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Erlang TCP服务器/客户端发送消息

tcperlangclient-servergen-tcp
3
我正在编写一个简单的服务器，它将与连接并相互交流的客户端一起工作，其中服务器充当中介。
设置如下：
- 服务器开始 - 2个客户端连接到服务器 - 客户端1/2发送带有其唯一ID（原子）的消息 - 服务器将此ID与Socket PID保存在一起 - 客户端1发送{send_to_id，client2id，Message} - 服务器向客户端2发送消息
但是，这对我不起作用，我得到了一个function_clause错误。
所以，基本上我想使用tcp_send向客户端发送消息，而不必使客户端成为“服务器”，只需使用recv。 这可能吗？
服务器代码：
-export([start/1]).

-define(TCP_OPTIONS, [binary, {packet, 2}, {active, false}, {reuseaddr, true}]).
-define(PORT, 8080). 

-spec start(Port) -> pid() when
      Port::integer().
start(Port) ->
    process_flag(trap_exit, true),
    ClientDict = dict:new(),
    GamesDict = dict:new(),
    HandlerPID = spawn_link(fun() -> handler(ClientDict, GamesDict) end),
    imup_listener:listen(Port, HandlerPID).





%%------------------------------
% Internal Functions
%%------------------------------

handler(Clients, Games) ->
    receive
    {insert_client, Socket, Alias} ->
        TmpClients = dict:append(Socket, Alias, Clients),
        TmpClients2 = dict:append(Alias, Socket, TmpClients),
        handler(TmpClients2, Games);
    {get_client_id, ReceiverPID, ClientPID} ->
        {ok , CID} = dict:find(ClientPID, Clients),
        ReceiverPID ! {id, CID},
        handler(Clients, Games);
    {get_client_pid, ReceiverPID, ClientID} ->
        {ok, CPID} = dict:find(ClientID, Clients),
        ReceiverPID ! {pid, CPID},
        handler(Clients, Games);
    {host_game, HostID, GameID} ->
        TmpGames = dict:append_list(GameID, [HostID], Games),
        handler(Clients, TmpGames);
    {add_player, PlayerID, GameID} ->
        TmpGames = dict:append_list(GameID, [PlayerID], Games),
        handler(Clients, TmpGames);
    {get_host, ReceiverPID, GameID} ->
        {ok, [HID|T]} = dict:find(GameID, Games),
        {ok, HPID} = dict:find(HID, Clients),
        ReceiverPID ! {host_is, HID, HPID},
        handler(Clients, Games);

    _ ->
        {error, "I don't know what you want from me :("}
    end.

监听器代码：

-export([listen/2]).

-define(TCP_OPTIONS, [binary, {packet, 2}, {active, false}, {reuseaddr, true}]).

listen(Port, HandlerPID) ->
    {ok, LSocket} = gen_tcp:listen(Port, ?TCP_OPTIONS),
    spawn_link(fun() -> accept(LSocket, HandlerPID) end),
    LSocket.




% Wait for incoming connections and spawn a process that will process incoming packets.
accept(LSocket, HandlerPID) ->
    {ok, Socket} = gen_tcp:accept(LSocket),
    Pid = spawn(fun() ->
            io:format("Connection accepted ~n", []),
            %%DictPID ! {insert, Socket, Socket},
            loop(Socket, HandlerPID)
        end),
    gen_tcp:controlling_process(Socket, Pid),
    accept(LSocket, HandlerPID).



% Echo back whatever data we receive on Socket
loop(Sock, HandlerPID) ->
    inet:setopts(Sock, [{active, once}]),
    receive
    {tcp, Socket, Data} ->
        io:format("Got packet: ~p == ", [Data]),

        FormatedData = process_data(Socket, Data, HandlerPID),
        io:format("~p~n", [FormatedData]),
        convey_message(Socket, FormatedData),

        loop(Socket, HandlerPID);
    {tcp_closed, Socket} ->
        io:format("Socket ~p closed~n", [Socket]);
    {tcp_error, Socket, Reason} ->
        io:format("Error on socket ~p reason: ~p~n", [Socket, Reason])
    end.




%%------------------------------
% Internal Functions
%%------------------------------


-spec process_data(S, D, P) -> term() when
      S::port(),
      D::binary(),
      P::pid().
process_data(Socket, Data, HandlerPID) when is_binary(Data) ->
    case binary_to_term(Data) of
    {send_host, GameID, Msg} ->
        HandlerPID ! {get_host, self(), GameID},
        receive
        {host_is, _HID, HSOCK} ->
            HSOCK;
        _ ->
            {error, nohost}
        end,
        Msg;
    {send_all, GameID, Msg} ->
        Msg;
    {send_to_id, ReceiverID, Msg} ->
        HandlerPID ! {get_client_pid, self(), ReceiverID},
        receive
           {pid, SockPID} ->
            gen_tcp:send(SockPID, term_to_binary(Msg));
        _ ->
            {error, noid}
        end,
        term_to_binary({ok, delivered});
    {host_game, GameID} ->
        GameID;
    {join_game, GameID} ->
        GameID;
    {start_game, GameID} ->
        GameID;
    {enter, SenderID} ->
        HandlerPID ! {insert_client, Socket, SenderID};
    Dat ->
        Dat
    end;
process_data(Socket, Data, DictPID) ->
    Data.


convey_message(Socket, Data) when is_binary(Data) ->
    gen_tcp:send(Socket, Data);
convey_message(Socket, Data) ->
    gen_tcp:send(Socket, term_to_binary(Data)).

客户端代码：

-export([connect/1, connect/2, disconnect/1, send/2, recv/1]).

connect(PortNo) ->
    {ok, Socket} = gen_tcp:connect("localhost", PortNo, [{active, false}, {packet, 2}]),
    spawn(fun() -> recv(Socket) end),
    Socket.

connect(IP, PortNo) ->
    {ok, Socket} = gen_tcp:connect(IP, PortNo, [{active, false}, {packet, 2}]),
    spawn(fun() -> recv(Socket) end),
    Socket.


send(Socket, Message) ->
    BinMsg = term_to_binary(Message),
    gen_tcp:send(Socket, BinMsg).
%%    {ok, A} = gen_tcp:recv(Socket, 0),
    %%A.

recv(Socket) ->
    {ok, A} = gen_tcp:recv(Socket, 0),
    io:format("Received: ~p~n", [A]),
    recv(Socket).


disconnect(Socket) ->
    gen_tcp:close(Socket).

你认为我需要重新编写所有内容，还是我的想法有些可行呢？感谢提前回答！编辑:添加了测试运行。
Eshell V5.8.5  (abort with ^G)
1> imup_server:start(1234).
#Port<0.669>
2> Socket1 = imup_client:connect(1234).
Connection accepted 
#Port<0.681>
3> Socket2 = imup_client:connect(1234).
Connection accepted 
#Port<0.683>
4> imup_client:send(Socket1, {enter, cOne}).
ok
Got packet: <<131,104,2,100,0,5,101,110,116,101,114,100,0,4,99,79,110,101>> == {insert_client,#Port<0.682>,cOne}
Received: [131,104,3,100,0,13,105,110,115,101,114,116,95,99,108,105,101,110,
           116,102,100,0,13,110,111,110,111,100,101,64,110,111,104,111,115,
           116,0,0,2,170,0,100,0,4,99,79,110,101]
5> imup_client:send(Socket2, {enter, cTwo}).
ok
Got packet: <<131,104,2,100,0,5,101,110,116,101,114,100,0,4,99,84,119,111>> == {insert_client,#Port<0.684>,cTwo}
Received: [131,104,3,100,0,13,105,110,115,101,114,116,95,99,108,105,101,110,
           116,102,100,0,13,110,111,110,111,100,101,64,110,111,104,111,115,
           116,0,0,2,172,0,100,0,4,99,84,119,111]
6> imup_client:send(Socket1, {send_to_id, cTwo, hello}).
ok
Got packet: <<131,104,3,100,0,10,115,101,110,100,95,116,111,95,105,100,100,0,4,
              99,84,119,111,100,0,5,104,101,108,108,111>> == 7> 
=ERROR REPORT==== 5-May-2013::23:25:49 ===
Error in process <0.39.0> with exit value: {function_clause,[{gen_tcp,send,[[#Port<0.684>],<<9 bytes>>]},{imup_listener,process_data,3},{imup_listener,loop,2}]}


=ERROR REPORT==== 5-May-2013::23:25:49 ===
Error in process <0.40.0> with exit value: {{badmatch,{error,closed}},[{imup_client,recv,1}]}
为了调试这个问题，能够看到错误信息会很有帮助... 我的经验是，函数子句通常只是拼写错误或类似问题。 - Martin Kristiansen
当然！忘记添加了，现在已经添加到底部了。 - Klesken
1个回答
4
当使用参数[#Port<0.684>]和<<9 bytes>>调用gen_tcp:send时，你会遇到一个function_clause错误。第一个参数是包含“port”的列表（在这种情况下为socket），但它应该只是端口号。
如果我理解代码正确的话，发生这种情况是因为你正在使用dict:append将sockets放入字典中，这会导致字典的值成为列表。除非你确实需要为每个客户端存储多个sockets或者反之，否则可能更适合使用dict:store方法。
谢谢，我可能一直都瞎了，因为我甚至测试了字典函数，现在我可以接收消息了。然而又出现了另一个问题，当服务器接收时它是二进制的，但是当客户端接收时它变成了列表。我不知道为什么会发生这种情况，因为我在发送时使用了相同的term_to_binary/binary_to_term。有任何想法吗？ - Klesken
3
如果想以二进制数据接收消息，您的客户端应该以二进制形式打开Socket。在打开客户端tcp Socket时，将原子binary添加到选项列表中： gen_tcp:connect(IP, PortNo, [binary, {active, false}, {packet, 2}])。 - David Wickstrom
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