RE: [lwip-users] Installed the new version, since allthechangesand turned on the ASSERT debug

[Joolz [RSD]]

-----Original Message-----
From: Kieran Mansley [mailto:address@hidden 
Sent: 20 March 2007 15:08
To: Mailing list for lwIP users
Subject: RE: [lwip-users] Installed the new version, since
allthechangesand turned on the ASSERT debug

On Tue, 2007-03-20 at 14:42 +0000, Joolz [RSD] wrote:
>  
> ...
> struct pbuf           *data;
> struct pbuf           *aaaa;
> 
>       data = pbuf_alloc( PBUF_RAW, 0, PBUF_RAM);
>       aaaa = pbuf_alloc( PBUF_RAW, PAYLOAD_SIZE, PBUF_ROM);
>       aaaa->payload = pvMalloc( PAYLOAD_SIZE);
>       pbuf_chain( data, aaaa);
>       outUdp = udp_new();
>       outAddr.addr = htonl( e2Prom.channelSettings.ipAddress);
>       udp_bind( outUdp, IP_ADDR_ANY, e2Prom.ethernetSettings.port);
>       udp_connect( outUdp, &outAddr, e2Prom.channelSettings.port);
>       udp_send( outUdp, data);
> 
> Does not work, different error in pbuf.c line 490

>>In short, the first pbuf you've allocated is of zero size, so there's
no room for the headers to go in there.  You need to allocate one of
sensible size.  
>>Fortunately lwIP will work out this size for you if you specify it as
PBUF_TRANSPORT rather than PBUF_RAW - that's essentially what the first
argument 
>>to pbuf alloc is for:
>>
>>eg. data = pbuf_alloc( PBUF_TRANSPORT, 0, PBUF_RAM);
>>
>>This reserves the required space, and you should be able to chain you
other one  along at the end.  Looking at the lwIP code, I think your
other pbuf should 
>>technically be of type PBUF_REF (externally referenced RAM payload)
rather than PBUF_ROM, although there is little difference between them
at the 
>>moment.
>>
>>There's a bit of internal lwIP code doing something pretty similar to
this (see tcp_out.c:227) so I'm pretty confident it should work.
>>
>>Kieran

Right tried the code and works on first udp_send but if I then send
another packet I get an assert in pbuf.c 490

..
// Setup linked buffers
        data = pbuf_alloc( PBUF_TRANSPORT, 0, PBUF_RAM);
        aaaa = pbuf_alloc( PBUF_RAW, PAYLOAD_SIZE, PBUF_REF);
        dataBuffer = pvMalloc( PAYLOAD_SIZE);
        pbuf_chain( data, aaaa);

// Send 2 buffers
        outUdp = udp_new();
        outAddr.addr = htonl( e2Prom.channelSettings.ipAddress);
        udp_bind( outUdp, IP_ADDR_ANY, e2Prom.ethernetSettings.port);
        udp_connect( outUdp, &outAddr, e2Prom.channelSettings.port);
        outUdp->flags |= UDP_FLAGS_NOCHKSUM;
        outUdp->ttl = 0x38;
        data->next->payload = dataBuffer;
        udp_send( outUdp, data);
        udp_send( outUdp, data);

Do I need to free the data, I thought that would be done by the udp_send

joolz