Linux C Network Programming-Get local IP address, mac, get corresponding IP via domain name

Get the local IP address, Mac, get the corresponding IP through the domain name,

Is the more common operation that network programming may encounter, so it is summarized as follows (3 functions are encapsulated),

Directly on the code :

#include <stdio.h> #include <stdlib.h> #include <string.h> #include <errno.h> #include < unistd.h> #include <netdb.h> #include <net/if.h> #include <arpa/inet.h> #include <sys/ioctl.h > #include <sys/types.h> #include <sys/socket.h> #define Mac_size18#define ip_size16//function Declareint get_ip_by_domain (const char *domain, char *ip); Gets Ipint get_local_mac (const char *eth_inf, char *mac) according to the domain name; Gets the native Macint get_local_ip (const char *eth_inf, char *ip); Gets the native ip/****** main test **********/int main (void) {char Ip[ip_size];char mac[mac_size];const char *test_domain = "www.b Aidu.com "; const char *test_eth =" eth0 "; Get_ip_by_domain (Test_domain, IP);p rintf ("%s IP:%s\n ", Test_domain, IP); get_ Local_mac (Test_eth, Mac);p rintf ("Local%s Mac:%s\n", Test_eth, Mac), Get_local_ip (Test_eth, IP);p rintf ("Local%s IP:%s\ N ", Test_eth, IP); return 0;} Get Ipint get_ip_by_domain (const char *domain, char *ip) based on domain name {char **pptr;struct hostent *hptr;hptr =gethostbyname (domain), if (NULL = = hptr) {printf ("GetHostByName error for host:%s/n", domain); return-1;} for (pptr = hptr->h_addr_list; *pptr! = null; pptr++) {if (Null! = Inet_ntop (Hptr->h_addrtype, *pptr, IP, ip_size)) { return 0; Get only the first ip}}return-1;} Get native Macint get_local_mac (const char *eth_inf, char *mac) {struct ifreq ifr;int sd;bzero (&ifr, sizeof (struct ifreq)) ; if (SD = socket (af_inet, sock_stream, 0)) < 0) {printf ("Get%s MAC address socket creat error\n", eth_inf); return-1;} strncpy (Ifr.ifr_name, Eth_inf, sizeof (Ifr.ifr_name)-1), if (IOCTL (SD, SIOCGIFHWADDR, &AMP;IFR) < 0) {printf ("Get%s MAC address error\n ", eth_inf); return-1;} snprintf (Mac, Mac_size, "%02x:%02x:%02x:%02x:%02x:%02x", (unsigned char) ifr.ifr_hwaddr.sa_data[0], (unsigned char) IFR.IFR_HWADDR.SA_DATA[1], (unsigned char) ifr.ifr_hwaddr.sa_data[2], (unsigned char) ifr.ifr_hwaddr.sa_data[3], ( unsigned char) ifr.ifr_hwaddr.sa_data[4], (unsigned char) ifr.ifr_hwaddr.sa_data[5]); close (SD); return 0;} Get native IpintGET_LOCAL_IP (const char *eth_inf, char *ip) {int sd;struct sockaddr_in sin;struct ifreq ifr;sd = socket (Af_inet, SOCK_DGRAM , 0); if ( -1 = = SD) {printf ("Socket Error:%s\n", Strerror (errno)); return-1;} strncpy (Ifr.ifr_name, Eth_inf, Ifnamsiz); ifr.ifr_name[ifnamsiz-1] = 0;//if error:no such Deviceif (IOCTL (SD, SIOCGIFAD DR, &AMP;IFR) < 0) {printf ("IOCTL error:%s\n", Strerror (errno)); Close (SD); return-1;} memcpy (&sin, &ifr.ifr_addr, sizeof (SIN)), snprintf (IP, ip_size, "%s", Inet_ntoa (SIN.SIN_ADDR)), close (SD); return 0;}

Test RunThe results are as follows:

Linux C Network Programming-Get local IP address, mac, get corresponding IP via domain name