Re: [lwip-users] Simultaneous GET requests to HTTP Server

[Simon Goldschmidt]

Simeon Trifonov wrote:
> I' looking in the content of the corresponding pcb, especially the member 
> "unacked". Here is what I see:
> The variable "len" seems to be ok - 1460. The pointer "p" points the buffer 
> with "len" set to 54 and "tot_len" set to 1514.
> This seems to be correct too. The pointer "next" is valid (not null), so it 
> must point the rest of the frame (1514 bytes).

I don't want to include your screenshots again, so I'll try to do without.
What you see is a segment of 1460 bytes of user data (unacked->len). Now that 
segment has already been sent, so the pbufs contain
headers (ETH, IPv4, TCP = 54 bytes). These are stored in an extra pbuf so the 
whole frame is 1514 bytes long.

In theory, the first pbuf of this segment is OK (len=54, tot_len=1514), but the 
next should be len=tot_len=1460, so definitively,
there is something wrong.

At first sight of such problems, I always assume violation of lwIP's threading 
requirements (don't call into the core code from
more than one thread or from thread + interrupt). But this also could be 
something completely different.

What's strange is that the pbuf's type, ref and payload seem to be OK but the 
len not. My best suggestion is try to check your code
if there's something that could overwrite these fields...

Simon