简化代码逻辑

apps/sdlan/src/net/arp_packet.erl

@@ -4,7 +4,7 @@
 -module(arp_packet).
 
 -export([parse/1, marshal/1, is_broadcast_mac/1, arp_request/3, arp_response/3]).
--export([opcode/1]).
+-export([opcode/1, target_ip/1]).
 
 -define(ETHERNET, 16#0001).
 -define(IPV4,     16#0800).
@@ -26,6 +26,20 @@
     target_ip
 }).
 
+-type arp_packet() :: #arp_packet{
+    hardware_type :: integer(),
+    protocol_type :: integer(),
+    hardware_size :: integer(),
+    protocol_size :: integer(),
+    opcode :: atom() | integer(),
+    sender_mac :: binary(),
+    sender_ip :: integer(),
+    target_mac :: binary(),
+    target_ip :: integer()
+}.
+
+-export_type([arp_packet/0]).
+
 %%--------------------------------------------------------------------
 %% Parsing
 %%--------------------------------------------------------------------
@@ -70,6 +84,10 @@ parse(Bin) when is_binary(Bin) ->
 opcode(#arp_packet{opcode = Opcode}) ->
     Opcode.
 
+-spec target_ip(Arp_packet :: #arp_packet{}) -> TargetIp :: integer().
+target_ip(#arp_packet{target_ip = TargetIp}) ->
+    TargetIp.
+
 %%--------------------------------------------------------------------
 %% Marshal
 %%--------------------------------------------------------------------

apps/sdlan/src/sdlan_network.erl

@@ -7,6 +7,8 @@
 %%% Created : 27. 3月 2024 15:13
 %%%-------------------------------------------------------------------
 -module(sdlan_network).
+-feature(maybe_expr, enable).
+
 -author("anlicheng").
 -include("sdlan.hrl").
 -include("sdlan_pb.hrl").
@@ -340,46 +342,34 @@ handle_cast({forward, Sock, SrcMac, DstMac, Packet}, State = #state{network_id =
     case sdlan_util:is_broadcast_mac(DstMac) orelse sdlan_util:is_multicast_mac(DstMac) of
         true ->
             %% 解析Packet是不是arp请求
-            case layer_packet:parse(Packet) of
+            case maybe_arp_request(Packet) of
-                {ok, LayerPacket} ->
+                {ok, ArpRequestPkt} ->
-                    case layer_packet:packet_type(LayerPacket) of
+                    TargetIp = arp_packet:target_ip(ArpRequestPkt),
-                        arp ->
+                    %% 通过ip查找到对应的Endpoint
-                            case arp_packet:parse(layer_packet:payload(LayerPacket)) of
-                                {ok, ArpPacket} ->
 
-                                    case arp_packet:opcode(ArpPacket) of
+                    TargetMac = <<>>,
-                                        request ->
+                    ArpResponse = arp_packet:marshal(arp_packet:arp_response(ArpRequestPkt, TargetMac, TargetIp)),
-                                            %% TODO
+                    #endpoint{hole = #hole{peer = {NatIp, NatPort}}} = maps:get(SrcMac, UsedMap),
-                                            Mac = <<>>,
+                    gen_udp:send(Sock, NatIp, NatPort, ArpResponse);
-                                            Ip = 12,
-                                            ArpResponse = arp_packet:marshal(arp_packet:arp_response(ArpPacket, Mac, Ip)),
 
-                                            #endpoint{hole = #hole{peer = {NatIp, NatPort}}} = maps:get(SrcMac, UsedMap),
+                error ->
-                                            gen_udp:send(Sock, NatIp, NatPort, ArpResponse)
+                    PacketBytes = byte_size(Packet),
-                                    end;
+                    %% 消息广播
+                    maps:foreach(fun(Mac, #endpoint{hole = Hole}) ->
+                        case {Mac =/= SrcMac, Hole} of
+                            {true, #hole{peer = {NatIp, NatPort}}} ->
+                                gen_udp:send(Sock, NatIp, NatPort, Packet);
+                            _ ->
+                                ok
+                        end
+                                 end, UsedMap),
 
-                                _ ->
+                    %% client和stun之间必须有心跳机制保持nat映射可用，并且通过服务转发的udp包肯定可以到达对端的nat
-                                    ok
+                    lager:debug("[sdlan_network] broadcast data networkd_id: ~p, src_mac: ~p, dst_mac: ~p",
-                            end
+                        [NetworkId, sdlan_util:format_mac(SrcMac), sdlan_util:format_mac(DstMac)]),
-                    end
-            end,
 
-            PacketBytes = byte_size(Packet),
+                    {noreply, State#state{forward_bytes = ForwardBytes + PacketBytes}}
-            %% 消息广播
+            end;
-            maps:foreach(fun(Mac, #endpoint{hole = Hole}) ->
-                case {Mac =/= SrcMac, Hole} of
-                    {true, #hole{peer = {NatIp, NatPort}}} ->
-                        gen_udp:send(Sock, NatIp, NatPort, Packet);
-                    _ ->
-                        ok
-                end
-                         end, UsedMap),
-
-            %% client和stun之间必须有心跳机制保持nat映射可用，并且通过服务转发的udp包肯定可以到达对端的nat
-            lager:debug("[sdlan_network] broadcast data networkd_id: ~p, src_mac: ~p, dst_mac: ~p",
-                [NetworkId, sdlan_util:format_mac(SrcMac), sdlan_util:format_mac(DstMac)]),
-
-            {noreply, State#state{forward_bytes = ForwardBytes + PacketBytes}};
         false ->
             lager:debug("[sdlan_network] networkd_id: ~p, src_mac: ~p, dst_mac: ~p, forward discard 1",
                 [NetworkId, sdlan_util:format_mac(SrcMac), sdlan_util:format_mac(DstMac)]),
@@ -474,6 +464,19 @@ code_change(_OldVsn, State = #state{}, _Extra) ->
 %%% Internal functions
 %%%===================================================================
 
+-spec maybe_arp_request(Packet :: binary()) -> error | {ok, ArpPkt :: arp_packet:arp_packet()}.
+maybe_arp_request(Packet) when is_binary(Packet) ->
+    maybe
+        {ok, LayerPacket} ?= layer_packet:parse(Packet),
+        arp ?= layer_packet:packet_type(LayerPacket),
+        {ok, ArpPacket} ?= arp_packet:parse(layer_packet:payload(LayerPacket)),
+        request ?= arp_packet:opcode(ArpPacket),
+        {ok, ArpPacket}
+    else
+        _ ->
+            error
+    end.
+
 -spec limiting_check(ThrottleKey :: any()) -> pass | denied.
 limiting_check(ThrottleKey) ->
     case throttle:check(sdlan_network, ThrottleKey) of