Harden Nostr tag handling

bitchat/Nostr/NostrProtocol.swift

@@ -501,6 +501,10 @@ struct NostrEvent: Codable {
             throw NostrError.invalidEvent
         }
         
+        guard Self.isWithinInboundTagLimits(tags) else {
+            throw NostrError.invalidEvent
+        }
+
         self.id = dict["id"] as? String ?? ""
         self.pubkey = pubkey
         self.created_at = createdAt
@@ -509,6 +513,17 @@ struct NostrEvent: Codable {
         self.content = content
         self.sig = dict["sig"] as? String
     }
+
+    private 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

@@ -963,6 +963,7 @@ private enum ParsedInbound {
     
     init?(_ message: URLSessionWebSocketTask.Message) {
         guard let data = message.data,
+              data.count <= TransportConfig.nostrMaxInboundMessageBytes,
               let array = try? JSONSerialization.jsonObject(with: data) as? [Any],
               array.count >= 2,
               let type = array[0] as? String else {

bitchat/Services/TransportConfig.swift

@@ -129,6 +129,12 @@ enum TransportConfig {
     static let nostrGeohashSampleLimit: Int = 100
     static let nostrDMSubscribeLookbackSeconds: TimeInterval = 86400
 
+    // Nostr inbound event safety limits
+    static let nostrMaxInboundMessageBytes: Int = 256 * 1024
+    static let nostrMaxEventTags: Int = 64
+    static let nostrMaxEventTagValues: Int = 16
+    static let nostrMaxEventTagValueBytes: Int = 1024
+
     // Nostr helpers
     static let nostrShortKeyDisplayLength: Int = 8
     static let nostrConvKeyPrefixLength: Int = 16

bitchat/ViewModels/ChatNostrCoordinator.swift

@@ -262,8 +262,10 @@ final class ChatNostrCoordinator {
         if viewModel.deduplicationService.hasProcessedNostrEvent(event.id) { return }
         viewModel.deduplicationService.recordNostrEvent(event.id)
 
-        let tagSummary = event.tags.map { "[" + $0.joined(separator: ",") + "]" }.joined(separator: ",")
-        SecureLogger.debug("GeoTeleport: recv pub=\(event.pubkey.prefix(8))… tags=\(tagSummary)", category: .session)
+        SecureLogger.debug(
+            "GeoTeleport: recv pub=\(event.pubkey.prefix(8))… tagCount=\(event.tags.count)",
+            category: .session
+        )
 
         if viewModel.identityManager.isNostrBlocked(pubkeyHexLowercased: event.pubkey) {
             return

bitchatTests/NostrProtocolTests.swift

@@ -241,6 +241,51 @@ struct NostrProtocolTests {
         #expect(!signed.isValidSignature())
     }
 
+    @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)
+    }
+
     @Test func geohashNotesSingleFilter_encodesExpectedTagShape() throws {
         let since = Date(timeIntervalSince1970: 1_234_567)
         let filter = NostrFilter.geohashNotes("u4pruyd", since: since, limit: 42)
@@ -254,6 +299,18 @@ struct NostrProtocolTests {
     }
 
     // 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