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[英]program crash with boost::asio::spawn and socket::async_receive_from
[英]boost::asio, why does my socket immediately run callback function after calling async_receive_from?
我正在尝试使用3种方式进行握手建立异步连接。 在代码的底部,有一个main方法,该方法接受一个参数来确定它是充当客户端还是服务器。
如果它充当服务器,它会创建一个套接字,并等待它接收数据,然后调用回调函数multiplex
找出如何处理接收到的数据。
如果它充当客户端,我还将创建一个套接字,该套接字异步等待接收数据,但也会使用create_connection
方法通过udp将syn数据包发送到服务器。
在Socket的构造函数中,我执行start_receive
方法,该方法应在udp套接字上调用async_receive_from
。 问题在于它立即使用端点0.0.0.0:0调用回调函数multiplex
,而不仅仅是等待接收数据。
#include <iostream>
#include <string>
#include <boost/asio.hpp>
#include <boost/shared_ptr.hpp>
#include <boost/cstdint.hpp>
#include <boost/function.hpp>
#include <boost/bind.hpp>
#include <unordered_map>
#include "packed_message.h"
#include "segment.pb.h"
#include "rtp.hpp"
#define DEBUG true
#define BUFFER_SIZE 10000
using boost::asio::ip::udp;
typedef boost::shared_ptr<rtp::Segment> SegmentPtr;
typedef std::vector<uint8_t> data_buffer;
// constructor for socket
rtp::Socket::Socket(boost::asio::io_service& io_service_, std::string source_ip, std::string source_port):
io_service_(io_service_),
socket_(io_service_, udp::endpoint(boost::asio::ip::address::from_string(source_ip), std::stoi(source_port))),
source_port(source_port),
source_ip(source_ip)
{
// accept incoming rtp segments
std::cout << rtp::get_endpoint_str(socket_.local_endpoint()) << std::endl;
start_receive();
}
/**
* Accept incoming rtp segments
*/
void rtp::Socket::start_receive()
{
data_buffer tmp_buf;
socket_.async_receive_from(boost::asio::buffer(tmp_buf), remote_endpoint_,
boost::bind(&rtp::Socket::multiplex, this,
tmp_buf,
boost::asio::placeholders::error,
boost::asio::placeholders::bytes_transferred));
}
void rtp::Socket::multiplex(data_buffer& tmp_buf,
const boost::system::error_code& error,
std::size_t /*bytes_transferred*/)
{
std::string identifier = rtp::get_endpoint_str(remote_endpoint_);
if (connections.count(identifier) == 0 )
{
boost::shared_ptr<Connection> connection(new Connection(remote_endpoint_));
connections.insert({rtp::get_endpoint_str(remote_endpoint_), connection});
std::cout << rtp::get_endpoint_str(remote_endpoint_) << std::endl;
connection_establishment(tmp_buf, connections.at(identifier));
}
else if(!(connections.at(identifier)->is_valid())) // connection not in list of connections
{
connection_establishment(tmp_buf, connections.at(identifier));
}
boost::shared_ptr<rtp::Connection> rtp::Socket::create_connection(std::string ip, std::string port)
{
udp::resolver resolver_(io_service_);
udp::resolver::query query_(ip, port);
udp::endpoint remote_endpoint_ = *resolver_.resolve(query_);
boost::shared_ptr<Connection> connection(new Connection(remote_endpoint_));
connections.insert({rtp::get_endpoint_str(remote_endpoint_), connection});
PackedMessage<rtp::Segment> m_packed_segment(SegmentPtr(new rtp::Segment()));
boost::shared_ptr<data_buffer> message(new data_buffer);
SegmentPtr ackseg(new rtp::Segment());
ackseg->set_ack(true);
PackedMessage<rtp::Segment> initialack(ackseg);
initialack.pack(*message);
socket_.async_send_to(boost::asio::buffer(*message), remote_endpoint_,
boost::bind(&rtp::Socket::handle_send, this, message,
boost::asio::placeholders::error,
boost::asio::placeholders::bytes_transferred));
return connection;
}
void rtp::Socket::connection_establishment(data_buffer& m_readbuf, boost::shared_ptr<Connection> connection)
{
int buffer_position(0);
PackedMessage<rtp::Segment> m_packed_segment(boost::shared_ptr<rtp::Segment>(new rtp::Segment()));
boost::shared_ptr<data_buffer> message(new data_buffer);
unsigned msg_len = m_packed_segment.decode_header(m_readbuf, buffer_position);
buffer_position += HEADER_SIZE;
m_packed_segment.unpack(m_readbuf, msg_len, buffer_position);
buffer_position += msg_len;
SegmentPtr synackseg = m_packed_segment.get_msg();
if (synackseg->syn() && synackseg->ack())
{
SegmentPtr ackseg(new rtp::Segment());
ackseg->set_ack(true);
PackedMessage<rtp::Segment> finalack(ackseg);
finalack.pack(*message);
connection->set_valid(true);
socket_.async_send_to(boost::asio::buffer(*message), remote_endpoint_,
boost::bind(&rtp::Socket::handle_send, this,
message,
boost::asio::placeholders::error,
boost::asio::placeholders::bytes_transferred));
}
else if (synackseg->syn() )
{
SegmentPtr synackseg(new rtp::Segment());
synackseg->set_ack(true);
synackseg->set_syn(true);
PackedMessage<rtp::Segment> synack(synackseg);
synack.pack(*message);
socket_.async_send_to(boost::asio::buffer(*message), remote_endpoint_,
boost::bind(&rtp::Socket::handle_send, this,
message,
boost::asio::placeholders::error,
boost::asio::placeholders::bytes_transferred));
}
else if (synackseg->ack())
{
connection->set_valid(true);
}
start_receive();
}
void rtp::Socket::handle_send(boost::shared_ptr<data_buffer> /*message*/,
const boost::system::error_code& /*error*/,
std::size_t /*bytes_transferred*/)
{
}
/**
* Get remote peer ip and port in string "<ip>:<port>"
*/
std::string rtp::get_endpoint_str(udp::endpoint remote_endpoint_)
{
std::string ip = remote_endpoint_.address().to_string();
std::string port = std::to_string(remote_endpoint_.port());
return ip + ":" + port;
}
rtp::Connection::Connection(udp::endpoint remote_endpoint_):
remote_endpoint_(remote_endpoint_),
dest_ip(remote_endpoint_.address().to_string()),
dest_port(std::to_string(remote_endpoint_.port())),
valid(false)
{
}
bool rtp::Connection::is_valid()
{
return valid;
}
void rtp::Connection::set_valid(bool val)
{
if(DEBUG) std::cerr << "Connection Created" << std::endl;
valid = val;
}
int main(int argc, char* argv[])
{
if (argc == 1)
{
std::cerr << "Not enough args" << std::endl;
return 1;
}
boost::asio::io_service io_service_;
if (std::string(argv[1]) == u8"server")
{
rtp::Socket socket(io_service_, u8"127.0.0.1", u8"4545");
}
else if (std::string(argv[1]) == u8"client")
{
rtp::Socket socket(io_service_, u8"127.0.0.1", u8"4546");
socket.create_connection(u8"127.0.0.1", u8"4545");
}
io_service_.run();
return 0;
}
问题很可能是这些行:
if (std::string(argv[1]) == u8"server")
{
rtp::Socket socket(io_service_, u8"127.0.0.1", u8"4545");
}
else if (std::string(argv[1]) == u8"client")
{
rtp::Socket socket(io_service_, u8"127.0.0.1", u8"4546");
socket.create_connection(u8"127.0.0.1", u8"4545");
}
在每个if
语句主体中,您都声明了一个变量socket
,但这仅在if
语句主体的范围内是局部的。 一旦作用域结束,变量将被销毁并且不再存在。
您看到的行为可能与该问题有关,即您在这些范围内创建的对象被破坏了。
您需要创建一个套接字,其寿命比任何内部作用域都要长,并且该套接字将持续到io_service_.run()
返回。
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