通过建立好连接的ｓｏｃｋｅｔ或者ＩＰ获取对端ＭＡＣ地址

#include <stdio.h>
#include <stdlib.h>
#include <errno.h>
#include <string.h>
#include <sys/types.h>
#include <netinet/in.h>
#include <sys/socket.h>
#include <sys/wait.h>
#include <sys/ioctl.h>
#include <net/if.h>
#include <netinet/in.h>
#include <net/if_arp.h>
#include <unistd.h>
#include <arpa/inet.h>
#include <pthread.h>

int getPeerMacbySocketFd( int sockfd, char *buf, char* localethname )
{
int ret =0;
struct arpreq arpreq;
struct sockaddr_in dstadd_in;
socklen_t len = sizeof( struct sockaddr_in );
memset( &arpreq, 0, sizeof( struct arpreq ));
memset( &dstadd_in, 0, sizeof( struct sockaddr_in ));
if( getpeername( sockfd, (struct sockaddr*)&dstadd_in, &len ) < 0 )
{
perror( "get peer name wrong, %s/n", strerror(errno) );
return -1;
}
else
{
memcpy( ( struct sockaddr_in * )&arpreq.arp_pa, ( struct sockaddr_in * )&dstadd_in, sizeof( struct sockaddr_in ));
strcpy(arpreq.arp_dev, localethname);
arpreq.arp_pa.sa_family = AF_INET;
arpreq.arp_ha.sa_family = AF_UNSPEC;
if( ioctl( sockfd, SIOCGARP, &arpreq ) < 0 )
{
perror( "ioctl SIOCGARP wrong, %s/n", strerror(errno) );
return -1;
}
else
{
unsigned char* ptr = (unsigned char *)arpreq.arp_ha.sa_data;
sprintf(buf, "%02x:%02x:%02x:%02x:%02x:%02x", *ptr, *(ptr+1), *(ptr+2), *(ptr+3), *(ptr+4), *(ptr+5));
}
}
return ret;
}

int gahGetPeerMacbyIp(char *ipaddr, char* buf, char* localethname)
{
int sockfd;
unsigned char *ptr;
struct arpreq arpreq;
struct sockaddr_in *sin;
struct sockaddr_storage ss;
char addr[INET_ADDRSTRLEN+1];

memset(addr, 0, INET_ADDRSTRLEN+1);
memset(&ss, 0, sizeof(ss));

sockfd = socket(AF_INET, SOCK_DGRAM, 0);
if (sockfd == -1) {
trace(3, "socket error");
return -1;
}
sin = (struct sockaddr_in *) &ss;
sin->sin_family = AF_INET;
if (inet_pton(AF_INET, ipaddr, &(sin->sin_addr)) <= 0) {
trace(3, "inet_pton error");
return -1;
}
sin = (struct sockaddr_in *) &arpreq.arp_pa;
memcpy(sin, &ss, sizeof(struct sockaddr_in));
strcpy(arpreq.arp_dev, localethname);
arpreq.arp_ha.sa_family = AF_UNSPEC;
if (ioctl(sockfd, SIOCGARP, &arpreq) < 0) {
trace(3, "ioctl SIOCGARP: ");
return -1;
}
ptr = (unsigned char *)arpreq.arp_ha.sa_data;
sprintf(buf,"%02x:%02x:%02x:%02x:%02x:%02x", *ptr, *(ptr+1), *(ptr+2), *(ptr+3), *(ptr+4), *(ptr+5));
return 0;
}