调整协议，只加密头部分

README.md

@@ -13,8 +13,9 @@ Run
 
     $ rebar3 shell
 
-The UDP listener is configured in `config/sys.config` and listens on port `16380`
+The UDP listener is configured in `config/sys.config`; the checked-in config
-by default. It accepts RelayKit UDP relay frames.
+listens on port `1443`, while the code fallback default is `16380`. It accepts
+RelayKit UDP relay frames.
 
 Protocol
 --------
@@ -29,7 +30,8 @@ The decrypted plaintext is one `RKP1` frame:
     magic(4) = "RKP1", version(1) = 1, type(1), reserved(2),
     stream_id(8), payload_len(4), payload(payload_len)
 
-Frame types are `open = 1`, `data = 2`, `close = 3`, and `error = 4`.
+Frame types are `open = 1`, `open_ack = 2`, `data = 3`, `close = 4`, and
+`error = 5`.
 `open` payload is binary encoded as:
 
     host_len(2), host(host_len), port(2),

apps/relay_server/src/chacha20_cipher.erl

@@ -1,45 +1,33 @@
 %%%-------------------------------------------------------------------
 %% @doc ChaCha20-Poly1305 helpers compatible with CryptoKit ChaChaPoly.
+%% 1. 只解决需要加解密数据的逻辑处理
 %% @end
 %%%-------------------------------------------------------------------
 
 -module(chacha20_cipher).
 
--export([encrypt/2, decrypt/2]).
+-export([encrypt/2, decrypt/4]).
 
 -define(KEY_BYTES, 32).
 -define(NONCE_BYTES, 12).
 -define(TAG_BYTES, 16).
 -define(AAD, <<>>).
 
-encrypt(PlainText, Key) when is_binary(PlainText) ->
+encrypt(PlainText, Key) when is_binary(PlainText), byte_size(Key) =:= ?KEY_BYTES ->
-    case valid_key(Key) of
-        true ->
     Nonce = crypto:strong_rand_bytes(?NONCE_BYTES),
-            try crypto:crypto_one_time_aead(
+    try crypto:crypto_one_time_aead(chacha20_poly1305, Key, Nonce, PlainText, ?AAD, true) of
-                    chacha20_poly1305, Key, Nonce, PlainText, ?AAD, true
-                ) of
         {CipherText, Tag} ->
             {ok, <<Nonce/binary, CipherText/binary, Tag/binary>>}
     catch
         _Class:_Reason ->
             {error, crypto_failed}
     end;
-        false ->
+
-            {error, invalid_key}
-    end;
 encrypt(_PlainText, _Key) ->
     {error, invalid_plaintext}.
 
-decrypt(Combined, Key) when is_binary(Combined), byte_size(Combined) >= ?NONCE_BYTES + ?TAG_BYTES ->
+decrypt(Nonce, CipherText, Tag, Key) when is_binary(Nonce), is_binary(CipherText), is_binary(Tag), is_binary(Key) ->
-    case valid_key(Key) of
+    try crypto:crypto_one_time_aead(chacha20_poly1305, Key, Nonce, CipherText, ?AAD, Tag, false) of
-        true ->
-            <<Nonce:?NONCE_BYTES/binary, Rest/binary>> = Combined,
-            CipherTextBytes = byte_size(Rest) - ?TAG_BYTES,
-            <<CipherText:CipherTextBytes/binary, Tag:?TAG_BYTES/binary>> = Rest,
-            try crypto:crypto_one_time_aead(
-                    chacha20_poly1305, Key, Nonce, CipherText, ?AAD, Tag, false
-                ) of
         error ->
             {error, authentication_failed};
         PlainText ->
@@ -47,16 +35,4 @@ decrypt(Combined, Key) when is_binary(Combined), byte_size(Combined) >= ?NONCE_B
     catch
         _Class:_Reason ->
             {error, crypto_failed}
-            end;
+    end.
-        false ->
-            {error, invalid_key}
-    end;
-decrypt(Combined, _Key) when is_binary(Combined) ->
-    {error, ciphertext_too_short};
-decrypt(_Combined, _Key) ->
-    {error, invalid_ciphertext}.
-
-valid_key(Key) when is_binary(Key), byte_size(Key) =:= ?KEY_BYTES ->
-    true;
-valid_key(_Key) ->
-    false.

apps/relay_server/src/relay_server_udp_handler.erl

@@ -13,17 +13,6 @@
 
 -define(TCP_OPTIONS, [binary, {packet, raw}, {active, once}, {nodelay, true}]).
 
--define(CHACHA20_KEY, <<
-    16#9F, 16#4A, 16#6C, 16#0D,
-    16#8B, 16#21, 16#7E, 16#3F,
-    16#42, 16#D9, 16#AA, 16#78,
-    16#13, 16#C5, 16#E2, 16#B6,
-    16#F0, 16#A9, 16#27, 16#BC,
-    16#6D, 16#31, 16#E8, 16#4C,
-    16#55, 16#FA, 16#10, 16#2A,
-    16#7E, 16#9D, 16#3C, 16#BB
-    >>).
-
 -record(stream, {
     id :: non_neg_integer(),
     socket :: inet:socket(),
@@ -38,7 +27,6 @@
     peer :: {inet:ip_address(), inet:port_number()},
     idle_timeout :: timeout(),
     connect_timeout :: timeout(),
-    cipher_key :: binary(),
     users = #{} :: #{binary() => binary()},
     streams = #{} :: #{non_neg_integer() => stream()},
     sockets = #{} :: #{inet:socket() => non_neg_integer()}
@@ -57,7 +45,6 @@ init([{udp, Server, _Sock}, Peer, IdleTimeout, ConnectTimeout, Users]) ->
         peer = Peer,
         idle_timeout = IdleTimeout,
         connect_timeout = ConnectTimeout,
-        cipher_key = ?CHACHA20_KEY,
         users = normalize_users(Users)
     }, IdleTimeout}.
 
@@ -90,16 +77,7 @@ terminate(_Reason, #state{streams = Streams}) ->
 code_change(_OldVsn, State, _Extra) ->
     {ok, State}.
 
-handle_encrypted_datagram(Packet, State = #state{idle_timeout = IdleTimeout, cipher_key = Key}) ->
+handle_encrypted_datagram(Packet, State = #state{idle_timeout = IdleTimeout}) ->
-    case chacha20_cipher:decrypt(Packet, Key) of
-        {ok, PlainPacket} ->
-            handle_datagram(PlainPacket, State);
-        {error, Reason} ->
-            logger:error("UDP relay ignored undecryptable datagram: ~p", [Reason]),
-            {noreply, State, IdleTimeout}
-    end.
-
-handle_datagram(Packet, State = #state{idle_timeout = IdleTimeout}) ->
     case relay_server_udp_protocol:decode(Packet) of
         {ok, connection_close} ->
             {stop, normal, State};
@@ -246,21 +224,19 @@ remove_stream(StreamId, State = #state{streams = Streams, sockets = Sockets}) ->
 close_remote(#stream{socket = Socket}) ->
     gen_tcp:close(Socket).
 
-send_frame(_Type, _StreamId, <<>>, _State) ->
+send_frame(Type, StreamId, <<Part:1200/binary, Rest/binary>>, State)
-    ok;
+        when byte_size(Rest) > 0 ->
-send_frame(Type, StreamId, <<Part:1200/binary, Rest/binary>>, State) ->
     case send_frame0(Type, StreamId, Part, State) of
         ok ->
             send_frame(Type, StreamId, Rest, State);
         Error ->
             Error
     end;
-send_frame(Type, StreamId, Rest, State) ->
+send_frame(Type, StreamId, Payload, State) ->
-    send_frame0(Type, StreamId, Rest, State).
+    send_frame0(Type, StreamId, Payload, State).
 
-send_frame0(Type, StreamId, Part, #state{server = Server, peer = Peer, cipher_key = Key}) ->
+send_frame0(Type, StreamId, Part, #state{server = Server, peer = Peer}) ->
-    PlainPacket = relay_server_udp_protocol:encode(Type, StreamId, Part),
+    case relay_server_udp_protocol:encode(Type, StreamId, Part) of
-    case chacha20_cipher:encrypt(PlainPacket, Key) of
         {ok, Packet} ->
             logger:error("UDP relay encrypt packet size: ~p", [byte_size(Packet)]),
             Server ! {datagram, Peer, Packet},

apps/relay_server/src/relay_server_udp_protocol.erl

@@ -14,28 +14,52 @@
 
 -define(CONNECTION_CLOSE, 16#FF).
 
+-define(CHACHA20_KEY, <<
+    16#9F, 16#4A, 16#6C, 16#0D,
+    16#8B, 16#21, 16#7E, 16#3F,
+    16#42, 16#D9, 16#AA, 16#78,
+    16#13, 16#C5, 16#E2, 16#B6,
+    16#F0, 16#A9, 16#27, 16#BC,
+    16#6D, 16#31, 16#E8, 16#4C,
+    16#55, 16#FA, 16#10, 16#2A,
+    16#7E, 16#9D, 16#3C, 16#BB
+>>).
+
+decode(<<Nonce:12/binary, CipherHead:20/binary, Tag:16/binary, Body/binary>>) ->
+    case chacha20_cipher:decrypt(Nonce, CipherHead, Tag, ?CHACHA20_KEY) of
+        {ok, PlainText} ->
+            decode0(PlainText, Body);
+        Error ->
+            Error
+    end.
 %% 全局控制指令也要加密处理
-decode(<<"RKP1", ?VERSION:8, ?CONNECTION_CLOSE:8, 0:16, 0:64, 0:32, _Rest/binary>>) ->
+decode0(<<"RKP1", ?VERSION:8, ?CONNECTION_CLOSE:8, 0:16, 0:64, 0:32>>, _Body) ->
     {ok, connection_close};
-decode(<<"RKP1", ?VERSION:8, TypeNo:8, 0:16, StreamId:64, PayloadLen:32, Rest/binary>>) ->
+decode0(<<"RKP1", ?VERSION:8, TypeNo:8, 0:16, StreamId:64, PayloadLen:32>>, Body) when is_binary(Body) ->
-    case {type(TypeNo), byte_size(Rest) >= PayloadLen} of
+    case {type(TypeNo), byte_size(Body) >= PayloadLen} of
         {undefined, _} ->
             {error, unknown_frame_type};
         {_, false} ->
             {error, truncated_frame};
         {Type, true} ->
-            <<Payload:PayloadLen/binary, _Trailing/binary>> = Rest,
+            <<Payload:PayloadLen/binary, _Trailing/binary>> = Body,
             {ok, {Type, StreamId, Payload}}
     end;
-decode(Packet) when byte_size(Packet) < ?HEADER_LENGTH ->
+decode0(Header, _Body) when byte_size(Header) < ?HEADER_LENGTH ->
     {error, frame_too_short};
-decode(_Packet) ->
+decode0(_Header, _Body) ->
     {error, bad_frame_header}.
 
-encode(Type, StreamId, Payload) when is_binary(Payload) ->
+encode(Type, StreamId, Payload) when is_atom(Type), is_integer(StreamId), is_binary(Payload) ->
     TypeNo = type_no(Type),
     PayloadLen = byte_size(Payload),
-    <<"RKP1", ?VERSION:8, TypeNo:8, 0:16, StreamId:64, PayloadLen:32, Payload/binary>>.
+    Head = <<"RKP1", ?VERSION:8, TypeNo:8, 0:16, StreamId:64, PayloadLen:32>>,
+    case chacha20_cipher:encrypt(Head, ?CHACHA20_KEY) of
+        {ok, EncryptHead} ->
+            <<EncryptHead/binary, Payload/binary>>;
+        Error ->
+            Error
+    end.
 
 decode_open_request(<<HostLen:16, Host:HostLen/binary, Port:16,
         UsernameLen:16, Username:UsernameLen/binary,