493 lines
15 KiB
Rust
493 lines
15 KiB
Rust
// Copyright (C) 2017 Miroslav Lichvar
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//
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// This program is free software; you can redistribute it and/or modify
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// it under the terms of the GNU General Public License as published by
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// the Free Software Foundation; either version 2 of the License, or
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// (at your option) any later version.
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//
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// This program is distributed in the hope that it will be useful,
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// but WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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// GNU General Public License for more details.
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//
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// You should have received a copy of the GNU General Public License
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// along with this program. If not, see <http://www.gnu.org/licenses/>.
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extern crate byteorder;
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extern crate getopts;
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extern crate net2;
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extern crate rand;
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extern crate privdrop;
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use std::thread;
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use std::env;
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use std::io;
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use std::io::{Error, ErrorKind};
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use std::net::{UdpSocket, SocketAddr};
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use std::time::{SystemTime, Duration};
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use std::sync::{Arc, Mutex};
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use byteorder::{BigEndian, ByteOrder};
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use getopts::Options;
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use net2::UdpBuilder;
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use net2::unix::UnixUdpBuilderExt;
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use rand::random;
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#[derive(Debug, Copy, Clone)]
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struct NtpTimestamp {
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ts: u64,
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}
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impl NtpTimestamp {
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fn now() -> NtpTimestamp {
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let now = SystemTime::now();
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let dur = now.duration_since(std::time::UNIX_EPOCH).unwrap();
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let secs = dur.as_secs() + 2208988800; // 1900 epoch
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let nanos = dur.subsec_nanos();
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NtpTimestamp{ts: (secs << 32) + (nanos as f64 * 4.294967296) as u64}
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}
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fn zero() -> NtpTimestamp {
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NtpTimestamp{ts: 0}
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}
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fn random() -> NtpTimestamp {
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NtpTimestamp{ts: random()}
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}
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fn diff_to_sec(&self, ts: &NtpTimestamp) -> f64 {
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(self.ts - ts.ts) as i64 as f64 / 4294967296.0
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}
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fn read(buf: &[u8]) -> NtpTimestamp {
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NtpTimestamp{ts: BigEndian::read_u64(buf)}
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}
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fn write(&self, buf: &mut [u8]) {
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BigEndian::write_u64(buf, self.ts);
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}
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}
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impl PartialEq for NtpTimestamp {
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fn eq(&self, other: &NtpTimestamp) -> bool {
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self.ts == other.ts
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}
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}
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#[derive(Debug, Copy, Clone)]
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struct NtpFracValue {
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val: u32,
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}
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impl NtpFracValue {
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fn read(buf: &[u8]) -> NtpFracValue {
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NtpFracValue{val: BigEndian::read_u32(buf)}
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}
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fn write(&self, buf: &mut [u8]) {
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BigEndian::write_u32(buf, self.val);
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}
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fn zero() -> NtpFracValue {
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NtpFracValue{val: 0}
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}
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fn increment(&mut self) {
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self.val += 1;
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}
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}
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#[derive(Debug)]
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struct NtpPacket {
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remote_addr: SocketAddr,
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local_ts: NtpTimestamp,
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leap: u8,
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version: u8,
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mode: u8,
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stratum: u8,
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poll: i8,
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precision: i8,
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delay: NtpFracValue,
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dispersion: NtpFracValue,
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ref_id: u32,
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ref_ts: NtpTimestamp,
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orig_ts: NtpTimestamp,
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rx_ts: NtpTimestamp,
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tx_ts: NtpTimestamp,
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}
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impl NtpPacket {
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fn receive(socket: &UdpSocket) -> io::Result<NtpPacket> {
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let mut buf = [0; 1024];
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let (len, addr) = socket.recv_from(&mut buf)?;
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let local_ts = NtpTimestamp::now();
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if len < 48 {
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return Err(Error::new(ErrorKind::UnexpectedEof, "Packet too short"));
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}
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let leap = buf[0] >> 6;
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let version = (buf[0] >> 3) & 0x7;
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let mode = buf[0] & 0x7;
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if version < 1 || version > 4 {
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return Err(Error::new(ErrorKind::Other, "Unsupported version"));
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}
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Ok(NtpPacket{
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remote_addr: addr,
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local_ts: local_ts,
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leap: leap,
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version: version,
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mode: mode,
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stratum: buf[1],
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poll: buf[2] as i8,
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precision: buf[3] as i8,
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delay: NtpFracValue::read(&buf[4..8]),
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dispersion: NtpFracValue::read(&buf[8..12]),
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ref_id: BigEndian::read_u32(&buf[12..16]),
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ref_ts: NtpTimestamp::read(&buf[16..24]),
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orig_ts: NtpTimestamp::read(&buf[24..32]),
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rx_ts: NtpTimestamp::read(&buf[32..40]),
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tx_ts: NtpTimestamp::read(&buf[40..48]),
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})
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}
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fn send(&self, socket: &UdpSocket) -> io::Result<usize> {
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let mut buf = [0; 48];
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buf[0] = self.leap << 6 | self.version << 3 | self.mode;
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buf[1] = self.stratum;
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buf[2] = self.poll as u8;
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buf[3] = self.precision as u8;
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self.delay.write(&mut buf[4..8]);
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self.dispersion.write(&mut buf[8..12]);
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BigEndian::write_u32(&mut buf[12..16], self.ref_id);
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self.ref_ts.write(&mut buf[16..24]);
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self.orig_ts.write(&mut buf[24..32]);
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self.rx_ts.write(&mut buf[32..40]);
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self.tx_ts.write(&mut buf[40..48]);
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socket.send_to(&buf, self.remote_addr)
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}
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fn is_request(&self) -> bool {
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self.mode == 1 || self.mode == 3 ||
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(self.mode == 0 && self.version == 1 && self.remote_addr.port() != 123)
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}
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fn make_response(&self, state: &NtpServerState) -> Option<NtpPacket> {
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if !self.is_request() {
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return None;
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}
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Some(NtpPacket{
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remote_addr: self.remote_addr,
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local_ts: NtpTimestamp::zero(),
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leap: state.leap,
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version: self.version,
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mode: if self.mode == 1 { 2 } else { 4 },
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stratum: state.stratum,
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poll: self.poll,
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precision: state.precision,
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delay: state.delay,
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dispersion: state.dispersion,
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ref_id: state.ref_id,
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ref_ts: state.ref_ts,
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orig_ts: self.tx_ts,
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rx_ts: self.local_ts,
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tx_ts: NtpTimestamp::now(),
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})
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}
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fn new_request(remote_addr: SocketAddr) -> NtpPacket {
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NtpPacket{
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remote_addr: remote_addr,
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local_ts: NtpTimestamp::now(),
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leap: 0,
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version: 4,
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mode: 3,
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stratum: 0,
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poll: 0,
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precision: 0,
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delay: NtpFracValue::zero(),
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dispersion: NtpFracValue::zero(),
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ref_id: 0,
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ref_ts: NtpTimestamp::zero(),
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orig_ts: NtpTimestamp::zero(),
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rx_ts: NtpTimestamp::zero(),
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tx_ts: NtpTimestamp::random(),
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}
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}
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fn is_valid_response(&self, request: &NtpPacket) -> bool {
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self.remote_addr == request.remote_addr &&
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self.mode == request.mode + 1 &&
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self.orig_ts == request.tx_ts
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}
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fn get_server_state(&self) -> NtpServerState {
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NtpServerState{
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leap: self.leap,
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stratum: self.stratum,
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precision: self.precision,
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ref_id: self.ref_id,
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ref_ts: self.ref_ts,
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dispersion: self.dispersion,
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delay: self.delay,
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}
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}
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}
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#[derive(Copy, Clone)]
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struct NtpServerState {
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leap: u8,
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stratum: u8,
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precision: i8,
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ref_id: u32,
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ref_ts: NtpTimestamp,
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dispersion: NtpFracValue,
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delay: NtpFracValue,
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}
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struct NtpServer {
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state: Arc<Mutex<NtpServerState>>,
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sockets: Vec<UdpSocket>,
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server_addr: String,
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debug: bool,
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}
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impl NtpServer {
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fn new(local_addrs: Vec<String>, server_addr: String, debug: bool) -> NtpServer {
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let state = NtpServerState{
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leap: 0,
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stratum: 0,
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precision: 0,
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ref_id: 0,
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ref_ts: NtpTimestamp::zero(),
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dispersion: NtpFracValue::zero(),
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delay: NtpFracValue::zero(),
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};
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let mut sockets = vec![];
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for addr in local_addrs {
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let sockaddr = addr.parse().unwrap();
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let udp_builder = match sockaddr {
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SocketAddr::V4(_) => UdpBuilder::new_v4().unwrap(),
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SocketAddr::V6(_) => UdpBuilder::new_v6().unwrap(),
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};
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let udp_builder_ref = match sockaddr {
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SocketAddr::V4(_) => &udp_builder,
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SocketAddr::V6(_) => udp_builder.only_v6(true).unwrap(),
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};
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let socket = match udp_builder_ref.reuse_port(true).unwrap().bind(sockaddr) {
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Ok(s) => s,
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Err(e) => panic!("Couldn't bind socket: {}", e)
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};
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sockets.push(socket);
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}
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NtpServer{
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state: Arc::new(Mutex::new(state)),
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sockets: sockets,
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server_addr: server_addr,
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debug: debug,
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}
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}
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fn process_requests(thread_id: u32, debug: bool, socket: UdpSocket, state: Arc<Mutex<NtpServerState>>) {
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let mut last_update = NtpTimestamp::now();
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let mut cached_state: NtpServerState;
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cached_state = *state.lock().unwrap();
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println!("Server thread #{} started", thread_id);
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loop {
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match NtpPacket::receive(&socket) {
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Ok(request) => {
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if debug {
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println!("Thread #{} received {:?}", thread_id, request);
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}
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if request.local_ts.diff_to_sec(&last_update).abs() > 0.1 {
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cached_state = *state.lock().unwrap();
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last_update = request.local_ts;
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if debug {
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println!("Thread #{} updated its state", thread_id);
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}
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}
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match request.make_response(&cached_state) {
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Some(response) => {
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match response.send(&socket) {
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Ok(_) => {
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if debug {
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println!("Thread #{} sent {:?}", thread_id, response);
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}
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},
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Err(e) => println!("Thread #{} failed to send packet to {}: {}",
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thread_id, response.remote_addr, e)
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}
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},
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None => {}
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}
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},
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Err(e) => {
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println!("Thread #{} failed to receive packet: {}", thread_id, e);
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},
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}
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}
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}
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fn update_state(state: Arc<Mutex<NtpServerState>>, addr: SocketAddr, debug: bool) {
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let udp_builder = UdpBuilder::new_v4().unwrap();
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let socket = udp_builder.bind("0.0.0.0:0").unwrap();
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let request = NtpPacket::new_request(addr);
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let mut new_state: Option<NtpServerState> = None;
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socket.set_read_timeout(Some(Duration::new(1, 0))).unwrap();
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match request.send(&socket) {
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Ok(_) => {
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if debug {
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println!("Client sent {:?}", request);
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}
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},
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Err(e) => panic!("Client failed to send packet: {}", e)
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}
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loop {
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let response = match NtpPacket::receive(&socket) {
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Ok(packet) => {
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if debug {
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println!("Client received {:?}", packet);
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}
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if !packet.is_valid_response(&request) {
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println!("Client received unexpected {:?}", packet);
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continue;
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}
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packet
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},
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Err(e) => {
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if debug {
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println!("Client failed to receive packet: {}", e);
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}
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break;
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}
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};
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new_state = Some(response.get_server_state());
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break;
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}
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if let Ok(mut state) = state.lock() {
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if let Some(new_state) = new_state {
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*state = new_state;
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}
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state.dispersion.increment();
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}
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}
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fn run(&self) {
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let mut threads = vec![];
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let mut id = 0;
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let quit = false;
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for socket in &self.sockets {
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id = id + 1;
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let state = self.state.clone();
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let debug = self.debug;
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let cloned_socket = socket.try_clone().unwrap();
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threads.push(thread::spawn(move || {NtpServer::process_requests(id, debug, cloned_socket, state); }));
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}
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while ! quit {
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NtpServer::update_state(self.state.clone(), self.server_addr.parse().unwrap(), self.debug);
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thread::sleep(Duration::new(1, 0));
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}
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for thread in threads {
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let _ = thread.join();
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}
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}
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}
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fn print_usage(opts: Options) {
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let brief = format!("Usage: rsntp [OPTIONS]");
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print!("{}", opts.usage(&brief));
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}
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fn main() {
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let args: Vec<String> = env::args().collect();
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let mut addrs = Vec::new();
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let mut opts = Options::new();
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opts.optopt("4", "ipv4-threads", "set number of IPv4 server threads (1)", "NUM");
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opts.optopt("6", "ipv6-threads", "set number of IPv6 server threads (1)", "NUM");
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opts.optopt("a", "ipv4-address", "set local address of IPv4 server sockets (0.0.0.0:123)", "ADDR:PORT");
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opts.optopt("b", "ipv6-address", "set local address of IPv6 server sockets ([::]:123)", "ADDR:PORT");
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opts.optopt("s", "server-address", "set server address (127.0.0.1:11123)", "ADDR:PORT");
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opts.optopt("u", "user", "run as USER", "USER");
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opts.optopt("r", "root", "change root directory", "DIR");
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opts.optflag("d", "debug", "Enable debug messages");
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opts.optflag("h", "help", "Print this help message");
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let matches = match opts.parse(&args[1..]) {
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Ok(m) => m,
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Err(e) => {
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println!("{}", e);
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print_usage(opts);
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return;
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}
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};
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if matches.opt_present("h") {
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print_usage(opts);
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return;
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}
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let server_addr = matches.opt_str("s").unwrap_or("127.0.0.1:11123".to_string());
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let n4 = matches.opt_str("4").unwrap_or("1".to_string()).parse().unwrap_or(1);
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let n6 = matches.opt_str("6").unwrap_or("1".to_string()).parse().unwrap_or(1);
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let local_address4 = matches.opt_str("a").unwrap_or("0.0.0.0:123".to_string());
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let local_address6 = matches.opt_str("b").unwrap_or("[::]:123".to_string());
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for _ in 0..n4 {
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addrs.push(local_address4.clone());
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}
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for _ in 0..n6 {
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addrs.push(local_address6.clone());
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}
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let server = NtpServer::new(addrs, server_addr, matches.opt_present("d"));
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if matches.opts_present(&["r".to_string(), "u".to_string()]) {
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privdrop::PrivDrop::default()
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.chroot(matches.opt_str("r").unwrap_or("/".to_string()))
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.user(&matches.opt_str("u").unwrap_or("root".to_string()))
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.unwrap_or_else(|e| { panic!("Couldn't set user: {}", e) })
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.apply()
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.unwrap_or_else(|e| { panic!("Couldn't drop privileges: {}", e) });
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}
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server.run();
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}
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