Harden public intake bounds against untrusted growth (#1451)

* Bound public rate-limit buckets against attacker-keyed growth.

Keep the NIP-13 PoW sender bypass, skip content-bucket minting on
sender reject, and evict idle/oldest entries at a hard cap.

Co-authored-by: Cursor <cursoragent@cursor.com>

* Stop Cashu-looking text from skipping long-message guards.

Oversized public content always collapses and takes the plain
formatting path so remote tokens cannot force layout/regex DoS.

Co-authored-by: Cursor <cursoragent@cursor.com>

* Cap teleported geohash participant markers.

Bound the set with FIFO eviction, clear it on channel switch, and
prune markers that leave the visible participant list.

Co-authored-by: Cursor <cursoragent@cursor.com>

* Bound untrusted Nostr relay frames and event tags.

Reject oversized inbound messages before JSON parse, cap tag
arrays/values at decode, and stop logging raw tag contents.

Co-authored-by: Cursor <cursoragent@cursor.com>

* Fail soft when Noise handshake state is unexpectedly missing.

Replace the initiator startHandshake force unwrap with a guard
that throws invalidState instead of crashing.

Co-authored-by: Cursor <cursoragent@cursor.com>

* Cap geohash nickname cache from remote Nostr events.

FIFO-evict at capacity, clear on channel switch, and prune
nicknames that leave the visible participant list.

Co-authored-by: Cursor <cursoragent@cursor.com>

* Avoid overlapping exclusive access in the rate limiter.

Make bucket helpers static so inout dictionary updates do not
conflict with a mutating call on self.

Co-authored-by: Cursor <cursoragent@cursor.com>

* Fix rate-limiter tests for mutating allow under #expect.

Call allow outside the macro so Swift Testing does not capture an
immutable copy of the struct.

Co-authored-by: Cursor <cursoragent@cursor.com>

* Drop unused WebSocket data helper; reset rate limiter on panic wipe.

dataWithinInboundLimit replaced the unbounded path, and panic clear
should not leave public intake buckets behind.

Co-authored-by: Cursor <cursoragent@cursor.com>

---------

Co-authored-by: Cursor <cursoragent@cursor.com>

bitchat/Nostr/NostrProtocol.swift

@@ -700,6 +700,10 @@ struct NostrEvent: Codable {
               let content = dict["content"] as? String else {
             throw NostrError.invalidEvent
         }
+
+        guard Self.isWithinInboundTagLimits(tags) else {
+            throw NostrError.invalidEvent
+        }
         
         self.id = dict["id"] as? String ?? ""
         self.pubkey = pubkey
@@ -709,6 +713,21 @@ struct NostrEvent: Codable {
         self.content = content
         self.sig = dict["sig"] as? String
     }
+
+    /// Bounds untrusted relay tag arrays so attackers cannot force large
+    /// allocations or expensive joins on the inbound hot path.
+    static func isWithinInboundTagLimits(_ tags: [[String]]) -> Bool {
+        guard tags.count <= TransportConfig.nostrMaxEventTags else { return false }
+
+        for tag in tags {
+            guard tag.count <= TransportConfig.nostrMaxEventTagValues else { return false }
+            guard tag.allSatisfy({ $0.utf8.count <= TransportConfig.nostrMaxEventTagValueBytes }) else {
+                return false
+            }
+        }
+
+        return true
+    }
     
     func sign(with key: P256K.Schnorr.PrivateKey) throws -> NostrEvent {
         let (eventId, eventIdHash) = try calculateEventId()

bitchat/Nostr/NostrRelayManager.swift

@@ -1480,7 +1480,7 @@ private enum ParsedInbound {
     case notice(String)
     
     init?(_ message: URLSessionWebSocketTask.Message) {
-        guard let data = message.data,
+        guard let data = message.dataWithinInboundLimit,
               let array = try? JSONSerialization.jsonObject(with: data) as? [Any],
               array.count >= 2,
               let type = array[0] as? String else {
@@ -1525,11 +1525,19 @@ private enum ParsedInbound {
 }
 
 private extension URLSessionWebSocketTask.Message {
-    var data: Data? {
+    /// Prefer rejecting oversized frames before UTF-8/Data materialization
+    /// where we can (string length), and always before JSON parse.
+    var dataWithinInboundLimit: Data? {
+        let maxBytes = TransportConfig.nostrMaxInboundMessageBytes
         switch self {
-        case .string(let text): text.data(using: .utf8)
-        case .data(let data):   data
-        @unknown default:       nil
+        case .string(let text):
+            guard text.utf8.count <= maxBytes else { return nil }
+            return text.data(using: .utf8)
+        case .data(let data):
+            guard data.count <= maxBytes else { return nil }
+            return data
+        @unknown default:
+            return nil
         }
     }
 }