use v3/lsrpc endpoint for more compact (base64) file downloads

SignalServiceKit/src/Loki/API/DotNetAPI.swift

@@ -127,11 +127,11 @@ public class DotNetAPI : NSObject {
         return attempt(maxRetryCount: maxRetryCount, recoveringOn: SnodeAPI.workQueue) {
             serverPublicKeyPromise.then2 { serverPublicKey in
                 return OnionRequestAPI.sendOnionRequest(request, to: host, using: serverPublicKey, isJSONRequired: false).map2 { json in
-                    guard let body = json["body"] as? JSON, let data = body["data"] as? [UInt8] else {
+                    guard let body = json["result"] as? String, let data = Data(base64Encoded: body) else {
                         print("[Loki] Couldn't parse attachment from: \(json).")
                         throw DotNetAPIError.parsingFailed
                     }
-                    return Data(data)
+                    return data
                 }
             }
         }

SignalServiceKit/src/Loki/API/Onion Requests/OnionRequestAPI+Encryption.swift

@@ -26,7 +26,7 @@ extension OnionRequestAPI {
                     let plaintext = try encode(ciphertext: payloadAsData, json: [ "headers" : "" ])
                     let result = try EncryptionUtilities.encrypt(plaintext, using: snodeX25519PublicKey)
                     seal.fulfill(result)
-                case .server(_, let serverX25519PublicKey):
+                case .server(_, _, let serverX25519PublicKey):
                     let plaintext = try JSONSerialization.data(withJSONObject: payload, options: [ .fragmentsAllowed ])
                     let result = try EncryptionUtilities.encrypt(plaintext, using: serverX25519PublicKey)
                     seal.fulfill(result)
@@ -47,8 +47,8 @@ extension OnionRequestAPI {
             case .snode(let snode):
                 guard let snodeED25519PublicKey = snode.publicKeySet?.ed25519Key else { return seal.reject(Error.snodePublicKeySetMissing) }
                 parameters = [ "destination" : snodeED25519PublicKey ]
-            case .server(let host, _):
+            case .server(let host, let target, _):
-                parameters = [ "host" : host, "target" : "/loki/v2/lsrpc", "method" : "POST" ]
+                parameters = [ "host" : host, "target" : target, "method" : "POST" ]
             }
             parameters["ephemeral_key"] = previousEncryptionResult.ephemeralPublicKey.toHexString()
             let x25519PublicKey: String
@@ -56,7 +56,7 @@ extension OnionRequestAPI {
             case .snode(let snode):
                 guard let snodeX25519PublicKey = snode.publicKeySet?.x25519Key else { return seal.reject(Error.snodePublicKeySetMissing) }
                 x25519PublicKey = snodeX25519PublicKey
-            case .server(_, let serverX25519PublicKey):
+            case .server(_, _, let serverX25519PublicKey):
                 x25519PublicKey = serverX25519PublicKey
             }
             do {

SignalServiceKit/src/Loki/API/Onion Requests/OnionRequestAPI.swift

@@ -24,7 +24,7 @@ public enum OnionRequestAPI {
     // MARK: Destination
     internal enum Destination {
         case snode(Snode)
-        case server(host: String, x25519PublicKey: String)
+        case server(host: String, target: String, x25519PublicKey: String)
     }
 
     // MARK: Error
@@ -280,7 +280,7 @@ public enum OnionRequestAPI {
     }
     
     /// Sends an onion request to `server`. Builds new paths as needed.
-    internal static func sendOnionRequest(_ request: NSURLRequest, to server: String, using x25519PublicKey: String, isJSONRequired: Bool = true) -> Promise<JSON> {
+    internal static func sendOnionRequest(_ request: NSURLRequest, to server: String, target: String = "/loki/v3/lsrpc", using x25519PublicKey: String, isJSONRequired: Bool = true) -> Promise<JSON> {
         var rawHeaders = request.allHTTPHeaderFields ?? [:]
         rawHeaders.removeValue(forKey: "User-Agent")
         var headers: JSON = rawHeaders.mapValues { value in
@@ -323,7 +323,7 @@ public enum OnionRequestAPI {
             "method" : request.httpMethod!,
             "headers" : headers
         ]
-        let destination = Destination.server(host: host, x25519PublicKey: x25519PublicKey)
+        let destination = Destination.server(host: host, target: target, x25519PublicKey: x25519PublicKey)
         let promise = sendOnionRequest(with: payload, to: destination, isJSONRequired: isJSONRequired)
         promise.catch2 { error in
             print("[Loki] [Onion Request API] Couldn't reach server: \(url) due to error: \(error).")