public static extern int ioctl(int fd, AixIoctlRequest request, ref AixStructs.ifreq_addrin arg);
public override IPAddress GetNetMask(IPAddress address)
{
AixStructs.ifconf ifc;
ifc.ifc_len = 0;
ifc.ifc_buf = IntPtr.Zero;
int sockfd = -1;
try {
sockfd = socket(AixAddressFamily.AF_INET, SOCK_DGRAM, 0);
if (sockfd == -1)
{
throw new SystemException("socket for SIOCGIFCONF failed");
}
if (ioctl(sockfd, AixIoctlRequest.SIOCGSIZIFCONF, ref ifc.ifc_len) < 0 || ifc.ifc_len < 1)
{
throw new SystemException("ioctl for SIOCGSIZIFCONF failed");
}
ifc.ifc_buf = Marshal.AllocHGlobal(ifc.ifc_len);
if (ioctl(sockfd, AixIoctlRequest.SIOCGIFCONF, ref ifc) < 0)
{
throw new SystemException("ioctl for SIOCGIFCONF failed");
}
// this is required because the buffer is an array of VARIABLE LENGTH structures, so sane marshalling is impossible
AixStructs.ifreq ifr;
var curPos = ifc.ifc_buf;
var endPos = ifc.ifc_buf.ToInt64() + ifc.ifc_len;
for (ifr = (AixStructs.ifreq)Marshal.PtrToStructure(curPos, typeof(AixStructs.ifreq));
curPos.ToInt64() < endPos;
// name length + sockaddr length (SIOCGIFCONF only deals in those)
curPos += (16 + ifr.ifru_addr.sa_len))
{
// update the structure for next increment
ifr = (AixStructs.ifreq)Marshal.PtrToStructure(curPos, typeof(AixStructs.ifreq));
if (Enum.IsDefined(typeof(AixAddressFamily), (int)ifr.ifru_addr.sa_family))
{
switch ((AixAddressFamily)ifr.ifru_addr.sa_family)
{
case AixAddressFamily.AF_INET:
AixStructs.sockaddr_in sockaddrin =
(AixStructs.sockaddr_in)Marshal.PtrToStructure(curPos + 16, typeof(AixStructs.sockaddr_in));
var saddress = new IPAddress(sockaddrin.sin_addr);
if (address.Equals(saddress))
{
AixStructs.ifreq_addrin ifrMask = new AixStructs.ifreq_addrin();
unsafe {
ByteArrayCopy(ifrMask.ifr_name, ifr.ifr_name, 16);
}
// there's an IPv6 version of it too, but Mac OS doesn't try this, so
if (ioctl(sockfd, AixIoctlRequest.SIOCGIFNETMASK, ref ifrMask) < 0)
{
return(new IPAddress(ifrMask.ifru_addr.sin_addr));
}
else
{
throw new SystemException("ioctl for SIOCGIFNETMASK failed");
}
}
break;
default: break;
}
}
}
} finally {
if (ifc.ifc_buf != IntPtr.Zero)
{
Marshal.FreeHGlobal(ifc.ifc_buf);
}
if (sockfd != -1)
{
close(sockfd);
}
}
return(null);
}
