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-rw-r--r--toys/pending/sntp.c236
1 files changed, 145 insertions, 91 deletions
diff --git a/toys/pending/sntp.c b/toys/pending/sntp.c
index 057a30b6..b85b9dce 100644
--- a/toys/pending/sntp.c
+++ b/toys/pending/sntp.c
@@ -6,21 +6,13 @@
modes: oneshot display, oneshot set, persist, serve, multi
- verify source addr
- serve time
- - precision -6
- - source LOCL
- - copy source packet transmit to originate (5->3), 2=4=5
- wait for multicast updates
- uniclient: retry at poll interval
-
-USE_SNTP(NEWTOY(sntp, "m:Sp:asdD[!as]", TOYFLAG_USR|TOYFLAG_BIN))
+USE_SNTP(NEWTOY(sntp, "m:Sp:asdDqr#<4>17=10[!as]", TOYFLAG_USR|TOYFLAG_BIN))
config SNTP
bool "sntp"
default n
help
- usage: sntp [-saS] [-dD[-m ADDRESS] [-p PORT] [SERVER]
+ usage: sntp [-saSdDqm] [-r SHIFT] [-m ADDRESS] [-p PORT] [SERVER]
Simple Network Time Protocol client. Query SERVER and display time.
@@ -31,12 +23,15 @@ config SNTP
-m Wait for updates from multicast ADDRESS (RFC 4330 says use 224.0.1.1)
-d Daemonize (run in background re-querying )
-D Daemonize but stay in foreground: re-query time every 1000 seconds
+ -r Retry shift (every 1<<SHIFT seconds)
+ -q Quiet (don't display time)
*/
#define FOR_sntp
#include "toys.h"
GLOBALS(
+ long r;
char *p, *m;
)
@@ -67,14 +62,30 @@ int xrecvwait(int fd, char *buf, int len, union socksaddr *sa, int timeout)
return len;
}
+// Adjust timespec by nanosecond offset
+static void nanomove(struct timespec *ts, long long offset)
+{
+ long long nano = ts->tv_nsec + offset, secs = nano/1000000000;
+
+ ts->tv_sec += secs;
+ nano %= 1000000000;
+ if (nano<0) {
+ ts->tv_sec--;
+ nano += 1000000000;
+ }
+ ts->tv_nsec = nano;
+}
+
// Get time and return ntptime (saving timespec in pointer if not null)
// NTP time is high 32 bits = seconds since 1970 (blame RFC 868), low 32 bits
// fraction of a second.
-static unsigned long long lunchtime(struct timespec *television)
+// diff is how far off we think our clock is from reality (in nanoseconds)
+static unsigned long long lunchtime(struct timespec *television, long long diff)
{
struct timespec tv;
clock_gettime(CLOCK_REALTIME, &tv);
+ if (diff) nanomove(&tv, diff);
if (television) *television = tv;
@@ -99,37 +110,11 @@ static long long nanodiff(struct timespec *old, struct timespec *new)
return (new->tv_sec - old->tv_sec)*1000000000LL+(new->tv_nsec - old->tv_nsec);
}
-// Adjust timespec by nanosecond offset
-static void nanomove(struct timespec *ts, long long offset)
-{
- long long nano = ts->tv_nsec + offset, secs = nano/1000000000;
-
- ts->tv_sec += secs;
- nano %= 1000000000;
- if (nano<0) {
- ts->tv_sec--;
- nano += 1000000000;
- }
- ts->tv_nsec = nano;
-}
-
-static void server_packet(char *buf, unsigned long long ref)
-{
- *buf = 0x24;
- buf[1] = 3;
- buf[2] = 10;
- buf[3] = 253;
- strcpy(buf+12, "LOCL");
- pktime[3] = ref;
- pktime[2] = pktime[4] = pktime[5] = newtime;
-}
-
void sntp_main(void)
{
struct timespec tv, tv2;
unsigned long long *pktime = (void *)toybuf, now, then, before;
- long long diff;
- long diffsecs, diffnano;
+ long long diff = 0;
struct addrinfo *ai;
union socksaddr sa;
int fd, tries = 0;
@@ -142,7 +127,7 @@ void sntp_main(void)
ai = xgetaddrinfo(*toys.optargs, TT.p, AF_UNSPEC, SOCK_DGRAM, IPPROTO_UDP,
AI_PASSIVE*!*toys.optargs);
- if (FLAG(d)) daemon(0,0);
+ if (FLAG(d) && daemon(0, 0)) perror_exit("daemonize");
// Act as server if necessary
if (FLAG(S)|FLAG(m)) {
@@ -152,65 +137,134 @@ void sntp_main(void)
// subscribe to multicast group
memset(&group, 0, sizeof(group));
- group.imr_multiaddr.s_addr = inet_addr(addr);
- xsetsockopt(fd, IPPROTO_IP, IP_ADD_MEMBERSHIP, (void *)&group,
- sizeof(group));
+ group.imr_multiaddr.s_addr = inet_addr(TT.m);
+ xsetsockopt(fd, IPPROTO_IP, IP_ADD_MEMBERSHIP, &group, sizeof(group));
}
} else fd = xsocket(ai->ai_family, SOCK_DGRAM, IPPROTO_UDP);
-// Sm - loop waiting for input
-// Dd - loop polling with probe
-// else poll 3 times
-// if SmDd loop
+ // -Sm = loop waiting for input
+ // -Dd = loop polling time and waiting until next poll period
+ // Otherwise poll up to 3 times to get 2 responses, then exit
+ // loop sending/receiving packets
for (;;) {
+ // Figure out if we're in server and multicast modes don't poll
+ if (FLAG(m) || FLAG(S)) then = -1;
+
+ // daemon and oneshot modes send a packet each time through outer loop
+ else {
+ then = (now = millitime()) + 4000;
+
+ if (FLAG(d) || FLAG(D)) then = now + (1<<TT.r)*1000;
+
+ // Prepare outgoing NTP packet
+ memset(toybuf, 0, 48);
+ *toybuf = 0xe3; // li = 3 (unsynchronized), version = 4, mode = 3 (client)
+ toybuf[2] = 8; // poll frequency 1<<8 = 256 seconds
+ pktime[5] = SWAP_BE64(before = lunchtime(&tv, diff));
+
+ // Send packet
+ xsendto(fd, toybuf, 48, ai->ai_addr);
+ }
+
+ // Loop receiving packets until it's time to send the next one.
+ while (then>0 && now<then) {
+ int strike;
+
+ // Wait to receive a packet
- // Daemon mode isn't limited to 3 tries
- if (FLAG(d) || FLAG(D)) {
- then = retry_timeout;
- } else if (++tries>3) break;
-
- // Prepare outgoing NTP packet
- memset(toybuf, 0, 48);
- *toybuf = 0xe3; // li = 3 (unsynchronized), version = 4, mode = 3 (client)
- toybuf[2] = 8; // poll frequency 1<<8 = 256 seconds
- pktime[5] = SWAP_BE64(before = lunchtime(&tv));
-
- // Send and ye shall receive
- xsendto(fd, toybuf, 48, ai->ai_addr);
- then = (now = millitime())+4000;
- while (now<then) {
- // TODO: confirm sa matches
- if (48 == xrecvwait(fd, toybuf, sizeof(toybuf), &sa, then-now)) {
- if (TT.m || pktime[3] == SWAP_BE64(before)) break;
- }
now = millitime();
+ strike = xrecvwait(fd, toybuf, sizeof(toybuf), &sa, then-now);
+ if (strike<1) {
+ if (!(FLAG(S)||FLAG(m)||FLAG(D)||FLAG(d)) && ++tries>3)
+ error_exit("no reply from %s", *toys.optargs);
+ break;
+ }
+ if (strike<48) continue;
+
+ // Validate packet
+ if (!FLAG(S) || FLAG(m)) {
+ char buf[128];
+ int mode = 7&*toybuf;
+
+ // Is source address what we expect?
+ xstrncpy(buf, ntop(ai->ai_addr), 128);
+ strike = strcmp(buf, ntop((void *)&sa));
+ // Does this reply's orignate timestamp match the packet we sent?
+ if (!FLAG(S) && !FLAG(m) && before != SWAP_BE64(pktime[3])) continue;
+ // Ignore packets from wrong address or with wrong mode
+ if (strike && !FLAG(S)) continue;
+ if (!(FLAG(m) && mode==5 || FLAG(S) && mode==3 ||
+ !FLAG(m) && !FLAG(S) && mode==4)) continue;
+ }
+
+ // If received a -S request packet, send server packet
+ if (strike) {
+ char *buf = toybuf+48;
+
+ *buf = 0x24; // LI 0 VN 4 mode 4.
+ buf[1] = 3; // stratum 3
+ buf[2] = 10; // recommended retry every 1<<10=1024 seconds
+ buf[3] = 250; // precision -6, minimum allowed
+ strcpy(buf+12, "LOCL");
+ pktime[6+3] = pktime[5]; // send back reference time they sent us
+ // everything else is current time
+ pktime[6+2] = pktime[6+4] = pktime[6+5] = lunchtime(0, 0);
+ xsendto(fd, toybuf, 48, (void *)&sa);
+
+ // Got a time packet from a recognized server
+ } else {
+ int unset = !diff;
+
+ // First packet: figure out how far off our clock is from what server
+ // said and try again. Don't set clock, just record offset to use
+ // generating second reuest. (We know this time is in the past
+ // because transmission took time, but it's a start. And if time is
+ // miraculously exact, don't loop.)
+
+ lunchtime(&tv2, diff);
+ diff = nanodiff(&tv, &tv2);
+ if (unset && diff) break;
+
+ // Second packet: determine midpoint of packet transit time according
+ // to local clock, assuming each direction took same time so midpoint
+ // is time server reported. The first television was the adjusted time
+ // we sent the packet at, tv2 is what server replied, so now diff
+ // is round trip time.
+
+ // What time did the server say and how far off are we?
+ nanomove(&tv, diff/2);
+ doublyso(SWAP_BE64(pktime[5]), &tv2);
+ diff = nanodiff(&tv, &tv2);
+
+ if (FLAG(s)) {
+ // Do read/adjust/set to lose as little time as possible.
+ clock_gettime(CLOCK_REALTIME, &tv2);
+ nanomove(&tv2, diff);
+ if (clock_settime(CLOCK_REALTIME, &tv2))
+ perror_exit("clock_settime");
+ } else if (FLAG(a)) {
+ struct timeval why;
+
+ // call adjtime() to move the clock gradually, copying nanoseconds
+ // into gratuitous microseconds structure for sad historical reasons
+ memset(&tv2, 0, sizeof(tv2));
+ nanomove(&tv2, diff);
+ why.tv_sec = tv2.tv_sec;
+ why.tv_usec = tv2.tv_nsec/1000;
+ if (adjtime(&why, 0)) perror_exit("adjtime");
+ }
+
+ // Display the time and offset
+ if (!FLAG(q)) {
+ format_iso_time(toybuf, sizeof(toybuf)-1, &tv2);
+ printf("%s offset %c%d.%09d secs\n", toybuf, (diff<0) ? '-' : '+',
+ abs(diff/1000000000), abs(diff%1000000000));
+ }
+
+ // If we're not in daemon mode, we're done. (Can't get here for -S.)
+ if (!FLAG(d) && !FLAG(D)) return;
+ }
}
- if (now < then) break;
- }
- lunchtime(&tv2);
-
- // determine midpoint of packet transit time according to local clock
- // (simple calculation: assume each direction took same time so midpoint
- // is time reported by other clock)
- diff = nanodiff(&tv, &tv2)/2;
- nanomove(&tv, diff);
-
- doublyso(SWAP_BE64(pktime[5]), &tv2);
- diff = nanodiff(&tv, &tv2);
- diffsecs = diff/1000000000;
- diffnano = diff%1000000000;
- if (FLAG(s)) {
- clock_gettime(CLOCK_REALTIME, &tv);
- nanomove(&tv, diff);
- if (clock_settime(CLOCK_REALTIME, &tv)) perror_exit("clock_settime");
- } else if (FLAG(a)) {
- struct timeval tv = {diffsecs, diffnano/1000};
-
- if (adjtime(&tv, 0)) perror_exit("adjtime");
- } else {
- format_iso_time(toybuf, sizeof(toybuf)-1, &tv2);
- printf("%s offset %c%d.%09d secs\n", toybuf, (diff<0) ? '-' : '+',
- abs(diffsecs), abs(diffnano));
}
}
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