fix

apps/dns_proxy/src/dns_handler.erl

@@ -13,6 +13,8 @@
 -include_lib("dns_erlang/include/dns_records.hrl").
 -include_lib("dns_erlang/include/dns_terms.hrl").
 
+-define(RESOLVER_POOL, dns_resolver_pool).
+
 -export([start_link/4, init/4]).
 
 start_link(Sock, Ip, Port, Packet) ->
@@ -36,11 +38,15 @@ init(Sock, Ip, Port, Packet) ->
             exit(normal)
     end.
 
-forward_to_upstream(Sock, Ip, Port, Packet) ->
+forward_to_upstream(Sock, SrcIp, SrcPort, Request) ->
-    {SendSock, {UpIP, UpPort}} = dns_socket_pool:get_socket(),
+    {ok, DNSServers} = application:get_env(dns_proxy, public_dns_servers),
-    ok = gen_udp:send(SendSock, UpIP, UpPort, Packet),
+
+    ReceiverPid = self(),
+    Ref = make_ref(),
+    poolboy:transaction(?RESOLVER_POOL, fun(Pid) ->
+        dns_resolver:forward(Pid, ReceiverPid, Ref, TargetIp, TargetPort, Request)
+                                        end),
 
-    inet:setopts(SendSock, [{active, once}]),
     receive
         {udp, SendSock, _UIp, _UPort, Resp} ->
             gen_udp:send(Sock, Ip, Port, Resp)

apps/dns_proxy/src/dns_handler2.erl

@@ -0,0 +1,151 @@
+%%%-------------------------------------------------------------------
+%%% @author anlicheng
+%%% @copyright (C) 2025, <COMPANY>
+%%% @doc
+%%%
+%%% @end
+%%% Created : 03. 12月 2025 23:00
+%%%-------------------------------------------------------------------
+-module(dns_handler2).
+-author("anlicheng").
+
+-behaviour(gen_server).
+
+-include_lib("dns_erlang/include/dns.hrl").
+-include_lib("dns_erlang/include/dns_records.hrl").
+-include_lib("dns_erlang/include/dns_terms.hrl").
+
+%% API
+-export([start_link/4]).
+
+%% gen_server callbacks
+-export([init/1, handle_call/3, handle_cast/2, handle_info/2, terminate/2, code_change/3]).
+-export([handle/1]).
+
+-define(SERVER, ?MODULE).
+-define(RESOLVER_POOL, dns_resolver_pool).
+%% 转发的超时设置
+-define(UPSTREAM_TIMEOUT, 1000).
+
+-record(state, {
+    socket,
+    src_ip,
+    src_port,
+    packet,
+    dns_servers = []
+}).
+
+%%%===================================================================
+%%% API
+%%%===================================================================
+
+start_link(Sock, Ip, Port, Packet) ->
+    gen_server:start_link(?MODULE, [Sock, Ip, Port, Packet], []).
+
+handle(Pid) when is_pid(Pid) ->
+    gen_server:cast(Pid, handle).
+
+%%%===================================================================
+%%% 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([Sock, SrcIp, SrcPort, Packet]) ->
+    {ok, DNSServers} = application:get_env(dns_proxy, public_dns_servers),
+    {ok, #state{dns_servers = DNSServers, socket = Sock, src_ip = SrcIp, src_port = SrcPort, packet = Packet}}.
+
+%% @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(handle, State = #state{socket = Sock, src_ip = SrcIp, src_port = SrcPort, packet = Packet, dns_servers = [{DnsIp, DnsPort}|RestDnsServers]}) ->
+    case dns:decode_message(Packet) of
+        Msg = #dns_message{qc = 1, questions = [Question|_]} ->
+            Qname = Question#dns_query.name,
+            lager:debug("[dns_handler] qname: ~p", [Qname]),
+            case dns_cache:lookup(Qname) of
+                {hit, R} ->
+                    Resp = build_response(Msg, R),
+                    gen_udp:send(Sock, SrcIp, SrcPort, dns:encode_message(Resp)),
+                    {stop, normal};
+                miss ->
+                    lager:debug("[dns_handler] cache is miss"),
+                    forward_to_upstream(DnsIp, DnsPort, Packet),
+                    %% 开启定时器，超时后递归请求后面的服务
+                    erlang:start_timer(?UPSTREAM_TIMEOUT, self(), trigger_next),
+                    {noreply, State#state{dns_servers = RestDnsServers}}
+            end;
+        Other ->
+            lager:warning("[] decode msg get error: ~p", [Other]),
+            {stop, normal}
+    end.
+
+%% @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{}}).
+%% 处理超时重试
+handle_info({timeout, _, trigger_next}, State = #state{packet = Packet, dns_servers = [{DnsIp, DnsPort}|RestDnsServers]}) ->
+    forward_to_upstream(DnsIp, DnsPort, Packet),
+    erlang:start_timer(?UPSTREAM_TIMEOUT, self(), trigger_next),
+    {noreply, State#state{dns_servers = RestDnsServers}};
+handle_info({timeout, _, trigger_next}, State = #state{dns_servers = []}) ->
+    {stop, normal, State};
+
+%% 收到请求
+handle_info({dns_resolver_reply, Resp}, State = #state{socket = Sock, src_ip = SrcIp, src_port = SrcPort}) ->
+    gen_udp:send(Sock, SrcIp, SrcPort, dns:encode_message(Resp)),
+    {stop, normal, 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
+%%%===================================================================
+
+forward_to_upstream(TargetIp, TargetPort, Request) ->
+    ReceiverPid = self(),
+    poolboy:transaction(?RESOLVER_POOL, fun(Pid) ->
+        dns_resolver:forward(Pid, ReceiverPid, TargetIp, TargetPort, Request)
+                                        end).
+
+build_response(Req, RR) ->
+    Msg = Req,
+    Msg#dns_message{answers=[RR], qr=true, aa=true}.

apps/dns_proxy/src/dns_resolver.erl

@@ -18,7 +18,7 @@
 %% gen_server callbacks
 -export([init/1, handle_call/3, handle_cast/2, handle_info/2, terminate/2, code_change/3]).
 
--export([forward/6]).
+-export([forward/5]).
 
 -define(SERVER, ?MODULE).
 
@@ -31,8 +31,8 @@
 %%% API
 %%%===================================================================
 
-forward(Pid, ReceiverPid, Ref, TargetIp, TargetPort, Request) ->
+forward(Pid, ReceiverPid, TargetIp, TargetPort, Request) ->
-    gen_server:cast(Pid, {forward, ReceiverPid, Ref, TargetIp, TargetPort, Request}).
+    gen_server:cast(Pid, {forward, ReceiverPid, TargetIp, TargetPort, Request}).
 
 %% @doc Spawns the server and registers the local name (unique)
 -spec(start_link(Args :: list()) ->
@@ -75,11 +75,11 @@ handle_call(_Request, _From, State = #state{}) ->
     {noreply, NewState :: #state{}} |
     {noreply, NewState :: #state{}, timeout() | hibernate} |
     {stop, Reason :: term(), NewState :: #state{}}).
-handle_cast({forward, ReceiverPid, Ref, TargetIp, TargetPort, Request}, State = #state{socket = Socket, tid = Tid}) ->
+handle_cast({forward, ReceiverPid, TargetIp, TargetPort, Request}, State = #state{socket = Socket, tid = Tid}) ->
     case dns:decode_message(Request) of
         #dns_message{id = TxId, questions = [#dns_query{name = QName}|_]} ->
             ok = gen_udp:send(Socket, TargetIp, TargetPort, Request),
-            ok = ets:insert(Tid, {{TxId, TargetIp, TargetPort, QName}, {Ref, ReceiverPid}});
+            ok = ets:insert(Tid, {{TxId, TargetIp, TargetPort, QName}, ReceiverPid});
         _ ->
             ok
     end,
@@ -96,8 +96,13 @@ handle_info({udp, Socket, TargetIp, TargetPort, Resp}, State = #state{tid = Tid,
         #dns_message{id = TxId, questions = [#dns_query{name = QName}|_]} ->
             Key = {TxId, TargetIp, TargetPort, QName},
             case ets:take(Tid, Key) of
-                [{_, {Ref, ReceiverPid}}] ->
+                [{_, ReceiverPid}] ->
-                    ReceiverPid ! {xyz, Ref, Resp};
+                    case is_process_alive(ReceiverPid) of
+                        true ->
+                            ReceiverPid ! {dns_resolver_reply, Resp};
+                        false ->
+                            ok
+                    end;
                 [] ->
                     ok
             end;

apps/dns_proxy/src/dns_server.erl

@@ -9,14 +9,6 @@ start_link() ->
 init() ->
     dns_cache:init(),
     %dns_zone_loader:load("priv/local.zone"),
-
-    %% 配置上游 DNS
-    Upstreams = [
-        {{8,8,8,8}, 53},
-        {{1,1,1,1}, 53}
-    ],
-    dns_socket_pool:start_link(Upstreams),
-
     {ok, Sock} = gen_udp:open(?LISTEN_PORT, [binary, {active, true}]),
     io:format("DNS Forwarder started on UDP port ~p~n", [?LISTEN_PORT]),
     loop(Sock).
@@ -25,6 +17,6 @@ loop(Sock) ->
     receive
         {udp, Sock, Ip, Port, Packet} ->
             Res = dns_handler_sup:start_handler(Sock, Ip, Port, Packet),
-            lager:debug("ip: ~p, get a packet: ~p, handler res: ~p", [{Ip, Port}, Packet, Res]),
+            lager:debug("[dns_server] ip: ~p, get a packet: ~p, handler res: ~p", [{Ip, Port}, Packet, Res]),
             loop(Sock)
     end.

apps/dns_proxy/src/dns_socket_pool.erl

@@ -1,26 +0,0 @@
--module(dns_socket_pool).
--behaviour(gen_server).
-
--export([start_link/1, get_socket/0]).
--export([init/1, handle_call/3]).
-
--record(state, {sockets=[]}).
-
-start_link(Ups) ->
-    gen_server:start_link({local, ?MODULE}, ?MODULE, Ups, []).
-
-get_socket() ->
-    gen_server:call(?MODULE, get).
-
-init(Upstreams) ->
-    %% 为多个上游 DNS 建 socket
-    Sockets = lists:map(fun({IP, Port}) ->
-        {ok, Sock} = gen_udp:open(0, [binary, {active, false}]),
-        {Sock, {IP, Port}}
-                        end, Upstreams),
-    {ok, #state{sockets=Sockets}}.
-
-handle_call(get, _From, State=#state{sockets=Socks}) ->
-    %% 简单 round-robin
-    [H|T] = Socks,
-    {reply, H, State#state{sockets=T ++ [H]}}.