module for websocket and example of usage

examples/websocket/websocket.erl

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+-module(websocket).
+
+% The MIT License (MIT)
+
+% Copyright (c) <year> <copyright holders>
+
+% Permission is hereby granted, free of charge, to any person obtaining a copy
+% of this software and associated documentation files (the "Software"), to deal
+% in the Software without restriction, including without limitation the rights
+% to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+% copies of the Software, and to permit persons to whom the Software is
+% furnished to do so, subject to the following conditions:
+
+% The above copyright notice and this permission notice shall be included in
+% all copies or substantial portions of the Software.
+
+% THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+% IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+% FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+% AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+% LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+% OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+% THE SOFTWARE.
+
+-export([start_link/0, ws_loop/4, loop/1]).
+
+start_link() ->
+    Loop = fun (Req) ->
+                       ?MODULE:loop(Req)
+           end,
+
+    mochiweb_http:start_link([
+                              {name,  client_access}, 
+                              {loop, Loop},
+                              {port, 8080}
+                             ]).
+
+ws_loop(Socket, Payload, Sid, WsVersion) ->
+    ReentryWs = mochiweb_websocket:reentry({?MODULE, ws_loop}),
+    io:format("Received data: ~p~n", [Payload]),
+    ReentryWs(Socket, Sid, WsVersion).
+
+loop(Req) ->
+    ReentryWs = mochiweb_websocket:reentry({?MODULE, ws_loop}),
+    WsVersion = mochiweb_websocket:upgrade_connection(Req),
+
+    ReplySocket = Req:get(socket),
+
+    ReentryWs(Req:get(socket), [], WsVersion).

src/mochiweb_websocket.erl

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+-module(mochiweb_websocket).
+-author('lukasz.lalik@zadane.pl').
+
+%% The MIT License (MIT)
+
+%% Copyright (c) 2012 Zadane.pl sp. z o.o.
+
+%% Permission is hereby granted, free of charge, to any person obtaining a copy
+%% of this software and associated documentation files (the "Software"), to deal
+%% in the Software without restriction, including without limitation the rights
+%% to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+%% copies of the Software, and to permit persons to whom the Software is
+%% furnished to do so, subject to the following conditions:
+
+%% The above copyright notice and this permission notice shall be included in
+%% all copies or substantial portions of the Software.
+
+%% THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+%% IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+%% FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+%% AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+%% LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+%% OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+%% THE SOFTWARE.
+
+%% @doc Websockets module for Mochiweb. Based on Misultin websockets module.
+
+-export([loop/4, upgrade_connection/1, request/4]).
+-export([after_response/4, reentry/1, send/3]).
+
+-define(REQUEST_RECV_TIMEOUT, 3000000).   %% timeout waiting for request line
+-define(HEADERS_RECV_TIMEOUT, 30000).    %% timeout waiting for headers
+
+-define(MAX_HEADERS, 1000).
+-define(DEFAULTS, [{name, ?MODULE},
+                   {port, 8888}]).
+
+loop(Socket, Body, State, WsVersion) ->
+    ok = mochiweb_socket:setopts(Socket, [{packet, 0}, {active, once}]),
+    proc_lib:hibernate(?MODULE, request, [Socket, Body, State, WsVersion]).
+
+upgrade_connection(Req) ->
+    % Headers for HYBI handshake
+    SecKey  = Req:get_header_value("sec-websocket-key"),
+    Sec1Key = Req:get_header_value("Sec-WebSocket-Key1"),
+    Sec2Key = Req:get_header_value("Sec-WebSocket-Key2"),
+    Origin = Req:get_header_value(origin),
+
+    if not (SecKey == undefined) ->
+          hybi_handshake(Req, SecKey);
+
+      (not (Sec1Key == undefined)) and (not (Sec2Key == undefined)) ->
+          Body = Req:recv(8),
+          hixie_handshake(Req, Sec1Key, Sec2Key, Body, Origin);
+
+       true ->
+          mochiweb_socket:close(Req:get(socket)),
+          exit(normal)
+    end.
+
+
+hybi_handshake(Req, SecKey) ->
+  Challenge = handshake_key(SecKey),
+  Req:respond({101, [{"Connection", "Upgrade"},
+                     {"Upgrade", "websocket"},
+                     {"Sec-Websocket-Accept", Challenge}], ""}),
+  hybi.
+
+hixie_handshake(Req, Key1, Key2, Body, Origin) ->
+  Ikey1 = [D || D <- Key1, $0 =< D, D =< $9],
+  Ikey2 = [D || D <- Key2, $0 =< D, D =< $9],
+  Blank1 = length([D || D <- Key1, D =:= 32]),
+  Blank2 = length([D || D <- Key2, D =:= 32]),
+  Part1 = erlang:list_to_integer(Ikey1) div Blank1,
+  Part2 = erlang:list_to_integer(Ikey2) div Blank2,
+  Ckey = <<Part1:4/big-unsigned-integer-unit:8, Part2:4/big-unsigned-integer-unit:8, Body/binary>>,
+  Challenge = erlang:md5(Ckey),
+
+  Location = lists:concat(["ws://", 
+                           Req:get_header_value("Host"),
+                           Req:get(path)]),
+
+  Req:respond({101, [{"Upgrade", "WebSocket"},
+                     {"Connection", "Upgrade"},
+                     {"Sec-WebSocket-Origin", Origin},
+                     {"Sec-WebSocket-Location", Location}],
+                    Challenge}),
+  hixie.
+
+
+
+send(Socket, Payload, hybi) ->
+    Len = payload_length(iolist_size(Payload)),
+    Data = <<1:1, 0:3, 1:4, 0:1, Len/bits, Payload/binary>>,
+    mochiweb_socket:send(Socket, Data);
+
+send(Socket, Payload, hixie) ->
+    Data = <<0, Payload/binary, 255>>,
+    mochiweb_socket:send(Socket, Data).
+
+request(Socket, Body, State, WsVersion) ->
+    receive
+        {tcp_closed, _} ->
+            mochiweb_socket:close(Socket),
+            exit(normal);
+        {ssl_closed, _} ->
+            mochiweb_socket:close(Socket),
+            exit(normal);
+        {tcp_error, _, _} ->
+            mochiweb_socket:close(Socket),
+            exit(normal);
+
+        {tcp, _, WsFrames} ->
+            {M, F} = Body,
+            case WsVersion of
+              hybi ->
+                Reply = fun(close) ->
+                                mochiweb_socket:close(Socket),
+                                exit(normal);
+                            (Payload) ->
+                                M:F(Socket, Payload, State, WsVersion)
+                        end,
+
+                try parse_frames(Socket, WsFrames, []) of
+                    Parsed -> process_frames(Parsed, Reply, [])
+                catch
+                    _:_ -> Reply(close)
+                end;
+
+              hixie ->
+                try handle_frames(WsFrames, []) of
+                    Payload -> M:F(Socket, Payload, State, WsVersion)
+                catch
+                    _:_ ->
+                      mochiweb_socket:close(Socket),
+                      exit(normal)
+                end
+
+            end;
+
+        _ ->
+            handle_invalid_request(Socket)
+    end.
+
+process_frames([], Reply, Acc) ->
+    Reply(lists:reverse(Acc));
+
+process_frames([{Opcode, Payload} | Rest], Reply, Acc) ->
+    case Opcode of
+        8 ->
+            Reply(lists:reverse(Acc)),
+            Reply(close);
+
+        _ ->
+            process_frames(Rest, Reply, [Payload | Acc])
+    end.
+
+reentry(Body) ->
+    fun (Socket, State, WsVersion) ->
+            ?MODULE:after_response(Body, Socket, State, WsVersion)
+    end.
+
+-spec handle_invalid_request(term()) -> no_return().
+handle_invalid_request(Socket) ->
+    mochiweb_socket:close(Socket),
+    exit(normal).
+
+after_response(Body, Socket, State, WsVersion) ->
+    ?MODULE:loop(Socket, Body, State, WsVersion).
+
+%%
+%% Websockets internal functions for RFC6455 (hybi)
+%%
+
+% RFC6455 Handshake
+handshake_key(Key) ->
+    BinKey = list_to_binary(Key),
+    Bin = <<BinKey/binary, "258EAFA5-E914-47DA-95CA-C5AB0DC85B11">>,
+    base64:encode(crypto:hash(sha, Bin)).
+
+parse_frames(_, <<>>, Acc) ->
+    lists:reverse(Acc);
+
+parse_frames(S, <<_Fin:1, 
+               _Rsv:3, 
+               Opcode:4, 
+               _Mask:1, 
+               PayloadLen:7, 
+               MaskKey:4/binary,
+               Payload:PayloadLen/binary-unit:8,
+               Rest/binary>>,
+             Acc) when PayloadLen < 126 ->
+
+    Payload2 = extract_payload(MaskKey, Payload),
+    parse_frames(S, Rest, [{Opcode, Payload2} | Acc]);
+
+parse_frames(S, <<_Fin:1, 
+               _Rsv:3, 
+               Opcode:4, 
+               _Mask:1, 
+               126:7, 
+               PayloadLen:16,
+               MaskKey:4/binary,
+               Payload:PayloadLen/binary-unit:8,
+               Rest/binary>>,
+             Acc) ->
+
+    Payload2 = extract_payload(MaskKey, Payload),
+    parse_frames(S, Rest, [{Opcode, Payload2} | Acc]);
+
+parse_frames(Socket, <<_Fin:1, 
+               _Rsv:3, 
+               _Opcode:4, 
+               _Mask:1, 
+               126:7, 
+               _PayloadLen:16,
+               _MaskKey:4/binary,
+               _/binary-unit:8>> = PartFrame,
+             Acc) ->
+
+    ok = mochiweb_socket:setopts(Socket, [{packet, 0}, {active, once}]),
+    receive
+        {tcp_closed, _} ->
+            mochiweb_socket:close(Socket),
+            exit(normal);
+        {ssl_closed, _} ->
+            mochiweb_socket:close(Socket),
+            exit(normal);
+        {tcp_error, _, _} ->
+            mochiweb_socket:close(Socket),
+            exit(normal);
+
+        {tcp, _, Continuation} ->
+          parse_frames(Socket, <<PartFrame/binary, Continuation/binary>>, Acc);
+
+        _ ->
+            mochiweb_socket:close(Socket),
+            exit(normal)
+    after
+      5000 -> 
+        mochiweb_socket:close(Socket),
+        exit(normal)
+    end;
+
+parse_frames(S, <<_Fin:1,
+               _Rsv:3, 
+               Opcode:4, 
+               _Mask:1, 
+               127:7, 
+               0:1, 
+               PayloadLen:63, 
+               MaskKey:4/binary,
+               Payload:PayloadLen/binary-unit:8,
+               Rest/binary>>,
+             Acc) ->
+
+    Payload2 = extract_payload(MaskKey, Payload),
+    parse_frames(S, Rest, [{Opcode, Payload2} | Acc]).
+
+extract_payload(MaskKey, Payload) ->
+    websocket_unmask(Payload, MaskKey, <<>>).
+
+% Unmasks RFC 6455 message
+websocket_unmask(<<O:32, Rest/bits>>, MaskKey, Acc) ->
+    <<MaskKey2:32>> = MaskKey,
+    T = O bxor MaskKey2,
+    websocket_unmask(Rest, MaskKey, <<Acc/binary, T:32>>);
+websocket_unmask(<<O:24>>, MaskKey, Acc) ->
+    <<MaskKey2:24, _:8>> = MaskKey,
+    T = O bxor MaskKey2,
+    <<Acc/binary, T:24>>;
+websocket_unmask(<<O:16>>, MaskKey, Acc) ->
+    <<MaskKey2:16, _:16>> = MaskKey,
+    T = O bxor MaskKey2,
+    <<Acc/binary, T:16>>;
+websocket_unmask(<<O:8>>, MaskKey, Acc) ->
+    <<MaskKey2:8, _:24>> = MaskKey,
+    T = O bxor MaskKey2,
+    <<Acc/binary, T:8>>;
+websocket_unmask(<<>>, _MaskKey, Acc) ->
+    Acc.
+
+payload_length(N) ->
+    case N of
+        N when N =< 125 -> << N:7 >>;
+        N when N =< 16#ffff -> << 126:7, N:16 >>;
+        N when N =< 16#7fffffffffffffff -> << 127:7, N:64 >>
+    end.
+
+
+%%
+%% Websockets internal functions for hixie-76 websocket version
+%%
+
+handle_frames(<<>>, Frames) ->
+  lists:reverse(Frames);
+handle_frames(<<0, T/binary>>, Frames) ->
+  {Frame, Rest} = handle_frame(T, <<>>),
+  handle_frames(Rest, [Frame | Frames]).
+
+handle_frame(<<255, Rest/binary>>, Buffer) ->
+  {Buffer, Rest};
+handle_frame(<<H, T/binary>>, Buffer) ->
+  handle_frame(T, <<Buffer/binary, H>>).