linux下C語言實現ARP數據包發送

可以隨意發送ARP數據包，源碼如下：
#include <netdb.h>
#include <sys/socket.h>
#include <sys/types.h>
#include <stdio.h>
#include <errno.h>
#include <sys/ioctl.h>
#include <net/if.h>
#include <signal.h>
#include <netinet/ip.h>
#include <netinet/in.h>
#include <string.h>
#include <arpa/inet.h>
#include <netinet/ip_icmp.h>
#include <linux/if_ether.h>
#define ETH_HW_ADDR_LEN 6
#define IP_ADDR_LEN 4
#define ARP_FRAME_TYPE 0x0806
#define ETHER_HW_TYPE 1
#define IP_PROTO_TYPE 0x0800
#define OP_ARP_REQUEST 2
#define OP_ARP_QUEST 1
#define DEFAULT_DEVICE "eth0"

char usage[] =
{"send_arp: sends out custom ARP packet. [email protected] usage : send_arp src_ip_addr src_hw_addr targ_ip_addr tar_hw_addr number"};

struct arp_packet
{
u_char targ_hw_addr[ETH_HW_ADDR_LEN];
u_char src_hw_addr[ETH_HW_ADDR_LEN];
u_short frame_type;
u_short hw_type;
u_short prot_type;
u_char hw_addr_size;
u_char prot_addr_size;
u_short op;
u_char sndr_hw_addr[ETH_HW_ADDR_LEN];
u_char sndr_ip_addr[IP_ADDR_LEN];
u_char rcpt_hw_addr[ETH_HW_ADDR_LEN];
u_char rcpt_ip_addr[IP_ADDR_LEN];
u_char padding[18];
};

void die(char*);
void get_ip_addr(struct in_addr*, char*);
void get_hw_addr(char*, char*);

int main(int argc, char* argv[])
{
struct in_addr src_in_addr, targ_in_addr;
struct arp_packet pkt;
struct sockaddr sa;
int sock;
int j, number;
if (argc != 6)
{
die(usage);
}
sock = socket(AF_INET, SOCK_PACKET, htons(ETH_P_RARP));
if (sock < 0)
{
perror("socket");
exit(1);
}
number = atoi(argv[5]);
pkt.frame_type = htons(ARP_FRAME_TYPE);
pkt.hw_type = htons(ETHER_HW_TYPE);
pkt.prot_type = htons(IP_PROTO_TYPE);
pkt.hw_addr_size = ETH_HW_ADDR_LEN;
pkt.prot_addr_size = IP_ADDR_LEN;
pkt.op = htons(OP_ARP_QUEST);
get_hw_addr(pkt.targ_hw_addr, argv[4]);
get_hw_addr(pkt.rcpt_hw_addr, argv[4]);
get_hw_addr(pkt.src_hw_addr, argv[2]);
get_hw_addr(pkt.sndr_hw_addr, argv[2]);
get_ip_addr(&src_in_addr, argv[1]);
get_ip_addr(&targ_in_addr, argv[3]);
memcpy(pkt.sndr_ip_addr, &src_in_addr, IP_ADDR_LEN);
memcpy(pkt.rcpt_ip_addr, &targ_in_addr, IP_ADDR_LEN);
bzero(pkt.padding, 18);
strcpy(sa.sa_data, DEFAULT_DEVICE);
for (j = 0; j < number; j++)
{
if (sendto(sock, &pkt, sizeof(pkt), 0, &sa, sizeof(sa)) < 0)
{
perror("sendto");
exit(1);
}
}
exit(0);
}

void die(char* str)
{
fprintf(stderr, "%s ", str);
exit(1);
}

void get_ip_addr(struct in_addr* in_addr, char* str)
{
struct hostent* hostp;
in_addr->s_addr = inet_addr(str);
if (in_addr->s_addr == -1)
{
if ((hostp = gethostbyname(str)))
{
bcopy(hostp->h_addr, in_addr, hostp->h_length);
}
else
{
fprintf(stderr, "send_arp: unknown host %s ", str);
exit(1);
}
}
}

void get_hw_addr(char* buf, char* str)
{
int i;
char c, val;
for (i = 0; i < ETH_HW_ADDR_LEN; i++)
{
if (!(c = tolower(*str++)))
{
die("Invalid hardware address");
}
if (isdigit(c))
{
val = c - 0;
}
else if (c >= a && c <= f)
{
val = c - a + 10;
}
else
{
die("Invalid hardware address");
}
*buf = val << 4;
if (!(c = tolower(*str++)))
{
die("Invalid hardware address");
}
if (isdigit(c))
{
val = c - 0;
}
else if (c >= a && c <= f)
{
val = c - a + 10;
}
else
{
die("Invalid hardware address");
}
*buf++ |= val;
if (*str == :)
{
str++;
}
}
}