Use only updated snodes for file server proxying

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

@@ -1,14 +1,14 @@
 import PromiseKit
 
 public extension LokiAPI {
+    private static var snodeVersion: [LokiAPITarget:String] = [:]
 
     /// Only ever accessed from `LokiAPI.errorHandlingQueue` to avoid race conditions.
     fileprivate static var failureCount: [LokiAPITarget:UInt] = [:]
-    
+
     // MARK: Settings
     private static let minimumSnodeCount = 2
     private static let targetSnodeCount = 3
-    private static let maxRandomSnodePoolSize = 1024
     fileprivate static let failureThreshold = 2
     
     // MARK: Caching
@@ -84,11 +84,44 @@ public extension LokiAPI {
         }
     }
 
-    // MARK: Public API
     internal static func getTargetSnodes(for hexEncodedPublicKey: String) -> Promise<[LokiAPITarget]> {
         // shuffled() uses the system's default random generator, which is cryptographically secure
         return getSwarm(for: hexEncodedPublicKey).map { Array($0.shuffled().prefix(targetSnodeCount)) }
     }
+
+    internal static func getFileServerProxy() -> Promise<LokiAPITarget> {
+        let (promise, seal) = Promise<LokiAPITarget>.pending()
+        func getVersion(for snode: LokiAPITarget) -> Promise<String> {
+            let url = URL(string: "\(snode.address):\(snode.port)/get_stats/v1")!
+            let request = TSRequest(url: url)
+            if let version = snodeVersion[snode] {
+                return Promise { $0.fulfill(version) }
+            } else {
+                return TSNetworkManager.shared().perform(request, withCompletionQueue: DispatchQueue.global()).map(on: DispatchQueue.global()) { intermediate in
+                    let rawResponse = intermediate.responseObject
+                    guard let json = rawResponse as? JSON, let version = json["version"] as? String else { throw LokiAPIError.missingSnodeVersion }
+                    snodeVersion[snode] = version
+                    return version
+                }
+            }
+        }
+        getRandomSnode().done(on: DispatchQueue.global()) { snode in
+            getVersion(for: snode).then(on: DispatchQueue.global()) { version -> Promise<LokiAPITarget> in
+                if version >= "2.0.2" {
+                    print("[Loki] Using file server proxy with version number \(version).")
+                    return Promise { $0.fulfill(snode) }
+                } else {
+                    print("[Loki] Rejecting file server proxy with version number \(version).")
+                    return getFileServerProxy()
+                }
+            }.recover(on: DispatchQueue.global()) { error in
+                return getFileServerProxy()
+            }
+        }.catch(on: DispatchQueue.global()) { error in
+            seal.reject(error)
+        }
+        return promise
+    }
     
     // MARK: Parsing
     private static func parseTargets(from rawResponse: Any) -> [LokiAPITarget] {

SignalServiceKit/src/Loki/API/LokiAPI.swift

@@ -47,6 +47,7 @@ public final class LokiAPI : NSObject {
         @objc public static let messageConversionFailed = LokiAPIError(domain: "LokiAPIErrorDomain", code: 2, userInfo: [ NSLocalizedDescriptionKey : "Failed to construct message." ])
         @objc public static let clockOutOfSync = LokiAPIError(domain: "LokiAPIErrorDomain", code: 3, userInfo: [ NSLocalizedDescriptionKey : "Your clock is out of sync with the service node network." ])
         @objc public static let randomSnodePoolUpdatingFailed = LokiAPIError(domain: "LokiAPIErrorDomain", code: 4, userInfo: [ NSLocalizedDescriptionKey : "Failed to update random service node pool." ])
+        @objc public static let missingSnodeVersion = LokiAPIError(domain: "LokiAPIErrorDomain", code: 5, userInfo: [ NSLocalizedDescriptionKey : "Missing service node version." ])
     }
     
     @objc(LKDestination)

SignalServiceKit/src/Loki/API/LokiFileServerProxy.swift

@@ -50,7 +50,7 @@ internal class LokiFileServerProxy : LokiHTTPClient {
             DispatchQueue.global().async {
                 let uncheckedSymmetricKey = try? Curve25519.generateSharedSecret(fromPublicKey: LokiFileServerProxy.fileServerPublicKey, privateKey: keyPair.privateKey)
                 guard let symmetricKey = uncheckedSymmetricKey else { return seal.reject(Error.symmetricKeyGenerationFailed) }
-                LokiAPI.getRandomSnode().then(on: DispatchQueue.global()) { proxy -> Promise<Any> in
+                LokiAPI.getFileServerProxy().then(on: DispatchQueue.global()) { proxy -> Promise<Any> in
                     let url = "\(proxy.address):\(proxy.port)/file_proxy"
                     guard let urlAsString = request.url?.absoluteString, let serverURLEndIndex = urlAsString.range(of: server)?.upperBound,
                         serverURLEndIndex < urlAsString.endIndex else { throw Error.endpointParsingFailed }

SignalServiceKit/src/Network/OWSSignalService.m

@@ -194,6 +194,9 @@ NSString *const kNSNotificationName_IsCensorshipCircumventionActiveDidChange =
     sessionManager.requestSerializer = [AFJSONRequestSerializer serializer];
     sessionManager.requestSerializer.HTTPShouldHandleCookies = NO;
     sessionManager.responseSerializer = [AFJSONResponseSerializer serializerWithReadingOptions:NSJSONReadingAllowFragments];
+    NSMutableSet<NSString *> *acceptableContentTypes = sessionManager.responseSerializer.acceptableContentTypes.mutableCopy;
+    [acceptableContentTypes addObject:@"text/plain"];
+    sessionManager.responseSerializer.acceptableContentTypes = acceptableContentTypes;
     return sessionManager;
 }