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>

bitchatTests/AppArchitectureTests.swift

@@ -147,6 +147,44 @@ struct AppArchitectureTests {
         #expect(store.teleportedGeo.isEmpty)
     }
 
+    @Test("LocationPresenceStore bounds and prunes teleported geohash participants")
+    @MainActor
+    func locationPresenceStoreBoundsTeleportedParticipants() {
+        let store = LocationPresenceStore(teleportedGeoCapacity: 2)
+
+        store.setCurrentGeohash("u4pruy")
+        store.markTeleported("AAAAAA")
+        store.markTeleported("BBBBBB")
+        store.markTeleported("CCCCCC")
+
+        #expect(store.teleportedGeo == Set(["bbbbbb", "cccccc"]))
+
+        store.retainTeleportedGeo(keeping: Set(["CCCCCC"]))
+        #expect(store.teleportedGeo == Set(["cccccc"]))
+
+        store.setCurrentGeohash("u4pruz")
+        #expect(store.teleportedGeo.isEmpty)
+    }
+
+    @Test("LocationPresenceStore bounds geohash nicknames and clears on channel switch")
+    @MainActor
+    func locationPresenceStoreBoundsGeoNicknames() {
+        let store = LocationPresenceStore(geoNicknameCapacity: 2)
+
+        store.setCurrentGeohash("u4pruy")
+        store.setNickname("alice", for: "AAAAAA")
+        store.setNickname("bob", for: "BBBBBB")
+        store.setNickname("carol", for: "CCCCCC")
+
+        #expect(store.geoNicknames == ["bbbbbb": "bob", "cccccc": "carol"])
+
+        store.retainGeoNicknames(keeping: Set(["CCCCCC"]))
+        #expect(store.geoNicknames == ["cccccc": "carol"])
+
+        store.setCurrentGeohash("u4pruz")
+        #expect(store.geoNicknames.isEmpty)
+    }
+
     @Test("PeerHandle equality and hashing use the canonical identity only")
     func peerHandleEqualityUsesCanonicalIdentity() {
         let first = PeerHandle(id: "noise:abc123", routingPeerID: PeerID(str: "peer-a"))

bitchatTests/ChatViewModelTests.swift

@@ -646,6 +646,25 @@ struct ChatViewModelFormattingTests {
         #expect(String(formatted.characters) == "<@Alice#a1b2> hello #mesh [\(message.formattedTimestamp)]")
     }
 
+    @Test @MainActor
+    func formatMessageAsText_longCashuFallsBackToPlain() async {
+        let (viewModel, _) = makeTestableViewModel()
+        let cashu = "cashuA" + String(repeating: "a", count: 40)
+        let longContent = "hi @bob " + cashu + " " + String(repeating: "x", count: 4_100)
+        let message = BitchatMessage(
+            id: "fmt-long-cashu",
+            sender: "Alice#a1b2",
+            content: longContent,
+            timestamp: Date(timeIntervalSince1970: 1_700_010_123),
+            isRelay: false,
+            senderPeerID: PeerID(str: "00000000000000b3")
+        )
+
+        let formatted = viewModel.formatMessageAsText(message, colorScheme: .light)
+
+        #expect(String(formatted.characters) == "<@Alice#a1b2> \(longContent) [\(message.formattedTimestamp)]")
+    }
+
     @Test @MainActor
     func formatMessageHeader_formatsSenderHeader() async {
         let (viewModel, _) = makeTestableViewModel()

bitchatTests/MessageFormattingEngineTests.swift

@@ -323,6 +323,32 @@ struct MessageFormattingEngineTests {
         // Exactly at threshold DOES trigger (uses >= comparison)
         #expect(content.hasVeryLongToken(threshold: 50))
     }
+
+    @Test func isLongForDisplay_doesNotIgnoreCashuLinks() {
+        let cashu = "cashuA" + String(repeating: "a", count: 40)
+        let content = String(repeating: "a", count: TransportConfig.uiLongMessageLengthThreshold + 1) + " " + cashu
+
+        #expect(content.extractCashuLinks().count == 1)
+        #expect(content.isLongForDisplay())
+    }
+
+    @MainActor
+    @Test func formatMessage_longCashuMessageFallsBackToPlainContentPath() {
+        let context = MockMessageFormattingContext(nickname: "carol")
+        let cashu = "cashuA" + String(repeating: "a", count: 40)
+        let longContent = "hi @bob " + cashu + " " + String(repeating: "x", count: 4_100)
+        let message = BitchatMessage(
+            id: "long-cashu",
+            sender: "alice",
+            content: longContent,
+            timestamp: Date(timeIntervalSince1970: 1_700_000_999),
+            isRelay: false
+        )
+
+        let formatted = MessageFormattingEngine.formatMessage(message, context: context, colorScheme: .light)
+
+        #expect(String(formatted.characters) == "<@alice> \(longContent) [\(message.formattedTimestamp)]")
+    }
 }
 
 @MainActor

bitchatTests/MessageRateLimiterTests.swift

@@ -116,4 +116,87 @@ struct MessageRateLimiterTests {
         #expect(plain)
         #expect(!plainExhausted)
     }
+
+    @Test("Content buckets do not grow when sender is rate limited")
+    func contentBucketsDoNotGrowAfterSenderLimit() {
+        var limiter = MessageRateLimiter(
+            senderCapacity: 1,
+            senderRefillPerSec: 0,
+            contentCapacity: 1,
+            contentRefillPerSec: 0,
+            maxSenderBuckets: 10,
+            maxContentBuckets: 10,
+            bucketIdleTTL: 60
+        )
+        let now = Date()
+
+        let first = limiter.allow(senderKey: "sender", contentKey: "content-0", now: now)
+        var rejected = true
+        for index in 1...100 {
+            if limiter.allow(senderKey: "sender", contentKey: "content-\(index)", now: now) {
+                rejected = false
+            }
+        }
+
+        #expect(first)
+        #expect(rejected)
+        #expect(limiter.bucketCountsForTesting.sender == 1)
+        #expect(limiter.bucketCountsForTesting.content == 1)
+    }
+
+    @Test("Bucket maps evict entries at configured caps")
+    func bucketMapsEvictAtConfiguredCaps() {
+        let maxEntries = 3
+        var limiter = MessageRateLimiter(
+            senderCapacity: 1,
+            senderRefillPerSec: 0,
+            contentCapacity: 1,
+            contentRefillPerSec: 0,
+            maxSenderBuckets: maxEntries,
+            maxContentBuckets: maxEntries,
+            bucketIdleTTL: 60
+        )
+        let now = Date()
+
+        for index in 0..<25 {
+            _ = limiter.allow(
+                senderKey: "sender-\(index)",
+                contentKey: "content-\(index)",
+                now: now.addingTimeInterval(TimeInterval(index))
+            )
+        }
+
+        #expect(limiter.bucketCountsForTesting.sender == maxEntries)
+        #expect(limiter.bucketCountsForTesting.content == maxEntries)
+    }
+
+    @Test("PoW bypass still creates content buckets under the cap")
+    func powBypassCreatesBoundedContentBuckets() {
+        let maxEntries = 3
+        var limiter = MessageRateLimiter(
+            senderCapacity: 1,
+            senderRefillPerSec: 0,
+            contentCapacity: 100,
+            contentRefillPerSec: 0,
+            maxSenderBuckets: maxEntries,
+            maxContentBuckets: maxEntries,
+            bucketIdleTTL: 60
+        )
+        let now = Date()
+
+        var allAllowed = true
+        for index in 0..<10 {
+            let allowed = limiter.allow(
+                senderKey: "sender",
+                contentKey: "content-\(index)",
+                powBits: NostrPoW.rateLimitBypassBits,
+                now: now.addingTimeInterval(TimeInterval(index))
+            )
+            if !allowed { allAllowed = false }
+        }
+
+        #expect(allAllowed)
+        #expect(limiter.bucketCountsForTesting.sender == 0)
+        #expect(limiter.bucketCountsForTesting.content == maxEntries)
+    }
 }

bitchatTests/NostrProtocolTests.swift

@@ -290,7 +290,65 @@ struct NostrProtocolTests {
         #expect(object["limit"] as? Int == 42)
     }
 
+
+    @Test func inboundNostrEventRejectsTooManyTags() throws {
+        var eventDict = Self.validInboundEventDict()
+        eventDict["tags"] = Array(
+            repeating: ["g", "u4pruyd"],
+            count: TransportConfig.nostrMaxEventTags + 1
+        )
+
+        #expect(throws: NostrError.invalidEvent) {
+            _ = try NostrEvent(from: eventDict)
+        }
+    }
+
+    @Test func inboundNostrEventRejectsTooManyTagValues() throws {
+        var eventDict = Self.validInboundEventDict()
+        eventDict["tags"] = [Array(
+            repeating: "value",
+            count: TransportConfig.nostrMaxEventTagValues + 1
+        )]
+
+        #expect(throws: NostrError.invalidEvent) {
+            _ = try NostrEvent(from: eventDict)
+        }
+    }
+
+    @Test func inboundNostrEventRejectsOversizedTagValues() throws {
+        var eventDict = Self.validInboundEventDict()
+        eventDict["tags"] = [[
+            "g",
+            String(repeating: "a", count: TransportConfig.nostrMaxEventTagValueBytes + 1)
+        ]]
+
+        #expect(throws: NostrError.invalidEvent) {
+            _ = try NostrEvent(from: eventDict)
+        }
+    }
+
+    @Test func inboundNostrEventAcceptsTagsWithinLimits() throws {
+        var eventDict = Self.validInboundEventDict()
+        eventDict["tags"] = [["g", "u4pruyd"], ["t", "teleport"]]
+
+        let event = try NostrEvent(from: eventDict)
+
+        #expect(event.tags.count == 2)
+    }
+
     // MARK: - Helpers
+    private static func validInboundEventDict() -> [String: Any] {
+        [
+            "id": String(repeating: "0", count: 64),
+            "pubkey": String(repeating: "1", count: 64),
+            "created_at": 1_234_567,
+            "kind": NostrProtocol.EventKind.ephemeralEvent.rawValue,
+            "tags": [["g", "u4pruyd"]],
+            "content": "hello",
+            "sig": String(repeating: "2", count: 128)
+        ]
+    }
+
     private static func base64URLDecode(_ s: String) -> Data? {
         var str = s.replacingOccurrences(of: "-", with: "+").replacingOccurrences(of: "_", with: "/")
         let rem = str.count % 4