Hello,
I'm writing a middleware which basically adds an SSL layer to the connection between a client and a server. The connection is bidirectional, so I need to read from each side and write to the other. The client can also close the connection at any time, in which case async_shutdown() must be called on the server's stream.
The problem is, often the shutdown happens when the program is waiting on the server through async_read_some(), and the shutdown will never finish.
The following code illustrates this issue:
#include <iostream>
#include
#include
int main(int argc, char* argv[])
{
try
{
boost::asio::io_context io_context;
boost::asio::streambuf buffer;
boost::asio::ssl::context ctx(boost::asio::ssl::context::tlsv12);
ctx.set_verify_mode(boost::asio::ssl::verify_none);
boost::asio::ssl::streamboost::asio::ip::tcp::socket
sock(io_context, ctx);
sock.next_layer().connect(boost::asio::ip::tcp::endpoint(
boost::asio::ip::make_address("127.0.0.1"), 4433));
sock.handshake(boost::asio::ssl::stream_base::client);
/* "async_shutdown" won't appear unless async_read_some()
* is commented out */
sock.async_read_some(buffer.prepare(1024),
[](boost::system::error_code, size_t)
{std::cout << "async_read_some" << std::endl;});
sock.async_shutdown([](boost::system::error_code)
{std::cout << "async_shutdown" << std::endl;});
io_context.run();
}
catch (std::exception& e)
{
std::cerr << "Exception: " << e.what() << "\n";
}
return 0;
}
To reproduce, start up an SSL server:
openssl genrsa -out key.pem 2048
openssl req -new -sha256 -key key.pem -out csr.csr
openssl req -x509 -sha256 -days 365 -key key.pem -in csr.csr -out server.pem
openssl s_server -key key.pem -cert server.pem
and run the program. Notice that "async_shutdown" does not finish even if the server is killed.
In practice, this leaks the memory of the shutdown handler and whatever is bound to it. The only solution I can think of would be to cancel the read operation, but there's no portable way in asio to do this.
Can someone point out how to solve this?
Cheers,
Alexander
