368 lines
12 KiB
Rust
368 lines
12 KiB
Rust
// GStreamer
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//
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// Copyright (C) 2015-2023 Sebastian Dröge <sebastian@centricular.com>
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//
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// This Source Code Form is subject to the terms of the Mozilla Public License, v2.0.
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// If a copy of the MPL was not distributed with this file, You can obtain one at
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// <https://mozilla.org/MPL/2.0/>.
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//
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// SPDX-License-Identifier: MPL-2.0
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//! Helper process that runs setuid root or with appropriate privileges to
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//! listen on ports < 1024, do multicast operations and get MAC addresses of
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//! interfaces. Privileges are dropped after these operations are done.
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//!
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//! It listens on the PTP multicast group on port 319 and 320 and forwards
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//! everything received there to stdout, while forwarding everything received
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//! on stdin to those sockets.
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//! Additionally it provides the MAC address of a network interface via stdout
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use std::{
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io::{Read, Write},
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net::{Ipv4Addr, SocketAddr, UdpSocket},
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};
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#[macro_use]
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mod log;
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mod args;
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mod clock;
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mod error;
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mod ffi;
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mod io;
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mod net;
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mod privileges;
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mod rand;
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mod thread;
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use error::{Context, Error};
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use rand::rand;
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/// PTP Multicast group.
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const PTP_MULTICAST_ADDR: Ipv4Addr = Ipv4Addr::new(224, 0, 1, 129);
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/// PTP Event message port.
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const PTP_EVENT_PORT: u16 = 319;
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/// PTP General message port.
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const PTP_GENERAL_PORT: u16 = 320;
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/// StdIO Message Types.
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/// PTP message for the event socket.
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const MSG_TYPE_EVENT: u8 = 0;
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/// PTP message for the general socket.
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const MSG_TYPE_GENERAL: u8 = 1;
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/// Clock ID message
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const MSG_TYPE_CLOCK_ID: u8 = 2;
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/// Send time ACK message
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const MSG_TYPE_SEND_TIME_ACK: u8 = 3;
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/// Reads a big endian 64 bit integer from a slice.
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fn read_u64_be(s: &[u8]) -> u64 {
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assert!(s.len() >= 8);
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(s[7] as u64)
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| ((s[6] as u64) << 8)
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| ((s[5] as u64) << 16)
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| ((s[4] as u64) << 24)
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| ((s[3] as u64) << 32)
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| ((s[2] as u64) << 40)
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| ((s[1] as u64) << 48)
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| ((s[0] as u64) << 56)
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}
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/// Reads a big endian 16 bit integer from a slice.
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fn read_u16_be(s: &[u8]) -> u16 {
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assert!(s.len() >= 2);
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(s[1] as u16) | ((s[0] as u16) << 8)
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}
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/// Create a new `UdpSocket` for the given port and configure it for PTP.
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fn create_socket(port: u16) -> Result<UdpSocket, Error> {
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let socket = UdpSocket::bind(SocketAddr::from((Ipv4Addr::UNSPECIFIED, port)))
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.with_context(|| format!("Failed to bind socket to port {}", port))?;
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socket
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.set_nonblocking(true)
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.context("Failed setting socket non-blocking")?;
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socket.set_ttl(1).context("Failed setting TTL on socket")?;
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socket
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.set_multicast_ttl_v4(1)
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.context("Failed to set multicast TTL on socket")?;
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net::set_reuse(&socket);
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Ok(socket)
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}
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/// Join the multicast groups for PTP on the configured interfaces.
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fn join_multicast(
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args: &args::Args,
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event_socket: &UdpSocket,
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general_socket: &UdpSocket,
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) -> Result<[u8; 8], Error> {
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let mut ifaces = net::query_interfaces().context("Failed to query network interfaces")?;
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if ifaces.is_empty() {
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bail!("No suitable network interfaces for PTP found");
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}
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if !args.interfaces.is_empty() {
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ifaces.retain(|iface| {
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for filter_iface in &args.interfaces {
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if &iface.name == filter_iface {
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return true;
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}
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if let Some(ref other_name) = iface.other_name {
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if other_name == filter_iface {
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return true;
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}
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}
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if let Ok(addr) = filter_iface.parse::<Ipv4Addr>() {
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if addr == iface.ip_addr {
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return true;
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}
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}
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}
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info!("Interface {} filtered out", iface.name);
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false
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});
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if ifaces.is_empty() {
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bail!("None of the selected network interfaces found");
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}
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if ifaces.len() != args.interfaces.len() {
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bail!("Not all selected network interfaces found");
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}
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}
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for iface in &ifaces {
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info!("Binding to interface {}", iface.name);
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}
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for socket in [&event_socket, &general_socket].iter() {
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for iface in &ifaces {
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net::join_multicast_v4(socket, &PTP_MULTICAST_ADDR, iface)
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.context("Failed to join multicast group")?;
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}
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}
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let clock_id = if args.clock_id == 0 {
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ifaces
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.iter()
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.find_map(|iface| iface.hw_addr)
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.map(|hw_addr| {
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[
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hw_addr[0], hw_addr[1], hw_addr[2], 0xff, 0xfe, hw_addr[3], hw_addr[4],
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hw_addr[5],
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]
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})
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.unwrap_or_else(rand)
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} else {
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args.clock_id.to_be_bytes()
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};
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info!("Using clock ID {:?}", clock_id);
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Ok(clock_id)
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}
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fn run() -> Result<(), Error> {
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let args = args::parse_args().context("Failed parsing commandline parameters")?;
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let event_socket = create_socket(PTP_EVENT_PORT).context("Failed creating event socket")?;
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let general_socket =
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create_socket(PTP_GENERAL_PORT).context("Failed creating general socket")?;
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thread::set_priority().context("Failed to set thread priority")?;
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privileges::drop().context("Failed dropping privileges")?;
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let clock_id = join_multicast(&args, &event_socket, &general_socket)
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.context("Failed joining multicast groups")?;
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let mut poll = io::Poll::new(event_socket, general_socket).context("Failed creating poller")?;
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// Write clock ID first
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{
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let mut clock_id_data = [0u8; 3 + 8];
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clock_id_data[0..2].copy_from_slice(&8u16.to_be_bytes());
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clock_id_data[2] = MSG_TYPE_CLOCK_ID;
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clock_id_data[3..].copy_from_slice(&clock_id);
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poll.stdout()
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.write_all(&clock_id_data)
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.context("Failed writing to stdout")?;
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}
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// Now read-write from stdin/stdout and the sockets
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//
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// We assume that stdout never blocks and stdin receives a complete valid packet whenever it is
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// ready and never blocks in the middle of a packet.
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let mut socket_buffer = [0u8; 8192];
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let mut stdinout_buffer = [0u8; 8192 + 3 + 8];
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loop {
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let poll_res = poll.poll().context("Failed polling")?;
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// If any of the sockets are ready, continue reading packets from them until no more
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// packets are left and directly forward them to stdout.
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'next_socket: for idx in [poll_res.event_socket, poll_res.general_socket]
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.iter()
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.enumerate()
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.filter_map(|(idx, r)| if *r { Some(idx) } else { None })
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{
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let idx = idx as u8;
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let res = match idx {
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MSG_TYPE_EVENT => poll.event_socket().recv_from(&mut socket_buffer),
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MSG_TYPE_GENERAL => poll.general_socket().recv_from(&mut socket_buffer),
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_ => unreachable!(),
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};
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match res {
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Err(err) if err.kind() == std::io::ErrorKind::WouldBlock => {
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continue 'next_socket;
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}
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Err(err) => {
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bail!(
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source: err,
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"Failed reading from {} socket",
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if idx == MSG_TYPE_EVENT {
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"event"
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} else {
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"general"
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}
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);
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}
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Ok((read, addr)) => {
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let recv_time = clock::time();
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if args.verbose {
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trace!(
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"Received {} bytes from {} socket from {} at {}",
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read,
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if idx == MSG_TYPE_EVENT {
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"event"
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} else {
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"general"
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},
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addr,
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recv_time,
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);
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}
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stdinout_buffer[0..2].copy_from_slice(&(read as u16 + 8).to_be_bytes());
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stdinout_buffer[2] = idx;
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stdinout_buffer[3..][..8].copy_from_slice(&recv_time.to_be_bytes());
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stdinout_buffer[11..][..read].copy_from_slice(&socket_buffer[..read]);
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poll.stdout()
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.write_all(&stdinout_buffer[..(read + 3 + 8)])
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.context("Failed writing to stdout")?;
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}
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}
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}
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// After handling the sockets check if a packet is available on stdin, read it and forward
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// it to the corresponding socket.
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if poll_res.stdin {
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poll.stdin()
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.read_exact(&mut stdinout_buffer[0..3])
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.context("Failed reading packet header from stdin")?;
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let size = u16::from_be_bytes([stdinout_buffer[0], stdinout_buffer[1]]);
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if size as usize > stdinout_buffer.len() {
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bail!("Invalid packet size on stdin {}", size);
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}
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let type_ = stdinout_buffer[2];
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poll.stdin()
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.read_exact(&mut stdinout_buffer[0..size as usize])
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.context("Failed reading packet body from stdin")?;
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if type_ != MSG_TYPE_EVENT && type_ != MSG_TYPE_GENERAL {
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warn!("Unexpected stdin message type {}", type_);
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continue;
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}
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if args.verbose {
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trace!(
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"Received {} bytes for {} socket from stdin",
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size,
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if type_ == MSG_TYPE_EVENT {
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"event"
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} else {
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"general"
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},
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);
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}
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if size < 8 + 32 {
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bail!("Invalid packet body size");
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}
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let main_send_time = read_u64_be(&stdinout_buffer[..8]);
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let buf = &stdinout_buffer[8..size as usize];
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let message_type = buf[0] & 0x0f;
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let domain_number = buf[4];
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let seqnum = read_u16_be(&buf[30..][..2]);
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let send_time = clock::time();
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match type_ {
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MSG_TYPE_EVENT => poll
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.event_socket()
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.send_to(buf, (PTP_MULTICAST_ADDR, PTP_EVENT_PORT)),
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MSG_TYPE_GENERAL => poll
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.general_socket()
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.send_to(buf, (PTP_MULTICAST_ADDR, PTP_GENERAL_PORT)),
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_ => unreachable!(),
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}
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.with_context(|| {
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format!(
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"Failed sending to {} socket",
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if type_ == MSG_TYPE_EVENT {
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"event"
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} else {
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"general"
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}
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)
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})?;
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if args.verbose {
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trace!(
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"Sending SEND_TIME_ACK for message type {}, domain number {}, seqnum {} received at {} at {}",
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message_type,
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domain_number,
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seqnum,
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main_send_time,
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send_time,
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);
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}
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stdinout_buffer[0..2].copy_from_slice(&12u16.to_be_bytes());
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stdinout_buffer[2] = MSG_TYPE_SEND_TIME_ACK;
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let send_time_ack_msg = &mut stdinout_buffer[3..];
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send_time_ack_msg[..8].copy_from_slice(&send_time.to_be_bytes());
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send_time_ack_msg[8] = message_type;
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send_time_ack_msg[9] = domain_number;
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send_time_ack_msg[10..][..2].copy_from_slice(&seqnum.to_be_bytes());
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poll.stdout()
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.write_all(&stdinout_buffer[..(3 + 12)])
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.context("Failed writing to stdout")?;
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}
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}
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}
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/// Custom panic hook so we can print them to stderr in a format the main process understands
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fn panic_hook(info: &std::panic::PanicInfo) {
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error!("Panicked. {}", info);
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}
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fn main() {
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std::panic::set_hook(Box::new(panic_hook));
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if let Err(err) = run() {
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error!("Exited with error: {:?}", err);
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}
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}
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