无法从主机名中找到 IP

Question

我有一个运行网络服务器的 wifi 传感器模块 (SN8200 EVK)。 该板被配置为作为 STA 工作并自动加入 WiFi 路由器。 传感器板使用主机名：“传感器”和 DHCP 接口来获取其 IP 地址。

我正在开发一个 Visual Studio C# 应用程序来连接到这个网络服务器。 该应用程序在连接到同一个 WiFi 路由器的笔记本电脑上运行。

传感器板 WiFi 路由器 笔记本电脑

如果我使用板 IP 地址，应用程序可以连接到传感器板。 由于 IP 地址不是静态的，我想使用主机名来检索 IP。

我尝试使用 GetHostEntry，但得到未知主机结果。

IPHostEntry host;
host = Dns.GetHostEntry("sensor");

奇怪的是，如果我将 GetHostEntry 与 IP 地址一起使用，它也无法解析主机名。

如果我尝试使用笔记本电脑主机名或 IP，GetHostEntry 工作正常。 看起来 GetHostEntry 无法解析路由器后面的主机名。

欢迎任何帮助， 谢谢。

Answer 1

静态IP解决方案

第一：

在您的 Wifi 路由器中配置 DHCP 服务器内的固定 IP 地址。
PS：我很确定 Mac 地址不是动态的

第二：

使用之前固定的 IP 地址在 DNS 服务器中添加主机名。

扫描网络的 IP 并检查 Mac 地址解决方案

在使用以下代码之前，您必须 ping 传感器板可以使用的整个 IP 范围以刷新您的 ARP 缓存。

using System;
using System.Runtime.InteropServices;
using System.ComponentModel;
using System.Net;
using System.Collections.Generic;

namespace GetIpNetTable
{
    class Program
    {
        static void Main(string[] args)
        {
            string[] ips = searchIpsFromMac("ff-ff-ff-ff-ff-ff");
            if (ips.Length != 0)
            {
                foreach (string ip in ips)
                {
                    // TODO - Do what you want with your IP address
                    Console.WriteLine(ip);
                }
            }
            Console.ReadKey();
        }

        // The max number of physical addresses.
        const int MAXLEN_PHYSADDR = 8;

        // Define the MIB_IPNETROW structure.
        [StructLayout(LayoutKind.Sequential)]
        struct MIB_IPNETROW
        {
            [MarshalAs(UnmanagedType.U4)]
            public int dwIndex;
            [MarshalAs(UnmanagedType.U4)]
            public int dwPhysAddrLen;
            [MarshalAs(UnmanagedType.U1)]
            public byte mac0;
            [MarshalAs(UnmanagedType.U1)]
            public byte mac1;
            [MarshalAs(UnmanagedType.U1)]
            public byte mac2;
            [MarshalAs(UnmanagedType.U1)]
            public byte mac3;
            [MarshalAs(UnmanagedType.U1)]
            public byte mac4;
            [MarshalAs(UnmanagedType.U1)]
            public byte mac5;
            [MarshalAs(UnmanagedType.U1)]
            public byte mac6;
            [MarshalAs(UnmanagedType.U1)]
            public byte mac7;
            [MarshalAs(UnmanagedType.U4)]
            public int dwAddr;
            [MarshalAs(UnmanagedType.U4)]
            public int dwType;
        }

        // Declare the GetIpNetTable function.
        [DllImport("IpHlpApi.dll")]
        [return: MarshalAs(UnmanagedType.U4)]
        static extern int GetIpNetTable(
           IntPtr pIpNetTable,
           [MarshalAs(UnmanagedType.U4)]
         ref int pdwSize,
           bool bOrder);

        [DllImport("IpHlpApi.dll", SetLastError = true, CharSet = CharSet.Auto)]
        internal static extern int FreeMibTable(IntPtr plpNetTable);

        // The insufficient buffer error.
        const int ERROR_INSUFFICIENT_BUFFER = 122;

        static string[] searchIpsFromMac(string macSearched)
        {
            List<string> ips = new List<string>(1);

            // The number of bytes needed.
            int bytesNeeded = 0;

            // The result from the API call.
            int result = GetIpNetTable(IntPtr.Zero, ref bytesNeeded, false);

            // Call the function, expecting an insufficient buffer.
            if (result != ERROR_INSUFFICIENT_BUFFER)
            {
                // Throw an exception.
                throw new Win32Exception(result);
            }

            // Allocate the memory, do it in a try/finally block, to ensure
            // that it is released.
            IntPtr buffer = IntPtr.Zero;

            // Try/finally.
            try
            {
                // Allocate the memory.
                buffer = Marshal.AllocCoTaskMem(bytesNeeded);

                // Make the call again. If it did not succeed, then
                // raise an error.
                result = GetIpNetTable(buffer, ref bytesNeeded, false);

                // If the result is not 0 (no error), then throw an exception.
                if (result != 0)
                {
                    // Throw an exception.
                    throw new Win32Exception(result);
                }

                // Now we have the buffer, we have to marshal it. We can read
                // the first 4 bytes to get the length of the buffer.
                int entries = Marshal.ReadInt32(buffer);

                // Increment the memory pointer by the size of the int.
                IntPtr currentBuffer = new IntPtr(buffer.ToInt64() +
                   Marshal.SizeOf(typeof(int)));

                // Allocate an array of entries.
                MIB_IPNETROW[] table = new MIB_IPNETROW[entries];

                // Cycle through the entries.
                for (int index = 0; index < entries; index++)
                {
                    // Call PtrToStructure, getting the structure information.
                    table[index] = (MIB_IPNETROW)Marshal.PtrToStructure(new
                       IntPtr(currentBuffer.ToInt64() + (index *
                       Marshal.SizeOf(typeof(MIB_IPNETROW)))), typeof(MIB_IPNETROW));
                }

                for (int index = 0; index < entries; index++)
                {
                    MIB_IPNETROW row = table[index];
                    IPAddress ip = new IPAddress(BitConverter.GetBytes(row.dwAddr));
                    string macAddr = row.mac0.ToString("X2") + '-' +
                        row.mac1.ToString("X2") + '-' +
                        row.mac2.ToString("X2") + '-' +
                        row.mac3.ToString("X2") + '-' +
                        row.mac4.ToString("X2") + '-' +
                        row.mac5.ToString("X2");
                    if (macAddr.ToUpper() == macSearched.ToUpper())
                    {
                        ips.Add(ip.ToString());
                    }
                }
            }
            finally
            {
                // Release the memory.
                FreeMibTable(buffer);
            }
            return ips.ToArray();
        }
    }
}

参考： https://stackoverflow.com/a/1148861/3635715