ntp_service.cpp

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// Copyright (C) 2026 Douglas Quigg (dstroy0) <dquigg123@gmail.com>
// SPDX-License-Identifier: AGPL-3.0-or-later
 
/**
 * @file ntp_service.cpp
 * @brief SNTP wall-clock time sync implementation (DETWS_ENABLE_NTP).
 */
 
#include "ntp_service.h"
#include "shared_primitives/http_date.h" // detws_http_date() - the shared IMF-fixdate formatter
 
#if DETWS_ENABLE_NTP && defined(ARDUINO)
 
#include <Arduino.h>
 
// A successful sync moves the clock well past this sentinel (2021-01-01 UTC);
// a cold-booted RTC sits near the Unix epoch.
static const time_t DETWS_NTP_PLAUSIBLE_EPOCH = 1609459200;
 
bool detws_ntp_begin(const char *tz, const char *server1, const char *server2)
{
    // configTzTime applies the POSIX TZ and starts the SNTP client (async).
    configTzTime(tz ? tz : "UTC0", server1, server2);
    return true;
}
 
bool detws_ntp_synced()
{
    return time(nullptr) > DETWS_NTP_PLAUSIBLE_EPOCH;
}
 
time_t detws_ntp_epoch()
{
    time_t now = time(nullptr);
    return (now > DETWS_NTP_PLAUSIBLE_EPOCH) ? now : 0;
}
 
size_t detws_ntp_http_date(char *out, size_t out_cap)
{
    return detws_http_date(detws_ntp_epoch(), out, out_cap);
}
 
#else
 
// Host build: no SNTP. A test seam lets a unit test inject a wall-clock epoch so
// the Date-header path (and any time-dependent code) is exercisable off-device.
#include <time.h>
// All host NTP test-seam state, owned by one instance (internal linkage): the injected
// wall-clock epoch, so it is one named owner, unreachable from any other translation unit.
namespace
{
struct NtpSvcCtx
{
    time_t host_test_epoch = 0;
};
NtpSvcCtx s_ntp_svc;
} // namespace
void detws_ntp_set_test_epoch(time_t epoch)
{
    s_ntp_svc.host_test_epoch = epoch;
}
 
bool detws_ntp_begin(const char *tz, const char *server1, const char *server2)
{
    (void)tz;
    (void)server1;
    (void)server2;
    return false;
}
bool detws_ntp_synced()
{
    return s_ntp_svc.host_test_epoch != 0;
}
time_t detws_ntp_epoch()
{
    return s_ntp_svc.host_test_epoch;
}
size_t detws_ntp_http_date(char *out, size_t out_cap)
{
    return detws_http_date(detws_ntp_epoch(), out, out_cap);
}
 
#endif // DETWS_ENABLE_NTP && ARDUINO
 
// NTP as a registry time source (defined for both the device and host builds; detws_ntp_epoch is 0
// until synced / when no test epoch is injected). Register it with detws_time_source_add() so the
// aggregated detws_time_now() - and the HTTP Date header - can be fed by NTP alongside an RTC / GPS.
uint32_t ntp_time_source(void)
{
    return (uint32_t)detws_ntp_epoch();
}