Merge pull request #95 from razvandimescu/fix/forwarding-precedes-special-use

fix: forwarding rules override special-use NXDOMAIN

src/api.rs

@@ -1020,53 +1020,10 @@ mod tests {
     use super::*;
     use axum::body::Body;
     use http::Request;
-    use std::sync::{Mutex, RwLock};
     use tower::ServiceExt;
 
     async fn test_ctx() -> Arc<ServerCtx> {
-        let socket = tokio::net::UdpSocket::bind("127.0.0.1:0").await.unwrap();
+        Arc::new(crate::testutil::test_ctx().await)
-        Arc::new(ServerCtx {
-            socket,
-            zone_map: std::collections::HashMap::new(),
-            cache: RwLock::new(crate::cache::DnsCache::new(100, 60, 86400)),
-            refreshing: Mutex::new(std::collections::HashSet::new()),
-            stats: Mutex::new(crate::stats::ServerStats::new()),
-            overrides: RwLock::new(crate::override_store::OverrideStore::new()),
-            blocklist: RwLock::new(crate::blocklist::BlocklistStore::new()),
-            query_log: Mutex::new(crate::query_log::QueryLog::new(100)),
-            services: Mutex::new(crate::service_store::ServiceStore::new()),
-            lan_peers: Mutex::new(crate::lan::PeerStore::new(90)),
-            forwarding_rules: Vec::new(),
-            upstream_pool: Mutex::new(crate::forward::UpstreamPool::new(
-                vec![crate::forward::Upstream::Udp(
-                    "127.0.0.1:53".parse().unwrap(),
-                )],
-                vec![],
-            )),
-            upstream_auto: false,
-            upstream_port: 53,
-            lan_ip: Mutex::new(std::net::Ipv4Addr::LOCALHOST),
-            timeout: std::time::Duration::from_secs(3),
-            hedge_delay: std::time::Duration::ZERO,
-            proxy_tld: "numa".to_string(),
-            proxy_tld_suffix: ".numa".to_string(),
-            lan_enabled: false,
-            config_path: "/tmp/test-numa.toml".to_string(),
-            config_found: false,
-            config_dir: std::path::PathBuf::from("/tmp"),
-            data_dir: std::path::PathBuf::from("/tmp"),
-            tls_config: None,
-            upstream_mode: crate::config::UpstreamMode::Forward,
-            root_hints: Vec::new(),
-            srtt: RwLock::new(crate::srtt::SrttCache::new(true)),
-            inflight: Mutex::new(std::collections::HashMap::new()),
-            dnssec_enabled: false,
-            dnssec_strict: false,
-            health_meta: crate::health::HealthMeta::test_fixture(),
-            ca_pem: None,
-            mobile_enabled: false,
-            mobile_port: 8765,
-        })
     }
 
     #[tokio::test]

src/ctx.rs

@@ -88,7 +88,7 @@ pub async fn resolve_query(
     src_addr: SocketAddr,
     ctx: &Arc<ServerCtx>,
     transport: Transport,
-) -> crate::Result<BytePacketBuffer> {
+) -> crate::Result<(BytePacketBuffer, QueryPath)> {
     let start = Instant::now();
 
     let (qname, qtype) = match query.questions.first() {
@@ -96,7 +96,8 @@ pub async fn resolve_query(
         None => return Err("empty question section".into()),
     };
 
-    // Pipeline: overrides -> .tld interception -> blocklist -> local zones -> cache -> upstream
+    // Pipeline: overrides -> .localhost -> local zones -> special-use (unless forwarded)
+    //        -> .tld proxy -> blocklist -> cache -> forwarding -> recursive/upstream
     // Each lock is scoped to avoid holding MutexGuard across await points.
     let (response, path, dnssec) = {
         let override_record = ctx.overrides.read().unwrap().lookup(&qname);
@@ -119,8 +120,10 @@ pub async fn resolve_query(
             let mut resp = DnsPacket::response_from(&query, ResultCode::NOERROR);
             resp.answers = records.clone();
             (resp, QueryPath::Local, DnssecStatus::Indeterminate)
-        } else if is_special_use_domain(&qname) {
+        } else if is_special_use_domain(&qname)
-            // RFC 6761/8880: private PTR, DDR, NAT64 — answer locally
+            && crate::system_dns::match_forwarding_rule(&qname, &ctx.forwarding_rules).is_none()
+        {
+            // RFC 6761/8880: answer locally unless a forwarding rule covers this zone.
             let resp = special_use_response(&query, &qname, qtype);
             (resp, QueryPath::Local, DnssecStatus::Indeterminate)
         } else if !ctx.proxy_tld_suffix.is_empty()
@@ -373,7 +376,7 @@ pub async fn resolve_query(
         dnssec,
     });
 
-    Ok(resp_buffer)
+    Ok((resp_buffer, path))
 }
 
 fn cache_and_parse(
@@ -457,7 +460,7 @@ pub async fn handle_query(
         }
     };
     match resolve_query(query, &buffer.buf[..raw_len], src_addr, ctx, transport).await {
-        Ok(resp_buffer) => {
+        Ok((resp_buffer, _)) => {
             ctx.socket.send_to(resp_buffer.filled(), src_addr).await?;
         }
         Err(e) => {
@@ -1036,4 +1039,216 @@ mod tests {
             "error message must be preserved for logging"
         );
     }
+
+    // ---- Full-pipeline resolve_query tests ----
+
+    /// Send a query through the full resolve_query pipeline and return
+    /// the parsed response + query path.
+    async fn resolve_in_test(
+        ctx: &Arc<ServerCtx>,
+        domain: &str,
+        qtype: QueryType,
+    ) -> (DnsPacket, QueryPath) {
+        let query = DnsPacket::query(0xBEEF, domain, qtype);
+        let mut buf = BytePacketBuffer::new();
+        query.write(&mut buf).unwrap();
+        let raw = &buf.buf[..buf.pos];
+        let src: SocketAddr = "127.0.0.1:1234".parse().unwrap();
+
+        let (resp_buf, path) = resolve_query(query, raw, src, ctx, Transport::Udp)
+            .await
+            .unwrap();
+
+        let mut resp_parse_buf = BytePacketBuffer::from_bytes(resp_buf.filled());
+        let resp = DnsPacket::from_buffer(&mut resp_parse_buf).unwrap();
+        (resp, path)
+    }
+
+    #[tokio::test]
+    async fn special_use_private_ptr_returns_nxdomain() {
+        let ctx = Arc::new(crate::testutil::test_ctx().await);
+        let (resp, path) =
+            resolve_in_test(&ctx, "153.188.168.192.in-addr.arpa", QueryType::PTR).await;
+        assert_eq!(path, QueryPath::Local);
+        assert_eq!(resp.header.rescode, ResultCode::NXDOMAIN);
+    }
+
+    #[tokio::test]
+    async fn forwarding_rule_overrides_special_use_domain() {
+        let mut resp = DnsPacket::new();
+        resp.header.response = true;
+        resp.header.rescode = ResultCode::NOERROR;
+        let upstream_addr = crate::testutil::mock_upstream(resp).await;
+
+        let mut ctx = crate::testutil::test_ctx().await;
+        ctx.forwarding_rules = vec![ForwardingRule::new(
+            "168.192.in-addr.arpa".to_string(),
+            upstream_addr,
+        )];
+        let ctx = Arc::new(ctx);
+
+        let (resp, path) =
+            resolve_in_test(&ctx, "153.188.168.192.in-addr.arpa", QueryType::PTR).await;
+
+        assert_eq!(
+            path,
+            QueryPath::Forwarded,
+            "forwarding rule must take precedence over special-use NXDOMAIN"
+        );
+        assert_eq!(resp.header.rescode, ResultCode::NOERROR);
+    }
+
+    #[tokio::test]
+    async fn pipeline_override_takes_precedence() {
+        let ctx = crate::testutil::test_ctx().await;
+        ctx.overrides
+            .write()
+            .unwrap()
+            .insert("override.test", "1.2.3.4", 60, None)
+            .unwrap();
+        let ctx = Arc::new(ctx);
+
+        let (resp, path) = resolve_in_test(&ctx, "override.test", QueryType::A).await;
+        assert_eq!(path, QueryPath::Overridden);
+        assert_eq!(resp.header.rescode, ResultCode::NOERROR);
+        assert_eq!(resp.answers.len(), 1);
+    }
+
+    #[tokio::test]
+    async fn pipeline_localhost_resolves_to_loopback() {
+        let ctx = Arc::new(crate::testutil::test_ctx().await);
+
+        let (resp, path) = resolve_in_test(&ctx, "localhost", QueryType::A).await;
+        assert_eq!(path, QueryPath::Local);
+        assert_eq!(resp.header.rescode, ResultCode::NOERROR);
+        match &resp.answers[0] {
+            DnsRecord::A { addr, .. } => assert_eq!(*addr, Ipv4Addr::LOCALHOST),
+            other => panic!("expected A record, got {:?}", other),
+        }
+    }
+
+    #[tokio::test]
+    async fn pipeline_localhost_subdomain_resolves_to_loopback() {
+        let ctx = Arc::new(crate::testutil::test_ctx().await);
+
+        let (resp, path) = resolve_in_test(&ctx, "app.localhost", QueryType::A).await;
+        assert_eq!(path, QueryPath::Local);
+        assert_eq!(resp.header.rescode, ResultCode::NOERROR);
+        match &resp.answers[0] {
+            DnsRecord::A { addr, .. } => assert_eq!(*addr, Ipv4Addr::LOCALHOST),
+            other => panic!("expected A record, got {:?}", other),
+        }
+    }
+
+    #[tokio::test]
+    async fn pipeline_local_zone_returns_configured_record() {
+        let mut ctx = crate::testutil::test_ctx().await;
+        let mut inner = HashMap::new();
+        inner.insert(
+            QueryType::A,
+            vec![DnsRecord::A {
+                domain: "myapp.test".to_string(),
+                addr: Ipv4Addr::new(10, 0, 0, 42),
+                ttl: 300,
+            }],
+        );
+        ctx.zone_map.insert("myapp.test".to_string(), inner);
+        let ctx = Arc::new(ctx);
+
+        let (resp, path) = resolve_in_test(&ctx, "myapp.test", QueryType::A).await;
+        assert_eq!(path, QueryPath::Local);
+        assert_eq!(resp.header.rescode, ResultCode::NOERROR);
+        match &resp.answers[0] {
+            DnsRecord::A { addr, .. } => assert_eq!(*addr, Ipv4Addr::new(10, 0, 0, 42)),
+            other => panic!("expected A record, got {:?}", other),
+        }
+    }
+
+    #[tokio::test]
+    async fn pipeline_tld_proxy_resolves_service() {
+        let ctx = crate::testutil::test_ctx().await;
+        ctx.services.lock().unwrap().insert("grafana", 3000);
+        let ctx = Arc::new(ctx);
+
+        let (resp, path) = resolve_in_test(&ctx, "grafana.numa", QueryType::A).await;
+        assert_eq!(path, QueryPath::Local);
+        assert_eq!(resp.header.rescode, ResultCode::NOERROR);
+        match &resp.answers[0] {
+            DnsRecord::A { addr, .. } => assert_eq!(*addr, Ipv4Addr::LOCALHOST),
+            other => panic!("expected A record, got {:?}", other),
+        }
+    }
+
+    #[tokio::test]
+    async fn pipeline_blocklist_sinkhole() {
+        let ctx = crate::testutil::test_ctx().await;
+        let mut domains = std::collections::HashSet::new();
+        domains.insert("ads.tracker.test".to_string());
+        ctx.blocklist.write().unwrap().swap_domains(domains, vec![]);
+        let ctx = Arc::new(ctx);
+
+        let (resp, path) = resolve_in_test(&ctx, "ads.tracker.test", QueryType::A).await;
+        assert_eq!(path, QueryPath::Blocked);
+        assert_eq!(resp.header.rescode, ResultCode::NOERROR);
+        match &resp.answers[0] {
+            DnsRecord::A { addr, .. } => assert_eq!(*addr, Ipv4Addr::UNSPECIFIED),
+            other => panic!("expected sinkhole A record, got {:?}", other),
+        }
+    }
+
+    #[tokio::test]
+    async fn pipeline_cache_hit() {
+        let ctx = Arc::new(crate::testutil::test_ctx().await);
+
+        // Pre-populate cache with a response
+        let mut pkt = DnsPacket::new();
+        pkt.header.response = true;
+        pkt.header.rescode = ResultCode::NOERROR;
+        pkt.questions.push(crate::question::DnsQuestion {
+            name: "cached.test".to_string(),
+            qtype: QueryType::A,
+        });
+        pkt.answers.push(DnsRecord::A {
+            domain: "cached.test".to_string(),
+            addr: Ipv4Addr::new(5, 5, 5, 5),
+            ttl: 3600,
+        });
+        ctx.cache
+            .write()
+            .unwrap()
+            .insert("cached.test", QueryType::A, &pkt);
+
+        let (resp, path) = resolve_in_test(&ctx, "cached.test", QueryType::A).await;
+        assert_eq!(path, QueryPath::Cached);
+        assert_eq!(resp.header.rescode, ResultCode::NOERROR);
+    }
+
+    #[tokio::test]
+    async fn pipeline_forwarding_returns_upstream_answer() {
+        let mut upstream_resp = DnsPacket::new();
+        upstream_resp.header.response = true;
+        upstream_resp.header.rescode = ResultCode::NOERROR;
+        upstream_resp.answers.push(DnsRecord::A {
+            domain: "internal.corp".to_string(),
+            addr: Ipv4Addr::new(10, 1, 2, 3),
+            ttl: 600,
+        });
+        let upstream_addr = crate::testutil::mock_upstream(upstream_resp).await;
+
+        let mut ctx = crate::testutil::test_ctx().await;
+        ctx.forwarding_rules = vec![ForwardingRule::new("corp".to_string(), upstream_addr)];
+        let ctx = Arc::new(ctx);
+
+        let (resp, path) = resolve_in_test(&ctx, "internal.corp", QueryType::A).await;
+        assert_eq!(path, QueryPath::Forwarded);
+        assert_eq!(resp.header.rescode, ResultCode::NOERROR);
+        assert_eq!(resp.answers.len(), 1);
+        match &resp.answers[0] {
+            DnsRecord::A { domain, addr, .. } => {
+                assert_eq!(domain, "internal.corp");
+                assert_eq!(*addr, Ipv4Addr::new(10, 1, 2, 3));
+            }
+            other => panic!("expected A record, got {:?}", other),
+        }
+    }
 }

src/doh.rs

@@ -113,7 +113,7 @@ async fn resolve_doh(
     let questions = query.questions.clone();
 
     match resolve_query(query, dns_bytes, src, ctx, Transport::Doh).await {
-        Ok(resp_buffer) => {
+        Ok((resp_buffer, _)) => {
             let min_ttl = extract_min_ttl(resp_buffer.filled());
             dns_response(resp_buffer.filled(), min_ttl)
         }

src/dot.rs

@@ -211,7 +211,7 @@ async fn handle_dot_connection<S>(
         )
         .await
         {
-            Ok(resp_buffer) => {
+            Ok((resp_buffer, _)) => {
                 if write_framed(&mut stream, resp_buffer.filled())
                     .await
                     .is_err()
@@ -279,7 +279,7 @@ where
 mod tests {
     use super::*;
     use std::collections::HashMap;
-    use std::sync::{Mutex, RwLock};
+    use std::sync::Mutex;
 
     use rcgen::{CertificateParams, DnType, KeyPair};
     use rustls::pki_types::{CertificateDer, PrivateKeyDer, PrivatePkcs8KeyDer, ServerName};
@@ -344,63 +344,29 @@ mod tests {
     async fn spawn_dot_server() -> (SocketAddr, CertificateDer<'static>) {
         let (server_tls, cert_der) = test_tls_configs();
 
-        let socket = tokio::net::UdpSocket::bind("127.0.0.1:0").await.unwrap();
+        let upstream_addr = crate::testutil::blackhole_upstream();
-        // Bind an unresponsive upstream and leak it so it lives for the test duration.
+
-        let blackhole = Box::leak(Box::new(std::net::UdpSocket::bind("127.0.0.1:0").unwrap()));
+        let mut ctx = crate::testutil::test_ctx().await;
-        let upstream_addr = blackhole.local_addr().unwrap();
+        ctx.zone_map = {
-        let ctx = Arc::new(ServerCtx {
+            let mut m = HashMap::new();
-            socket,
+            let mut inner = HashMap::new();
-            zone_map: {
+            inner.insert(
-                let mut m = HashMap::new();
+                QueryType::A,
-                let mut inner = HashMap::new();
+                vec![DnsRecord::A {
-                inner.insert(
+                    domain: "dot-test.example".to_string(),
-                    QueryType::A,
+                    addr: std::net::Ipv4Addr::new(10, 0, 0, 1),
-                    vec![DnsRecord::A {
+                    ttl: 300,
-                        domain: "dot-test.example".to_string(),
+                }],
-                        addr: std::net::Ipv4Addr::new(10, 0, 0, 1),
+            );
-                        ttl: 300,
+            m.insert("dot-test.example".to_string(), inner);
-                    }],
+            m
-                );
+        };
-                m.insert("dot-test.example".to_string(), inner);
+        ctx.upstream_pool = Mutex::new(crate::forward::UpstreamPool::new(
-                m
+            vec![crate::forward::Upstream::Udp(upstream_addr)],
-            },
+            vec![],
-            cache: RwLock::new(crate::cache::DnsCache::new(100, 60, 86400)),
+        ));
-            refreshing: Mutex::new(std::collections::HashSet::new()),
+        ctx.tls_config = Some(arc_swap::ArcSwap::from(server_tls));
-            stats: Mutex::new(crate::stats::ServerStats::new()),
+        let ctx = Arc::new(ctx);
-            overrides: RwLock::new(crate::override_store::OverrideStore::new()),
-            blocklist: RwLock::new(crate::blocklist::BlocklistStore::new()),
-            query_log: Mutex::new(crate::query_log::QueryLog::new(100)),
-            services: Mutex::new(crate::service_store::ServiceStore::new()),
-            lan_peers: Mutex::new(crate::lan::PeerStore::new(90)),
-            forwarding_rules: Vec::new(),
-            upstream_pool: Mutex::new(crate::forward::UpstreamPool::new(
-                vec![crate::forward::Upstream::Udp(upstream_addr)],
-                vec![],
-            )),
-            upstream_auto: false,
-            upstream_port: 53,
-            lan_ip: Mutex::new(std::net::Ipv4Addr::LOCALHOST),
-            timeout: Duration::from_millis(200),
-            hedge_delay: Duration::ZERO,
-            proxy_tld: "numa".to_string(),
-            proxy_tld_suffix: ".numa".to_string(),
-            lan_enabled: false,
-            config_path: String::new(),
-            config_found: false,
-            config_dir: std::path::PathBuf::from("/tmp"),
-            data_dir: std::path::PathBuf::from("/tmp"),
-            tls_config: Some(arc_swap::ArcSwap::from(server_tls)),
-            upstream_mode: crate::config::UpstreamMode::Forward,
-            root_hints: Vec::new(),
-            srtt: RwLock::new(crate::srtt::SrttCache::new(true)),
-            inflight: Mutex::new(HashMap::new()),
-            dnssec_enabled: false,
-            dnssec_strict: false,
-            health_meta: crate::health::HealthMeta::test_fixture(),
-            ca_pem: None,
-            mobile_enabled: false,
-            mobile_port: 8765,
-        });
 
         let listener = TcpListener::bind("127.0.0.1:0").await.unwrap();
         let addr = listener.local_addr().unwrap();

src/lib.rs

@@ -28,6 +28,9 @@ pub mod system_dns;
 pub mod tls;
 pub mod wire;
 
+#[cfg(test)]
+pub(crate) mod testutil;
+
 pub type Error = Box<dyn std::error::Error + Send + Sync>;
 pub type Result<T> = std::result::Result<T, Error>;
 

src/testutil.rs

@@ -0,0 +1,95 @@
+use std::collections::{HashMap, HashSet};
+use std::net::{Ipv4Addr, SocketAddr};
+use std::path::PathBuf;
+use std::sync::{Mutex, RwLock};
+use std::time::Duration;
+
+use tokio::net::UdpSocket;
+
+use crate::blocklist::BlocklistStore;
+use crate::buffer::BytePacketBuffer;
+use crate::cache::DnsCache;
+use crate::config::UpstreamMode;
+use crate::ctx::ServerCtx;
+use crate::forward::{Upstream, UpstreamPool};
+use crate::health::HealthMeta;
+use crate::lan::PeerStore;
+use crate::override_store::OverrideStore;
+use crate::packet::DnsPacket;
+use crate::query_log::QueryLog;
+use crate::service_store::ServiceStore;
+use crate::srtt::SrttCache;
+use crate::stats::ServerStats;
+/// Minimal `ServerCtx` for tests. Override fields after construction
+/// (all fields are `pub`), then wrap in `Arc`.
+pub async fn test_ctx() -> ServerCtx {
+    let socket = UdpSocket::bind("127.0.0.1:0").await.unwrap();
+    ServerCtx {
+        socket,
+        zone_map: HashMap::new(),
+        cache: RwLock::new(DnsCache::new(100, 60, 86400)),
+        refreshing: Mutex::new(HashSet::new()),
+        stats: Mutex::new(ServerStats::new()),
+        overrides: RwLock::new(OverrideStore::new()),
+        blocklist: RwLock::new(BlocklistStore::new()),
+        query_log: Mutex::new(QueryLog::new(100)),
+        services: Mutex::new(ServiceStore::new()),
+        lan_peers: Mutex::new(PeerStore::new(90)),
+        forwarding_rules: Vec::new(),
+        upstream_pool: Mutex::new(UpstreamPool::new(
+            vec![Upstream::Udp("127.0.0.1:53".parse().unwrap())],
+            vec![],
+        )),
+        upstream_auto: false,
+        upstream_port: 53,
+        lan_ip: Mutex::new(Ipv4Addr::LOCALHOST),
+        timeout: Duration::from_millis(200),
+        hedge_delay: Duration::ZERO,
+        proxy_tld: "numa".to_string(),
+        proxy_tld_suffix: ".numa".to_string(),
+        lan_enabled: false,
+        config_path: "/tmp/test-numa.toml".to_string(),
+        config_found: false,
+        config_dir: PathBuf::from("/tmp"),
+        data_dir: PathBuf::from("/tmp"),
+        tls_config: None,
+        upstream_mode: UpstreamMode::Forward,
+        root_hints: Vec::new(),
+        srtt: RwLock::new(SrttCache::new(true)),
+        inflight: Mutex::new(HashMap::new()),
+        dnssec_enabled: false,
+        dnssec_strict: false,
+        health_meta: HealthMeta::test_fixture(),
+        ca_pem: None,
+        mobile_enabled: false,
+        mobile_port: 8765,
+    }
+}
+
+/// Spawn a UDP socket that replies to the first DNS query with the given
+/// response packet (patching the query ID to match). Returns the socket address.
+pub async fn mock_upstream(response: DnsPacket) -> SocketAddr {
+    let sock = UdpSocket::bind("127.0.0.1:0").await.unwrap();
+    let addr = sock.local_addr().unwrap();
+    tokio::spawn(async move {
+        let mut buf = [0u8; 512];
+        let (_, src) = sock.recv_from(&mut buf).await.unwrap();
+        let query_id = u16::from_be_bytes([buf[0], buf[1]]);
+        let mut resp = response;
+        resp.header.id = query_id;
+        let mut out = BytePacketBuffer::new();
+        resp.write(&mut out).unwrap();
+        sock.send_to(out.filled(), src).await.unwrap();
+    });
+    addr
+}
+
+/// UDP socket that accepts connections but never replies.
+/// Useful as an upstream that triggers timeouts.
+pub fn blackhole_upstream() -> SocketAddr {
+    let sock = std::net::UdpSocket::bind("127.0.0.1:0").unwrap();
+    let addr = sock.local_addr().unwrap();
+    // Leak so it stays bound for the duration of the test process.
+    Box::leak(Box::new(sock));
+    addr
+}