refine factory

shadowsocks-csharp/Encrypt/EncryptorFactory.cs

@@ -1,16 +1,43 @@
 
+using System;
+using System.Collections.Generic;
+using System.Reflection;
 namespace Shadowsocks.Encrypt
 {
     public static class EncryptorFactory
     {
-        public static IEncryptor GetEncryptor(string method, string password)
+        private static Dictionary<string, Type> _registeredEncryptors;
+
+        private static Type[] _constructorTypes = new Type[] { typeof(string), typeof(string) };
+
+        static EncryptorFactory()
         {
-            if (string.IsNullOrEmpty(method) || method.ToLowerInvariant() == "table")
+            _registeredEncryptors = new Dictionary<string, Type>();
+            foreach (string method in TableEncryptor.SupportedCiphers())
+            {
+                _registeredEncryptors.Add(method, typeof(TableEncryptor));
+            }
+            foreach (string method in PolarSSLEncryptor.SupportedCiphers())
+            {
+                _registeredEncryptors.Add(method, typeof(PolarSSLEncryptor));
+            }
+            foreach (string method in SodiumEncryptor.SupportedCiphers())
             {
-                return new TableEncryptor(method, password);
+                _registeredEncryptors.Add(method, typeof(SodiumEncryptor));
             }
+        }
 
-            return new SodiumEncryptor(method, password);
+        public static IEncryptor GetEncryptor(string method, string password)
+        {
+            if (string.IsNullOrEmpty(method))
+            {
+                method = "table";
+            }
+            method = method.ToLowerInvariant();
+            Type t = _registeredEncryptors[method];
+            ConstructorInfo c = t.GetConstructor(_constructorTypes);
+            IEncryptor result = (IEncryptor)c.Invoke(new object[] { method, password });
+            return result;
         }
     }
 }

shadowsocks-csharp/Encrypt/PolarSSLEncryptor.cs

@@ -22,15 +22,22 @@ namespace Shadowsocks.Encrypt
             InitKey(method, password);
         }
 
-        protected override Dictionary<string, int[]> getCiphers()
-        {
-            return new Dictionary<string, int[]> {
+        private static Dictionary<string, int[]> _ciphers = new Dictionary<string, int[]> {
                 {"aes-128-cfb", new int[]{16, 16, CIPHER_AES, PolarSSL.AES_CTX_SIZE}},
                 {"aes-192-cfb", new int[]{24, 16, CIPHER_AES, PolarSSL.AES_CTX_SIZE}},
                 {"aes-256-cfb", new int[]{32, 16, CIPHER_AES, PolarSSL.AES_CTX_SIZE}},
                 {"rc4", new int[]{16, 0, CIPHER_RC4, PolarSSL.ARC4_CTX_SIZE}},
                 {"rc4-md5", new int[]{16, 16, CIPHER_RC4, PolarSSL.ARC4_CTX_SIZE}},
-            };
+        };
+
+        public static List<string> SupportedCiphers()
+        {
+            return new List<string>(_ciphers.Keys);
+        }
+
+        protected override Dictionary<string, int[]> getCiphers()
+        {
+            return _ciphers;
         }
 
         protected override void initCipher(byte[] iv, bool isCipher)

shadowsocks-csharp/Encrypt/SodiumEncryptor.cs

@@ -27,12 +27,19 @@ namespace Shadowsocks.Encrypt
             _decryptBuf = new byte[MAX_INPUT_SIZE + SODIUM_BLOCK_SIZE];
         }
 
-        protected override Dictionary<string, int[]> getCiphers()
-        {
-            return new Dictionary<string, int[]> {
+        private static Dictionary<string, int[]> _ciphers = new Dictionary<string, int[]> {
                 {"salsa20", new int[]{32, 8, CIPHER_SALSA20, PolarSSL.AES_CTX_SIZE}},
                 {"chacha20", new int[]{32, 8, CIPHER_CHACHA20, PolarSSL.AES_CTX_SIZE}},
-            }; ;
+        };
+
+        protected override Dictionary<string, int[]> getCiphers()
+        {
+            return _ciphers;
+        }
+
+        public static List<string> SupportedCiphers()
+        {
+            return new List<string>(_ciphers.Keys);
         }
 
         protected override void cipherUpdate(bool isCipher, int length, byte[] buf, byte[] outbuf)

shadowsocks-csharp/Encrypt/TableEncryptor.cs

@@ -1,4 +1,5 @@
 using System;
+using System.Collections.Generic;
 
 namespace Shadowsocks.Encrypt
 {
@@ -25,6 +26,11 @@ namespace Shadowsocks.Encrypt
             }
         }
 
+        public static List<string> SupportedCiphers()
+        {
+            return new List<string>(new string[]{"table"});
+        }
+
         public override void Encrypt(byte[] buf, int length, byte[] outbuf, out int outlength)
         {
             byte[] result = new byte[length];