System.Net.Sockets.SocketPal.ReceiveMessageFrom C# (CSharp) Method

        private static unsafe int ReceiveMessageFrom(SafeCloseSocket socket, SocketFlags flags, byte[] buffer, int offset, int count, byte[] socketAddress, ref int socketAddressLen, bool isIPv4, bool isIPv6, out SocketFlags receivedFlags, out IPPacketInformation ipPacketInformation, out Interop.Error errno)
        {
            Debug.Assert(socketAddress != null, "Expected non-null socketAddress");

            int cmsgBufferLen = Interop.Sys.GetControlMessageBufferSize(isIPv4, isIPv6);
            var cmsgBuffer = stackalloc byte[cmsgBufferLen];

            int sockAddrLen = socketAddressLen;

            Interop.Sys.MessageHeader messageHeader;

            long received;
            fixed (byte* rawSocketAddress = socketAddress)
            fixed (byte* b = buffer)
            {
                var sockAddr = (byte*)rawSocketAddress;

                var iov = new Interop.Sys.IOVector {
                    Base = &b[offset],
                    Count = (UIntPtr)count
                };

                messageHeader = new Interop.Sys.MessageHeader {
                    SocketAddress = sockAddr,
                    SocketAddressLen = sockAddrLen,
                    IOVectors = &iov,
                    IOVectorCount = 1,
                    ControlBuffer = cmsgBuffer,
                    ControlBufferLen = cmsgBufferLen
                };

                errno = Interop.Sys.ReceiveMessage(socket, &messageHeader, flags, &received);
                receivedFlags = messageHeader.Flags;
                sockAddrLen = messageHeader.SocketAddressLen;
            }

            ipPacketInformation = GetIPPacketInformation(&messageHeader, isIPv4, isIPv6);

            if (errno != Interop.Error.SUCCESS)
            {
                return -1;
            }

            socketAddressLen = sockAddrLen;
            return checked((int)received);
        }