%-*-Mode:erlang;coding:utf-8;tab-width:4;c-basic-offset:4;indent-tabs-mode:()-*- % ex: set ft=erlang fenc=utf-8 sts=4 ts=4 sw=4 et nomod: %%% %%%------------------------------------------------------------------------ %%% @doc %%% ==Erlang syslog Client Interface== %%% A minimal syslog client interface that supports both RFC3164 and RFC5424. %%% @end %%% %%% MIT License %%% %%% Copyright (c) 2016-2018 Michael Truog %%% %%% 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. %%% %%% @author Michael Truog %%% @copyright 2016-2018 Michael Truog %%% @version 1.7.3 {@date} {@time} %%%------------------------------------------------------------------------ -module(syslog_socket). -author('mjtruog at protonmail dot com'). -behaviour(gen_server). %% external interface -export([start_link/1, start_monitor/1, stop_link/1, stop_link/2, stop_monitor/1, stop_monitor/2, send/3, send/4, send/5, facility/1, facility_valid/1, severity/1, severity_valid/1]). %% gen_server callbacks -export([init/1, handle_call/3, handle_cast/2, handle_info/2, terminate/2, code_change/3]). -define(TRANSPORT_DEFAULT, local). -define(PROTOCOL_DEFAULT, rfc3164). -define(UTF8_DEFAULT, true). -define(FACILITY_DEFAULT, local0). -define(TIMEOUT_DEFAULT, 5000). % milliseconds -define(TIMEOUT_MAX_ERLANG, 4294967295). % milliseconds -define(SP, $\s). -type transport() :: local | udp | tcp | tls. -type protocol() :: rfc3164 | rfc5424. -type timeout_milliseconds() :: 1..?TIMEOUT_MAX_ERLANG. -type app_name() :: nonempty_string(). -type facility() :: kernel | user | mail | daemon | auth0 | syslog | print | news | uucp | clock0 | auth1 | ftp | ntp | auth2 | auth3 | clock1 | local0 | local1 | local2 | local3 | local4 | local5 | local6 | local7 | non_neg_integer() | % common aliases auth | authpriv | cron | kern | lpr | security. -type severity() :: emergency | alert | critical | error | warning | notice | informational | debug | 0..7 | % common aliases emerg | panic | crit | err | warn | info. -type message_id() :: string() | binary(). -type options() :: list({transport, transport()} | {transport_options, list()} | {protocol, protocol()} | {utf8, boolean()} | {facility, facility()} | {app_name, app_name()} | {path, nonempty_string()} | {host, inet:ip_address() | inet:hostname()} | {port, undefined | inet:port_number()} | {timeout, timeout_milliseconds()}). -export_type([transport/0, protocol/0, timeout_milliseconds/0, app_name/0, facility/0, severity/0, message_id/0, options/0]). -record(state, { transport :: transport(), transport_options :: list(), protocol :: protocol(), utf8 :: boolean(), utf8_bom :: binary(), facility :: non_neg_integer(), app_name :: app_name(), path :: nonempty_string(), host :: inet:ip_address() | inet:hostname(), port :: inet:port_number(), timeout :: pos_integer(), socket = undefined :: undefined | inet:socket() | ssl:sslsocket(), hostname = undefined :: undefined | string(), os_pid = undefined :: undefined | string() }). %%%------------------------------------------------------------------------ %%% External interface functions %%%------------------------------------------------------------------------ %%------------------------------------------------------------------------- %% @doc %% ===Start a syslog socket with a link.=== %% Connection is immediate within the new Erlang process. %% @end %%------------------------------------------------------------------------- -spec start_link(Options :: options()) -> {ok, pid()} | {error, any()}. start_link(Options) -> case start(Options) of {ok, Pid} = Success -> true = erlang:link(Pid), Success; {error, _} = Error -> Error end. %%------------------------------------------------------------------------- %% @doc %% ===Start a syslog socket with a monitor.=== %% Connection is immediate within the new Erlang process. %% @end %%------------------------------------------------------------------------- -spec start_monitor(Options :: options()) -> {ok, pid()} | {error, any()}. start_monitor(Options) -> case start(Options) of {ok, Pid} = Success -> _ = erlang:monitor(process, Pid), Success; {error, _} = Error -> Error end. %%------------------------------------------------------------------------- %% @doc %% ===Stop an existing syslog socket link asynchronously.=== %% @end %%------------------------------------------------------------------------- -spec stop_link(Pid :: pid()) -> ok. stop_link(Pid) -> gen_server:cast(Pid, stop). %%------------------------------------------------------------------------- %% @doc %% ===Stop an existing syslog socket link synchronously.=== %% @end %%------------------------------------------------------------------------- -spec stop_link(Pid :: pid(), Timeout :: timeout_milliseconds()) -> ok. stop_link(Pid, Timeout) -> gen_server:call(Pid, stop, Timeout). %%------------------------------------------------------------------------- %% @doc %% ===Stop an existing syslog socket monitor asynchronously.=== %% The parent process will still receive {'DOWN', _, process, Pid, Info}. %% @end %%------------------------------------------------------------------------- -spec stop_monitor(Pid :: pid()) -> ok. stop_monitor(Pid) -> gen_server:cast(Pid, stop). %%------------------------------------------------------------------------- %% @doc %% ===Stop an existing syslog socket monitor synchronously.=== %% @end %%------------------------------------------------------------------------- -spec stop_monitor(Pid :: pid(), Timeout :: timeout_milliseconds()) -> ok. stop_monitor(Pid, Timeout) -> ok = gen_server:call(Pid, stop, Timeout), receive {'DOWN', _, process, Pid, normal} -> ok; {'DOWN', _, process, Pid, Info} -> erlang:exit(Info) after Timeout -> erlang:exit(timeout) end. %%------------------------------------------------------------------------- %% @doc %% ===Send data to syslog without a timestamp or message_id.=== %% @end %%------------------------------------------------------------------------- -spec send(Pid :: pid(), Severity :: severity(), Data :: iodata()) -> ok. send(Pid, Severity, Data) -> send(Pid, Severity, undefined, "", Data). %%------------------------------------------------------------------------- %% @doc %% ===Send data to syslog without a message_id.=== %% @end %%------------------------------------------------------------------------- -spec send(Pid :: pid(), Severity :: severity(), Timestamp :: undefined | erlang:timestamp(), Data :: iodata()) -> ok. send(Pid, Severity, Timestamp, Data) -> send(Pid, Severity, Timestamp, "", Data). %%------------------------------------------------------------------------- %% @doc %% ===Send data to syslog.=== %% @end %%------------------------------------------------------------------------- -spec send(Pid :: pid(), Severity :: severity(), Timestamp :: undefined | erlang:timestamp(), MessageId :: message_id(), Data :: iodata()) -> ok. send(Pid, Severity, Timestamp, MessageId, Data) -> gen_server:cast(Pid, {send, Severity, Timestamp, MessageId, Data}). %%%------------------------------------------------------------------------ %%% facility and severity values are based on %%% https://tools.ietf.org/html/rfc3164#section-4.1.1 %%% https://tools.ietf.org/html/rfc5424#section-6.2.1 %%%------------------------------------------------------------------------ %%------------------------------------------------------------------------- %% @doc %% ===Get the syslog facility numerical value.=== %% @end %%------------------------------------------------------------------------- -spec facility(Facility :: facility()) -> non_neg_integer(). facility(kernel) -> 0; % kernel messages facility(user) -> 1; % user-level messages facility(mail) -> 2; % mail system facility(daemon) -> 3; % system daemons facility(auth0) -> 4; % security/authorization messages 0 facility(syslog) -> 5; % messages generated internally by syslogd facility(print) -> 6; % line printer subsystem facility(news) -> 7; % network news subsystem facility(uucp) -> 8; % UUCP subsystem facility(clock0) -> 9; % clock daemon 0 facility(auth1) -> 10; % security/authorization messages 1 facility(ftp) -> 11; % FTP daemon facility(ntp) -> 12; % NTP subsystem facility(auth2) -> 13; % log audit (security/authorization 2) facility(auth3) -> 14; % log alert (security/authorization 3) facility(clock1) -> 15; % clock daemon 1 facility(local0) -> 16; % local use 0 facility(local1) -> 17; % local use 1 facility(local2) -> 18; % local use 2 facility(local3) -> 19; % local use 3 facility(local4) -> 20; % local use 4 facility(local5) -> 21; % local use 5 facility(local6) -> 22; % local use 6 facility(local7) -> 23; % local use 7 facility(auth) -> facility(auth0); facility(authpriv) -> facility(auth1); facility(cron) -> facility(clock0); facility(kern) -> facility(kernel); facility(lpr) -> facility(print); facility(security) -> facility(auth0); facility(Facility) when is_integer(Facility), Facility >= 0 -> Facility. %%------------------------------------------------------------------------- %% @doc %% ===Test the validity of a syslog facility value.=== %% @end %%------------------------------------------------------------------------- -spec facility_valid(Facility :: facility()) -> boolean(). facility_valid(Facility) -> try facility(Facility) of _ -> true catch _:_ -> false end. %%------------------------------------------------------------------------- %% @doc %% ===Get the syslog severity numerical value.=== %% @end %%------------------------------------------------------------------------- -spec severity(Severity :: severity()) -> 0..7. severity(emergency) -> 0; % system is unusable severity(alert) -> 1; % action must be taken immediately severity(critical) -> 2; % critical conditions severity(error) -> 3; % error conditions severity(warning) -> 4; % warning conditions severity(notice) -> 5; % normal but significant condition severity(informational) -> 6; % informational messages severity(debug) -> 7; % debug-level messages severity(emerg) -> severity(emergency); severity(panic) -> severity(emergency); severity(crit) -> severity(critical); severity(err) -> severity(error); severity(warn) -> severity(warning); severity(info) -> severity(informational); severity(Severity) when is_integer(Severity), Severity >= 0, Severity =< 7 -> Severity. %%------------------------------------------------------------------------- %% @doc %% ===Test the validity of a syslog severity value.=== %% @end %%------------------------------------------------------------------------- -spec severity_valid(Severity :: severity()) -> boolean(). severity_valid(Severity) -> try severity(Severity) of _ -> true catch _:_ -> false end. %%%------------------------------------------------------------------------ %%% Callback functions from gen_server %%%------------------------------------------------------------------------ init([Transport, TransportOptions, Protocol, UTF8, Facility, AppName, Path, Host, Port, Timeout]) -> State0 = #state{transport = Transport, transport_options = TransportOptions, protocol = Protocol, utf8 = UTF8, utf8_bom = unicode:encoding_to_bom(utf8), facility = Facility, app_name = AppName, path = Path, host = Host, port = Port, timeout = Timeout}, case transport_open(State0) of {ok, State1} -> StateN = protocol_init(State1), case transport_send(<<>>, StateN) of ok -> {ok, StateN}; {error, Reason} -> {stop, Reason} end; {error, Reason} -> {stop, Reason} end. handle_call(stop, _, State) -> {stop, normal, ok, State}; handle_call(Request, _, State) -> {stop, {call, Request}, State}. handle_cast({send, Severity, Timestamp0, MessageId, Data}, State) -> TimestampN = case Timestamp0 of undefined -> os:timestamp(); {_, _, _} -> Timestamp0 end, HEADER = protocol_header(Severity, TimestampN, MessageId, State), DATA = protocol_data(State), MSG = protocol_msg(Data, State), case transport_send([HEADER, DATA, MSG], State) of ok -> {noreply, State}; {error, Reason} -> {stop, Reason, State} end; handle_cast(stop, State) -> {stop, normal, State}; handle_cast(Request, State) -> {stop, {cast, Request}, State}. handle_info({Reason, Socket}, #state{socket = Socket} = State) when Reason =:= udp_closed; Reason =:= tcp_closed; Reason =:= ssl_closed -> {stop, Reason, State#state{socket = undefined}}; handle_info({Reason, Socket}, #state{socket = Socket} = State) when Reason =:= udp_error; Reason =:= tcp_error; Reason =:= ssl_error -> {stop, Reason, State}; handle_info(Request, State) -> {stop, {info, Request}, State}. terminate(_, State) -> ok = transport_close(State), ok. code_change(_, State, _) -> {ok, State}. %%%------------------------------------------------------------------------ %%% Private functions %%%------------------------------------------------------------------------ start(Options) when is_list(Options) -> Defaults = [{transport, ?TRANSPORT_DEFAULT}, {transport_options, undefined}, {protocol, ?PROTOCOL_DEFAULT}, {utf8, ?UTF8_DEFAULT}, {facility, ?FACILITY_DEFAULT}, {app_name, undefined}, {path, "/dev/log"}, {host, {127,0,0,1}}, {port, undefined}, {timeout, ?TIMEOUT_DEFAULT}], [Transport, TransportOptionsValue, Protocol, UTF8, FacilityValue, AppName, Path, Host, PortValue, Timeout] = take_values(Defaults, Options), true = is_list(AppName) andalso is_integer(hd(AppName)), % required if Protocol =:= rfc3164 -> ok; Protocol =:= rfc5424 -> true = (length(AppName) =< 48) end, true = is_boolean(UTF8), Facility = facility(FacilityValue), true = is_integer(Timeout) andalso (Timeout > 0) andalso (Timeout =< ?TIMEOUT_MAX_ERLANG), TransportOptions = if Transport =:= local -> if TransportOptionsValue =:= undefined -> [local]; is_list(TransportOptionsValue) -> [local | TransportOptionsValue] end; Transport =:= udp -> if TransportOptionsValue =:= undefined -> []; is_list(TransportOptionsValue) -> TransportOptionsValue end; Transport =:= tcp -> if TransportOptionsValue =:= undefined -> [{send_timeout, Timeout}, {send_timeout_close, true}, {keepalive, true}, {reuseaddr, true}]; is_list(TransportOptionsValue) -> TransportOptionsValue end; Transport =:= tls -> true = is_list(TransportOptionsValue) andalso (length(TransportOptionsValue) > 0), TransportOptionsValue end, true = is_list(Path) andalso is_integer(hd(Path)), Port = if PortValue =:= undefined -> if Transport =:= local -> 0; Transport =:= udp -> 514; Transport =:= tcp -> 601; Transport =:= tls -> 6514 end; is_integer(PortValue), PortValue > 0 -> PortValue end, gen_server:start(?MODULE, [Transport, TransportOptions, Protocol, UTF8, Facility, AppName, Path, Host, Port, Timeout], []). protocol_init(#state{protocol = rfc3164} = State) -> HostnameOnly = lists:takewhile(fun(C) -> C /= $. end, hostname()), State#state{hostname = HostnameOnly, os_pid = os:getpid()}; protocol_init(#state{protocol = rfc5424} = State) -> State#state{hostname = hostname(), os_pid = os:getpid()}. protocol_header(Severity, Timestamp, MessageId, #state{transport = Transport, protocol = rfc3164, facility = Facility, app_name = APP_NAME, hostname = Hostname, os_pid = PROCID}) -> PRIVAL = (Facility bsl 3) + severity(Severity), TIMESTAMP = timestamp_rfc3164(Timestamp), HOSTNAME_SP = if Transport =:= local -> []; true -> [Hostname, ?SP] end, SP_MSGID = case MessageId of [] -> []; <<>> -> []; _ -> [?SP, MessageId] end, [$<, int_to_dec_list(PRIVAL), $>, TIMESTAMP, ?SP, HOSTNAME_SP, % extra information as MSG prefix APP_NAME, $[, PROCID, $], $:, SP_MSGID]; protocol_header(Severity, Timestamp, MessageId, #state{protocol = rfc5424, facility = Facility, app_name = APP_NAME, hostname = HOSTNAME, os_pid = PROCID}) -> PRIVAL = (Facility bsl 3) + severity(Severity), VERSION = $1, TIMESTAMP = timestamp_rfc5424(Timestamp), MSGID = case MessageId of [] -> $-; <<>> -> $-; _ -> truncate(MessageId, 32) end, [$<, int_to_dec_list(PRIVAL), $>, VERSION, ?SP, TIMESTAMP, ?SP, truncate(HOSTNAME, 255), ?SP, truncate(APP_NAME, 48), ?SP, PROCID, ?SP, MSGID]. protocol_data(#state{protocol = rfc3164}) -> []; protocol_data(#state{protocol = rfc5424}) -> STRUCTURED_DATA = $-, [?SP, STRUCTURED_DATA]. protocol_msg(Data, #state{utf8 = UTF8, utf8_bom = UTF8BOM}) -> if Data == <<>>; Data == [] -> []; UTF8 =:= true -> [?SP, UTF8BOM, Data]; UTF8 =:= false -> [?SP, Data] % ASCII end. timestamp_rfc3164({_, _, _} = Timestamp) -> {{_, DateMM, DateDD}, {TimeHH, TimeMM, TimeSS}} = calendar:now_to_local_time(Timestamp), [DateMM0, DateMM1, DateMM2] = if DateMM == 1 -> "Jan"; DateMM == 2 -> "Feb"; DateMM == 3 -> "Mar"; DateMM == 4 -> "Apr"; DateMM == 5 -> "May"; DateMM == 6 -> "Jun"; DateMM == 7 -> "Jul"; DateMM == 8 -> "Aug"; DateMM == 9 -> "Sep"; DateMM == 10 -> "Oct"; DateMM == 11 -> "Nov"; DateMM == 12 -> "Dec" end, [DateDD0, DateDD1] = int_to_dec_list(DateDD, 2, $\s), [TimeHH0, TimeHH1] = int_to_dec_list(TimeHH, 2, $0), [TimeMM0, TimeMM1] = int_to_dec_list(TimeMM, 2, $0), [TimeSS0, TimeSS1] = int_to_dec_list(TimeSS, 2, $0), [DateMM0, DateMM1, DateMM2, $\s, DateDD0, DateDD1, $\s, TimeHH0, TimeHH1, $:, TimeMM0, TimeMM1, $:, TimeSS0, TimeSS1]. timestamp_rfc5424({_, _, MicroSeconds} = Timestamp) -> {{DateYYYY, DateMM, DateDD}, {TimeHH, TimeMM, TimeSS}} = calendar:now_to_universal_time(Timestamp), [DateYYYY0, DateYYYY1, DateYYYY2, DateYYYY3] = int_to_dec_list(DateYYYY, 4, $0), [DateMM0, DateMM1] = int_to_dec_list(DateMM, 2, $0), [DateDD0, DateDD1] = int_to_dec_list(DateDD, 2, $0), [TimeHH0, TimeHH1] = int_to_dec_list(TimeHH, 2, $0), [TimeMM0, TimeMM1] = int_to_dec_list(TimeMM, 2, $0), [TimeSS0, TimeSS1] = int_to_dec_list(TimeSS, 2, $0), [MicroSeconds0, MicroSeconds1, MicroSeconds2, MicroSeconds3, MicroSeconds4, MicroSeconds5] = int_to_dec_list(MicroSeconds, 6, $0), [DateYYYY0, DateYYYY1, DateYYYY2, DateYYYY3, $-, DateMM0, DateMM1, $-, DateDD0, DateDD1, $T, TimeHH0, TimeHH1, $:, TimeMM0, TimeMM1, $:, TimeSS0, TimeSS1, $., MicroSeconds0, MicroSeconds1, MicroSeconds2, MicroSeconds3, MicroSeconds4, MicroSeconds5, $Z]. transport_open(#state{transport = Transport, transport_options = TransportOptions} = State) when Transport =:= local; Transport =:= udp -> try gen_udp:open(0, TransportOptions) of {ok, Socket} -> {ok, State#state{socket = Socket}}; {error, _} = Error -> Error catch ErrorType:ErrorReason -> {error, {ErrorType, ErrorReason}} end; transport_open(#state{transport = tcp, transport_options = TransportOptions, host = Host, port = Port, timeout = Timeout} = State) -> try gen_tcp:connect(Host, Port, TransportOptions, Timeout) of {ok, Socket} -> {ok, State#state{socket = Socket}}; {error, _} = Error -> Error catch ErrorType:ErrorReason -> {error, {ErrorType, ErrorReason}} end; transport_open(#state{transport = tls, transport_options = TransportOptions, host = Host, port = Port, timeout = Timeout} = State) -> try ssl:connect(Host, Port, TransportOptions, Timeout) of {ok, Socket} -> {ok, State#state{socket = Socket}}; {error, _} = Error -> Error catch ErrorType:ErrorReason -> {error, {ErrorType, ErrorReason}} end. transport_send(Data, #state{transport = local, path = Path, port = Port, socket = Socket}) -> gen_udp:send(Socket, {local, Path}, Port, Data); transport_send(Data, #state{transport = udp, host = Host, port = Port, socket = Socket}) -> gen_udp:send(Socket, Host, Port, Data); transport_send(Data, #state{transport = tcp, socket = Socket}) -> gen_tcp:send(Socket, Data); transport_send(Data, #state{transport = tls, socket = Socket}) -> ssl:send(Socket, Data). transport_close(#state{socket = undefined}) -> ok; transport_close(#state{transport = Transport, socket = Socket}) when Transport =:= local; Transport =:= udp -> _ = (catch gen_udp:close(Socket)), ok; transport_close(#state{transport = tcp, socket = Socket}) -> _ = (catch gen_tcp:close(Socket)), ok; transport_close(#state{transport = tls, socket = Socket}) -> _ = (catch ssl:close(Socket)), ok. hostname() -> case lists:dropwhile(fun(C) -> C /= $@ end, erlang:atom_to_list(node())) of [$@ | "nohost"] -> {ok, Hostname} = inet:gethostname(), Hostname; [$@ | FQDN] -> FQDN end. truncate(Value, N) when is_list(Value) -> lists:sublist(Value, N); truncate(Value, N) when is_binary(Value) -> case Value of <> -> ValuePrefix; _ -> Value end. take_values(DefaultList, List) when is_list(DefaultList), is_list(List) -> take_values([], DefaultList, List). take_values(Result, [], List) -> lists:reverse(Result) ++ List; take_values(Result, [{Key, Default} | DefaultList], List) -> case lists:keytake(Key, 1, List) of false -> take_values([Default | Result], DefaultList, List); {value, {Key, Value}, RemainingList} -> take_values([Value | Result], DefaultList, RemainingList) end. int_to_dec_list(I) when is_integer(I), I >= 0 -> int_to_dec_list([], I). int_to_dec_list(L, I) when I < 10 -> [int_to_dec(I) | L]; int_to_dec_list(L, I) -> int_to_dec_list([int_to_dec(I rem 10) | L], I div 10). int_to_dec_list(I, N, Char) when is_integer(I), I >= 0 -> int_to_dec_list([], I, 1, N, Char). int_to_dec_list(L, I, Count, N, Char) when I < 10 -> int_to_list_pad([int_to_dec(I) | L], N - Count, Char); int_to_dec_list(L, I, Count, N, Char) -> int_to_dec_list([int_to_dec(I rem 10) | L], I div 10, Count + 1, N, Char). int_to_list_pad(L, 0, _) -> L; int_to_list_pad(L, Count, Char) -> int_to_list_pad([Char | L], Count - 1, Char). int_to_dec(I) when 0 =< I, I =< 9 -> I + $0.