【发布时间】：2016-05-03 12:18:55
【问题描述】：
我已经修改了示例http://www.boost.org/doc/libs/1_51_0/doc/html/boost_asio/example/icmp/ping.cpp 关于如何定期 ping 主机以同时 ping 多台主机。 首先，创建所有主机的请求并将其发送到套接字。然后在第二阶段收集所有响应，直到计时器到期。
3 个客户端的修改示例：
// Headers from ping example:
// http://www.boost.org/doc/libs/1_51_0/doc/html/boost_asio/example/icmp/
#include "icmp_header.hpp"
#include "ipv4_header.hpp"
#include <boost/asio.hpp>
#include <iostream>
using boost::asio::ip::icmp;
using boost::asio::deadline_timer;
using boost::asio::io_service;
using boost::asio::streambuf;
using boost::system::error_code;
using std::cout;
using std::endl;
namespace posix_time = boost::posix_time;
static const std::string BODY = "ping";
static const auto PROCESS = GetCurrentProcessId();
static int gSequence;
static io_service gService;
static icmp::socket gSocket(gService, icmp::v4());
static deadline_timer gTimer(gService);
static streambuf gReply;
static icmp::endpoint gReceiver;
void StartReceive()
{
gSocket.async_receive_from(gReply.prepare(65536), gReceiver,
[&](const error_code& error, size_t length)
{
gReply.commit(length);
ipv4_header ipv4Hdr;
icmp_header icmpHdr;
std::string body(BODY.size(), 0);
std::istream is(&gReply);
is >> ipv4Hdr >> icmpHdr;
is.read(&body[0], BODY.size());
auto ip = ipv4Hdr.source_address().to_string();
auto rc = gReceiver.address().to_string();
auto id = icmpHdr.identifier();
auto process = PROCESS;
auto sn = icmpHdr.sequence_number();
auto type = icmpHdr.type();
cout << " Length = " << length << endl;
cout << " Error = " << error << endl;
cout << " IP checksum = " << ipv4Hdr.header_checksum() << endl;
cout << " IP address = " << ip << endl;
cout << " Receiver address = " << rc << endl;
cout << " ICMP identification = " << id << endl;
cout << " ICMP type = " << (int)type << endl;
cout << " Process = " << process << endl;
cout << " Sequence = " << sn << endl;
if (is
&& icmpHdr.type() == icmp_header::echo_reply
&& icmpHdr.identifier() == PROCESS
&& icmpHdr.sequence_number() == gSequence
&& body == BODY)
{
cout << " > " << ip << endl;
}
cout << endl;
gReply.consume(length);
StartReceive();
});
}
int main()
{
icmp::resolver resolver(gService);
icmp_header echoRequest;
echoRequest.type(icmp_header::echo_request);
echoRequest.identifier(PROCESS);
for (gSequence = 0; gSequence < 3; ++gSequence)
{
cout << "----------------------------------------------------------" << endl;
cout << "Iteration = " << gSequence << endl;
cout << "----------------------------------------------------------" << endl;
echoRequest.sequence_number(gSequence);
compute_checksum(echoRequest, BODY.begin(), BODY.end());
streambuf request;
std::ostream os(&request);
os << echoRequest << BODY;
gService.reset();
StartReceive();
std::vector<std::string> pool
{
"10.170.110.29",
"10.170.97.39",
"10.170.7.52"
};
for (const auto & ip : pool)
{
icmp::resolver::query query(icmp::v4(), ip, "");
auto dest = *resolver.resolve(query);
gSocket.send_to(request.data(), dest);
}
gTimer.expires_from_now(posix_time::millisec(2000));
gTimer.async_wait([&](const error_code& error) { gService.stop(); });
gService.run();
gReply.commit(gReply.size());
gReply.consume(gReply.size());
}
return 0;
}
第一次迭代 (0) 每次都按预期工作，尽管接收到的第一个数据包的长度始终为零。但是，在所有后续迭代中，来自一个或多个客户端的响应不会被传递，而是来自另一个客户端的响应被传递多次。使用 Wireshark，我可以看到示例中的所有主机都非常迅速地对请求发送了一个响应。
这是产生的输出之一：
----------------------------------------------------------
Iteration = 0
----------------------------------------------------------
Length = 0
Error = system:10022
IP checksum = 0
IP address = 0.0.0.0
Receiver address = 0.0.0.0
ICMP identification = 0
ICMP type = 0
Process = 20464
Sequence = 0
Length = 32
Error = system:0
IP checksum = 595
IP address = 10.170.97.39
Receiver address = 10.170.97.39
ICMP identification = 20464
ICMP type = 0
Process = 20464
Sequence = 0
> 10.170.97.39
Length = 32
Error = system:0
IP checksum = 31034
IP address = 10.170.110.29
Receiver address = 10.170.110.29
ICMP identification = 20464
ICMP type = 0
Process = 20464
Sequence = 0
> 10.170.110.29
Length = 32
Error = system:0
IP checksum = 51432
IP address = 10.170.7.52
Receiver address = 10.170.7.52
ICMP identification = 20464
ICMP type = 0
Process = 20464
Sequence = 0
> 10.170.7.52
----------------------------------------------------------
Iteration = 1
----------------------------------------------------------
Length = 32
Error = system:0
IP checksum = 594
IP address = 10.170.97.39
Receiver address = 10.170.97.39
ICMP identification = 20464
ICMP type = 0
Process = 20464
Sequence = 1
> 10.170.97.39
Length = 32
Error = system:0
IP checksum = 51419
IP address = 10.170.7.52
Receiver address = 10.170.7.52
ICMP identification = 20464
ICMP type = 0
Process = 20464
Sequence = 1
> 10.170.7.52
Length = 32
Error = system:0
IP checksum = 51419
IP address = 10.170.7.52
Receiver address = 10.170.7.52
ICMP identification = 20464
ICMP type = 0
Process = 20464
Sequence = 1
> 10.170.7.52
----------------------------------------------------------
Iteration = 2
----------------------------------------------------------
Length = 32
Error = system:0
IP checksum = 593
IP address = 10.170.97.39
Receiver address = 10.170.97.39
ICMP identification = 20464
ICMP type = 0
Process = 20464
Sequence = 2
> 10.170.97.39
Length = 32
Error = system:0
IP checksum = 51407
IP address = 10.170.7.52
Receiver address = 10.170.7.52
ICMP identification = 20464
ICMP type = 0
Process = 20464
Sequence = 2
> 10.170.7.52
Length = 32
Error = system:0
IP checksum = 51407
IP address = 10.170.7.52
Receiver address = 10.170.7.52
ICMP identification = 20464
ICMP type = 0
Process = 20464
Sequence = 2
> 10.170.7.52
这是 Boost.Asio 的正确用法和行为吗？
谢谢
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标签： c++ boost boost-asio icmp