Re: [lwip-users] file upload

[Kieran Mansley]

On Thu, 2007-03-08 at 15:55 +0100, Heike Lepke wrote:
> 
> err_t
> http_recv(void *arg, struct tcp_pcb *pcb, struct pbuf *p, err_t err)
> {
>    int i;
>    struct http_state *hs;
>    T_CHAR *pc_rq;
>    hs = reinterpret_cast<http_state*>(arg);
>    hs->file = hs->mem;
> 
>    if(err == ERR_OK && p != NULL)
>    {
> 
>      /* Inform TCP that we have taken the data. */
>      tcp_recved(pcb, p->tot_len);
>      /* Send the data to the http-Server. */
>       hs->left = 
> reinterpret_cast<http_state*>(arg)->myServer->HandleRequest(static_cast<T_CHAR*>(p->payload),p->len,hs->file,BUFFER_SIZE);
> ...
> ###############################################################################################################################
> 
> In this function I get the pbuf p, with the p->len e.g. 600, but the 
> real length of the data is 1400, whereby the data after the first 600 
> bytes is the part of the file to upload.
> The upload-file I can see in the p->payload+600 following.

Ahh, could it be that this pbuf is part of a pbuf chain?  p->len tells
you the length of each individual pbuf, p->tot_len (for the first one in
the chain) tells you the total length of all the pbufs in the chain.  p-
>next lets you access the next pbuf in the chain.

Also, you should only be calling tcp_recved() after you have finished
accessing the data - i.e. copied it to your own memory or have no
further use for it.  If you don't, it's possible that the stack will
overwrite the packet data with a new packet.  Putting it at the end of
your http_recv() function should probably be sufficient. 

Kieran