source: UsbWattMeter/trunk/lwip-1.4.1/apps/sntp/sntp.c@ 164

Last change on this file since 164 was 164, checked in by coas-nagasima, 6 years ago

TOPPERS/ECNLサンプルアプリ「USB充電器電力計」を追加

  • Property svn:eol-style set to native
  • Property svn:keywords set to Id
  • Property svn:mime-type set to text/x-csrc
File size: 19.5 KB
Line 
1/**
2 * @file
3 * SNTP client module
4 *
5 * This is simple "SNTP" client for the lwIP raw API.
6 * It is a minimal implementation of SNTPv4 as specified in RFC 4330.
7 *
8 * For a list of some public NTP servers, see this link :
9 * http://support.ntp.org/bin/view/Servers/NTPPoolServers
10 *
11 * @todo:
12 * - set/change servers at runtime
13 * - complete SNTP_CHECK_RESPONSE checks 3 and 4
14 * - support broadcast/multicast mode?
15 */
16
17/*
18 * Redistribution and use in source and binary forms, with or without modification,
19 * are permitted provided that the following conditions are met:
20 *
21 * 1. Redistributions of source code must retain the above copyright notice,
22 * this list of conditions and the following disclaimer.
23 * 2. Redistributions in binary form must reproduce the above copyright notice,
24 * this list of conditions and the following disclaimer in the documentation
25 * and/or other materials provided with the distribution.
26 * 3. The name of the author may not be used to endorse or promote products
27 * derived from this software without specific prior written permission.
28 *
29 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED
30 * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
31 * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT
32 * SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
33 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT
34 * OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
35 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
36 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING
37 * IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY
38 * OF SUCH DAMAGE.
39 *
40 * This file is part of the lwIP TCP/IP stack.
41 *
42 * Author: Simon Goldschmidt (lwIP raw API part)
43 */
44
45#include "lwip/opt.h"
46
47#include "sntp.h"
48
49#include "lwip/timers.h"
50#include "lwip/udp.h"
51#include "lwip/dns.h"
52#include "lwip/ip_addr.h"
53#include "lwip/pbuf.h"
54
55#include <string.h>
56#include <time.h>
57
58#if LWIP_UDP
59
60/**
61 * SNTP_DEBUG: Enable debugging for SNTP.
62 */
63#ifndef SNTP_DEBUG
64#define SNTP_DEBUG LWIP_DBG_OFF
65#endif
66
67/** SNTP server port */
68#ifndef SNTP_PORT
69#define SNTP_PORT 123
70#endif
71
72/** Set this to 1 to allow SNTP_SERVER_ADDRESS to be a DNS name */
73#ifndef SNTP_SERVER_DNS
74#define SNTP_SERVER_DNS 0
75#endif
76
77/** Set this to 1 to support more than one server */
78#ifndef SNTP_SUPPORT_MULTIPLE_SERVERS
79#define SNTP_SUPPORT_MULTIPLE_SERVERS 0
80#endif
81
82/** \def SNTP_SERVER_ADDRESS
83 * \brief SNTP server address:
84 * - as IPv4 address in "u32_t" format
85 * - as a DNS name if SNTP_SERVER_DNS is set to 1
86 * May contain multiple server names (e.g. "pool.ntp.org","second.time.server")
87 */
88#ifndef SNTP_SERVER_ADDRESS
89#if SNTP_SERVER_DNS
90#define SNTP_SERVER_ADDRESS "pool.ntp.org"
91#else
92#define SNTP_SERVER_ADDRESS "213.161.194.93" /* pool.ntp.org */
93#endif
94#endif
95
96/** Sanity check:
97 * Define this to
98 * - 0 to turn off sanity checks (default; smaller code)
99 * - >= 1 to check address and port of the response packet to ensure the
100 * response comes from the server we sent the request to.
101 * - >= 2 to check returned Originate Timestamp against Transmit Timestamp
102 * sent to the server (to ensure response to older request).
103 * - >= 3 @todo: discard reply if any of the LI, Stratum, or Transmit Timestamp
104 * fields is 0 or the Mode field is not 4 (unicast) or 5 (broadcast).
105 * - >= 4 @todo: to check that the Root Delay and Root Dispersion fields are each
106 * greater than or equal to 0 and less than infinity, where infinity is
107 * currently a cozy number like one second. This check avoids using a
108 * server whose synchronization source has expired for a very long time.
109 */
110#ifndef SNTP_CHECK_RESPONSE
111#define SNTP_CHECK_RESPONSE 0
112#endif
113
114/** According to the RFC, this shall be a random delay
115 * between 1 and 5 minutes (in milliseconds) to prevent load peaks.
116 * This can be defined to a random generation function,
117 * which must return the delay in milliseconds as u32_t.
118 * Turned off by default.
119 */
120#ifndef SNTP_STARTUP_DELAY
121#define SNTP_STARTUP_DELAY 0
122#endif
123
124/** SNTP receive timeout - in milliseconds
125 * Also used as retry timeout - this shouldn't be too low.
126 * Default is 3 seconds.
127 */
128#ifndef SNTP_RECV_TIMEOUT
129#define SNTP_RECV_TIMEOUT 3000
130#endif
131
132/** SNTP update delay - in milliseconds
133 * Default is 1 hour.
134 */
135#ifndef SNTP_UPDATE_DELAY
136#define SNTP_UPDATE_DELAY 3600000
137#endif
138#if (SNTP_UPDATE_DELAY < 15000) && !SNTP_SUPPRESS_DELAY_CHECK
139#error "SNTPv4 RFC 4330 enforces a minimum update time of 15 seconds!"
140#endif
141
142/** SNTP macro to change system time and/or the update the RTC clock */
143#ifndef SNTP_SET_SYSTEM_TIME
144#define SNTP_SET_SYSTEM_TIME(sec) ((void)sec)
145#endif
146
147/** SNTP macro to change system time including microseconds */
148#ifdef SNTP_SET_SYSTEM_TIME_US
149#define SNTP_CALC_TIME_US 1
150#define SNTP_RECEIVE_TIME_SIZE 2
151#else
152#define SNTP_SET_SYSTEM_TIME_US(sec, us)
153#define SNTP_CALC_TIME_US 0
154#define SNTP_RECEIVE_TIME_SIZE 1
155#endif
156
157/** SNTP macro to get system time, used with SNTP_CHECK_RESPONSE >= 2
158 * to send in request and compare in response.
159 */
160#ifndef SNTP_GET_SYSTEM_TIME
161#define SNTP_GET_SYSTEM_TIME(sec, us) do { (sec) = 0; (us) = 0; } while(0)
162#endif
163
164/** Default retry timeout (in milliseconds) if the response
165 * received is invalid.
166 * This is doubled with each retry until SNTP_RETRY_TIMEOUT_MAX is reached.
167 */
168#ifndef SNTP_RETRY_TIMEOUT
169#define SNTP_RETRY_TIMEOUT SNTP_RECV_TIMEOUT
170#endif
171
172/** Maximum retry timeout (in milliseconds). */
173#ifndef SNTP_RETRY_TIMEOUT_MAX
174#define SNTP_RETRY_TIMEOUT_MAX (SNTP_RETRY_TIMEOUT * 10)
175#endif
176
177/** Increase retry timeout with every retry sent
178 * Default is on to conform to RFC.
179 */
180#ifndef SNTP_RETRY_TIMEOUT_EXP
181#define SNTP_RETRY_TIMEOUT_EXP 1
182#endif
183
184/* the various debug levels for this file */
185#define SNTP_DEBUG_TRACE (SNTP_DEBUG | LWIP_DBG_TRACE)
186#define SNTP_DEBUG_STATE (SNTP_DEBUG | LWIP_DBG_STATE)
187#define SNTP_DEBUG_WARN (SNTP_DEBUG | LWIP_DBG_LEVEL_WARNING)
188#define SNTP_DEBUG_WARN_STATE (SNTP_DEBUG | LWIP_DBG_LEVEL_WARNING | LWIP_DBG_STATE)
189#define SNTP_DEBUG_SERIOUS (SNTP_DEBUG | LWIP_DBG_LEVEL_SERIOUS)
190
191#define SNTP_ERR_KOD 1
192
193/* SNTP protocol defines */
194#define SNTP_MSG_LEN 48
195
196#define SNTP_OFFSET_LI_VN_MODE 0
197#define SNTP_LI_MASK 0xC0
198#define SNTP_LI_NO_WARNING 0x00
199#define SNTP_LI_LAST_MINUTE_61_SEC 0x01
200#define SNTP_LI_LAST_MINUTE_59_SEC 0x02
201#define SNTP_LI_ALARM_CONDITION 0x03 /* (clock not synchronized) */
202
203#define SNTP_VERSION_MASK 0x38
204#define SNTP_VERSION (4/* NTP Version 4*/<<3)
205
206#define SNTP_MODE_MASK 0x07
207#define SNTP_MODE_CLIENT 0x03
208#define SNTP_MODE_SERVER 0x04
209#define SNTP_MODE_BROADCAST 0x05
210
211#define SNTP_OFFSET_STRATUM 1
212#define SNTP_STRATUM_KOD 0x00
213
214#define SNTP_OFFSET_ORIGINATE_TIME 24
215#define SNTP_OFFSET_RECEIVE_TIME 32
216#define SNTP_OFFSET_TRANSMIT_TIME 40
217
218/* number of seconds between 1900 and 1970 */
219#define DIFF_SEC_1900_1970 (2208988800UL)
220
221/**
222 * SNTP packet format (without optional fields)
223 * Timestamps are coded as 64 bits:
224 * - 32 bits seconds since Jan 01, 1970, 00:00
225 * - 32 bits seconds fraction (0-padded)
226 * For future use, if the MSB in the seconds part is set, seconds are based
227 * on Feb 07, 2036, 06:28:16.
228 */
229#ifdef PACK_STRUCT_USE_INCLUDES
230# include "arch/bpstruct.h"
231#endif
232PACK_STRUCT_BEGIN
233struct sntp_msg {
234 PACK_STRUCT_FIELD(u8_t li_vn_mode);
235 PACK_STRUCT_FIELD(u8_t stratum);
236 PACK_STRUCT_FIELD(u8_t poll);
237 PACK_STRUCT_FIELD(u8_t precision);
238 PACK_STRUCT_FIELD(u32_t root_delay);
239 PACK_STRUCT_FIELD(u32_t root_dispersion);
240 PACK_STRUCT_FIELD(u32_t reference_identifier);
241 PACK_STRUCT_FIELD(u32_t reference_timestamp[2]);
242 PACK_STRUCT_FIELD(u32_t originate_timestamp[2]);
243 PACK_STRUCT_FIELD(u32_t receive_timestamp[2]);
244 PACK_STRUCT_FIELD(u32_t transmit_timestamp[2]);
245} PACK_STRUCT_STRUCT;
246PACK_STRUCT_END
247#ifdef PACK_STRUCT_USE_INCLUDES
248# include "arch/epstruct.h"
249#endif
250
251/* function prototypes */
252static void sntp_request(void *arg);
253
254/** The UDP pcb used by the SNTP client */
255static struct udp_pcb* sntp_pcb;
256/** Addresses of servers */
257static char* sntp_server_addresses[] = {SNTP_SERVER_ADDRESS};
258#if SNTP_SUPPORT_MULTIPLE_SERVERS
259/** The currently used server (initialized to 0) */
260static u8_t sntp_current_server;
261static u8_t sntp_num_servers = sizeof(sntp_server_addresses)/sizeof(char*);
262#else /* SNTP_SUPPORT_MULTIPLE_SERVERS */
263#define sntp_current_server 0
264#endif /* SNTP_SUPPORT_MULTIPLE_SERVERS */
265
266#if SNTP_RETRY_TIMEOUT_EXP
267#define SNTP_RESET_RETRY_TIMEOUT() sntp_retry_timeout = SNTP_RETRY_TIMEOUT
268/** Retry time, initialized with SNTP_RETRY_TIMEOUT and doubled with each retry. */
269static u32_t sntp_retry_timeout;
270#else /* SNTP_RETRY_TIMEOUT_EXP */
271#define SNTP_RESET_RETRY_TIMEOUT()
272#define sntp_retry_timeout SNTP_RETRY_TIMEOUT
273#endif /* SNTP_RETRY_TIMEOUT_EXP */
274
275#if SNTP_CHECK_RESPONSE >= 1
276/** Saves the last server address to compare with response */
277static ip_addr_t sntp_last_server_address;
278#endif /* SNTP_CHECK_RESPONSE >= 1 */
279
280#if SNTP_CHECK_RESPONSE >= 2
281/** Saves the last timestamp sent (which is sent back by the server)
282 * to compare against in response */
283static u32_t sntp_last_timestamp_sent[2];
284#endif /* SNTP_CHECK_RESPONSE >= 2 */
285
286/**
287 * SNTP processing of received timestamp
288 */
289static void
290sntp_process(u32_t *receive_timestamp)
291{
292 /* convert SNTP time (1900-based) to unix GMT time (1970-based)
293 * @todo: if MSB is 1, SNTP time is 2036-based!
294 */
295 time_t t = (ntohl(receive_timestamp[0]) - DIFF_SEC_1900_1970);
296
297#if SNTP_CALC_TIME_US
298 u32_t us = ntohl(receive_timestamp[1]) / 4295;
299 SNTP_SET_SYSTEM_TIME_US(t, us);
300 /* display local time from GMT time */
301 LWIP_DEBUGF(SNTP_DEBUG_TRACE, ("sntp_process: %s, %"U32_F" us", ctime(&t), us));
302
303#else /* SNTP_CALC_TIME_US */
304
305 /* change system time and/or the update the RTC clock */
306 SNTP_SET_SYSTEM_TIME(t);
307 /* display local time from GMT time */
308 LWIP_DEBUGF(SNTP_DEBUG_TRACE, ("sntp_process: %s", ctime(&t)));
309#endif /* SNTP_CALC_TIME_US */
310}
311
312/**
313 * Initialize request struct to be sent to server.
314 */
315static void
316sntp_initialize_request(struct sntp_msg *req)
317{
318 memset(req, 0, SNTP_MSG_LEN);
319 req->li_vn_mode = SNTP_LI_NO_WARNING | SNTP_VERSION | SNTP_MODE_CLIENT;
320
321#if SNTP_CHECK_RESPONSE >= 2
322 {
323 u32_t sntp_time_sec, sntp_time_us;
324 /* fill in transmit timestamp and save it in 'sntp_last_timestamp_sent' */
325 SNTP_GET_SYSTEM_TIME(sntp_time_sec, sntp_time_us);
326 sntp_last_timestamp_sent[0] = htonl(sntp_time_sec + DIFF_SEC_1900_1970);
327 req->transmit_timestamp[0] = sntp_last_timestamp_sent[0];
328 /* we send/save us instead of fraction to be faster... */
329 sntp_last_timestamp_sent[1] = htonl(sntp_time_us);
330 req->transmit_timestamp[1] = sntp_last_timestamp_sent[1];
331 }
332#endif /* SNTP_CHECK_RESPONSE >= 2 */
333}
334
335/**
336 * Retry: send a new request (and increase retry timeout).
337 *
338 * @param arg is unused (only necessary to conform to sys_timeout)
339 */
340static void
341sntp_retry(void* arg)
342{
343 LWIP_UNUSED_ARG(arg);
344
345 LWIP_DEBUGF(SNTP_DEBUG_STATE, ("sntp_retry: Next request will be sent in %"U32_F" ms\n",
346 sntp_retry_timeout));
347
348 /* set up a timer to send a retry and increase the retry delay */
349 sys_timeout(sntp_retry_timeout, sntp_request, NULL);
350
351#if SNTP_RETRY_TIMEOUT_EXP
352 {
353 u32_t new_retry_timeout;
354 /* increase the timeout for next retry */
355 new_retry_timeout = sntp_retry_timeout << 1;
356 /* limit to maximum timeout and prevent overflow */
357 if ((new_retry_timeout <= SNTP_RETRY_TIMEOUT_MAX) &&
358 (new_retry_timeout > sntp_retry_timeout)) {
359 sntp_retry_timeout = new_retry_timeout;
360 }
361 }
362#endif /* SNTP_RETRY_TIMEOUT_EXP */
363}
364
365#if SNTP_SUPPORT_MULTIPLE_SERVERS
366/**
367 * If Kiss-of-Death is received (or another packet parsing error),
368 * try the next server or retry the current server and increase the retry
369 * timeout if only one server is available.
370 *
371 * @param arg is unused (only necessary to conform to sys_timeout)
372 */
373static void
374sntp_try_next_server(void* arg)
375{
376 LWIP_UNUSED_ARG(arg);
377
378 if (sntp_num_servers > 1) {
379 /* new server: reset retry timeout */
380 SNTP_RESET_RETRY_TIMEOUT();
381 sntp_current_server++;
382 if (sntp_current_server >= sntp_num_servers) {
383 sntp_current_server = 0;
384 }
385 LWIP_DEBUGF(SNTP_DEBUG_STATE, ("sntp_try_next_server: Sending request to server %"U16_F"\n",
386 (u16_t)sntp_current_server));
387 /* instantly send a request to the next server */
388 sntp_request(NULL);
389 } else {
390 sntp_retry(NULL);
391 }
392}
393#else /* SNTP_SUPPORT_MULTIPLE_SERVERS */
394/* Always retry on error if only one server is supported */
395#define sntp_try_next_server sntp_retry
396#endif /* SNTP_SUPPORT_MULTIPLE_SERVERS */
397
398/** UDP recv callback for the sntp pcb */
399static void
400sntp_recv(void *arg, struct udp_pcb* pcb, struct pbuf *p, ip_addr_t *addr, u16_t port)
401{
402 u8_t mode;
403 u8_t stratum;
404 u32_t receive_timestamp[SNTP_RECEIVE_TIME_SIZE];
405 err_t err;
406
407 LWIP_UNUSED_ARG(arg);
408 LWIP_UNUSED_ARG(pcb);
409
410 /* packet received: stop retry timeout */
411 sys_untimeout(sntp_try_next_server, NULL);
412 sys_untimeout(sntp_request, NULL);
413
414 err = ERR_ARG;
415#if SNTP_CHECK_RESPONSE >= 1
416 /* check server address and port */
417 if (ip_addr_cmp(addr, &sntp_last_server_address) &&
418 (port == SNTP_PORT))
419#else /* SNTP_CHECK_RESPONSE >= 1 */
420 LWIP_UNUSED_ARG(addr);
421 LWIP_UNUSED_ARG(port);
422#endif /* SNTP_CHECK_RESPONSE >= 1 */
423 {
424 /* process the response */
425 if (p->tot_len == SNTP_MSG_LEN) {
426 pbuf_copy_partial(p, &mode, 1, SNTP_OFFSET_LI_VN_MODE);
427 mode &= SNTP_MODE_MASK;
428 /* if this is a SNTP response... */
429 if ((mode == SNTP_MODE_SERVER) ||
430 (mode == SNTP_MODE_BROADCAST)) {
431 pbuf_copy_partial(p, &stratum, 1, SNTP_OFFSET_STRATUM);
432 if (stratum == SNTP_STRATUM_KOD) {
433 /* Kiss-of-death packet. Use another server or increase UPDATE_DELAY. */
434 err = SNTP_ERR_KOD;
435 LWIP_DEBUGF(SNTP_DEBUG_STATE, ("sntp_recv: Received Kiss-of-Death\n"));
436 } else {
437#if SNTP_CHECK_RESPONSE >= 2
438 /* check originate_timetamp against sntp_last_timestamp_sent */
439 u32_t originate_timestamp[2];
440 pbuf_copy_partial(p, &originate_timestamp, 8, SNTP_OFFSET_ORIGINATE_TIME);
441 if ((originate_timestamp[0] != sntp_last_timestamp_sent[0]) ||
442 (originate_timestamp[1] != sntp_last_timestamp_sent[1]))
443 {
444 LWIP_DEBUGF(SNTP_DEBUG_WARN, ("sntp_recv: Invalid originate timestamp in response\n"));
445 } else
446#endif /* SNTP_CHECK_RESPONSE >= 2 */
447 /* @todo: add code for SNTP_CHECK_RESPONSE >= 3 and >= 4 here */
448 {
449 /* correct answer */
450 err = ERR_OK;
451 pbuf_copy_partial(p, &receive_timestamp, SNTP_RECEIVE_TIME_SIZE * 4, SNTP_OFFSET_RECEIVE_TIME);
452 }
453 }
454 } else {
455 LWIP_DEBUGF(SNTP_DEBUG_WARN, ("sntp_recv: Invalid mode in response: %"U16_F"\n", (u16_t)mode));
456 }
457 } else {
458 LWIP_DEBUGF(SNTP_DEBUG_WARN, ("sntp_recv: Invalid packet length: %"U16_F"\n", p->tot_len));
459 }
460 }
461 pbuf_free(p);
462 if (err == ERR_OK) {
463 /* Correct response, reset retry timeout */
464 SNTP_RESET_RETRY_TIMEOUT();
465
466 sntp_process(receive_timestamp);
467
468 /* Set up timeout for next request */
469 sys_timeout((u32_t)SNTP_UPDATE_DELAY, sntp_request, NULL);
470 LWIP_DEBUGF(SNTP_DEBUG_STATE, ("sntp_recv: Scheduled next time request: %"U32_F" ms\n",
471 (u32_t)SNTP_UPDATE_DELAY));
472 } else if (err == SNTP_ERR_KOD) {
473 /* Kiss-of-death packet. Use another server or increase UPDATE_DELAY. */
474 sntp_try_next_server(NULL);
475 } else {
476 /* another error, try the same server again */
477 sntp_retry(NULL);
478 }
479}
480
481/** Actually send an sntp request to a server.
482 *
483 * @param server_addr resolved IP address of the SNTP server
484 */
485static void
486sntp_send_request(ip_addr_t *server_addr)
487{
488 struct pbuf* p;
489 p = pbuf_alloc(PBUF_TRANSPORT, SNTP_MSG_LEN, PBUF_RAM);
490 if (p != NULL) {
491 struct sntp_msg *sntpmsg = (struct sntp_msg *)p->payload;
492 LWIP_DEBUGF(SNTP_DEBUG_STATE, ("sntp_send_request: Sending request to server\n"));
493 /* initialize request message */
494 sntp_initialize_request(sntpmsg);
495 /* send request */
496 udp_sendto(sntp_pcb, p, server_addr, SNTP_PORT);
497 /* free the pbuf after sending it */
498 pbuf_free(p);
499 /* set up receive timeout: try next server or retry on timeout */
500 sys_timeout((u32_t)SNTP_RECV_TIMEOUT, sntp_try_next_server, NULL);
501#if SNTP_CHECK_RESPONSE >= 1
502 /* save server address to verify it in sntp_recv */
503 ip_addr_set(&sntp_last_server_address, server_addr);
504#endif /* SNTP_CHECK_RESPONSE >= 1 */
505 } else {
506 LWIP_DEBUGF(SNTP_DEBUG_SERIOUS, ("sntp_send_request: Out of memory, trying again in %"U32_F" ms\n",
507 (u32_t)SNTP_RETRY_TIMEOUT));
508 /* out of memory: set up a timer to send a retry */
509 sys_timeout((u32_t)SNTP_RETRY_TIMEOUT, sntp_request, NULL);
510 }
511}
512
513#if SNTP_SERVER_DNS
514/**
515 * DNS found callback when using DNS names as server address.
516 */
517static void
518sntp_dns_found(const char* hostname, ip_addr_t *ipaddr, void *arg)
519{
520 LWIP_UNUSED_ARG(hostname);
521 LWIP_UNUSED_ARG(arg);
522
523 if (ipaddr != NULL) {
524 /* Address resolved, send request */
525 LWIP_DEBUGF(SNTP_DEBUG_STATE, ("sntp_dns_found: Server address resolved, sending request\n"));
526 sntp_send_request(ipaddr);
527 } else {
528 /* DNS resolving failed -> try another server */
529 LWIP_DEBUGF(SNTP_DEBUG_WARN_STATE, ("sntp_dns_found: Failed to resolve server address resolved, trying next server\n"));
530 sntp_try_next_server(NULL);
531 }
532}
533#endif /* SNTP_SERVER_DNS */
534
535/**
536 * Send out an sntp request.
537 *
538 * @param arg is unused (only necessary to conform to sys_timeout)
539 */
540static void
541sntp_request(void *arg)
542{
543 ip_addr_t sntp_server_address;
544 err_t err;
545
546 LWIP_UNUSED_ARG(arg);
547
548 /* initialize SNTP server address */
549#if SNTP_SERVER_DNS
550 err = dns_gethostbyname(sntp_server_addresses[sntp_current_server], &sntp_server_address,
551 sntp_dns_found, NULL);
552 if (err == ERR_INPROGRESS) {
553 /* DNS request sent, wait for sntp_dns_found being called */
554 LWIP_DEBUGF(SNTP_DEBUG_STATE, ("sntp_request: Waiting for server address to be resolved.\n"));
555 return;
556 }
557#else /* SNTP_SERVER_DNS */
558 err = ipaddr_aton(sntp_server_addresses[sntp_current_server], &sntp_server_address)
559 ? ERR_OK : ERR_ARG;
560
561#endif /* SNTP_SERVER_DNS */
562
563 if (err == ERR_OK) {
564 sntp_send_request(&sntp_server_address);
565 } else {
566 /* address conversion failed, try another server */
567 LWIP_DEBUGF(SNTP_DEBUG_WARN_STATE, ("sntp_request: Invalid server address, trying next server.\n"));
568 sys_timeout((u32_t)SNTP_RETRY_TIMEOUT, sntp_try_next_server, NULL);
569 }
570}
571
572/**
573 * Initialize this module.
574 * Send out request instantly or after SNTP_STARTUP_DELAY.
575 */
576void
577sntp_init(void)
578{
579 if (sntp_pcb == NULL) {
580 SNTP_RESET_RETRY_TIMEOUT();
581 sntp_pcb = udp_new();
582 LWIP_ASSERT("Failed to allocate udp pcb for sntp client", sntp_pcb != NULL);
583 if (sntp_pcb != NULL) {
584 udp_recv(sntp_pcb, sntp_recv, NULL);
585#if SNTP_STARTUP_DELAY
586 sys_timeout((u32_t)SNTP_STARTUP_DELAY, sntp_request, NULL);
587#else
588 sntp_request(NULL);
589#endif
590 }
591 }
592}
593
594/**
595 * Stop this module.
596 */
597void
598sntp_stop(void)
599{
600 if (sntp_pcb != NULL) {
601 sys_untimeout(sntp_request, NULL);
602 udp_remove(sntp_pcb);
603 sntp_pcb = NULL;
604 }
605}
606#endif /* LWIP_UDP */
Note: See TracBrowser for help on using the repository browser.