Add DNS SRV bootstrap discovery for automatic peer finding

tpd now queries _tesseras._udp.tesseras.net SRV records to discover
bootstrap peers when no -b flag is given. Add -n flag to disable this
automatic discovery for seed/isolated nodes.

1 files changed, 22 insertions, 4 deletions

diff --git a/src/bin/tpd.rs b/src/bin/tpd.rs
index 15e7d9b..2b7fdb2 100644
--- a/src/bin/tpd.rs
+++ b/src/bin/tpd.rs
@@ -10,6 +10,8 @@ mod base58;
 mod crypto;
 #[path = "../daemon.rs"]
 mod daemon;
+#[path = "../dns.rs"]
+mod dns;
 #[path = "../ops.rs"]
 mod ops;
 #[path = "../paste.rs"]
@@ -35,7 +37,7 @@ fn default_dir() -> PathBuf {
 fn usage() {
     eprintln!(
         "usage: tpd [-p port] [-d dir] [-s sock] \
-         [-w http_port] [-g] [-b host:port] [-h]"
+         [-w http_port] [-g] [-n] [-b host:port] [-h]"
     );
     eprintln!();
     eprintln!("  -p port       UDP port (0 = random)");
@@ -43,6 +45,7 @@ fn usage() {
     eprintln!("  -s sock       Unix socket path");
     eprintln!("  -w port       HTTP server port");
     eprintln!("  -g            global NAT (public server)");
+    eprintln!("  -n            no auto-bootstrap (skip DNS SRV)");
     eprintln!("  -b host:port  bootstrap peer (repeatable)");
     eprintln!("  -h            show this help");
 }
@@ -62,6 +65,7 @@ fn main() {
     let mut sock: Option<PathBuf> = None;
     let mut http_port: Option<u16> = None;
     let mut global = false;
+    let mut no_auto_bootstrap = false;
     let mut bootstrap: Vec<String> = Vec::new();
 
     let args: Vec<String> = std::env::args().collect();
@@ -104,6 +108,7 @@ fn main() {
                 );
             }
             "-g" => global = true,
+            "-n" => no_auto_bootstrap = true,
             "-b" => {
                 i += 1;
                 if let Some(addr) = args.get(i) {
@@ -181,22 +186,35 @@ fn main() {
     let id = node.id_hex();
     eprintln!("tpd {addr} id={:.8}", id);
 
+    // If no explicit peers given and auto-bootstrap is enabled,
+    // discover peers via DNS SRV (_tesseras._udp.tesseras.net).
+    if bootstrap.is_empty() && !no_auto_bootstrap {
+        log::info!("bootstrap: resolving SRV records");
+        let srv = dns::lookup_bootstrap();
+        if srv.is_empty() {
+            log::warn!("bootstrap: no SRV records found");
+        }
+        for rec in &srv {
+            bootstrap.push(format!("{}:{}", rec.host, rec.port));
+        }
+    }
+
     for peer in &bootstrap {
         let parts: Vec<&str> = peer.rsplitn(2, ':').collect();
         if parts.len() != 2 {
-            eprintln!("warning: bad bootstrap: {peer}");
+            eprintln!("warning: bad bootstrap address: {peer}");
             continue;
         }
         let host = parts[1];
         let p: u16 = match parts[0].parse() {
             Ok(p) => p,
             Err(_) => {
-                eprintln!("warning: bad port: {peer}");
+                eprintln!("warning: bad bootstrap port: {peer}");
                 continue;
             }
         };
         if let Err(e) = node.join(host, p) {
-            eprintln!("warning: bootstrap {peer}: {e}");
+            log::warn!("bootstrap: failed to join {peer}: {e}");
         } else {
             log::info!("bootstrap: connected to {peer}");
         }