From 8e2e3a7f399fa74889bb22ca25297353d190842a Mon Sep 17 00:00:00 2001
From: anlicheng <244108715@qq.com>
Date: Thu, 4 Dec 2025 00:03:17 +0800
Subject: [PATCH] fix dns parser

---
 apps/dns_proxy/src/dns_handler.erl  | 27 ++++++++++++++++++---------
 apps/dns_proxy/src/dns_resolver.erl |  3 ++-
 config/sys.config                   |  2 +-
 3 files changed, 21 insertions(+), 11 deletions(-)

diff --git a/apps/dns_proxy/src/dns_handler.erl b/apps/dns_proxy/src/dns_handler.erl
index 3d32395..ccb4845 100644
--- a/apps/dns_proxy/src/dns_handler.erl
+++ b/apps/dns_proxy/src/dns_handler.erl
@@ -32,6 +32,7 @@
     src_ip,
     src_port,
     packet,
+    qname,
     dns_servers = []
 }).
 
@@ -93,8 +94,8 @@ handle_cast(handle, State = #state{socket = Sock, src_ip = SrcIp, src_port = Src
                     lager:debug("[dns_handler] cache is miss"),
                     forward_to_upstream(DnsIp, DnsPort, Packet, Msg),
                     %% 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}}
+                    erlang:start_timer(?UPSTREAM_TIMEOUT, self(), {trigger_next, Msg}),
+                    {noreply, State#state{dns_servers = RestDnsServers, qname = Qname}}
             end;
         Other ->
             lager:warning("[] decode msg get error: ~p", [Other]),
@@ -108,11 +109,11 @@ handle_cast(handle, State = #state{socket = Sock, src_ip = SrcIp, src_port = Src
     {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),
+handle_info({timeout, _, {trigger_next, Msg}}, State = #state{packet = Packet, dns_servers = [{DnsIp, DnsPort}|RestDnsServers]}) ->
+    forward_to_upstream(DnsIp, DnsPort, Packet, Msg),
+    erlang:start_timer(?UPSTREAM_TIMEOUT, self(), {trigger_next, Msg}),
     {noreply, State#state{dns_servers = RestDnsServers}};
-handle_info({timeout, _, trigger_next}, State = #state{dns_servers = []}) ->
+handle_info({timeout, _, {trigger_next, _}}, State = #state{dns_servers = []}) ->
     {stop, normal, State};
 
 handle_info({timeout, _, handler_max_ttl}, State) ->
@@ -120,8 +121,16 @@ handle_info({timeout, _, handler_max_ttl}, State) ->
     {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)),
+handle_info({dns_resolver_reply, Resp}, State = #state{socket = Sock, src_ip = SrcIp, src_port = SrcPort, qname = Qname}) ->
+    %% 尝试解析
+    case dns:decode_message(Resp) of
+        Msg = #dns_message{answers = Answers} ->
+            lager:debug("[dns_handler] get a resolver reply: ~p", [Msg]),
+            dns_cache:insert(Qname, Answers),
+            gen_udp:send(Sock, SrcIp, SrcPort, Resp);
+        Other ->
+            lager:debug("[dns_handler] parse reply get error: ~p", [Other])
+    end,
     {stop, normal, State}.
 
 %% @private
@@ -154,4 +163,4 @@ forward_to_upstream(TargetIp, TargetPort, Request, Msg) ->
 
 build_response(Req, RR) ->
     Msg = Req,
-    Msg#dns_message{answers=[RR], qr=true, aa=true}.
\ No newline at end of file
+    Msg#dns_message{answers = RR, qr = true, aa = true}.
\ No newline at end of file
diff --git a/apps/dns_proxy/src/dns_resolver.erl b/apps/dns_proxy/src/dns_resolver.erl
index 99239d7..d3ca382 100644
--- a/apps/dns_proxy/src/dns_resolver.erl
+++ b/apps/dns_proxy/src/dns_resolver.erl
@@ -77,10 +77,11 @@ handle_call(_Request, _From, State = #state{}) ->
     {noreply, NewState :: #state{}, timeout() | hibernate} |
     {stop, Reason :: term(), NewState :: #state{}}).
 handle_cast({forward, ReceiverPid, TargetIp, TargetPort, Request, #dns_message{id = TxId, questions = [#dns_query{name = QName}|_]}}, State = #state{socket = Socket, tid = Tid}) ->
+    lager:debug("[dns_resolver] forward request to: ~p", [{TargetIp, TargetPort}]),
     ok = gen_udp:send(Socket, TargetIp, TargetPort, Request),
 
     Key = {TxId, TargetIp, TargetPort, QName},
-    ok = ets:insert(Tid, {Key, ReceiverPid}),
+    true = ets:insert(Tid, {Key, ReceiverPid}),
 
     erlang:start_timer(?REQUEST_TTL, self(), {clean_ticker, Key}),
 
diff --git a/config/sys.config b/config/sys.config
index 6b8e9fc..aabdd38 100644
--- a/config/sys.config
+++ b/config/sys.config
@@ -3,7 +3,7 @@
 
     %% 公共的dns域名解析服务
     {public_dns_servers, [
-      {{8,8,8,8}, 53},
+      {{114, 114, 114, 114}, 53},
       {{8,8,8,8}, 53}
     ]},