mongoose/src/sntp.c

70 lines
2.3 KiB
C

#include "sntp.h"
#include "arch.h"
#include "event.h"
#include "log.h"
#include "util.h"
#define SNTP_INTERVAL_SEC 3600
#define SNTP_TIME_OFFSET 2208988800UL
static unsigned long s_sntmp_next;
int64_t mg_sntp_parse(const unsigned char *buf, size_t len) {
int64_t res = -1;
int mode = len > 0 ? buf[0] & 7 : 0;
if (len < 48) {
MG_ERROR(("%s", "corrupt packet"));
} else if ((buf[0] & 0x38) >> 3 != 4) {
MG_ERROR(("%s", "wrong version"));
} else if (mode != 4 && mode != 5) {
MG_ERROR(("%s", "not a server reply"));
} else if (buf[1] == 0) {
MG_ERROR(("%s", "server sent a kiss of death"));
} else {
uint32_t *data = (uint32_t *) &buf[40];
unsigned long seconds = mg_ntohl(data[0]) - SNTP_TIME_OFFSET;
unsigned long useconds = mg_ntohl(data[1]);
// MG_DEBUG(("%lu %lu %lu", time(0), seconds, useconds));
res = ((int64_t) seconds) * 1000 + (int64_t) ((useconds / 1000) % 1000);
s_sntmp_next = seconds + SNTP_INTERVAL_SEC;
}
return res;
}
static void sntp_cb(struct mg_connection *c, int ev, void *evd, void *fnd) {
if (ev == MG_EV_READ) {
int64_t milliseconds = mg_sntp_parse(c->recv.buf, c->recv.len);
if (milliseconds > 0) {
mg_call(c, MG_EV_SNTP_TIME, &milliseconds);
MG_DEBUG(("%u.%u, next at %lu", (unsigned) (milliseconds / 1000),
(unsigned) (milliseconds % 1000), s_sntmp_next));
}
c->recv.len = 0; // Clear receive buffer
} else if (ev == MG_EV_CONNECT) {
mg_sntp_send(c, (unsigned long) time(NULL));
} else if (ev == MG_EV_CLOSE) {
}
(void) fnd;
(void) evd;
}
void mg_sntp_send(struct mg_connection *c, unsigned long utc) {
if (c->is_resolving) {
MG_ERROR(("%lu wait until resolved", c->id));
} else if (utc > s_sntmp_next) {
uint8_t buf[48] = {0};
s_sntmp_next = utc + SNTP_INTERVAL_SEC;
buf[0] = (0 << 6) | (4 << 3) | 3;
mg_send(c, buf, sizeof(buf));
MG_DEBUG(("%lu ct %lu, next at %lu", c->id, utc, s_sntmp_next));
}
}
struct mg_connection *mg_sntp_connect(struct mg_mgr *mgr, const char *url,
mg_event_handler_t fn, void *fnd) {
struct mg_connection *c = NULL;
if (url == NULL) url = "udp://time.google.com:123";
if ((c = mg_connect(mgr, url, fn, fnd)) != NULL) c->pfn = sntp_cb;
return c;
}