作者:侯志江     單位:天津大學軟件學院       E-mail :tjuhzjemail@yahoo.com.cn   日期:2005年1月1日     
內容簡介: 編寫自己的一個ping程序,可以說是許多人邁出網絡編程的第一步吧!!這個ping程序的源代碼經過我的修改和調試,基本上可以取代windows中自帶的ping程序. 各個模塊后都有我的詳細注釋和修改日志,希望能夠對大家的學習有所幫助!!

/* 本程序的主要源代碼來自MSDN網站, 筆者只是做了一些改進和注釋! 另外需要注意的是在Build之前,必須加入ws2_32.lib庫文件,否則會提示"error LNK2001:"的錯誤！*/
Version 1.1 修改記錄:
     <1> 解決了socket阻塞的問題,從而能夠正確地處理超時的請求!
     <2> 增加了由用戶控制發送ICMP包的數目的功能(即命令的第二個參數)
     <3> 增加了對ping結果的統計功能.  
                                                          

#pragma pack(4)
#include   "winsock2.h"
#include   "stdlib.h"
#include   "stdio.h"
#define ICMP_ECHO 8
#define ICMP_ECHOREPLY 0
#define ICMP_MIN 8 // minimum 8 byte icmp packet (just header)
/* The IP header */
typedef struct iphdr {
unsigned int h_len:4; // length of the header
unsigned int 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;
unsigned char proto; // protocol (TCP, UDP etc)
unsigned short checksum; // IP checksum
unsigned int sourceIP;
unsigned int destIP;
}IpHeader;
//
// ICMP header
//
typedef struct icmphdr {
BYTE i_type;
BYTE i_code; /* type sub code */
USHORT i_cksum;
USHORT i_id;
USHORT i_seq;
/* This is not the std header, but we reserve space for time */
ULONG timestamp;
}IcmpHeader;
#define STATUS_FAILED 0xFFFF
#define DEF_PACKET_SIZE    32
#define DEF_PACKET_NUMBER  4    /* 發送數據報的個數 */
#define MAX_PACKET 1024
#define xmalloc(s) HeapAlloc(GetProcessHeap(),HEAP_ZERO_MEMORY,(s))
#define xfree(p) HeapFree (GetProcessHeap(),0,(p))
void fill_icmp_data(char *, int);
USHORT checksum(USHORT *, int);
int decode_resp(char *,int ,struct sockaddr_in *);
void Usage(char *progname){
fprintf(stderr,"Usage:\n");
fprintf(stderr,"%s [number of packets] [data_size]\n",progname);
fprintf(stderr,"datasize can be up to 1Kb\n");
ExitProcess(STATUS_FAILED);
}
int main(int argc, char **argv){
WSADATA wsaData;
SOCKET sockRaw;
struct sockaddr_in dest,from;
struct hostent * hp;
int bread,datasize,times;
int fromlen = sizeof(from);
int timeout = 1000;
int statistic = 0;  /* 用于統計結果 */  
char *dest_ip;
char *icmp_data;
char *recvbuf;
unsigned int addr=0;
USHORT seq_no = 0;
if (WSAStartup(MAKEWORD(2,1),&wsaData) != 0){
fprintf(stderr,"WSAStartup failed: %d\n",GetLastError());
ExitProcess(STATUS_FAILED);
}
if (argc <2 ) {
Usage(argv[0]);
}
sockRaw = WSASocket(AF_INET,SOCK_RAW,IPPROTO_ICMP,NULL, 0,WSA_FLAG_OVERLAPPED);
//
//注：為了使用發送接收超時設置(即設置SO_RCVTIMEO, SO_SNDTIMEO)，
//    必須將標志位設為WSA_FLAG_OVERLAPPED !
//
if (sockRaw == INVALID_SOCKET) {
fprintf(stderr,"WSASocket() failed: %d\n",WSAGetLastError());
ExitProcess(STATUS_FAILED);
}
bread = setsockopt(sockRaw,SOL_SOCKET,SO_RCVTIMEO,(char*)&timeout,
sizeof(timeout));
if(bread == SOCKET_ERROR) {
fprintf(stderr,"failed to set recv timeout: %d\n",WSAGetLastError());
ExitProcess(STATUS_FAILED);
}
timeout = 1000;
bread = setsockopt(sockRaw,SOL_SOCKET,SO_SNDTIMEO,(char*)&timeout,
sizeof(timeout));
if(bread == SOCKET_ERROR) {
fprintf(stderr,"failed to set send timeout: %d\n",WSAGetLastError());
ExitProcess(STATUS_FAILED);
}
memset(&dest,0,sizeof(dest));
hp = gethostbyname(argv[1]);
if (!hp){
addr = inet_addr(argv[1]);
}
if ((!hp) && (addr == INADDR_NONE) ) {
fprintf(stderr,"Unable to resolve %s\n",argv[1]);
ExitProcess(STATUS_FAILED);
}
if (hp != NULL)
memcpy(&(dest.sin_addr),hp->h_addr,hp->h_length);
else
dest.sin_addr.s_addr = addr;
if (hp)
dest.sin_family = hp->h_addrtype;
else
dest.sin_family = AF_INET;
dest_ip = inet_ntoa(dest.sin_addr);
//
//  atoi函數原型是: int atoi( const char *string );
//  The return value is 0 if the input cannot be converted to an integer !
//
if(argc>2)
{
times=atoi(argv[2]);
if(times == 0)
  times=DEF_PACKET_NUMBER;
}
else
    times=DEF_PACKET_NUMBER;
if (argc >3)
{
datasize = atoi(argv[3]);
    if (datasize == 0)
        datasize = DEF_PACKET_SIZE;
if (datasize >1024)   /* 用戶給出的數據包大小太大 */
{
  fprintf(stderr,"WARNING : data_size is too large !\n");
  datasize = DEF_PACKET_SIZE;
}
}
else
    datasize = DEF_PACKET_SIZE;
datasize += sizeof(IcmpHeader);
icmp_data = (char*)xmalloc(MAX_PACKET);
recvbuf = (char*)xmalloc(MAX_PACKET);
if (!icmp_data) {
fprintf(stderr,"HeapAlloc failed %d\n",GetLastError());
ExitProcess(STATUS_FAILED);
}

memset(icmp_data,0,MAX_PACKET);
fill_icmp_data(icmp_data,datasize);
//
//顯示提示信息
//
fprintf(stdout,"\nPinging %s ....\n\n",dest_ip);

for(int i=0;i{
int bwrote;
((IcmpHeader*)icmp_data)->i_cksum = 0;
((IcmpHeader*)icmp_data)->timestamp = GetTickCount();
((IcmpHeader*)icmp_data)->i_seq = seq_no++;
((IcmpHeader*)icmp_data)->i_cksum = checksum((USHORT*)icmp_data,datasize);
bwrote = sendto(sockRaw,icmp_data,datasize,0,(struct sockaddr*)&dest,sizeof(dest));
if (bwrote == SOCKET_ERROR){
if (WSAGetLastError() == WSAETIMEDOUT) {
printf("Request timed out.\n");
continue;
}
fprintf(stderr,"sendto failed: %d\n",WSAGetLastError());
ExitProcess(STATUS_FAILED);
}
if (bwrote < datasize ) {
fprintf(stdout,"Wrote %d bytes\n",bwrote);
}
bread = recvfrom(sockRaw,recvbuf,MAX_PACKET,0,(struct sockaddr*)&from,&fromlen);
if (bread == SOCKET_ERROR){
if (WSAGetLastError() == WSAETIMEDOUT) {
printf("Request timed out.\n");
continue;
}
fprintf(stderr,"recvfrom failed: %d\n",WSAGetLastError());
ExitProcess(STATUS_FAILED);
}
if(!decode_resp(recvbuf,bread,&from))
statistic++; /* 成功接收的數目++ */
Sleep(1000);
}

/*
Display the statistic result
*/
fprintf(stdout,"\nPing statistics for %s \n",dest_ip);
fprintf(stdout,"    Packets: Sent = %d,Received = %d, Lost = %d (%2.0f%% loss)\n",times,
     statistic,(times-statistic),(float)(times-statistic)/times*100);

WSACleanup();
return 0;
}
/*
The response is an IP packet. We must decode the IP header to locate
the ICMP data
*/
int decode_resp(char *buf, int bytes,struct sockaddr_in *from) {
IpHeader *iphdr;
IcmpHeader *icmphdr;
unsigned short iphdrlen;
iphdr = (IpHeader *)buf;
iphdrlen = (iphdr->h_len) * 4 ; // number of 32-bit words *4 = bytes
if (bytes < iphdrlen + ICMP_MIN) {
printf("Too few bytes from %s\n",inet_ntoa(from->sin_addr));
}
icmphdr = (IcmpHeader*)(buf + iphdrlen);
if (icmphdr->i_type != ICMP_ECHOREPLY) {
fprintf(stderr,"non-echo type %d recvd\n",icmphdr->i_type);
return 1;
}
if (icmphdr->i_id != (USHORT)GetCurrentProcessId()) {
fprintf(stderr,"someone else''s packet!\n");
return 1;
}
printf("%d bytes from %s:",bytes, inet_ntoa(from->sin_addr));
printf(" icmp_seq = %d. ",icmphdr->i_seq);
printf(" time: %d ms ",GetTickCount()-icmphdr->timestamp);
printf("\n");
return 0;
}

USHORT checksum(USHORT *buffer, int size) {
unsigned long cksum=0;
while(size >1) {
cksum+=*buffer++;
size -=sizeof(USHORT);
}
if(size) {
cksum += *(UCHAR*)buffer;
}
cksum = (cksum >> 16) + (cksum & 0xffff);
cksum += (cksum >>16);
return (USHORT)(~cksum);
}
/*
Helper function to fill in various stuff in our ICMP request.
*/
void fill_icmp_data(char * icmp_data, int datasize){
IcmpHeader *icmp_hdr;
char *datapart;
icmp_hdr = (IcmpHeader*)icmp_data;
icmp_hdr->i_type = ICMP_ECHO;
icmp_hdr->i_code = 0;
icmp_hdr->i_id = (USHORT)GetCurrentProcessId();
icmp_hdr->i_cksum = 0;
icmp_hdr->i_seq = 0;
datapart = icmp_data + sizeof(IcmpHeader);
//
// Place some junk in the buffer.
//
memset(datapart,''E'', datasize - sizeof(IcmpHeader));
}
/******************* 附: ping命令執行時顯示的畫面 ****************\
*  C:\Documents and settings\houzhijiang>ping   236.56.54.12                              * *                                                                                                                          *
*  Pinging 236.56.54.12 with 32 bytes of data:                                                      *
*                                                                                                                          *
*  Request timed out.                                                                                            *
*  Request timed out.                                                                                            *
*  Request timed out.                                                                                            *
*  Request timed out.                                                                                            *
*                                                                                                                          *
*  Ping statistics for 236.56.54.12:                                                                        *
*     Packets: Sent = 4, Received = 0, Lost = 4 (100% loss),                                *
*                                                                                                                         *
\**************************************************************/
/**************************************************************\
*  C:\Documents and Settings\houzhijiang>ping 127.0.0.1                                    *
*                                                                                                                         *
*  Pinging 127.0.0.1 with 32 bytes of data:                                                           *
*                                                                                                                         *
*  Reply from 127.0.0.1: bytes=32 time<1ms TTL=128                                      *
*  Reply from 127.0.0.1: bytes=32 time<1ms TTL=128                                      *
*  Reply from 127.0.0.1: bytes=32 time<1ms TTL=128                                      *
*  Reply from 127.0.0.1: bytes=32 time<1ms TTL=128                                      *
*                                                                                                                         *
*  Ping statistics for 127.0.0.1:                                                                             *
*     Packets: Sent = 4, Received = 4, Lost = 0 (0% loss),                                   *
*  Approximate round trip times in milli-seconds:                                                  *
*     Minimum = 0ms, Maximum = 0ms, Average = 0ms                                       *
*                                                                                                                         *
\**************************************************************/