[lwip-users] http_client.c - heap memory overflow

[Jaroslav]

Hello,
I am using LWIP 2.1.2 + FreeRTOS 10 on board TM4C1294XL. I am trying to 
push measured data to a web server using http_client.c. I mannaged to 
make it working based on example in 
https://lists.nongnu.org/archive/html/lwip-users/2019-07/msg00001.

However, with each calling of httpc_get_file_dns usage of heap memory 
increases, and after approx 500th calling the application stops working 
due to heap memory overflow:

MEM HEAP:
        avail: 32768
        used: 31948
        max: 32732
        err: 561

and I am getting the following erros:

httpc_result: 7
memp_malloc: out of memory in pool TCP_PCB
mem_malloc: could not allocate 412 bytes

Here is my simplified code:

--------------------------------------------------------
#define STACKSIZE_HTTPCTASK       4096

err_t
RecvCallback(void *arg, struct tcp_pcb *tpcb, struct pbuf *p, err_t err)
{
    char str[100];
    if (p == NULL)
       UARTprintf("NULL TCP packet received\n");
    else
    {
        memcpy(&str, p->payload, p->len);
    if(strstr(str, "success") == NULL)
        UARTprintf("GET FAILED: %s\n", str);
    }
     pbuf_free(p);
     tcp_close(tpcb);
     return ERR_OK;
}

err_t
RecvHttpHeaderCallback(httpc_state_t *connection, void *arg, struct pbuf 
*hdr, u16_t hdr_len, u32_t content_len)
{
    return ERR_OK;
}

void
HttpClientResultCallback(void *arg, httpc_result_t httpc_result, u32_t 
rx_content_len, u32_t srv_res, err_t err)
{
    UARTprintf("httpc_result: %u\n", httpc_result);
    UARTprintf("received number of bytes: %lu\n", rx_content_len);
}

static void
HttpcTask(void *pvParameters)
{
    portTickType ui32LastTime;
    httpc_connection_t conn_settings;
    httpc_state_t *connection;

    conn_settings.use_proxy = 0;
    conn_settings.headers_done_fn = RecvHttpHeaderCallback;
    conn_settings.result_fn = HttpClientResultCallback;
    ui32LastTime = xTaskGetTickCount();

    while(1)
    {
    httpc_get_file_dns("my.domain.com", 80, "/write.php?d=myData", 
&conn_settings, RecvCallback, NULL, &connection);
    vTaskDelayUntil(&ui32LastTime, g_ui32HttpcDelay / portTICK_RATE_MS);
    }
}

uint32_t
HttpcTaskInit(void)
{
    xTaskCreate(HttpcTask, (const portCHAR *)"Httpc", 
STACKSIZE_HTTPCTASK, NULL,
                   tskIDLE_PRIORITY + PRIORITY_HTTPC_TASK, NULL)
    return(0);
}
------------------------------------------------------------

Any idea what I am doing wrong?

Thanks

Jaroslav