[Qemu-devel] [PATCH v6 4/6] linux-user: Add support for setsockopt() options IPV6_<ADD|DROP>_MEMBERSHIP

[Aleksandar Markovic <aleksandar.markovic@rt-rk.com>]

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 in IP v6 header netinet/in.h as:

 struct ipv6_mreq {
     /* IPv6 multicast address of group */
     struct  in6_addr  ipv6mr_multiaddr;
     /* local IPv6 address of interface */
     int     ipv6mr_interface;
 };

...whereas its definition in kernel's include/uapi/linux/in6.h is:

 #if __UAPI_DEF_IPV6_MREQ
 struct ipv6_mreq {
     /* IPv6 multicast address of group */
         struct  in6_addr ipv6mr_multiaddr;
     /* local IPv6 address of interface */
     int     ipv6mr_ifindex;
 };
 #endif

The first field of ipv6_mreq has the same name ("ipv6mr_multiaddr")
and type ("in6_addr") in both cases. Moreover, the in6_addr structure
consists of fields that are always big-endian (on host of any endian),
therefore the ipv6_mreq's field ipv6mr_multiaddr doesn't need any
endian conversion.

The second field of ipv6_mreq may, however, depending on the build
environment, have different names. This is the reason why the line
"#if __UAPI_DEF_IPV6_MREQ" is used in this patch - to establish the
right choice for the field name. Also, endian conversion is needed
for this field, since it is of type "int".

Signed-off-by: Neng Chen <nchen@wavecomp.com>
Signed-off-by: Aleksandar Markovic <amarkovic@wavecomp.com>
---
 linux-user/syscall.c | 23 +++++++++++++++++++++++
 1 file changed, 23 insertions(+)

diff --git a/linux-user/syscall.c b/linux-user/syscall.c
index 96cd4bf..acff14d 100644
--- a/linux-user/syscall.c
+++ b/linux-user/syscall.c
@@ -1892,6 +1892,29 @@ 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;
+            }
+
+#if __UAPI_DEF_IPV6_MREQ
+            ipv6mreq.ipv6mr_ifindex = tswap32(ipv6mreq.ipv6mr_ifindex);
+#else
+            ipv6mreq.ipv6mr_interface = tswap32(ipv6mreq.ipv6mr_interface);
+#endif /* __UAPI_DEF_IVP6_MREQ */
+
+            ret = get_errno(setsockopt(sockfd, level, optname,
+                                       &ipv6mreq, sizeof(ipv6mreq)));
+            break;
+        }
         default:
             goto unimplemented;
         }
-- 
2.7.4