Struct RotatingNonceCache 

pub struct RotatingNonceCache { /* private fields */ }

Two-bucket rotating nonce cache for WS-Security replay detection.

Buckets rotate every half_window seconds (default: 150 s → 300 s total window). A nonce present in either bucket is considered a replay and rejected.

When the current bucket reaches max_entries a forced rotation occurs so the bucket is replaced by an empty one — legitimate traffic continues but further nonces from the previous bucket will no longer be detected as replays. This is preferable to unbounded growth; the trade-off is documented in check_and_insert.

Thread-safety

check_and_insert takes &mut self, so RotatingNonceCache itself is not thread-safe. Wrap it in a tokio::sync::Mutex (or std::sync::Mutex for sync contexts) before sharing across async tasks:

use tokio::sync::Mutex;
use soap_server::RotatingNonceCache;

let cache = Arc::new(Mutex::new(RotatingNonceCache::new(150)));
// Inside an async handler:
let mut cache = cache.lock().await;
cache.check_and_insert(&nonce)?;

The soap-server SoapService handles this internally — consumers using validate_username_token via the server builder do not need to manage the cache directly. Consider interior-mutability refactoring in v0.2.

Implementations

impl RotatingNonceCache

pub fn new(half_window_secs: u64) -> Self

Create a new cache with the given time-window and default entry cap (100 000).

pub fn with_max_entries(half_window_secs: u64, max_entries: usize) -> Self

Create a new cache with explicit time-window and per-bucket entry cap.

pub fn check_and_insert(&mut self, nonce: &str) -> Result<(), SoapFault>

Check nonce for replay and insert if not seen. Returns Err on replay.

If the current bucket is at capacity (max_entries), a forced rotation is performed before inserting: the current bucket becomes the previous bucket and a fresh empty bucket is started. This bounds memory use at the cost of a narrow window where very recently-rotated nonces are no longer tracked — a DoS flood that exhausts the cap is still bounded, and normal traffic is not disrupted.