SegFault on imap connections with timeout

[alex-aparin]

Hello. I have encountered occasional segfault related with send_async method. It's seems like there is case of inproper canceling async_write operation by timeout. Suspicious code

I suppose in the case of timeout async_write operation should be canceled explicitly, otherwise dialog_error exception raised from wait_async will clean stack and buffer will point to corrupted memory.

I have changed locally wait_async function which solved problem

    void dialog::wait_async(const bool& has_op, const bool& op_error, const char* expired_msg, const char* op_msg, const error_code& error)
    {
        do
        {
            if (timer_expired_)
            {
                socket_->cancel();                      // cancel the pending async op
                while (!has_op && !op_error)            // drain its completion handler
                    ios_.run_one();                     // (fires with operation_aborted)
                throw dialog_error(expired_msg, error.message());
            }
            if (op_error)
                throw dialog_error(op_msg, error.message());
            ios_.run_one();
        }
        while (!has_op);
    }

It's no so good solution, but I hope it better highlights the issue

[karastojko]

Hi,
Thank you for the report. Does it mean that the following test occasionally crashes without your fix:

BOOST_AUTO_TEST_CASE(connect_with_timeout_yahoo)
{
    auto start = std::chrono::steady_clock::now();
    BOOST_CHECK_THROW(imap("server.com", 993, std::chrono::milliseconds(10)), dialog_error);
    auto end = std::chrono::steady_clock::now();
    std::chrono::duration<double> elapsed = end - start;
    // Check that no more than 50 milliseconds has elapsed.
    BOOST_CHECK(elapsed.count() < 0.05);
}

If I use it with the valid server hostname (so that the address is resolved), the test passes.

[mr-j0nes]

PR #224 solves this too.