// Title: display_ip_address.c// Purpose: Display IP, Netmask, Broadcast, and MAC//--------------------------------------------------------// REFERENCES:// http://www.beej.us/guide/bgnet/output/html/multipage/structs.html// http://www.basepath.com/aup/ex/structsockaddr__in.html// http://www.gsp.com/cgi-bin/man.cgi?section=3&topic=getifaddrs// http://www.hmug.org/man/3/getifaddrs.php//--------------------------------------------------------#include <stdio.h> /* standard io headers */#include <stdlib.h>#include <string.h>#include <sys/types.h>#include <sys/socket.h> /* defines sturct addr_sockaddr_in */#include <netinet/in.h>#include <arpa/inet.h>#include <ifaddrs.h> /* getifaddrs() */#include <netinet/ether.h> /* ether_ntoa() */#include <netpacket/packet.h> /* struct sockaddr_ll */#define MY_INTERFACE "ath0"#define DEBUG 1//--------------------------------------------------------//int main(){ struct ifaddrs *id; // linked list of structs (id->ifa_next points to next element) struct sockaddr_in *addr_sockaddr_in; // sockaddr_in has an in_addr member struct sockaddr_in *netmask_sockaddr_in; // sockaddr_in has an ifa_netmask member struct ether_addr *mac_ether_addr; // ether_addr, cast to struct sockaddr_ll *mac_sockaddr_ll; // struct sockaddr_ll *ip_sockaddr_ll = (struct sockaddr_ll *)(id->ifa_addr); char *ascii_ip_address; // holds 'dots-and-number' ip address char *ascii_netmask_address; // holds 'dots-and-number' netmask address char *ascii_broadcast_address; // holds 'dots-and-number' broadcast address char *ascii_mac_address; // hods the 'colon-and-numbers' mac address char *ascii_interface; // holds name of the network interface int val; // socket descriptor is junst an int val = getifaddrs(&id); // getifaddrs function stores a reference to a linked list of the network interfaces // for ( ; id != NULL ; id = id->ifa_next) // Loop through all interfaces known to getifaddrs // enter section below, // then point to next struct in linked list { if ( id->ifa_addr != NULL ) // ifa_addr contains either interface address OR link level address OR NULL { if ( id->ifa_addr->sa_family == AF_INET ) // "AF_INET" means internetwork: UDP, TCP, etc. */ { if ( strcmp(id->ifa_name, MY_INTERFACE) == 0 ) // if 'id->ifa_name' is MY_INTERFACE,enter section { ascii_interface=id->ifa_name; // Output interface name string if( DEBUG ) { printf("Interface: %s\n", ascii_interface); // Output the 'dots-and-number' ip } //--------------------------------------------------------// // IP // //--------------------------------------------------------// addr_sockaddr_in = (struct sockaddr_in *)(id->ifa_addr); // cast struct sockaddr to struct sockaddr_in, // sockaddr_in has an ifa_addr member, but sockaddr doesn't ascii_ip_address = inet_ntoa( addr_sockaddr_in->sin_addr ); // convert socket ip to 'dots-and-number' ip if( DEBUG ) { printf("IP Address: %s\n", ascii_ip_address); // Output the 'dots-and-number' ip } //--------------------------------------------------------// // Netmask //--------------------------------------------------------// if ( id->ifa_netmask != NULL ) // checking for null before processing. { netmask_sockaddr_in = (struct sockaddr_in *)(id->ifa_netmask); // cast struct sockaddr to be struct sockaddr_in, // sockaddr_in has an ifa_netmask member, but sockaddr doesn't ascii_netmask_address = inet_ntoa( netmask_sockaddr_in->sin_addr ); // convert socket ip to 'dots-and-number' ip if( DEBUG ) { printf("Netmask: %s\n", ascii_netmask_address); // Output the 'dots-and-number' netmask } } //--------------------------------------------------------// // Broadcast //--------------------------------------------------------// if ( id->ifa_broadaddr != NULL ) // checking for null before processing. { netmask_sockaddr_in = (struct sockaddr_in *)(id->ifa_broadaddr); // cat struct sockaddr to be sturct sockaddr_in, ascii_broadcast_address = inet_ntoa( netmask_sockaddr_in->sin_addr ); // struct sockaddr_in has an ifa_broadaddr member, // but sockaddr doesn't if( DEBUG ) { printf("Broadcast: %s\n", ascii_broadcast_address); // Output the 'dots-and-number' broadcast } } } } } //--------------------------------------------------------// // MAC //--------------------------------------------------------// if ( id->ifa_addr->sa_family == AF_PACKET ) // "AF_PACKET" contains the mac { //if ( strcmp(id->ifa_name, "lo") != 0 ) // if 'id->ifa_name' is not loopback (lo),enter section if ( strcmp(id->ifa_name, MY_INTERFACE ) == 0 ) // if 'id->ifa_name' is MY_INTERFACE,enter section { mac_sockaddr_ll = (struct sockaddr_ll *)(id->ifa_addr); // cast struct sockaddr to be struct sockaddr_ll // sockaddr_ll has member sll_addr (the mac) if ( mac_sockaddr_ll->sll_hatype == ARPHRD_ETHER) // check for correct hatype to have a mac { ascii_mac_address = ether_ntoa((struct ether_addr *)(mac_sockaddr_ll->sll_addr)); // cast sturct sockaddr_ll to struct ether_addr // ether_ntoa only works on struct ether_addr if( DEBUG ) { printf("MAC: %s\n", ascii_mac_address); // Output the 'dots-and-number' mac } } } //break; // Just grab first interface //printf("\n"); // Print all interfaces } } // should run freeifaddrs(); freeifaddrs (id); printf("%s %s %s %s %s\n", ascii_interface, ascii_ip_address, ascii_netmask_address, ascii_broadcast_address, ascii_mac_address); return 0;}