简化dns的解析逻辑
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@ -9,18 +9,11 @@
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-module(dns_handler).
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-author("anlicheng").
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-behaviour(gen_server).
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-include_lib("dns_erlang/include/dns.hrl").
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-include_lib("pkt/include/pkt.hrl").
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-include("dns_proxy.hrl").
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%% API
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-export([start_link/0]).
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%% gen_server callbacks
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-export([init/1, handle_call/3, handle_cast/2, handle_info/2, terminate/2, code_change/3]).
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-export([handle_ip_packet/5]).
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-export([handle/4]).
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-define(SERVER, ?MODULE).
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-define(RESOLVER_POOL, dns_resolver_pool).
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@ -35,44 +28,7 @@
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%%% API
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%%%===================================================================
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start_link() ->
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gen_server:start_link(?MODULE, [], []).
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handle_ip_packet(Pid, Sock, SrcIp, SrcPort, Packet) when is_pid(Pid) ->
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gen_server:cast(Pid, {handle_ip_packet, Sock, SrcIp, SrcPort, Packet}).
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%%%===================================================================
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%%% gen_server callbacks
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%%%===================================================================
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%% @private
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%% @doc Initializes the server
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-spec(init(Args :: term()) ->
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{ok, State :: #state{}} | {ok, State :: #state{}, timeout() | hibernate} |
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{stop, Reason :: term()} | ignore).
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init([]) ->
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{ok, #state{}}.
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%% @private
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%% @doc Handling call messages
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-spec(handle_call(Request :: term(), From :: {pid(), Tag :: term()},
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State :: #state{}) ->
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{reply, Reply :: term(), NewState :: #state{}} |
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{reply, Reply :: term(), NewState :: #state{}, timeout() | hibernate} |
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{noreply, NewState :: #state{}} |
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{noreply, NewState :: #state{}, timeout() | hibernate} |
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{stop, Reason :: term(), Reply :: term(), NewState :: #state{}} |
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{stop, Reason :: term(), NewState :: #state{}}).
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handle_call(_Request, _From, State = #state{}) ->
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{reply, ok, State}.
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%% @private
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%% @doc Handling cast messages
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-spec(handle_cast(Request :: term(), State :: #state{}) ->
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{noreply, NewState :: #state{}} |
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{noreply, NewState :: #state{}, timeout() | hibernate} |
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{stop, Reason :: term(), NewState :: #state{}}).
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handle_cast({handle_ip_packet, Sock, SrcIp, SrcPort, IpPacket}, State) ->
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handle(Sock, SrcIp, SrcPort, IpPacket) ->
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{#ipv4{saddr = ReqSAddr, daddr = ReqDAddr, p = Protocol}, ReqIpPayload} = pkt:ipv4(IpPacket),
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case Protocol =:= ?UDP_PROTOCOL of
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true ->
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@ -86,35 +42,7 @@ handle_cast({handle_ip_packet, Sock, SrcIp, SrcPort, IpPacket}, State) ->
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end;
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false ->
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logger:notice("[dns_handler] resolver invalid protocol: ~p", [Protocol])
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end,
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{stop, normal, State}.
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%% @private
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%% @doc Handling all non call/cast messages
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-spec(handle_info(Info :: timeout() | term(), State :: #state{}) ->
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{noreply, NewState :: #state{}} |
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{noreply, NewState :: #state{}, timeout() | hibernate} |
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{stop, Reason :: term(), NewState :: #state{}}).
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handle_info(_Info, State) ->
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{noreply, State}.
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%% @private
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%% @doc This function is called by a gen_server when it is about to
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%% terminate. It should be the opposite of Module:init/1 and do any
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%% necessary cleaning up. When it returns, the gen_server terminates
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%% with Reason. The return value is ignored.
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-spec(terminate(Reason :: (normal | shutdown | {shutdown, term()} | term()),
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State :: #state{}) -> term()).
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terminate(_Reason, _State = #state{}) ->
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ok.
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%% @private
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%% @doc Convert process state when code is changed
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-spec(code_change(OldVsn :: term() | {down, term()}, State :: #state{},
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Extra :: term()) ->
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{ok, NewState :: #state{}} | {error, Reason :: term()}).
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code_change(_OldVsn, State = #state{}, _Extra) ->
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{ok, State}.
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end.
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%%%===================================================================
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%%% Internal functions
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@ -162,11 +90,8 @@ resolver0(Packet, QueryMsg = #dns_message{qc = 1, questions = [Question = #dns_q
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RespMsg = build_response(QueryMsg, Cache),
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{ok, dns:encode_message(RespMsg)};
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miss ->
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Ref = make_ref(),
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forward_to_upstream(Ref, Packet, QueryMsg),
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logger:debug("[dns_handler] cache is miss, forward_to_upstream"),
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receive
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{dns_resolver_reply, Ref, Resp} ->
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case forward_to_upstream(Packet, QueryMsg) of
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{ok, Resp} ->
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case dns:decode_message(Resp) of
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RespMsg = #dns_message{answers = Answers} ->
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logger:debug("[dns_handler] get a response answers: ~p", [Answers]),
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@ -175,10 +100,10 @@ resolver0(Packet, QueryMsg = #dns_message{qc = 1, questions = [Question = #dns_q
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Error ->
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logger:debug("[dns_handler] parse reply get error: ~p", [Error]),
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{ok, EmptyDnsResp}
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end
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after 5000 ->
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logger:debug("[dns_handler] forward_to_upstream timeout"),
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{ok, EmptyDnsResp}
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end;
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{error, Reason} ->
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logger:debug("[dns_handler] parse reply get error: ~p", [Reason]),
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{ok, EmptyDnsResp}
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end
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end
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end
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@ -187,11 +112,6 @@ resolver0(_, Error) ->
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logger:warning("[dns_handler] decode dns_query get error: ~p", [Error]),
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{error, Error}.
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-spec forward_to_upstream(Ref :: reference(), Request :: binary(), QueryMsg :: #dns_message{}) -> no_return().
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forward_to_upstream(Ref, Request, QueryMsg) ->
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ReceiverPid = self(),
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poolboy:transaction(?RESOLVER_POOL, fun(Pid) -> dns_resolver:forward(Pid, ReceiverPid, Ref, Request, QueryMsg) end).
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-spec build_response(QueryMsg :: #dns_message{}, Dns_cache :: #dns_cache{}) -> RespMsg :: #dns_message{}.
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build_response(QueryMsg, #dns_cache{expire_at = ExpireAt, answers = Answers, authority = Authority, additional = Additional, rc = RCode, flags = #{aa := AA}}) ->
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Now = os:system_time(second),
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@ -261,3 +181,23 @@ build_ip_packet(SAddr, DAddr, SPort, DPort, UdpPayload) when is_integer(SPort),
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IpHeader = pkt:ipv4(IpPacket0#ipv4{sum = IpCheckSum}),
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<<IpHeader/binary, IpPayload/binary>>.
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-spec forward_to_upstream(Request :: binary(), QueryMsg :: #dns_message{}) -> no_return().
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forward_to_upstream(Request, #dns_message{id = TxId, questions = [#dns_query{name = QName, type = QType, class = QClass}|_]}) ->
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{ok, {DnsIp, DnsPort}} = application:get_env(sdlan, public_dns_server),
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{ok, Socket} = gen_udp:open(0, [binary, {active, true}]),
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ok = gen_udp:send(Socket, DnsIp, DnsPort, Request),
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logger:debug("[dns_resolver] send to: ~p, packet: ~p", [{DnsIp, DnsPort}, Request]),
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receive
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{udp, Socket, DnsIp, DnsPort, Resp} ->
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try dns:decode_message(Resp) of
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#dns_message{id = TxId, questions = [#dns_query{name = QName, type = QType, class = QClass}|_]} ->
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{ok, Resp};
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_ ->
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{error, invalid_dns_response}
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catch error:Err ->
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{error, Err}
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end
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after 2000 ->
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{error, timeout}
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end.
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@ -14,11 +14,6 @@ loop(Sock) ->
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receive
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{udp, Sock, Ip, Port, Packet} ->
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logger:debug("[dns_server] ip: ~p, get a packet: ~p", [{Ip, Port}, Packet]),
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case dns_handler_sup:start_handler() of
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{ok, HandlerPid} ->
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dns_handler:handle_ip_packet(HandlerPid, Sock, Ip, Port, Packet);
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Error ->
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logger:debug("[dns_server] start handler get error: ~p", [Error])
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end,
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spawn(fun() -> dns_handler:handle(Sock, Ip, Port, Packet) end),
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loop(Sock)
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end.
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