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Peter Harpending
2025-12-16 22:09:10 -08:00
parent cbfc496057
commit e160701403
11 changed files with 95 additions and 156 deletions
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src/fd_httpd_client.erl
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%%% @doc
%%% front end web development lab Client
%%%
%%% An extremely naive (currently Telnet) client handler.
%%% Unlike other modules that represent discrete processes, this one does not adhere
%%% to any OTP behavior. It does, however, adhere to OTP.
%%%
%%% In some cases it is more comfortable to write socket handlers or a certain
%%% category of state machines as "pure" Erlang processes. This approach is made
%%% OTP-able by use of the proc_lib module, which is the underlying library used
%%% to write the stdlib's behaviors like gen_server, gen_statem, gen_fsm, etc.
%%%
%%% http://erlang.org/doc/design_principles/spec_proc.html
%%% @end
-module(fd_httpd_client).
-vsn("0.1.0").
-author("Peter Harpending <peterharpending@qpq.swiss>").
-copyright("Peter Harpending <peterharpending@qpq.swiss>").
-license("BSD-2-Clause-FreeBSD").
-export([start/1]).
-export([start_link/1, init/2]).
-export([system_continue/3, system_terminate/4,
system_get_state/1, system_replace_state/2]).
%%% Type and Record Definitions
-include("http.hrl").
-include("$zx_include/zx_logger.hrl").
-record(s, {socket = none :: none | gen_tcp:socket(),
next = <<>> :: binary()}).
%% An alias for the state record above. Aliasing state can smooth out annoyances
%% that can arise from using the record directly as its own type all over the code.
-type state() :: #s{}.
%%% Service Interface
-spec start(ListenSocket) -> Result
when ListenSocket :: gen_tcp:socket(),
Result :: {ok, pid()}
| {error, Reason},
Reason :: {already_started, pid()}
| {shutdown, term()}
| term().
%% @private
%% How the fd_httpd_client_man or a prior fd_httpd_client kicks things off.
%% This is called in the context of fd_httpd_client_man or the prior fd_httpd_client.
start(ListenSocket) ->
fd_httpd_client_sup:start_acceptor(ListenSocket).
-spec start_link(ListenSocket) -> Result
when ListenSocket :: gen_tcp:socket(),
Result :: {ok, pid()}
| {error, Reason},
Reason :: {already_started, pid()}
| {shutdown, term()}
| term().
%% @private
%% This is called by the fd_httpd_client_sup. While start/1 is called to iniate a startup
%% (essentially requesting a new worker be started by the supervisor), this is
%% actually called in the context of the supervisor.
start_link(ListenSocket) ->
proc_lib:start_link(?MODULE, init, [self(), ListenSocket]).
-spec init(Parent, ListenSocket) -> no_return()
when Parent :: pid(),
ListenSocket :: gen_tcp:socket().
%% @private
%% This is the first code executed in the context of the new worker itself.
%% This function does not have any return value, as the startup return is
%% passed back to the supervisor by calling proc_lib:init_ack/2.
%% We see the initial form of the typical arity-3 service loop form here in the
%% call to listen/3.
init(Parent, ListenSocket) ->
ok = tell("~p Listening.~n", [self()]),
Debug = sys:debug_options([]),
ok = proc_lib:init_ack(Parent, {ok, self()}),
listen(Parent, Debug, ListenSocket).
-spec listen(Parent, Debug, ListenSocket) -> no_return()
when Parent :: pid(),
Debug :: [sys:dbg_opt()],
ListenSocket :: gen_tcp:socket().
%% @private
%% This function waits for a TCP connection. The owner of the socket is still
%% the fd_httpd_client_man (so it can still close it on a call to fd_httpd_client_man:ignore/0),
%% but the only one calling gen_tcp:accept/1 on it is this process. Closing the socket
%% is one way a manager process can gracefully unblock child workers that are blocking
%% on a network accept.
%%
%% Once it makes a TCP connection it will call start/1 to spawn its successor.
listen(Parent, Debug, ListenSocket) ->
case gen_tcp:accept(ListenSocket) of
{ok, Socket} ->
{ok, _} = start(ListenSocket),
{ok, Peer} = inet:peername(Socket),
ok = tell("~p Connection accepted from: ~p~n", [self(), Peer]),
ok = fd_httpd_client_man:enroll(),
State = #s{socket = Socket},
loop(Parent, Debug, State);
{error, closed} ->
ok = tell("~p Retiring: Listen socket closed.~n", [self()]),
exit(normal)
end.
-spec loop(Parent, Debug, State) -> no_return()
when Parent :: pid(),
Debug :: [sys:dbg_opt()],
State :: state().
%% @private
%% The service loop itself. This is the service state. The process blocks on receive
%% of Erlang messages, TCP segments being received themselves as Erlang messages.
loop(Parent, Debug, State = #s{socket = Socket, next = Next0}) ->
ok = inet:setopts(Socket, [{active, once}]),
receive
{tcp, Socket, Message} ->
Received = <<Next0/binary, Message/binary>>,
case qhl:parse(Socket, Received) of
{ok, Req, Next1} ->
Next2 = handle_request(Socket, Req, Next1),
NewState = State#s{next = Next2},
loop(Parent, Debug, NewState);
Error ->
%% should trigger bad request
tell(error, "~p QHL parse error: ~tp", [?LINE, Error]),
tell(error, "~p bad request:~n~ts", [?LINE, Received]),
fd_httpd_utils:http_err(Socket, 400),
gen_tcp:shutdown(Socket, read_write),
exit(normal)
end;
{tcp_closed, Socket} ->
ok = tell("~p Socket closed, retiring.~n", [self()]),
exit(normal);
{system, From, Request} ->
sys:handle_system_msg(Request, From, Parent, ?MODULE, Debug, State);
Unexpected ->
ok = tell("~p Unexpected message: ~tp", [self(), Unexpected]),
loop(Parent, Debug, State)
end.
-spec system_continue(Parent, Debug, State) -> no_return()
when Parent :: pid(),
Debug :: [sys:dbg_opt()],
State :: state().
%% @private
%% The function called by the OTP internal functions after a system message has been
%% handled. If the worker process has several possible states this is one place
%% resumption of a specific state can be specified and dispatched.
system_continue(Parent, Debug, State) ->
loop(Parent, Debug, State).
-spec system_terminate(Reason, Parent, Debug, State) -> no_return()
when Reason :: term(),
Parent :: pid(),
Debug :: [sys:dbg_opt()],
State :: state().
%% @private
%% Called by the OTP inner bits to allow the process to terminate gracefully.
%% Exactly when and if this is callback gets called is specified in the docs:
%% See: http://erlang.org/doc/design_principles/spec_proc.html#msg
system_terminate(Reason, _Parent, _Debug, _State) ->
exit(Reason).
-spec system_get_state(State) -> {ok, State}
when State :: state().
%% @private
%% This function allows the runtime (or anything else) to inspect the running state
%% of the worker process at any arbitrary time.
system_get_state(State) -> {ok, State}.
-spec system_replace_state(StateFun, State) -> {ok, NewState, State}
when StateFun :: fun(),
State :: state(),
NewState :: term().
%% @private
%% This function allows the system to update the process state in-place. This is most
%% useful for state transitions between code types, like when performing a hot update
%% (very cool, but sort of hard) or hot patching a running system (living on the edge!).
system_replace_state(StateFun, State) ->
{ok, StateFun(State), State}.
%%% http request handling
-spec handle_request(Sock, Request, Received) -> NewReceived
when Sock :: gen_tcp:socket(),
Request :: request(),
Received :: binary(),
NewReceived :: binary().
handle_request(Sock, R = #request{method = M, path = P}, Received) when M =/= undefined, P =/= undefined ->
tell("~tp ~tp ~ts", [self(), M, P]),
route(Sock, M, P, R, Received).
-spec route(Sock, Method, Route, Request, Received) -> NewReceived
when Sock :: gen_tcp:socket(),
Method :: get | post,
Route :: binary(),
Request :: request(),
Received :: binary(),
NewReceived :: binary().
route(Sock, get, Route, Request, Received) ->
case Route of
<<"/ws/echo">> -> ws_echo(Sock, Request) , Received;
<<"/">> -> route_static(Sock, <<"/index.html">>) , Received;
_ -> route_static(Sock, Route) , Received
end;
route(Sock, post, Route, Request, Received) ->
case Route of
<<"/wfcin">> -> wfcin(Sock, Request) , Received;
_ -> fd_httpd_utils:http_err(Sock, 404) , Received
end;
route(Sock, _, _, _, Received) ->
fd_httpd_utils:http_err(Sock, 404),
Received.
-spec route_static(Socket, Route) -> ok
when Socket :: gen_tcp:socket(),
Route :: binary().
route_static(Sock, Route) ->
respond_static(Sock, fd_httpd_sfc:query(Route)).
-spec respond_static(Sock, MaybeEty) -> ok
when Sock :: gen_tcp:socket(),
MaybeEty :: fd_httpd_sfc:maybe_entry().
respond_static(Sock, {found, Entry}) ->
% -record(e, {fs_path :: file:filename(),
% last_modified :: file:date_time(),
% mime_type :: string(),
% encoding :: encoding(),
% contents :: binary()}).
Headers0 =
case fd_httpd_sfc_entry:encoding(Entry) of
gzip -> [{"content-encoding", "gzip"}];
none -> []
end,
Headers1 = [{"content-type", fd_httpd_sfc_entry:mime_type(Entry)} | Headers0],
Response = #response{headers = Headers1,
body = fd_httpd_sfc_entry:contents(Entry)},
fd_httpd_utils:respond(Sock, Response);
respond_static(Sock, not_found) ->
fd_httpd_utils:http_err(Sock, 404).
%% ------------------------------
%% echo
%% ------------------------------
ws_echo(Sock, Request) ->
try
ws_echo2(Sock, Request)
catch
X:Y:Z ->
tell(error, "CRASH ws_echo: ~tp:~tp:~tp", [X, Y, Z]),
fd_httpd_utils:http_err(Sock, 500)
end.
ws_echo2(Sock, Request) ->
case qhl_ws:handshake(Request) of
{ok, Response} ->
fd_httpd_utils:respond(Sock, Response),
ws_echo_loop(Sock);
Error ->
tell("ws_echo: error: ~tp", [Error]),
fd_httpd_utils:http_err(Sock, 400)
end.
ws_echo_loop(Sock) ->
ws_echo_loop(Sock, [], <<>>).
ws_echo_loop(Sock, Frames, Received) ->
tell("~p ws_echo_loop(Sock, ~tp, ~tp)", [self(), Frames, Received]),
case qhl_ws:recv(Sock, Received, 5*qhl_ws:min(), Frames) of
{ok, Message, NewFrames, NewReceived} ->
tell("~p echo message: ~tp", [self(), Message]),
% send the same message back
ok = qhl_ws:send(Sock, Message),
ws_echo_loop(Sock, NewFrames, NewReceived);
Error ->
tell(error, "ws_echo_loop: error: ~tp", [Error]),
qhl_ws:send(Sock, {close, <<>>}),
error(Error)
end.
%% ------------------------------
%% wfc
%% ------------------------------
wfcin(Sock, #request{enctype = json,
cookies = Cookies,
body = #{"wfcin" := Input}}) ->
tell("wfcin good request: ~tp", [Input]),
{Cookie, Ctx0} = ctx(Cookies),
{RespObj, NewCtx} =
%% FIXME: this should really be a new process
try
case wfc_read:expr(Input) of
{ok, Expr, _Rest} ->
case wfc_eval:eval(Expr, Ctx0) of
{ok, noop, Ctx1} -> {fd_httpd_utils:jsgud("<noop>"), Ctx1};
{ok, Sentence, Ctx1} -> {fd_httpd_utils:jsgud(wfc_pp:sentence(Sentence)), Ctx1};
{error, Message} -> {fd_httpd_utils:jsbad(Message), Ctx0}
end;
{error, Message} ->
{fd_httpd_utils:jsbad(Message), Ctx0}
end
catch
error:E:S ->
ErrorMessage = unicode:characters_to_list(io_lib:format("parser crashed: ~p:~p", [E, S])),
{fd_httpd_utils:jsbad(ErrorMessage), Ctx0}
end,
% update cache with new context
ok = fd_cache:set(Cookie, NewCtx),
Body = zj:encode(RespObj),
Response = #response{headers = [{"content-type", "application/json"},
{"set-cookie", ["wfc=", Cookie]}],
body = Body},
fd_httpd_utils:respond(Sock, Response);
wfcin(Sock, Request) ->
tell("wfcin: bad request: ~tp", [Request]),
fd_httpd_utils:http_err(Sock, 400).
-spec ctx(Cookies) -> {Cookie, Context}
when Cookies :: #{binary() := Cookie},
Cookie :: binary(),
Context :: wfc_eval_context:context().
ctx(#{<<"wfc">> := Cookie}) ->
case fd_cache:query(Cookie) of
{ok, Context} -> {Cookie, Context};
error -> {Cookie, wfc_eval_context:default()}
end;
ctx(_) ->
{fd_httpd_utils:new_cookie(), wfc_eval_context:default()}.