Re: [lwip-users] httpc_get_file doesn't seem to download entire file?

Dear ,

I don't think I am able to reset the timer. The 'arg' passed in

err_t rec_fn(void *arg, struct altcp_pcb *conn, struct pbuf *p, err_t err)

is not of type httpc_state_t. The rec_fn callback is called here:

static err_t
httpc_tcp_recv(void *arg, struct altcp_pcb *pcb, struct pbuf *p, err_t r)

...
...
...
    if (req->recv_fn != NULL) {
      /* directly return here: the connection migth already be aborted from the callback! */
      return req->recv_fn(req->callback_arg, pcb, p, r);
    }

So what's the deal with this function

/** http client tcp poll callback */
static err_t
httpc_tcp_poll(void *arg, struct altcp_pcb *pcb)
{
  /* implement timeout */
  httpc_state_t* req = (httpc_state_t*)arg;
  LWIP_UNUSED_ARG(pcb);
  if (req != NULL) {
    if (req->timeout_ticks) {
      req->timeout_ticks--;
    }
    if (!req->timeout_ticks) {
      return httpc_close(req, HTTPC_RESULT_ERR_TIMEOUT, 0, ERR_OK);
    }
  }
  return ERR_OK;
}

It only decreases the ticks counter. It never gets reset. So I am not allowed to download files longer than 30 secs? If the download doesn't succeed within that time, http_client closes the connection.

I would expect that either the timeout counter is reset every chunk of data which is received, or that user code (my code) would receive a pointer to the httpc_state_t so that it could reset the timer.

Can somebody please explain where I am wrong, what am I missing, or that indeed the current implementation of http_client is lacking ?

Many thanks in advance

best regards, bas

Op wo 16 jun. 2021 om 09:29 schreef Bas Prins <bas.prins3@gmail.com>:

Hi all,

I found the problem, which was rather easy to find once I convinced myself I am man enough to actually read code ;-).

But now I wonder how to solve this appropriately. The problem seems to be, that this function decreases the ticks, until the timeout period is consumed, and then simply closes the connection.

/** http client tcp poll callback */
static err_t
httpc_tcp_poll(void *arg, struct altcp_pcb *pcb)
{
  /* implement timeout */
  httpc_state_t* req = (httpc_state_t*)arg;
  LWIP_UNUSED_ARG(pcb);
  if (req != NULL) {
    if (req->timeout_ticks) {
      req->timeout_ticks--;
    }
    if (!req->timeout_ticks) {
      return httpc_close(req, HTTPC_RESULT_ERR_TIMEOUT, 0, ERR_OK);
    }
  }
  return ERR_OK;
}

So I wonder, who should be responsible for resetting the timeout counter? My code? The definition of the timeout_ticks seems to only visible for to http_client.c.

If I simply comment the line which decreases the counter the download works.

Am I still missing the obvious here?

Many thanks.

best regards, bas

Op ma 14 jun. 2021 om 22:05 schreef Bas Prins <bas.prins3@gmail.com>:
Hi Simon, all,

Fixed the problems I had which led to missing a byte occasionally.

Still unable to download a file using http_client.h. I did learn a small part. I log all arguments of

void result_fn(void *arg, httpc_result_t httpc_result, u32_t rx_content_len, u32_t srv_res, err_t err)

Which produces this log line:
2021-06-14 21:31:52,041 [DEBUG][thread: 5][UartReader] DOWNLOAD finished: httpc_result=5, rx_content_len=5019, srv_res=0, error=0

  /** Connection timed out (server didn't respond in time) */
  HTTPC_RESULT_ERR_TIMEOUT   = 5,

I attached the pcap file of tcpdump.
- It contains a couple of attempts to download the file (513KB.zip).
- It shows TCP window full warnings. I don't care too much about that now. I'll deal with that once I have a stable download going.
- It shows the result of the timeout where my STM board closes the connection.

I also attached my lwipopts.h and the loggings produced by my app (including lwip ppp logging).

Can you help me understand what is going wrong?
Why is LWIP complaining about the server not responding in time, while it seems that the server is doing just fine?

PS: obviously I tested the download on my desktop, I am able to download the file repeatedly.

Many thanks in advance!

Best regards, Bas

Op vr 11 jun. 2021 om 07:15 schreef goldsimon@gmx.de <goldsimon@gmx.de>:
Am 10.06.2021 um 17:27 schrieb Bas Prins:
> Hi Simon,
>
> Thanks, that's a very likely explanation already. I just added the
> pbuf_free(p) but run into an assert occasionally.

You might have to check for 'p != NULL' just like in tcp recv callback
functions.

Regards,
Simon

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From:	Bas Prins
Subject:	Re: [lwip-users] httpc_get_file doesn't seem to download entire file?
Date:	Wed, 16 Jun 2021 13:23:52 +0200