基于ICMP的一个ping程序

最新推荐文章于 2018-12-01 17:24:26 发布

原创最新推荐文章于 2018-12-01 17:24:26 发布 · 795 阅读

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#socket #struct

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本文介绍了一个使用C语言实现的自定义Ping程序，该程序详细展示了如何构造和发送ICMP请求包，以及如何解析和处理回应。通过创建原始套接字并设置超时，程序能够向指定的目标IP地址发送ICMP回显请求，并接收回显应答。

typedef struct icmp_hdr
{
unsigned char icmp_type; //消息类型
unsigned char icmp_code; //代码
unsigned short icmp_checksum;

unsigned short icmp_id;
unsigned short icmp_sequence;

unsigned long icmp_timestamp;
}ICMP_HDR,*PICMP_HDR;

typedef struct _IPHeader
{
UCHAR iphVerLen;
UCHAR ipTOS;
USHORT ipLength;
USHORT ipID;
USHORT ipFlags;
UCHAR ipTTL;
UCHAR ipProtocol;
USHORT ipChecksum;
ULONG ipSource;
ULONG ipDestination;
}IPHeader,*PIPHeader;

void Ping()

{

char szDestIp[] = "127.0.0.1";
CString sLog,stemp;
WSADATA wsaData;
WORD sockVersion = MAKEWORD(2,2);

if(WSAStartup(sockVersion,&wsaData) != 0)
{
return ;
}

SOCKET sRaw = socket(AF_INET,SOCK_RAW,IPPROTO_ICMP);

SetTimeout(sRaw,1000,TRUE);

SOCKADDR_IN dest;
dest.sin_family = AF_INET;
dest.sin_port = htons(0);
dest.sin_addr.S_un.S_addr = inet_addr(szDestIp);

char buff[sizeof(ICMP_HDR)+32];
ICMP_HDR *pIcmp = (ICMP_HDR*)buff;

pIcmp->icmp_type = 8;
pIcmp->icmp_code = 0;
pIcmp->icmp_id = (USHORT)GetCurrentProcessId();
pIcmp->icmp_checksum = 0;
pIcmp->icmp_sequence = 0;
memset(&buff[sizeof(ICMP_HDR)],'E',32);

USHORT nSeq = 0;
char recvBuf[1024];
SOCKADDR_IN from;
int nLen = sizeof(from);

BOOL ret = FALSE;

while(TRUE)
{
  static int nCount = 0;
  int nRet;
  if( nCount++ ==4)
   break;

  pIcmp->icmp_checksum = 0;
  pIcmp->icmp_timestamp = GetTickCount();
  pIcmp->icmp_sequence = nSeq;
  pIcmp->icmp_checksum = checksum((USHORT*)buff,sizeof(ICMP_HDR)+32);
  nRet = sendto(sRaw,buff,sizeof(ICMP_HDR)+32,0,(SOCKADDR*)&dest,sizeof(dest));
  if(nRet == SOCKET_ERROR)
  {
   break;
  }

nRet = recvfrom(sRaw,recvBuf,1024,0,(sockaddr*)&from,&nLen);

  if(nRet == SOCKET_ERROR)
  {
   if(WSAGetLastError() == WSAETIMEDOUT)
   {
    //time out
    sLog.Format("Request timed out/n");
    GetDlgItemText(IDC_EDIT_TEST,stemp);
    SetDlgItemText(IDC_EDIT_TEST,stemp + sLog);
    continue;
   }
   // failed
   return ;
  }

  int nTick = ::GetTickCount();
  if(nRet < sizeof(IPHeader)+sizeof(ICMP_HDR))
  {
   sLog.Format("Too few bytes from %s /n",::inet_ntoa(from.sin_addr));
   GetDlgItemText(IDC_EDIT_TEST,stemp);
   SetDlgItemText(IDC_EDIT_TEST,stemp + sLog);
  }

  ICMP_HDR* pRecvIcmp = (ICMP_HDR*)(recvBuf + 20); // (ICMP_HDR*)(recvBuf + sizeof(IPHeader));
        if(pRecvIcmp->icmp_type != 0)    // 回显
        {
            sLog.Format("nonecho type %d recvd /n",pRecvIcmp->icmp_type);
            GetDlgItemText(IDC_EDIT_TEST,stemp);
            SetDlgItemText(IDC_EDIT_TEST,stemp + sLog);
            return ;
        }

        if(pRecvIcmp->icmp_id != ::GetCurrentProcessId())
        {
            sLog.Format("someone else's packet! /n");
            GetDlgItemText(IDC_EDIT_TEST,stemp);
            SetDlgItemText(IDC_EDIT_TEST,stemp + sLog);
            return ;
        }
        sLog.Format("%d bytes from %s: /r/n   icmp_seq = %d. time: %d ms /r/n",
   nRet, inet_ntoa(from.sin_addr), pRecvIcmp->icmp_sequence,
   nTick - pRecvIcmp->icmp_timestamp);
  GetDlgItemText(IDC_EDIT_TEST,stemp);
  SetDlgItemText(IDC_EDIT_TEST,stemp + sLog);

ret |= TRUE;

::Sleep(1000);
}

}

USHORT checksum(USHORT* buff,int size)
{
unsigned long cksum = 0;
while(size>1)
{
  cksum += *buff++;
  size -= sizeof(USHORT);
}
if(size)
{
  cksum += *(UCHAR*)buff;
}
cksum = (cksum>>16)+(cksum & 0xffff);
cksum += (cksum>>16);
return (USHORT)(~cksum);
}

BOOL SetTimeout(SOCKET s,int nTime,BOOL bRecv)
{
int ret = setsockopt(s,SOL_SOCKET,bRecv ? SO_RCVTIMEO : SO_SNDTIMEO,(char*)&nTime,sizeof(nTime));
return ret != SOCKET_ERROR;
}