87 lines
2.7 KiB
Rust
87 lines
2.7 KiB
Rust
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//! Relay candidacy evaluation.
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//!
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//! Determines whether this node is eligible to run an embedded relay server
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//! by checking a set of extensible rules (public IP, port availability, etc.).
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use std::net::{IpAddr, SocketAddr, UdpSocket};
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// ─── Candidacy ──────────────────────────────────────────────────────────
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/// Result of evaluating a single candidacy rule.
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pub enum CandidacyResult {
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Eligible,
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Ineligible(String),
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}
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/// Extensible rule for relay candidacy evaluation.
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pub trait CandidacyRule: Send {
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fn evaluate(&self) -> CandidacyResult;
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}
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/// Checks whether the node's outbound IP is public (non-RFC1918, non-loopback).
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pub struct PublicIpRule;
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impl PublicIpRule {
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pub fn outbound_ip() -> Option<IpAddr> {
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let sock = UdpSocket::bind("0.0.0.0:0").ok()?;
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sock.connect("192.0.2.1:80").ok()?; // RFC 5737 TEST-NET-1 (non-routable)
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Some(sock.local_addr().ok()?.ip())
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}
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fn is_public(ip: &IpAddr) -> bool {
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match ip {
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IpAddr::V4(v4) => {
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!v4.is_loopback()
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&& !v4.is_private()
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&& !v4.is_link_local()
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&& !v4.is_unspecified()
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}
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IpAddr::V6(v6) => !v6.is_loopback() && !v6.is_unspecified(),
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}
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}
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}
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impl CandidacyRule for PublicIpRule {
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fn evaluate(&self) -> CandidacyResult {
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match Self::outbound_ip() {
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Some(ip) if Self::is_public(&ip) => CandidacyResult::Eligible,
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Some(ip) => CandidacyResult::Ineligible(format!("outbound IP {ip} is private")),
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None => CandidacyResult::Ineligible("could not determine outbound IP".into()),
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}
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}
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}
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/// Checks whether the desired relay port is available for binding.
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pub struct PortBindRule {
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addr: SocketAddr,
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}
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impl PortBindRule {
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pub fn new(addr: SocketAddr) -> Self {
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Self { addr }
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}
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}
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impl CandidacyRule for PortBindRule {
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fn evaluate(&self) -> CandidacyResult {
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match std::net::TcpListener::bind(self.addr) {
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Ok(_) => CandidacyResult::Eligible,
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Err(e) => CandidacyResult::Ineligible(format!(
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"cannot bind {}: {e}",
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self.addr
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)),
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}
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}
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}
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/// Evaluate all candidacy rules. Returns `Ok(())` if all pass, or
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/// `Err(reason)` with the first failure reason.
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pub fn evaluate_candidacy(rules: &[Box<dyn CandidacyRule>]) -> Result<(), String> {
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for rule in rules {
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if let CandidacyResult::Ineligible(reason) = rule.evaluate() {
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return Err(reason);
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}
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}
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Ok(())
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}
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