ws2_32: Filter unset bits when argument is smaller than 32 bits.

dlls/ws2_32/socket.c

@@ -5013,6 +5013,7 @@ int WINAPI WS_setsockopt(SOCKET s, int level, int optname,
     {
         woptval= *((const INT16 *) optval);
         optval= (char*) &woptval;
+        woptval&= (1 << optlen * 8) - 1;
         optlen=sizeof(int);
     }
     fd = get_sock_fd( s, 0, NULL );

dlls/ws2_32/tests/sock.c

@@ -1374,6 +1374,23 @@ todo_wine
 
     closesocket(s);
 
+    /* Test WS_IP_MULTICAST_TTL with 8, 16, 24 and 32 bits values */
+    s = socket(AF_INET, SOCK_DGRAM, 0);
+    ok(s != INVALID_SOCKET, "Failed to create socket\n");
+    size = sizeof(i);
+    for (i = 0; i < 4; i++)
+    {
+        int k, j;
+        const int tests[] = {0xffffff0a, 0xffff000b, 0xff00000c, 0x0000000d};
+        err = setsockopt(s, IPPROTO_IP, IP_MULTICAST_TTL, (char *) &tests[i], i + 1);
+        ok(!err, "Test [%d] Expected 0, got %d\n", i, err);
+        err = getsockopt(s, IPPROTO_IP, IP_MULTICAST_TTL, (char *) &k, &size);
+        ok(!err, "Test [%d] Expected 0, got %d\n", i, err);
+        j = i != 3 ? tests[i] & ((1 << (i + 1) * 8) - 1) : tests[i];
+        ok(k == j, "Test [%d] Expected 0x%x, got 0x%x\n", i, j, k);
+    }
+    closesocket(s);
+
     /* test SO_PROTOCOL_INFOA invalid parameters */
     ok(getsockopt(INVALID_SOCKET, SOL_SOCKET, SO_PROTOCOL_INFOA, NULL, NULL),
        "getsockopt should have failed\n");