CODEWITHSUNDEEP
c++socketssslboostboost-asio
Ælex
Ælex

Reputation: 14839

boost asio SSL server error: called a function you should not call

I am using the example from boost with three minor differences:

  1. I use threads to process io_service
  2. I have limited the protocol to > TLS v1.1
  3. There is no password callback, because the cert key has no password

The threads simply process various connections in parallel

void server::start()
{
    for (std::size_t i = 0; i < thread_pool_size_; i++) {
        threads_.push_back(std::thread([&]() {
            io_service_.run();
        }));
    }
    for (auto & t : threads_) { 
        t.join();
    }
}

The context arguments are:

ctx.set_options(boost::asio::ssl::context::default_workarounds
               |boost::asio::ssl::context::no_sslv2
               |boost::asio::ssl::context::no_sslv3
               |boost::asio::ssl::context::no_tlsv1
               |boost::asio::ssl::context::no_tlsv1_1
               |boost::asio::ssl::context::single_dh_use);

Apart from that, a connection class controls internally a ssl_socket, which follows the following callback chain:

ctor -> start -> async_handshake -> read_header -> async_read_until -> process_header ...

If I replace the SSL socket with a plaintext socket ip::tcp::socket then everything works fine. When using the SSL socket, I keep getting called a function you should not call.

GDB shows that this originates from async_handshake. After reading this SO post I managed to obtain the error code:

(20,197,66) error:140C5042:SSL routines:ssl_undefined_function:called a function you should not call.

I'm using Boost 1.58 on Ubuntu 16.04. Any help as to why this is happening, what might be causing it, or what I could possibly have done wrong?

If it matters, I am testing with curl using the -insecure flag.

EDIT

Did try without the restrictive protocol flags, and by setting a password callback - problem still persists.

Upvotes: 1

Views: 1762

Answers (1)

&#198;lex
&#198;lex

Reputation: 14839

Seems that the following line triggers the problem:

context_(io_service, boost::asio::ssl::context::tlsv12_client)

I should have paid more attention to my code (copy-paste is the root of all evil): The offending line was in the context constructor:

ctx_(io_service, boost::asio::ssl::context::tlsv12_client)

I've replaced with the server version:

context_(io_service, boost::asio::ssl::context::tlsv12_server)

The full list is hidden in the implementation header of boost. Insert big facepalm here :-)

Upvotes: 4

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