c# – 如何在Linux上使用Mono查询子网掩码？教程

在我在开放式嵌入式Linux上运行的应用程序(用MVC3编写的管理Web界面)中,我必须列出所有TCP / IP设置.这包括IP-Adresse,Gateway和子网掩码.

以下代码在MS .Net下运行良好,但Mono 2.10为“IPv4Mask”属性抛出NotImplemntedException：

var ipProperties = networkIntf.GetIPProperties(); 
var unicastIpInfo = ipProperties.UnicastAddresses.FirstOrDefault(); 
var subnetMask = unicastAddress != null ? unicastAddress.IPv4Mask.ToString() : ""; 

有人知道如何使用Mono获得IPv4子网掩码吗？

我发现这个问题已在2009年问过,但未找到任何答案.

解决方法:

我看了一些Mono源代码并提取了一些代码片段来构建一个帮助器,它返回给定网络接口的IPv4子网掩码.代码不是绝对的美,但它的工作原理.

[StructLayout(LayoutKind.Explicit)]
struct ifa_ifu
{
    [FieldOffset(0)]
    public IntPtr ifu_broadaddr;

    [FieldOffset(0)]
    public IntPtr ifu_dstaddr;
}

[StructLayout(LayoutKind.Sequential)]
struct ifaddrs
{
    public IntPtr ifa_next;
    public string ifa_name;
    public uint ifa_flags;
    public IntPtr ifa_addr;
    public IntPtr ifa_netmask;
    public ifa_ifu ifa_ifu;
    public IntPtr ifa_data;
}

[StructLayout(LayoutKind.Sequential)]
struct sockaddr_in
{
    public ushort sin_family;
    public ushort sin_port;
    public uint sin_addr;
}

[StructLayout(LayoutKind.Sequential)]
struct sockaddr_in6
{
    public ushort sin6_family;   /* AF_INET6 */
    public ushort sin6_port;     /* Transport layer port # */
    public uint sin6_flowinfo; /* IPv6 flow information */
    public in6_addr sin6_addr;     /* IPv6 address */
    public uint sin6_scope_id; /* scope id (new in RFC2553) */
}

[StructLayout(LayoutKind.Sequential)]
struct in6_addr
{
    [MarshalAs(UnmanagedType.ByValArray, SizeConst = 16)]
    public byte[] u6_addr8;
}

[StructLayout(LayoutKind.Sequential)]
struct sockaddr_ll
{
    public ushort sll_family;
    public ushort sll_protocol;
    public int sll_ifindex;
    public ushort sll_hatype;
    public byte sll_pkttype;
    public byte sll_halen;

    [MarshalAs(UnmanagedType.ByValArray, SizeConst = 8)]
    public byte[] sll_addr;
}

internal class IPInfoTools
{
    const int AF_INET = 2;
    const int AF_INET6 = 10;
    const int AF_PACKET = 17;

    [DllImport("libc")]
    static extern int getifaddrs (out IntPtr ifap);

    [DllImport ("libc")]
    static extern void freeifaddrs (IntPtr ifap);

    internal static string GetIPv4Mask(string networkInterfaceName)
    {
        IntPtr ifap;
        if (getifaddrs(out ifap) != 0)
        {
            throw new SystemException("getifaddrs() failed");
        }

        try
        {
            var next = ifap;
            while (next != IntPtr.Zero)
            {
                var addr = (ifaddrs)Marshal.PtrToStructure(next, typeof(ifaddrs));
                var name = addr.ifa_name;

                if (addr.ifa_addr != IntPtr.Zero)
                {
                    var sockaddr = (sockaddr_in)Marshal.PtrToStructure(addr.ifa_addr, typeof(sockaddr_in));
                    switch (sockaddr.sin_family)
                    {
                        case AF_INET6:
                            //sockaddr_in6 sockaddr6 = (sockaddr_in6)Marshal.PtrToStructure(addr.ifa_addr, typeof(sockaddr_in6));
                            break;
                        case AF_INET:
                            if (name == networkInterfaceName)
                            {
                                var netmask = (sockaddr_in)Marshal.PtrToStructure(addr.ifa_netmask, typeof(sockaddr_in));
                                var ipAddr = new IPAddress(netmask.sin_addr);  // IPAddress to format into default string notation
                                return ipAddr.ToString();
                            }
                            break;
                        case AF_PACKET:
                            {
                                var sockaddrll = (sockaddr_ll)Marshal.PtrToStructure(addr.ifa_addr, typeof(sockaddr_ll));
                                if (sockaddrll.sll_halen > sockaddrll.sll_addr.Length)
                                {
                                    Console.Error.WriteLine("Got a bad hardware address length for an AF_PACKET {0} {1}",
                                                            sockaddrll.sll_halen, sockaddrll.sll_addr.Length);
                                    next = addr.ifa_next;
                                    continue;
                                }
                            }
                            break;
                    }
                }

                next = addr.ifa_next;
            }
        }
        finally
        {
            freeifaddrs(ifap);
        }

        return null;
    }
}

上面帮手的用法是这样的：

String subnetMask = IPInfoTools.GetIPv4Mask("etc0");

我还没有设法在Mono源代码中解决这个问题,因为需要在Mono中更改一些文件,以便从查询它的位置(LinuxNetworkInterface)获取上述信息到它所使用的位置(LinuxUnicastIPAddressInfo).但我会将我的代码发布到Mono错误报告中,所以也许Mono开发人员可以看一下.