lib_chan库学习

-module(lib_chan_cs).
%% 实现服务器端结构和机制的模块

-export([start_raw_server/4, start_raw_client/3]).
-export([stop/1]).
-export([children/1]).

%% 客户端调用，用来连接服务器
start_raw_client(Host, Port, PacketLength) ->
    gen_tcp:connect(Host, Port,
            [binary, {active, true}, {packet, PacketLength}]).

%%启动服务器
%%以给定端口创建名字，如果该端口已经注册则服务器已经启动
%%如果端口未注册，则新建进程启动服务器，如果成功启动，则注册端口为新建进程号
%%调用cold_start新建进程来启动服务器，需要传入当前进程以便能获取新建进程的消息
%%新建进程传回进程id以确保接收到的信息是由新建进程传回的。
start_raw_server(Port, Fun, Max, PacketLength) ->
    Name = port_name(Port),
    case whereis(Name) of
    undefined ->
        Self = self(),
        Pid = spawn_link(fun() ->
                 cold_start(Self,Port,Fun,Max,PacketLength)
                 end),
        receive
        {Pid, ok} ->
            register(Name, Pid),
            {ok, self()};
        {Pid, Error} ->
            Error
        end;
    _Pid ->
        {error, already_started}
    end.

stop(Port) when integer(Port) ->
    Name = port_name(Port),
    case whereis(Name) of
    undefined ->
        not_started;
    Pid ->
        exit(Pid, kill),
        (catch unregister(Name)),
        stopped
    end.


%%获取连接到某端口的socket
children(Port) when integer(Port) ->
    port_name(Port) ! {children, self()},
    receive
    {session_server, Reply} -> Reply
    end.


port_name(Port) when integer(Port) ->
    list_to_atom("portServer" ++ integer_to_list(Port)).

%%监听端口
%%开始新建进程接受客户端连接，如果接收到连接，则调用Fun(Socket)
%%如果一个进程已经接收了一个连接，则需要再次新建进程接收客户端连接
%%最多只能接受Max个连接，超过了后将不再新建进程接收客户端连接，直到有其他的连接结束
cold_start(Master, Port, Fun, Max, PacketLength) ->
    process_flag(trap_exit, true),
    %% io:format("Starting a port server on ~p...~n",[Port]),
    case gen_tcp:listen(Port, [binary,
                   %% {dontroute, true},
                   {nodelay,true},
                   {packet, PacketLength},
                   {reuseaddr, true}, 
                   {active, true}]) of
    {ok, Listen} ->
        %% io:format("Listening to:~p~n",[Listen]),
        Master ! {self(), ok},
        New = start_accept(Listen, Fun),
        %% Now we're ready to run
        socket_loop(Listen, New, [], Fun, Max);
    Error ->
        Master ! {self(), Error}
    end.


socket_loop(Listen, New, Active, Fun, Max) ->
    receive
    {istarted, New} ->
        Active1 = [New|Active],
        possibly_start_another(false,Listen,Active1,Fun,Max);
    {'EXIT', New, _Why} ->
        %% io:format("Child exit=~p~n",[Why]),
        possibly_start_another(false,Listen,Active,Fun,Max);
    {'EXIT', Pid, _Why} ->
        %% io:format("Child exit=~p~n",[Why]),
        Active1 = lists:delete(Pid, Active),
        possibly_start_another(New,Listen,Active1,Fun,Max);
    {children, From} ->
        From ! {session_server, Active},
        socket_loop(Listen,New,Active,Fun,Max);
    _Other ->
        socket_loop(Listen,New,Active,Fun,Max)
    end.


possibly_start_another(New, Listen, Active, Fun, Max) 
  when pid(New) ->
    socket_loop(Listen, New, Active, Fun, Max);
possibly_start_another(false, Listen, Active, Fun, Max) ->
    case length(Active) of
    N when N < Max ->
        New = start_accept(Listen, Fun),
        socket_loop(Listen, New, Active, Fun,Max);
    _ ->
        socket_loop(Listen, false, Active, Fun, Max)
    end.

start_accept(Listen, Fun) ->
    S = self(),
    spawn_link(fun() -> start_child(S, Listen, Fun) end).

start_child(Parent, Listen, Fun) ->
    case gen_tcp:accept(Listen) of
    {ok, Socket} ->
        Parent ! {istarted,self()},            % tell the controller
        inet:setopts(Socket, [{packet,4},
                  binary,
                  {nodelay,true},
                  {active, true}]), 
        %% before we activate socket
        %% io:format("running the child:~p Fun=~p~n", [Socket, Fun]),
        process_flag(trap_exit, true),
        case (catch Fun(Socket)) of
        {'EXIT', normal} ->
            true;
        {'EXIT', Why} ->
            io:format("Port process dies with exit:~p~n",[Why]),
            true;
        _ ->
            %% not an exit so everything's ok
            true
        end
    end.

%%验证模块
-module(lib_chan_auth).

-export([make_challenge/0, make_response/2, is_response_correct/3]).

make_challenge() ->
    random_string(25).

make_response(Challenge, Secret) ->
    lib_md5:string(Challenge ++ Secret).

is_response_correct(Challenge, Response, Secret) ->
    case lib_md5:string(Challenge ++ Secret) of
    Response -> true;
    _        -> false
    end.

%% random_string(N) -> a random string with N characters.

random_string(N) -> random_seed(), random_string(N, []).

random_string(0, D) -> D;
random_string(N, D) ->
    random_string(N-1, [random:uniform(26)-1+$a|D]).

random_seed() ->
    {_,_,X} = erlang:now(),
    {H,M,S} = time(),
    H1 = H * X rem 32767,
    M1 = M * X rem 32767,
    S1 = S * X rem 32767,
    put(random_seed, {H1,M1,S1}).

-module(lib_chan_mm).
%% TCP中转
%% 导入该模块的模块可以应用send发送信息，并接收{chan, self(), Term}形式的信息

-export([loop/2, send/2, close/1, controller/2, set_trace/2, trace_with_tag/2]).

send(Pid, Term)       -> Pid ! {send, Term}.
close(Pid)            -> Pid ! close.
controller(Pid, Pid1) -> Pid ! {setController, Pid1}.
set_trace(Pid, X)     -> Pid ! {trace, X}.
    
trace_with_tag(Pid, Tag) ->
    set_trace(Pid, {true, 
            fun(Msg) -> 
                io:format("MM:~p ~p~n",[Tag, Msg]) 
            end}).
    
loop(Socket, Pid) ->
    %% trace_with_tag(self(), trace),
    process_flag(trap_exit, true),
    loop1(Socket, Pid, false).

%%实现对TCP发送信息，接收信息的封装
loop1(Socket, Pid, Trace) ->
    receive
    {tcp, Socket, Bin} ->
        Term = binary_to_term(Bin),
        trace_it(Trace,{socketReceived, Term}),
        Pid ! {chan, self(), Term},
        loop1(Socket, Pid, Trace);
    {tcp_closed, Socket} ->  
        trace_it(Trace, socketClosed),
        Pid ! {chan_closed, self()};
    {'EXIT', Pid, Why} ->
        trace_it(Trace,{controllingProcessExit, Why}),
        gen_tcp:close(Socket);
    {setController, Pid1} ->
        trace_it(Trace, {changedController, Pid}),
        loop1(Socket, Pid1, Trace);
    {trace, Trace1} ->
        trace_it(Trace, {setTrace, Trace1}),
        loop1(Socket, Pid, Trace1);
    close ->
        trace_it(Trace, closedByClient),
        gen_tcp:close(Socket);
    {send, Term}  ->
        trace_it(Trace, {sendingMessage, Term}),
        gen_tcp:send(Socket, term_to_binary(Term)),
        loop1(Socket, Pid, Trace);
    UUg ->
        io:format("lib_chan_mm: protocol error:~p~n",[UUg]),
        loop1(Socket, Pid, Trace)
    end.
trace_it(false, _)     -> void;
trace_it({true, F}, M) -> F(M).

%%主要模块
-module(lib_chan).
-export([cast/2, start_server/0, start_server/1,
     connect/5, disconnect/1, rpc/2]).
-import(lists, [map/2, member/2, foreach/2]).
-import(lib_chan_mm, [send/2, close/1]).


start_server() ->
    case os:getenv("HOME") of
    false ->
        exit({ebadEnv, "HOME"});
    Home ->
        start_server(Home ++ "/.erlang_config/lib_chan.conf")
    end.

%%根据配置文件启动服务器
%%配置文件形如
%%{port, 2223}.
%%{service, chat, password,"AsDT67aQ",mfa,mod_chat_controller,start,[]}.
%% file:consult(ConfigFile)读取config文件
start_server(ConfigFile) ->
    io:format("lib_chan starting:~p~n",[ConfigFile]),
    case file:consult(ConfigFile) of
    {ok, ConfigData} ->
        io:format("ConfigData=~p~n",[ConfigData]),
        case check_terms(ConfigData) of
        [] ->
            start_server1(ConfigData);
        Errors ->
            exit({eDaemonConfig, Errors})
        end;
    {error, Why} ->
        exit({eDaemonConfig, Why})
    end.


check_terms(ConfigData) ->
    L = map(fun check_term/1, ConfigData),
    [X || {error, X} <- L].
            
check_term({port, P}) when is_integer(P)     -> ok;
check_term({service,_,password,_,mfa,_,_,_}) -> ok;
check_term(X) -> {error, {badTerm, X}}.

%%新建服务器进程并注册为lib_chan
start_server1(ConfigData) ->
    register(lib_chan, spawn(fun() -> start_server2(ConfigData) end)).


start_server2(ConfigData) ->
    %%从ConfigData中提取Port
    [Port] = [ P || {port,P} <- ConfigData],
    start_port_server(Port, ConfigData).

%%启动服务器，对每一个连接进入服务器的Socket调用start_port_instance(Socket,ConfigData)
start_port_server(Port, ConfigData) ->
    lib_chan_cs:start_raw_server(Port, 
                fun(Socket) -> 
                    start_port_instance(Socket, 
                                ConfigData) end,
                100,
                4).

start_port_instance(Socket, ConfigData) ->
    %% This is where the low-level connection is handled
    %% We must become a middle man
    %% But first we spawn a connection handler
    S = self(),
    Controller = spawn_link(fun() -> start_erl_port_server(S, ConfigData) end),
    lib_chan_mm:loop(Socket, Controller).

start_erl_port_server(MM, ConfigData) ->
    receive
    {chan, MM, {startService, Mod, ArgC}} ->
        case get_service_definition(Mod, ConfigData) of
        {yes, Pwd, MFA} ->
            case Pwd of
            none ->
                send(MM, ack),
                really_start(MM, ArgC, MFA);
            _ ->
                do_authentication(Pwd, MM, ArgC, MFA)
            end;
        no ->
            io:format("sending bad service~n"),
            send(MM, badService),
            close(MM)
        end;
    Any ->
        io:format("*** ErL port server got:~p ~p~n",[MM, Any]),
        exit({protocolViolation, Any})
    end.

%%服务器用do_authentication进行验证，验证成功才对socket真正启动服务器的服务
do_authentication(Pwd, MM, ArgC, MFA) ->
    %%生成25位随机码
    C = lib_chan_auth:make_challenge(),
    send(MM, {challenge, C}),
    receive
    {chan, MM, {response, R}} ->
        case lib_chan_auth:is_response_correct(C, R, Pwd) of
        true ->
            send(MM, ack),
            really_start(MM, ArgC, MFA);
        false ->
            send(MM, authFail),
            close(MM)
        end
    end.


%% MM is the middle man
%% Mod is the Module we want to execute ArgC and ArgS come from the client and
%% server respectively

really_start(MM, ArgC, {Mod, Func, ArgS}) ->
    %% authentication worked so now we're off
    case (catch apply(Mod,Func,[MM,ArgC,ArgS])) of
    {'EXIT', normal} ->
        true;
    {'EXIT', Why} ->
        io:format("server error:~p~n",[Why]);
    Why ->
        io:format("server error should die with exit(normal) was:~p~n",
              [Why])
    end.

%% get_service_definition(Name, ConfigData)
%%获取服务的配置信息
get_service_definition(Mod, [{service, Mod, password, Pwd, mfa, M, F, A}|_]) ->
    {yes, Pwd, {M, F, A}};
get_service_definition(Name, [_|T]) ->
    get_service_definition(Name, T);
get_service_definition(_, []) ->
    no.

%%客户端连接服务器，先连接再进行验证
connect(Host, Port, Service, Secret, ArgC) ->
    S = self(),
    MM = spawn(fun() -> connect(S, Host, Port) end),
    receive
    {MM, ok} ->
        case authenticate(MM, Service, Secret, ArgC) of
        ok    -> {ok, MM};
        Error -> Error
        end;
    {MM, Error} ->
        Error
    end.

connect(Parent, Host, Port) ->
    case lib_chan_cs:start_raw_client(Host, Port, 4) of
    {ok, Socket} ->
        Parent ! {self(), ok},
        lib_chan_mm:loop(Socket, Parent);
    Error ->
        Parent ! {self(),  Error}
    end.

authenticate(MM, Service, Secret, ArgC) ->
    send(MM, {startService, Service, ArgC}),
    %% we should get back a challenge or a ack or closed socket
    receive
    {chan, MM, ack} ->
        ok;
    {chan, MM, {challenge, C}} ->
        R = lib_chan_auth:make_response(C, Secret),
        send(MM, {response, R}),
        receive
        {chan, MM, ack} ->
            ok;
        {chan, MM, authFail} ->
            wait_close(MM),
            {error, authFail};
        Other ->
            {error, Other}
        end;
    {chan, MM, badService} ->
        wait_close(MM),
        {error, badService};
    Other ->
        {error, Other}
    end.

wait_close(MM) ->
    receive
    {chan_closed, MM} ->
        true
    after 5000 ->
        io:format("**error lib_chan~n"),
        true
    end.

disconnect(MM) -> close(MM).

rpc(MM, Q) ->
    send(MM, Q),
    receive
    {chan, MM, Reply} ->
        Reply
    end.

cast(MM, Q) ->
    send(MM, Q).

该功能的使用方法为：
服务器端：
-import(lib_chan_mm, [send/2, controller/2]).
启动服务器
lib_chan:start_server("D:\code\erlcode\socket_dist\test.conf").
chat.conf为服务器的配置，如
{port, 2223}.
{service, test, password,"AsDT67aQ",mfa,mod_test_controller,start,[]}.

新启进程来接收消息


客户端：
调用lib_chan:connect(Host, Port, chat, Pwd, []) 连接服务器
将会调用配置文件中的mod_test_controller:start
连接好后用lib_chan_mm:send(MM, Msg).来给服务器发消息

使用方法如下例

-module(test_server).
-import(lib_chan_mm, [send/2, controller/2]).

-compile(export_all).


start() ->
    start_server(),
    lib_chan:start_server("D:\code\erlcode\socket_dist\test.conf").

start_server() ->
    register(test_server, 
         spawn(fun() ->
               process_flag(trap_exit, true),
               Val= (catch server_loop([])),
               io:format("Server terminated with:~p~n",[Val])
           end)).


server_loop(L) ->
    receive
    {mm, Channel, Msg} ->
        io:format("test_server received Msg=~p~n",[{Channel,Msg}]);
    Msg ->
        io:format("Server received Msg=~p~n",
              [Msg]),
        server_loop(L)
    end.

-module(mod_test_controller).
-export([start/3]).
-import(lib_chan_mm, [send/2]).

start(MM, _, _) ->
    process_flag(trap_exit, true),
    io:format("mod_test_controller start...~p~n",[MM]),
    loop(MM).

loop(MM) ->
     receive
     {chan, MM, Msg} ->
         test_server ! {mm, MM, Msg},
         loop(MM);
     Other ->
         io:format("mod_test_controller unexpected message =~p (MM=~p)~n",
               [Other, MM]),
         loop(MM)
    end. 

-module(test_client).

-export([start/0, connect/4]).


start() -> 
    connect("localhost", 2223, "AsDT67aQ", "a test msg").

connect(Host, Port, Pwd, Msg) ->
    io:format("test_client connect host:~p~n",[Msg]),
    case lib_chan:connect(Host, Port, test, Pwd, []) of
    {error, _Why} ->
        io:format("test_client can not connected:~p~n",[Msg]);
    {ok, MM} ->
          io:format("test_client connected:~p~n",[Msg]),
          lib_chan_mm:send(MM, Msg)
end.