[zeromq-dev] No UDP broadcast message received using CZMQ zbeacon on RaspberryPi3

[Luca Boccassi]

Hi,

There is a CZMQ 4.0.x series now, loads of changes have gone in since
3.0.2. I would recommend trying it as the first thing.

https://github.com/zeromq/czmq/releases

On Mon, 2016-11-28 at 12:42 -0200, Rodrigo Madruga wrote:
> Hello all,
> 
> I am developing a system that uses CZMQ's zbeacon (broadcast on UDP) for
> app discovery. Beacon sender is Windows box and receiver is RaspberryPi3.
> 
> As the subject says, no message is reaching the zbeacon actor.
> 
> Using czmq3.0.2 and zmq4.1.6 built directly on pi to rule out
> cross-compiling issues.
> 
> Calling just zbeacon_test() returns "OK" without assertions errors.
> 
> Broadcast messages are indeed reaching the pi, as shown by tcpdump:
> 
>     pi at raspberrypi:~ $ sudo tcpdump udp port 5670
>     tcpdump: verbose output suppressed, use -v or -vv for full protocol
> decode
>     listening on wlan0, link-type EN10MB (Ethernet), capture size 262144
> bytes
>     13:33:56.203230 IP [REDACTED].5670 > 192.168.1.255.5670: UDP, length 22
>     13:34:01.072476 IP [REDACTED].5670 > 192.168.1.255.5670: UDP, length 22
> 
> The code used to test is based on zbeacon_test function:
> 
>     zactor_t *listener = zactor_new (zbeacon, NULL);
>     assert (listener);
>     zsock_send (listener, "si", "CONFIGURE", 5670);
>     hostname = zstr_recv (listener);
>     assert (*hostname);
>     free (hostname);
> 
>     zsock_send (listener, "sb", "SUBSCRIBE", "", 0);
> 
>     zpoller_t *poller = zpoller_new (listener, NULL);
>     assert (poller);
>     int64_t stop_at = zclock_mono () + 10000; // wait 10 seconds
>     while (zclock_mono () < stop_at) {
>         long timeout = (long) (stop_at - zclock_mono ());
>         if (timeout < 0)
>             timeout = 0;
>         void *which = zpoller_wait (poller, timeout * ZMQ_POLL_MSEC);
>         if (which) {
>             char *ipaddress, *received;
>             zstr_recvx (which, &ipaddress, &received, NULL);
>             printf("From address %s:%s\n", ipaddress, received);
>             zstr_free (&ipaddress);
>             zstr_free (&received);
>         }
>     }
>     zpoller_destroy (&poller);
> 
>     //  Stop listening
>     zstr_sendx (listener, "UNSUBSCRIBE", NULL);
> 
>     //  Destroy the test nodes
>     zactor_destroy (&listener);
> 
> I cross-compiled a simple Qt app with a QUdpSocket (below) and the messages
> were received without issues:
> 
>     #include <QtNetwork/QUdpSocket>
> 
>     TestUDP::TestUDP(QObject *parent) :
>         QObject(parent)
>     {
>         qDebug() << "Binding UDP Socket";
>         socket = new QUdpSocket(this);
>         socket->bind(QHostAddress::Any, 5670);
>         connect(socket, &QUdpSocket::readyRead,this, &TestUDP::readyRead);
>         qDebug() << "Ready Read signal connected0, waiting for broadcasts";
>     }
> 
>     void TestUDP::readyRead(){
>         QByteArray buffer;
>         buffer.resize(socket->pendingDatagramSize());
>         //var to store headers from udp
>         QHostAddress sender;
>         quint16 sender_port;
>         socket->readDatagram(buffer.data(),buffer.size(), &sender,
> &sender_port);
>         qDebug() << "Message from " << sender << " port " << sender_port;
>         qDebug() << "Msg: " << buffer;
>     }
> 
> Maybe the problem is at the way zbeacon is dealing with the UDP socket...
> 
> Has anyone successfully used a zbeacon on RPI3?
> 
> Thanks in advance!
> 
> Rodrigo Madruga.
> _______________________________________________
> zeromq-dev mailing list
> zeromq-dev at lists.zeromq.org
> http://lists.zeromq.org/mailman/listinfo/zeromq-dev


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