1 files changed, 91 insertions, 0 deletions
diff --git a/rust/src/rendezvous/session.rs b/rust/src/rendezvous/session.rs
new file mode 100644
index 0000000000..179304edfe
--- /dev/null
+++ b/rust/src/rendezvous/session.rs
@@ -0,0 +1,91 @@
+/*
+ * This file is licensed under the Affero General Public License (AGPL) version 3.
+ *
+ * Copyright (C) 2024 New Vector, Ltd
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as
+ * published by the Free Software Foundation, either version 3 of the
+ * License, or (at your option) any later version.
+ *
+ * See the GNU Affero General Public License for more details:
+ * <https://www.gnu.org/licenses/agpl-3.0.html>.
+ */
+
+use std::time::{Duration, SystemTime};
+
+use base64::{engine::general_purpose::URL_SAFE_NO_PAD, Engine as _};
+use bytes::Bytes;
+use headers::{ContentLength, ContentType, ETag, Expires, LastModified};
+use mime::Mime;
+use sha2::{Digest, Sha256};
+
+/// A single session, containing data, metadata, and expiry information.
+pub struct Session {
+    hash: [u8; 32],
+    data: Bytes,
+    content_type: Mime,
+    last_modified: SystemTime,
+    expires: SystemTime,
+}
+
+impl Session {
+    /// Create a new session with the given data, content type, and time-to-live.
+    pub fn new(data: Bytes, content_type: Mime, now: SystemTime, ttl: Duration) -> Self {
+        let hash = Sha256::digest(&data).into();
+        Self {
+            hash,
+            data,
+            content_type,
+            expires: now + ttl,
+            last_modified: now,
+        }
+    }
+
+    /// Returns true if the session has expired at the given time.
+    pub fn expired(&self, now: SystemTime) -> bool {
+        self.expires <= now
+    }
+
+    /// Update the session with new data, content type, and last modified time.
+    pub fn update(&mut self, data: Bytes, content_type: Mime, now: SystemTime) {
+        self.hash = Sha256::digest(&data).into();
+        self.data = data;
+        self.content_type = content_type;
+        self.last_modified = now;
+    }
+
+    /// Returns the Content-Type header of the session.
+    pub fn content_type(&self) -> ContentType {
+        self.content_type.clone().into()
+    }
+
+    /// Returns the Content-Length header of the session.
+    pub fn content_length(&self) -> ContentLength {
+        ContentLength(self.data.len() as _)
+    }
+
+    /// Returns the ETag header of the session.
+    pub fn etag(&self) -> ETag {
+        let encoded = URL_SAFE_NO_PAD.encode(self.hash);
+        // SAFETY: Base64 encoding is URL-safe, so ETag-safe
+        format!("\"{encoded}\"")
+            .parse()
+            .expect("base64-encoded hash should be URL-safe")
+    }
+
+    /// Returns the Last-Modified header of the session.
+    pub fn last_modified(&self) -> LastModified {
+        self.last_modified.into()
+    }
+
+    /// Returns the Expires header of the session.
+    pub fn expires(&self) -> Expires {
+        self.expires.into()
+    }
+
+    /// Returns the current data stored in the session.
+    pub fn data(&self) -> Bytes {
+        self.data.clone()
+    }
+}