v1_encoder.cpp

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

#include "precompiled.hpp"
#include "encoder.hpp"
#include "v1_encoder.hpp"
#include "msg.hpp"
#include "wire.hpp"

#include <limits.h>

zmq::v1_encoder_t::v1_encoder_t (size_t bufsize_) :
    encoder_base_t<v1_encoder_t> (bufsize_)
{
    //  Write 0 bytes to the batch and go to message_ready state.
    next_step (NULL, 0, &v1_encoder_t::message_ready, true);
}

zmq::v1_encoder_t::~v1_encoder_t ()
{
}

void zmq::v1_encoder_t::size_ready ()
{
    //  Write message body into the buffer.
    next_step (in_progress ()->data (), in_progress ()->size (),
               &v1_encoder_t::message_ready, true);
}

void zmq::v1_encoder_t::message_ready ()
{
    size_t header_size = 2; // flags byte + size byte
    //  Get the message size.
    size_t size = in_progress ()->size ();

    //  Account for the 'flags' byte.
    size++;

    //  Account for the subscribe/cancel byte.
    if (in_progress ()->is_subscribe () || in_progress ()->is_cancel ())
        size++;

    //  For messages less than 255 bytes long, write one byte of message size.
    //  For longer messages write 0xff escape character followed by 8-byte
    //  message size. In both cases 'flags' field follows.
    if (size < UCHAR_MAX) {
        _tmpbuf[0] = static_cast<unsigned char> (size);
        _tmpbuf[1] = (in_progress ()->flags () & msg_t::more);
    } else {
        _tmpbuf[0] = UCHAR_MAX;
        put_uint64 (_tmpbuf + 1, size);
        _tmpbuf[9] = (in_progress ()->flags () & msg_t::more);
        header_size = 10;
    }

    //  Encode the subscribe/cancel byte. This is done in the encoder as
    //  opposed to when the subscribe message is created to allow different
    //  protocol behaviour on the wire in the v3.1 and legacy encoders.
    //  It results in the work being done multiple times in case the sub
    //  is sending the subscription/cancel to multiple pubs, but it cannot
    //  be avoided. This processing can be moved to xsub once support for
    //  ZMTP < 3.1 is dropped.
    if (in_progress ()->is_subscribe ())
        _tmpbuf[header_size++] = 1;
    else if (in_progress ()->is_cancel ())
        _tmpbuf[header_size++] = 0;

    next_step (_tmpbuf, header_size, &v1_encoder_t::size_ready, false);
}