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附源码：ping.cpp ping.h 是类的实现。
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实例代码是从项目的应用中剥离出来的：
ping.cpp:
#include "ping.h"
Ping::Ping() {
m_maxPacketSize = 4;
m_datalen = 56;
m_nsend = 0;
m_nreceived = 0;
m_icmp_seq = 0;
}
/*校验和算法*/
unsigned short Ping::getChksum(unsigned short *addr,int len)
{
int nleft=len;
int sum=0;
unsigned short *w=addr;
unsigned short answer=0;
/*把ICMP报头二进制数据以2字节为单位累加起来*/
while(nleft>1)
{
sum+=*w++;
nleft-=2;
}
/*若ICMP报头为奇数个字节，会剩下最后一字节。把最后一个字节视为一个2字节数据的高字节，这个2字节数据的低字节为0，继续累加*/
if( nleft==1)
{
*(unsigned char *)(&answer)=*(unsigned char *)w;
sum+=answer;
}
sum=(sum>>16)+(sum&0xffff);
sum+=(sum>>16);
answer=~sum;
return answer;
}
/*设置ICMP报头*/
int Ping::packIcmp(int pack_no, struct icmp* icmp)
{
int i,packsize;
struct icmp *picmp;
struct timeval *tval;
picmp = icmp;
picmp->icmp_type=ICMP_ECHO;
picmp->icmp_code=0;
picmp->icmp_cksum=0;
picmp->icmp_seq=pack_no;
picmp->icmp_id= m_pid;
packsize= 8 + m_datalen;
tval= (struct timeval *)icmp->icmp_data;
gettimeofday(tval,NULL); /*记录发送时间*/
picmp->icmp_cksum=getChksum((unsigned short *)icmp,packsize); /*校验算法*/
return packsize;
}
/*剥去ICMP报头*/
bool Ping::unpackIcmp(char *buf,int len, struct IcmpEchoReply *icmpEchoReply)
{
int i,iphdrlen;
struct ip *ip;
struct icmp *icmp;
struct timeval *tvsend, tvrecv, tvresult;
double rtt;
ip = (struct ip *)buf;
iphdrlen = ip->ip_hl << 2; /*求ip报头长度,即ip报头的长度标志乘4*/
icmp = (struct icmp *)(buf + iphdrlen); /*越过ip报头,指向ICMP报头*/
len -= iphdrlen; /*ICMP报头及ICMP数据报的总长度*/
if(len < 8) /*小于ICMP报头长度则不合理*/
{
printf("ICMP packets\'s length is less than 8\n");
return false;
}
/*确保所接收的是我所发的的ICMP的回应*/
if( (icmp->icmp_type==ICMP_ECHOREPLY) && (icmp->icmp_id == m_pid) )
{
tvsend=(struct timeval *)icmp->icmp_data;
gettimeofday(&tvrecv,NULL); /*记录接收时间*/
tvresult = tvSub(tvrecv, *tvsend); /*接收和发送的时间差*/
rtt=tvresult.tv_sec*1000 + tvresult.tv_usec/1000; /*以毫秒为单位计算rtt*/
icmpEchoReply->rtt = rtt;
icmpEchoReply->icmpSeq = icmp->icmp_seq;
icmpEchoReply->ipTtl = ip->ip_ttl;
icmpEchoReply->icmpLen = len;
return true;
}
else {
return false;
}
}
/*两个timeval结构相减*/
struct timeval Ping::tvSub(struct timeval timeval1,struct timeval timeval2)
{
struct timeval result;
result = timeval1;
if (result.tv_usec < timeval2.tv_usec < 0)
{
--result.tv_sec;
result.tv_usec += 1000000;
}
result.tv_sec -= timeval2.tv_sec;
return result;
}
/*发送三个ICMP报文*/
bool Ping::sendPacket()
{
size_t packetsize;
while( m_nsend < m_maxPacketSize)
{
m_nsend++;
m_icmp_seq++;
packetsize = packIcmp(m_icmp_seq, (struct icmp*)m_sendpacket); /*设置ICMP报头*/
if(sendto(m_sockfd,m_sendpacket, packetsize, 0, (struct sockaddr *) &m_dest_addr, sizeof(m_dest_addr)) < 0 )
{
perror("sendto error");
continue;
}
}
return true;
}
/*接收所有ICMP报文*/
bool Ping::recvPacket(PingResult &pingResult)
{
int len;
extern int errno;
struct IcmpEchoReply icmpEchoReply;
int maxfds = m_sockfd + 1;
int nfd = 0;
fd_set rset;
FD_ZERO(&rset);
socklen_t fromlen = sizeof(m_from_addr);
struct timeval timeout;
timeout.tv_sec = 4;
timeout.tv_usec = 0;
for (int recvCount = 0; recvCount < m_maxPacketSize; recvCount++)
{
//printf("begin recv\n");
FD_SET(m_sockfd, &rset);
if ((nfd = select(maxfds, &rset, NULL, NULL, &timeout)) == -1) {
perror("select error");
continue;
}
if (nfd == 0) {
//recv time out
//printf("request timeout\n");
icmpEchoReply.isReply = false;
pingResult.icmpEchoReplys.push_back(icmpEchoReply);
continue;
}
if (FD_ISSET(m_sockfd, &rset)) {
if( (len = recvfrom(m_sockfd, m_recvpacket,sizeof(m_recvpacket),0, (struct sockaddr *)&m_from_addr,&fromlen)) <0)
{
if(errno==EINTR)
continue;
perror("recvfrom error");
continue;
}
icmpEchoReply.fromAddr = inet_ntoa(m_from_addr.sin_addr) ;
if (icmpEchoReply.fromAddr != pingResult.ip) {
//printf("invalid address, discard\n");
//retry again
recvCount--;
continue;
}
}
if(unpackIcmp(m_recvpacket, len, &icmpEchoReply)==-1) {
//retry again
recvCount--;
continue;
}
icmpEchoReply.isReply = true;
pingResult.icmpEchoReplys.push_back(icmpEchoReply);
m_nreceived++;
}
return true;
}
bool Ping::getsockaddr(const char * hostOrIp, struct sockaddr_in* sockaddr) {
struct hostent *host;
struct sockaddr_in dest_addr;
unsigned long inaddr=0l;
bzero(&dest_addr,sizeof(dest_addr));
dest_addr.sin_family=AF_INET;
/*判断是主机名还是ip地址*/
if( inaddr=inet_addr(hostOrIp)==INADDR_NONE)
{
if((host=gethostbyname(hostOrIp))==NULL) /*是主机名*/
{
//printf("gethostbyname error:%s\n", hostOrIp);
return false;
}
memcpy( (char *)&dest_addr.sin_addr,host->h_addr,host->h_length);
}
/*是ip地址*/
else if (!inet_aton(hostOrIp, &dest_addr.sin_addr)){
//memcpy( (char *)&dest_addr,(char *)&inaddr,host->h_length);
//fprintf(stderr, "unknow host:%s\n", hostOrIp);
return false;
}
*sockaddr = dest_addr;
return true;
}
bool Ping::ping(std::string host, PingResult& pingResult) {
return ping(host, 1, pingResult);
}
bool Ping::ping(std::string host, int count, PingResult& pingResult) {
struct protoent *protocol;
int size = 50 * 1024;
IcmpEchoReply icmpEchoReply;
bool ret;
m_nsend = 0;
m_nreceived = 0;
pingResult.icmpEchoReplys.clear();
m_maxPacketSize = count;
m_pid = getpid();
pingResult.dataLen = m_datalen;
// if( (protocol = getprotobyname("icmp") )==NULL)
// {
// perror("getprotobyname");
// return false;
// }
/*生成使用ICMP的原始套接字,这种套接字只有root才能生成*/
// if( (m_sockfd=socket(AF_INET,SOCK_RAW,protocol->p_proto) )<0)
// {
// //perror("socket error");
// extern int errno;
// pingResult.error = strerror(errno);
// return false;
// }
if ((m_sockfd = socket(AF_INET, SOCK_RAW, IPPROTO_ICMP))<0)
{
perror("socket error");
}
/*扩大套接字接收缓冲区到50K这样做主要为了减小接收缓冲区溢出的
的可能性,若无意中ping一个广播地址或多播地址,将会引来大量应答*/
setsockopt(m_sockfd,SOL_SOCKET,SO_RCVBUF,&size,sizeof(size) );
/*获取main的进程id,用于设置ICMP的标志符*/
if (!getsockaddr(host.c_str(), &m_dest_addr)) {
pingResult.error = "unknow host " + host;
return false;
}
pingResult.ip = inet_ntoa(m_dest_addr.sin_addr);
sendPacket(); /*发送所有ICMP报文*/
recvPacket(pingResult); /*接收所有ICMP报文*/
pingResult.nsend = m_nsend;
pingResult.nreceived = m_nreceived;
close(m_sockfd);
return true;
}ping.h
#ifndef PING_H #define PING_H #include#include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #define PACKET_SIZE 4096 #define MAX_WAIT_TIME 5 #define MAX_NO_PACKETS 3 struct IcmpEchoReply { int icmpSeq; int icmpLen; int ipTtl; double rtt; std::string fromAddr; bool isReply; }; struct PingResult { int dataLen; int nsend; int nreceived; std::string ip; std::string error; std::vector icmpEchoReplys; }; class Ping { public: Ping(); bool ping(std::string host, PingResult &pingResult); bool ping(std::string host, int count, PingResult& pingResult); private: unsigned short getChksum(unsigned short *addr,int len); int packIcmp(int pack_no, struct icmp* icmp); bool unpackIcmp(char *buf,int len, struct IcmpEchoReply *icmpEchoReply); struct timeval tvSub(struct timeval timeval1,struct timeval timval2); bool getsockaddr(const char * hostOrIp, sockaddr_in* sockaddr); bool sendPacket(); bool recvPacket(PingResult &pingResult); private: char m_sendpacket[PACKET_SIZE]; char m_recvpacket[PACKET_SIZE]; int m_maxPacketSize; int m_sockfd; int m_datalen; int m_nsend; int m_nreceived; int m_icmp_seq; struct sockaddr_in m_dest_addr; struct sockaddr_in m_from_addr; pid_t m_pid; }; #endif
实例代码：
if ( eth == false )
{
char * hostOrIp = "192.168.1.20";
int nsend = 0, nreceived = 0;
bool ret;
PingResult pingResult;
Ping ping = Ping();
for (int count = 1; count <= 4; count++)
{
ret = ping.ping(hostOrIp, 1, pingResult);
if (count == 1)
{
printf("PING %s(%s): %d bytes data in ICMP packets.\n", hostOrIp, pingResult.ip.c_str(), pingResult.dataLen);
}
if (!ret)
{
printf("%s\n", pingResult.error.c_str());
break;
}
showPingResult(pingResult);
nsend += pingResult.nsend;
nreceived += pingResult.nreceived;
}
if (ret)
{
printf("%d packets transmitted, %d received , %%%d lost\n", nsend, nreceived,
(nsend - nreceived) / nsend * 100);
eth = true;
system("echo 0 > /sys/class/gpio/gpio230/value"); // 灯6
}
else
{
printf("-----------------eth0 failed--------------\n");
eth = false;
system("echo 1 > /sys/class/gpio/gpio230/value"); // 灯6
}
}