tap_map[V6][src_port].ts = now->tv_sec;
>  		udp_tap_map[V6][src_port].flags |= PORT_LOCAL;
>  
> @@ -683,10 +675,17 @@ static size_t udp_update_hdr6(const struct ctx *c, int n, in_port_t dstport,
>  			udp_tap_map[V6][src_port].flags &= ~PORT_GUA;
>  
>  		bitmap_set(udp_act[V6][UDP_ACT_TAP], src_port);
> -	} else {
> -		b->ip6h.daddr = c->ip6.addr_seen;
> -		b->ip6h.saddr = b->s_in6.sin6_addr;
> +
> +		dst = &c->ip6.addr_ll_seen;
> +
> +		if (IN6_IS_ADDR_LINKLOCAL(&c->ip6.gw))
> +			src = &c->ip6.gw;
> +		else
> +			src = &c->ip6.addr_ll;
> +
>  	}
> +	b->ip6h.daddr = *dst;
> +	b->ip6h.saddr = *src;
>  
>  	b->uh.source = b->s_in6.sin6_port;
>  	b->uh.dest = htons(dstport);

-- 
David Gibson			| I'll have my music baroque, and my code
david AT gibson.dropbear.id.au	| minimalist, thank you.  NOT _the_ _other_
				| _way_ _around_!
http://www.ozlabs.org/~dgibson