在 linux 下用 C++ ping 的最佳方法是什么？
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What is the best method to ping in c++ under linux?
提问by nios
I have to call ping from c++ code.I'd like to easily read the output for further utilizations.
我必须从 C++ 代码调用 ping。我想轻松读取输出以供进一步利用。
I have come up with two solutions:
我想出了两个解决方案：
- use a fork and a pipe, redirect ping output to the pipe and then parse it
- find a library suited for the purpose to use a ping(ip_addresss) function directly
- 使用叉子和管道，将 ping 输出重定向到管道，然后解析它
- 找到适合直接使用 ping(ip_addresss) 函数的库
I'd like the latter but i didn't find anything that was clearly a standard solution.
我想要后者，但我没有找到任何明显是标准解决方案的东西。
How would you do it ?
你会怎么做？
采纳答案by e.James
I would go with your first option. Linux is built around the concept of having small, specialized apps which do one thing really well, communicating with pipes. Your app shouldn't include a library to implement ping, since there is already a built-in command to do it, and it works very well!
我会选择你的第一个选择。Linux 是围绕拥有小型、专门的应用程序的概念而构建的，这些应用程序可以很好地完成一件事，即通过管道进行通信。您的应用程序不应包含用于实现 ping 的库，因为已经有一个内置命令可以执行此操作，而且效果很好！
回答by Nicola Bonelli
From the educational point of view invoking an external binary is very inadvisable. Especially for a simple task such as sending an ICMP echo request, you should learn a bit of socket.
从教育的角度来看，调用外部二进制文件是非常不可取的。特别是对于发送ICMP echo请求这样的简单任务，你应该学习一点socket。
回答by omeraygor
#include <fcntl.h>
#include <errno.h>
#include <sys/socket.h>
#include <resolv.h>
#include <netdb.h>
#include <netinet/in.h>
#include <netinet/ip_icmp.h>
#define PACKETSIZE 64
struct packet
{
struct icmphdr hdr;
char msg[PACKETSIZE-sizeof(struct icmphdr)];
};
int pid=-1;
struct protoent *proto=NULL;
int cnt=1;
/*--------------------------------------------------------------------*/
/*--- checksum - standard 1s complement checksum ---*/
/*--------------------------------------------------------------------*/
unsigned short checksum(void *b, int len)
{
unsigned short *buf = b;
unsigned int sum=0;
unsigned short result;
for ( sum = 0; len > 1; len -= 2 )
sum += *buf++;
if ( len == 1 )
sum += *(unsigned char*)buf;
sum = (sum >> 16) + (sum & 0xFFFF);
sum += (sum >> 16);
result = ~sum;
return result;
}
/*--------------------------------------------------------------------*/
/*--- ping - Create message and send it. ---*/
/* return 0 is ping Ok, return 1 is ping not OK. ---*/
/*--------------------------------------------------------------------*/
int ping(char *adress)
{
const int val=255;
int i, sd;
struct packet pckt;
struct sockaddr_in r_addr;
int loop;
struct hostent *hname;
struct sockaddr_in addr_ping,*addr;
pid = getpid();
proto = getprotobyname("ICMP");
hname = gethostbyname(adress);
bzero(&addr_ping, sizeof(addr_ping));
addr_ping.sin_family = hname->h_addrtype;
addr_ping.sin_port = 0;
addr_ping.sin_addr.s_addr = *(long*)hname->h_addr;
addr = &addr_ping;
sd = socket(PF_INET, SOCK_RAW, proto->p_proto);
if ( sd < 0 )
{
perror("socket");
return 1;
}
if ( setsockopt(sd, SOL_IP, IP_TTL, &val, sizeof(val)) != 0)
{
perror("Set TTL option");
return 1;
}
if ( fcntl(sd, F_SETFL, O_NONBLOCK) != 0 )
{
perror("Request nonblocking I/O");
return 1;
}
for (loop=0;loop < 10; loop++)
{
int len=sizeof(r_addr);
if ( recvfrom(sd, &pckt, sizeof(pckt), 0, (struct sockaddr*)&r_addr, &len) > 0 )
{
return 0;
}
bzero(&pckt, sizeof(pckt));
pckt.hdr.type = ICMP_ECHO;
pckt.hdr.un.echo.id = pid;
for ( i = 0; i < sizeof(pckt.msg)-1; i++ )
pckt.msg[i] = i+'0';
pckt.msg[i] = 0;
pckt.hdr.un.echo.sequence = cnt++;
pckt.hdr.checksum = checksum(&pckt, sizeof(pckt));
if ( sendto(sd, &pckt, sizeof(pckt), 0, (struct sockaddr*)addr, sizeof(*addr)) <= 0 )
perror("sendto");
usleep(300000);
}
return 1;
}
/*--------------------------------------------------------------------*/
/*--- main - look up host and start ping processes. ---*/
/*--------------------------------------------------------------------*/
int main(int argc, char *argv[])
{
if (ping("www.google.com"))
printf("Ping is not OK. \n");
else
printf("Ping is OK. \n");
return 0;
}
回答by orip
Check out BusyBox's source for 'ping'- you can use the ping4and ping6functions. Just be mindful of the GPL.
查看 BusyBox 的'ping' 源代码- 您可以使用ping4和ping6函数。请注意 GPL。
Spawning 'ping' should work too - check out popen(2)for a simpler API that also runs a shell. If it's a problem, pipe+ fork+ execshould work.
生成 'ping' 也应该工作 - 查看popen(2)一个更简单的 API，它也运行一个 shell。如果这是一个问题，pipe+ fork+exec应该工作。
回答by nios
I've managed to do like this:
我设法这样做：
I use popen which basically creates a pipe, fork and exec Then, if I need, i can wait with pclose.
我使用 popen，它基本上创建了一个管道、fork 和 exec 然后，如果我需要，我可以用 pclose 等待。
