fix(server::bootsrapper): token compare is now constant-time

server/Cargo.lock

@@ -760,6 +760,7 @@ dependencies = [
  "smlang",
  "spki",
  "strum 0.28.0",
+ "subtle",
  "test-log",
  "thiserror 2.0.18",
  "tokio",

server/crates/arbiter-server/Cargo.toml

@@ -60,6 +60,7 @@ arbiter-tokens-registry.path = "../arbiter-tokens-registry"
 anyhow = "1.0.102"
 serde_with = "3.18.0"
 mutants.workspace = true
+subtle = "2.6.1"
 
 [dev-dependencies]
 insta = "1.46.3"

server/crates/arbiter-server/src/actors/bootstrap.rs

@@ -4,6 +4,7 @@ use diesel_async::RunQueryDsl;
 use kameo::{Actor, messages};
 
 use rand::{RngExt, distr::Alphanumeric, make_rng, rngs::StdRng};
+use subtle::ConstantTimeEq as _;
 use thiserror::Error;
 
 use crate::db::{self, DatabasePool, schema};
@@ -44,14 +45,14 @@ pub struct Bootstrapper {
 
 impl Bootstrapper {
     pub async fn new(db: &DatabasePool) -> Result<Self, Error> {
-        let mut conn = db.get().await?;
+        let row_count: i64 = {
+            let mut conn = db.get().await?;
 
-        let row_count: i64 = schema::useragent_client::table
-            .count()
-            .get_result(&mut conn)
-            .await?;
-
-        drop(conn);
+            schema::useragent_client::table
+                .count()
+                .get_result(&mut conn)
+                .await?
+        };
 
         let token = if row_count == 0 {
             let token = generate_token().await?;
@@ -69,7 +70,13 @@ impl Bootstrapper {
     #[message]
     pub fn is_correct_token(&self, token: String) -> bool {
         match &self.token {
-            Some(expected) => *expected == token,
+            Some(expected) => {
+                let expected_bytes = expected.as_bytes();
+                let token_bytes = token.as_bytes();
+
+                let choice = expected_bytes.ct_eq(token_bytes);
+                bool::from(choice)
+            }
             None => false,
         }
     }