Problem receiving multicast

Hi Benneth,

You simply have to recall which port you bind to...Is this what you are trying to accomplish?

Thanks,

Aaron

Hi

The problem isn't the port.
If i bind my socket to multicast address 239.1.0.41 and port 50632, then it will receive all messages sent on different multicast addresses as long as it is on the same port.
For example the socket will receive message sent to 224.1.1.22 if is sent to port 50632 even though the socket was bind to another address.

So how can I do to only receive for the address I bind? Or is it a way to determine which address that was received on after the recvfrom function has been called?

BR
/Benneth

Hi,

I'm still having this problem.

Is there someone that know if this is a known problem? (If so are there any plan for fixing the problem?)

Or are there any more information available on how tu use multicast for CC3000 since it doesn't work when using the example (see original post).

BR
/Benneth 

Hi Benneth,

I'm checking to see if this is a known issue. In the meanwhile, can you post the code you are using to set up the socket?

Thanks,

Aaron

Hi,

After the wlan module has started and we have a connection, the following is used to set up the socket.
(Only included the parts related to the socket. It is used in a bigger switch/case statemachine, hence the breaks)

#define DISCOVER_PORT 50632

long wifiUdpClient;
sockaddr udpaddr;
sockaddr udpClientAddr;
socklen_t addrlen;
fd_set readsds;
long maxFD;
timeval timeout; 

//-----------

if (socket(AF_INET, SOCK_DGRAM, IPPROTO_UDP) == -1) {

    break;
}

//-----------

udpaddr.sa_family = AF_INET;
udpaddr.sa_data[0] = (DISCOVER_PORT & 0xFF00)>> 8;
udpaddr.sa_data[1] = (DISCOVER_PORT & 0x00FF);
udpaddr.sa_data[2] = 239;
udpaddr.sa_data[3] = 63;
udpaddr.sa_data[4] = 253;
udpaddr.sa_data[5] = 57; 

if (bind(wifiUdpClient, &udpaddr, sizeof(sockaddr))== -1) {
    break;
}

//-----------

FD_ZERO(&readsds);
FD_SET(wifiUdpClient, &readsds);
maxFD = wifiUdpClient + 1;
timeout.tv_sec = 0;
timeout.tv_usec = 5000;

if(select(maxFD, &readsds, NULL, NULL, &timeout) < 0) {
    break;
}
if(!FD_ISSET(wifiUdpClient,&readsds)) {
    break;
}

// Look for a request/command packet
addrlen = sizeof(sockaddr);
i = recvfrom(wifiUdpClient, &pktData[0], sizeof(pktData), 0, &udpClientAddr, &addrlen);

//Parse received message 

//-----------

With this, the checks with select and FD_ISSET will give ok for all receptions on the port that was set up and not only for thoose on the set up multicast address.
I've also tried the code from the example linked in the first post without any success. 

BR
/Benneth 

Hi Benneth,

I have not heard of this being a known issue... so I will try to reproduce. I do think this is an important issue. Please stand by.

Regards,

Aaron

Hi Benneth,

Where are you setting wifiUdpClient?

I see socket() is called without retrieving the file descriptor.

Regards,
Aaron

Hi Aaron,

looks like I managed to do some kind of copy paste error.
The code used is the following:

#define DISCOVER_PORT 50632

long wifiUdpClient;
sockaddr udpaddr;
sockaddr udpClientAddr;
socklen_t addrlen;
fd_set readsds;
long maxFD;
timeval timeout; 

//-----------

wifiUdpClient = socket(AF_INET, SOCK_DGRAM, IPPROTO_UDP);
if (wifiUdpClient == -1) {
    break;
}

//-----------

udpaddr.sa_family = AF_INET;
udpaddr.sa_data[0] = (DISCOVER_PORT & 0xFF00)>> 8;
udpaddr.sa_data[1] = (DISCOVER_PORT & 0x00FF);
udpaddr.sa_data[2] = 239;
udpaddr.sa_data[3] = 63;
udpaddr.sa_data[4] = 253;
udpaddr.sa_data[5] = 57; 

if (bind(wifiUdpClient, &udpaddr, sizeof(sockaddr))== -1) {
    break;
}

//-----------

FD_ZERO(&readsds);
FD_SET(wifiUdpClient, &readsds);
maxFD = wifiUdpClient + 1;
timeout.tv_sec = 0;
timeout.tv_usec = 5000;

if(select(maxFD, &readsds, NULL, NULL, &timeout) < 0) {
    break;
}
if(!FD_ISSET(wifiUdpClient,&readsds)) {
    break;
}

// Look for a request/command packet
addrlen = sizeof(sockaddr);
i = recvfrom(wifiUdpClient, &pktData[0], sizeof(pktData), 0, &udpClientAddr, &addrlen);

//Parse received message 

//-----------

BR
/Benneth

Hi Benneth,

I have reproduced your issue, and this does seem strange to me. I'll keep you updated with any workarounds or conclusions.

Regards,

Aaron

Hi Aaron,

Any update regarding the multicast issue?

Also, for multicast to fully work on all networks it might be necessary to implement IGMP protocol since some networks don't forward multicast traffic. What I understand there are no support for IGMP for the CC3000 today. Is there any way to implement the IGMP protocol with the current api of the CC3000

BR
/Benneth 

Hi Benneth,

We have had an internal discussion about this and have concluded there is no way for the CC3000 to recieve only multicast messages designated for a specific group. Also, with CC3000's API, IGMP is not implementable. The only possible workaround is to perhaps include group information in the payload, and simply ignore packets not in that group at the application level.

Regards,

Aaron