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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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24
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(arg);
LWIP_UNUSED_ARG(pcb); LWIP_UNUSED_ARG(pcb);
/* packet received: stop retry timeout */
sys_untimeout(sntp_try_next_server, NULL);
sys_untimeout(sntp_request, NULL);
err = ERR_ARG; err = ERR_ARG;
#if SNTP_CHECK_RESPONSE >= 1 #if SNTP_CHECK_RESPONSE >= 1
/* check server address and port */ /* check server address and port */
@ -462,8 +458,7 @@ sntp_recv(void *arg, struct udp_pcb* pcb, struct pbuf *p, const ip_addr_t *addr,
err = SNTP_ERR_KOD; err = SNTP_ERR_KOD;
LWIP_DEBUGF(SNTP_DEBUG_STATE, ("sntp_recv: Received Kiss-of-Death\n")); LWIP_DEBUGF(SNTP_DEBUG_STATE, ("sntp_recv: Received Kiss-of-Death\n"));
} else { } else {
pbuf_copy_partial(p, &timestamps, sizeof(timestamps), pbuf_copy_partial(p, &timestamps, sizeof(timestamps), SNTP_OFFSET_TIMESTAMPS);
SNTP_OFFSET_TIMESTAMPS);
#if SNTP_CHECK_RESPONSE >= 2 #if SNTP_CHECK_RESPONSE >= 2
/* check originate_timetamp against sntp_last_timestamp_sent */ /* check originate_timetamp against sntp_last_timestamp_sent */
if (timestamps.orig.sec != sntp_last_timestamp_sent.sec || 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; err = ERR_TIMEOUT;
} }
#endif /* SNTP_CHECK_RESPONSE >= 1 */ #endif /* SNTP_CHECK_RESPONSE >= 1 */
pbuf_free(p); pbuf_free(p);
if (err == ERR_OK) { if (err == ERR_OK) {
/* correct packet received: process it it */
sntp_process(&timestamps); sntp_process(&timestamps);
/* Set up timeout for next request (only if poll response was received)*/ /* Set up timeout for next request (only if poll response was received)*/
if (sntp_opmode == SNTP_OPMODE_POLL) { if (sntp_opmode == SNTP_OPMODE_POLL) {
sys_untimeout(sntp_try_next_server, NULL);
sys_untimeout(sntp_request, NULL);
/* Correct response, reset retry timeout */ /* Correct response, reset retry timeout */
SNTP_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", LWIP_DEBUGF(SNTP_DEBUG_STATE, ("sntp_recv: Scheduled next time request: %"U32_F" ms\n",
(u32_t)SNTP_UPDATE_DELAY)); (u32_t)SNTP_UPDATE_DELAY));
} }
} else if (err != ERR_TIMEOUT) { } else if (err == SNTP_ERR_KOD) {
/* Errors are only processed in case of an explicit poll response */ /* KOD errors are only processed in case of an explicit poll response */
if (sntp_opmode == SNTP_OPMODE_POLL) { if (sntp_opmode == SNTP_OPMODE_POLL) {
if (err == SNTP_ERR_KOD) {
/* Kiss-of-death packet. Use another server or increase UPDATE_DELAY. */ /* Kiss-of-death packet. Use another server or increase UPDATE_DELAY. */
sntp_try_next_server(NULL); sntp_try_next_server(NULL);
}
} else { } else {
/* another error, try the same server again */ /* ignore any broken packet, poll mode: retry after timeout to avoid flooding */
sntp_retry(NULL);
}
}
} }
} }