| Net::NTP - Perl extension for decoding NTP server responses |
Given a NTP Packet (from B), return the offset to local (A) according to its xmttime(T1) and rectime(T4)
theta = T(B) - T(A) = 1/2 * [(T2-T1) + (T3-T4)]
Return the delay from the sender (B) of $packet given known local xmttime(T1) and rectime(T4)
delta = T(ABA) = (T4-T1) - (T3-T2).
Net::NTP - Perl extension for decoding NTP server responses
use Net::NTP qw(get_ntp_response); use Time::HiRes qw(time); my %response = get_ntp_response();
my $xmttime = time();
my $spkt = Net::NTP::Packet->new_client_packet($xmttime);
$socket->send($pkt->encode());
$socket->recv(my $data, 1024);
my $rectime = time();
my $cpkt = Net::NTP::Packet->decode($data, $xmttime, $rectime);
print "Stratum: ", $cpkt->{stratum}, "\n";
print "Offset: ", Net::NTP->offset($pkt, $xmttime, $rectime), "\n"
All this module does is send a packet to an NTP server and then decode the packet received into it's respective parts - as outlined in RFC5905 (superseding RFC1305 and RFC2030).
This only supports Association Mode 3 (Client).
This module exports a single method (get_ntp_response) and returns an associative array based upon RFC1305 and RFC2030. The response from the server is ``humanized'' to a point that further processing of the information received from the server can be manipulated. For example: timestamps are in epoch, so one could use the localtime function to produce an even more ``human'' representation of the timestamp.
get_ntp_response(<server>, <port>);
This module exports a single method - get_ntp_response. It takes the server as the first argument (localhost is the default) and port to send/recieve the packets (ntp or 123 by default). It returns an associative array of the various parts of the packet as outlined in RFC1305. It ``normalizes'' or ``humanizes'' various parts of the packet. For example: all the timestamps are in epoch, NOT hexidecimal.
Two special fields (Delay and Offset) are calculated and added to
the response.
If there's a timeout or other communications error get_ntp_response will die (so call get_ntp_response in an eval block).
perl, IO::Socket, RFC5905, RFC1305, RFC2030
Now maintained by Ask Bjørn Hansen, <ask@develooper.com
Originally by James G. Willmore, <jwillmore (at) adelphia.net<gt> or <owner (at) ljcomputing.net<gt>
Special thanks to Ralf D. Kloth <ralf (at) qrq.de<gt> for the code to decode NTP packets.
Copyright 2009 by Ask Bjørn Hansen; 2004 by James G. Willmore
This library is free software; you can redistribute it and/or modify it under the same terms as Perl itself.
Net::NTP::Packet
Representation of a NTP Packet with serialization primitives.
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|LI | VN |Mode | Stratum | Poll | Precision |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Root Delay |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Root Dispersion |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Reference ID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
+ Reference Timestamp (64) +
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
+ Origin Timestamp (64) +
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
+ Receive Timestamp (64) +
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
+ Transmit Timestamp (64) +
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
. .
. Extension Field 1 (variable) .
. .
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
. .
. Extension Field 2 (variable) .
. .
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Key Identifier |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
| dgst (128) |
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
=cut
create a new Net::NTP::Packet instance.
Parameters are the field names, gotten from ``7.3. Packet Header Variables''
new_client_packet($xmttime)Make a packet in association mode 'Client' to be sent to a server.
encode()Encode a packet to its wire format. NOTE: It only encodes server packets at the moment.
decode the NTP packet from its wire format.
| Net::NTP - Perl extension for decoding NTP server responses |