C代碼實現(xiàn)Linux下模擬ping命令
2018-07-20 來源：open-open
/********************************************************
* IP報頭格式數(shù)據(jù)結(jié)構(gòu)定義在<netinet/ip.h>中 *
* ICMP數(shù)據(jù)結(jié)構(gòu)定義在<netinet/ip_icmp.h>中 *
* 套接字地址數(shù)據(jù)結(jié)構(gòu)定義在<netinet/in.h>中 *
********************************************************/
#include <stdio.h>
#include <stdlib.h>
#include <signal.h>
#include <arpa/inet.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <unistd.h>
#include <netinet/in.h>
#include <netinet/ip.h>
#include <netinet/ip_icmp.h>
#include <netdb.h>
#include <setjmp.h>
#include <errno.h>
#define PACKET_SIZE 4096
#define MAX_WAIT_TIME 5
#define MAX_NO_PACKETS 10000
char *addr[];
char sendpacket[PACKET_SIZE];
char recvpacket[PACKET_SIZE];
int sockfd,datalen = 56;
int nsend = 0, nreceived = 0;
double temp_rtt[MAX_NO_PACKETS];
double all_time = 0;
double min = 0;
double max = 0;
double avg = 0;
double mdev = 0;
struct sockaddr_in dest_addr;
struct sockaddr_in from;
struct timeval tvrecv;
pid_t pid;
void statistics(int sig);
void send_packet(void);
void recv_packet(void);
void computer_rtt(void);
void tv_sub(struct timeval *out,struct timeval *in);
int pack(int pack_no);
int unpack(char *buf,int len);
unsigned short cal_checksum(unsigned short *addr,int len);
/*計算rtt最小、大值，平均值，算術(shù)平均數(shù)差*/
void computer_rtt()
{
double sum_avg = 0;
int i;
min = max = temp_rtt[0];
avg = all_time/nreceived;
for(i=0; i<nreceived; i++){
if(temp_rtt[i] < min)
min = temp_rtt[i];
else if(temp_rtt[i] > max)
max = temp_rtt[i];
if((temp_rtt[i]-avg) < 0)
sum_avg += avg - temp_rtt[i];
else
sum_avg += temp_rtt[i] - avg;
}
mdev = sum_avg/nreceived;
}
/****統(tǒng)計數(shù)據(jù)函數(shù)****/
void statistics(int sig)
{
computer_rtt(); //計算rtt
printf("\n------ %s ping statistics ------\n",addr[0]);
printf("%d packets transmitted,%d received,%d%% packet loss,time %.f ms\n",
nsend,nreceived,(nsend-nreceived)/nsend*100,all_time);
printf("rtt min/avg/max/mdev = %.3f/%.3f/%.3f/%.3f ms\n",
min,avg,max,mdev);
close(sockfd);
exit(1);
}
/****檢驗和算法****/
unsigned short cal_chksum(unsigned short *addr,int len)
{
int nleft = len;
int sum = 0;
unsigned short *w = addr;
unsigned short check_sum = 0;
while(nleft>1) //ICMP包頭以字（2字節(jié)）為單位累加
{
sum += *w++;
nleft -= 2;
}
if(nleft == 1) //ICMP為奇數(shù)字節(jié)時，轉(zhuǎn)換最后一個字節(jié)，繼續(xù)累加
{
*(unsigned char *)(&check_sum) = *(unsigned char *)w;
sum += check_sum;
}
sum = (sum >> 16) + (sum & 0xFFFF);
sum += (sum >> 16);
check_sum = ~sum; //取反得到校驗和
return check_sum;
}
/*設(shè)置ICMP報頭*/
int pack(int pack_no)
{
int i,packsize;
struct icmp *icmp;
struct timeval *tval;
icmp = (struct icmp*)sendpacket;
icmp->icmp_type = ICMP_ECHO; //ICMP_ECHO類型的類型號為0
icmp->icmp_code = 0;
icmp->icmp_cksum = 0;
icmp->icmp_seq = pack_no; //發(fā)送的數(shù)據(jù)報編號
icmp->icmp_id = pid;
packsize = 8 + datalen; //數(shù)據(jù)報大小為64字節(jié)
tval = (struct timeval *)icmp->icmp_data;
gettimeofday(tval,NULL); //記錄發(fā)送時間
//校驗算法
icmp->icmp_cksum = cal_chksum((unsigned short *)icmp,packsize);
return packsize;
}
/****發(fā)送三個ICMP報文****/
void send_packet()
{
int packetsize;
if(nsend < MAX_NO_PACKETS)
{
nsend++;
packetsize = pack(nsend); //設(shè)置ICMP報頭
//發(fā)送數(shù)據(jù)報
if(sendto(sockfd,sendpacket,packetsize,0,
(struct sockaddr *)&dest_addr,sizeof(dest_addr)) < 0)
{
perror("sendto error");
}
}
}
/****接受所有ICMP報文****/
void recv_packet()
{
int n,fromlen;
extern int error;
fromlen = sizeof(from);
if(nreceived < nsend)
{
//接收數(shù)據(jù)報
if((n = recvfrom(sockfd,recvpacket,sizeof(recvpacket),0,
(struct sockaddr *)&from,&fromlen)) < 0)
{
perror("recvfrom error");
}
gettimeofday(&tvrecv,NULL); //記錄接收時間
unpack(recvpacket,n); //剝?nèi)CMP報頭
nreceived++;
}
}
/******剝?nèi)CMP報頭******/
int unpack(char *buf,int len)
{
int i;
int iphdrlen; //ip頭長度
struct ip *ip;
struct icmp *icmp;
struct timeval *tvsend;
double rtt;
ip = (struct ip *)buf;
iphdrlen = ip->ip_hl << 2; //求IP報文頭長度，即IP報頭長度乘4
icmp = (struct icmp *)(buf + iphdrlen); //越過IP頭，指向ICMP報頭
len -= iphdrlen; //ICMP報頭及數(shù)據(jù)報的總長度
if(len < 8) //小于ICMP報頭的長度則不合理
{
printf("ICMP packet\'s length is less than 8\n");
return -1;
}
//確保所接收的是所發(fā)的ICMP的回應(yīng)
if((icmp->icmp_type == ICMP_ECHOREPLY) && (icmp->icmp_id == pid))
{
tvsend = (struct timeval *)icmp->icmp_data;
tv_sub(&tvrecv,tvsend); //接收和發(fā)送的時間差
//以毫秒為單位計算rtt
rtt = tvrecv.tv_sec*1000 + tvrecv.tv_usec/1000;
temp_rtt[nreceived] = rtt;
all_time += rtt; //總時間
//顯示相關(guān)的信息
printf("%d bytes from %s: icmp_seq=%u ttl=%d time=%.1f ms\n",
len,inet_ntoa(from.sin_addr),
icmp->icmp_seq,ip->ip_ttl,rtt);
}
else return -1;
}
//兩個timeval相減
void tv_sub(struct timeval *recvtime,struct timeval *sendtime)
{
long sec = recvtime->tv_sec - sendtime->tv_sec;
long usec = recvtime->tv_usec - sendtime->tv_usec;
if(usec >= 0){
recvtime->tv_sec = sec;
recvtime->tv_usec = usec;
}else{
recvtime->tv_sec = sec - 1;
recvtime->tv_usec = -usec;
}
}
/*主函數(shù)*/
main(int argc,char *argv[])
{
struct hostent *host;
struct protoent *protocol;
unsigned long inaddr = 0;
// int waittime = MAX_WAIT_TIME;
int size = 50 * 1024;
addr[0] = argv[1];
//參數(shù)小于兩個
if(argc < 2)
{
printf("usage:%s hostname/IP address\n",argv[0]);
exit(1);
}
//不是ICMP協(xié)議
if((protocol = getprotobyname("icmp")) == NULL)
{
perror("getprotobyname");
exit(1);
}
//生成使用ICMP的原始套接字，只有root才能生成
if((sockfd = socket(AF_INET,SOCK_RAW,protocol->p_proto)) < 0)
{
perror("socket error");
exit(1);
}
//回收root權(quán)限，設(shè)置當(dāng)前權(quán)限
setuid(getuid());
/*擴大套接字的接收緩存區(qū)導(dǎo)50K，這樣做是為了減小接收緩存區(qū)溢出的
可能性，若無意中ping一個廣播地址或多播地址，將會引來大量的應(yīng)答*/
setsockopt(sockfd,SOL_SOCKET,SO_RCVBUF,&size,sizeof(size));
bzero(&dest_addr,sizeof(dest_addr)); //初始化
dest_addr.sin_family = AF_INET; //套接字域是AF_INET(網(wǎng)絡(luò)套接字)
//判斷主機名是否是IP地址
if(inet_addr(argv[1]) == INADDR_NONE)
{
if((host = gethostbyname(argv[1])) == NULL) //是主機名
{
perror("gethostbyname error");
exit(1);
}
memcpy((char *)&dest_addr.sin_addr,host->h_addr,host->h_length);
}
else{ //是IP 地址
dest_addr.sin_addr.s_addr = inet_addr(argv[1]);
}
pid = getpid();
printf("PING %s(%s):%d bytes of data.\n",argv[1],
inet_ntoa(dest_addr.sin_addr),datalen);
//當(dāng)按下ctrl+c時發(fā)出中斷信號，并開始執(zhí)行統(tǒng)計函數(shù)
signal(SIGINT,statistics);
while(nsend < MAX_NO_PACKETS){
sleep(1); //每隔一秒發(fā)送一個ICMP報文
send_packet(); //發(fā)送ICMP報文
recv_packet(); //接收ICMP報文
}
return 0;
}
ping.c
/********************************************************
* IP報頭格式數(shù)據(jù)結(jié)構(gòu)定義在<netinet/ip.h>中 *
* ICMP數(shù)據(jù)結(jié)構(gòu)定義在<netinet/ip_icmp.h>中 *
* 套接字地址數(shù)據(jù)結(jié)構(gòu)定義在<netinet/in.h>中 *
********************************************************/
#include <stdio.h>
#include <stdlib.h>
#include <signal.h>
#include <arpa/inet.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <unistd.h>
#include <netinet/in.h>
#include <netinet/ip.h>
#include <netinet/ip_icmp.h>
#include <netdb.h>
#include <setjmp.h>
#include <errno.h>
#define PACKET_SIZE 4096
#define MAX_WAIT_TIME 5
#define MAX_NO_PACKETS 10000
char *addr[];
char sendpacket[PACKET_SIZE];
char recvpacket[PACKET_SIZE];
int sockfd,datalen = 56;
int nsend = 0, nreceived = 0;
double temp_rtt[MAX_NO_PACKETS];
double all_time = 0;
double min = 0;
double max = 0;
double avg = 0;
double mdev = 0;
struct sockaddr_in dest_addr;
struct sockaddr_in from;
struct timeval tvrecv;
pid_t pid;
void statistics(int sig);
void send_packet(void);
void recv_packet(void);
void computer_rtt(void);
void tv_sub(struct timeval *out,struct timeval *in);
int pack(int pack_no);
int unpack(char *buf,int len);
unsigned short cal_checksum(unsigned short *addr,int len);
/*計算rtt最小、大值，平均值，算術(shù)平均數(shù)差*/
void computer_rtt()
{
double sum_avg = 0;
int i;
min = max = temp_rtt[0];
avg = all_time/nreceived;
for(i=0; i<nreceived; i++){
if(temp_rtt[i] < min)
min = temp_rtt[i];
else if(temp_rtt[i] > max)
max = temp_rtt[i];
if((temp_rtt[i]-avg) < 0)
sum_avg += avg - temp_rtt[i];
else
sum_avg += temp_rtt[i] - avg;
}
mdev = sum_avg/nreceived;
}
/****統(tǒng)計數(shù)據(jù)函數(shù)****/
void statistics(int sig)
{
computer_rtt(); //計算rtt
printf("\n------ %s ping statistics ------\n",addr[0]);
printf("%d packets transmitted,%d received,%d%% packet loss,time %.f ms\n",
nsend,nreceived,(nsend-nreceived)/nsend*100,all_time);
printf("rtt min/avg/max/mdev = %.3f/%.3f/%.3f/%.3f ms\n",
min,avg,max,mdev);
close(sockfd);
exit(1);
}
/****檢驗和算法****/
unsigned short cal_chksum(unsigned short *addr,int len)
{
int nleft = len;
int sum = 0;
unsigned short *w = addr;
unsigned short check_sum = 0;
while(nleft>1) //ICMP包頭以字（2字節(jié)）為單位累加
{
sum += *w++;
nleft -= 2;
}
if(nleft == 1) //ICMP為奇數(shù)字節(jié)時，轉(zhuǎn)換最后一個字節(jié)，繼續(xù)累加
{
*(unsigned char *)(&check_sum) = *(unsigned char *)w;
sum += check_sum;
}
sum = (sum >> 16) + (sum & 0xFFFF);
sum += (sum >> 16);
check_sum = ~sum; //取反得到校驗和
return check_sum;
}
/*設(shè)置ICMP報頭*/
int pack(int pack_no)
{
int i,packsize;
struct icmp *icmp;
struct timeval *tval;
icmp = (struct icmp*)sendpacket;
icmp->icmp_type = ICMP_ECHO; //ICMP_ECHO類型的類型號為0
icmp->icmp_code = 0;
icmp->icmp_cksum = 0;
icmp->icmp_seq = pack_no; //發(fā)送的數(shù)據(jù)報編號
icmp->icmp_id = pid;
packsize = 8 + datalen; //數(shù)據(jù)報大小為64字節(jié)
tval = (struct timeval *)icmp->icmp_data;
gettimeofday(tval,NULL); //記錄發(fā)送時間
//校驗算法
icmp->icmp_cksum = cal_chksum((unsigned short *)icmp,packsize);
return packsize;
}
/****發(fā)送三個ICMP報文****/
void send_packet()
{
int packetsize;
if(nsend < MAX_NO_PACKETS)
{
nsend++;
packetsize = pack(nsend); //設(shè)置ICMP報頭
//發(fā)送數(shù)據(jù)報
if(sendto(sockfd,sendpacket,packetsize,0,
(struct sockaddr *)&dest_addr,sizeof(dest_addr)) < 0)
{
perror("sendto error");
}
}
}
/****接受所有ICMP報文****/
void recv_packet()
{
int n,fromlen;
extern int error;
fromlen = sizeof(from);
if(nreceived < nsend)
{
//接收數(shù)據(jù)報
if((n = recvfrom(sockfd,recvpacket,sizeof(recvpacket),0,
(struct sockaddr *)&from,&fromlen)) < 0)
{
perror("recvfrom error");
}
gettimeofday(&tvrecv,NULL); //記錄接收時間
unpack(recvpacket,n); //剝?nèi)CMP報頭
nreceived++;
}
}
/******剝?nèi)CMP報頭******/
int unpack(char *buf,int len)
{
int i;
int iphdrlen; //ip頭長度
struct ip *ip;
struct icmp *icmp;
struct timeval *tvsend;
double rtt;
ip = (struct ip *)buf;
iphdrlen = ip->ip_hl << 2; //求IP報文頭長度，即IP報頭長度乘4
icmp = (struct icmp *)(buf + iphdrlen); //越過IP頭，指向ICMP報頭
len -= iphdrlen; //ICMP報頭及數(shù)據(jù)報的總長度
if(len < 8) //小于ICMP報頭的長度則不合理
{
printf("ICMP packet\'s length is less than 8\n");
return -1;
}
//確保所接收的是所發(fā)的ICMP的回應(yīng)
if((icmp->icmp_type == ICMP_ECHOREPLY) && (icmp->icmp_id == pid))
{
tvsend = (struct timeval *)icmp->icmp_data;
tv_sub(&tvrecv,tvsend); //接收和發(fā)送的時間差
//以毫秒為單位計算rtt
rtt = tvrecv.tv_sec*1000 + tvrecv.tv_usec/1000;
temp_rtt[nreceived] = rtt;
all_time += rtt; //總時間
//顯示相關(guān)的信息
printf("%d bytes from %s: icmp_seq=%u ttl=%d time=%.1f ms\n",
len,inet_ntoa(from.sin_addr),
icmp->icmp_seq,ip->ip_ttl,rtt);
}
else return -1;
}
//兩個timeval相減
void tv_sub(struct timeval *recvtime,struct timeval *sendtime)
{
long sec = recvtime->tv_sec - sendtime->tv_sec;
long usec = recvtime->tv_usec - sendtime->tv_usec;
if(usec >= 0){
recvtime->tv_sec = sec;
recvtime->tv_usec = usec;
}else{
recvtime->tv_sec = sec - 1;
recvtime->tv_usec = -usec;
}
}
/*主函數(shù)*/
main(int argc,char *argv[])
{
struct hostent *host;
struct protoent *protocol;
unsigned long inaddr = 0;
// int waittime = MAX_WAIT_TIME;
int size = 50 * 1024;
addr[0] = argv[1];
//參數(shù)小于兩個
if(argc < 2)
{
printf("usage:%s hostname/IP address\n",argv[0]);
exit(1);
}
//不是ICMP協(xié)議
if((protocol = getprotobyname("icmp")) == NULL)
{
perror("getprotobyname");
exit(1);
}
//生成使用ICMP的原始套接字，只有root才能生成
if((sockfd = socket(AF_INET,SOCK_RAW,protocol->p_proto)) < 0)
{
perror("socket error");
exit(1);
}
//回收root權(quán)限，設(shè)置當(dāng)前權(quán)限
setuid(getuid());
/*擴大套接字的接收緩存區(qū)導(dǎo)50K，這樣做是為了減小接收緩存區(qū)溢出的
可能性，若無意中ping一個廣播地址或多播地址，將會引來大量的應(yīng)答*/
setsockopt(sockfd,SOL_SOCKET,SO_RCVBUF,&size,sizeof(size));
bzero(&dest_addr,sizeof(dest_addr)); //初始化
dest_addr.sin_family = AF_INET; //套接字域是AF_INET(網(wǎng)絡(luò)套接字)
//判斷主機名是否是IP地址
if(inet_addr(argv[1]) == INADDR_NONE)
{
if((host = gethostbyname(argv[1])) == NULL) //是主機名
{
perror("gethostbyname error");
exit(1);
}
memcpy((char *)&dest_addr.sin_addr,host->h_addr,host->h_length);
}
else{ //是IP 地址
dest_addr.sin_addr.s_addr = inet_addr(argv[1]);
}
pid = getpid();
printf("PING %s(%s):%d bytes of data.\n",argv[1],
inet_ntoa(dest_addr.sin_addr),datalen);
//當(dāng)按下ctrl+c時發(fā)出中斷信號，并開始執(zhí)行統(tǒng)計函數(shù)
signal(SIGINT,statistics);
while(nsend < MAX_NO_PACKETS){
sleep(1); //每隔一秒發(fā)送一個ICMP報文
send_packet(); //發(fā)送ICMP報文
recv_packet(); //接收ICMP報文
}
return 0;
}
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