尝试关闭SSL套接字时使用boost asio 1.64的分段错误（SIGSEGV）

Question

我不明白如何关闭boost::asio ssl套接字。 我已经尝试了几种方法，但是总会在某些时候出现Segmentation fault 。

我一直在阅读以下文章来解决这种情况： boost asio ssl async_shutdown总是以错误结束吗？

具体来说，我正在尝试实施

甲方发起shutdown（）并等待乙方以shutdown（）响应

请注意，客户端和服务器都在localhost中运行。

下面是客户端代码：

typedef boost::asio::ssl::stream<boost::asio::ip::tcp::socket> SSLSocket;

MyClass::MyClass(const std::string &url,
    const std::string &port) throw() :
    m_socket(NULL), m_url(url), m_port(port), m_isConnected(false)
{
}

void MyClass::disconnect()
{
  // See the section "the disconnect method"
}

bool MyClass::tryConnect() throw()
{ 
  boost::asio::io_service ioService;
  boost::asio::ssl::context ctx(boost::asio::ssl::context::sslv23);
  m_socket = new SSLSocket(ioService, ctx);

  tcp::resolver resolver(ioService);
  tcp::resolver::query query(m_url, m_port);

  tcp::resolver::iterator end;
  tcp::resolver::iterator endpoint_iterator = resolver.resolve(query);

  boost::system::error_code error = boost::asio::error::host_not_found;
  boost::asio::connect(m_socket->lowest_layer(), endpoint_iterator, error);

  if(endpoint_iterator == end || error)
  {
    m_isConnected = false;
  }
  else
  {
    m_socket->set_verify_mode(boost::asio::ssl::verify_none);
    m_socket->handshake(SSLSocket::client);

    m_isConnected = true;
  }

  return m_isConnected;
}

void MyClass::write(const std::string &message)
{
  boost::asio::write(*m_socket, boost::asio::buffer(message));
}

std::string MyClass::readUntil(const std::string &until)
{
  boost::asio::read_until(*m_socket, response, until);
  ...
  return response;
}

int main()
{
  MyClass mc(...);

  while(true)
  {
    bool connected = mc.isConnected();

    if(!connected)
    {
      connected = mc.tryConnect();
    }

    if(connected)
    {
      mc.send(...);
      std::string resp = mc.readUntil(...);
      mc.disconnect();
    }
  }
}

断开方法

我已阅读评论中链接的帖子，并且更新了ssl服务器和客户端。 现在，他们两个都执行shutdown()操作以正确关闭ssl连接，但是关闭套接字时我仍然出错。

我已经更新了disconnect()方法（它总是在程序崩溃的地方），如下所示：

...
boost::asio::ssl::stream<boost::asio::ip::tcp::socket> *m_socket;
...
void MyClass::disconnect()
{
  // Shutdown the connection
  // TODO is this the correct way to close a boost asio socket?
  if(m_socket != NULL)
  {
    std::cout << "shutting down the socket, thread = " <<
        pthread_self() << std::endl;

    // I have checked that the thread is always the same, so the problem 
    // is not related with race conditions or similar.

    boost::system::error_code ec;
    m_socket->lowest_layer().shutdown(
        boost::asio::ip::tcp::socket::shutdown_both, ec);

    std::cout <<
        "Shut down, err = " << ec << ", " <<
        "Category: " << ec.category().name() << std::endl;

    if(!ec)
    {
      std::cout << "closing the socket, thread = " <<
         pthread_self() << std::endl;

      if(m_socket->lowest_layer().is_open())
      {
        m_socket->lowest_layer().close(ec);
      }

      std::cout <<
        "Socket closed, err = " << ec << ", " <<  "Category: " <<
        ec.category().name() << std::endl;

      if(!ec)
      {
        std::cout << "Deleting socket... " << std::endl;
        delete m_socket;
        m_socket = NULL;
        std::cout << "Socket deleted" << std::endl;
      }
    }
  }

  m_isConnected = false;
}

错误回溯

bkactrace（来自断开连接方法）在这里：

#0  0x4158114f in boost::system::error_code::operator=<boost::asio::error::basic_errors> (this=0x1d, val=boost::asio::error::operation_aborted)
    at .../include/boost/system/error_code.hpp:344
#1  0x41587308 in boost::asio::detail::epoll_reactor::deregister_descriptor (this=0x46463045, descriptor=27, descriptor_data=@0x812ef14: 0x8151ea8, 
    closing=true) at .../include/boost/asio/detail/impl/epoll_reactor.ipp:351
#2  0x41588550 in boost::asio::detail::reactive_socket_service_base::close (this=0x812efbc, impl=..., ec=...)
    at .../include/boost/asio/detail/impl/reactive_socket_service_base.ipp:104
#3  0x415885da in boost::asio::stream_socket_service<boost::asio::ip::tcp>::close (this=0x812efa8, impl=..., ec=...)
    at .../include/boost/asio/stream_socket_service.hpp:174
#4  0x41588630 in boost::asio::basic_socket<boost::asio::ip::tcp, boost::asio::stream_socket_service<boost::asio::ip::tcp> >::close (this=0x812ef08, ec=...)
    at .../include/boost/asio/basic_socket.hpp:385
#5  0x41576383 in MyClass::disconnect (this=0x80a6f58) at ...

检查frame 1 ，可以看出boost正在产生的错误是boost::asio::error::operation_aborted;

另外，使用gdb和simetimes运行进程时，我看到以下断言失败 ：

pthread_mutex_lock.c:312: __pthread_mutex_lock_full: Assertion `(-(e)) != 3 || !robust' failed.

Answer 1

我发现了问题。

我正在用以下方法打开套接字：

void connect()
{
  ...
  boost::asio::io_service m_ioService
  ...
  m_sock = new SSLSocket(m_ioService, ...)
}

当connect方法返回时， m_ioService不在范围内，因此由于ioService被删除，套接字崩溃。 注意， m_ioService是通过引用传递的，此外，它是不可复制的。