MQX Software SolutionsのトピックRe: RTCS doesn't receive broadcast datagrams on subnet, bug?

RTCS doesn't receive broadcast datagrams on subnet, bug?

TomR — Mon, 28 Feb 2011 00:16:47 GMT

I am trying to send UDP frames to an MQX system using broadcast messages.

The MQX system has a DHCP assigned IP address of 192.168.0.5 and a netmask of 255.255.255.0.

UDP frames sent to 192.168.0.5 are rx ok
UDP frames sent to 255.255.255.255 are rx ok
UDP frames sent to 192.168.0.255 are not rx

Sniffing the wire, both the 255.255.255.255 and 192.168.0.255 frames are sent with a destination MAC address of ff:ff:ff:ff:ff:ff as expected.

RTCS IP statistics show the UDP frames sent to 192.168.0.255 are being discarded.

This seems broken. I have a different platform (non-MQX) where is works.

Is there a setting that I'm overlooking?

My code looks like this:

struct sockaddr_in any;

udp_ethernet = socket(PF_INET, SOCK_DGRAM, 0);

any.sin_family = AF_INET;

any.sin_port = MY_PORT;

any.sin_addr.s_addr = INADDR_ANY;

bind(udp_ethernet, &any, sizeof(any));

rlen = sizeof(raddr);

memset(&raddr, 0, rlen);

len = recvfrom(udp_ethernet, data, DATA_LEN, 0, &raddr, &rlen);

Thanks

Tom

Re: RTCS doesn't receive broadcast datagrams on subnet, bug?

TomR — Tue, 01 Mar 2011 04:35:04 GMT

Additional debugging info:

The datagram sent to 192.168.0.255 is being dropped in the function IP_route_local(). It discards the packet and increments the rx discarded count and the rx addr errors count.

Re: RTCS doesn't receive broadcast datagrams on subnet, bug?

boogy — Thu, 03 Mar 2011 00:50:15 GMT

You have gotten farther than me. I can't recieve a broadcast (255,255,255,255) datagram.

I am currently using a stream socket and wanted to add a datagram socket to recieve broadcast datagrams.

What settings allow the reception of UDP broadcasts ?

Re: RTCS doesn't receive broadcast datagrams on subnet, bug?

TomR — Thu, 03 Mar 2011 10:59:09 GMT

The code fragment above will do the trick. Nothing more is needed on the receive side.

Typically the problem to send a broadcast datagram is on the sending end. Make sure that you've done a setsockopt(SO_BROADCAST) on the sending socket.

Have you sniffed the wire and observed that the packet is being sent on the wire?

Re: RTCS doesn't receive broadcast datagrams on subnet, bug?

DiegoSpinola — Thu, 05 May 2011 22:02:41 GMT

@TomR

I'm having the exact same issue , have you been able to solve it ?

Re: RTCS doesn't receive broadcast datagrams on subnet, bug?

DiegoSpinola — Thu, 29 Oct 2020 09:37:59 GMT

Solved!

Recompile your Libs with the RTCSCFG_IP_DISABLE_DIRECTED_BROADCAST defined to 0 at user_config.h

#define RTCSCFG_IP_DISABLE_DIRECTED_BROADCAST 0

Re: RTCS doesn't receive broadcast datagrams on subnet, bug?

dank60 — Fri, 05 Apr 2013 08:28:02 GMT

I tried to do this and it works if I build my libs in debug configuration. If I build them in release configuration I can't receive broadcast frames... I don't know what I have to do...

Re: RTCS doesn't receive broadcast datagrams on subnet, bug?

dank60 — Fri, 05 Apr 2013 09:17:32 GMT

I tried building rtcs library with different compiler's optimization levels : with level 1 no problem, with level 2 or superior broadcast udp reception doesn't work.