为什么我的ICMP包发出去后对方没有回应？

[Alecksun]

处学SOCK_RAW编程，想做一个Ping程序，但是发出ICMP数据报后对方没有回应，谁能告诉我为什么？
--------------------------------------------
typedef struct
{
unsigned char type;
unsigned char code;
unsigned short checksum;
union
{
struct
{
unsigned short id;
unsigned short sn;
}reply;
}Data;
}ICMP_HEADER
--------------------------------------------------------
unsigned int checksum(unsigned int *val,unsigned int length) //计算校验和
{
unsigned int sum = 0;
unsigned int left = length;
while(length > 1)
{
sum += *val;
val ++;
length -= 2;
}
if(length)
sum += (*val) & (0x00ff);
return ~sum;
}


int main(int argc ,char *argv[])
{
WSADATA wsaData;
WSAStartup(MAKEWORD(2,2),&wsaData);

SOCKET sockRAW;
SOCKADDR_IN dst,src;
int timeout =1000;
sockRAW = WSASocket(AF_INET,SOCK_RAW,IPPROTO_ICMP,NULL,0,WSA_FLAG_OVERLAPPED);
int rev = setsockopt(sockRAW,SOL_SOCKET,SO_SNDTIMEO,(const char*)&timeout,sizeof(int));
if(rev == SOCKET_ERROR)
printf("Cannot Set SndTimedout\n");
rev = setsockopt(sockRAW,SOL_SOCKET,SO_RCVTIMEO,(const char*)&timeout,sizeof(int));
if(rev == SOCKET_ERROR)
printf("Cannot set RcvTimedout\n");
int ttl = 128;
setsockopt(sockRAW,IPPROTO_IP,IP_TTL,(const char*)&ttl,sizeof(int));

char *buf = new char[MAXBUF+1];

ICMP_HEADER *icmphdr;
icmphdr = (ICMP_HEADER*)buf;
icmphdr->type = 8;
icmphdr->code = 0;
icmphdr->checksum = 0;
icmphdr->Data.reply.id = GetCurrentProcessId();
icmphdr->Data.reply.sn = 0;
memset(buf+sizeof(icmphdr)+4,'*',PACKET);
*(unsigned long*)(buf + sizeof(ICMP_HEADER)) = GetTickCount();
icmphdr->checksum = checksum((unsigned int*)&icmphdr,sizeof(icmphdr)+PACKET);

dst.sin_family = AF_INET;
dst.sin_addr .s_addr = inet_addr("192.168.0.1");


rev = sendto(sockRAW,buf,sizeof(icmphdr) + PACKET,0,(SOCKADDR*)&dst,sizeof(dst));
if(rev == SOCKET_ERROR)
{
if(WSAGetLastError() == WSAETIMEDOUT)
printf("Send Timedout\n");
else(" Connot reach host");
exit(0);
}
printf("Sendind...\n");

char *revbuf = new char[sizeof(src) + PACKET];
int len = sizeof(icmphdr) + PACKET;
recvfrom(sockRAW,revbuf,sizeof(src) + PACKET , 0 , (SOCKADDR *)&src,&len);
if(rev == SOCKET_ERROR)
{
if((rev = WSAGetLastError()) == WSAETIMEDOUT)
printf("Recieve Timedout\n");
else
printf("other error");
}
return 0;


}

----------------------------------------------------
从网络监视器上看到ICMP包已经发出去了，对方没有回应,但recvfrom也没返回超时，不知这是怎么回事？
那位大哥告诉我，小弟不胜感激，100分相送。

[dzhcheng]

给一个ping的实现程序你，慢慢看！

#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <time.h>

#ifdef WIN32

#define WIN32_LEAN_AND_MEAN
#include <winsock.h>
#pragma comment(lib, "Wsock32.lib")

#else

#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <netdb.h>
#include <sys/ioctl.h>
#include <arpa/inet.h>
#include <unistd.h>
#include <netinet/ip.h>
#include <netinet/ip_icmp.h>

#endif

#define ICMP_ECHO 8
#define ICMP_ECHOREPLY 0

//#define ICMP_MIN 8 // minimum 8 byte icmp packet (just header)
#define ICMP_MIN (8 + 4) // minimum 8 byte icmp packet (just header + timestamp)

// IP header
typedef struct _tagX_iphdr
{
unsigned char h_len:4; // length of the header
unsigned char version:4; // Version of IP
unsigned char tos; // Type of service
unsigned short total_len; // total length of the packet

unsigned short ident; // unique identifier
unsigned short frag_and_flags; // flags

unsigned char ttl; // ttl
unsigned char proto; // protocol (TCP, UDP etc)
unsigned short checksum; // IP checksum

unsigned int sourceIP;
unsigned int destIP;
}XIpHeader;

// ICMP header
typedef struct _tagX_icmphdr
{
unsigned char i_type;
unsigned char i_code;
unsigned short i_cksum;
unsigned short i_id;
unsigned short i_seq;
unsigned long i_timestamp;
}XIcmpHeader;

//puclic code
//网际校验和生产算法
//网际校验和是被校验数据16位值的反码和(ones-complement sum)
unsigned short in_cksum(unsigned short* addr, int len)
{
int nleft = len;
int sum = 0;
unsigned short* w = addr;
unsigned short answer = 0;

while(nleft > 1) {
sum += *w++;
nleft -= 2;
}

if(nleft == 1) {
*(unsigned char*)(&answer) = *(unsigned char*)w;
sum += answer;
}

sum = (sum >> 16) + (sum & 0xffff);
sum += (sum >> 16);
answer = ~sum;

return (answer);
}

void fill_IpHeader(char *buf)
{
// XIpHeader *ip_hdr = (XIpHeader *)buf;
}

void fill_IcmpData(char *buf, int datasize)
{
if (buf)
{
char ch = 0;
char* icmpdata = buf + sizeof(XIcmpHeader);
fprintf(stdout, "(IcmpData)\r\n");
for (int i = 0; i < datasize; i++)
{
ch = 'A' + i%('z' - 'A');
*(icmpdata + i) = ch;
fprintf(stdout, "%c", ch);
}
fprintf(stdout, "\r\n");
}
}

void fill_IcmpHeader(char *buf, int datasize)
{
static unsigned short seq_no = 0;
XIcmpHeader *icmp_hdr = (XIcmpHeader *)buf;
if (icmp_hdr)
{
icmp_hdr->i_type = ICMP_ECHO;
icmp_hdr->i_code = 0;
icmp_hdr->i_cksum = 0;

#ifdef WIN32
icmp_hdr->i_id = (unsigned short)GetCurrentProcessId();
#else
icmp_hdr->i_id = (unsigned short)getpid();
#endif
icmp_hdr->i_seq = seq_no++;

#ifdef WIN32
icmp_hdr->i_timestamp = (unsigned long)::GetTickCount();
#else
icmp_hdr->i_timestamp = (unsigned long)time(NULL);
#endif

icmp_hdr->i_cksum = in_cksum((unsigned short*)buf, sizeof(XIcmpHeader) + datasize);

fprintf(stdout, "(IcmpHeader)\r\n");
fprintf(stdout, "%02X%02X%04X\r\n", icmp_hdr->i_type, icmp_hdr->i_code, icmp_hdr->i_cksum);
fprintf(stdout, "%04X%04X\r\n", icmp_hdr->i_id, icmp_hdr->i_seq);
fprintf(stdout, "%08X\r\n", icmp_hdr->i_timestamp);
}
}

// decode
void decode_IpIcmp(char *buf, int size)
{
XIpHeader *ip_hdr = (XIpHeader *)buf;
unsigned short iphdrlen;
if (ip_hdr)
{
fprintf(stdout, "(IpHeader)\r\n");
fprintf(stdout, "%01X%01X%02X%04X\r\n", ip_hdr->version, ip_hdr->h_len, ip_hdr->tos, ip_hdr->total_len);
fprintf(stdout, "%04X%04X\r\n", ip_hdr->ident, ip_hdr->frag_and_flags);
fprintf(stdout, "%02X%02X%04X\r\n", ip_hdr->ttl, ip_hdr->proto, ip_hdr->checksum);

//iphdrlen = ip_hdr->h_len * 4; // number of 32-bit words *4 = bytes
iphdrlen = ip_hdr->h_len << 2; // number of 32-bit words *4 = bytes
fprintf(stdout, "(IcmpHeader)\r\n");
if (size < iphdrlen + ICMP_MIN)
{
fprintf(stdout, "Reply %d bytes Too few\r\n", size);
}
else
{
XIcmpHeader *icmp_hdr = (XIcmpHeader *)(buf + iphdrlen);

fprintf(stdout, "%02X%02X%04X\r\n", icmp_hdr->i_type, icmp_hdr->i_code, icmp_hdr->i_cksum);
fprintf(stdout, "%04X%04X\r\n", icmp_hdr->i_id, icmp_hdr->i_seq);
fprintf(stdout, "%08X\r\n", icmp_hdr->i_timestamp);
/*
fprintf(stdout, "(IcmpData)\r\n");
int iIcmpDataSize = size - iphdrlen - sizeof(XIcmpHeader);
char *icmpdata = buf + iIcmpDataSize;
for (int i = 0; i < iIcmpDataSize; i++)
fprintf(stdout, "%c", *(icmpdata + i));
fprintf(stdout, "\r\n");
*/
unsigned long timestamp = 0;
#ifdef WIN32
timestamp = (unsigned long)::GetTickCount();
#else
timestamp = (unsigned long)time(NULL);;
#endif
timestamp -= icmp_hdr->i_timestamp;

struct sockaddr_in from;
from.sin_addr.s_addr = ip_hdr->sourceIP;

fprintf(stdout, "Reply %d bytes from: %s time<%d TTL=%d icmp_seq=%d\r\n",
size,
inet_ntoa(from.sin_addr),
timestamp,
ip_hdr->ttl,
icmp_hdr->i_seq
);
}
}
}

int main(int argc, char **argv)
{
int ret = 0;

#ifdef WIN32
WSADATA ws;
WSAStartup(0x0101,&ws);
//#else
// ;
#endif

int iIcmpDataSize = 0;
struct sockaddr_in dest,from;
unsigned int addr = 0;
struct hostent *hp;

char buffer[1024];
char recv_buffer[1024];

if(argc < 2)
{
fprintf(stderr, "Usage: %s [host|ip] [datasize]\r\n", argv[0]);
return 0;
}

if (argc > 2)
iIcmpDataSize = atoi(argv[2]);
if (iIcmpDataSize < 1 || iIcmpDataSize > 1024)
iIcmpDataSize = 10;

memset(&dest, 0, sizeof dest);
dest.sin_family = AF_INET;
hp = gethostbyname(argv[1]);
if (!hp)
addr = inet_addr(argv[1]);
if ((!hp) && (addr == INADDR_NONE))
{
fprintf(stderr,"Unable to resolve %s\r\n",argv[1]);
return 0;
}
if (hp != NULL)
memcpy(&(dest.sin_addr), hp->h_addr,hp->h_length);
else
dest.sin_addr.s_addr = addr;

#ifdef WIN32
// ;
#else
setuid(getuid());
// setuid(0);
#endif
int sockfd;
sockfd = socket(AF_INET, SOCK_RAW, IPPROTO_ICMP);

fprintf(stdout, "XPing...\r\n");
for (int i = 0; i < 3; i++)
{
fprintf(stdout, "Echo...\r\n");
memset(buffer, 0, 1024);
fill_IcmpData(buffer, iIcmpDataSize);
fill_IcmpHeader(buffer, iIcmpDataSize);
XIcmpHeader *icmp_hdr = (XIcmpHeader *)buffer;
int iSendSize = sendto(sockfd, buffer, sizeof(XIcmpHeader) + iIcmpDataSize, 0, (struct sockaddr*)&dest, sizeof(dest));

fprintf(stdout, "Reply...\r\n");
memset(&from, 0, sizeof from);
memset(recv_buffer, 0, 1024);
#ifdef WIN32
int fromlen = sizeof(from);
int iRecvSize = recvfrom(sockfd, recv_buffer, 1024, 0, (struct sockaddr*)&from, &fromlen);
#else
socklen_t fromlen = sizeof(from);
int iRecvSize = recvfrom(sockfd, recv_buffer, 1024, 0, (struct sockaddr*)&from, &fromlen);
#endif
if (iRecvSize > 0)
decode_IpIcmp(recv_buffer, iRecvSize);
}

#ifdef WIN32
WSACleanup();
//#else
// ;
#endif

return ret;
}

[EA888016]

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