From: Helge Deller <deller@gmx.de>

Share code with IP_ADD_MEMBERSHIP/IP_DROP_MEMBERSHIP.

Signed-off-by: Helge Deller <deller@gmx.de>
---
 linux-user/syscall.c | 13 +++++++++++--
 1 file changed, 11 insertions(+), 2 deletions(-)

diff --git a/linux-user/syscall.c b/linux-user/syscall.c
index bbe2560927..4360543e20 100644
--- a/linux-user/syscall.c
+++ b/linux-user/syscall.c
@@ -2130,16 +2130,23 @@ static abi_long do_setsockopt(int sockfd, int level, int optname,
             }
             ret = get_errno(setsockopt(sockfd, level, optname, &val, sizeof(val)));
             break;
+        case IP_MULTICAST_IF:
         case IP_ADD_MEMBERSHIP:
         case IP_DROP_MEMBERSHIP:
         {
             struct ip_mreqn ip_mreq;
             struct target_ip_mreqn *target_smreqn;
+            int min_size;
 
             QEMU_BUILD_BUG_ON(sizeof(struct ip_mreq) !=
                               sizeof(struct target_ip_mreq));
 
-            if (optlen < sizeof (struct target_ip_mreq) ||
+            if (optname == IP_MULTICAST_IF) {
+                min_size = sizeof(struct in_addr);
+            } else {
+                min_size = sizeof(struct target_ip_mreq);
+            }
+            if (optlen < min_size ||
                 optlen > sizeof (struct target_ip_mreqn)) {
                 return -TARGET_EINVAL;
             }
@@ -2149,7 +2156,9 @@ static abi_long do_setsockopt(int sockfd, int level, int optname,
                 return -TARGET_EFAULT;
             }
             ip_mreq.imr_multiaddr.s_addr = target_smreqn->imr_multiaddr.s_addr;
-            ip_mreq.imr_address.s_addr = target_smreqn->imr_address.s_addr;
+            if (optlen >= sizeof(struct target_ip_mreq)) {
+                ip_mreq.imr_address.s_addr = target_smreqn->imr_address.s_addr;
+            }
             if (optlen == sizeof(struct target_ip_mreqn)) {
                 ip_mreq.imr_ifindex = tswapal(target_smreqn->imr_ifindex);
                 optlen = sizeof(struct ip_mreqn);
-- 
2.47.0