ARP的C代码实现

linux下C语言实现ARP数据包发送

#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 
#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] \nusage : 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\n", 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\n", 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++;
                }
        }
}

ARP协议的c语言实现源代码

#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 
#define src_addr "192.168.0.239"
#define device  "eth0"
#define fill_buf "aaaaaaaaaaaa"
int socket_id;
char *target = src_addr;
int send_count = 0;
int recv_count = 0;
struct in_addr  src, dst;
struct sockaddr_ll   me,  he;
struct timeval   send_time, recv_time;
struct in_addr get_src_ip(char * devices)
{
struct sockaddr_in saddr;
int sock_id = socket(AF_INET, SOCK_DGRAM, 0);
if (sock_id < 0) {
  perror("socket");
  exit(2);
}
if (devices) {
      if (setsockopt(sock_id, SOL_SOCKET, SO_BINDTODEVICE, device, strlen(device)+1) == -1)
   perror("WARNING: interface is ignored");
}
int alen = sizeof(saddr);
memset(&saddr, 0, sizeof(saddr));
saddr.sin_port = htons(0x1000);
saddr.sin_family = AF_INET; 
if (connect(sock_id, (struct sockaddr*)&saddr, sizeof(saddr)) == -1) {
  perror("connect");
  exit(2);
}
if (getsockname(sock_id, (struct sockaddr*)&saddr, &alen) == -1) {
  perror("getsockname");
  exit(2);
}
close(sock_id);
return saddr.sin_addr;
}
int check_device(char* if_dev, int ss)
{
int ifindex;
struct ifreq ifr;
memset(&ifr, 0, sizeof(ifr));
strncpy(ifr.ifr_name, if_dev, IFNAMSIZ-1);
  if (ioctl(ss, SIOCGIFINDEX, &ifr) < 0) {
   fprintf(stderr, "arping: unknown iface %s\n", if_dev);
   exit(2);
  }
  ifindex = ifr.ifr_ifindex;
  if (ioctl(ss, SIOCGIFFLAGS, (char*)&ifr)) {
   perror("ioctl(SIOCGIFFLAGS)");
   exit(2);
  }
  if (!(ifr.ifr_flags&IFF_UP)) {
    printf("Interface \"%s\" is down\n", if_dev);
   exit(2);
  }
  if (ifr.ifr_flags&(IFF_NOARP|IFF_LOOPBACK)) {
    printf("Interface \"%s\" is not ARPable\n", if_dev);
   exit(2);
  }
return ifindex;
} // check_device()
int socket_init()
{
int s,  s_errno;
s = socket(PF_PACKET,  SOCK_DGRAM,  0);
s_errno = errno;
me.sll_family = AF_PACKET;
me.sll_ifindex = check_device(device,  s);
me.sll_protocol = htons(ETH_P_ARP);
if (bind(s,  (struct sockaddr*)&me,  sizeof(me)) == -1) {
  perror("bind");
  exit(2); 
}
int alen = sizeof(me);
if (getsockname(s, (struct sockaddr*)&me, &alen) == -1) {
  perror("getsockname");
  exit(2);
}
if (me.sll_halen == 0) {
  printf("Interface \"%s\" is not ARPable (no ll address)\n", device);
  exit(2);
}
he = me;
memset(he.sll_addr, -1, he.sll_halen);  // set dmac addr FF:FF:FF:FF:FF:FF
return s;
}
int
create_pkt(unsigned char * buf, struct in_addr src, struct in_addr dst, struct sockaddr_ll * FROM, struct sockaddr_ll * TO)
{
struct arphdr *ah = (struct arphdr*) buf;
unsigned char *p = (unsigned char *)(ah+1);
ah->ar_hrd = htons(FROM->sll_hatype);
if (ah->ar_hrd == htons(ARPHRD_FDDI))
  ah->ar_hrd = htons(ARPHRD_ETHER);
ah->ar_pro = htons(ETH_P_IP);
ah->ar_hln = FROM->sll_halen;
ah->ar_pln = 4;
ah->ar_op  =  htons(ARPOP_REQUEST);
memcpy(p, &FROM->sll_addr, ah->ar_hln);
p+=FROM->sll_halen;
memcpy(p, &src, 4);
p+=4;
memcpy(p, &TO->sll_addr, ah->ar_hln);
p+=ah->ar_hln;
memcpy(p, &dst, 4);
p+=4;
memcpy(p, fill_buf, strlen(fill_buf) );
p+=12;
return  (p-buf);
}
void send_pkt()
{
unsigned char send_buf[256];
int pkt_size = create_pkt(send_buf,  src,  dst,  &me,  &he);
gettimeofday(&send_time, NULL); 
int cc = sendto(socket_id, send_buf, pkt_size, 0, (struct sockaddr*)&he, sizeof(he));
if( cc == pkt_size )
  send_count++; 
alarm(1);
}
int chk_recv_pkt(unsigned char * buf, struct sockaddr_ll * FROM)
{
struct arphdr *ah = (struct arphdr*)buf;
unsigned char *p = (unsigned char *)(ah+1);
struct in_addr src_ip, dst_ip;
if (ah->ar_op != htons(ARPOP_REQUEST) &&  ah->ar_op != htons(ARPOP_REPLY))
  return 0;
if (ah->ar_pro != htons(ETH_P_IP) || ah->ar_pln != 4 || ah->ar_hln != me.sll_halen )
  return 0;
memcpy(&src_ip, p+ah->ar_hln, 4);
memcpy(&dst_ip, p+ah->ar_hln+4+ah->ar_hln, 4);
if (src_ip.s_addr != dst.s_addr || src.s_addr != dst_ip.s_addr )
  return 0;
return (p-buf);
}
void disp_info(int received,  struct in_addr dst, int msecs, int usecs, struct sockaddr_ll from)
{
printf("%03d ", received);
printf("%s ", from.sll_pkttype==PACKET_HOST ? "Unicast" : "Broadcast");
printf("%s from %s",  "reply",   inet_ntoa(dst) );
printf(" [%02X:%02X:%02X:%02X:%02X:%02X] ", from.sll_addr[0], from.sll_addr[1], \
  from.sll_addr[2], from.sll_addr[3], from.sll_addr[4], from.sll_addr[5]);   
printf(" %ld.%ld ms\n", (long int)msecs, (long int)usecs);
fflush(stdout);
}
void finish()
{
printf("\nSent %d ARP probe packet(s) \n", send_count);
printf("Received %d response(s)", recv_count);
printf("\n\n");
fflush(stdout);
exit(!recv_count);
}
////////////////////////////////////////////////////////////////
int
main(int argc, char **argv)
{
uid_t uid = getuid();
setuid(uid);
if( *(argv+1) != NULL )
  target = *(argv+1);
if (inet_aton(target, &dst) != 1) {
  struct hostent *hp;
  hp = gethostbyname2(target, AF_INET);
  printf("\ntarget = %s \n", target );
  if (!hp) {
   fprintf(stderr, "arping: unknown host %s\n", target);
   exit(2);
  }
  memcpy(&dst, hp->h_addr, 4);
}
src =  get_src_ip(device);
if (!src.s_addr ) {
  fprintf(stderr, "arping: no source address in not-DAD mode\n");
  exit(2);
}
socket_id = socket_init();
printf("\nARPING %s ", inet_ntoa(dst));
printf("from %s %s\n\n",  inet_ntoa(src), device ? : "");
signal(SIGINT,   finish);
signal(SIGALRM, send_pkt);
send_pkt();
while(1)
{
  struct sockaddr_ll from;
  int alen = sizeof(from);
  char recv_buf[0x1000];
 
  int recv_size = recvfrom(socket_id, recv_buf,  sizeof(recv_buf), 0,  (struct sockaddr *)&from, &alen );
 
  gettimeofday(&recv_time, NULL); 
  if( recv_size < 0 ) {
   perror("arping: recvfrom");
   continue;
  }
  if( chk_recv_pkt(recv_buf, &from) > 0 ) {
   memcpy(he.sll_addr, from.sll_addr, he.sll_halen);  
   long usecs, msecs;
   if (recv_time.tv_sec) {
    usecs = (recv_time.tv_sec - send_time.tv_sec) * 1000000 + recv_time.tv_usec - send_time.tv_usec;
    msecs = (usecs+500)/1000;
    usecs -= msecs*1000 - 500;
   }   
   recv_count++;
   disp_info(recv_count,  dst,  msecs,  usecs,  from);     
  } // if (chk...)   
 
}
return 0;
}

免费ARP简单介绍和程序编写

免费ARP，在网络上有很多的介绍。在《tcp/ip协议卷》中的第四章也有介绍，下面再啰嗦一下介绍其作用和操作：

免费ARP，主要用于检测网络中IP地址是否冲突，它是一种功能而非协议。当设备重启或代理ARP功能开启时就会向本地网络主动发免费ARP以检测IP地址是否冲突。免费ARP是以源、目的IP都是自己，源MAC也是自己，目标MAC是广播，即向自己所在网络请求自己的MAC地址，当网络中如果有其他主机使用了与自己相同的IP地址，他就会给主机一个ARP回复，此时如果发免费ARP的主机收到了回复就证明自己所用的IP地址有冲突，如果没有收到回复则说明没有IP地址冲突。

（若上面的文字有雷同，则以别人的文章为主；若有版权请告知我，本人会在24小时撤掉，谢谢~~~）

下面是免费ARP的代码，作为一个参考吧：

/////////////////////////////////////////////////////////////////////////////////
// 文件名： arp_func.c
// 作者：   cfjtaishan
// 版本：   1.0
// 日期：   2013-05-14
// 描述：   免费ARP--用于检测IP地址是否冲突.
// 历史记录：
/////////////////////////////////////////////////////////////////////////////////


#include
#include
#include
#include
#include
#include
#include
#include
#include
#include
#include
#include
#include
#include
#include

#define    FAILURE   -1
#define    SUCCESS    0

unsigned char src_ip[4] = { 192, 168, 9, 118 };    //要检测的主机IP地址
unsigned char src_mac[6] = {0x00, 0x0c, 0x29, 0x4b, 0x6c, 0x13};    //要检测的主机的MAC地址
unsigned char dst_ip[4] = { 192, 168, 9, 118 };    //目标IP地址
unsigned char dst_mac[6] = { 0xff, 0xff, 0xff, 0xff, 0xff, 0xff };    //ARP广播地址

int send_arp(int sockfd, struct sockaddr_ll *peer_addr);
int recv_arp(int sockfd, struct sockaddr_ll *peer_addr);

//ARP封装包
typedef struct _tagARP_PACKET{
    struct ether_header  eh;
    struct ether_arp arp;
}ARP_PACKET_OBJ, *ARP_PACKET_HANDLE;

int main(int argc, char *argv[])
{
    int sockfd;
    int rtval = -1;
    struct sockaddr_ll peer_addr;
    //创建socket
    sockfd = socket(AF_PACKET, SOCK_RAW, htons(ETH_P_ARP));
    if (sockfd < 0)
    {
        fprintf(stderr, "socket error: %s\n", strerror(errno));
        exit(EXIT_FAILURE);
    }

    memset(&peer_addr, 0, sizeof(peer_addr));
        peer_addr.sll_family = AF_PACKET;
        struct ifreq req;
    bzero(&req, sizeof(struct ifreq));
        strcpy(req.ifr_name, "eth0");
        if(ioctl(sockfd, SIOCGIFINDEX, &req) != 0)
        perror("ioctl()");
        peer_addr.sll_ifindex = req.ifr_ifindex;
        peer_addr.sll_protocol = htons(ETH_P_ARP);
    //peer_addr.sll_family = AF_PACKET;
    while (1)
    {
        rtval = send_arp(sockfd, &peer_addr);
        if (FAILURE == rtval)
        {
            fprintf(stderr, "Send arp socket failed: %s\n", strerror(errno));
        }
        rtval = recv_arp(sockfd, &peer_addr);
        if (rtval == SUCCESS)
        {
            printf ("Get packet from peer and IP conflicts!\n");
        }
        else if (rtval == FAILURE)
        {
            fprintf(stderr, "Recv arp IP not conflicts: %s\n", strerror(errno));
        }
        else
        {
            fprintf(stderr, "Recv arp socket failed: %s\n", strerror(errno));
        }
        //sleep(1);
    }
    return 0;
}
//////////////////////////////////////////////////////////////////////////
// 函数名: send_arp
// 描述 : 填充ARP数据包报文并发送出去。
// 参数:
//    [in] sockfd -- 创建的socket描述符;
//    [in] peer_addr -- 对端的IP信息
// 返回值:
//    成功: SUCCESS, 失败: FAILURE;
// 说明:
//////////////////////////////////////////////////////////////////////////
int send_arp(int sockfd, struct sockaddr_ll *peer_addr)
{
    int rtval;
    ARP_PACKET_OBJ frame;
    memset(&frame, 0x00, sizeof(ARP_PACKET_OBJ));

    //填充以太网头部
        memcpy(frame.eh.ether_dhost, dst_mac, 6);    //目的MAC地址
        memcpy(frame.eh.ether_shost, src_mac, 6);    //源MAC地址
        frame.eh.ether_type = htons(ETH_P_ARP);      //协议

    //填充ARP报文头部
        frame.arp.ea_hdr.ar_hrd = htons(ARPHRD_ETHER);    //硬件类型
        frame.arp.ea_hdr.ar_pro = htons(ETHERTYPE_IP);    //协议类型 ETHERTYPE_IP | ETH_P_IP
        frame.arp.ea_hdr.ar_hln = 6;                //硬件地址长度
        frame.arp.ea_hdr.ar_pln = 4;                //协议地址长度
        frame.arp.ea_hdr.ar_op = htons(ARPOP_REQUEST);    //ARP请求操作
        memcpy(frame.arp.arp_sha, src_mac, 6);    //源MAC地址
        memcpy(frame.arp.arp_spa, src_ip, 4);     //源IP地址
        memcpy(frame.arp.arp_tha, dst_mac, 6);    //目的MAC地址
        memcpy(frame.arp.arp_tpa, dst_ip, 4);     //目的IP地址

        rtval = sendto(sockfd, &frame, sizeof(ARP_PACKET_OBJ), 0,
        (struct sockaddr*)peer_addr, sizeof(struct sockaddr_ll));
    if (rtval < 0)
    {
        return FAILURE;
    }
    return SUCCESS;
}

//////////////////////////////////////////////////////////////////////////
// 函数名: recv_arp
// 描述 : 接收ARP回复数据报文并判断是不是对免费ARP的回复。
// 参数:
//    [in] sockfd -- 创建的socket描述符;
//    [in] peer_addr -- 对端的IP信息
// 返回值:
//    成功: SUCCESS, 失败: FAILURE;
// 说明:
//    若是对免费arp请求的回复则返回:SUCCESS.
//////////////////////////////////////////////////////////////////////////
int recv_arp(int sockfd, struct sockaddr_ll *peer_addr)
{
    int rtval;
    ARP_PACKET_OBJ frame;

    memset(&frame, 0, sizeof(ARP_PACKET_OBJ));
    rtval = recvfrom(sockfd, &frame, sizeof(frame), 0,
        NULL, NULL);
    //判断是否接收到数据并且是否为回应包
    if (htons(ARPOP_REPLY) == frame.arp.ea_hdr.ar_op && rtval > 0)
    {
        //判断源地址是否为冲突的IP地址
        if (memcmp(frame.arp.arp_spa, src_ip, 4) == 0)
        {
            fprintf(stdout, "IP address is common~\n");
            return SUCCESS;
        }
    }
    if (rtval < 0)
    {
        return FAILURE;
    }
    return FAILURE;
}

该程序可以测试局域网中的某个IP地址是否有冲突的，以便于确定该地址是否可以作为本机的IP地址。下面是通过wireshark抓到了免费的ARP数据包，以及回应包，如下：