recording: reject a zero-length window

2 files changed, 16 insertions, 2 deletions

diff --git a/src/config.rs b/src/config.rs
index 95c1a18..e55226c 100644
--- a/src/config.rs
+++ b/src/config.rs
@@ -205,8 +205,11 @@ impl Config {
                 .parse()
                 .unwrap_or(true),
             recording_window_seconds: env::var("RECORDING_WINDOW_SECONDS")
-                .unwrap_or_else(|_| "900".into())
-                .parse()
+                .ok()
+                .and_then(|value| value.parse::<u64>().ok())
+                // 0 would divide by zero in the mixer; cap the ring so a typo
+                // cannot allocate an unbounded amount of memory.
+                .filter(|seconds| (1..=3600).contains(seconds))
                 .unwrap_or(900),
             copyparty_url: env::var("COPYPARTY_URL")
                 .unwrap_or_else(|_| "http://localhost:3939".into()),
diff --git a/src/recording/mod.rs b/src/recording/mod.rs
index 4cd2891..e03df32 100644
--- a/src/recording/mod.rs
+++ b/src/recording/mod.rs
@@ -57,6 +57,9 @@ struct Inner {
 impl Recorder {
     pub fn new(sample_rate: u32, window_seconds: u64) -> Self {
         let samples_per_frame = (sample_rate as usize) / TICKS_PER_SEC;
+        // Defensive: callers validate config, but a zero-length ring would
+        // panic on `% len` in `mix_tick`.
+        let window_seconds = window_seconds.max(1);
         let window_samples = (sample_rate as usize) * (window_seconds as usize);
         // `head` advances by `samples_per_frame` and wraps mod `window_samples`,
         // so the window length must be a whole number of frames.
@@ -342,6 +345,14 @@ mod tests {
     }
 
     #[test]
+    fn zero_window_is_clamped_and_does_not_panic() {
+        let rec = Recorder::new(48_000, 0);
+        let spf = rec.samples_per_frame;
+        rec.mix_tick(&[vec![1i16; spf]]);
+        assert!(!rec.flush().is_empty());
+    }
+
+    #[test]
     fn single_speaker_values_survive() {
         let rec = Recorder::new(48_000, 1);
         let spf = rec.samples_per_frame;