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/*
* ntp_client.c
*
* Copyright © 2023 Thomas White <taw@physics.org>
*
* This file is part of MorningTown
*
* Based on pico-examples/pico_w/ntp_client/picow_ntp_client.c
* Original license: BSD-3-Clause
* Copyright (c) 2022 Raspberry Pi (Trading) Ltd.
*
* MorningTown is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* MorningTown is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with MorningTown. If not, see <http://www.gnu.org/licenses/>.
*
*/
#include <string.h>
#include <time.h>
#include <hardware/rtc.h>
#include <pico/stdlib.h>
#include <pico/util/datetime.h>
#include <pico/cyw43_arch.h>
#include "lwip/dns.h"
#include "lwip/pbuf.h"
#include "lwip/udp.h"
#include "ntp_client.h"
typedef struct NTP_T_ {
ip_addr_t ntp_server_address;
bool dns_request_sent;
struct udp_pcb *ntp_pcb;
alarm_id_t ntp_resend_alarm;
void (*callback)(int status);
} NTP_T;
#define NTP_SERVER "pool.ntp.org"
#define NTP_MSG_LEN 48
#define NTP_PORT 123
#define NTP_DELTA 2208988800 // seconds between 1 Jan 1900 and 1 Jan 1970
#define NTP_RESEND_TIME (10 * 1000)
static void set_rtc(time_t iutc)
{
time_t tv = iutc + UTC_OFFSET_SEC;
struct tm *utc = gmtime(&tv);
datetime_t t;
t.year = utc->tm_year + 1900;
t.month = utc->tm_mon + 1;
t.day = utc->tm_mday;
t.dotw = utc->tm_wday;
t.hour = utc->tm_hour;
t.min = utc->tm_min;
t.sec = utc->tm_sec;
debug_print("time is %i/%i/%i %i %i:%i:%i\n",
t.year, t.month, t.day, t.dotw, t.hour, t.min, t.sec);
rtc_set_datetime(&t);
}
static void ntp_result(NTP_T *state, int status, time_t *result)
{
debug_print("NTP result:\n");
if (status == NTP_REPLY_RECEIVED && result) {
debug_print("yay!\n");
if ( state->ntp_resend_alarm > 0 ) {
cancel_alarm(state->ntp_resend_alarm);
state->ntp_resend_alarm = 0;
}
set_rtc(*result);
} else {
debug_print("other reply.\n");
}
state->callback(status);
state->dns_request_sent = false;
}
static void ntp_request(NTP_T *state)
{
debug_print("sending NTP UDP\n");
cyw43_arch_lwip_begin();
struct pbuf *p = pbuf_alloc(PBUF_TRANSPORT, NTP_MSG_LEN, PBUF_RAM);
uint8_t *req = (uint8_t *) p->payload;
memset(req, 0, NTP_MSG_LEN);
req[0] = 0x1b;
udp_sendto(state->ntp_pcb, p, &state->ntp_server_address, NTP_PORT);
pbuf_free(p);
cyw43_arch_lwip_end();
state->callback(NTP_REQUEST_SENT);
}
static void ntp_dns_found(const char *hostname,
const ip_addr_t *ipaddr,
void *arg)
{
NTP_T *state = (NTP_T*)arg;
if (ipaddr) {
debug_print("DNS ok (%i)\n", *ipaddr);
state->ntp_server_address = *ipaddr;
ntp_request(state);
} else {
debug_print("NTP failed: DNS no address\n");
ntp_result(state, NTP_DNS_NO_ADDR, NULL);
}
}
static void ntp_recv(void *arg, struct udp_pcb *pcb, struct pbuf *p,
const ip_addr_t *addr, u16_t port)
{
NTP_T *state = (NTP_T*)arg;
uint8_t mode = pbuf_get_at(p, 0) & 0x7;
uint8_t stratum = pbuf_get_at(p, 1);
debug_print("got UDP: %i %i\n", addr, state->ntp_server_address);
debug_print("port %i len %i mode %i stratum %i\n", port, p->tot_len, mode, stratum);
if (ip_addr_cmp(addr, &state->ntp_server_address)
&& port == NTP_PORT
&& p->tot_len == NTP_MSG_LEN
&& mode == 0x4 && stratum != 0)
{
uint8_t seconds_buf[4] = {0};
pbuf_copy_partial(p, seconds_buf, sizeof(seconds_buf), 40);
uint32_t seconds_since_1900 = seconds_buf[0] << 24
| seconds_buf[1] << 16
| seconds_buf[2] << 8
| seconds_buf[3];
uint32_t seconds_since_1970 = seconds_since_1900 - NTP_DELTA;
time_t epoch = seconds_since_1970;
debug_print("second since 1970 = %i\n", epoch);
ntp_result(state, NTP_REPLY_RECEIVED, &epoch);
} else {
ntp_result(state, NTP_BAD_REPLY, NULL);
}
pbuf_free(p);
}
static int64_t ntp_failed_handler(alarm_id_t id, void *user_data)
{
NTP_T *state = (NTP_T*)user_data;
ntp_result(state, NTP_TIMEOUT, NULL);
return 0;
}
NTP_T *ntp_init(void (*reply_func)(int))
{
NTP_T *state = calloc(1, sizeof(NTP_T));
if (!state) return NULL;
state->callback = reply_func;
state->ntp_pcb = udp_new_ip_type(IPADDR_TYPE_ANY);
if (!state->ntp_pcb) {
free(state);
return NULL;
}
udp_recv(state->ntp_pcb, ntp_recv, state);
return state;
}
void ntp_send_request(NTP_T *state)
{
if ( state == NULL ) return;
cyw43_arch_lwip_begin();
int err = dns_gethostbyname(NTP_SERVER,
&state->ntp_server_address,
ntp_dns_found,
state);
cyw43_arch_lwip_end();
state->ntp_resend_alarm = add_alarm_in_ms(NTP_RESEND_TIME,
ntp_failed_handler,
state,
true);
state->dns_request_sent = true;
if ( err == ERR_OK ) {
/* Immediate reply -> cached result */
ntp_request(state);
} else if (err != ERR_INPROGRESS) {
/* Error sending DNS request
* (ERR_INPROGRESS means expect a callback) */
ntp_result(state, NTP_DNS_ERROR, NULL);
}
}
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