使用boost :: ASIO是有一个可移植的方式，找出空闲的端口号 [英] Using boost::asio is there a portable way to find out free port number

问题描述

目前，我正在试图找出一种方法来找到一个免费的端口号来建立连接，最好用的boost :: ASIO。那么这个端口号将用于监听（只有这样我可以打开一个套接字）。

I'm currently trying to figure out a way to find the number of a free port to establish a connection, ideally with boost::asio. This port number would then be used to listen on (and only then can I open a socket).

粗略地说，有没有办法做到

Roughly, is there a way to do

   tcp::resolver::query query("localhost", port); 

其中端口留空（将其设置为0不工作）

where the port is left blank (setting it to 0 doesn't work)

的看到previously的选项没有一个是便携式的，或有效率。

None of the options seen previously were portable, or efficient.

推荐答案

来处理这只是让操作系统随机选择一个可用的端口，此刻，该插座被绑定到一个端口的最好方法。告诉套接字绑定到端口0，然后查询套接字其绑定到如果成功的实际端口。不要试图找到一个端口的时间提前，然后绑定到它，引入了竞争条件。另一个插座可以捡的端口，你发现后，但在此之前，你可以绑定。

The best way to handle this is to just let the OS pick a random available port at the moment that the socket is being bound to a port. Tell the socket to bind to port 0, then query the socket for the actual port it bound to if successful. Do not try to find a port ahead of time and then bind to it, that introduces a race condition. Another socket could snag the port after you found it but before you could bind it.

这篇关于使用boost :: ASIO是有一个可移植的方式，找出空闲的端口号的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！