[Boost-users] weird boost::asio problems opening acceptor

Subject: [Boost-users] weird boost::asio problems opening acceptor
From: andrew.marlow_at_[hidden]
Date: 2010-10-05 05:55:45

I have a server where there must be only one instance of it for a given 
machine on a given port number. Here is the code I used to try to make 
that happen:

boost::asio::io_service ios;
boost::asio::ip::tcp::endpoint primaryEndpoint(boost::asio::ip::tcp::v4(), 
primaryPort);
std::auto_ptr<boost::asio::ip::tcp::acceptor> primaryAcceptor;

try
{
    primaryAcceptor.reset(new boost::asio::ip::tcp::acceptor(ios, 
primaryEndpoint));
    primaryAcceptor->open(primaryEndpoint.protocol());
 
primaryAcceptor->set_option(boost::asio::ip::tcp::acceptor::reuse_address(true));
    primaryAcceptor->bind(primaryEndpoint);
}
catch(std::exception& ex)
{
    std::cout << "Error: Cannot obtain port " << primaryPort 
                          << ", " << ex.what() << ", server must be 
already running." << std::endl;
}

It always prints the error. The error is 'Already open'. The exception 
gets thrown from the call to open. What am I doing wrong please? If don't 
do the open etc then I can run up a second instance and it will have the 
port also. It is as if SO_REUSEADDR is true. I always thought that 
SO_REUSEADDR was false by default. When I run it in the debugger and 
breakpoint before the call to open , the process has the port open for 
listening, as revealed by 'netstat -a'.  It is as if it has already done 
the open with SO_REUSEADDR set to true.

I am using boost version 1.42.0 on Windoze-XP compiled with Visual Studio 
2005 (don't laugh....).

Regards,

Andrew Marlow

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