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|
//! Addresses without a route from here, left out as if `--libp2p-ignore` named them: a
//! node without IPv6 to the internet doesn't keep, show or dial peers' public IPv6
//! addresses; one without a route to another LAN, that LAN's. And with
//! `--libp2p-internet-hosts`, whether there's a route to the internet at all, per
//! family: a node without one doesn't publish its own public addresses of that family.
//!
//! Whether there is a route is asked of the operating system: a UDP socket "connected"
//! to the address (no packet is sent) fails where the routing table has none. Asked
//! per range (`ROUTE_PREFIX_V4`, `ROUTE_PREFIX_V6`) of the addresses heard of, and
//! asked again every `ROUTES_RECHECK`: a range gets a route (IPv6 comes up), and its
//! addresses are taken again as they're heard of next (the member list, identify);
//! one loses its route, and the addresses there are dropped.
use std::net::{IpAddr, Ipv4Addr, Ipv6Addr, SocketAddr, UdpSocket};
use super::*;
/// The ranges routes are asked for: an IPv4 /24 or an IPv6 /64, as far as a route
/// usually differs within them.
const ROUTE_PREFIX_V4: u8 = 24;
const ROUTE_PREFIX_V6: u8 = 64;
/// How long an answer is taken for one.
const ROUTES_RECHECK: Duration = Duration::from_secs(30);
/// Ranges remembered at most.
const MAX_RANGES: usize = 1024;
/// How long resolving `--libp2p-internet-hosts` may take, each time.
const RESOLVE_WITHIN: Duration = Duration::from_secs(5);
/// Whether the routing table has a route to `ip`.
pub(super) fn has_route(ip: IpAddr) -> bool {
let any: SocketAddr = match ip {
IpAddr::V4(_) => (Ipv4Addr::UNSPECIFIED, 0).into(),
IpAddr::V6(_) => (Ipv6Addr::UNSPECIFIED, 0).into(),
};
UdpSocket::bind(any)
.and_then(|socket| socket.connect((ip, 9)))
.is_ok()
}
/// The answers, by range, and the question asked (`has_route`, or a stand-in in tests).
pub(super) struct Routes {
known: HashMap<IpRange, (bool, tokio::time::Instant)>,
/// Whether there is a route to the internet, per family (IPv4, IPv6), as last
/// asked (`internet`): own public addresses are published only then. True where
/// nobody asks (no `--libp2p-internet-hosts` of that family); false until the first
/// answer where someone does (resolving takes up to `RESOLVE_WITHIN`), so the first
/// member list entry doesn't list addresses nobody can reach.
internet: [bool; 2],
/// `--libp2p-internet-hosts`: names or addresses on the internet, whose routes
/// tell whether there is one to the internet at all.
pub(super) internet_hosts: Vec<String>,
probe: fn(IpAddr) -> bool,
}
impl Default for Routes {
fn default() -> Self {
// Tests don't depend on the host's routes; those that care set `probe`.
#[cfg(test)]
let probe: fn(IpAddr) -> bool = |_| true;
#[cfg(not(test))]
let probe: fn(IpAddr) -> bool = has_route;
Self::with_probe(probe)
}
}
/// The range of `ip` routes are asked for.
fn range_of(ip: IpAddr) -> IpRange {
let prefix = if ip.is_ipv4() {
ROUTE_PREFIX_V4
} else {
ROUTE_PREFIX_V6
};
IpRange::masked(ip, prefix)
}
impl Routes {
/// With `--libp2p-internet-hosts` `internet_hosts`.
pub(super) fn asking(internet_hosts: Vec<String>) -> Self {
let unknown = !internet_hosts.is_empty();
Self {
internet: [!unknown, !unknown],
internet_hosts,
..Self::default()
}
}
pub(super) fn with_probe(probe: fn(IpAddr) -> bool) -> Self {
Self {
known: HashMap::new(),
internet: [true, true],
internet_hosts: Vec::new(),
probe,
}
}
/// Whether `ip` has a route from here: asked if not known lately, told when the
/// answer is news (debug).
pub(super) fn routable(&mut self, ip: IpAddr) -> bool {
let range = range_of(ip);
let now = tokio::time::Instant::now();
if let Some((routable, at)) = self.known.get(&range)
&& now.saturating_duration_since(*at) < ROUTES_RECHECK
{
return *routable;
}
let routable = (self.probe)(ip);
let before = self.known.get(&range).map(|(routable, _)| *routable);
if before.is_none() && self.known.len() >= MAX_RANGES {
self.known.clear();
}
self.known.insert(range, (routable, now));
announce(range, before, routable);
routable
}
/// Asks again for the ranges known; returns those that lost their route, whose
/// addresses are to go.
pub(super) fn recheck(&mut self) -> Vec<IpRange> {
let now = tokio::time::Instant::now();
let mut lost = Vec::new();
for (range, (routable, at)) in &mut self.known {
let now_routable = (self.probe)(range.network);
if *routable != now_routable {
announce(*range, Some(*routable), now_routable);
if !now_routable {
lost.push(*range);
}
}
*routable = now_routable;
*at = now;
}
lost
}
/// Whether there's a route to the internet, per family, by the addresses
/// `--libp2p-internet-hosts` resolved to (`resolve_internet_hosts`): one of them
/// with a route is enough. A family none of them has isn't judged (taken as having
/// one).
pub(super) fn internet(&mut self, hosts: &[IpAddr]) {
for (family, name) in ["IPv4", "IPv6"].into_iter().enumerate() {
let of_family: Vec<IpAddr> = hosts
.iter()
.copied()
.filter(|ip| usize::from(ip.is_ipv6()) == family)
.collect();
let routable = of_family.is_empty() || of_family.iter().any(|ip| (self.probe)(*ip));
if routable != self.internet[family] {
if routable {
debug!(
family = name,
"A route to the internet again: own public addresses published again"
);
} else {
debug!(
family = name,
"No route to the internet: own public addresses not published"
);
}
}
self.internet[family] = routable;
}
}
/// Whether an own address `ip` is worth publishing: not a public one of a family
/// with no route to the internet.
pub(super) fn publishable(&self, ip: IpAddr) -> bool {
!is_public(ip) || self.internet[usize::from(ip.is_ipv6())]
}
}
fn announce(range: IpRange, before: Option<bool>, routable: bool) {
match (before, routable) {
(None | Some(true), false) => {
debug!(range = %range, "No route to an address range: its addresses left out until there is");
}
(Some(false), true) => {
debug!(range = %range, "A route to an address range again: its addresses taken again");
}
_ => {}
}
}
/// The addresses `hosts` (names or addresses) resolve to, within `RESOLVE_WITHIN`; a
/// name that doesn't resolve is left out (told at debug level).
pub(super) async fn resolve_internet_hosts(hosts: &[String]) -> Vec<IpAddr> {
let mut addresses = Vec::new();
for host in hosts {
if let Ok(ip) = host.parse::<IpAddr>() {
addresses.push(ip);
continue;
}
match tokio::time::timeout(RESOLVE_WITHIN, tokio::net::lookup_host((host.as_str(), 0)))
.await
{
Ok(Ok(found)) => addresses.extend(found.map(|address| address.ip())),
Ok(Err(error)) => {
debug!(host = %host, error = %error, "An internet host didn't resolve")
}
Err(_) => debug!(host = %host, "An internet host didn't resolve in time"),
}
}
addresses
}
|
