From: Neng Chen <nchen@wavecomp.com>

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 <nchen@wavecomp.com>
Signed-off-by: Aleksandar Markovic <amarkovic@wavecomp.com>
---
 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);
+
+            ret = get_errno(setsockopt(sockfd, level, optname,
+                                       &ipv6mreq, sizeof(ipv6mreq)));
+            break;
+        }
         default:
             goto unimplemented;
         }
-- 
2.7.4

On 03/05/2019 19:50, Aleksandar Markovic wrote:
> From: Neng Chen <nchen@wavecomp.com>
> 
> 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 <nchen@wavecomp.com>
> Signed-off-by: Aleksandar Markovic <amarkovic@wavecomp.com>
> ---
>   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