我有一个需要不断ping设备的程序
然而，这个ping函数在1020次尝试后完全失败
int ping(string target)
{
int s, i, cc, packlen, datalen = DEFDATALEN;
struct hostent *hp;
struct sockaddr_in to, from;
//struct protoent *proto;
struct ip *ip;
u_char *packet, outpack[MAXPACKET];
char hnamebuf[MAXHOSTNAMELEN];
string hostname;
struct icmp *icp;
int ret, fromlen, hlen;
fd_set rfds;
struct timeval tv;
int retval;
struct timeval start, end;
int /*start_t, */end_t;
bool cont = true;
to.sin_family = AF_INET;
// try to convert as dotted decimal address, else if that fails assume it's a hostname
to.sin_addr.s_addr = inet_addr(target.c_str());
if (to.sin_addr.s_addr != (u_int)-1)
hostname = target;
else
{
hp = gethostbyname(target.c_str());
if (!hp)
{
cerr << "unknown host "<< target << endl;
return -1;
}
to.sin_family = hp->h_addrtype;
bcopy(hp->h_addr, (caddr_t)&to.sin_addr, hp->h_length);
strncpy(hnamebuf, hp->h_name, sizeof(hnamebuf) - 1);
hostname = hnamebuf;
}
packlen = datalen + MAXIPLEN + MAXICMPLEN;
if ( (packet = (u_char *)malloc((u_int)packlen)) == NULL)
{
cerr << "malloc error\n";
return -1;
}
/*
if ( (proto = getprotobyname("icmp")) == NULL)
{
cerr << "unknown protocol icmp" << endl;
return -1;
}
*/
if ( (s = socket(AF_INET, SOCK_RAW, IPPROTO_ICMP)) < 0)
{
perror("socket"); /* probably not running as superuser */
return -1;
}
icp = (struct icmp *)outpack;
icp->icmp_type = ICMP_ECHO;
icp->icmp_code = 0;
icp->icmp_cksum = 0;
icp->icmp_seq = 12345; /* seq and id must be reflected */
icp->icmp_id = getpid();
cc = datalen + ICMP_MINLEN;
icp->icmp_cksum = in_cksum((unsigned short *)icp,cc);
gettimeofday(&start, NULL);
i = sendto(s, (char *)outpack, cc, 0, (struct sockaddr*)&to, (socklen_t)sizeof(struct sockaddr_in));
if (i < 0 || i != cc)
{
if (i < 0)
perror("sendto error");
cout << "wrote " << hostname << " " << cc << " chars, ret= " << i << endl;
}
// Watch stdin (fd 0) to see when it has input.
FD_ZERO(&rfds);
FD_SET(s, &rfds);
// Wait up to one seconds.
tv.tv_sec = 1;
tv.tv_usec = 0;
while(cont)
{
retval = select(s+1, &rfds, NULL, NULL, &tv);
if (retval == -1)
{
perror("select()");
return -1;
}
else if (retval)
{
fromlen = sizeof(sockaddr_in);
if ( (ret = recvfrom(s, (char *)packet, packlen, 0,(struct sockaddr *)&from, (socklen_t*)&fromlen)) < 0)
{
perror("recvfrom error");
return -1;
}
// Check the IP header
ip = (struct ip *)((char*)packet);
hlen = sizeof( struct ip );
if (ret < (hlen + ICMP_MINLEN))
{
cerr << "packet too short (" << ret << " bytes) from " << hostname << endl;;
return -1;
}
// Now the ICMP part
icp = (struct icmp *)(packet + hlen);
if (icp->icmp_type == ICMP_ECHOREPLY)
{
cout << "Recv: echo reply"<< endl;
if (icp->icmp_seq != 12345)
{
cout << "received sequence # " << icp->icmp_seq << endl;
continue;
}
if (icp->icmp_id != getpid())
{
cout << "received id " << icp->icmp_id << endl;
continue;
}
cont = false;
}
else
{
cout << "Recv: not an echo reply" << endl;
continue;
}
gettimeofday(&end, NULL);
end_t = 1000000*(end.tv_sec - start.tv_sec) + (end.tv_usec - start.tv_usec);
if(end_t < 1)
end_t = 1;
cout << "Elapsed time = " << end_t << " usec" << endl;
return end_t;
}
else
{
cout << "No data within one seconds.\n";
return 0;
}
}
return 0;
}
如果我运行两次ping函数，它会在正好一半的510处失败。而且模式是准确的。这是1020标记后的输出
socket: Too many open files
ping returned -1
我在网络编程方面非常糟糕，但我甚至不知道上面的代码从哪里开始。
我错过了某个地方吗？
ping函数取自：http://www.linuxforums.org/forum/networking/60389-implementing-ping-c.html
编辑：在Fedora 13上运行Ubuntu 10.10，同样的问题
由于