libzmq/src/curve_client.cpp

/* SPDX-License-Identifier: MPL-2.0 */

#include "precompiled.hpp"
#include "macros.hpp"

#ifdef ZMQ_HAVE_CURVE

#include "msg.hpp"
#include "session_base.hpp"
#include "err.hpp"
#include "curve_client.hpp"
#include "wire.hpp"
#include "curve_client_tools.hpp"
#include "secure_allocator.hpp"

zmq::curve_client_t::curve_client_t (session_base_t *session_,
                                     const options_t &options_,
                                     const bool downgrade_sub_) :
    mechanism_base_t (session_, options_),
    curve_mechanism_base_t (session_,
                            options_,
                            "CurveZMQMESSAGEC",
                            "CurveZMQMESSAGES",
                            downgrade_sub_),
    _state (send_hello),
    _tools (options_.curve_public_key,
            options_.curve_secret_key,
            options_.curve_server_key)
{
}

zmq::curve_client_t::~curve_client_t ()
{
}

int zmq::curve_client_t::next_handshake_command (msg_t *msg_)
{
    int rc = 0;

    switch (_state) {
        case send_hello:
            rc = produce_hello (msg_);
            if (rc == 0)
                _state = expect_welcome;
            break;
        case send_initiate:
            rc = produce_initiate (msg_);
            if (rc == 0)
                _state = expect_ready;
            break;
        default:
            errno = EAGAIN;
            rc = -1;
    }
    return rc;
}

int zmq::curve_client_t::process_handshake_command (msg_t *msg_)
{
    const unsigned char *msg_data =
      static_cast<unsigned char *> (msg_->data ());
    const size_t msg_size = msg_->size ();

    int rc = 0;
    if (curve_client_tools_t::is_handshake_command_welcome (msg_data, msg_size))
        rc = process_welcome (msg_data, msg_size);
    else if (curve_client_tools_t::is_handshake_command_ready (msg_data,
                                                               msg_size))
        rc = process_ready (msg_data, msg_size);
    else if (curve_client_tools_t::is_handshake_command_error (msg_data,
                                                               msg_size))
        rc = process_error (msg_data, msg_size);
    else {
        session->get_socket ()->event_handshake_failed_protocol (
          session->get_endpoint (), ZMQ_PROTOCOL_ERROR_ZMTP_UNEXPECTED_COMMAND);
        errno = EPROTO;
        rc = -1;
    }

    if (rc == 0) {
        rc = msg_->close ();
        errno_assert (rc == 0);
        rc = msg_->init ();
        errno_assert (rc == 0);
    }

    return rc;
}

int zmq::curve_client_t::encode (msg_t *msg_)
{
    zmq_assert (_state == connected);
    return curve_mechanism_base_t::encode (msg_);
}

int zmq::curve_client_t::decode (msg_t *msg_)
{
    zmq_assert (_state == connected);
    return curve_mechanism_base_t::decode (msg_);
}

zmq::mechanism_t::status_t zmq::curve_client_t::status () const
{
    if (_state == connected)
        return mechanism_t::ready;
    if (_state == error_received)
        return mechanism_t::error;

    return mechanism_t::handshaking;
}

int zmq::curve_client_t::produce_hello (msg_t *msg_)
{
    int rc = msg_->init_size (200);
    errno_assert (rc == 0);

    rc = _tools.produce_hello (msg_->data (), get_and_inc_nonce ());
    if (rc == -1) {
        session->get_socket ()->event_handshake_failed_protocol (
          session->get_endpoint (), ZMQ_PROTOCOL_ERROR_ZMTP_CRYPTOGRAPHIC);

        // TODO this is somewhat inconsistent: we call init_size, but we may
        // not close msg_; i.e. we assume that msg_ is initialized but empty
        // (if it were non-empty, calling init_size might cause a leak!)

        // msg_->close ();
        return -1;
    }

    return 0;
}

int zmq::curve_client_t::process_welcome (const uint8_t *msg_data_,
                                          size_t msg_size_)
{
    const int rc = _tools.process_welcome (msg_data_, msg_size_,
                                           get_writable_precom_buffer ());

    if (rc == -1) {
        session->get_socket ()->event_handshake_failed_protocol (
          session->get_endpoint (), ZMQ_PROTOCOL_ERROR_ZMTP_CRYPTOGRAPHIC);

        errno = EPROTO;
        return -1;
    }

    _state = send_initiate;

    return 0;
}

int zmq::curve_client_t::produce_initiate (msg_t *msg_)
{
    const size_t metadata_length = basic_properties_len ();
    std::vector<unsigned char, secure_allocator_t<unsigned char> >
      metadata_plaintext (metadata_length);

    add_basic_properties (&metadata_plaintext[0], metadata_length);

    const size_t msg_size =
      113 + 128 + crypto_box_BOXZEROBYTES + metadata_length;
    int rc = msg_->init_size (msg_size);
    errno_assert (rc == 0);

    rc = _tools.produce_initiate (msg_->data (), msg_size, get_and_inc_nonce (),
                                  &metadata_plaintext[0], metadata_length);

    if (-1 == rc) {
        session->get_socket ()->event_handshake_failed_protocol (
          session->get_endpoint (), ZMQ_PROTOCOL_ERROR_ZMTP_CRYPTOGRAPHIC);

        // TODO see comment in produce_hello
        return -1;
    }

    return 0;
}

int zmq::curve_client_t::process_ready (const uint8_t *msg_data_,
                                        size_t msg_size_)
{
    if (msg_size_ < 30) {
        session->get_socket ()->event_handshake_failed_protocol (
          session->get_endpoint (),
          ZMQ_PROTOCOL_ERROR_ZMTP_MALFORMED_COMMAND_READY);
        errno = EPROTO;
        return -1;
    }

    const size_t clen = (msg_size_ - 14) + crypto_box_BOXZEROBYTES;

    uint8_t ready_nonce[crypto_box_NONCEBYTES];
    std::vector<uint8_t, secure_allocator_t<uint8_t> > ready_plaintext (
      crypto_box_ZEROBYTES + clen);
    std::vector<uint8_t> ready_box (crypto_box_BOXZEROBYTES + 16 + clen);

    std::fill (ready_box.begin (), ready_box.begin () + crypto_box_BOXZEROBYTES,
               0);
    memcpy (&ready_box[crypto_box_BOXZEROBYTES], msg_data_ + 14,
            clen - crypto_box_BOXZEROBYTES);

    memcpy (ready_nonce, "CurveZMQREADY---", 16);
    memcpy (ready_nonce + 16, msg_data_ + 6, 8);
    set_peer_nonce (get_uint64 (msg_data_ + 6));

    int rc = crypto_box_open_afternm (&ready_plaintext[0], &ready_box[0], clen,
                                      ready_nonce, get_precom_buffer ());

    if (rc != 0) {
        session->get_socket ()->event_handshake_failed_protocol (
          session->get_endpoint (), ZMQ_PROTOCOL_ERROR_ZMTP_CRYPTOGRAPHIC);
        errno = EPROTO;
        return -1;
    }

    rc = parse_metadata (&ready_plaintext[crypto_box_ZEROBYTES],
                         clen - crypto_box_ZEROBYTES);

    if (rc == 0)
        _state = connected;
    else {
        session->get_socket ()->event_handshake_failed_protocol (
          session->get_endpoint (), ZMQ_PROTOCOL_ERROR_ZMTP_INVALID_METADATA);
        errno = EPROTO;
    }

    return rc;
}

int zmq::curve_client_t::process_error (const uint8_t *msg_data_,
                                        size_t msg_size_)
{
    if (_state != expect_welcome && _state != expect_ready) {
        session->get_socket ()->event_handshake_failed_protocol (
          session->get_endpoint (), ZMQ_PROTOCOL_ERROR_ZMTP_UNEXPECTED_COMMAND);
        errno = EPROTO;
        return -1;
    }
    if (msg_size_ < 7) {
        session->get_socket ()->event_handshake_failed_protocol (
          session->get_endpoint (),
          ZMQ_PROTOCOL_ERROR_ZMTP_MALFORMED_COMMAND_ERROR);
        errno = EPROTO;
        return -1;
    }
    const size_t error_reason_len = static_cast<size_t> (msg_data_[6]);
    if (error_reason_len > msg_size_ - 7) {
        session->get_socket ()->event_handshake_failed_protocol (
          session->get_endpoint (),
          ZMQ_PROTOCOL_ERROR_ZMTP_MALFORMED_COMMAND_ERROR);
        errno = EPROTO;
        return -1;
    }
    const char *error_reason = reinterpret_cast<const char *> (msg_data_) + 7;
    handle_error_reason (error_reason, error_reason_len);
    _state = error_received;
    return 0;
}

#endif