53 lines
1.8 KiB
C
53 lines
1.8 KiB
C
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// Copyright (c) 2022 Cesanta Software Limited
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// All rights reserved
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//
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// Synchronize time with remote SNTP server
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// A working time() call is required by TLS, so an embedded device without
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// a clock that wants to use TLS, must sync time via SNTP.
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#include "mongoose.h"
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// The UNIX epoch of the boot time. Initially, we set it to 0. But then after
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// SNTP response, we update it to the correct value, which will allow us to
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// use time(). Uptime in milliseconds is returned by mg_millis().
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static time_t s_boot_timestamp = 0;
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// SNTP client connection
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static struct mg_connection *s_sntp_conn = NULL;
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// On embedded systems, rename to time()
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time_t my_time(time_t *tp) {
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time_t t = s_boot_timestamp + mg_millis() / 1000;
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if (tp != NULL) *tp = t;
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return t;
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}
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// SNTP client callback
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static void sfn(struct mg_connection *c, int ev, void *ev_data, void *fn_data) {
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if (ev == MG_EV_SNTP_TIME) {
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int64_t t = *(int64_t *) ev_data;
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MG_INFO(("Got SNTP time: %lld ms from epoch", t));
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s_boot_timestamp = (time_t) ((t - mg_millis()) / 1000);
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} else if (ev == MG_EV_CLOSE) {
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s_sntp_conn = NULL;
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}
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(void) fn_data, (void) c;
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}
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// Called every 5 seconds. Increase that for production case.
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static void timer_fn(void *arg) {
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struct mg_mgr *mgr = (struct mg_mgr *) arg;
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if (s_sntp_conn == NULL) s_sntp_conn = mg_sntp_connect(mgr, NULL, sfn, NULL);
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if (s_sntp_conn != NULL) mg_sntp_request(s_sntp_conn);
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}
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int main(void) {
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struct mg_mgr mgr; // Event manager
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mg_mgr_init(&mgr); // Initialise event manager
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mg_log_set(MG_LL_DEBUG); // Set log level
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mg_timer_add(&mgr, 5000, MG_TIMER_REPEAT | MG_TIMER_RUN_NOW, timer_fn, &mgr);
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for (;;) mg_mgr_poll(&mgr, 300); // Infinite event loop
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mg_mgr_free(&mgr); // Free manager resources
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return 0;
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}
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