本文来自：瑞仙的Erlang开发博客

原文链接：http://blog.csdn.net/zhongruixian/article/details/39528765

一、前言

关于cer/pem证书转换，网上很多资料，我这就不说了，

网上有PHP实现的Push Notification，可以参考，

为了更好的做PUSH服务定制，我这里以Erlang（gen_server）实现iOS Push Notification

二、协议

1、协议分析

表1

表2

表3

2、协议数据打包实现

注意：网络字节序要有大端序

pack_frame(Cmd, Data) ->
    Len = byte_size(Data),
    <<Cmd:8, Len:16/big, Data/binary>>.

pack_frames(Frames) ->
    FramesBin = list_to_binary(Frames),
    FrameLen = byte_size(FramesBin),
    <<2:8/big, FrameLen:32/big, FramesBin/binary>>.

%% 16进制字符串转binary
hex_to_bin(Data) when is_binary(Data) ->
    hex_to_bin(binary_to_list(Data));
hex_to_bin(Data) ->
    hex_to_bin(Data, []).

hex_to_bin([H1, H2 | T], Rt) ->
    D1 = hex_to_oct(H1),
    D2 = hex_to_oct(H2),
    D = D1 bsl 4 + D2,
    hex_to_bin(T, [<<D:8>> | Rt]);
hex_to_bin([], Rt) ->
    list_to_binary(lists:reverse(Rt)).

hex_to_oct(N) when N >= 48, N =< 58 ->
	N - 48;
hex_to_oct(N) when N >= 65, N =< 70 ->
	N - 55;
hex_to_oct(N) when N >= 97, N =< 102 ->
	N - 87.

三、PUSH实现过程

1、SSL启动

ssl:start()

2、SSL连接（gen_server代码片段）

-record(state, { ssl_socket }).

start_link() ->
    gen_server:start_link({local, push}, ?MODULE, [], []).

init([]) ->
    {ok, #state{}}.

handle_info(connect, State) ->
    try
        TcpOptions = [binary, {packet, 0}, {nodelay, true}, {delay_send, true}, {exit_on_close, false}],
        SslOptions = [ {password, "1234"} ,{keyfile, "./dev_msttd_aps.pem"} ,{certfile, "./dev_msttd_aps.pem"},

        Options = TcpOptions ++ SslOptions,
        case ssl:connect("gateway.sandbox.push.apple.com", 2195, Options, 30000) of
            {ok, Socket} ->
                ?INFO("~npush connect OK:~n~w", [Socket]),
                {noreply, State#state{ssl_socket = Socket}};
            {error, Error} ->
                ?INFO("~w", [Error]),
                {noreply, State}
        end;
        catch T : X ->
            ?INFO("~p:~p~n~p", [T, X, erlang:get_stacktrace()]),
            {noreply, State}
    end;

3、向一个设备PUSH消息（gen_server代码片段）

handle_info({send, DeviceToken1}, State) ->
    try
        Time = util:unixtime(),
        DeviceToken = hex_to_bin(DeviceToken1),
        Payload = <<"{\"aps\":{\"alert\":\"《萌獸堂》萌獸等你來戰！\",\"sound\":\"default\"}}">>,
        PayloadLen = byte_size(Payload),
        Frame1 = pack_frame(1, DeviceToken),
        Frame2 = pack_frame(2, Payload),
        Frame3 = pack_frame(3, <<Time:32/big>>),
        Frame4 = pack_frame(4, <<Time:32/big>>),
        Frame5 = pack_frame(5, <<10:8/big>>),
        Data = pack_frames([Frame1, Frame2, Frame3, Frame4, Frame5]),
        case ssl:send(State#state.ssl_socket, Data) of
            ok -> ?INFO("send ok (~s)", [DeviceToken1]);
            Error -> ?INFO("send error:~p", [Error])
        end
        catch T : X ->
            ?INFO("~p:~p~n~p", [T, X, erlang:get_stacktrace()])
    end,
    {noreply, State};

4、错误处理（gen_server代码片段）

handle_info({ssl, _,<<8:8, StateCode:8, Id:32/big>>}, State) ->
    %% TODO: 出错啦，根据StateCode来具体处理吧
    ?INFO("Error: ~w - ~w", [StateCode, Id]),
    {noreply, State};

四、使用实例

push ! connect.

push ! {send, "8333801EBED044241D35C182F9F5CED47231D56A398AA1991060E3086699FE9F"}.