From 13576e75d90ae275bc8c36bc1de19a8d4ab48eff Mon Sep 17 00:00:00 2001
From: Nathan Perry <nathan@tailscale.com>
Date: Fri, 14 Aug 2026 12:11:42 -0400
Subject: [PATCH] runtime/control: populate initial maprequest

The initial maprequest wasn't populated with the info held by the
control actor in a way consistent with future update_map_request calls.
This didn't cause an issue because the derp latency map measurement
always triggers an update_map_request (assuming it succeeds), but this
was essentially a latent bug.

Signed-off-by: Nathan Perry <nathan@tailscale.com>
Change-Id: I83128caa6936b6f92abf301f0fe5acca6a6a6964
---
 ts_control/src/client/mod.rs     |  5 +++
 ts_control/src/lib.rs            |  2 +-
 ts_runtime/src/control_runner.rs | 68 +++++++++++++++++++++-----------
 3 files changed, 52 insertions(+), 23 deletions(-)

diff --git a/ts_control/src/client/mod.rs b/ts_control/src/client/mod.rs
index d67b6911..ca1d5e9e 100644
--- a/ts_control/src/client/mod.rs
+++ b/ts_control/src/client/mod.rs
@@ -23,6 +23,11 @@ pub use register::{RegistrationError, register};
 pub type HttpConn = Http2<BytesBody>;
 
 /// Start the netmap stream. This connection should already be registered successfully.
+///
+/// This is a convenience helper for callers without a strong opinion on the information
+/// included in their initial map request: sophisticated callers that have hostinfo/netinfo or other
+/// fields to populate should manually [`send_map_request`] with their desired request and
+/// [`map_stream`] on the result.
 pub async fn start_stream(
     control_url: &Url,
     node_keys: &ts_keys::NodeState,
diff --git a/ts_control/src/lib.rs b/ts_control/src/lib.rs
index c5b0f5d5..cd4f5e61 100644
--- a/ts_control/src/lib.rs
+++ b/ts_control/src/lib.rs
@@ -32,7 +32,7 @@ pub use node::{
     Id as NodeId, Node, NodeLastSeen, NodeStatus, NodeUpdate, StableId as StableNodeId,
     TailnetAddress,
 };
-pub use ts_control_serde::{Endpoint, EndpointType};
+pub use ts_control_serde::{Endpoint, EndpointType, MapRequest};
 
 /// An error which occurred while connecting to the control server or control plane.
 #[derive(Debug, thiserror::Error, Clone, Eq, PartialEq)]
diff --git a/ts_runtime/src/control_runner.rs b/ts_runtime/src/control_runner.rs
index 7e84499b..946265b7 100644
--- a/ts_runtime/src/control_runner.rs
+++ b/ts_runtime/src/control_runner.rs
@@ -11,7 +11,7 @@ use kameo::{
 };
 use ts_control::{
     ControlDialer, DialPlan, Endpoint, Error as ControlError, Node, RegistrationError, StateUpdate,
-    client::{HttpConn, handle_ping, send_map_request},
+    client::{HttpConn, handle_ping, map_stream, send_map_request},
 };
 
 use crate::{
@@ -248,15 +248,26 @@ impl ControlRunner {
 }
 
 impl ControlRunner {
-    async fn update_map_request(&self) {
-        let RegState::Registered(conn) = &self.state else {
-            tracing::debug!("attempt to update map request while not registered");
-            return;
+    /// Call `f` with a map request built from the current control actor state.
+    ///
+    /// `stream` dictates whether the request is built for a streaming netmap response or as a
+    /// request to update to this node's fields in control.
+    ///
+    /// This takes a closure rather than returning the built request for lifetime reasons.
+    async fn with_map_request<T>(
+        &self,
+        stream: bool,
+        f: impl AsyncFnOnce(ts_control::MapRequest) -> T,
+    ) -> T {
+        let mut mrb = ts_control::MapRequestBuilder::new(&self.params.env.keys);
+
+        mrb = if stream {
+            mrb.as_stream()
+        } else {
+            mrb.as_request()
         };
 
-        let mut mrb = ts_control::MapRequestBuilder::new(&self.params.env.keys)
-            .as_request()
-            .endpoints(self.endpoints.clone());
+        mrb = mrb.endpoints(self.endpoints.clone());
 
         if let Some(hostname) = self.params.config.hostname.as_deref() {
             mrb = mrb.hostname(hostname);
@@ -284,11 +295,23 @@ impl ControlRunner {
         host_info.app = &client_name;
         host_info.ipn_version = ts_control::PKG_VERSION;
 
-        send_map_request(
-            request,
-            &self.params.config.server_url.join("machine/map").unwrap(),
-            conn,
-        )
+        f(request).await
+    }
+
+    async fn update_map_request(&self) {
+        let RegState::Registered(conn) = &self.state else {
+            tracing::debug!("attempt to update map request while not registered");
+            return;
+        };
+
+        self.with_map_request(false, async |req| {
+            send_map_request(
+                req,
+                &self.params.config.server_url.join("machine/map").unwrap(),
+                conn,
+            )
+            .await
+        })
         .await
         .unwrap();
     }
@@ -346,15 +369,16 @@ impl Message<RegisterResult> for ControlRunner {
             }
         }
 
-        let stream = ts_control::client::start_stream(
-            &self.params.config.server_url,
-            &self.params.env.keys,
-            &self.params.config,
-            conn,
-        )
-        .await
-        .unwrap()
-        .map(Arc::new);
+        let reader = self
+            .with_map_request(true, async |req| {
+                let map_url = self.params.config.server_url.join("machine/map").unwrap();
+
+                send_map_request(req, &map_url, &conn).await
+            })
+            .await
+            .unwrap();
+
+        let stream = map_stream(reader).map(Arc::new);
 
         ctx.actor_ref().attach_stream(stream.boxed(), (), ());
     }