[TW#24230] lwip raw UDP sendto not working as expected #224
Description
Using lwip raw udp API, notice that only one UDP echo works then the device echoes back improperly after that (UDP packet seems to be malformed, missing payload)
#include "lwip/api.h"
#include "lwip/udp.h"
void udp_echo_recv(void *arg,
struct udp_pcb *pcb, struct pbuf *p,
const ip_addr_t *addr, u16_t port)
{
if (p != NULL) {
/* send received packet back to sender */
udp_sendto(pcb, p, addr, port);
/* free the pbuf */
pbuf_free(p);
}
}
void udp_echo_init(void)
{
struct udp_pcb * pcb;
/* get new pcb */
pcb = udp_new();
if (pcb == NULL) {
LWIP_DEBUGF(UDP_DEBUG, ("udp_new failed!\n"));
return;
}
/* bind to any IP address on port 7 */
if (udp_bind(pcb, IP_ADDR_ANY, 7) != ERR_OK) {
LWIP_DEBUGF(UDP_DEBUG, ("udp_bind failed!\n"));
return;
}
/* set udp_echo_recv() as callback function
for received packets */
udp_recv(pcb, udp_echo_recv, NULL);
}tcpdump after asking to echo '123':
00:09:21.434673 IP (tos 0x0, ttl 64, id 11414, offset 0, flags [none], proto UDP (17), length 32)
192.168.2.2.49738 > 192.168.2.179.echo: [udp sum ok] UDP, length 4
0x0000: 5ccf 7f3a 08ba 58b0 3561 d381 0800 4500 \..:..X.5a....E.
0x0010: 0020 2c96 0000 4011 c831 c0a8 0202 c0a8 ..,...@..1......
0x0020: 02b3 c24a 0007 000c 5342 3132 330a ...J....SB123.
00:09:21.636659 IP truncated-ip - 4 bytes missing! (tos 0x0, ttl 255, id 5, offset 0, flags [none], proto UDP (17), length 32)
192.168.2.179.echo > 192.168.2.2.49738: UDP, length 4
0x0000: 58b0 3561 d381 5ccf 7f3a 08ba 0800 4500 X.5a..\..:....E.
0x0010: 0020 0005 0000 ff11 35c2 c0a8 02b3 c0a8 ........5.......
0x0020: 0202 0007 c24a 000c 5342
Full code here
Any thoughts?
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