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implement Sntp;
#
# rfc1361 (simple network time protocol)
#
include "sys.m";
sys: Sys;
include "draw.m";
include "ip.m";
ip: IP;
IPaddr: import ip;
include "timers.m";
timers: Timers;
Timer: import timers;
include "arg.m";
Sntp: module
{
init: fn(nil: ref Draw->Context, nil: list of string);
};
debug := 0;
Retries: con 4;
Delay: con 3*1000; # milliseconds
SNTP: adt {
li: int;
vn: int;
mode: int;
stratum: int; # level of local clock
poll: int; # log2(maximum interval in seconds between successive messages)
precision: int; # log2(seconds precision of local clock) [eg, -6 for mains, -18 for microsec]
rootdelay: int; # round trip delay in seconds to reference (16:16 fraction)
dispersion: int; # maximum error relative to primary reference
clockid: string; # reference clock identifier
reftime: big; # local time at which clock last set/corrected
orgtime: big; # local time at which client transmitted request
rcvtime: big; # time at which request arrived at server
xmttime: big; # time server transmitted reply
auth: array of byte; # auth field (ignored by this implementation)
new: fn(vn, mode: int): ref SNTP;
pack: fn(s: self ref SNTP): array of byte;
unpack: fn(a: array of byte): ref SNTP;
};
SNTPlen: con 4+3*4+4*8;
Version: con 1; # accepted by version 2 and version 3 servers
Stratum: con 0;
Poll: con 0;
LI: con 0;
Symmetric: con 2;
ClientMode: con 3;
ServerMode: con 4;
Epoch: con big 86400*big (365*70 + 17); # seconds between 1 Jan 1900 and 1 Jan 1970
Microsec: con big 100000;
server := "$ntp";
stderr: ref Sys->FD;
init(nil: ref Draw->Context, args: list of string)
{
sys = load Sys Sys->PATH;
ip = load IP IP->PATH;
timers = load Timers Timers->PATH;
ip->init();
arg := load Arg Arg->PATH;
arg->init(args);
arg->setusage("sntp [-d] [server]");
doset := 1;
while((o := arg->opt()) != 0)
case o {
'd' => debug++;
'i' => doset = 0;
* => arg->usage();
}
args = arg->argv();
if(len args > 1)
arg->usage();
arg = nil;
if(args != nil)
server = hd args;
sys->pctl(Sys->NEWPGRP|Sys->FORKFD, nil);
stderr = sys->fildes(2);
timers->init(100);
(ok, conn) := sys->dial(netmkaddr(server, "udp", "ntp"), nil);
if(ok < 0){
sys->fprint(stderr, "sntp: can't dial %s: %r\n", server);
raise "fail:dial";
}
replies := chan of ref SNTP;
spawn reader(conn.dfd, replies);
for(i:=0; i<Retries; i++){
request := SNTP.new(Version, ClientMode);
request.poll = 6;
request.orgtime = (big time() + Epoch)<<32;
b := request.pack();
if(sys->write(conn.dfd, b, len b) != len b){
sys->fprint(stderr, "sntp: UDP write failed: %r\n");
continue;
}
t := Timer.start(Delay);
alt{
reply := <-replies =>
t.stop();
if(reply == nil)
quit("read error");
if(debug){
sys->fprint(stderr, "LI = %d, version = %d, mode = %d\n", reply.li, reply.vn, reply.mode);
if(reply.stratum == 1)
sys->fprint(stderr, "stratum = 1 (%s), ", reply.clockid);
else
sys->fprint(stderr, "stratum = %d, ", reply.stratum);
sys->fprint(stderr, "poll = %d, prec = %d\n", reply.poll, reply.precision);
sys->fprint(stderr, "rootdelay = %d, dispersion = %d\n", reply.rootdelay, reply.dispersion);
}
if(reply.vn == 0 || reply.vn > 3)
continue; # unsupported version, ignored
if(reply.mode >= 6 || reply.mode == ClientMode)
continue;
now := ((reply.xmttime>>32)&16rFFFFFFFF) - Epoch;
if(now <= big 1120000000)
continue;
if(reply.li == 3 || reply.stratum == 0) # unsynchronised
sys->fprint(stderr, "sntp: time server not synchronised to reference time\n");
if(debug)
sys->print("%bd\n", now);
if(doset){
settime("#r/rtc", now);
settime("/dev/time", now * Microsec);
}
quit(nil);
<-t.timeout =>
continue;
}
}
sys->fprint(sys->fildes(2), "sntp: no response from server %s\n", server);
quit("timeout");
}
reader(fd: ref Sys->FD, replies: chan of ref SNTP)
{
for(;;){
buf := array[512] of byte;
nb := sys->read(fd, buf, len buf);
if(nb <= 0)
break;
reply := SNTP.unpack(buf[0:nb]);
if(reply == nil){
# ignore bad replies
if(debug)
sys->fprint(stderr, "sntp: invalid reply (len %d)\n", nb);
continue;
}
replies <-= reply;
}
if(debug)
sys->fprint(stderr, "sntp: UDP read failed: %r\n");
replies <-= nil;
}
quit(s: string)
{
pid := sys->pctl(0, nil);
timers->shutdown();
fd := sys->open("#p/"+string pid+"/ctl", Sys->OWRITE);
if(fd != nil)
sys->fprint(fd, "killgrp");
if(s != nil)
raise "fail:"+s;
exit;
}
time(): int
{
fd := sys->open("#r/rtctime", Sys->OREAD);
if(fd == nil){
fd = sys->open("/dev/time", Sys->OREAD);
if(fd == nil)
return 0;
}
b := array[128] of byte;
n := sys->read(fd, b, len b);
if(n <= 0)
return 0;
return int (big string b[0:n] / big 1000000);
}
settime(f: string, t: big)
{
fd := sys->open(f, Sys->OWRITE);
if(fd != nil)
sys->fprint(fd, "%bd", t);
}
get8(a: array of byte, i: int): big
{
b := big ip->get4(a, i+4) & 16rFFFFFFFF;
return (big ip->get4(a, i) << 32) | b;
}
put8(a: array of byte, o: int, v: big)
{
ip->put4(a, o, int (v>>32));
ip->put4(a, o+4, int v);
}
SNTP.unpack(a: array of byte): ref SNTP
{
if(len a < SNTPlen)
return nil;
s := ref SNTP;
mode := int a[0];
s.li = mode>>6;
s.vn = (mode>>3);
s.mode = mode & 3;
s.stratum = int a[1];
s.poll = int a[2];
if(s.poll & 16r80)
s.poll |= ~0 << 8;
s.precision = int a[3];
if(s.precision & 16r80)
s.precision |= ~0 << 8;
s.rootdelay = ip->get4(a, 4);
s.dispersion = ip->get4(a, 8);
if(s.stratum <= 1){
for(i := 12; i < 16; i++)
if(a[i] == byte 0)
break;
s.clockid = string a[12:i];
}else
s.clockid = sys->sprint("%d.%d.%d.%d", int a[12], int a[13], int a[14], int a[15]);
s.reftime = get8(a, 16);
s.orgtime = get8(a, 24);
s.rcvtime = get8(a, 32);
s.xmttime = get8(a, 40);
if(len a > SNTPlen)
s.auth = a[48:];
return s;
}
SNTP.pack(s: self ref SNTP): array of byte
{
a := array[SNTPlen + len s.auth] of byte;
a[0] = byte ((s.li<<6) | (s.vn<<3) | s.mode);
a[1] = byte s.stratum;
a[2] = byte s.poll;
a[3] = byte s.precision;
ip->put4(a, 4, s.rootdelay);
ip->put4(a, 8, s.dispersion);
ip->put4(a, 12, 0); # clockid field
if(s.clockid != nil){
if(s.stratum <= 1){
b := array of byte s.clockid;
for(i := 0; i < len b && i < 4; i++)
a[12+i] = b[i];
}else
a[12:] = IPaddr.parse(s.clockid).t1.v4();
}
put8(a, 16, s.reftime);
put8(a, 24, s.orgtime);
put8(a, 32, s.rcvtime);
put8(a, 40, s.xmttime);
if(s.auth != nil)
a[48:] = s.auth;
return a;
}
SNTP.new(vn, mode: int): ref SNTP
{
s := ref SNTP;
s.vn = vn;
s.mode = mode;
s.li = 0;
s.stratum = 0;
s.poll = 0;
s.precision = 0;
s.clockid = nil;
s.reftime = big 0;
s.orgtime = big 0;
s.rcvtime = big 0;
s.xmttime = big 0;
return s;
}
netmkaddr(addr, net, svc: string): string
{
if(net == nil)
net = "net";
(n, nil) := sys->tokenize(addr, "!");
if(n <= 1){
if(svc== nil)
return sys->sprint("%s!%s", net, addr);
return sys->sprint("%s!%s!%s", net, addr, svc);
}
if(svc == nil || n > 2)
return addr;
return sys->sprint("%s!%s", addr, svc);
}
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