%%%------------------------------------------------------------------- %%% File : ejabberd_captcha.erl %%% Author : Evgeniy Khramtsov %%% Purpose : CAPTCHA processing. %%% Created : 26 Apr 2008 by Evgeniy Khramtsov %%% %%% %%% ejabberd, Copyright (C) 2002-2019 ProcessOne %%% %%% This program is free software; you can redistribute it and/or %%% modify it under the terms of the GNU General Public License as %%% published by the Free Software Foundation; either version 2 of the %%% License, or (at your option) any later version. %%% %%% This program is distributed in the hope that it will be useful, %%% but WITHOUT ANY WARRANTY; without even the implied warranty of %%% MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU %%% General Public License for more details. %%% %%% You should have received a copy of the GNU General Public License along %%% with this program; if not, write to the Free Software Foundation, Inc., %%% 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA. %%% %%%------------------------------------------------------------------- -module(ejabberd_captcha). -behaviour(ejabberd_config). -protocol({xep, 158, '1.0'}). -behaviour(gen_server). %% API -export([start_link/0]). %% gen_server callbacks -export([init/1, handle_call/3, handle_cast/2, handle_info/2, terminate/2, code_change/3]). -export([create_captcha/6, build_captcha_html/2, check_captcha/2, process_reply/1, process/2, is_feature_available/0, create_captcha_x/5, opt_type/1, host_up/1, host_down/1, config_reloaded/0, process_iq/1]). -include("xmpp.hrl"). -include("logger.hrl"). -include("ejabberd_http.hrl"). -define(CAPTCHA_LIFETIME, 120000). -define(LIMIT_PERIOD, 60*1000*1000). -type image_error() :: efbig | enodata | limit | malformed_image | timeout. -record(state, {limits = treap:empty() :: treap:treap(), enabled = false :: boolean()}). -record(captcha, {id :: binary(), pid :: pid() | undefined, key :: binary(), tref :: reference(), args :: any()}). start_link() -> gen_server:start_link({local, ?MODULE}, ?MODULE, [], []). -spec captcha_text(undefined | binary()) -> binary(). captcha_text(Lang) -> translate:translate(Lang, <<"Enter the text you see">>). -spec mk_ocr_field(binary() | undefined, binary(), binary()) -> xdata_field(). mk_ocr_field(Lang, CID, Type) -> URI = #media_uri{type = Type, uri = <<"cid:", CID/binary>>}, #xdata_field{var = <<"ocr">>, type = 'text-single', label = captcha_text(Lang), required = true, sub_els = [#media{uri = [URI]}]}. mk_field(Type, Var, Value) -> #xdata_field{type = Type, var = Var, values = [Value]}. -spec create_captcha(binary(), jid(), jid(), binary(), any(), any()) -> {error, image_error()} | {ok, binary(), [text()], [xmlel()]}. create_captcha(SID, From, To, Lang, Limiter, Args) -> case create_image(Limiter) of {ok, Type, Key, Image} -> Id = <<(p1_rand:get_string())/binary>>, JID = jid:encode(From), CID = <<"sha1+", (str:sha(Image))/binary, "@bob.xmpp.org">>, Data = #bob_data{cid = CID, 'max-age' = 0, type = Type, data = Image}, Fs = [mk_field(hidden, <<"FORM_TYPE">>, ?NS_CAPTCHA), mk_field(hidden, <<"from">>, jid:encode(To)), mk_field(hidden, <<"challenge">>, Id), mk_field(hidden, <<"sid">>, SID), mk_ocr_field(Lang, CID, Type)], X = #xdata{type = form, fields = Fs}, Captcha = #xcaptcha{xdata = X}, BodyString = {<<"Your messages to ~s are being blocked. " "To unblock them, visit ~s">>, [JID, get_url(Id)]}, Body = xmpp:mk_text(BodyString, Lang), OOB = #oob_x{url = get_url(Id)}, Hint = #hint{type = 'no-store'}, Tref = erlang:send_after(?CAPTCHA_LIFETIME, ?MODULE, {remove_id, Id}), ets:insert(captcha, #captcha{id = Id, pid = self(), key = Key, tref = Tref, args = Args}), {ok, Id, Body, [Hint, OOB, Captcha, Data]}; Err -> Err end. -spec create_captcha_x(binary(), jid(), binary(), any(), xdata()) -> {ok, xdata()} | {error, image_error()}. create_captcha_x(SID, To, Lang, Limiter, #xdata{fields = Fs} = X) -> case create_image(Limiter) of {ok, Type, Key, Image} -> Id = <<(p1_rand:get_string())/binary>>, CID = <<"sha1+", (str:sha(Image))/binary, "@bob.xmpp.org">>, Data = #bob_data{cid = CID, 'max-age' = 0, type = Type, data = Image}, HelpTxt = translate:translate(Lang, <<"If you don't see the CAPTCHA image here, " "visit the web page.">>), Imageurl = get_url(<>), NewFs = [mk_field(hidden, <<"FORM_TYPE">>, ?NS_CAPTCHA)|Fs] ++ [#xdata_field{type = fixed, var = <<"captcha-fallback-text">>, values = [HelpTxt]}, #xdata_field{type = hidden, var = <<"captchahidden">>, values = [<<"workaround-for-psi">>]}, #xdata_field{type = 'text-single', var = <<"captcha-fallback-url">>, label = translate:translate( Lang, <<"CAPTCHA web page">>), values = [Imageurl]}, mk_field(hidden, <<"from">>, jid:encode(To)), mk_field(hidden, <<"challenge">>, Id), mk_field(hidden, <<"sid">>, SID), mk_ocr_field(Lang, CID, Type)], Captcha = X#xdata{type = form, fields = NewFs}, Tref = erlang:send_after(?CAPTCHA_LIFETIME, ?MODULE, {remove_id, Id}), ets:insert(captcha, #captcha{id = Id, key = Key, tref = Tref}), {ok, [Captcha, Data]}; Err -> Err end. -spec build_captcha_html(binary(), binary()) -> captcha_not_found | {xmlel(), {xmlel(), xmlel(), xmlel(), xmlel()}}. build_captcha_html(Id, Lang) -> case lookup_captcha(Id) of {ok, _} -> ImgEl = #xmlel{name = <<"img">>, attrs = [{<<"src">>, get_url(<>)}], children = []}, TextEl = {xmlcdata, captcha_text(Lang)}, IdEl = #xmlel{name = <<"input">>, attrs = [{<<"type">>, <<"hidden">>}, {<<"name">>, <<"id">>}, {<<"value">>, Id}], children = []}, KeyEl = #xmlel{name = <<"input">>, attrs = [{<<"type">>, <<"text">>}, {<<"name">>, <<"key">>}, {<<"size">>, <<"10">>}], children = []}, FormEl = #xmlel{name = <<"form">>, attrs = [{<<"action">>, get_url(Id)}, {<<"name">>, <<"captcha">>}, {<<"method">>, <<"POST">>}], children = [ImgEl, #xmlel{name = <<"br">>, attrs = [], children = []}, TextEl, #xmlel{name = <<"br">>, attrs = [], children = []}, IdEl, KeyEl, #xmlel{name = <<"br">>, attrs = [], children = []}, #xmlel{name = <<"input">>, attrs = [{<<"type">>, <<"submit">>}, {<<"name">>, <<"enter">>}, {<<"value">>, <<"OK">>}], children = []}]}, {FormEl, {ImgEl, TextEl, IdEl, KeyEl}}; _ -> captcha_not_found end. -spec process_reply(xmpp_element()) -> ok | {error, bad_match | not_found | malformed}. process_reply(#xdata{} = X) -> case {xmpp_util:get_xdata_values(<<"challenge">>, X), xmpp_util:get_xdata_values(<<"ocr">>, X)} of {[Id], [OCR]} -> case check_captcha(Id, OCR) of captcha_valid -> ok; captcha_non_valid -> {error, bad_match}; captcha_not_found -> {error, not_found} end; _ -> {error, malformed} end; process_reply(#xcaptcha{xdata = #xdata{} = X}) -> process_reply(X); process_reply(_) -> {error, malformed}. process_iq(#iq{type = set, lang = Lang, sub_els = [#xcaptcha{} = El]} = IQ) -> case process_reply(El) of ok -> xmpp:make_iq_result(IQ); {error, malformed} -> Txt = <<"Incorrect CAPTCHA submit">>, xmpp:make_error(IQ, xmpp:err_bad_request(Txt, Lang)); {error, _} -> Txt = <<"The CAPTCHA verification has failed">>, xmpp:make_error(IQ, xmpp:err_not_allowed(Txt, Lang)) end; process_iq(#iq{type = get, lang = Lang} = IQ) -> Txt = <<"Value 'get' of 'type' attribute is not allowed">>, xmpp:make_error(IQ, xmpp:err_not_allowed(Txt, Lang)); process_iq(#iq{lang = Lang} = IQ) -> Txt = <<"No module is handling this query">>, xmpp:make_error(IQ, xmpp:err_service_unavailable(Txt, Lang)). process(_Handlers, #request{method = 'GET', lang = Lang, path = [_, Id]}) -> case build_captcha_html(Id, Lang) of {FormEl, _} when is_tuple(FormEl) -> Form = #xmlel{name = <<"div">>, attrs = [{<<"align">>, <<"center">>}], children = [FormEl]}, ejabberd_web:make_xhtml([Form]); captcha_not_found -> ejabberd_web:error(not_found) end; process(_Handlers, #request{method = 'GET', path = [_, Id, <<"image">>], ip = IP}) -> {Addr, _Port} = IP, case lookup_captcha(Id) of {ok, #captcha{key = Key}} -> case create_image(Addr, Key) of {ok, Type, _, Img} -> {200, [{<<"Content-Type">>, Type}, {<<"Cache-Control">>, <<"no-cache">>}, {<<"Last-Modified">>, list_to_binary(httpd_util:rfc1123_date())}], Img}; {error, limit} -> ejabberd_web:error(not_allowed); _ -> ejabberd_web:error(not_found) end; _ -> ejabberd_web:error(not_found) end; process(_Handlers, #request{method = 'POST', q = Q, lang = Lang, path = [_, Id]}) -> ProvidedKey = proplists:get_value(<<"key">>, Q, none), case check_captcha(Id, ProvidedKey) of captcha_valid -> Form = #xmlel{name = <<"p">>, attrs = [], children = [{xmlcdata, translate:translate(Lang, <<"The CAPTCHA is valid.">>)}]}, ejabberd_web:make_xhtml([Form]); captcha_non_valid -> ejabberd_web:error(not_allowed); captcha_not_found -> ejabberd_web:error(not_found) end; process(_Handlers, _Request) -> ejabberd_web:error(not_found). host_up(Host) -> gen_iq_handler:add_iq_handler(ejabberd_sm, Host, ?NS_CAPTCHA, ?MODULE, process_iq). host_down(Host) -> gen_iq_handler:remove_iq_handler(ejabberd_sm, Host, ?NS_CAPTCHA). config_reloaded() -> gen_server:call(?MODULE, config_reloaded, timer:minutes(1)). init([]) -> mnesia:delete_table(captcha), ets:new(captcha, [named_table, public, {keypos, #captcha.id}]), case check_captcha_setup() of true -> register_handlers(), ejabberd_hooks:add(config_reloaded, ?MODULE, config_reloaded, 50), {ok, #state{enabled = true}}; false -> {ok, #state{enabled = false}}; {error, Reason} -> {stop, Reason} end. handle_call({is_limited, Limiter, RateLimit}, _From, State) -> NowPriority = now_priority(), CleanPriority = NowPriority + (?LIMIT_PERIOD), Limits = clean_treap(State#state.limits, CleanPriority), case treap:lookup(Limiter, Limits) of {ok, _, Rate} when Rate >= RateLimit -> {reply, true, State#state{limits = Limits}}; {ok, Priority, Rate} -> NewLimits = treap:insert(Limiter, Priority, Rate + 1, Limits), {reply, false, State#state{limits = NewLimits}}; _ -> NewLimits = treap:insert(Limiter, NowPriority, 1, Limits), {reply, false, State#state{limits = NewLimits}} end; handle_call(config_reloaded, _From, #state{enabled = Enabled} = State) -> State1 = case is_feature_available() of true when not Enabled -> case check_captcha_setup() of true -> register_handlers(), State#state{enabled = true}; _ -> State end; false when Enabled -> unregister_handlers(), State#state{enabled = false}; _ -> State end, {reply, ok, State1}; handle_call(_Request, _From, State) -> {reply, bad_request, State}. handle_cast(_Msg, State) -> {noreply, State}. handle_info({remove_id, Id}, State) -> ?DEBUG("captcha ~p timed out", [Id]), case ets:lookup(captcha, Id) of [#captcha{args = Args, pid = Pid}] -> callback(captcha_failed, Pid, Args), ets:delete(captcha, Id); _ -> ok end, {noreply, State}; handle_info(_Info, State) -> {noreply, State}. terminate(_Reason, #state{enabled = Enabled}) -> if Enabled -> unregister_handlers(); true -> ok end, ejabberd_hooks:delete(config_reloaded, ?MODULE, config_reloaded, 50). register_handlers() -> ejabberd_hooks:add(host_up, ?MODULE, host_up, 50), ejabberd_hooks:add(host_down, ?MODULE, host_down, 50), lists:foreach(fun host_up/1, ejabberd_config:get_myhosts()). unregister_handlers() -> ejabberd_hooks:delete(host_up, ?MODULE, host_up, 50), ejabberd_hooks:delete(host_down, ?MODULE, host_down, 50), lists:foreach(fun host_down/1, ejabberd_config:get_myhosts()). code_change(_OldVsn, State, _Extra) -> {ok, State}. create_image() -> create_image(undefined). create_image(Limiter) -> Key = str:substr(p1_rand:get_string(), 1, 6), create_image(Limiter, Key). create_image(Limiter, Key) -> case is_limited(Limiter) of true -> {error, limit}; false -> do_create_image(Key) end. do_create_image(Key) -> FileName = get_prog_name(), Cmd = lists:flatten(io_lib:format("~s ~s", [FileName, Key])), case cmd(Cmd) of {ok, <<137, $P, $N, $G, $\r, $\n, 26, $\n, _/binary>> = Img} -> {ok, <<"image/png">>, Key, Img}; {ok, <<255, 216, _/binary>> = Img} -> {ok, <<"image/jpeg">>, Key, Img}; {ok, <<$G, $I, $F, $8, X, $a, _/binary>> = Img} when X == $7; X == $9 -> {ok, <<"image/gif">>, Key, Img}; {error, enodata = Reason} -> ?ERROR_MSG("Failed to process output from \"~s\". " "Maybe ImageMagick's Convert program " "is not installed.", [Cmd]), {error, Reason}; {error, Reason} -> ?ERROR_MSG("Failed to process an output from \"~s\": ~p", [Cmd, Reason]), {error, Reason}; _ -> Reason = malformed_image, ?ERROR_MSG("Failed to process an output from \"~s\": ~p", [Cmd, Reason]), {error, Reason} end. get_prog_name() -> case ejabberd_config:get_option(captcha_cmd) of undefined -> ?DEBUG("The option captcha_cmd is not configured, " "but some module wants to use the CAPTCHA " "feature.", []), false; FileName -> FileName end. get_url(Str) -> CaptchaHost = ejabberd_config:get_option(captcha_host, <<"">>), case str:tokens(CaptchaHost, <<":">>) of [Host] -> <<"http://", Host/binary, "/captcha/", Str/binary>>; [<<"http", _/binary>> = TransferProt, Host] -> <>; [Host, PortString] -> TransferProt = iolist_to_binary(atom_to_list(get_transfer_protocol(PortString))), <>; [TransferProt, Host, PortString] -> <>; _ -> <<"http://", (ejabberd_config:get_myname())/binary, "/captcha/", Str/binary>> end. get_transfer_protocol(PortString) -> PortNumber = binary_to_integer(PortString), PortListeners = get_port_listeners(PortNumber), get_captcha_transfer_protocol(PortListeners). get_port_listeners(PortNumber) -> AllListeners = ejabberd_config:get_option(listen, []), lists:filter( fun({{Port, _IP, _Transport}, _Module, _Opts}) -> Port == PortNumber end, AllListeners). get_captcha_transfer_protocol([]) -> throw(<<"The port number mentioned in captcha_host " "is not a ejabberd_http listener with " "'captcha' option. Change the port number " "or specify http:// in that option.">>); get_captcha_transfer_protocol([{_, ejabberd_http, Opts} | Listeners]) -> case proplists:get_bool(captcha, Opts) of true -> case proplists:get_bool(tls, Opts) of true -> https; false -> http end; false -> get_captcha_transfer_protocol(Listeners) end; get_captcha_transfer_protocol([_ | Listeners]) -> get_captcha_transfer_protocol(Listeners). is_limited(undefined) -> false; is_limited(Limiter) -> case ejabberd_config:get_option(captcha_limit) of undefined -> false; Int -> case catch gen_server:call(?MODULE, {is_limited, Limiter, Int}, 5000) of true -> true; false -> false; Err -> ?ERROR_MSG("Call failed: ~p", [Err]), false end end. -define(CMD_TIMEOUT, 5000). -define(MAX_FILE_SIZE, 64 * 1024). cmd(Cmd) -> Port = open_port({spawn, Cmd}, [stream, eof, binary]), TRef = erlang:start_timer(?CMD_TIMEOUT, self(), timeout), recv_data(Port, TRef, <<>>). recv_data(Port, TRef, Buf) -> receive {Port, {data, Bytes}} -> NewBuf = <>, if byte_size(NewBuf) > (?MAX_FILE_SIZE) -> return(Port, TRef, {error, efbig}); true -> recv_data(Port, TRef, NewBuf) end; {Port, {data, _}} -> return(Port, TRef, {error, efbig}); {Port, eof} when Buf /= <<>> -> return(Port, TRef, {ok, Buf}); {Port, eof} -> return(Port, TRef, {error, enodata}); {timeout, TRef, _} -> return(Port, TRef, {error, timeout}) end. return(Port, TRef, Result) -> misc:cancel_timer(TRef), catch port_close(Port), Result. is_feature_available() -> case get_prog_name() of Prog when is_binary(Prog) -> true; false -> false end. check_captcha_setup() -> case is_feature_available() of true -> case create_image() of {ok, _, _, _} -> true; Err -> ?CRITICAL_MSG("Captcha is enabled in the option captcha_cmd, " "but it can't generate images.", []), Err end; false -> false end. lookup_captcha(Id) -> case ets:lookup(captcha, Id) of [C] -> {ok, C}; _ -> {error, enoent} end. -spec check_captcha(binary(), binary()) -> captcha_not_found | captcha_valid | captcha_non_valid. check_captcha(Id, ProvidedKey) -> case ets:lookup(captcha, Id) of [#captcha{pid = Pid, args = Args, key = ValidKey, tref = Tref}] -> ets:delete(captcha, Id), misc:cancel_timer(Tref), if ValidKey == ProvidedKey -> callback(captcha_succeed, Pid, Args), captcha_valid; true -> callback(captcha_failed, Pid, Args), captcha_non_valid end; _ -> captcha_not_found end. clean_treap(Treap, CleanPriority) -> case treap:is_empty(Treap) of true -> Treap; false -> {_Key, Priority, _Value} = treap:get_root(Treap), if Priority > CleanPriority -> clean_treap(treap:delete_root(Treap), CleanPriority); true -> Treap end end. -spec callback(captcha_succeed | captcha_failed, pid(), term()) -> any(). callback(Result, _Pid, F) when is_function(F) -> F(Result); callback(Result, Pid, Args) when is_pid(Pid) -> Pid ! {Result, Args}; callback(_, _, _) -> ok. now_priority() -> -erlang:system_time(microsecond). -spec opt_type(atom()) -> fun((any()) -> any()) | [atom()]. opt_type(captcha_cmd) -> fun (FileName) -> F = iolist_to_binary(FileName), if F /= <<"">> -> F end end; opt_type(captcha_host) -> fun iolist_to_binary/1; opt_type(captcha_limit) -> fun (I) when is_integer(I), I > 0 -> I end; opt_type(_) -> [captcha_cmd, captcha_host, captcha_limit].