init project

.gitignore

@@ -0,0 +1,20 @@
+.rebar3
+_build
+_checkouts
+_vendor
+.eunit
+*.o
+*.beam
+*.plt
+*.swp
+*.swo
+.erlang.cookie
+ebin
+log
+erl_crash.dump
+.rebar
+logs
+.idea
+*.iml
+rebar3.crashdump
+*~

LICENSE.md

@@ -0,0 +1,186 @@
+# Apache License
+Version 2.0, January 2004
+
+http://www.apache.org/licenses/
+
+TERMS AND CONDITIONS FOR USE, REPRODUCTION, AND DISTRIBUTION
+
+## 1. Definitions.
+
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+You may add Your own copyright statement to Your modifications and may provide
+additional or different license terms and conditions for use, reproduction, or
+distribution of Your modifications, or for any such Derivative Works as a whole,
+provided Your use, reproduction, and distribution of the Work otherwise complies
+with the conditions stated in this License.
+
+## 5. Submission of Contributions.
+
+Unless You explicitly state otherwise, any Contribution intentionally submitted
+for inclusion in the Work by You to the Licensor shall be under the terms and
+conditions of this License, without any additional terms or conditions.
+Notwithstanding the above, nothing herein shall supersede or modify the terms of
+any separate license agreement you may have executed with Licensor regarding
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+
+## 6. Trademarks.
+
+This License does not grant permission to use the trade names, trademarks,
+service marks, or product names of the Licensor, except as required for
+reasonable and customary use in describing the origin of the Work and
+reproducing the content of the NOTICE file.
+
+## 7. Disclaimer of Warranty.
+
+Unless required by applicable law or agreed to in writing, Licensor provides the
+Work (and each Contributor provides its Contributions) on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied,
+including, without limitation, any warranties or conditions of TITLE, NON-
+INFRINGEMENT, MERCHANTABILITY, or FITNESS FOR A PARTICULAR PURPOSE. You are
+solely responsible for determining the appropriateness of using or
+redistributing the Work and assume any risks associated with Your exercise of
+permissions under this License.
+
+## 8. Limitation of Liability.
+
+In no event and under no legal theory, whether in tort (including negligence),
+contract, or otherwise, unless required by applicable law (such as deliberate
+and grossly negligent acts) or agreed to in writing, shall any Contributor be
+liable to You for damages, including any direct, indirect, special, incidental,
+or consequential damages of any character arising as a result of this License or
+out of the use or inability to use the Work (including but not limited to
+damages for loss of goodwill, work stoppage, computer failure or malfunction, or
+any and all other commercial damages or losses), even if such Contributor has
+been advised of the possibility of such damages.
+
+## 9. Accepting Warranty or Additional Liability.
+
+While redistributing the Work or Derivative Works thereof, You may choose to
+offer, and charge a fee for, acceptance of support, warranty, indemnity, or
+other liability obligations and/or rights consistent with this License. However,
+in accepting such obligations, You may act only on Your own behalf and on Your
+sole responsibility, not on behalf of any other Contributor, and only if You
+agree to indemnify, defend, and hold each Contributor harmless for any liability
+incurred by, or claims asserted against, such Contributor by reason of your
+accepting any such warranty or additional liability.
+
+END OF TERMS AND CONDITIONS
+
+Copyright 2026, anlicheng <244108715@qq.com>.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.

README.md

@@ -0,0 +1,9 @@
+sdlan_assist
+=====
+
+An OTP application
+
+Build
+-----
+
+    $ rebar3 compile

apps/sdlan_assist/src/sdlan_assist_app.erl

@@ -0,0 +1,18 @@
+%%%-------------------------------------------------------------------
+%% @doc sdlan_assist public API
+%% @end
+%%%-------------------------------------------------------------------
+
+-module(sdlan_assist_app).
+
+-behaviour(application).
+
+-export([start/2, stop/1]).
+
+start(_StartType, _StartArgs) ->
+    sdlan_assist_sup:start_link().
+
+stop(_State) ->
+    ok.
+
+%% internal functions

apps/sdlan_assist/src/sdlan_assist_peer_server.erl

@@ -0,0 +1,122 @@
+%%%-------------------------------------------------------------------
+%%% @author anlicheng
+%%% @copyright (C) 2026, <COMPANY>
+%%% @doc
+%%%
+%%% @end
+%%% Created : 22. 1月 2026 16:01
+%%%-------------------------------------------------------------------
+-module(sdlan_assist_peer_server).
+-author("anlicheng").
+
+-behaviour(gen_server).
+
+%% API
+-export([start_link/0]).
+-export([stun_relay/3]).
+
+%% gen_server callbacks
+-export([init/1, handle_call/3, handle_cast/2, handle_info/2, terminate/2, code_change/3]).
+
+-define(SERVER, ?MODULE).
+
+%% stun消息转发
+-define(PACKET_STUN_PROBE_RELAY, 16#3a).
+
+-record(state, {
+    socket :: inet:socket()
+}).
+
+%%%===================================================================
+%%% API
+%%%===================================================================
+
+-spec stun_relay(Ip :: inet:ip_address(), Port :: integer(), Reply :: binary()) -> ok.
+stun_relay(Ip, Port, Reply) when is_integer(Port), is_binary(Reply) ->
+    gen_server:cast(?SERVER, {stun_relay, Ip, Port, Reply}).
+
+%% @doc Spawns the server and registers the local name (unique)
+-spec(start_link() ->
+    {ok, Pid :: pid()} | ignore | {error, Reason :: term()}).
+start_link() ->
+    gen_server:start_link({local, ?SERVER}, ?MODULE, [], []).
+
+%%%===================================================================
+%%% gen_server callbacks
+%%%===================================================================
+
+%% @private
+%% @doc Initializes the server
+-spec(init(Args :: term()) ->
+    {ok, State :: #state{}} | {ok, State :: #state{}, timeout() | hibernate} |
+    {stop, Reason :: term()} | ignore).
+init([]) ->
+    {ok, Props} = application:get_env(sdlan_assist, stun_peer_server),
+    Port = proplists:get_value(port, Props),
+
+    Opts = [
+        binary,
+        {active, true},
+        {reuseaddr, true}
+    ],
+    {ok, Socket} = gen_udp:open(Port, Opts),
+    inet_udp:controlling_process(Socket, self()),
+    logger:debug("[sdlan_assist_peer_server] started at port: ~p", [Port]),
+    {ok, #state{socket = Socket}}.
+
+%% @private
+%% @doc Handling call messages
+-spec(handle_call(Request :: term(), From :: {pid(), Tag :: term()},
+    State :: #state{}) ->
+    {reply, Reply :: term(), NewState :: #state{}} |
+    {reply, Reply :: term(), NewState :: #state{}, timeout() | hibernate} |
+    {noreply, NewState :: #state{}} |
+    {noreply, NewState :: #state{}, timeout() | hibernate} |
+    {stop, Reason :: term(), Reply :: term(), NewState :: #state{}} |
+    {stop, Reason :: term(), NewState :: #state{}}).
+handle_call(_Request, _From, State = #state{}) ->
+    {reply, ok, State}.
+
+%% @private
+%% @doc Handling cast messages
+-spec(handle_cast(Request :: term(), State :: #state{}) ->
+    {noreply, NewState :: #state{}} |
+    {noreply, NewState :: #state{}, timeout() | hibernate} |
+    {stop, Reason :: term(), NewState :: #state{}}).
+handle_cast(_Cast, State) ->
+    {noreply, State}.
+
+%% @private
+%% @doc Handling all non call/cast messages
+-spec(handle_info(Info :: timeout() | term(), State :: #state{}) ->
+    {noreply, NewState :: #state{}} |
+    {noreply, NewState :: #state{}, timeout() | hibernate} |
+    {stop, Reason :: term(), NewState :: #state{}}).
+handle_info({udp, _Sock, _Ip, Port, <<?PACKET_STUN_PROBE_RELAY:8, Ip0, Ip1, Ip2, Ip3, Port:16, Reply/binary>>}, State = #state{socket = Sock}) ->
+    ok = gen_udp:send(Sock, {Ip0, Ip1, Ip2, Ip3}, Port, Reply),
+    {noreply, State};
+handle_info(Info, State = #state{}) ->
+    logger:notice("[sdlan_assist_peer_server] get a unknown info: ~p", [Info]),
+    {noreply, State}.
+
+%% @private
+%% @doc This function is called by a gen_server when it is about to
+%% terminate. It should be the opposite of Module:init/1 and do any
+%% necessary cleaning up. When it returns, the gen_server terminates
+%% with Reason. The return value is ignored.
+-spec(terminate(Reason :: (normal | shutdown | {shutdown, term()} | term()),
+    State :: #state{}) -> term()).
+terminate(_Reason, _State = #state{}) ->
+    ok.
+
+%% @private
+%% @doc Convert process state when code is changed
+-spec(code_change(OldVsn :: term() | {down, term()}, State :: #state{},
+    Extra :: term()) ->
+    {ok, NewState :: #state{}} | {error, Reason :: term()}).
+code_change(_OldVsn, State = #state{}, _Extra) ->
+    {ok, State}.
+
+%%%===================================================================
+%%% Internal functions
+%%%===================================================================

apps/sdlan_assist/src/sdlan_assist_sup.erl

@@ -0,0 +1,42 @@
+%%%-------------------------------------------------------------------
+%% @doc sdlan_assist top level supervisor.
+%% @end
+%%%-------------------------------------------------------------------
+
+-module(sdlan_assist_sup).
+
+-behaviour(supervisor).
+
+-export([start_link/0]).
+
+-export([init/1]).
+
+-define(SERVER, ?MODULE).
+
+start_link() ->
+    supervisor:start_link({local, ?SERVER}, ?MODULE, []).
+
+%% sup_flags() = #{strategy => strategy(),         % optional
+%%                 intensity => non_neg_integer(), % optional
+%%                 period => pos_integer()}        % optional
+%% child_spec() = #{id => child_id(),       % mandatory
+%%                  start => mfargs(),      % mandatory
+%%                  restart => restart(),   % optional
+%%                  shutdown => shutdown(), % optional
+%%                  type => worker(),       % optional
+%%                  modules => modules()}   % optional
+init([]) ->
+    SupFlags = #{ strategy => one_for_one, intensity => 1000, period => 3600},
+    ChildSpecs = [
+        #{
+            id => sdlan_assist_peer_server,
+            start => {sdlan_assist_peer_server, start_link, []},
+            restart => permanent,
+            shutdown => 2000,
+            type => worker,
+            modules => ['sdlan_assist_peer_server']
+        }
+    ],
+    {ok, {SupFlags, ChildSpecs}}.
+
+%% internal functions

config/sys.config

@@ -0,0 +1,34 @@
+[
+  {sdlan_assist, [
+    {stun_peer_server, [
+      {port, 1366}
+    ]}
+  ]},
+
+  %% 系统日志配置，系统日志为lager, 支持日志按日期自动分割
+  {kernel, [
+    %% 设置 Logger 的 primary log level
+    {logger_level, debug},
+    {logger, [
+      {handler, default, logger_std_h,
+        #{
+          level => debug,
+          formatter => {logger_formatter, #{template => [time, " [", level, "] ", msg, "\n"]}}
+        }
+      },
+
+      {handler, disk, logger_disk_log_h,
+        #{
+          level => debug,
+          config => #{
+          file => "log/debug.log",
+          max_no_files => 10,
+          max_no_bytes => 524288000
+        },
+          formatter => {logger_formatter, #{template => [time, " [", level, "] ", msg, "\n"]}}
+        }
+      }
+
+    ]}
+  ]}
+].

config/vm.args

@@ -0,0 +1,6 @@
+-sname sdlan_assist
+
+-setcookie sdlan_assist_cookie
+
++K true
++A30

rebar.config

@@ -0,0 +1,39 @@
+{erl_opts, [debug_info]}.
+{deps, [
+    {sync, ".*", {git, "https://github.com/rustyio/sync.git", {branch, "master"}}}
+]}.
+
+{relx, [
+    {release, {sdlan_assist, "0.1.0"}, [
+        sdlan_assist,
+        sasl
+    ]},
+
+    {mode, dev},
+
+    %% automatically picked up if the files
+    %% exist but can be set manually, which
+    %% is required if the names aren't exactly
+    %% sys.config and vm.args
+    {sys_config, "./config/sys.config"},
+    {vm_args, "./config/vm.args"}
+
+    %% the .src form of the configuration files do
+    %% not require setting RELX_REPLACE_OS_VARS
+    %% {sys_config_src, "./config/sys.config.src"},
+    %% {vm_args_src, "./config/vm.args.src"}
+]}.
+
+{profiles, [
+    %% prod is the default mode when prod
+    %% profile is used, so does not have
+    %% to be explicitly included like this
+    {prod, [
+        {relx, [
+            {mode, prod}
+
+            %% use minimal mode to exclude ERTS
+            %% {mode, minimal}
+        ]}
+    ]}
+]}.

rebar.lock

@@ -0,0 +1,12 @@
+{"1.2.0",
+[{<<"fs">>,{pkg,<<"fs">>,<<"6.1.1">>},1},
+ {<<"sync">>,
+  {git,"https://github.com/rustyio/sync.git",
+       {ref,"4e909f69d3d0db21a6d7128b20748819e415c9eb"}},
+  0}]}.
+[
+{pkg_hash,[
+ {<<"fs">>, <<"9D147B944D60CFA48A349F12D06C8EE71128F610C90870BDF9A6773206452ED0">>}]},
+{pkg_hash_ext,[
+ {<<"fs">>, <<"EF94E95FFE79916860649FED80AC62B04C322B0BB70F5128144C026B4D171F8B">>}]}
+].