C代碼實現Linux下模擬ping命令

fg360 9年前發布 | 9K 次閱讀 C/C++
/**

IP報頭格式數據結構定義在<netinet/ip.h>中    *
ICMP數據結構定義在<netinet/ip_icmp.h>中     *
套接字地址數據結構定義在<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，算術平均數差/
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;

}
/統計數據函數/
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）為單位累加
{
    sum += *w++;
    nleft -= 2;
}

if(nleft == 1)      //ICMP為奇數字節時，轉換最后一個字節，繼續累加
{
    *(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;   //發送的數據報編號
    icmp->icmp_id = pid;

packsize = 8 + datalen;     //數據報大小為64字節
tval = (struct timeval *)icmp->icmp_data;
gettimeofday(tval,NULL);        //記錄發送時間
//校驗算法
icmp->icmp_cksum =  cal_chksum((unsigned short *)icmp,packsize);    
return packsize;

}
/發送三個ICMP報文/
void send_packet()
{
    int packetsize;
    if(nsend < MAX_NO_PACKETS)
    {
        nsend++;
        packetsize = pack(nsend);   //設置ICMP報頭
        //發送數據報
        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)
    {

        //接收數據報
        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);       //剝去ICMP報頭
        nreceived++;
    }
}
/**剝去ICMP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報頭及數據報的總長度
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的ICMP的回應
if((icmp->icmp_type == ICMP_ECHOREPLY) && (icmp->icmp_id == pid))
{
    tvsend = (struct timeval *)icmp->icmp_data;
    tv_sub(&tvrecv,tvsend); //接收和發送的時間差
    //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/
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];
    //參數小于兩個
    if(argc < 2)

    {
        printf("usage:%s hostname/IP address\n",argv[0]);
        exit(1);
    }
    //不是ICMP協議
    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權限，設置當前權限
setuid(getuid());

/*擴大套接字的接收緩存區導50K，這樣做是為了減小接收緩存區溢出的
  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(網絡套接字)

//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);

//當按下ctrl+c時發出中斷信號，并開始執行統計函數
signal(SIGINT,statistics);  
while(nsend < MAX_NO_PACKETS){
    sleep(1);       //每隔一秒發送一個ICMP報文
    send_packet();      //發送ICMP報文
    recv_packet();      //接收ICMP報文
}
return 0;

}
</pre> 


 ping.c 

/**

IP報頭格式數據結構定義在<netinet/ip.h>中    *
ICMP數據結構定義在<netinet/ip_icmp.h>中     *
套接字地址數據結構定義在<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，算術平均數差/
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;

}
/統計數據函數/
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）為單位累加
{
    sum += *w++;
    nleft -= 2;
}

if(nleft == 1)      //ICMP為奇數字節時，轉換最后一個字節，繼續累加
{
    *(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;   //發送的數據報編號
    icmp->icmp_id = pid;

packsize = 8 + datalen;     //數據報大小為64字節
tval = (struct timeval *)icmp->icmp_data;
gettimeofday(tval,NULL);        //記錄發送時間
//校驗算法
icmp->icmp_cksum =  cal_chksum((unsigned short *)icmp,packsize);    
return packsize;

}
/發送三個ICMP報文/
void send_packet()
{
    int packetsize;
    if(nsend < MAX_NO_PACKETS)
    {
        nsend++;
        packetsize = pack(nsend);   //設置ICMP報頭
        //發送數據報
        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)
    {

        //接收數據報
        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);       //剝去ICMP報頭
        nreceived++;
    }
}
/**剝去ICMP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報頭及數據報的總長度
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的ICMP的回應
if((icmp->icmp_type == ICMP_ECHOREPLY) && (icmp->icmp_id == pid))
{
    tvsend = (struct timeval *)icmp->icmp_data;
    tv_sub(&tvrecv,tvsend); //接收和發送的時間差
    //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/
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];
    //參數小于兩個
    if(argc < 2)

    {
        printf("usage:%s hostname/IP address\n",argv[0]);
        exit(1);
    }
    //不是ICMP協議
    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權限，設置當前權限
setuid(getuid());

/*擴大套接字的接收緩存區導50K，這樣做是為了減小接收緩存區溢出的
  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(網絡套接字)

//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);

//當按下ctrl+c時發出中斷信號，并開始執行統計函數
signal(SIGINT,statistics);  
while(nsend < MAX_NO_PACKETS){
    sleep(1);       //每隔一秒發送一個ICMP報文
    send_packet();      //發送ICMP報文
    recv_packet();      //接收ICMP報文
}
return 0;

}</pre>
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