本文使用getifaddrs 函数获取网卡的IP和MAC地址。getifaddrs函数有个特点，就是获取地址时以链表方式返回，且每个链表节点要么是IP，要么是MAC，所以如果要将网卡的IP和MAC地址同时返回的话，需要对对返回链表进行查找和重新组合。本文实现目的，在于以网卡名方式返回IP和MAC地址。代码如下：
#ifndef _MYLIB_H #define _MYLIB_H #include <stdlib.h> #include <errno.h> #define error_report(msg) \ do { perror(msg); \ exit (EXIT_FAILURE) \ }while (0) //clean the stdin cach void clean_cach (void); //get a string from stdin int getstring (char *str, int num); /* define a get if info struct */ struct if_ipv4_info { char if_name[10];; unsigned char ip_addr[20]; unsigned char hd_addr[20]; struct if_ipv4_info *next; }; #endif 函数实现 #include <sys/types.h> #include <sys/socket.h> #include <string.h> #include <netinet/in.h> #include <ifaddrs.h> #include <net/ethernet.h> #include <stdio.h> #include <stdlib.h> #include <netpacket/packet.h> #include <net/ethernet.h> #include <errno.h> #include <netinet/in.h> #include <netinet/ip.h> #include "mylib.h" #define DEBUG 0 struct if_ipv4_info *if_info = NULL; /* ** add ip to a linklist */ static int add_to_link (struct ifaddrs *ifap, char *buf) { struct if_ipv4_info *p, *q; if (if_info == NULL) { if_info = malloc (sizeof (struct if_ipv4_info)); /* init head */ if_info->next = NULL; if_info->ip_addr[0] = \'\0\'; if_info->hd_addr[0] = \'\0\'; if (if_info == NULL) { fprintf (stderr, "malloc failed\n"); exit (EXIT_FAILURE); } strcpy (if_info->if_name, ifap->ifa_name); switch (ifap->ifa_addr->sa_family) { case AF_INET: strcpy (if_info->ip_addr, buf); // printf ("head %s", if_info->ip_addr); break; case AF_PACKET: strcpy (if_info->hd_addr, buf); // printf ("head %s", if_info->hd_addr); break; default: break; } //switch }else { for (p = if_info; p != NULL; p = p->next) { q = p; if (strcmp (p->if_name, ifap->ifa_name) == 0) { break; } } if (p != NULL) { switch (ifap->ifa_addr->sa_family) { case AF_INET: strcpy (p->ip_addr, buf); // printf ("p %s\n", p->ip_addr); break; case AF_PACKET: strcpy (p->hd_addr, buf); // printf ("p %s\n", p->hd_addr); break; default: break; } //switch } else { p = malloc (sizeof (struct if_ipv4_info)); /* init node */ p->next = NULL; p->ip_addr[0] = \'\0\'; p->hd_addr[0] = \'\0\'; if (p == NULL) { fprintf (stderr, "malloc failled"); exit (EXIT_FAILURE); } strcpy (p->if_name, ifap->ifa_name); switch (ifap->ifa_addr->sa_family) { case AF_INET: strcpy (p->ip_addr, buf); // printf ( "else p %s\n", p->ip_addr); break; case AF_PACKET: strcpy (p->hd_addr, buf); //printf ( "else p %s\n", p->hd_addr); break; default: break; } q->next = p; }//else } return 0; } int prt_if_info (struct sockaddr *ifa_addr, char *addrbuf, int bufsize) { memset (addrbuf, 0, bufsize); struct sockaddr_ll *s; int i; int len; int family = ifa_addr->sa_family; int ret = 0; switch (family) { case AF_INET: inet_ntop (ifa_addr->sa_family, &((struct sockaddr_in *)ifa_addr)->sin_addr, addrbuf, sizeof (struct sockaddr_in)); break; case AF_PACKET: s = (struct sockaddr_ll *)ifa_addr; for (i=0,len=0; i<6; i++) { len += sprintf (addrbuf+len, "%02x%s", s->sll_addr[i], i<5?":":" "); } break; default: ret = -1; break; } return ret; } int get_if_info (void) { struct ifaddrs *ifa, *ifap; int family; /* protocl family */ if (getifaddrs (&ifa) == -1) { perror (" getifaddrs\n"); exit (EXIT_FAILURE); } char buf[20]; for (ifap = ifa; ifap != NULL; ifap = ifap->ifa_next) { if (strcmp (ifap->ifa_name, "lo") == 0) { continue; /* skip the lookback card */ } if (ifap->ifa_addr == NULL) continue; /* if addr is NULL, this must be no ip address */ if (prt_if_info (ifap->ifa_addr, buf, 20) == 0) { // printf ("%s: %s\n", ifap->ifa_name, buf); add_to_link (ifap, buf); } } /* printf all of them */ struct if_ipv4_info *p = NULL; for (p = if_info; p != NULL; p = p->next) { printf ("%s: %s\t%s\n", p->if_name, strlen(p->ip_addr)>0?p->ip_addr: "No ip addr", p->hd_addr); } /* free link list */ struct if_ipv4_info *q = NULL; for (p = if_info; p != NULL; ) { q = p; p = p->next; free (q); } freeifaddrs (ifa); return 0; } /* ** test code */ int main (int argc, char **argv) { get_if_info (); return 0; }