Implement swarm specific error handling

SignalServiceKit/src/Loki/API/LokiAPI+SwarmAPI.swift

@@ -7,7 +7,7 @@ extension LokiAPI {
     private static let defaultSnodePort: UInt16 = 8080
     
     // MARK: Caching
-    private static var swarmCache: [String:[Target]] = [:]
+    fileprivate static var swarmCache: [String:[Target]] = [:] // TODO: Persist on disk
     
     // MARK: Internal API
     private static func getRandomSnode() -> Promise<Target> {
@@ -21,7 +21,7 @@ extension LokiAPI {
             return Promise<[Target]> { $0.fulfill(cachedSwarm) }
         } else {
             let parameters: [String:Any] = [ "pubKey" : hexEncodedPublicKey ]
-            return getRandomSnode().then { invoke(.getSwarm, on: $0, with: parameters) }.map { parseTargets(from: $0) }.get { swarmCache[hexEncodedPublicKey] = $0 }
+            return getRandomSnode().then { invoke(.getSwarm, on: $0, associatedWith: hexEncodedPublicKey, parameters: parameters) }.map { parseTargets(from: $0) }.get { swarmCache[hexEncodedPublicKey] = $0 }
         }
     }
     
@@ -44,3 +44,27 @@ extension LokiAPI {
 //        return addresses.map { Target(address: $0, port: defaultSnodePort) }
     }
 }
+
+internal extension Promise {
+    
+    func handlingSwarmSpecificErrorsIfNeeded(for target: LokiAPI.Target, associatedWith hexEncodedPublicKey: String) -> Promise<T> {
+        return recover { error -> Promise<T> in
+            if let error = error as? NetworkManagerError {
+                switch error.statusCode {
+                case 0:
+                    // The snode is unreachable; usually a problem with LokiNet
+                    Logger.warn("[Loki] There appears to be a problem with LokiNet.")
+                case 421:
+                    // The snode isn't associated with the given public key anymore
+                    let swarm = LokiAPI.swarmCache[hexEncodedPublicKey]
+                    if var swarm = swarm, let index = swarm.firstIndex(of: target) {
+                        swarm.remove(at: index)
+                        LokiAPI.swarmCache[hexEncodedPublicKey] = swarm
+                    }
+                default: break
+                }
+            }
+            throw error
+        }
+    }
+}

SignalServiceKit/src/Loki/API/LokiAPI.swift

@@ -13,9 +13,9 @@ import PromiseKit
         let port: UInt16
         
         enum Method : String {
-            /// Only applicable to snode targets.
+            /// Only supported by snode targets.
             case getSwarm = "get_snodes_for_pubkey"
-            /// Only applicable to snode targets.
+            /// Only supported by snode targets.
             case getMessages = "retrieve"
             case sendMessage = "store"
         }
@@ -38,10 +38,10 @@ import PromiseKit
     override private init() { }
     
     // MARK: Internal API
-    internal static func invoke(_ method: Target.Method, on target: Target, with parameters: [String:Any] = [:]) -> Promise<RawResponse> {
+    internal static func invoke(_ method: Target.Method, on target: Target, associatedWith hexEncodedPublicKey: String, parameters: [String:Any] = [:]) -> Promise<RawResponse> {
         let url = URL(string: "\(target.address):\(target.port)/\(version)/storage_rpc")!
         let request = TSRequest(url: url, method: "POST", parameters: [ "method" : method.rawValue, "params" : parameters ])
-        return TSNetworkManager.shared().makePromise(request: request).map { $0.responseObject }
+        return TSNetworkManager.shared().makePromise(request: request).map { $0.responseObject }.handlingSwarmSpecificErrorsIfNeeded(for: target, associatedWith: hexEncodedPublicKey)
     }
     
     // MARK: Public API
@@ -50,7 +50,7 @@ import PromiseKit
         return getTargetSnodes(for: hexEncodedPublicKey).mapValues { targetSnode in
             let lastHash = getLastMessageHashValue(for: targetSnode) ?? ""
             let parameters: [String:Any] = [ "pubKey" : hexEncodedPublicKey, "lastHash" : lastHash ]
-            return invoke(.getMessages, on: targetSnode, with: parameters).map { rawResponse in
+            return invoke(.getMessages, on: targetSnode, associatedWith: hexEncodedPublicKey, parameters: parameters).map { rawResponse in
                 guard let json = rawResponse as? JSON, let rawMessages = json["messages"] as? [JSON] else { return [] }
                 updateLastMessageHashValueIfPossible(for: targetSnode, from: rawMessages)
                 let newRawMessages = removeDuplicates(from: rawMessages)
@@ -70,7 +70,7 @@ import PromiseKit
             // TODO: Send using P2P protocol
         } else {
             let parameters = lokiMessage.toJSON()
-            return getTargetSnodes(for: lokiMessage.destination).mapValues { invoke(.sendMessage, on: $0, with: parameters).recoverNetworkErrorIfNeeded(on: DispatchQueue.global()) }.map { Set($0) }
+            return getTargetSnodes(for: lokiMessage.destination).mapValues { invoke(.sendMessage, on: $0, associatedWith: lokiMessage.destination, parameters: parameters) }.map { Set($0) }
         }
     }
     
@@ -80,7 +80,7 @@ import PromiseKit
             // TODO: Send using P2P protocol
         } else {
             let parameters: [String:Any] = [ "pubKey" : hexEncodedPublicKey ] // TODO: Figure out correct parameters
-            return getTargetSnodes(for: hexEncodedPublicKey).mapValues { invoke(.sendMessage, on: $0, with: parameters).recoverNetworkErrorIfNeeded(on: DispatchQueue.global()) }.map { Set($0) }
+            return getTargetSnodes(for: hexEncodedPublicKey).mapValues { invoke(.sendMessage, on: $0, associatedWith: hexEncodedPublicKey, parameters: parameters) }.map { Set($0) }
         }
     }
     
@@ -169,16 +169,3 @@ private extension AnyPromise {
         return result
     }
 }
-
-// MARK: Error Handling
-private extension Promise {
-
-    func recoverNetworkErrorIfNeeded(on queue: DispatchQueue) -> Promise<T> {
-        return recover(on: queue) { error -> Promise<T> in
-            switch error {
-            case NetworkManagerError.taskError(_, let underlyingError): throw underlyingError
-            default: throw error
-            }
-        }
-    }
-}