IP地址转换函数例子

1、socket类型说明和地址转换函数例子

#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <stdio.h>
#include <string.h>
#if 0
typedef uint32_t in_addr_t

typedef unsigned short sa_family_t;
#define __CONST_SOCKADDR_ARG  __const struct sockaddr *
#define __SOCKADDR_COMMON(sa_prefix) sa_family_t sa_prefix##family
#define __SOCKADDR_COMMON_SIZE (sizeof (unsigned short int))
typedef uint16_t in_port_t; /* Type to represent a port. */
struct in_addr { /* struct in_addr其实就是32位IP地址 */
        unsigned long s_addr;
};

struct sockaddr {
        sa_family_t     sa_family; /* address family, AF_xxx */
        char            sa_data[14]; /* 14 bytes of protocol address */
}
struct sockaddr_in
{
    __SOCKADDR_COMMON (sin_);
    in_port_t sin_port; /* Port number. */
    struct in_addr sin_addr; /* Internet address. */
    /* 字符数组sin_zero[8]的存在是为了保证结构体struct sockaddr_in的大小
       和结构体struct sockaddr的大小相等
     */
    /* Pad to size of `struct sockaddr'. */
    unsigned char sin_zero[sizeof (struct sockaddr) -
                           __SOCKADDR_COMMON_SIZE -
                           sizeof (in_port_t) -
                           sizeof (struct in_addr)];
};
#endif

int main(int argc, char *argv[])
{
    in_addr_t net;
    in_addr_t hostID, netID;
    struct in_addr NetHostAddr;
    struct in_addr net_addr, ret;
    char buf[128];
    /*1、IPv4地址转换 */
    /* 1.1、32位与点分十进制转换 */
    net = inet_addr("192.168.3.1");//转换为网络字节顺序
    net_addr.s_addr = net;
    printf("inet_ntoa:%s\n", inet_ntoa(net_addr));

    inet_aton("192.168.3.2", &ret);
    printf("ret.s_addr=%x\n", ret.s_addr);
    printf("inet_ntoa:%s\n", inet_ntoa(ret));
    printf("\n");

    /* 1.2、点分十进制转换为32位*/
    net = inet_addr("192.168.3.1");//点分十进制转换为32位网络字节顺序
    printf("inet_addr(192.168.3.1)=0x%x %02x %02x %02x %02x \n", net, net>>24&0xff, net>>16&0xff, net>>8&0xff, net&0xff);
    net = inet_network("192.168.3.1");//点分十进制转换为32位主机字节顺序
    printf("inet_network(192.168.3.1)=0x%x %02x %02x %02x %02x \n", net, net>>24&0xff, net>>16&0xff, net>>8&0xff, net&0xff);

    /*3、基于地址类型转换 */
    inet_pton(AF_INET, "192.168.3.10", &ret);
    inet_ntop(AF_INET, &ret, buf, 128);
    printf("buf=%s\n",buf);

    /*4、通过IP地址获取网络ID和主机ID */
    inet_aton("192.168.3.4", &NetHostAddr);
    printf("\nNetHostAddr.s_addr=%x\n", NetHostAddr.s_addr);
    hostID = inet_lnaof(NetHostAddr);//提取主机ID
    printf("inet_lnaof:%x\n", hostID);
    netID = inet_netof(NetHostAddr);
    printf("inet_netof:%x\n", netID);
    NetHostAddr = inet_makeaddr(netID, hostID);
    printf("inet_makeaddr:%x\n", NetHostAddr.s_addr);
}