Re: [lwip-devel] pbuf_cat() does not update total_len

[address@hidden]

Laurenz Kamp wrote:
> First pbuf:     a.len = 10;
>                 a.total_len = 25;
>                 a.next = b;
> Second pbuf:    b.len = 15;
>                 b.total_len = 15;  <-- Should be 25.
>                 b.next = NULL;

Laurenz, your assumption is wrong. The above numbers are exactly right 
as they are.

> As far as I understand, all pbufs in a chain have the same total_len value, but 
> pbuf_cat doesn't
> update b.total_len. Is this behavior intentioned or a bug?

As written above, it's expected behaviour. And the reason for this is 
that you can create or hide network headers in the pbuf (as it gets 
passed up or down the stack) and don't need to manipulate the whole 
chain but only the first pbuf in it.

Simon