Re: [Qemu-devel] [PATCH 5/5] slirp: Add RDNSS advertisement

[Thomas Huth <thuth@redhat.com>]

On 29.03.2016 01:44, Samuel Thibault wrote:
> This adds the RDNSS option to IPv6 router advertisements, so that the guest
> can autoconfigure the DNS server address.
> 
> Signed-off-by: Samuel Thibault <samuel.thibault@ens-lyon.org>
> ---
>  slirp/ip6_icmp.c | 19 ++++++++++++++++---
>  slirp/ip6_icmp.h | 12 ++++++++++--
>  2 files changed, 26 insertions(+), 5 deletions(-)
> 
> diff --git a/slirp/ip6_icmp.c b/slirp/ip6_icmp.c
> index 09571bc..74585d1 100644
> --- a/slirp/ip6_icmp.c
> +++ b/slirp/ip6_icmp.c
> @@ -149,7 +149,8 @@ void ndp_send_ra(Slirp *slirp)
>      rip->ip_nh = IPPROTO_ICMPV6;
>      rip->ip_pl = htons(ICMP6_NDP_RA_MINLEN
>                          + NDPOPT_LINKLAYER_LEN
> -                        + NDPOPT_PREFIXINFO_LEN);
> +                        + NDPOPT_PREFIXINFO_LEN
> +                        + NDPOPT_RDNSS_LEN);
>      t->m_len = sizeof(struct ip6) + ntohs(rip->ip_pl);
>  
>      /* Build ICMPv6 packet */
> @@ -167,16 +168,16 @@ void ndp_send_ra(Slirp *slirp)
>      ricmp->icmp6_nra.lifetime = htons(NDP_AdvDefaultLifetime);
>      ricmp->icmp6_nra.reach_time = htonl(NDP_AdvReachableTime);
>      ricmp->icmp6_nra.retrans_time = htonl(NDP_AdvRetransTime);
> +    t->m_data += ICMP6_NDP_RA_MINLEN;
>  
>      /* Source link-layer address (NDP option) */
> -    t->m_data += ICMP6_NDP_RA_MINLEN;
>      struct ndpopt *opt = mtod(t, struct ndpopt *);
>      opt->ndpopt_type = NDPOPT_LINKLAYER_SOURCE;
>      opt->ndpopt_len = NDPOPT_LINKLAYER_LEN / 8;
>      in6_compute_ethaddr(rip->ip_src, opt->ndpopt_linklayer);
> +    t->m_data += NDPOPT_LINKLAYER_LEN;
>  
>      /* Prefix information (NDP option) */
> -    t->m_data += NDPOPT_LINKLAYER_LEN;
>      struct ndpopt *opt2 = mtod(t, struct ndpopt *);
>      opt2->ndpopt_type = NDPOPT_PREFIX_INFO;
>      opt2->ndpopt_len = NDPOPT_PREFIXINFO_LEN / 8;
> @@ -188,8 +189,20 @@ void ndp_send_ra(Slirp *slirp)
>      opt2->ndpopt_prefixinfo.pref_lt = htonl(NDP_AdvPrefLifetime);
>      opt2->ndpopt_prefixinfo.reserved2 = 0;
>      opt2->ndpopt_prefixinfo.prefix = slirp->vprefix_addr6;
> +    t->m_data += NDPOPT_PREFIXINFO_LEN;
> +
> +    /* Prefix information (NDP option) */
> +    struct ndpopt *opt3 = mtod(t, struct ndpopt *);
> +    opt3->ndpopt_type = NDPOPT_RDNSS;
> +    opt3->ndpopt_len = NDPOPT_RDNSS_LEN / 8;
> +    opt3->ndpopt_rdnss.reserved = 0;
> +    opt3->ndpopt_rdnss.lifetime = htonl(2 * NDP_MaxRtrAdvInterval);
> +    opt3->ndpopt_rdnss.addr = slirp->vnameserver_addr6;
> +    t->m_data += NDPOPT_RDNSS_LEN;
>  
>      /* ICMPv6 Checksum */
> +    t->m_data -= NDPOPT_RDNSS_LEN;
> +    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);
> diff --git a/slirp/ip6_icmp.h b/slirp/ip6_icmp.h
> index 9460bf8..2282d29 100644
> --- a/slirp/ip6_icmp.h
> +++ b/slirp/ip6_icmp.h
> @@ -122,6 +122,7 @@ struct ndpopt {
>      uint8_t     ndpopt_len;                     /* /!\ In units of 8 octets */
>      union {
>          unsigned char   linklayer_addr[6];      /* Source/Target Link-layer */
> +#define ndpopt_linklayer ndpopt_body.linklayer_addr
>          struct prefixinfo {                     /* Prefix Information */
>              uint8_t     prefix_length;
>  #ifdef HOST_WORDS_BIGENDIAN
> @@ -134,19 +135,26 @@ struct ndpopt {
>              uint32_t    reserved2;
>              struct in6_addr prefix;
>          } QEMU_PACKED prefixinfo;
> -    } ndpopt_body;
> -#define ndpopt_linklayer ndpopt_body.linklayer_addr
>  #define ndpopt_prefixinfo ndpopt_body.prefixinfo
> +        struct rdnss {
> +            uint16_t reserved;
> +            uint32_t lifetime;
> +            struct in6_addr addr;
> +        } QEMU_PACKED rdnss;
> +#define ndpopt_rdnss ndpopt_body.rdnss
> +    } ndpopt_body;
>  } QEMU_PACKED;
>  
>  /* NDP options type */
>  #define NDPOPT_LINKLAYER_SOURCE     1   /* Source Link-Layer Address */
>  #define NDPOPT_LINKLAYER_TARGET     2   /* Target Link-Layer Address */
>  #define NDPOPT_PREFIX_INFO          3   /* Prefix Information */
> +#define NDPOPT_RDNSS                25  /* Recursive DNS Server Address */
>  
>  /* NDP options size, in octets. */
>  #define NDPOPT_LINKLAYER_LEN    8
>  #define NDPOPT_PREFIXINFO_LEN   32
> +#define NDPOPT_RDNSS_LEN        24
>  
>  /*
>   * Definition of type and code field values.
> 

Reviewed-by: Thomas Huth <thuth@redhat.com>