[转载]Linux网络编程IPv4和IPv6的inet_addr、inet_aton、inet_pton等函数小结

转载：http://blog.csdn.net/ithomer/article/details/6100734

知识背景：

210.25.132.181属于IP地址的ASCII表示法，也就是字符串形式。英语叫做IPv4 numbers-and-dots notation。
如果把210.25.132.181转换为整数形式，是3524887733，这个就是整数形式的IP地址。英语叫做binary data。（其实binary是二进制的意思）
详细介绍，请参考：网络字节序与主机字节序的转换

问题所在：

如何在字符串形式的IP和整数形式的IP之间转换呢？

转换函数：

int inet_aton(const char *cp, struct in_addr *inp);
in_addr_t inet_addr(const char *cp);
in_addr_t inet_network(const char *cp);
int inet_pton(int af, const char *src, void *dst);
const char *inet_ntop(int af, const void *src, char *dst, socklen_t cnt);

inet_ntopman.html

IPv4：

IP字符串 ——》网络字节流
inet_addr、inet_network、inet_aton

程序代码：

#include <stdio.h>  
#include <stdlib.h>  
#include <unistd.h>  
#include <string.h>  
#include <netinet/in.h>  
#include <sys/socket.h>  
#include <sys/types.h>  
  
int main()  
{  
    char ip[] = "192.168.0.74";  
    long r1, r2, r3;  //long  
    struct in_addr addr;  
  
    r1 = inet_addr(ip); //返回网络字节序  
    if(-1 == r1){  
        printf("inet_addr return -1/n");  
    }else{  
        printf("inet_addr ip: %ld/n", r1);  
    }  
      
    r2 = inet_network(ip);    //返回主机字节序  
    if(-1 == r2){  
        printf("inet_addr return -1/n");  
    }else{  
        printf("inet_network ip: %ld/n", r2);   
        printf("inet_network ip: %ld/n", ntohl(r2));   //ntohl: 主机字节序 ——> 网络字节序  
    }  
      
    r3 = inet_aton(ip, &addr);  //返回网络字节序  
    if(0 == r3){  
        printf("inet_aton return -1/n");  
    }else{  
        printf("inet_aton ip: %ld/n", addr.s_addr);  
    }  
  
/*****  批量注释的一种方法  *****/  
#if 0    
    r3 = inet_aton(ip, addr);  
    if(0 == r3){  
        printf("inet_aton return -1/n");  
    }else{  
        printf("inet_aton ip: %ld/n", ntohl(addr.s_addr));  
    }  
#endif  
  
    return 0;  
}

运行结果：

[work@db-testing-com06-vm3.db01.baidu.com net]$ gcc -W -o inet_addr inet_addr.c 
[work@db-testing-com06-vm3.db01.baidu.com net]$ ./inet_addr                     
inet_addr ip: 1241557184
inet_network ip: -1062731702
inet_network ip: 1241557184
inet_aton ip: 1241557184

IP字符串《——》网络字节流
inet_addr、inet_aton、inet_ntoa

程序代码：

[cpp] view plain copy print?
#include <stdio.h>  
#include <sys/socket.h>  
#include <netinet/in.h>  
#include <arpa/inet.h>  
#include <string.h>  
int main(int argc, char *argv[])  
{  
    char ip1[] = "192.168.0.74";  
    char ip2[] = "211.100.21.179";  
    struct in_addr addr1, addr2;  
    long l1, l2;  
    l1 = inet_addr(ip1);   //IP字符串——》网络字节  
    l2 = inet_addr(ip2);  
    printf("IP1: %s/nIP2: %s/n", ip1, ip2);  
    printf("Addr1: %ld/nAddr2: %ld/n", l1, l2);  
      
    memcpy(&addr1, &l1, 4); //复制4个字节大小  
    memcpy(&addr2, &l2, 4);  
    printf("%s <--> %s/n", inet_ntoa(addr1), inet_ntoa(addr2)); //注意：printf函数自右向左求值、覆盖  
    printf("%s/n", inet_ntoa(addr1)); //网络字节 ——》IP字符串  
    printf("%s/n", inet_ntoa(addr2));  
    return 0;  
}  
运行结果：
 
[work@db-testing-com06-vm3.db01.baidu.com net]$ gcc -W -o inet_ntoa inet_ntoa.c 
[work@db-testing-com06-vm3.db01.baidu.com net]$ ./inet_ntoa                                      
IP1: 192.168.0.74
IP2: 211.100.21.179
Addr1: 1241557184
Addr2: 3004523731
192.168.0.74 <--> 192.168.0.74
192.168.0.74
211.100.21.179

=============================================================

IPv6：

IPv4 字符串《——》网络字节流
inet_pton、inet_ntop

程序代码：

#include <stdio.h>  
#include <sys/types.h>  
#include <sys/socket.h>  
#include <arpa/inet.h>  
  
int main()  
{  
    char ip[] = "192.168.0.74";   
    struct in_addr addr;  
      
    int ret = inet_pton(AF_INET, ip, (void *)&addr);   //IP字符串 ——》网络字节流  
    if(0 == ret){  
        printf("inet_pton error, return 0/n");  
        return -1;  
    }else{  
        printf("inet_pton ip: %ld/n", addr.s_addr);  
        printf("inet_pton ip: 0x%x/n", addr.s_addr);  
    }  
  
    const char *pstr = inet_ntop(AF_INET, (void *)&addr, ip, 128);  //网络字节流 ——》IP字符串  
    if(NULL == pstr){  
        printf("inet_ntop error, return NULL/n");  
        return -1;  
    }else{  
        printf("inet_ntop ip: %s/n", ip);  
    }  
      
    return 0;  
}  
运行结果：
[work@db-testing-com06-vm3.db01.baidu.com net]$ gcc -W -o inet_ptoa inet_ptoa.c 
[work@db-testing-com06-vm3.db01.baidu.com net]$ ./inet_ptoa                     
inet_pton ip: 1241557184
inet_pton ip: 0x4a00a8c0
inet_ntop ip: 192.168.0.74

IPv6 字符串《——》网络字节流
inet_pton、inet_ntop

程序代码：

#include <stdio.h>  
#include <stdlib.h>  
#include <string.h>  
#include <arpa/inet.h>  
  
int   
main(int argc, char **argv)  
{  
    unsigned char buf[sizeof(struct in6_addr)];  
    int domain, s;  
    char str[INET6_ADDRSTRLEN];  
  
    if(argc != 3){  
        fprintf(stderr, "usage: %s {i4|i6|<num>} string/n", argv[0]);  
        exit(EXIT_FAILURE);  
    }  
  
    domain = (strcmp(argv[1], "i4") == 0) ? AF_INET:(strcmp(argv[1], "i6") == 0) ? AF_INET6 : atoi(argv[1]);  
      
    //IP字符串 ——》网络字节流  
    s = inet_pton(domain, argv[2], buf);  
    if(s<=0){  
        if(0 == s)  
            fprintf(stderr, "Not in presentation format/n");  
        else  
            perror("inet_pton");  
        exit(EXIT_FAILURE);  
    }  
  
    //网络字节流 ——》IP字符串  
    if(inet_ntop(domain, buf, str, INET6_ADDRSTRLEN) == NULL){    
        perror("inet ntop/n");  
        exit(EXIT_FAILURE);  
    }  
  
    printf("%s/n", str);  
    exit(EXIT_SUCCESS);  
}

运行结果：
[work@db-testing-com06-vm3.db01.baidu.com net]$ gcc -W -o inet_ptoa6 inet_ptoa6.c
[work@db-testing-com06-vm3.db01.baidu.com net]$ ./inet_ptoa6 i6 0:0:0:0:0:FFFF:204.152.189.116
::ffff:204.152.189.116
[work@db-testing-com06-vm3.db01.baidu.com net]$ ./inet_ptoa6 i4 204.152.189.116
204.152.189.116