双机热备中解决IP漂移后arp表不更新

#include <iostream>
#include <sys/socket.h>
#include <sys/ioctl.h>
#include <netinet/if_ether.h>
#include <netinet/in.h>
#include <netinet/ip.h>
#include <netinet/udp.h>
#include <netinet/tcp.h>
#include <net/if.h>
#include <memory.h>
#include <arpa/inet.h>

using namespace std;
enum
{
ARP_MSG_SIZE = 0x2a
};

char * strncpy_IFNAMSIZ(char * dst, const char * src)
{
# ifndef IFNAMSIZ
enum
{
IFNAMSIZ = 16
};
# endif
return strncpy(dst, src, IFNAMSIZ);
}

struct arpMsg
{
/* Ethernet header */
uint8_t h_dest[6]; /* 00 destination ether addr */
uint8_t h_source[6]; /* 06 source ether addr */
uint16_t h_proto; /* 0c packet type ID field */

/* ARP packet */
uint16_t htype; /* 0e hardware type (must be ARPHRD_ETHER) */
uint16_t ptype; /* 10 protocol type (must be ETH_P_IP) */
uint8_t hlen; /* 12 hardware address length (must be 6) */
uint8_t plen; /* 13 protocol address length (must be 4) */
uint16_t operation; /* 14 ARP opcode */
uint8_t sHaddr[6]; /* 16 sender's hardware address */
uint8_t sInaddr[4]; /* 1c sender's IP address */
uint8_t tHaddr[6]; /* 20 target's hardware address */
uint8_t tInaddr[4]; /* 26 target's IP address */
uint8_t pad[18]; /* 2a pad for min. ethernet payload (60 bytes) */
} PACKED;
const int const_int_1 = 1;
int setsockopt_broadcast(int fd)
{
return setsockopt(fd, SOL_SOCKET, SO_BROADCAST, &const_int_1,
sizeof(const_int_1));
}

char * safe_strncpy(char * dst, const char * src, size_t size)
{
if (!size)
return dst;
dst[--size] = '/0';
return strncpy(dst, src, size);
}

int arpping(uint32_t test_ip, uint32_t from_ip, uint8_t * from_mac,
const char * interface)
{
int timeout_ms;
int s;
int rv = 1; /* "no reply received" yet */
struct sockaddr addr; /* for interface name */
struct arpMsg arp;

s = socket(PF_PACKET, SOCK_PACKET, htons(ETH_P_ARP));
if (s == -1)
{
perror("raw_socket");
return -1;
}

if (setsockopt_broadcast(s) == -1)
{
perror("cannot enable bcast on raw socket");
goto ret;
}

/* send arp request */
memset(&arp, 0, sizeof(arp));
memset(arp. h_dest, 0xff, 6); /* MAC DA */
memcpy(arp. h_source, from_mac, 6); /* MAC SA */
arp. h_proto = htons(ETH_P_ARP); /* protocol type (Ethernet) */
arp. htype = htons(ARPHRD_ETHER); /* hardware type */
arp. ptype = htons(ETH_P_IP); /* protocol type (ARP message) */
arp. hlen = 6; /* hardware address length */
arp. plen = 4; /* protocol address length */
arp. operation = htons(ARPOP_REQUEST); /* ARP op code */
memcpy(arp. sHaddr, from_mac, 6); /* source hardware address */
memcpy(arp. sInaddr, &from_ip, sizeof(from_ip)); /* source IP address */
/* tHaddr is zero-fiiled *//* target hardware address */
memcpy(arp. tInaddr, &test_ip, sizeof(test_ip)); /* target IP address */

memset(&addr, 0, sizeof(addr));
safe_strncpy(addr. sa_data, interface, sizeof(addr. sa_data));
if (sendto(s, &arp, sizeof(arp), 0, &addr, sizeof(addr)) < 0)
{
// TODO: error message? caller didn't expect us to fail,
// just returning 1 "no reply received" misleads it.
}

ret: close(s);
return rv;
}

int read_interface(const char * interface, int * ifindex, uint32_t * addr,
uint8_t * arp)
{
int fd;
struct ifreq ifr;
struct sockaddr_in * our_ip;

memset(&ifr, 0, sizeof(ifr));
fd = socket(AF_INET, SOCK_RAW, IPPROTO_RAW);

ifr. ifr_addr. sa_family = AF_INET;
strncpy_IFNAMSIZ(ifr. ifr_name, interface);
if (addr)
{
if (ioctl(fd, SIOCGIFADDR, &ifr) != 0)
{
perror("ioctl");
close(fd);
return -1;
}
our_ip = (struct sockaddr_in *) &ifr. ifr_addr;
*addr = our_ip-> sin_addr. s_addr;
printf("ip of %s = %s \n", interface, inet_ntoa(our_ip-> sin_addr));
}

if (ifindex)
{
if (ioctl(fd, SIOCGIFINDEX, &ifr) != 0)
{
close(fd);
return -1;
}
printf("adapter index %d", ifr. ifr_ifindex);
*ifindex = ifr. ifr_ifindex;
}

if (arp)
{
if (ioctl(fd, SIOCGIFHWADDR, &ifr) != 0)
{
close(fd);
return -1;
}
memcpy(arp, ifr. ifr_hwaddr. sa_data, 6);
printf("adapter hardware address %02x:%02x:%02x:%02x:%02x:%02x\n",
arp[0], arp[1], arp[2], arp[3], arp[4], arp[5]);
}
close(fd);
return 0;
}

int main(void)
{
uint32_t TEST_IP = inet_addr("10.192.64.255");
char interface[] = "eth0";
uint32_t ip, t_ip;
uint8_t mac[6];
read_interface(interface, NULL, &ip, mac);
char buf[128];
strcpy(buf, "ifconfig eth0:1 10.192.64.137 netmask 255.255.255.0");
system(buf);

t_ip = inet_addr("10.192.64.137");
for (int i = 0; i < 10; i++)
{
arpping(TEST_IP, t_ip, mac, interface);
usleep(50);
}
return 0;

}