参考：https://zhidao.baidu.com/question/191740827.html

私有IP地址范围：

A: 10.0.0.0 10.255.255.255 10.0.0.0/8

B: 172.16.0.0 172.31.255.255 172.16.0.0/12

C: 192.168.0.0 192.168.255.255 192.168.0.0/16

在C语言中的 socket 结构体如下

struct sockaddr_in {    short   sin_family;    USHORT  sin_port;    IN_ADDR sin_addr;    CHAR sin_zero[8];}

 

其中IP 地址字段为 sin_addr，当选择IPv4类型的IP地址时，sin_addr 是一个网络字节序的4字节的数字。

sample:

192.168.207.1

c0 a8 cf 01

Filter:

A: startwith 10.x.x.x

B: startwith 172.(16~31).x.x

C: startwith 192.168.x.x

判断顺序:

A -> C -> B

伪码如下：

char data[4] = NetworkAddr;

 

if data[0] == 10:

　　return true

elif data[0] == 192 and data[1] == 168:

　　return true

elif data[0] == 172:

　　if data[1] >= 16 and data[1] <= 31:

　　　　return true

else:

　　return False

 

#include 
     
      #include 
      
       #include 
       
        #pragma comment(lib,"ws2_32.lib")        // inet_addr()BOOL isLocalAddr(DWORD    netAddr){    unsigned char    data[4];    BOOL    bRet = FALSE;    memcpy(data, (char *)&netAddr, 4);        if (10 == data[0])    {        bRet = TRUE;    }    else if (192 == data[0] && 168 == data[1])    {        bRet = TRUE;    }    else if (172 == data[0])    {        if (data[1] >= 16 && data[1] <= 31)        {            bRet = TRUE;        }    }    else if(!memcmp(data, servAddr, 4))    {        bRet = TRUE;    }    return bRet;}int main(){    char    *addrList[] = {        "192.168.207.1",        "192.12.1.3",        "172.16.2.1",        "172.33.1.1",        "10.12.12.1",        "43.1.31.23",    };    char    *result[] = {        "X Local Address",        "O Local Address"    };    int        addrCnt = sizeof(addrList) / sizeof(addrList[0]);    DWORD    netAddr = 0;    BOOL    ret = FALSE;    for (int i = 0; i < addrCnt; i++)    {        netAddr = inet_addr(addrList[i]);        ret = isLocalAddr(netAddr);        printf("%-16s [%s]\n", addrList[i], result[ret]);    }    return 0;}
       
      
     

 

运行结果：