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examples/device/net_lwip_webserver: Simplify example code.

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Now that tud_network_recv_renew has protections against recursion it's
safe and simpler to handle the lwip frame entirely in the same callback.
This commit is contained in:
Andrew Leech
2025-05-27 15:24:27 +10:00
parent 9021efcacb
commit b6ce41188e
1 changed files with 14 additions and 38 deletions
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48
examples/device/net_lwip_webserver/src/main.c
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@@ -69,9 +69,6 @@ try changing the first byte of tud_network_mac_address[] below from 0x02 to 0x00
/* lwip context */ /* lwip context */
static struct netif netif_data; static struct netif netif_data;
/* shared between tud_network_recv_cb() and service_traffic() */
static struct pbuf *received_frame;
/* this is used by this code, ./class/net/net_driver.c, and usb_descriptors.c */ /* this is used by this code, ./class/net/net_driver.c, and usb_descriptors.c */
/* ideally speaking, this should be generated from the hardware's unique ID (if available) */ /* ideally speaking, this should be generated from the hardware's unique ID (if available) */
/* it is suggested that the first byte is 0x02 to indicate a link-local address */ /* it is suggested that the first byte is 0x02 to indicate a link-local address */
@@ -184,9 +181,7 @@ bool dns_query_proc(const char *name, ip4_addr_t *addr) {
} }
bool tud_network_recv_cb(const uint8_t *src, uint16_t size) { bool tud_network_recv_cb(const uint8_t *src, uint16_t size) {
/* this shouldn't happen, but if we get another packet before struct netif *netif = &netif_data;
parsing the previous, we must signal our inability to accept it */
if (received_frame) return false;
if (size) { if (size) {
struct pbuf *p = pbuf_alloc(PBUF_RAW, size, PBUF_POOL); struct pbuf *p = pbuf_alloc(PBUF_RAW, size, PBUF_POOL);
@@ -199,8 +194,16 @@ bool tud_network_recv_cb(const uint8_t *src, uint16_t size) {
/* Copy buf to pbuf */ /* Copy buf to pbuf */
pbuf_take(p, src, size); pbuf_take(p, src, size);
/* store away the pointer for service_traffic() to later handle */ // Surrender ownership of our pbuf unless there was an error
received_frame = p; // Only call pbuf_free if not Ok else it will panic with "pbuf_free: p->ref > 0"
// or steal it from whatever took ownership of it with undefined consequences.
// See: https://savannah.nongnu.org/patch/index.php?10121
if (netif->input(p, netif) != ERR_OK) {
printf("ERROR: netif input failed\n");
pbuf_free(p);
}
// Signal tinyusb that the current frame has been processed.
tud_network_recv_renew();
} }
return true; return true;
@@ -214,33 +217,6 @@ uint16_t tud_network_xmit_cb(uint8_t *dst, void *ref, uint16_t arg) {
return pbuf_copy_partial(p, dst, p->tot_len, 0); return pbuf_copy_partial(p, dst, p->tot_len, 0);
} }
static void service_traffic(void) {
/* handle any packet received by tud_network_recv_cb() */
if (received_frame) {
struct netif *netif = &netif_data;
// Surrender ownership of our pbuf unless there was an error
// Only call pbuf_free if not Ok else it will panic with "pbuf_free: p->ref > 0"
// or steal it from whatever took ownership of it with undefined consequences.
// See: https://savannah.nongnu.org/patch/index.php?10121
if (netif->input(received_frame, netif) != ERR_OK) {
printf("ERROR: netif input failed\n");
pbuf_free(received_frame);
}
received_frame = NULL;
tud_network_recv_renew();
}
sys_check_timeouts();
}
void tud_network_init_cb(void) {
/* if the network is re-initializing and we have a leftover packet, we must do a cleanup */
if (received_frame) {
pbuf_free(received_frame);
received_frame = NULL;
}
}
static void handle_link_state_switch(void) { static void handle_link_state_switch(void) {
/* Check for button press to toggle link state */ /* Check for button press to toggle link state */
static bool last_link_state = true; static bool last_link_state = true;
@@ -298,7 +274,7 @@ int main(void) {
while (1) { while (1) {
tud_task(); tud_task();
service_traffic(); sys_check_timeouts(); // service lwip
handle_link_state_switch(); handle_link_state_switch();
} }