DynDNS: Automatic External IP Tracking & Periodic Host Resolution

components/addressmanager/src/dyndns_extender.rs

@@ -0,0 +1,116 @@
+use std::{net::IpAddr, sync::{Arc}, time::Duration};
+use parking_lot::Mutex;
+use kaspa_core::{info, debug, warn, trace, task::{tick::{TickService, TickReason}, service::{AsyncService, AsyncServiceFuture}}};
+use crate::{NetAddress, AddressManager};
+use kaspa_utils::networking::IpAddress;
+use kaspa_consensus_core::config::{Config, IpVersionMode};
+use std::net::ToSocketAddrs;
+
+pub const SERVICE_NAME: &str = "dyndns-extender";
+
+// Simplistic resolver trait to allow mocking in tests later
+trait DynResolver: Send + Sync {
+    fn resolve(&self, host: &str) -> std::io::Result<Vec<IpAddr>>;
+}
+
+struct DefaultResolver;
+impl DynResolver for DefaultResolver {
+    fn resolve(&self, host: &str) -> std::io::Result<Vec<IpAddr>> { Ok((host, 0).to_socket_addrs()?.map(|sa| sa.ip()).collect()) }
+}
+
+pub struct DynDnsExtender {
+    tick_service: Arc<TickService>,
+    address_manager: Arc<Mutex<AddressManager>>,
+    host: String,
+    min_refresh: Duration,
+    max_refresh: Duration,
+    ip_mode: IpVersionMode,
+    resolver: Box<dyn DynResolver>,
+    last_ip: Arc<Mutex<Option<IpAddr>>>,
+}
+
+impl DynDnsExtender {
+    pub fn new(config: Arc<Config>, am: Arc<Mutex<AddressManager>>, tick_service: Arc<TickService>, initial_external_ip: Option<IpAddr>) -> Option<Self> {
+        let host = config.external_dyndns_host.clone()?; // only build if host provided
+
+        let instance = Self {
+            tick_service,
+            address_manager: am.clone(),
+            min_refresh: Duration::from_secs(config.external_dyndns_min_refresh_sec),
+            max_refresh: Duration::from_secs(config.external_dyndns_max_refresh_sec),
+            ip_mode: config.external_dyndns_ip_version,
+            host,
+            resolver: Box::new(DefaultResolver),
+            last_ip: Arc::new(Mutex::new(initial_external_ip)),
+        };
+
+        Some(instance)
+    }
+
+    fn pick_ip(&self, mut ips: Vec<IpAddr>) -> Option<IpAddr> {
+        // filter publics
+        ips.retain(|ip| IpAddress::new(*ip).is_publicly_routable());
+        if ips.is_empty() { return None; }
+        match self.ip_mode {
+            IpVersionMode::Ipv4 => ips.into_iter().find(|ip| matches!(ip, IpAddr::V4(_))),
+            IpVersionMode::Ipv6 => ips.into_iter().find(|ip| matches!(ip, IpAddr::V6(_))),
+            IpVersionMode::Auto => {
+                if let Some(v4) = ips.iter().cloned().find(|ip| matches!(ip, IpAddr::V4(_))) { return Some(v4); }
+                ips.into_iter().next()
+            }
+        }
+    }
+
+    async fn worker(&self) {
+        info!("[DynDNS] Starting dyndns resolver for host {}", self.host);
+        let mut interval = self.min_refresh; // adaptive later
+        loop {
+            match self.tick_service.tick(interval).await {
+                TickReason::Shutdown => break,
+                TickReason::Wakeup => {}
+            }
+            match self.resolver.resolve(&self.host) {
+                Ok(ips) => {
+                    debug!("[DynDNS] Resolved {} -> {:?}", self.host, ips);
+                    let picked = self.pick_ip(ips);
+                    if let Some(new_ip) = picked {
+                        let mut last_guard = self.last_ip.lock();
+                        if Some(new_ip) != *last_guard {
+                            let old_ip = *last_guard;
+                            *last_guard = Some(new_ip);
+                            drop(last_guard);
+                            self.apply_new_ip(new_ip, old_ip);
+                        }
+                        interval = self.min_refresh; // reset
+                    } else {
+                        warn!("[DynDNS] No public IP obtained for {}", self.host);
+                        interval = std::cmp::min(interval * 2, self.max_refresh);
+                    }
+                }
+                Err(e) => {
+                    warn!("[DynDNS] Resolve failed for {}: {e}", self.host);
+                    interval = std::cmp::min(interval * 2, self.max_refresh);
+                }
+            }
+        }
+        trace!("{SERVICE_NAME} worker exiting");
+    }
+
+    fn apply_new_ip(&self, new_ip: IpAddr, old_ip: Option<IpAddr>) {
+        info!("[DynDNS] External IP changed {:?} -> {}", old_ip, new_ip);
+        let mut am = self.address_manager.lock();
+        let port = am.best_local_address().map(|a| a.port).unwrap_or_else(|| am.config.default_p2p_port());
+        let net = NetAddress::new(new_ip.into(), port);
+        am.set_best_local_address(net);
+        let sinks = am.clone_external_ip_change_sinks();
+        drop(am);
+        for sink in sinks { let s = sink.clone(); tokio::spawn(async move { s.on_external_ip_changed(new_ip, old_ip); }); }
+    }
+}
+
+impl AsyncService for DynDnsExtender {
+    fn ident(self: Arc<Self>) -> &'static str { SERVICE_NAME }
+    fn start(self: Arc<Self>) -> AsyncServiceFuture { Box::pin(async move { self.worker().await; Ok(()) }) }
+    fn signal_exit(self: Arc<Self>) { trace!("sending an exit signal to {}", SERVICE_NAME); }
+    fn stop(self: Arc<Self>) -> AsyncServiceFuture { Box::pin(async move { trace!("{} stopped", SERVICE_NAME); Ok(()) }) }
+}

components/addressmanager/src/lib.rs

@@ -1,10 +1,12 @@
+mod dyndns_extender;
 mod port_mapping_extender;
 mod stores;
 extern crate self as address_manager;
 
 use std::{collections::HashSet, iter, net::SocketAddr, sync::Arc, time::Duration};
 
 use address_manager::port_mapping_extender::Extender;
+use dyndns_extender::DynDnsExtender;
 use igd_next::{
     self as igd, aio::tokio::Tokio, AddAnyPortError, AddPortError, Gateway, GetExternalIpError, GetGenericPortMappingEntryError,
     SearchError,
@@ -13,7 +15,7 @@ use itertools::{
     Either::{Left, Right},
     Itertools,
 };
-use kaspa_consensus_core::config::Config;
+use kaspa_consensus_core::config::{Config, IpVersionMode};
 use kaspa_core::{debug, info, task::tick::TickService, time::unix_now, warn};
 use kaspa_database::prelude::{CachePolicy, StoreResultExtensions, DB};
 use kaspa_utils::networking::IpAddress;
@@ -24,6 +26,10 @@ use thiserror::Error;
 
 pub use stores::NetAddress;
 
+pub trait ExternalIpChangeSink: Send + Sync {
+    fn on_external_ip_changed(&self, new_ip: std::net::IpAddr, old_ip: Option<std::net::IpAddr>);
+}
+
 const MAX_ADDRESSES: usize = 4096;
 const MAX_CONNECTION_FAILED_COUNT: u64 = 3;
 
@@ -56,35 +62,112 @@ pub struct AddressManager {
     address_store: address_store_with_cache::Store,
     config: Arc<Config>,
     local_net_addresses: Vec<NetAddress>,
+    external_ip_change_sinks: Vec<Arc<dyn ExternalIpChangeSink>>,
 }
 
 impl AddressManager {
-    pub fn new(config: Arc<Config>, db: Arc<DB>, tick_service: Arc<TickService>) -> (Arc<Mutex<Self>>, Option<Extender>) {
-        let mut instance = Self {
+    pub fn new(
+        config: Arc<Config>,
+        db: Arc<DB>,
+        tick_service: Arc<TickService>,
+    ) -> (Arc<Mutex<Self>>, Option<Extender>, Option<DynDnsExtender>) {
+        let instance = Self {
             banned_address_store: DbBannedAddressesStore::new(db.clone(), CachePolicy::Count(MAX_ADDRESSES)),
             address_store: address_store_with_cache::new(db),
             local_net_addresses: Vec::new(),
+            external_ip_change_sinks: Vec::new(),
             config,
         };
 
-        let extender = instance.init_local_addresses(tick_service);
+        let am = Arc::new(Mutex::new(instance));
+
+        let extender = Self::init_local_addresses(&am, tick_service.clone());
+        let dyndns_extender = if extender.is_none() {
+            Self::try_initial_dyndns_resolve(&am, tick_service.clone())
+        } else {
+            debug!("[AddrMan] UPnP extender active; DynDNS skipped");
+            None
+        };
+        // Note: initial DynDNS seed handled above when applicable
+        debug!(
+            "[AddrMan] Exit AddressManager::new (upnp_extender={} dyndns_extender={})",
+            extender.is_some(),
+            dyndns_extender.is_some()
+        );
+        (am, extender, dyndns_extender)
+    }
+
+    fn try_initial_dyndns_resolve(am: &Arc<Mutex<Self>>, tick_service: Arc<TickService>) -> Option<DynDnsExtender> {
+        // Only attempt if a DynDNS host is configured
+        let host_opt = am.lock().config.external_dyndns_host.clone();
+        let Some(host) = host_opt else { return None };
+        let ip_mode = am.lock().config.external_dyndns_ip_version;
+        let mut initial_ip: Option<std::net::IpAddr> = None;
+
+        debug!("[AddrMan] Performing minimal initial DynDNS resolve for host {}", host);
+        // DNS resolution outside lock
+        let result: std::io::Result<Vec<std::net::IpAddr>> = (|| {
+            use std::net::ToSocketAddrs;
+            (host.as_str(), 0).to_socket_addrs().map(|it| it.map(|sa| sa.ip()).collect())
+        })();
+        match result {
+            Ok(mut ips) => {
+                ips.retain(|ip| IpAddress::new(*ip).is_publicly_routable());
+                let selected = match ip_mode {
+                    IpVersionMode::Ipv4 => ips.iter().cloned().find(|ip| matches!(ip, std::net::IpAddr::V4(_))),
+                    IpVersionMode::Ipv6 => ips.iter().cloned().find(|ip| matches!(ip, std::net::IpAddr::V6(_))),
+                    IpVersionMode::Auto => {
+                        if let Some(v4) = ips.iter().cloned().find(|ip| matches!(ip, std::net::IpAddr::V4(_))) {
+                            Some(v4)
+                        } else {
+                            ips.get(0).cloned()
+                        }
+                    }
+                };
+                if let Some(ip) = selected {
+                    initial_ip = Some(ip);
+                    let mut guard = am.lock();
+                    let port = guard.config.default_p2p_port();
+                    guard.set_best_local_address(NetAddress::new(ip.into(), port));
+                    debug!("[AddrMan] Initial DynDNS external IP set to {}:{}", ip, port);
+                } else {
+                    debug!("[AddrMan] Initial DynDNS resolve returned no public addresses");
+                }
+            }
+            Err(e) => debug!("[AddrMan] Initial DynDNS resolve failed: {e}"),
+        }
+
+        let extender = DynDnsExtender::new(am.lock().config.clone(), am.clone(), tick_service, initial_ip);
+        if extender.is_some() {
+            debug!("[AddrMan] DynDnsExtender constructed");
+        } else {
+            debug!("[AddrMan] DynDnsExtender NOT constructed (unexpected None)");
+        }
+        extender
+    }
+
+    pub fn register_external_ip_change_sink(&mut self, sink: Arc<dyn ExternalIpChangeSink>) {
+        self.external_ip_change_sinks.push(sink);
+    }
 
-        (Arc::new(Mutex::new(instance)), extender)
+    pub fn clone_external_ip_change_sinks(&self) -> Vec<Arc<dyn ExternalIpChangeSink>> {
+        self.external_ip_change_sinks.clone()
     }
 
-    fn init_local_addresses(&mut self, tick_service: Arc<TickService>) -> Option<Extender> {
-        self.local_net_addresses = self.local_addresses().collect();
+    fn init_local_addresses(this: &Arc<Mutex<Self>>, tick_service: Arc<TickService>) -> Option<Extender> {
+        let mut me = this.lock();
+        me.local_net_addresses = me.local_addresses().collect();
 
-        let extender = if self.local_net_addresses.is_empty() && !self.config.disable_upnp {
-            let (net_address, ExtendHelper { gateway, local_addr, external_port }) = match self.upnp() {
+        let extender = if me.local_net_addresses.is_empty() && !me.config.disable_upnp {
+            let (net_address, ExtendHelper { gateway, local_addr, external_port }) = match me.upnp() {
                 Err(err) => {
                     warn!("[UPnP] Error adding port mapping: {err}");
                     return None;
                 }
                 Ok(None) => return None,
                 Ok(Some((net_address, extend_helper))) => (net_address, extend_helper),
             };
-            self.local_net_addresses.push(net_address);
+            me.local_net_addresses.push(net_address);
 
             let gateway: igd_next::aio::Gateway<Tokio> = igd_next::aio::Gateway {
                 addr: gateway.addr,
@@ -101,12 +184,14 @@ impl AddressManager {
                 gateway,
                 external_port,
                 local_addr,
+                Arc::clone(this),
+                Some(net_address.ip.into()),
             ))
         } else {
             None
         };
 
-        self.local_net_addresses.iter().for_each(|net_addr| {
+        me.local_net_addresses.iter().for_each(|net_addr| {
             info!("Publicly routable local address {} added to store", net_addr);
         });
         extender
@@ -142,12 +227,24 @@ impl AddressManager {
                 return Left(Right(iter::empty()));
             };
             // TODO: Add Check IPv4 or IPv6 match from Go code
-            Right(network_interfaces.into_iter().map(|(_, ip)| IpAddress::from(ip)).filter(|&ip| ip.is_publicly_routable()).map(
-                |ip| {
-                    info!("Publicly routable local address found: {}", ip);
-                    NetAddress::new(ip, self.config.default_p2p_port())
-                },
-            ))
+            Right(
+                network_interfaces
+                    .into_iter()
+                    .map(|(_, ip)| IpAddress::from(ip))
+                    .filter(|ip| {
+                        if self.config.disable_ipv6_interface_discovery {
+                            // Skip IPv6 during automatic discovery if the flag is set
+                            !matches!(**ip, std::net::IpAddr::V6(_))
+                        } else {
+                            true
+                        }
+                    })
+                    .filter(|&ip| ip.is_publicly_routable())
+                    .map(|ip| {
+                        info!("Publicly routable local address found: {}", ip);
+                        NetAddress::new(ip, self.config.default_p2p_port())
+                    }),
+            )
         } else {
             Left(Right(iter::empty()))
         }
@@ -251,6 +348,14 @@ impl AddressManager {
         }
     }
 
+    pub fn set_best_local_address(&mut self, address: NetAddress) {
+        if self.local_net_addresses.is_empty() {
+            self.local_net_addresses.push(address);
+        } else {
+            self.local_net_addresses[0] = address;
+        }
+    }
+
     pub fn add_address(&mut self, address: NetAddress) {
         if address.ip.is_loopback() || address.ip.is_unspecified() {
             debug!("[Address manager] skipping local address {}", address.ip);
@@ -548,7 +653,7 @@ mod address_store_with_cache {
 
             let db = create_temp_db!(ConnBuilder::default().with_files_limit(10));
             let config = Config::new(SIMNET_PARAMS);
-            let (am, _) = AddressManager::new(Arc::new(config), db.1, Arc::new(TickService::default()));
+            let (am, _, _) = AddressManager::new(Arc::new(config), db.1, Arc::new(TickService::default()));
 
             let mut am_guard = am.lock();