wip: websocket frame parsing

this is just retarded, i'm just going to ignore

src/fd_ws.erl

@@ -8,7 +8,10 @@
 
 -export([
     handshake/1,
-    response_token/1
+    response_token/1,
+    recv/2,
+    send/2,
+    pong/1,
 ]).
 
 -include("http.hrl").
@@ -22,7 +25,7 @@
          Result           :: {ok, ClientProtocols, ClientExtensions, DraftResponse}
                            | {error, Reason},
          ClientProtocols  :: [binary()],
-         ClientExtensions :: [binary()],
+         ClientExtensions :: binary(),
          DraftResponse    :: response(),
          Reason           :: any().
 % @doc
@@ -41,88 +44,211 @@
 %                  {"Connection",           "Upgrade"},
 %                  {"Upgrade",              "websocket"}].
 %
-% YOU are responsible for dealing with any cookie logic, adding the retarded
-% web date, rendering the response, etc.
+% YOU are responsible for dealing with any cookie logic, authentication logic,
+% validating the Origin field, implementing cross-site-request-forgery, adding
+% the retarded web date, rendering the response, sending it over the socket,
+% etc.
+%
+% ClientExtensions only joins the <<"sec-websocket-extensions">> fields with ", "
 
 handshake(R = #request{method = get, headers = Hs}) ->
     %% downcase the headers because have to match on them
     handshake2(R#request{headers = casefold_headers(Hs)});
 handshake(_) ->
-    {error, bad_request}.
+    {error, bad_method}.
 
 
-casefold_headers([{K, V} | Rest]) ->
-    [{unicode:characters_to_binary(string:casefold(K)), V} | casefold_headers(Rest)];
-casefold_headers([]) ->
-    [].
 
-handshake2(Req = #request{headers = DowncaseHeaders}) ->
+-spec casefold_headers(Headers) -> DowncaseHeaders
+    when Headers         :: [{Key, Value}],
+         Key             :: binary(),
+         Value           :: binary(),
+         DowncaseHeaders :: [{LowercaseKey, Value}],
+         LowercaseKey    :: binary().
+% @private
+% casefold all the keys in the header because they're case insensitive
+
+casefold_headers(Headers) ->
+    Downcase =
+        fun({K, V}) ->
+            NewKey = unicode:characters_to_binary(string:casefold(K)),
+            {NewKey, V}
+        end,
+    lists:map(Downcase, Headers).
+
+
+
+-spec handshake2(DowncaseReq) -> Result
+    when DowncaseReq      :: request(),
+         Result           :: {ok, ClientProtocols, ClientExtensions, DraftResponse}
+                           | {error, Reason},
+         ClientProtocols  :: [binary()],
+         ClientExtensions :: binary(),
+         DraftResponse    :: response(),
+         Reason           :: any().
+% @private
+% we may assume (WMA) method=get and headers have all been downcased
+
+handshake2(#request{headers = DowncaseHeaders}) ->
     % headers MUST contain fields:
     % sec-websocket-key:     _          % arbitrary
     % sec-websocket-version: 13         % must be EXACTLY 13
     % connection:            Upgrade    % must include the token "Upgrade"
     % upgrade:               websocket  % must include the token "websocket"
-    MapHeaders       = maps:from_list(DowncaseHeaders)
-    ClientProtocols  = client_protocols(MapHeaders),
-    ClientExtensions = client_extensions(MapHeaders),
-    case validate_headers(MapHeaders) of
+    MapHeaders         = maps:from_list(DowncaseHeaders),
+    ClientProtocols    = client_protocols(MapHeaders),
+    ClientExtensions   = client_extensions(DowncaseHeaders),
+    MaybeResponseToken = validate_headers(MapHeaders),
+    case MaybeResponseToken of
         {ok, ResponseToken} ->
-            {ok, ClientProtocols,
-                 ClientExtensions,
+            DraftResponse =
                  #response{code = 101,
                            slogan = "Switching Protocols",
                            headers = [{"Sec-WebSocket-Accept", ResponseToken},
                                       {"Connection",           "Upgrade"},
-                                      {"Upgrade",              "websocket"}]}};
+                                      {"Upgrade",              "websocket"}]},
+            {ok, ClientProtocols,
+                 ClientExtensions,
+                 DraftResponse};
         Error ->
             Error
     end.
 
-client_protocols(#{<<"sec-websocket-protocol">> := CommaSeparatedProtocols}) ->
-    Protocols = string:split(CommaSeparatedProtocols, ",", all),
-    Clean =
-        fun(String) ->
-            unicode:characters_to_binary(string:trim(String))
-        end,
-    lists:map(Clean, Protocols).
 
-client_extensions(#{<<"sec-websocket-extensions">> := CommaSeparatedExtensions}) ->
-    Extensions = string:split(CommaSeparatedExtensions, ",", all),
-    Clean =
-        fun(String) ->
-            unicode:characters_to_binary(string:trim(String))
-        end,
-    lists:map(Clean, Extensions).
 
+-spec client_protocols(Headers) -> Protocols
+    when Headers   :: [{binary(), binary()}],
+         Protocols :: [binary()].
+% @private
+% needs to loop through all the headers and unfuck multiline bullshit
+
+client_protocols(FuckedHeaders) ->
+    unfuck_protocol_string(FuckedHeaders, []).
+
+unfuck_protocol_string([{<<"sec-websocket-protocol">>, Part} | Rest], Acc) ->
+    unfuck_protocol_string(Rest, [Part | Acc]);
+unfuck_protocol_string([_ | Rest], Acc) ->
+    unfuck_protocol_string(Rest, Acc);
+unfuck_protocol_string([], PartsRev) ->
+    Parts  = lists:reverse(PartsRev),
+    % have to join everything together and then re-split
+    CSVBin = unicode:characters_to_binary(lists:join(", ", Parts)),
+    % after the surgery
+    TrannyParts = string:split(CSVBin, ",", all),
+    % trim the parts
+    JewParts = lists:map(fun circumcise/1, TrannyParts),
+    JewParts.
+
+
+
+-spec client_extensions(Headers) -> binary()
+    when Headers    :: [{Key, Val}],
+         Key        :: binary(),
+         Val        :: binary().
+
+client_extensions(DowncaseHeaders) ->
+    unfuck_extensions_string(DowncaseHeaders, []).
+
+
+-spec unfuck_extensions_string(KVPairs, Acc) -> Unfucked
+    when KVPairs  :: [{Key :: binary(), Val :: binary()}],
+         Acc      :: Unfucked,
+         Unfucked :: binary().
+% @private
+% quoth section 9.1: https://datatracker.ietf.org/doc/html/rfc6455#section-9.1
+%
+% > Note that like other HTTP header fields, this header field MAY be
+% > split or combined across multiple lines.  Ergo, the following are
+% > equivalent:
+% >
+% >       Sec-WebSocket-Extensions: foo
+% >       Sec-WebSocket-Extensions: bar; baz=2
+% >
+% > is exactly equivalent to
+% >
+% >       Sec-WebSocket-Extensions: foo, bar; baz=2
+%
+% basically have to go through the entire proplist of headers, and if it
+% matches <<"sec-websocket-extensions">>, then csv its value to the thing
+% @end
+
+unfuck_extensions_string([{<<"sec-websocket-extensions">>, Part} | Rest], Acc) ->
+    unfuck_extensions_string(Rest, [Part | Acc]);
+unfuck_extensions_string([_ | Rest], Acc) ->
+    unfuck_extensions_string(Rest, Acc);
+unfuck_extensions_string([], PartsRev) ->
+    % in the example above, PartsRev = [<<"bar; baz=2">>, <<"foo">>],
+    % so need to reverse and then join with commas
+    circumcise(lists:join(<<", ">>, lists:reverse(PartsRev))).
+
+
+
+-spec circumcise(unicode:chardata()) -> binary().
+% @private delete leading/trailing whitespace then convert to binary
+
+circumcise(String) ->
+    unicode:characters_to_binary(string:trim(String)).
+
+
+
+-spec validate_headers(HeadersMap) -> Result
+    when HeadersMap    :: #{Key :: binary() := Val :: binary()},
+         Result        :: {ok, ResponseToken}
+                        | {error, Reason},
+         ResponseToken :: binary(),
+         Reason        :: any().
+% @private
+% validate:
+%   Upgrade: websocket
+%   Connection: Upgrade
+%   Sec-WebSocket-Version: 13
 
 validate_headers(#{<<"sec-websocket-key">>     := ChallengeToken,
                    <<"sec-websocket-version">> := WS_Vsn,
                    <<"connection">>            := Connection,
                    <<"upgrade">>               := Upgrade}) ->
+    BadUpgrade    = bad_upgrade(Upgrade),
+    BadConnection = bad_connection(Connection),
+    BadVersion    = bad_version(WS_Vsn),
     if
-        bad_upgrade(Upgrade)       -> {error, {bad_upgrade, Upgrade}};
-        bad_connection(Connection) -> {error, {bad_connection, Connection}};
-        bad_version(WS_Vsn)        -> {error, {bad_version, WS_Vsn}};
-        true                       -> {ok, response_token(ChallengeToken)}
-    end.
+        BadUpgrade    -> {error, {bad_upgrade, Upgrade}};
+        BadConnection -> {error, {bad_connection, Connection}};
+        BadVersion    -> {error, {bad_version, WS_Vsn}};
+        true          -> {ok, response_token(ChallengeToken)}
+    end;
+validate_headers(_) ->
+    {error, bad_request}.
+
+
+
+-spec bad_upgrade(binary()) -> true | false.
+% @private string must include "websocket" as a token
 
-% string must include "websocket" as a token
 bad_upgrade(Str) ->
     case string:find(Str, "websocket") of
         nomatch -> true;
         _       -> false
     end.
 
-% string must include "Upgrade" as a token
+
+
+-spec bad_connection(binary()) -> true | false.
+% @private string must include "Upgrade" as a token
+
 bad_connection(Str) ->
     case string:find(Str, "Upgrade") of
         nomatch -> true;
         _       -> false
     end.
 
-% version must be EXACTLY <<"13">>
-bad_version(<<"13">> -> false;
-bad_version(_)       -> true.
+
+
+-spec bad_version(binary()) -> true | false.
+% @private version must be EXACTLY <<"13">>
+
+bad_version(<<"13">>) -> false;
+bad_version(_)        -> true.
+
 
 
 -spec response_token(binary()) -> binary().
@@ -157,3 +283,204 @@ response_token(ChallengeToken) when is_binary(ChallengeToken) ->
     ConcatString = <<ChallengeToken/binary, MagicString/binary>>,
     Sha1         = crypto:hash(sha, ConcatString),
     base64:encode(Sha1).
+
+
+
+-type opcode() :: continuation
+                | text
+                | binary
+                | close
+                | ping
+                | pong.
+
+-record(frame,
+        {fin            = none :: none | boolean(),
+         rsv            = none :: none | <<_:3>>,
+         opcode         = none :: none | opcode(),
+         mask           = none :: none | boolean(),
+         payload_length = none :: none | non_neg_integer(),
+         masking_key    = none :: none | <<_:256>>,
+         payload        = none :: none | binary()}).
+
+-type frame() :: #frame{}.
+
+
+
+-spec recv(Socket, Received) -> Result
+    when Socket   :: gen_tcp:socket(),
+         Received :: binary(),
+         Result   :: {ok, binary()}
+                   | {error, Reason}
+         Reason   :: any().
+
+recv(Sock, Recv) ->
+    recv(#frame{}, Sock, Recv).
+
+
+%% frame: 1 bit
+recv_frame(Frame = #frame{fin = none}, Sock, <<FinBit:1, Rest/bits>>) ->
+    NewFin =
+        case FinBit of
+            0 -> false;
+            1 -> true
+        end,
+    NewFrame = Frame#frame{fin = NewFin},
+    recv_frame(NewFrame, Sock, Rest);
+recv_frame(Frame = #frame{fin = none}, Sock, <<>>) ->
+    case inet:setopts(Sock, [{active, once}]) of
+        ok ->
+            receive
+                {tcp, Sock, Bin}            -> recv_frame(Frame, Sock, Bin);
+                {tcp_closed, Socket}        -> {error, tcp_closed};
+                {tcp_error, Socket, Reason} -> {error, {tcp_error, Reason}}
+            after 3000 ->
+                {error, timeout}
+            end;
+        {error, Reason} ->
+            {error, {inet, Reason}}
+    end;
+%% rsv: 3 bits
+recv_frame(Frame = #frame{rsv = none}, Sock, <<RSV:3/bits, Rest/bits>>) ->
+    NewFrame = Frame#frame{rsv = RSV},
+    recv_frame(NewFrame, Sock, Rest);
+recv_frame(Frame = #frame{rsv = none}, Sock, Received) ->
+    case inet:setopts(Sock, [{active, once}]) of
+        ok ->
+            receive
+                {tcp, Sock, Bin}            -> recv_frame(Frame, Sock, <<Received/bits, Bin/binary>>);
+                {tcp_closed, Socket}        -> {error, tcp_closed};
+                {tcp_error, Socket, Reason} -> {error, {tcp_error, Reason}}
+            after 3000 ->
+                {error, timeout}
+            end;
+        {error, Reason} ->
+            {error, {inet, Reason}}
+    end;
+%% opcode
+recv_frame(Frame = #frame{opcode = none}, Sock, <<OpcodeInt:4, Rest/bits>>) ->
+    if
+        OpcodeInt =:= 
+    end;
+
+
+-spec send(Socket, Payload) -> Result
+    when Socket   :: gen_tcp:socket(),
+         Payload  :: iodata(),
+         Result   :: ok
+                   | {error, Reason},
+         Reason   :: closed | {timeout, RestData} | inet:posix(),
+         RestData :: binary() | erlang:iovec().
+% @doc
+% send binary data over Socket. handles frame nonsense
+% @end
+
+send(Socket, Payload) ->
+    BPayload = unicode:characters_to_binary(Payload),
+    Frame = payload_to_frame(BPayload),
+    send_frame(Socket, Frame).
+
+
+payload_to_frame(Payload) when byte_size(Payload) < (1 bsl 64) ->
+    #frame{fin            = true,
+           opcode         = binary,
+           mask           = false,
+           payload_length = byte_size(Payload),
+           masking_key    = none,
+           payload        = Payload}.
+
+
+
+-spec send_frame(Sock, Frame) -> Result
+    when Sock     :: gen_tcp:socket(),
+         Frame    :: frame(),
+         Result   :: ok
+                   | {error, Reason},
+         Reason   :: closed | {timeout, RestData} | inet:posix(),
+         RestData :: binary() | erlang:iovec().
+% @private
+% send a frame on the socket
+% @end
+
+send_frame(Sock, Frame) ->
+    Binary = render_frame(Frame),
+    gen_tcp:send(Sock, Binary).
+
+
+
+-spec render_frame(Frame) -> Binary
+    when Frame  :: frame(),
+         Binary :: binary().
+% @private
+% render a frame
+% @end
+
+render_frame(#frame{fin            = Fin,
+                    opcode         = Opcode,
+                    payload_length = Len,
+                    payload        = Payload}) ->
+    BFin =
+        case Fin of
+            true  -> <<1:1>>;
+            false -> <<0:1>>
+        end,
+    BRSV = <<0:3>>,
+    BOpcode =
+        case Opcode of
+            continuation -> << 0:1>>;
+            text         -> << 1:1>>;
+            binary       -> << 2:1>>;
+            close        -> << 8:1>>;
+            ping         -> << 9:1>>;
+            pong         -> <<10:1>>
+        end,
+    BMask = <<0:1>>,
+    BPayloadLength = render_payload_length(Len),
+    <<BFin/bits,
+      BRSV/bits,
+      BOpcode/bits,
+      BMask/bits,
+      BPayloadLength/bits,
+      Payload/bits>>.
+
+
+
+-spec render_payload_length(non_neg_integer()) -> binary().
+% @private
+% > Payload length:  7 bits, 7+16 bits, or 7+64 bits
+% >
+% >    The length of the "Payload data", in bytes: if 0-125, that is the
+% >    payload length.  If 126, the following 2 bytes interpreted as a
+% >    16-bit unsigned integer are the payload length.  If 127, the
+% >    following 8 bytes interpreted as a 64-bit unsigned integer (the
+% >    most significant bit MUST be 0) are the payload length.  Multibyte
+% >    length quantities are expressed in network byte order.  Note that
+% >    in all cases, the minimal number of bytes MUST be used to encode
+% >    the length, for example, the length of a 124-byte-long string
+% >    can't be encoded as the sequence 126, 0, 124.  The payload length
+% >    is the length of the "Extension data" + the length of the
+% >    "Application data".  The length of the "Extension data" may be
+% >    zero, in which case the payload length is the length of the
+% >    "Application data".
+
+render_payload_length(Len) when 0 =< Len, Len =< 125 ->
+    <<Len:7>>;
+render_payload_length(Len) when 126 =< Len, Len =< 2#1111_1111_1111_1111 ->
+    <<126:7, Len:16>>;
+render_payload_length(Len) when (1 bsl 16) =< Len, Len < (1 bsl 63) ->
+    <<127:7, Len:64>>.
+
+
+
+-spec pong(Socket) ->  Result
+    when Socket   :: gen_tcp:socket(),
+         Result   :: ok
+                   | {error, Reason},
+         Reason   :: closed | {timeout, RestData} | inet:posix(),
+         RestData :: binary() | erlang:iovec().
+
+pong(Sock) ->
+    Frame = #frame{fin            = true,
+                   opcode         = pong,
+                   payload_length = 0,
+                   payload        = <<>>},
+    send_frame(Sock, Frame).