Re: [Qemu-devel] [PATCH v4 4/5] linux-user: Add support for setsockopt() options IPV6_<ADD|DROP>_MEMBERSHIP

[Laurent Vivier]

On 03/05/2019 19:50, Aleksandar Markovic wrote:
> From: Neng Chen <address@hidden>
>
> Add support for options IPV6_ADD_MEMBERSHIP and IPV6_DROP_MEMPEMBERSHIP
> of the syscall setsockopt(). These options control membership in
> multicast groups. Their argument is a pointer to a struct ipv6_mreq,
> which is in turn defined as:
>
> struct ipv6_mreq {
>      /* IPv6 multicast address of group */
>      struct in6_addr  ipv6mr_multiaddr;
>      /* local IPv6 address of interface */
>      int              ipv6mr_interface;
> };
>
> The in6_addr structure consists of fields that are always big-endian
> (on host of any endian), so the ipv6_mreq's field ipv6mr_multiaddr
> doesn't need any endian conversion, whereas ipv6mr_interface does.
>
> Signed-off-by: Neng Chen <address@hidden>
> Signed-off-by: Aleksandar Markovic <address@hidden>
> ---
>   linux-user/syscall.c | 19 +++++++++++++++++++
>   1 file changed, 19 insertions(+)
>
> diff --git a/linux-user/syscall.c b/linux-user/syscall.c
> index 96cd4bf..b7eb4b7 100644
> --- a/linux-user/syscall.c
> +++ b/linux-user/syscall.c
> @@ -1892,6 +1892,25 @@ static abi_long do_setsockopt(int sockfd, int level, int 
> optname,
>                                          &pki, sizeof(pki)));
>               break;
>           }
> +        case IPV6_ADD_MEMBERSHIP:
> +        case IPV6_DROP_MEMBERSHIP:
> +        {
> +            struct ipv6_mreq ipv6mreq;
> +
> +            if (optlen < sizeof(ipv6mreq)) {
> +                return -TARGET_EINVAL;
> +            }
> +
> +            if (copy_from_user(&ipv6mreq, optval_addr, sizeof(ipv6mreq))) {
> +                return -TARGET_EFAULT;
> +            }
> +
> +            ipv6mreq.ipv6mr_interface = tswap32(ipv6mreq.ipv6mr_interface);

The name of this field seems to depend on where it is defined: in 
netinet/in.h, it's ipv6mr_interface, but in linux/in6.h it's 
ipv6mr_ifindex. I think you should check "__UAPI_DEF_IPV6_MREQ" to use 
the good one.

> +
> +            ret = get_errno(setsockopt(sockfd, level, optname,
> +                                       &ipv6mreq, sizeof(ipv6mreq)));
> +            break;
> +        }
>           default:
>               goto unimplemented;
>           }

Thanks,
Laurent