Support RUST_LOG, enable UPnP portmapper and add NAT traversal logging

Previously, `tsunagi-cli` configured clap with a fixed default_value and
`env = "TSUNAGI_LOG"`, which caused `RUST_LOG` to be completely ignored.
In addition, `iroh` was built with `default-features = false` and lacked the
`"portmapper"` feature, which caused it to compile a stub client and disable
UPnP-IGD, PCP, and NAT-PMP port mapping. Furthermore, there was no visibility
into STUN address discovery, UPnP port mapping status, or QUIC transmission path
switching (hole punch vs relay).

Key improvements:
- Enable the `"portmapper"` feature on `iroh` in workspace Cargo.toml, pulling in
  `portmapper` and `igd-next` to actively request port mappings on local routers.
- In `crates/tsunagi-cli/src/main.rs`, support `RUST_LOG` with fallback precedence
  (`--log` > `TSUNAGI_LOG` > `RUST_LOG` > default filter). When debug or trace
  filtering is active, automatically enable `.with_target(true)` so users can see
  which subsystem emitted the log (e.g., portmapper, iroh::magicsock, tsunagi::net).
- In `crates/tsunagi/src/net.rs`, monitor `endpoint.watch_addr()` and
  `endpoint.home_relay_status()`. Emit `DEBUG` logs for local socket binding,
  discovered STUN reflexive/UPnP addresses, and relay connections. If no direct
  addresses are discovered after probe grace, emit a concise `WARN`.
- In `crates/tsunagi/src/agent/session.rs`, monitor connection `path_events()`
  to log when transmission paths are opened, closed, or selected (switching between
  relay and direct hole-punched paths), with bounded task winding down on shutdown.

Validation on Linux:
- cargo fmt --all -- --check passed.
- cargo clippy --locked --workspace --all-targets -- -D warnings passed.
- cargo test --locked --workspace --all-targets passed (349 tests passed).
- Live verification with `RUST_LOG=debug` confirmed SSDP broadcast to 239.255.255.250:1900,
  portmapper logs, STUN QAD discovery, and clean relay shutdown.

Cargo.lock

@@ -234,6 +234,18 @@ version = "1.1.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "1505bd5d3d116872e7271a6d4e16d81d0c8570876c8de68093a09ac269d8aac0"
 
+[[package]]
+name = "attohttpc"
+version = "0.30.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "16e2cdb6d5ed835199484bb92bb8b3edd526effe995c61732580439c1a67e2e9"
+dependencies = [
+ "base64 0.22.1",
+ "http",
+ "log",
+ "url",
+]
+
 [[package]]
 name = "autocfg"
 version = "1.5.1"
@@ -1112,6 +1124,12 @@ dependencies = [
  "spin 0.9.9",
 ]
 
+[[package]]
+name = "fnv"
+version = "1.0.7"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "3f9eec918d3f24069decb9af1554cad7c880e2da24a9afd88aca000531ab82c1"
+
 [[package]]
 name = "foldhash"
 version = "0.2.0"
@@ -1341,6 +1359,25 @@ dependencies = [
  "wasm-bindgen",
 ]
 
+[[package]]
+name = "h2"
+version = "0.4.19"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "ef8e5e5a340588f4452631496976cf8636d4a7ecf600239fdc27615d2530bc16"
+dependencies = [
+ "atomic-waker",
+ "bytes",
+ "fnv",
+ "futures-core",
+ "futures-sink",
+ "http",
+ "indexmap",
+ "slab",
+ "tokio",
+ "tokio-util",
+ "tracing",
+]
+
 [[package]]
 name = "hashbrown"
 version = "0.16.1"
@@ -1473,6 +1510,7 @@ dependencies = [
  "bytes",
  "futures-channel",
  "futures-core",
+ "h2",
  "http",
  "http-body",
  "httparse",
@@ -1656,6 +1694,26 @@ dependencies = [
  "icu_properties",
 ]
 
+[[package]]
+name = "igd-next"
+version = "0.17.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "de7238d487a9aff61f81b5ab41c0a841532a115a398b5fa92a2fadd0885e2581"
+dependencies = [
+ "attohttpc",
+ "bytes",
+ "futures",
+ "http",
+ "http-body-util",
+ "hyper",
+ "hyper-util",
+ "log",
+ "rand 0.10.3",
+ "tokio",
+ "url",
+ "xmltree",
+]
+
 [[package]]
 name = "indexmap"
 version = "2.14.2"
@@ -1748,6 +1806,7 @@ dependencies = [
  "papaya",
  "pin-project",
  "portable-atomic",
+ "portmapper",
  "rand 0.10.3",
  "reqwest",
  "rustc-hash",
@@ -2936,6 +2995,35 @@ dependencies = [
  "serde",
 ]
 
+[[package]]
+name = "portmapper"
+version = "0.19.3"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "ca97242f016e090a25330613bc2382aab65eb22f9149dbe84d8f8e711d49a530"
+dependencies = [
+ "base64 0.22.1",
+ "bytes",
+ "derive_more",
+ "hyper-util",
+ "igd-next",
+ "iroh-metrics",
+ "libc",
+ "n0-error",
+ "n0-future",
+ "netwatch",
+ "num_enum",
+ "rand 0.10.3",
+ "serde",
+ "smallvec",
+ "socket2",
+ "time",
+ "tokio",
+ "tokio-util",
+ "tower-layer",
+ "tracing",
+ "url",
+]
+
 [[package]]
 name = "postcard"
 version = "1.1.3"
@@ -4138,6 +4226,7 @@ dependencies = [
  "thiserror 2.0.20",
  "tld",
  "tokio",
+ "tokio-stream",
  "tracing",
  "tracing-subscriber",
  "tsunagi",
@@ -4876,6 +4965,21 @@ dependencies = [
  "time",
 ]
 
+[[package]]
+name = "xml-rs"
+version = "0.8.29"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "e450f9b2ed1dff33c94c12589a87338689467b9c4f5d8a5710bd09a847d2c8a7"
+
+[[package]]
+name = "xmltree"
+version = "0.10.3"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "d7d8a75eaf6557bb84a65ace8609883db44a29951042ada9b393151532e41fcb"
+dependencies = [
+ "xml-rs",
+]
+
 [[package]]
 name = "yasna"
 version = "0.6.0"

Cargo.toml

@@ -27,7 +27,7 @@ expect_used = "warn"
 panic = "warn"
 
 [workspace.dependencies]
-iroh = { version = "1.2", default-features = false, features = ["tls-ring"] }
+iroh = { version = "1.2", default-features = false, features = ["tls-ring", "portmapper"] }
 tokio = { version = "1.53", features = ["rt", "rt-multi-thread", "sync", "time", "macros"] }
 serde = { version = "1.0", features = ["derive"] }
 postcard = { version = "1.1", default-features = false, features = ["use-std"] }

crates/tsunagi-cli/src/main.rs

@@ -33,13 +33,10 @@ use tsunagi_wg_quic::{WireguardConfig, WireguardPlugin};
 #[command(name = "tsunagi", version, about, long_about = None)]
 struct Cli {
     /// Log filter, for example `info` or `tsunagi=debug`.
-    #[arg(
+    ///
-        long,
+    /// Can also be set via the `TSUNAGI_LOG` or `RUST_LOG` environment variables.
-        global = true,
+    #[arg(long, global = true)]
-        env = "TSUNAGI_LOG",
+    log: Option<String>,
-        default_value = "info,iroh=warn,quinn=warn,rustls=warn,boringtun=warn,mainline=off"
-    )]
-    log: String,
 
     #[command(subcommand)]
     command: Command,
@@ -696,9 +693,19 @@ fn parse_peer(text: &str) -> Result<EndpointAddr, String> {
 fn main() -> std::process::ExitCode {
     let cli = Cli::parse();
 
+    let log_filter = cli
+        .log
+        .or_else(|| std::env::var("TSUNAGI_LOG").ok())
+        .or_else(|| std::env::var("RUST_LOG").ok())
+        .unwrap_or_else(|| {
+            "info,iroh=warn,quinn=warn,rustls=warn,boringtun=warn,mainline=off".to_string()
+        });
+
+    let is_debug = log_filter.contains("debug") || log_filter.contains("trace");
+
     tracing_subscriber::fmt()
-        .with_env_filter(tracing_subscriber::EnvFilter::new(&cli.log))
+        .with_env_filter(tracing_subscriber::EnvFilter::new(&log_filter))
-        .with_target(false)
+        .with_target(is_debug)
         .compact()
         .with_writer(std::io::stderr)
         .init();

crates/tsunagi/Cargo.toml

@@ -38,6 +38,7 @@ iroh.workspace = true
 # `net` for the local control interface: a Unix socket on Unix, a named pipe
 # on Windows. Both live behind the same `net` feature.
 tokio = { workspace = true, features = ["net"] }
+tokio-stream = "0.1"
 serde.workspace = true
 postcard.workspace = true
 bytes.workspace = true

crates/tsunagi/src/agent/session.rs

@@ -80,11 +80,12 @@ pub(crate) struct Session {
     pub(crate) bytes_received: u64,
     reader: JoinHandle<()>,
     writer: JoinHandle<()>,
+    path_monitor: JoinHandle<()>,
     shutdown: Shutdown,
 }
 
 impl Session {
-    /// Signals both tasks to stop and waits for them, with a bounded grace
+    /// Signals all tasks to stop and waits for them, with a bounded grace
     /// period.
     ///
     /// A peer that stops reading must not be able to hold up shutdown, so the
@@ -94,6 +95,7 @@ impl Session {
             conn,
             reader,
             writer,
+            path_monitor,
             shutdown,
             ..
         } = self;
@@ -103,23 +105,27 @@ impl Session {
 
         let reader_abort = reader.abort_handle();
         let writer_abort = writer.abort_handle();
+        let path_abort = path_monitor.abort_handle();
         let joined = tokio::time::timeout(STOP_GRACE, async move {
             let _ = reader.await;
             let _ = writer.await;
+            let _ = path_monitor.await;
         })
         .await;
         if joined.is_err() {
             tracing::debug!("session tasks did not wind down in time; aborting them");
             reader_abort.abort();
             writer_abort.abort();
+            path_abort.abort();
         }
     }
 
-    /// Aborts both tasks without waiting. Used on replacement.
+    /// Aborts all tasks without waiting. Used on replacement.
     pub(crate) fn abort(&self) {
         self.shutdown.trigger();
         self.reader.abort();
         self.writer.abort();
+        self.path_monitor.abort();
     }
 }
 
@@ -155,6 +161,52 @@ pub(crate) fn spawn(
         parent_shutdown.clone(),
     ));
 
+    let path_conn = conn.clone();
+    let path_shutdown = shutdown.clone();
+    let path_parent = parent_shutdown.clone();
+    let path_monitor = tokio::spawn(async move {
+        use tokio_stream::StreamExt;
+        let mut events = path_conn.path_events();
+        loop {
+            tokio::select! {
+                biased;
+                _ = path_shutdown.wait() => break,
+                _ = path_parent.wait() => break,
+                ev = events.next() => {
+                    match ev {
+                        Some(iroh::endpoint::PathEvent::Selected { remote_addr, local_addr, .. }) => {
+                            tracing::debug!(
+                                peer = %peer.fmt_short(),
+                                remote = %remote_addr,
+                                local = ?local_addr,
+                                "Connection path selected (direct / relay / hole punch switch)"
+                            );
+                        }
+                        Some(iroh::endpoint::PathEvent::Opened { remote_addr, .. }) => {
+                            tracing::debug!(
+                                peer = %peer.fmt_short(),
+                                remote = %remote_addr,
+                                "Network path opened to peer"
+                            );
+                        }
+                        Some(iroh::endpoint::PathEvent::Closed { remote_addr, .. }) => {
+                            tracing::debug!(
+                                peer = %peer.fmt_short(),
+                                remote = %remote_addr,
+                                "Network path closed for peer"
+                            );
+                        }
+                        Some(iroh::endpoint::PathEvent::Lagged { missed, .. }) => {
+                            tracing::trace!(peer = %peer.fmt_short(), missed, "Path events lagged");
+                        }
+                        Some(_) => {}
+                        None => break,
+                    }
+                }
+            }
+        }
+    });
+
     let reader = tokio::spawn(reader_task(
         id,
         network_id,
@@ -182,6 +234,7 @@ pub(crate) fn spawn(
         bytes_received: 0,
         reader,
         writer,
+        path_monitor,
         shutdown,
     }
 }

crates/tsunagi/src/net.rs

@@ -259,6 +259,91 @@ impl EndpointAdapter {
             .await
             .map_err(|err| Error::Endpoint(format!("cannot bind endpoint: {err}")))?;
 
+        tracing::debug!(
+            endpoint = %endpoint.id().fmt_short(),
+            bound_sockets = ?endpoint.bound_sockets(),
+            "iroh endpoint bound locally"
+        );
+
+        let ep_id = endpoint.id();
+        let mut addr_watcher = endpoint.watch_addr();
+        let mut relay_watcher = endpoint.home_relay_status();
+        let close_token = endpoint.clone();
+        tokio::spawn(async move {
+            use iroh::Watcher;
+            let mut last_addrs: Vec<SocketAddr> = Vec::new();
+            let mut last_relays: Vec<String> = Vec::new();
+
+            let warn_timer = tokio::time::sleep(Duration::from_secs(12));
+            tokio::pin!(warn_timer);
+            let mut warned = false;
+
+            loop {
+                tokio::select! {
+                    biased;
+                    _ = close_token.closed() => {
+                        break;
+                    }
+                    () = &mut warn_timer, if !warned => {
+                        warned = true;
+                        if last_addrs.is_empty() && !last_relays.is_empty() {
+                            tracing::warn!(
+                                endpoint = %ep_id.fmt_short(),
+                                relays = ?last_relays,
+                                "No direct reflexive or UPnP addresses discovered after probe; communications will rely on relay servers"
+                            );
+                        } else if last_addrs.is_empty() && last_relays.is_empty() {
+                            tracing::warn!(
+                                endpoint = %ep_id.fmt_short(),
+                                "No reachability discovered (neither direct reflexive/UPnP addresses nor relay servers available)"
+                            );
+                        }
+                    }
+                    res = addr_watcher.updated() => {
+                        let addr = match res {
+                            Ok(a) => a,
+                            Err(_) => break,
+                        };
+                        let addrs: Vec<SocketAddr> = addr.ip_addrs().copied().collect();
+                        let relays: Vec<String> = addr.relay_urls().map(|u| u.to_string()).collect();
+
+                        if addrs != last_addrs || relays != last_relays {
+                            tracing::debug!(
+                                endpoint = %ep_id.fmt_short(),
+                                direct_addrs = ?addrs,
+                                relays = ?relays,
+                                "Discovered endpoint reachability (STUN/UPnP/local/relay)"
+                            );
+                            last_addrs = addrs;
+                            last_relays = relays;
+                        }
+                    }
+                    res = relay_watcher.updated() => {
+                        let relays = match res {
+                            Ok(r) => r,
+                            Err(_) => break,
+                        };
+                        for relay in &relays {
+                            if relay.is_connected() {
+                                tracing::debug!(
+                                    endpoint = %ep_id.fmt_short(),
+                                    relay = %relay.url(),
+                                    "Connected to home relay server"
+                                );
+                            } else if let Some(err) = relay.last_error() {
+                                tracing::debug!(
+                                    endpoint = %ep_id.fmt_short(),
+                                    relay = %relay.url(),
+                                    error = %err,
+                                    "Relay connection attempt failed"
+                                );
+                            }
+                        }
+                    }
+                }
+            }
+        });
+
         Ok(Self { endpoint })
     }