ping功能实现(ICMP)

简单记录下项目中ping功能实现

笔记：ping功能实现

void Handler::handlePingDepot(const char *ip)

{

    int mSize=50*1024;

    bzero(&mDestAddr,sizeof(mDestAddr));

    mDestAddr.sin_family = AF_INET;

    mDestAddr.sin_addr.s_addr = inet_addr(ip);

    if( (mSockFd = socket(AF_INET,SOCK_RAW,IPPROTO_ICMP)) < 0){

        LogE("socket error\n");

        return;

    }

    ::setsockopt(mSockFd,SOL_SOCKET,SO_RCVBUF,&mSize,sizeof(mSize) );

    mPid=getpid();

    recvICMPPacket();

}

void Handler::sendICMPPacket()

{

    int mPacketSize = 0;

    mSend++;

    int n;

    mPacketSize = setICMPHander(mSend);

    if((n = ::sendto(mSockFd, mSendPacket,mPacketSize, 0,(struct sockaddr *)&mDestAddr, sizeof(mDestAddr))) < 0){

        LogE("send icmp packet  error\n");

        return;

    }

}

int Handler::setICMPHander(int mSeq)

{

    int mPackSize;

    struct icmp *icmp;

    icmp = (struct icmp*)mSendPacket;

    icmp->icmp_type = ICMP_ECHO;

    icmp->icmp_code = 0;

    icmp->icmp_cksum = 0;

    icmp->icmp_seq = mSeq;

    icmp->icmp_id = mPid;

    mPackSize = 8 + dataLen;

    icmp->icmp_cksum = calCheckSum( (unsigned short *)icmp,mPackSize);

    return mPackSize;

}

void Handler::recvICMPPacket()

{

     int n;

     mPingTag = true;

     socklen_t mFromLen;

     int mMaxFds = 0;

     fd_set mReadFds;

     struct timeval mTimeout;

     mFromLen = sizeof(struct sockaddr_in);

     while(1){

         sendICMPPacket();

         mTimeout.tv_sec = mConfig->mSCUTimeout;

         mTimeout.tv_usec = 0;

         FD_ZERO(&mReadFds);

         FD_SET(mSockFd,&mReadFds);

         mMaxFds = mSockFd + 1;

         n = select(mMaxFds, &mReadFds, NULL, NULL, &mTimeout);

         if(n <= 0 ){

             LogE("ping %s icmp packet error\n",inet_ntoa(mDestAddr.sin_addr));

             mPingTag = false;

             break;

         }else{

             memset(mRecvPacket, 0, sizeof(mRecvPacket));

             if((n = ::recvfrom(mSockFd, mRecvPacket, sizeof(mRecvPacket), 0, (struct sockaddr *)&mFrom, &mFromLen)) < 0){

                 LogE("recv icmp packet error\n");

                 return;

             }

             if(parseICMPPacket(mRecvPacket, n) == true){

                 mIPCall->sendDepotMsg(mFlag);

                 mRecvPandown = true;

                 mSend = 0;

                 break;

             }

         }

     }

}

bool Handler::parseICMPPacket(char *buf, int len)

{

    int mIpHdrLen;

    struct ip *mIP;

    struct icmp *mICMP;

    mIP = (struct ip *)buf;

    mIpHdrLen = mIP->ip_hl << 2;

    mICMP = (struct icmp *)(buf + mIpHdrLen);

    len -= mIpHdrLen;

    if( len < 8){

        LogE("ICMP packets's length is less than 8\n");

        return false;

    }

    if( (mICMP->icmp_type == ICMP_ECHOREPLY) && (mICMP->icmp_id == mPid) ) {

        LogE("%d byte from %s: icmp_seq=%u ttl=%d sucess\n",

            len,

            inet_ntoa(mFrom.sin_addr),

            mICMP->icmp_seq,

            mIP->ip_ttl);

         return true;

     }else{

         return false;

     }

}

unsigned short Handler::calCheckSum(unsigned short *addr,int len)

{

    int mLeft = len;

    int sum=0;

    unsigned short *w = addr;

    unsigned short answer = 0;

    while(mLeft > 1){

        sum += *w++;

        mLeft -= 2;

    }

    if( mLeft == 1){

        *(unsigned char *)(&answer) = *(unsigned char *)w;

        sum += answer;

    }

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

    sum += (sum >> 16);

    answer =~ sum;

    return answer;

}

ping功能实现(ICMP)的相关教程结束。