Re: [lwip-users] ICMP port unreachable when using netconn UDP

[Ben Bobbitt]

The connect was being called prior to a transmit, which was working 
ok.   As I mentioned in a follow up email, the problem with receive was 
that I was passing IP_ADDR_ANY to the bind() call, which, according to a 
document that I was referrring to, should have been ok. 

Once I changed that to use the real IP addr, it started receiving ok.  
The next problem was running out of netbufs, which seems to require that 
I call netbuf_delete() on the netbuf returned from the receive call, 
which seems wrong, since I didn't allocate that buffer.  However, I 
could only receive N packets, where N was the lwipopts.h config param 
for memp_netbufs ( I don't have the code in from of me right now, so 
that may not be the exact parameter).  Calling netbuf_delete() after 
using the received data fixed that problem. 

Thanks for your help. 


> > All I have done is to make the UDP related changes to the lwipopts.h 
> > file, and then in the module that was previously a webserver example: 
> > pxHTTPListener = netconn_new( NETCONN_UDP );
> >
> > addr.addr = htonl(0xc0a80002);  // my local ip 192.168.0.2
> >
> > netconn_bind(pxHTTPListener, &addr, webHttpPort );
> >
> > addr.addr = htonl(0xc0a80065);  // ip of the remote system
> >
> > netconn_connect(pxHTTPListener,&addr,webHttpPort);
>
>
> You shouldn't need to do a connect if you receive. But if you do it 
> should precisely match the remote end's IP/port. I doubt that your 
> remote system 192.168.0.65 is sending _from_ webHttpPort, and is 
> probably using a random high port number.
>
> So just don't do the connect.
>
> Jifl