linux下使用原始套接字實現ping的功能:
下面是在網上 抄的,
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <errno.h>
#include <sys/socket.h>
#include <sys/types.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <netdb.h>
#include <sys/time.h>
#include <netinet/ip_icmp.h>
#include <unistd.h>
#include <signal.h>
#define MAX_SIZE 1024
char send_buf[MAX_SIZE];
char recv_buf[MAX_SIZE];
int nsend = 0,nrecv = 0;
int datalen = 56;
//統計結果
void statistics(int signum)
{
printf("\n----------------PING statistics---------------\n");
printf("%d packets transmitted,%d recevid,%%%d lost\n",nsend,nrecv,(nsend - nrecv)/nsend * 100);
exit(EXIT_SUCCESS);
}
//校驗和算法
int calc_chsum(unsigned short *addr,int len)
{
int sum = 0,n = len;
unsigned short answer = 0;
unsigned short *p = addr;
//每兩個字節相加
while(n > 1)
{
sum += *p ++;
n -= 2;
}
//處理數據大小是奇數,在最後一個字節後面補0
if(n == 1)
{
*((unsigned char *)&answer) = *(unsigned char *)p;
sum += answer;
}
//將得到的sum值的高2字節和低2字節相加
sum = (sum >> 16) + (sum & 0xffff);
//處理溢出的情況
sum += sum >> 16;
answer = ~sum;
return answer;
}
int pack(int pack_num)
{
int packsize;
struct icmp *icmp;
struct timeval *tv;
icmp = (struct icmp *)send_buf;
icmp->icmp_type = ICMP_ECHO;
icmp->icmp_code = 0;
icmp->icmp_cksum = 0;
icmp->icmp_id = htons(getpid());
icmp->icmp_seq = htons(pack_num);
tv = (struct timeval *)icmp->icmp_data;
//記錄發送時間
if(gettimeofday(tv,NULL) < 0)
{
perror("Fail to gettimeofday");
return -1;
}
packsize = 8 + datalen;
icmp->icmp_cksum = calc_chsum((unsigned short *)icmp,packsize);
return packsize;
}
int send_packet(int sockfd,struct sockaddr *paddr)
{
int packsize;
//將send_buf填上a
memset(send_buf,'a',sizeof(send_buf));
nsend ++;
//打icmp包
packsize = pack(nsend);
if(sendto(sockfd,send_buf,packsize,0,paddr,sizeof(struct sockaddr)) < 0)
{
perror("Fail to sendto");
return -1;
}
return 0;
}
struct timeval time_sub(struct timeval *tv_send,struct timeval *tv_recv)
{
struct timeval ts;
if(tv_recv->tv_usec - tv_send->tv_usec < 0)
{
tv_recv->tv_sec --;
tv_recv->tv_usec += 1000000;
}
ts.tv_sec = tv_recv->tv_sec - tv_send->tv_sec;
ts.tv_usec = tv_recv->tv_usec - tv_send->tv_usec;
return ts;
}
int unpack(int len,struct timeval *tv_recv,struct sockaddr *paddr,char *ipname)
{
struct ip *ip;
struct icmp *icmp;
struct timeval *tv_send,ts;
int ip_head_len;
float rtt;
ip = (struct ip *)recv_buf;
ip_head_len = ip->ip_hl << 2;
icmp = (struct icmp *)(recv_buf + ip_head_len);
len -= ip_head_len;
if(len < 8)
{
printf("ICMP packets\'s is less than 8.\n");
return -1;
}
if(ntohs(icmp->icmp_id) == getpid() && icmp->icmp_type == ICMP_ECHOREPLY)
{
nrecv ++;
tv_send = (struct timeval *)icmp->icmp_data;
ts = time_sub(tv_send,tv_recv);
rtt = ts.tv_sec * 1000 + (float)ts.tv_usec/1000;//以毫秒爲單位
printf("%d bytes from %s (%s):icmp_req = %d ttl=%d time=%.3fms.\n",
len,ipname,inet_ntoa(((struct sockaddr_in *)paddr)->sin_addr),ntohs(icmp->icmp_seq),ip->ip_ttl,rtt);
}
return 0;
}
int recv_packet(int sockfd,char *ipname)
{
int addr_len ,n;
struct timeval tv;
struct sockaddr from_addr;
addr_len = sizeof(struct sockaddr);
if((n = recvfrom(sockfd,recv_buf,sizeof(recv_buf),0,&from_addr,&addr_len)) < 0)
{
perror("Fail to recvfrom");
return -1;
}
if(gettimeofday(&tv,NULL) < 0)
{
perror("Fail to gettimeofday");
return -1;
}
unpack(n,&tv,&from_addr,ipname);
return 0;
}
int main(int argc,char *argv[])
{
int size = 50 * 1024;
int sockfd,netaddr;
struct protoent *protocol;
struct hostent *host;
struct sockaddr_in peer_addr;
if(argc < 2)
{
fprintf(stderr,"usage : %s ip.\n",argv[0]);
exit(EXIT_FAILURE);
}
//獲取icmp的信息
if((protocol = getprotobyname("icmp")) == NULL)
{
perror("Fail to getprotobyname");
exit(EXIT_FAILURE);
}
//創建原始套接字
if((sockfd = socket(AF_INET,SOCK_RAW,protocol->p_proto)) < 0)
{
perror("Fail to socket");
exit(EXIT_FAILURE);
}
//回收root權限,設置當前用戶權限
setuid(getuid());
/*
擴大套接子接收緩衝區到50k,這樣做主要爲了減少接收緩衝區溢出的可能性
若無影中ping一個廣播地址或多播地址,將會引來大量應答
*/
if(setsockopt(sockfd,SOL_SOCKET,SO_RCVBUF,&size,sizeof(size)) < 0)
{
perror("Fail to setsockopt");
exit(EXIT_FAILURE);
}
//填充對方的地址
bzero(&peer_addr,sizeof(peer_addr));
peer_addr.sin_family = AF_INET;
//判斷是主機名(域名)還是ip
if((netaddr = inet_addr(argv[1])) == INADDR_NONE)
{
//是主機名(域名)
if((host = gethostbyname(argv[1])) == NULL)
{
fprintf(stderr,"%s unknown host : %s.\n",argv[0],argv[1]);
exit(EXIT_FAILURE);
}
memcpy((char *)&peer_addr.sin_addr,host->h_addr,host->h_length);
}else{//ip地址
peer_addr.sin_addr.s_addr = netaddr;
}
//註冊信號處理函數
signal(SIGALRM,statistics);
signal(SIGINT,statistics);
alarm(5);
//開始信息
printf("PING %s(%s) %d bytes of data.\n",argv[1],inet_ntoa(peer_addr.sin_addr),datalen);
//發送包文和接收報文
while(1)
{
send_packet(sockfd,(struct sockaddr *)&peer_addr);
recv_packet(sockfd,argv[1]);
alarm(5);
sleep(1);
}
exit(EXIT_SUCCESS);
}