From c9f1d98f45532df362f71ad70df530ebd9e7f25d Mon Sep 17 00:00:00 2001 From: Razvan Dimescu Date: Sat, 21 Mar 2026 16:45:46 +0200 Subject: [PATCH] add LAN service discovery via UDP multicast MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Numa instances on the same network auto-discover each other's .numa services. No config, no cloud — just multicast on 239.255.70.78:5390. - PeerStore with lazy expiry (90s timeout, 30s broadcast interval) - DNS resolves remote .numa services to peer's LAN IP (not localhost) - Proxy forwards to peer IP for remote services - Graceful degradation if multicast bind fails Co-Authored-By: Claude Opus 4.6 --- Cargo.lock | 19 ++++- Cargo.toml | 1 + src/config.rs | 44 +++++++++++ src/ctx.rs | 29 +++++++- src/lan.rs | 198 ++++++++++++++++++++++++++++++++++++++++++++++++++ src/lib.rs | 1 + src/main.rs | 14 ++++ src/proxy.rs | 15 ++-- 8 files changed, 310 insertions(+), 11 deletions(-) create mode 100644 src/lan.rs diff --git a/Cargo.lock b/Cargo.lock index be1edf2..57a030e 100644 --- a/Cargo.lock +++ b/Cargo.lock @@ -621,7 +621,7 @@ dependencies = [ "libc", "percent-encoding", "pin-project-lite", - "socket2", + "socket2 0.6.3", "tokio", "tower-service", "tracing", @@ -946,6 +946,7 @@ dependencies = [ "rustls", "serde", "serde_json", + "socket2 0.5.10", "time", "tokio", "tokio-rustls", @@ -1062,7 +1063,7 @@ dependencies = [ "quinn-udp", "rustc-hash", "rustls", - "socket2", + "socket2 0.6.3", "thiserror 2.0.18", "tokio", "tracing", @@ -1099,7 +1100,7 @@ dependencies = [ "cfg_aliases", "libc", "once_cell", - "socket2", + "socket2 0.6.3", "tracing", "windows-sys 0.60.2", ] @@ -1407,6 +1408,16 @@ version = "1.15.1" source = "registry+https://github.com/rust-lang/crates.io-index" checksum = "67b1b7a3b5fe4f1376887184045fcf45c69e92af734b7aaddc05fb777b6fbd03" +[[package]] +name = "socket2" +version = "0.5.10" +source = "registry+https://github.com/rust-lang/crates.io-index" +checksum = "e22376abed350d73dd1cd119b57ffccad95b4e585a7cda43e286245ce23c0678" +dependencies = [ + "libc", + "windows-sys 0.52.0", +] + [[package]] name = "socket2" version = "0.6.3" @@ -1566,7 +1577,7 @@ dependencies = [ "libc", "mio", "pin-project-lite", - "socket2", + "socket2 0.6.3", "tokio-macros", "windows-sys 0.61.2", ] diff --git a/Cargo.toml b/Cargo.toml index 990a6b6..31d6481 100644 --- a/Cargo.toml +++ b/Cargo.toml @@ -22,6 +22,7 @@ hyper = { version = "1", features = ["client", "http1", "server"] } hyper-util = { version = "0.1", features = ["client-legacy", "http1", "tokio"] } http-body-util = "0.1" futures = "0.3" +socket2 = "0.5" rcgen = { version = "0.13", features = ["pem", "x509-parser"] } time = "0.3" rustls = "0.23" diff --git a/src/config.rs b/src/config.rs index 8359983..d7a9a19 100644 --- a/src/config.rs +++ b/src/config.rs @@ -25,6 +25,8 @@ pub struct Config { pub proxy: ProxyConfig, #[serde(default)] pub services: Vec, + #[serde(default)] + pub lan: LanConfig, } #[derive(Deserialize)] @@ -202,6 +204,48 @@ pub struct ServiceConfig { pub target_port: u16, } +#[derive(Deserialize, Clone)] +pub struct LanConfig { + #[serde(default = "default_lan_enabled")] + pub enabled: bool, + #[serde(default = "default_lan_multicast_group")] + pub multicast_group: String, + #[serde(default = "default_lan_port")] + pub port: u16, + #[serde(default = "default_lan_broadcast_interval")] + pub broadcast_interval_secs: u64, + #[serde(default = "default_lan_peer_timeout")] + pub peer_timeout_secs: u64, +} + +impl Default for LanConfig { + fn default() -> Self { + LanConfig { + enabled: default_lan_enabled(), + multicast_group: default_lan_multicast_group(), + port: default_lan_port(), + broadcast_interval_secs: default_lan_broadcast_interval(), + peer_timeout_secs: default_lan_peer_timeout(), + } + } +} + +fn default_lan_enabled() -> bool { + true +} +fn default_lan_multicast_group() -> String { + "239.255.70.78".to_string() +} +fn default_lan_port() -> u16 { + 5390 +} +fn default_lan_broadcast_interval() -> u64 { + 30 +} +fn default_lan_peer_timeout() -> u64 { + 90 +} + pub fn load_config(path: &str) -> Result { if !Path::new(path).exists() { return Ok(Config::default()); diff --git a/src/ctx.rs b/src/ctx.rs index cf485bd..d555fad 100644 --- a/src/ctx.rs +++ b/src/ctx.rs @@ -16,6 +16,7 @@ use crate::packet::DnsPacket; use crate::query_log::{QueryLog, QueryLogEntry}; use crate::question::QueryType; use crate::record::DnsRecord; +use crate::lan::PeerStore; use crate::service_store::ServiceStore; use crate::stats::{QueryPath, ServerStats}; use crate::system_dns::ForwardingRule; @@ -29,6 +30,7 @@ pub struct ServerCtx { pub blocklist: Mutex, pub query_log: Mutex, pub services: Mutex, + pub lan_peers: Mutex, pub forwarding_rules: Vec, pub upstream: SocketAddr, pub timeout: Duration, @@ -67,16 +69,39 @@ pub async fn handle_query( } else if !ctx.proxy_tld_suffix.is_empty() && (qname.ends_with(&ctx.proxy_tld_suffix) || qname == ctx.proxy_tld) { + // Resolve .numa: local services → 127.0.0.1, LAN peers → peer IP + let service_name = qname + .strip_suffix(&ctx.proxy_tld_suffix) + .unwrap_or(&qname); + let resolve_ip = { + let local = ctx.services.lock().unwrap(); + if local.lookup(service_name).is_some() { + std::net::Ipv4Addr::LOCALHOST + } else { + let mut peers = ctx.lan_peers.lock().unwrap(); + peers + .lookup(service_name) + .and_then(|(ip, _)| match ip { + std::net::IpAddr::V4(v4) => Some(v4), + _ => None, + }) + .unwrap_or(std::net::Ipv4Addr::LOCALHOST) + } + }; let mut resp = DnsPacket::response_from(&query, ResultCode::NOERROR); match qtype { QueryType::AAAA => resp.answers.push(DnsRecord::AAAA { domain: qname.clone(), - addr: std::net::Ipv6Addr::LOCALHOST, + addr: if resolve_ip == std::net::Ipv4Addr::LOCALHOST { + std::net::Ipv6Addr::LOCALHOST + } else { + resolve_ip.to_ipv6_mapped() + }, ttl: 300, }), _ => resp.answers.push(DnsRecord::A { domain: qname.clone(), - addr: std::net::Ipv4Addr::LOCALHOST, + addr: resolve_ip, ttl: 300, }), } diff --git a/src/lan.rs b/src/lan.rs new file mode 100644 index 0000000..f693f71 --- /dev/null +++ b/src/lan.rs @@ -0,0 +1,198 @@ +use std::collections::HashMap; +use std::net::{IpAddr, Ipv4Addr, SocketAddr}; +use std::sync::Arc; +use std::time::{Duration, Instant}; + +use log::{debug, info, warn}; +use serde::{Deserialize, Serialize}; + +use crate::config::LanConfig; +use crate::ctx::ServerCtx; + +// --- Peer Store --- + +pub struct PeerStore { + peers: HashMap, + timeout: Duration, +} + +impl PeerStore { + pub fn new(timeout_secs: u64) -> Self { + PeerStore { + peers: HashMap::new(), + timeout: Duration::from_secs(timeout_secs), + } + } + + pub fn update(&mut self, host: IpAddr, services: &[(String, u16)]) { + let now = Instant::now(); + for (name, port) in services { + self.peers + .insert(name.to_lowercase(), (host, *port, now)); + } + } + + pub fn lookup(&mut self, name: &str) -> Option<(IpAddr, u16)> { + let key = name.to_lowercase(); + let entry = self.peers.get(&key)?; + if entry.2.elapsed() > self.timeout { + self.peers.remove(&key); + return None; + } + Some((entry.0, entry.1)) + } + + pub fn list(&mut self) -> Vec<(String, IpAddr, u16, u64)> { + let now = Instant::now(); + self.peers.retain(|_, (_, _, seen)| now.duration_since(*seen) < self.timeout); + self.peers + .iter() + .map(|(name, (ip, port, seen))| { + (name.clone(), *ip, *port, now.duration_since(*seen).as_secs()) + }) + .collect() + } +} + +// --- Multicast --- + +#[derive(Serialize, Deserialize)] +struct Announcement { + host: String, + services: Vec, +} + +#[derive(Serialize, Deserialize)] +struct AnnouncedService { + name: String, + port: u16, +} + +pub fn detect_lan_ip() -> Option { + let socket = std::net::UdpSocket::bind("0.0.0.0:0").ok()?; + socket.connect("8.8.8.8:80").ok()?; + match socket.local_addr().ok()? { + SocketAddr::V4(addr) => Some(*addr.ip()), + _ => None, + } +} + +pub async fn start_lan_discovery(ctx: Arc, config: &LanConfig) { + let multicast_group: Ipv4Addr = match config.multicast_group.parse() { + Ok(g) => g, + Err(e) => { + warn!("LAN: invalid multicast group {}: {}", config.multicast_group, e); + return; + } + }; + let port = config.port; + let interval = Duration::from_secs(config.broadcast_interval_secs); + + let local_ip = detect_lan_ip().unwrap_or(Ipv4Addr::LOCALHOST); + info!("LAN discovery on {}:{}, local IP {}", multicast_group, port, local_ip); + + // Create socket with SO_REUSEADDR for multicast + let std_socket = match create_multicast_socket(multicast_group, port) { + Ok(s) => s, + Err(e) => { + warn!("LAN: could not bind multicast socket: {} — LAN discovery disabled", e); + return; + } + }; + let socket = match tokio::net::UdpSocket::from_std(std_socket) { + Ok(s) => s, + Err(e) => { + warn!("LAN: tokio socket conversion failed: {}", e); + return; + } + }; + let socket = Arc::new(socket); + + // Spawn sender + let sender_ctx = Arc::clone(&ctx); + let sender_socket = Arc::clone(&socket); + let local_ip_str = local_ip.to_string(); + let self_filter = local_ip_str.clone(); + let dest = SocketAddr::new(IpAddr::V4(multicast_group), port); + tokio::spawn(async move { + let mut ticker = tokio::time::interval(interval); + loop { + ticker.tick().await; + let services: Vec = { + let store = sender_ctx.services.lock().unwrap(); + store + .list() + .iter() + .map(|e| AnnouncedService { + name: e.name.clone(), + port: e.target_port, + }) + .collect() + }; + if services.is_empty() { + continue; + } + let announcement = Announcement { + host: local_ip_str.clone(), + services, + }; + if let Ok(json) = serde_json::to_vec(&announcement) { + let _ = sender_socket.send_to(&json, dest).await; + } + } + }); + + // Receiver loop + let mut buf = vec![0u8; 4096]; + loop { + let (len, src) = match socket.recv_from(&mut buf).await { + Ok(r) => r, + Err(e) => { + debug!("LAN recv error: {}", e); + continue; + } + }; + let announcement: Announcement = match serde_json::from_slice(&buf[..len]) { + Ok(a) => a, + Err(_) => continue, + }; + // Skip self-announcements + if announcement.host == self_filter { + continue; + } + let peer_ip: IpAddr = match announcement.host.parse() { + Ok(ip) => ip, + Err(_) => continue, + }; + let services: Vec<(String, u16)> = announcement + .services + .iter() + .map(|s| (s.name.clone(), s.port)) + .collect(); + let count = services.len(); + ctx.lan_peers.lock().unwrap().update(peer_ip, &services); + debug!( + "LAN: {} services from {} (via {})", + count, announcement.host, src + ); + } +} + +fn create_multicast_socket( + group: Ipv4Addr, + port: u16, +) -> std::io::Result { + use std::net::SocketAddrV4; + + let addr = SocketAddrV4::new(Ipv4Addr::UNSPECIFIED, port); + let socket = socket2::Socket::new( + socket2::Domain::IPV4, + socket2::Type::DGRAM, + Some(socket2::Protocol::UDP), + )?; + socket.set_reuse_address(true)?; + socket.set_nonblocking(true)?; + socket.bind(&socket2::SockAddr::from(addr))?; + socket.join_multicast_v4(&group, &Ipv4Addr::UNSPECIFIED)?; + Ok(socket.into()) +} diff --git a/src/lib.rs b/src/lib.rs index ad9355e..1d41c04 100644 --- a/src/lib.rs +++ b/src/lib.rs @@ -6,6 +6,7 @@ pub mod config; pub mod ctx; pub mod forward; pub mod header; +pub mod lan; pub mod override_store; pub mod packet; pub mod proxy; diff --git a/src/main.rs b/src/main.rs index 9c1a543..dd6cead 100644 --- a/src/main.rs +++ b/src/main.rs @@ -127,6 +127,7 @@ async fn main() -> numa::Result<()> { blocklist: Mutex::new(blocklist), query_log: Mutex::new(QueryLog::new(1000)), services: Mutex::new(service_store), + lan_peers: Mutex::new(numa::lan::PeerStore::new(config.lan.peer_timeout_secs)), forwarding_rules, upstream, timeout: Duration::from_millis(config.upstream.timeout_ms), @@ -161,6 +162,10 @@ async fn main() -> numa::Result<()> { }; eprintln!("\x1b[38;2;192;98;58m ║\x1b[0m \x1b[38;2;107;124;78mProxy\x1b[0m {:<30}\x1b[38;2;192;98;58m║\x1b[0m", schemes); } + if config.lan.enabled { + eprintln!("\x1b[38;2;192;98;58m ║\x1b[0m \x1b[38;2;107;124;78mLAN\x1b[0m {:<30}\x1b[38;2;192;98;58m║\x1b[0m", + format!("{}:{}", config.lan.multicast_group, config.lan.port)); + } if !ctx.forwarding_rules.is_empty() { eprintln!("\x1b[38;2;192;98;58m ║\x1b[0m \x1b[38;2;107;124;78mRouting\x1b[0m {:<30}\x1b[38;2;192;98;58m║\x1b[0m", format!("{} conditional rules", ctx.forwarding_rules.len())); @@ -235,6 +240,15 @@ async fn main() -> numa::Result<()> { } } + // Spawn LAN service discovery + if config.lan.enabled { + let lan_ctx = Arc::clone(&ctx); + let lan_config = config.lan.clone(); + tokio::spawn(async move { + numa::lan::start_lan_discovery(lan_ctx, &lan_config).await; + }); + } + // UDP DNS listener #[allow(clippy::infinite_loop)] loop { diff --git a/src/proxy.rs b/src/proxy.rs index 761a0d1..af9ca5c 100644 --- a/src/proxy.rs +++ b/src/proxy.rs @@ -135,11 +135,15 @@ async fn proxy_handler(State(state): State, req: Request) -> axum::r } }; - let target_port = { + let (target_host, target_port) = { let store = state.ctx.services.lock().unwrap(); - match store.lookup(&service_name) { - Some(entry) => entry.target_port, - None => { + if let Some(entry) = store.lookup(&service_name) { + ("localhost".to_string(), entry.target_port) + } else { + let mut peers = state.ctx.lan_peers.lock().unwrap(); + match peers.lookup(&service_name) { + Some((ip, port)) => (ip.to_string(), port), + None => { return ( StatusCode::NOT_FOUND, [(hyper::header::CONTENT_TYPE, "text/html; charset=utf-8")], @@ -259,6 +263,7 @@ pre .str {{ color: #d48a5a }} ), ) .into_response() + } } } }; @@ -268,7 +273,7 @@ pre .str {{ color: #d48a5a }} .path_and_query() .map(|pq| pq.as_str()) .unwrap_or("/"); - let target_uri: hyper::Uri = format!("http://localhost:{}{}", target_port, path_and_query) + let target_uri: hyper::Uri = format!("http://{}:{}{}", target_host, target_port, path_and_query) .parse() .unwrap();