获取IP地址函数（本地、域名转换）

获取IP地址函数（本地、域名转换）

作者: falcon   发表日期: 2006-09-27 15:27   复制链接

　前些天由于项目需要，自己整了一个比较全面的获取IP地址的函数：
　　可以获取本地的IP地址，也可以根据域名获取IP地址，感觉比较有用特此奉献上，呵呵。

　　下面是源代码

Code:
/* GetIp.c -- Get Local or remote Ip address by domain name  * Designed by falcon, 2006-9-16, Email: zhangjinw[at]gmail.com  * */ #include <sys/socket.h> #include <sys/ioctl.h> #include <net/if.h> #include <netdb.h> #include <string.h> #include <errno.h> #define h_addr h_addr_list[0] char * GetIp(char *dn_or_ip) {         struct sockaddr_in addr;         struct hostent *host;         struct ifreq req;         int sock;         if (dn_or_ip == NULL) return NULL;         if (strcmp(dn_or_ip, "localhost") == 0) {                 sock = socket(AF_INET, SOCK_DGRAM, 0);                 strncpy(req.ifr_name, "eth0", IFNAMSIZ);                 if ( ioctl(sock, SIOCGIFADDR, &req) < 0 ) {                         printf("ioctl error: %s\n", strerror (errno));                         return NULL;                 }                 dn_or_ip = (char *)inet_ntoa(*(struct in_addr *) &((struct sockaddr_in *) &req.ifr_addr)->sin_addr);                 shutdown(sock, 2);                 close(sock);         } else {                 host = gethostbyname(dn_or_ip);                 if (host == NULL) return NULL;                 dn_or_ip = (char *)inet_ntoa(*(struct in_addr *)(host->h_addr));         }         return dn_or_ip; }
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　　下面是一个测试的代码
test_GetIp.c

Code:
/*test_GetIp.c*/ #include <stdio.h> #include "GetIp.c" int main(int argc, char *argv[]) {         if (argc < 2) {                 fprintf(stderr, "Usage: %s domain_name or ip_address\n", argv[0]);                 return -1;         }         char *current_ip_address;         current_ip_address = NULL;         if ((current_ip_address = GetIp( argv[1])) == NULL) {                 printf ("Ip address convert error!\n");                 return -1;         } else {                 printf("domain name or ip address : %s\n", argv[1]);                 printf("current ip address: %s\n", current_ip_address);         }         return 0; }
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　　具体使用演示
引文:

$./test_GetIp xxxy.lzu.edu.cn --这里是根据域名转换为IP地址
domain name or ip address : xxxy.lzu.edu.cn
current ip address: 202.201.0.237

$ ./test_GetIp 219.246.79.7　--输入地址返回地址
domain name or ip address : 219.246.79.7
current ip address: 219.246.79.7

$ ./test_GetIp localhost　　--获取本地IP地址
domain name or ip address : localhost
current ip address: 219.246.79.4