Re: [lwip-users] Zero-length pbuf

[address@hidden]

At least from reading your post (not reading the source code), it seems 
you're right. Could you file a bug at 
http://savannah.nongnu.org/bugs/?group=lwip ?

Thanks,
Simon


Charles Landau wrote:
> In lwIP version 1.3.0, in core/tcp_out.c, starting at line 336 the code 
> appends the pbuf chain queue->p to the unsent queue useg. When so doing 
> it removes the TCP header from queue->p because useg already has a header.
>
> It can happen that the pbuf chain queue->p is a chain of two (or more) 
> pbufs, the first of which has only a TCP header (added at line 258). 
> Removing the TCP header leaves this pbuf with a zero length. Appending 
> this to useg using pbuf_cat() leaves the zero length pbuf in the chain. 
> This leaves a useless zero length pbuf allocated and taking up space 
> limited by TCP_SND_QUEUELEN.
>
> I suggest in this case the zero length pbuf should be freed and only the 
> rest of its chain appended to useg.
>
>
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