134 lines
4.6 KiB
Rust
134 lines
4.6 KiB
Rust
//! ICE-like NAT traversal logic.
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//!
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//! Doesn't follow the specific ICE protocol, but takes great inspiration from RFC 8445
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//! and applies it to a protocol more specific to innernet.
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use std::time::{Duration, Instant};
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use anyhow::Error;
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use shared::{
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wg::{DeviceExt, PeerInfoExt},
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Endpoint, Peer, PeerDiff,
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};
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use wireguard_control::{Backend, Device, DeviceUpdate, InterfaceName, Key, PeerConfigBuilder};
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pub const STEP_INTERVAL: Duration = Duration::from_secs(5);
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pub struct NatTraverse<'a> {
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interface: &'a InterfaceName,
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backend: Backend,
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remaining: Vec<Peer>,
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}
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impl<'a> NatTraverse<'a> {
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pub fn new(
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interface: &'a InterfaceName,
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backend: Backend,
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diffs: &[PeerDiff],
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) -> Result<Self, Error> {
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// Filter out removed peers from diffs list.
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let mut remaining: Vec<_> = diffs.iter().filter_map(|diff| diff.new).cloned().collect();
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for peer in &mut remaining {
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// Limit reported alternative candidates to 10.
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peer.candidates.truncate(10);
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// remove server-reported endpoint from elsewhere in the list if it existed.
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let endpoint = peer.endpoint.clone();
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peer.candidates
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.retain(|addr| Some(addr) != endpoint.as_ref());
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}
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let mut nat_traverse = Self {
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interface,
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backend,
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remaining,
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};
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nat_traverse.refresh_remaining()?;
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Ok(nat_traverse)
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}
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pub fn is_finished(&self) -> bool {
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self.remaining.is_empty()
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}
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pub fn remaining(&self) -> usize {
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self.remaining.len()
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}
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/// Refreshes the current state of candidate traversal attempts, returning
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/// the peers that have been exhausted of all options (not included are
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/// peers that have successfully connected, or peers removed from the interface).
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fn refresh_remaining(&mut self) -> Result<Vec<Peer>, Error> {
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let device = Device::get(self.interface, self.backend)?;
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// Remove connected and missing peers
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self.remaining.retain(|peer| {
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if let Some(peer_info) = device.get_peer(&peer.public_key) {
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let recently_connected = peer_info.is_recently_connected();
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if recently_connected {
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log::debug!(
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"peer {} removed from NAT traverser (connected!).",
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peer.name
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);
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}
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!recently_connected
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} else {
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log::debug!(
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"peer {} removed from NAT traverser (no longer on interface).",
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peer.name
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);
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false
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}
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});
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let (exhausted, remaining): (Vec<_>, Vec<_>) = self
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.remaining
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.drain(..)
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.partition(|peer| peer.candidates.is_empty());
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self.remaining = remaining;
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Ok(exhausted)
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}
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pub fn step(&mut self) -> Result<(), Error> {
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let exhausted = self.refresh_remaining()?;
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// Reset peer endpoints that had no viable candidates back to the server-reported one, if it exists.
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let reset_updates = exhausted
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.into_iter()
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.filter_map(|peer| set_endpoint(&peer.public_key, peer.endpoint.as_ref()));
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// Set all peers' endpoints to their next available candidate.
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let candidate_updates = self.remaining.iter_mut().filter_map(|peer| {
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let endpoint = peer.candidates.pop();
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if let Some(endpoint) = &endpoint {
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log::debug!("trying endpoint {} for peer {}", endpoint, peer.name);
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}
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set_endpoint(&peer.public_key, endpoint.as_ref())
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});
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let updates: Vec<_> = reset_updates.chain(candidate_updates).collect();
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DeviceUpdate::new()
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.add_peers(&updates)
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.apply(self.interface, self.backend)?;
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let start = Instant::now();
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while start.elapsed() < STEP_INTERVAL {
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self.refresh_remaining()?;
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if self.is_finished() {
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log::debug!("NAT traverser is finished!");
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break;
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}
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std::thread::sleep(Duration::from_millis(100));
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}
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Ok(())
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}
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}
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/// Return a PeerConfigBuilder if an endpoint exists and resolves successfully.
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fn set_endpoint(public_key: &str, endpoint: Option<&Endpoint>) -> Option<PeerConfigBuilder> {
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endpoint
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.and_then(|endpoint| endpoint.resolve().ok())
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.map(|addr| {
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PeerConfigBuilder::new(&Key::from_base64(public_key).unwrap()).set_endpoint(addr)
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})
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}
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