tcp4_10localip.c

LinuxNetProgramming Linux网络编程基础实例

/* tcp4_10localip.c */
#include <stdio.h> 
#include <string.h> 
#include <netdb.h> 
#include <arpa/inet.h> 
#include <netinet/in.h> 
#include <sys/types.h> 
#include <sys/socket.h> 
#include <sys/ioctl.h> 
#include <net/if.h> 
#include <net/if_arp.h> 
#include <net/ethernet.h> 
#include <signal.h> 
#include <netinet/ip.h> 

struct  in_addr myself, mymask; 
int fd_arp;                 /* socket fd for receive packets */ 
struct  ifreq  ifr;            /* ifr structure */ 
main (int argc, char* argv[]) { 
    char device[32];  /* ethernet device name */ 
    struct sockaddr  from, to; 
    int fromlen; 
    struct sockaddr_in *sin_ptr; 
    u_char *ptr; 
    int n; 
    strcpy(device, "eth0"); 
    if ((fd_arp = socket(AF_INET, SOCK_PACKET, htons(0x0806))) < 0) { 
        perror( "arp socket error"); 
        exit(-1); 
    } 

    strcpy(ifr.ifr_name, device); 
    /* ifr.ifr_addr.sa_family = AF_INET; */ 
    /* get ip address of my interface */ 
    if (ioctl(fd_arp, SIOCGIFADDR, &ifr) < 0) { 
        perror("ioctl SIOCGIFADDR error"); 
        exit(-1); 
    } 
    sin_ptr = (struct sockaddr_in *)&ifr.ifr_addr; 
    myself  = sin_ptr->sin_addr; 
    /* get network mask of my interface */ 
    if (ioctl(fd_arp, SIOCGIFNETMASK, &ifr) < 0) { 
        perror("ioctl SIOCGIFNETMASK error"); 
        exit(-1); 
    } 
    sin_ptr = (struct sockaddr_in *)&ifr.ifr_addr; 
    mymask  = sin_ptr->sin_addr; 
    /* get mac address of the interface */ 
    if (ioctl(fd_arp, SIOCGIFHWADDR, &ifr) < 0) { 
        perror("ioctl SIOCGIFHWADDR error"); 
        exit(-1); 
    } 
    ptr = (u_char *)&ifr.ifr_ifru.ifru_hwaddr.sa_data[0]; 
    printf( "request mac %02x:%02x:%02x:%02x:%02x:%02x, ", 
            *ptr, *(ptr + 1), *(ptr + 2), *(ptr + 3), 
            *(ptr + 4), *(ptr + 5) ); 
    printf( "request netmask  %s ", inet_ntoa(mymask)); 
    printf( "request IP  %s\n", inet_ntoa(myself)); 
}  /* end of main */