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Fix bug #50824: Bug in SNTP POLL mode

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Ignore all broken packets
Stop timeouts only when correct packet is received
This commit is contained in:
Dirk Ziegelmeier 2017-04-21 22:10:52 +02:00
parent ad779e5c9c
commit 13f51a0318
1 changed files with 14 additions and 16 deletions
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30
src/apps/sntp/sntp.c
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@ -435,10 +435,6 @@ sntp_recv(void *arg, struct udp_pcb* pcb, struct pbuf *p, const ip_addr_t *addr,
LWIP_UNUSED_ARG(arg);
LWIP_UNUSED_ARG(pcb);
/* packet received: stop retry timeout */
sys_untimeout(sntp_try_next_server, NULL);
sys_untimeout(sntp_request, NULL);
err = ERR_ARG;
#if SNTP_CHECK_RESPONSE >= 1
/* check server address and port */
@ -453,7 +449,7 @@ sntp_recv(void *arg, struct udp_pcb* pcb, struct pbuf *p, const ip_addr_t *addr,
if (p->tot_len == SNTP_MSG_LEN) {
mode = pbuf_get_at(p, SNTP_OFFSET_LI_VN_MODE) & SNTP_MODE_MASK;
/* if this is a SNTP response... */
if (((sntp_opmode == SNTP_OPMODE_POLL) && (mode == SNTP_MODE_SERVER)) ||
if (((sntp_opmode == SNTP_OPMODE_POLL) && (mode == SNTP_MODE_SERVER)) ||
((sntp_opmode == SNTP_OPMODE_LISTENONLY) && (mode == SNTP_MODE_BROADCAST))) {
stratum = pbuf_get_at(p, SNTP_OFFSET_STRATUM);
@ -462,8 +458,7 @@ sntp_recv(void *arg, struct udp_pcb* pcb, struct pbuf *p, const ip_addr_t *addr,
err = SNTP_ERR_KOD;
LWIP_DEBUGF(SNTP_DEBUG_STATE, ("sntp_recv: Received Kiss-of-Death\n"));
} else {
pbuf_copy_partial(p, &timestamps, sizeof(timestamps),
SNTP_OFFSET_TIMESTAMPS);
pbuf_copy_partial(p, &timestamps, sizeof(timestamps), SNTP_OFFSET_TIMESTAMPS);
#if SNTP_CHECK_RESPONSE >= 2
/* check originate_timetamp against sntp_last_timestamp_sent */
if (timestamps.orig.sec != sntp_last_timestamp_sent.sec ||
@ -493,12 +488,18 @@ sntp_recv(void *arg, struct udp_pcb* pcb, struct pbuf *p, const ip_addr_t *addr,
err = ERR_TIMEOUT;
}
#endif /* SNTP_CHECK_RESPONSE >= 1 */
pbuf_free(p);
if (err == ERR_OK) {
/* correct packet received: process it it */
sntp_process(&timestamps);
/* Set up timeout for next request (only if poll response was received)*/
if (sntp_opmode == SNTP_OPMODE_POLL) {
sys_untimeout(sntp_try_next_server, NULL);
sys_untimeout(sntp_request, NULL);
/* Correct response, reset retry timeout */
SNTP_RESET_RETRY_TIMEOUT();
@ -506,17 +507,14 @@ sntp_recv(void *arg, struct udp_pcb* pcb, struct pbuf *p, const ip_addr_t *addr,
LWIP_DEBUGF(SNTP_DEBUG_STATE, ("sntp_recv: Scheduled next time request: %"U32_F" ms\n",
(u32_t)SNTP_UPDATE_DELAY));
}
} else if (err != ERR_TIMEOUT) {
/* Errors are only processed in case of an explicit poll response */
} else if (err == SNTP_ERR_KOD) {
/* KOD errors are only processed in case of an explicit poll response */
if (sntp_opmode == SNTP_OPMODE_POLL) {
if (err == SNTP_ERR_KOD) {
/* Kiss-of-death packet. Use another server or increase UPDATE_DELAY. */
sntp_try_next_server(NULL);
} else {
/* another error, try the same server again */
sntp_retry(NULL);
}
/* Kiss-of-death packet. Use another server or increase UPDATE_DELAY. */
sntp_try_next_server(NULL);
}
} else {
/* ignore any broken packet, poll mode: retry after timeout to avoid flooding */
}
}