Question
Incomprehensible behavior with the LWIP library.
Recently I switched to STM32F767ZI using LAN8742A and the LWIP library. Began to develop a web configurator based on this STM. And there is such a problem. 
where 192.168.97.200 is a device, 192.168.97.1 is a client (computer).
During data transfer to get, the request goes to a packet with the SYN flag, after which the device does not transmit data, does not respond to ping.
The code is presented below.
char *buf;
struct http_state
{
char *file;
u32_t left;
};
static void
conn_err(void *arg, err_t err)
{
struct http_state *hs;
hs = arg;
mem_free(hs);
}
/*-----------------------------------------------------------------------------------*/
static void
close_conn(struct tcp_pcb *pcb, struct http_state *hs)
{
tcp_arg(pcb, NULL);
tcp_sent(pcb, NULL);
tcp_recv(pcb, NULL);
mem_free(hs);
tcp_close(pcb);
}
/*-----------------------------------------------------------------------------------*/
static void
send_data(struct tcp_pcb *pcb, struct http_state *hs)
{
err_t err;
u16_t len;
/* We cannot send more data than space avaliable in the send
buffer. */
if (tcp_sndbuf(pcb) < hs->left)
{
len = tcp_sndbuf(pcb);
}
else
{
len = hs->left;
}
err = tcp_write(pcb, hs->file, len, 0);
if (err == ERR_OK)
{
hs->file += len;
hs->left -= len;
}
}
/*-----------------------------------------------------------------------------------*/
static err_t
http_poll(void *arg, struct tcp_pcb *pcb)
{
if (arg == NULL)
{
/* printf("Null, close\n");*/
tcp_close(pcb);
}
else
{
send_data(pcb, (struct http_state *)arg);
}
return ERR_OK;
}
/*-----------------------------------------------------------------------------------*/
static err_t
http_sent(void *arg, struct tcp_pcb *pcb, u16_t len)
{
struct http_state *hs;
hs = arg;
if (hs->left > 0)
{
send_data(pcb, hs);
}
else
{
close_conn(pcb, hs);
}
return ERR_OK;
}
static err_t
http_recv(void *arg, struct tcp_pcb *pcb, struct pbuf *p, err_t err)
{
int i, j;
char *buf;
struct http_state *hs;
hs = arg;
if (err == ERR_OK && p != NULL)
{
/* Inform TCP that we have taken the data. */
tcp_recved(pcb, p->tot_len);
if (hs->file == NULL)
{
//handler
}
else
{
pbuf_free(p);
}
}
return ERR_OK;
}
static err_t
http_accept(void *arg, struct tcp_pcb *pcb, err_t err)
{
struct http_state *hs;
/* Allocate memory for the structure that holds the state of the
connection. */
hs = mem_malloc(sizeof(struct http_state));
if (hs == NULL)
{
return ERR_MEM;
}
/* Initialize the structure. */
hs->file = NULL;
hs->left = 0;
/* Tell TCP that this is the structure we wish to be passed for our
callbacks. */
tcp_arg(pcb, hs);
/* Tell TCP that we wish to be informed of incoming data by a call
to the http_recv() function. */
tcp_recv(pcb, http_recv);
tcp_err(pcb, conn_err);
tcp_poll(pcb, http_poll, 10);
return ERR_OK;
}
/*-----------------------------------------------------------------------------------*/
void
httpd_init1(void)
{
struct tcp_pcb *pcb;
pcb = tcp_new();
tcp_bind(pcb, IP_ADDR_ANY, 80);
pcb = tcp_listen(pcb);
tcp_accept(pcb, http_accept);
}Who knows what the problem is? Thank you in advance. (I want to add that I'm doing a multiplayer web configurator.)