Re: [Qemu-devel] [PATCH 1/2] slirp: Make RA build more flexible

[Philippe Mathieu-Daudé]

On 03/26/2017 03:46 PM, Samuel Thibault wrote:
> Do not hardcode the RA size at all, use a pl_size variable which
> accounts the accumulated size, and fill rip->ip_pl at the end.
>
> This will allow to make some blocks optional.
>
> Signed-off-by: Samuel Thibault <address@hidden>

Reviewed-by: Philippe Mathieu-Daudé <address@hidden>

> ---
>  slirp/ip6_icmp.c | 24 +++++++++---------------
>  1 file changed, 9 insertions(+), 15 deletions(-)
>
> diff --git a/slirp/ip6_icmp.c b/slirp/ip6_icmp.c
> index 298a48dd25..d0f5cc1456 100644
> --- a/slirp/ip6_icmp.c
> +++ b/slirp/ip6_icmp.c
> @@ -143,17 +143,10 @@ void ndp_send_ra(Slirp *slirp)
>      /* Build IPv6 packet */
>      struct mbuf *t = m_get(slirp);
>      struct ip6 *rip = mtod(t, struct ip6 *);
> +    size_t pl_size = 0;
>      rip->ip_src = (struct in6_addr)LINKLOCAL_ADDR;
>      rip->ip_dst = (struct in6_addr)ALLNODES_MULTICAST;
>      rip->ip_nh = IPPROTO_ICMPV6;
> -    rip->ip_pl = htons(ICMP6_NDP_RA_MINLEN
> -                        + NDPOPT_LINKLAYER_LEN
> -                        + NDPOPT_PREFIXINFO_LEN
> -#ifndef _WIN32
> -                        + NDPOPT_RDNSS_LEN
> -#endif
> -                        );
> -    t->m_len = sizeof(struct ip6) + ntohs(rip->ip_pl);
>
>      /* Build ICMPv6 packet */
>      t->m_data += sizeof(struct ip6);
> @@ -171,6 +164,7 @@ void ndp_send_ra(Slirp *slirp)
>      ricmp->icmp6_nra.reach_time = htonl(NDP_AdvReachableTime);
>      ricmp->icmp6_nra.retrans_time = htonl(NDP_AdvRetransTime);
>      t->m_data += ICMP6_NDP_RA_MINLEN;
> +    pl_size += ICMP6_NDP_RA_MINLEN;
>
>      /* Source link-layer address (NDP option) */
>      struct ndpopt *opt = mtod(t, struct ndpopt *);
> @@ -178,6 +172,7 @@ void ndp_send_ra(Slirp *slirp)
>      opt->ndpopt_len = NDPOPT_LINKLAYER_LEN / 8;
>      in6_compute_ethaddr(rip->ip_src, opt->ndpopt_linklayer);
>      t->m_data += NDPOPT_LINKLAYER_LEN;
> +    pl_size += NDPOPT_LINKLAYER_LEN;
>
>      /* Prefix information (NDP option) */
>      struct ndpopt *opt2 = mtod(t, struct ndpopt *);
> @@ -192,6 +187,7 @@ void ndp_send_ra(Slirp *slirp)
>      opt2->ndpopt_prefixinfo.reserved2 = 0;
>      opt2->ndpopt_prefixinfo.prefix = slirp->vprefix_addr6;
>      t->m_data += NDPOPT_PREFIXINFO_LEN;
> +    pl_size += NDPOPT_PREFIXINFO_LEN;
>
>  #ifndef _WIN32
>      /* Prefix information (NDP option) */
> @@ -203,16 +199,14 @@ void ndp_send_ra(Slirp *slirp)
>      opt3->ndpopt_rdnss.lifetime = htonl(2 * NDP_MaxRtrAdvInterval);
>      opt3->ndpopt_rdnss.addr = slirp->vnameserver_addr6;
>      t->m_data += NDPOPT_RDNSS_LEN;
> +    pl_size += NDPOPT_RDNSS_LEN;
>  #endif
>
> +    rip->ip_pl = htons(pl_size);
> +    t->m_data -= sizeof(struct ip6) + pl_size;
> +    t->m_len = sizeof(struct ip6) + pl_size;
> +
>      /* ICMPv6 Checksum */
> -#ifndef _WIN32
> -    t->m_data -= NDPOPT_RDNSS_LEN;
> -#endif
> -    t->m_data -= NDPOPT_PREFIXINFO_LEN;
> -    t->m_data -= NDPOPT_LINKLAYER_LEN;
> -    t->m_data -= ICMP6_NDP_RA_MINLEN;
> -    t->m_data -= sizeof(struct ip6);
>      ricmp->icmp6_cksum = ip6_cksum(t);
>
>      ip6_output(NULL, t, 0);