Add enumeration of encryption method.

Author: yangziy

ShadowsocksX-NG/Utils.swift

@@ -25,6 +25,27 @@ extension Data {
 }
 
 enum ProxyType:String {case pac="auto", global="global", manual="manual"};
+enum EncryptionMethod:String {
+    case AES_128_GCM = "aes-128-gcm"
+    case AES_192_GCM = "aes-192-gcm"
+    case AES_256_GCM = "aes-256-gcm"
+    case AES_128_CFB = "aes-128-cfb"
+    case AES_192_CFB = "aes-192-cfb"
+    case AES_256_CFB = "aes-256-cfb"
+    case AES_128_CTR = "aes-128-ctr"
+    case AES_192_CTR = "aes-192-ctr"
+    case AES_256_CTR = "aes-256-ctr"
+    case CAMELLIA_128_CFB = "camellia-128-cfb"
+    case CAMELLIA_192_CFB = "camellia-192-cfb"
+    case CAMELLIA_256_CFB = "camellia-256-cfb"
+    case BF_CFB = "bf-cfb"
+    case CHACHA20_IETF_POLY1305 = "chacha20-ietf-poly1305"
+    case XCHACHA20_IETF_POLY1305 = "xchacha20-ietf-poly1305"
+    case SALSA20 = "salsa20"
+    case CHACHA20 = "chacha20"
+    case CHACHA20_IETF = "chacha20-ietf"
+    case RC4_MD5 = "rc4-md5"
+}
 
 struct Globals {
     static var proxyType = ProxyType.pac
@@ -79,31 +100,11 @@ class Validator {
     static func method(_ str:String)  -> Bool {
         // Copy from PreferencesWindowController.swift
         // Better to make valid methods enumeration type.
-        return [
-            "aes-128-gcm",
-            "aes-192-gcm",
-            "aes-256-gcm",
-            "aes-128-cfb",
-            "aes-192-cfb",
-            "aes-256-cfb",
-            "aes-128-ctr",
-            "aes-192-ctr",
-            "aes-256-ctr",
-            "camellia-128-cfb",
-            "camellia-192-cfb",
-            "camellia-256-cfb",
-            "bf-cfb",
-            "chacha20-ietf-poly1305",
-            "xchacha20-ietf-poly1305",
-            "salsa20",
-            "chacha20",
-            "chacha20-ietf",
-            "rc4-md5",
-            ].contains(str);
+        return EncryptionMethod.init(rawValue: str) != nil
     }
 
     static func password(_ str:String)  -> Bool  {
-        return str != "";
+        return !str.isEmpty;
     }
 
     static func remark(_ str:String)  -> Bool  {