icmp的程序(ping的实现)
2013-09-29 15:55
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code来源于《网络编程与分层协议设计》 chap7 ICMP协议程序设计
----没有理解,没有编译,只是敲了出来
ping.h
#define ICMP_ECHOREPLY 0
#define ICMP_ECHO 8
#define BUFSIZE 1500
#define DEFAULT_LEN 56
typedef unsigned char u8;
typedef unsigned short u16;
typedef unsigned int u32;
struct icmphdr{
u8 type;
u8 code;
u16 checksum;
union{
struct {
u16 id;
u16 sequence;
}echo;
u32 gateway;
struct
{
u16 unused;
u16 mtu;
}frag;
}un;
u8 data[0];
#define icmp_id un.echo.id
#define icmp_seq un.echo.sequence
};
#define ICMP_HSIZE sizeof(struct icmphdr)
struct iphdr{
u8 hlen:4, ver:4;
u8 tos;
u16 tot_len;
u16 id;
u16 frag_off;
u8 ttl;
u8 protocol;
u16 check;
u32 saddr;
u32 daddr;
};
char *hostname;
int datalen = DEFAULT_LEN;
char sendbuf[BUFSIZE];
char recvbuf[BUFSIZE];
int nsent;
int nrecv;
pid_t pid;
struct timeval recvtime;
int sockfd;
struct sockaddr_in dest;
struct sockaddr_in from;
struct sigaction act_alarm;
struct sigaction act_int;
void alarm_handler(int);
void int_handler(int);
void set_sighandler();
void send_ping();
void recv_reply();
u16 checksum(u8 *buf, int len);
int handle_pkt();
void get_statistics(int, int);
void bail(const char *)
ping.c
#include <stdio.h>
#include <stdlib.h>
#include <sys/time.h>
#include <unistd.h>
#include <string.h>
#include <sys/socket.h>
#include <sys/types.h>
#include <netdb.h>
#include <errno.h>
#include <arpa/inet.h>
#include <signal.h>
#include <netinet/in.h>
#include "ping.h"
struct itimerval val_alarm={.it_interval.tv_sec = 1,
.it_interval.tv_usec = 0,
.it_value.tv_sec = 0,
.it_value.tv_usec = 1
};
int main(int argc, char **argv)
{
struct hostent *host;
if (argc < 2){
printf("Usuage: %s hostname\n", argv[0]);
exit(1);
}
if (host = gethostbyname(argv[1]) == NULL){
perror("can not understand the host name");
exit(1);
}
hostname = argv[1];
memset(&dest, 0, sizeof(dest));
dest.sin_family = PF_INET;
dest.sin_port = ntohs(0);
dest.sin_addr = *(struct in_addr *)host->h_addr_list[0];
if ((sockfd = socket(PF_INET, SOCK_RAW, IPPROTO_ICMP)) < 0){
perror("raw socket created error");
exit(1);
}
setuid(getuid());
pid = getpid();
set_sighandler();
printf("Ping %s(%s): %d bytes data in ICMP packets.\n\n",
argv[1], inet_ntoa(dest.sin_addr), datalen);
if ((setitimer(ITIMER_REAL, &val_alarm, NULL)) == -1)
bail("setitimer fails.");
recv_reply();
return 0;
}
void send_ping(void)
{
struct icmphdr *icmp_hdr;
int len;
icmp_hdr = (struct icmphdr *)sendbuf;
icmp_hdr->type = ICMP_ECHO;
icmp_hdr->code = 0;
icmp_hdr->icmp_id = pid;
icmp_hdr->icmp_seq = nsent++;
memset(icmp_hdr->data, 0xff, datalen);
gettimeofday((struct timeval *)icmp_hdr->data, NULL);
len = ICMP_HSIZE + datalen;
icmp_hdr->checksum = 0;
icmp_hdr->checksum = checksum((u8 *)icmp_hdr, len);
sendto(sockfd, sendbuf, len, 0, (struct sockaddr *)&dest, sizeof(dest));
}
void recv_reply()
{
int n, len;
int errno;
n = nrecv = 0;
len = sizeof(from);
while (nrecv < 3){
if ((n = recvfrom(sockfd, recvbuf, sizeof(recvbuf), 0, (struct sockaddr *)&from, &len)) < 0){
if (errno == EINTR)
continue;
bail("recvfrom error");
}
gettimeofday(&recvtime, NULL);
if (handle_pkt())
continue;
nrecv++;
}
get_statistics(nsent, nrecv);
}
u16 checksum(u8 *buf, int len)
{
u32 sum = 0;
u16 *cbuf;
cbuf = (u16 *)buf;
while (len > 1){
sum += *cbuf++;
len -= 2;
}
if(len)
sum += *(u8 *)cbuf;
sum = (sum >> 16) + (sum & 0xffff);
sum += (sum >> 16);
return -sum;
}
int handle_pkt()
{
struct iphdr *ip;
struct icmphdr *icmp;
int ip_hlen;
u16 ip_datalen;
double rtt;
struct timeval *sendtime;
ip = (struct iphdr *)recvbuf;
ip_hlen = ip->hlen << 2;
ip_datalen = ntohs(ip->tot_len) - ip_hlen;
icmp = (struct icmphdr *)(recvbuf + ip_hlen);
if (checksum(u8 *)icmp, ip_datalen)
return -1;
if(icmp->icmp_id != pid)
return -1;
sendtime = (struct timeval *)icmp->data;
rtt = ((&recvtime)->tv_sec - sendtime->tv_sec)*1000 + ((&recvtime)->tv_usec - sendtime->tv_usec)/1000.0;
printf("%d bytes from %s: icmp_seq = %u ttl=%d rtt=%.3f ms\n",
ip_datalen,
inet_ntoa(from.sin_addr),
icmp->icmp_seq,
ip->ttl,
rtt);
return 0;
}
void set_sighandler()
{
act_alarm.sa_handler = alarm_handler;
if (sigaction(SIGALRM, &act_alarm, NULL) == -1)
bail("SIGALRM handler setting fails.");
act_int.sa_handler = int_handler;
if (sigaction(SIGINT, &act_int, NULL) == -1)
bail("SIGINT handler setting fails.");
}
void get_statistics(int nsent, int nrecv)
{
printf("---%s ping statistics ---\n", inet_ntoa(dest.sin_addr));
printf("%d packets transmitted, %d received, %0.0f%%" "packet loss\n",
nsent, nrecv, 1.0*(nsent - nrecv)/nsent*100);
}
void bail(const char *on_what)
{
fputs(strerror(errno), stderr);
fputs(":", stderr);
fputs(on_what, stderr);
fputc('\n', stderr);
exit(1);
}
void int_handler(int sig)
{
get_statistics(nsent, nrecv);
close(sockfd);
exit(1);
}
void alarm_handler(int signo)
{
send_ping();
}
----没有理解,没有编译,只是敲了出来
ping.h
#define ICMP_ECHOREPLY 0
#define ICMP_ECHO 8
#define BUFSIZE 1500
#define DEFAULT_LEN 56
typedef unsigned char u8;
typedef unsigned short u16;
typedef unsigned int u32;
struct icmphdr{
u8 type;
u8 code;
u16 checksum;
union{
struct {
u16 id;
u16 sequence;
}echo;
u32 gateway;
struct
{
u16 unused;
u16 mtu;
}frag;
}un;
u8 data[0];
#define icmp_id un.echo.id
#define icmp_seq un.echo.sequence
};
#define ICMP_HSIZE sizeof(struct icmphdr)
struct iphdr{
u8 hlen:4, ver:4;
u8 tos;
u16 tot_len;
u16 id;
u16 frag_off;
u8 ttl;
u8 protocol;
u16 check;
u32 saddr;
u32 daddr;
};
char *hostname;
int datalen = DEFAULT_LEN;
char sendbuf[BUFSIZE];
char recvbuf[BUFSIZE];
int nsent;
int nrecv;
pid_t pid;
struct timeval recvtime;
int sockfd;
struct sockaddr_in dest;
struct sockaddr_in from;
struct sigaction act_alarm;
struct sigaction act_int;
void alarm_handler(int);
void int_handler(int);
void set_sighandler();
void send_ping();
void recv_reply();
u16 checksum(u8 *buf, int len);
int handle_pkt();
void get_statistics(int, int);
void bail(const char *)
ping.c
#include <stdio.h>
#include <stdlib.h>
#include <sys/time.h>
#include <unistd.h>
#include <string.h>
#include <sys/socket.h>
#include <sys/types.h>
#include <netdb.h>
#include <errno.h>
#include <arpa/inet.h>
#include <signal.h>
#include <netinet/in.h>
#include "ping.h"
struct itimerval val_alarm={.it_interval.tv_sec = 1,
.it_interval.tv_usec = 0,
.it_value.tv_sec = 0,
.it_value.tv_usec = 1
};
int main(int argc, char **argv)
{
struct hostent *host;
if (argc < 2){
printf("Usuage: %s hostname\n", argv[0]);
exit(1);
}
if (host = gethostbyname(argv[1]) == NULL){
perror("can not understand the host name");
exit(1);
}
hostname = argv[1];
memset(&dest, 0, sizeof(dest));
dest.sin_family = PF_INET;
dest.sin_port = ntohs(0);
dest.sin_addr = *(struct in_addr *)host->h_addr_list[0];
if ((sockfd = socket(PF_INET, SOCK_RAW, IPPROTO_ICMP)) < 0){
perror("raw socket created error");
exit(1);
}
setuid(getuid());
pid = getpid();
set_sighandler();
printf("Ping %s(%s): %d bytes data in ICMP packets.\n\n",
argv[1], inet_ntoa(dest.sin_addr), datalen);
if ((setitimer(ITIMER_REAL, &val_alarm, NULL)) == -1)
bail("setitimer fails.");
recv_reply();
return 0;
}
void send_ping(void)
{
struct icmphdr *icmp_hdr;
int len;
icmp_hdr = (struct icmphdr *)sendbuf;
icmp_hdr->type = ICMP_ECHO;
icmp_hdr->code = 0;
icmp_hdr->icmp_id = pid;
icmp_hdr->icmp_seq = nsent++;
memset(icmp_hdr->data, 0xff, datalen);
gettimeofday((struct timeval *)icmp_hdr->data, NULL);
len = ICMP_HSIZE + datalen;
icmp_hdr->checksum = 0;
icmp_hdr->checksum = checksum((u8 *)icmp_hdr, len);
sendto(sockfd, sendbuf, len, 0, (struct sockaddr *)&dest, sizeof(dest));
}
void recv_reply()
{
int n, len;
int errno;
n = nrecv = 0;
len = sizeof(from);
while (nrecv < 3){
if ((n = recvfrom(sockfd, recvbuf, sizeof(recvbuf), 0, (struct sockaddr *)&from, &len)) < 0){
if (errno == EINTR)
continue;
bail("recvfrom error");
}
gettimeofday(&recvtime, NULL);
if (handle_pkt())
continue;
nrecv++;
}
get_statistics(nsent, nrecv);
}
u16 checksum(u8 *buf, int len)
{
u32 sum = 0;
u16 *cbuf;
cbuf = (u16 *)buf;
while (len > 1){
sum += *cbuf++;
len -= 2;
}
if(len)
sum += *(u8 *)cbuf;
sum = (sum >> 16) + (sum & 0xffff);
sum += (sum >> 16);
return -sum;
}
int handle_pkt()
{
struct iphdr *ip;
struct icmphdr *icmp;
int ip_hlen;
u16 ip_datalen;
double rtt;
struct timeval *sendtime;
ip = (struct iphdr *)recvbuf;
ip_hlen = ip->hlen << 2;
ip_datalen = ntohs(ip->tot_len) - ip_hlen;
icmp = (struct icmphdr *)(recvbuf + ip_hlen);
if (checksum(u8 *)icmp, ip_datalen)
return -1;
if(icmp->icmp_id != pid)
return -1;
sendtime = (struct timeval *)icmp->data;
rtt = ((&recvtime)->tv_sec - sendtime->tv_sec)*1000 + ((&recvtime)->tv_usec - sendtime->tv_usec)/1000.0;
printf("%d bytes from %s: icmp_seq = %u ttl=%d rtt=%.3f ms\n",
ip_datalen,
inet_ntoa(from.sin_addr),
icmp->icmp_seq,
ip->ttl,
rtt);
return 0;
}
void set_sighandler()
{
act_alarm.sa_handler = alarm_handler;
if (sigaction(SIGALRM, &act_alarm, NULL) == -1)
bail("SIGALRM handler setting fails.");
act_int.sa_handler = int_handler;
if (sigaction(SIGINT, &act_int, NULL) == -1)
bail("SIGINT handler setting fails.");
}
void get_statistics(int nsent, int nrecv)
{
printf("---%s ping statistics ---\n", inet_ntoa(dest.sin_addr));
printf("%d packets transmitted, %d received, %0.0f%%" "packet loss\n",
nsent, nrecv, 1.0*(nsent - nrecv)/nsent*100);
}
void bail(const char *on_what)
{
fputs(strerror(errno), stderr);
fputs(":", stderr);
fputs(on_what, stderr);
fputc('\n', stderr);
exit(1);
}
void int_handler(int sig)
{
get_statistics(nsent, nrecv);
close(sockfd);
exit(1);
}
void alarm_handler(int signo)
{
send_ping();
}
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