我使用此代码发送数据（IPPROTO_ICMP），使用套接字发送和接收数据
#include <stdio.h>
#include <stdlib.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <netdb.h>
#include <linux/ip.h>
#include <linux/icmp.h>
#include <string.h>
#include <unistd.h>
char dst_addr[20];
char src_addr[20];
unsigned short in_cksum(unsigned short *, int);
void parse_argvs(char**, char*, char* );
void usage();
char* getip();
char* toip(char*);
int main(int argc, char* argv[])
{
struct iphdr* ip;
struct iphdr* ip_reply;
struct icmphdr* icmp;
struct icmphdr* icmp_reply;
struct sockaddr_in connection;
char* packet;
char* buffer;
int sockfd;
int optval;
int addrlen;
int siz;
int i;
//int toto=0;
//struct timeval timeout;
//timeout.tv_sec = 10;
//timeout.tv_usec = 0;
if (getuid() != 0)
{
fprintf(stderr, "%s: root privelidges needed\n", *(argv + 0));
exit(EXIT_FAILURE);
}
//icmp_type = 11;
parse_argvs(argv, dst_addr, src_addr);
strncpy(dst_addr, toip(dst_addr), 20);
strncpy(src_addr, toip(src_addr), 20);
printf("Source address: %s\n", src_addr);
printf("Destination address: %s\n", dst_addr);
/*
* allocate all necessary memory
*/
packet = malloc(sizeof(struct iphdr) + sizeof(struct icmphdr));
buffer = malloc(sizeof(struct iphdr) + sizeof(struct icmphdr));
/****************************************************************/
ip = (struct iphdr*) packet;
icmp = (struct icmphdr*) (packet + sizeof(struct iphdr));
/*
* here the ip packet is set up
*/
ip->ihl = 5;
ip->version = 4;
ip->tos = 0;
ip->tot_len = sizeof(struct iphdr) + sizeof(struct icmphdr);
ip->id = htons(0);
ip->frag_off = 0;
ip->ttl = 1;
ip->protocol = IPPROTO_ICMP;
ip->saddr = inet_addr(src_addr);
ip->daddr = inet_addr(dst_addr);
ip->check = in_cksum((unsigned short *)ip, sizeof(struct iphdr));
if ((sockfd = socket(AF_INET, SOCK_RAW, IPPROTO_ICMP)) == -1)
{
perror("socket");
exit(EXIT_FAILURE);
}
printf("=====> sockfd= %d \n",sockfd);
/*
* IP_HDRINCL must be set on the socket so that
* the kernel does not attempt to automatically add
* a default ip header to the packet
*/
setsockopt(sockfd, IPPROTO_IP, IP_HDRINCL, &optval, sizeof(int));
/*
if (setsockopt (sockfd, SOL_SOCKET, SO_RCVTIMEO, (char *)&timeout,
sizeof(timeout)) < 0)
error("setsockopt failed\n");
if (setsockopt (sockfd, SOL_SOCKET , SO_SNDTIMEO, (char *)&timeout,
sizeof(timeout)) < 0)
error("setsockopt failed\n");*/
/*
* here the icmp packet is created
* also the ip checksum is generated
*/
icmp->type = ICMP_ECHO;
icmp->code = 0;
icmp->un.echo.id = random();
icmp->un.echo.sequence = 0;
icmp-> checksum = in_cksum((unsigned short *)icmp, sizeof(struct icmphdr));
connection.sin_family = AF_INET;
connection.sin_addr.s_addr = inet_addr(dst_addr);
/*
* now the packet is sent
*/
//ssize_t sendto(int sockfd, const void *buf, size_t len, int flags,
// const struct sockaddr *dest_addr, socklen_t addrlen);
//toto=11;
for(ip->ttl =1;ip->ttl <25 /*&& (icmp_type==11)*/;ip->ttl++)
{
sendto(sockfd, packet, ip->tot_len, 0, (struct sockaddr *)&connection, sizeof(struct sockaddr));
printf("Sent %d byte packet to %s , >>>>> TTL=%d\n", ip->tot_len, dst_addr,ip->ttl);
for (i = 0; i < ip->tot_len; i++) {
printf("%02X%s", (uint8_t)packet[i], (i + 1)%16 ? " " : "\n");
}
printf("\n");
printf("ICMP msgtype=%d, code=%d \n", icmp->type, icmp->code);
/*
* now we listen for responses
*/
addrlen = sizeof(connection);
printf("recvfrom 00\n");
if (( siz = recvfrom(sockfd, buffer, sizeof(struct iphdr) + sizeof(struct icmphdr), 0, (struct sockaddr *)&connection, &addrlen)) == -1)
{
perror("recv");
}
else
{
printf("recvfrom 11\n");
//printf("Received %d byte reply from %s:\n", siz , dst_addr);
printf("node num :[ %d] IP= %s:\n", ip->ttl, dst_addr);
ip_reply = (struct iphdr*) buffer;
icmp_reply = (struct icmphdr*)(buffer+sizeof(struct iphdr));
for (i = 0; i < siz; i++)
{
printf("%02X%s", (uint8_t)buffer[i], (i + 1)%16 ? " " : "\n");
}
printf("\n icmp_reply->type %d \n",icmp_reply->type);
printf("RCV ip->daddr = %s \n",inet_ntoa(*((struct in_addr *)&ip_reply->saddr)));
printf("\n");
printf("ID: %d\n", ntohs(ip_reply->id));
printf("TTL: %d\n", ip_reply->ttl);
}
printf("recvfrom 12\n");
}
free(packet);
free(buffer);
close(sockfd);
return 0;
}
void parse_argvs(char** argv, char* dst, char* src)
{
int i;
if(!(*(argv + 1)))
{
/* there are no options on the command line */
usage();
exit(EXIT_FAILURE);
}
if (*(argv + 1) && (!(*(argv + 2))))
{
/*
* only one argument provided
* assume it is the destination server
* source address is local host
*/
strncpy(dst, *(argv + 1), 15);
strncpy(src, getip(), 15);
return;
}
else if ((*(argv + 1) && (*(argv + 2))))
{
/*
* both the destination and source address are defined
* for now only implemented is a source address and
* destination address
*/
strncpy(dst, *(argv + 1), 15);
i = 2;
while(*(argv + i + 1))
{
if (strncmp(*(argv + i), "-s", 2) == 0)
{
strncpy(src, *(argv + i + 1), 15);
break;
}
i++;
}
}
}
void usage()
{
fprintf(stderr, "\nUsage: pinger [destination] <-s [source]>\n");
fprintf(stderr, "Destination must be provided\n");
fprintf(stderr, "Source is optional\n\n");
}
char* getip()
{
char buffer[256];
struct hostent* h;
gethostname(buffer, 256);
h = gethostbyname(buffer);
return inet_ntoa(*(struct in_addr *)h->h_addr);
}
/*
* return the ip address if host provided by DNS name
*/
char* toip(char* address)
{
struct hostent* h;
h = gethostbyname(address);
return inet_ntoa(*(struct in_addr *)h->h_addr);
}
/*
* in_cksum --
* Checksum routine for Internet Protocol
* family headers (C Version)
*/
unsigned short in_cksum(unsigned short *addr, int len)
{
register int sum = 0;
u_short answer = 0;
register u_short *w = addr;
register int nleft = len;
/*
* Our algorithm is simple, using a 32 bit accumulator (sum), we add
* sequential 16 bit words to it, and at the end, fold back all the
* carry bits from the top 16 bits into the lower 16 bits.
*/
while (nleft > 1)
{
sum += *w++;
nleft -= 2;
}
/* mop up an odd byte, if necessary */
if (nleft == 1)
{
*(u_char *) (&answer) = *(u_char *) w;
sum += answer;
}
/* add back carry outs from top 16 bits to low 16 bits */
sum = (sum >> 16) + (sum & 0xffff); /* add hi 16 to low 16 */
sum += (sum >> 16); /* add carry */
answer = ~sum; /* truncate to 16 bits */
return (answer);
}
问题是当我添加“toto”变量时，程序正在阻止
===＆GT;阻止时运行代码的结果
root@root:/home/aa/test# ./ping www.yahoo.com
Source address: 192.168.1.227
Destination address: 98.139.183.24
=====> sockfd= 3
Sent 28 byte packet to 98.139.183.24 , >>>>> TTL=1
45 00 1C 00 00 00 00 00 01 01 C1 CE C0 A8 01 E3
62 8B B7 18 08 00 90 BA 67 45 00 00
ICMP msgtype=8, code=0
recvfrom 00
这很奇怪，但是当我使用优化标志编译时，问题不会发生
==＆GT; gcc -O -o ping ping.c而不是使用gcc -O -o ping ping.c
这是第一个问题!!
我在setsockopt函数中使用超时时发生了第二个问题。 !!
代码中的我替换了这个函数
setsockopt(sockfd, IPPROTO_IP, IP_HDRINCL, &optval, sizeof(int));
by：
if (setsockopt (sockfd, SOL_SOCKET, SO_RCVTIMEO, (char *)&timeout,
sizeof(timeout)) < 0)
error("setsockopt failed\n");
if (setsockopt (sockfd, SOL_SOCKET , SO_SNDTIMEO, (char *)&timeout,
sizeof(timeout)) < 0)
error("setsockopt failed\n");
==＆GT;运行带有错误“recv：资源暂时不可用”的代码的结果
Source address: 192.168.1.227
Destination address: 98.139.183.24
=====> sockfd= 3
Sent 28 byte packet to 98.139.183.24 , >>>>> TTL=1
45 00 1C 00 00 00 00 00 01 01 C1 CE C0 A8 01 E3
62 8B B7 18 08 00 90 BA 67 45 00 00
ICMP msgtype=8, code=0
recvfrom 00
recv: Resource temporarily unavailable
recvfrom 12
Sent 28 byte packet to 98.139.183.24 , >>>>> TTL=2
45 00 1C 00 00 00 00 00 02 01 C1 CE C0 A8 01 E3
62 8B B7 18 08 00 90 BA 67 45 00 00
ICMP msgtype=8, code=0
recvfrom 00
recv: Resource temporarily unavailable
recvfrom 12
Sent 28 byte packet to 98.139.183.24 , >>>>> TTL=3
45 00 1C 00 00 00 00 00 03 01 C1 CE C0 A8 01 E3
62 8B B7 18 08 00 90 BA 67 45 00 00
ICMP msgtype=8, code=0
recvfrom 00