ejabberd

%%%----------------------------------------------------------------------
%%% File    : ejabberd_commands.erl
%%% Author  : Badlop <badlop@process-one.net>
%%% Purpose : Management of ejabberd commands
%%% Created : 20 May 2008 by Badlop <badlop@process-one.net>
%%%
%%%
%%% ejabberd, Copyright (C) 2002-2020   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.
%%%
%%%----------------------------------------------------------------------

%%% @headerfile "ejabberd_commands.hrl"

%%% @doc Management of ejabberd commands.
%%%
%%% An ejabberd command is an abstract function identified by a name,
%%% with a defined number and type of calling arguments and type of
%%% result, that can be defined in any Erlang module and executed
%%% using any valid frontend.
%%%
%%%
%%% == Define a new ejabberd command ==
%%%
%%% ejabberd commands can be defined and registered in
%%% any Erlang module.
%%%
%%% Some commands are procedures; and their purpose is to perform an
%%% action in the server, so the command result is only some result
%%% code or result tuple.  Other commands are inspectors, and their
%%% purpose is to gather some information about the server and return
%%% a detailed response: it can be integer, string, atom, tuple, list
%%% or a mix of those ones.
%%%
%%% The arguments and result of an ejabberd command are strictly
%%% defined.  The number and format of the arguments provided when
%%% calling an ejabberd command must match the definition of that
%%% command.  The format of the result provided by an ejabberd command
%%% must be exactly its definition. For example, if a command is said
%%% to return an integer, it must always return an integer (except in
%%% case of a crash).
%%%
%%% If you are developing an Erlang module that will run inside
%%% ejabberd and you want to provide a new ejabberd command to
%%% administer some task related to your module, you only need to:
%%% implement a function, define the command, and register it.
%%%
%%%
%%% === Define a new ejabberd command ===
%%%
%%% An ejabberd command is defined using the Erlang record
%%% 'ejabberd_commands'.  This record has several elements that you
%%% must define. Note that 'tags', 'desc' and 'longdesc' are optional.
%%%
%%% For example let's define an ejabberd command 'pow' that gets the
%%% integers 'base' and 'exponent'. Its result will be an integer
%%% 'power':
%%%
%%% <pre>#ejabberd_commands{name = pow, tags = [test],
%%%                 desc = "Return the power of base for exponent",
%%%                 longdesc = "This is an example command. The formula is:\n"
%%%                 "  power = base ^ exponent",
%%%                 module = ?MODULE, function = pow,
%%%                 args = [{base, integer}, {exponent, integer}],
%%%                 result = {power, integer}}</pre>
%%%
%%%
%%% === Implement the function associated to the command ===
%%%
%%% Now implement a function in your module that matches the arguments
%%% and result of the ejabberd command.
%%%
%%% For example the function calc_power gets two integers Base and
%%% Exponent. It calculates the power and rounds to an integer:
%%%
%%% <pre>calc_power(Base, Exponent) ->
%%%    PowFloat = math:pow(Base, Exponent),
%%%    round(PowFloat).</pre>
%%%
%%% Since this function will be called by ejabberd_commands, it must
%%% be exported.
%%% Add to your module:
%%% <pre>-export([calc_power/2]).</pre>
%%%
%%% Only some types of result formats are allowed.
%%% If the format is defined as 'rescode', then your function must return:
%%%   ok | true | atom()
%%% where the atoms ok and true as considered positive answers,
%%% and any other response atom is considered negative.
%%%
%%% If the format is defined as 'restuple', then the command must return:
%%%   {rescode(), string()}
%%%
%%% If the format is defined as '{list, something()}', then the command
%%% must return a list of something().
%%%
%%%
%%% === Register the command ===
%%%
%%% Define this function and put inside the #ejabberd_command you
%%% defined in the beginning:
%%%
%%% <pre>commands() ->
%%%    [
%%%
%%%    ].</pre>
%%%
%%% You need to include this header file in order to use the record:
%%%
%%% <pre>-include("ejabberd_commands.hrl").</pre>
%%%
%%% When your module is initialized or started, register your commands:
%%%
%%% <pre>ejabberd_commands:register_commands(commands()),</pre>
%%%
%%% And when your module is stopped, unregister your commands:
%%%
%%% <pre>ejabberd_commands:unregister_commands(commands()),</pre>
%%%
%%% That's all! Now when your module is started, the command will be
%%% registered and any frontend can access it. For example:
%%%
%%% <pre>$ ejabberdctl help pow
%%%
%%%   Command Name: pow
%%%
%%%   Arguments: base::integer
%%%              exponent::integer
%%%
%%%   Returns: power::integer
%%%
%%%   Tags: test
%%%
%%%   Description: Return the power of base for exponent
%%%
%%% This is an example command. The formula is:
%%%  power = base ^ exponent
%%%
%%% $ ejabberdctl pow 3 4
%%% 81
%%% </pre>
%%%
%%%
%%% == Execute an ejabberd command ==
%%%
%%% ejabberd commands are mean to be executed using any valid
%%% frontend.  An ejabberd commands is implemented in a regular Erlang
%%% function, so it is also possible to execute this function in any
%%% Erlang module, without dealing with the associated ejabberd
%%% commands.
%%%
%%%
%%% == Frontend to ejabberd commands ==
%%%
%%% Currently there are two frontends to ejabberd commands: the shell
%%% script {@link ejabberd_ctl. ejabberdctl}, and the XML-RPC server
%%% ejabberd_xmlrpc.
%%%
%%%
%%% === ejabberdctl as a frontend to ejabberd commands ===
%%%
%%% It is possible to use ejabberdctl to get documentation of any
%%% command. But ejabberdctl does not support all the argument types
%%% allowed in ejabberd commands, so there are some ejabberd commands
%%% that cannot be executed using ejabberdctl.
%%%
%%% Also note that the ejabberdctl shell administration script also
%%% manages ejabberdctl commands, which are unrelated to ejabberd
%%% commands and can only be executed using ejabberdctl.
%%%
%%%
%%% === ejabberd_xmlrpc as a frontend to ejabberd commands ===
%%%
%%% ejabberd_xmlrpc provides an XML-RPC server to execute ejabberd commands.
%%% ejabberd_xmlrpc is a contributed module published in ejabberd-modules SVN.
%%%
%%% Since ejabberd_xmlrpc does not provide any method to get documentation
%%% of the ejabberd commands, please use ejabberdctl to know which
%%% commands are available, and their usage.
%%%
%%% The number and format of the arguments provided when calling an
%%% ejabberd command must match the definition of that command. Please
%%% make sure the XML-RPC call provides the required arguments, with
%%% the specified format. The order of the arguments in an XML-RPC
%%% call is not important, because all the data is tagged and will be
%%% correctly prepared by ejabberd_xmlrpc before executing the ejabberd
%%% command.

%%% TODO: consider this feature:
%%% All commands are caught. If an error happens, return the restuple:
%%%   {error, flattened error string}
%%% This means that ecomm call APIs (ejabberd_ctl, ejabberd_xmlrpc)
%%% need to allows this. And ejabberd_xmlrpc must be prepared to
%%% handle such an unexpected response.


-module(ejabberd_commands).
-author('badlop@process-one.net').

-behaviour(gen_server).

-define(DEFAULT_VERSION, 1000000).

-export([start_link/0,
	 list_commands/0,
	 list_commands/1,
	 get_command_format/1,
	 get_command_format/2,
	 get_command_format/3,
	 get_command_definition/1,
	 get_command_definition/2,
	 get_tags_commands/0,
	 get_tags_commands/1,
	 register_commands/1,
	 unregister_commands/1,
	 get_commands_spec/0,
	 get_commands_definition/0,
	 get_commands_definition/1,
	 execute_command2/3,
	 execute_command2/4]).
%% gen_server callbacks
-export([init/1, handle_call/3, handle_cast/2, handle_info/2,
	 terminate/2, code_change/3]).

-include("ejabberd_commands.hrl").
-include("logger.hrl").
-include_lib("stdlib/include/ms_transform.hrl").

-define(POLICY_ACCESS, '$policy').

-type auth() :: {binary(), binary(), binary() | {oauth, binary()}, boolean()} | map().

-record(state, {}).

get_commands_spec() ->
    [
        #ejabberd_commands{name = gen_html_doc_for_commands, tags = [documentation],
                           desc = "Generates html documentation for ejabberd_commands",
                           module = ejabberd_commands_doc, function = generate_html_output,
                           args = [{file, binary}, {regexp, binary}, {examples, binary}],
                           result = {res, rescode},
                           args_desc = ["Path to file where generated "
                                        "documentation should be stored",
                                        "Regexp matching names of commands or modules "
                                        "that will be included inside generated document",
                                        "Comma separated list of languages (chosen from java, perl, xmlrpc, json)"
                                        "that will have example invocation include in markdown document"],
                           result_desc = "0 if command failed, 1 when succeeded",
                           args_example = ["/home/me/docs/api.html", "mod_admin", "java,json"],
                           result_example = ok},
        #ejabberd_commands{name = gen_markdown_doc_for_commands, tags = [documentation],
                           desc = "Generates markdown documentation for ejabberd_commands",
                           module = ejabberd_commands_doc, function = generate_md_output,
                           args = [{file, binary}, {regexp, binary}, {examples, binary}],
                           result = {res, rescode},
                           args_desc = ["Path to file where generated "
                                        "documentation should be stored",
                                        "Regexp matching names of commands or modules "
                                        "that will be included inside generated document",
                                        "Comma separated list of languages (chosen from java, perl, xmlrpc, json)"
                                        "that will have example invocation include in markdown document"],
                           result_desc = "0 if command failed, 1 when succeeded",
                           args_example = ["/home/me/docs/api.html", "mod_admin", "java,json"],
                           result_example = ok}].

start_link() ->
    gen_server:start_link({local, ?MODULE}, ?MODULE, [], []).

init([]) ->
    try mnesia:transform_table(ejabberd_commands, ignore,
			       record_info(fields, ejabberd_commands))
    catch exit:{aborted, {no_exists, _}} -> ok
    end,
    ejabberd_mnesia:create(?MODULE, ejabberd_commands,
                        [{ram_copies, [node()]},
                         {local_content, true},
                         {attributes, record_info(fields, ejabberd_commands)},
                         {type, bag}]),
    register_commands(get_commands_spec()),
    {ok, #state{}}.

handle_call(Request, From, State) ->
    ?WARNING_MSG("Unexpected call from ~p: ~p", [From, Request]),
    {noreply, State}.

handle_cast(Msg, State) ->
    ?WARNING_MSG("Unexpected cast: ~p", [Msg]),
    {noreply, State}.

handle_info(Info, State) ->
    ?WARNING_MSG("Unexpected info: ~p", [Info]),
    {noreply, State}.

terminate(_Reason, _State) ->
    ok.

code_change(_OldVsn, State, _Extra) ->
    {ok, State}.

-spec register_commands([ejabberd_commands()]) -> ok.

%% @doc Register ejabberd commands.
%% If a command is already registered, a warning is printed and the
%% old command is preserved.
%% A registered command is not directly available to be called through
%% ejabberd ReST API. It need to be exposed to be available through API.
register_commands(Commands) ->
    lists:foreach(
      fun(Command) ->
              %% XXX check if command exists
              mnesia:dirty_write(Command)
              %% ?DEBUG("This command is already defined:~n~p", [Command])
      end,
      Commands),
    ejabberd_access_permissions:invalidate(),
    ok.

-spec unregister_commands([ejabberd_commands()]) -> ok.

%% @doc Unregister ejabberd commands.
unregister_commands(Commands) ->
    lists:foreach(
      fun(Command) ->
	      mnesia:dirty_delete_object(Command)
      end,
      Commands),
    ejabberd_access_permissions:invalidate().

-spec list_commands() -> [{atom(), [aterm()], string()}].

%% @doc Get a list of all the available commands, arguments and description.
list_commands() ->
    list_commands(?DEFAULT_VERSION).

-spec list_commands(integer()) -> [{atom(), [aterm()], string()}].

%% @doc Get a list of all the available commands, arguments and
%% description in a given API version.
list_commands(Version) ->
    Commands = get_commands_definition(Version),
    [{Name, Args, Desc} || #ejabberd_commands{name = Name,
                                              args = Args,
                                              desc = Desc} <- Commands].

-spec get_command_format(atom()) -> {[aterm()], [{atom(),atom()}], rterm()}.

%% @doc Get the format of arguments and result of a command.
get_command_format(Name) ->
    get_command_format(Name, noauth, ?DEFAULT_VERSION).
get_command_format(Name, Version) when is_integer(Version) ->
    get_command_format(Name, noauth, Version);
get_command_format(Name, Auth)  ->
    get_command_format(Name, Auth, ?DEFAULT_VERSION).

-spec get_command_format(atom(), noauth | admin | auth(), integer()) -> {[aterm()], [{atom(),atom()}], rterm()}.
get_command_format(Name, Auth, Version) ->
    Admin = is_admin(Name, Auth, #{}),
    #ejabberd_commands{args = Args,
		       result = Result,
		       args_rename = Rename,
                       policy = Policy} =
        get_command_definition(Name, Version),
    case Policy of
        user when Admin;
                  Auth == noauth ->
            {[{user, binary}, {host, binary} | Args], Rename, Result};
        _ ->
            {Args, Rename, Result}
    end.

-spec get_command_definition(atom()) -> ejabberd_commands().

%% @doc Get the definition record of a command.
get_command_definition(Name) ->
    get_command_definition(Name, ?DEFAULT_VERSION).

-spec get_command_definition(atom(), integer()) -> ejabberd_commands().

%% @doc Get the definition record of a command in a given API version.
get_command_definition(Name, Version) ->
    case lists:reverse(
           lists:sort(
             mnesia:dirty_select(
               ejabberd_commands,
               ets:fun2ms(
                 fun(#ejabberd_commands{name = N, version = V} = C)
                       when N == Name, V =< Version ->
                         {V, C}
                 end)))) of
        [{_, Command} | _ ] -> Command;
        _E -> throw({error, unknown_command})
    end.

get_commands_definition() ->
    get_commands_definition(?DEFAULT_VERSION).

-spec get_commands_definition(integer()) -> [ejabberd_commands()].

% @doc Returns all commands for a given API version
get_commands_definition(Version) ->
    L = lists:reverse(
          lists:sort(
            mnesia:dirty_select(
              ejabberd_commands,
              ets:fun2ms(
                fun(#ejabberd_commands{name = Name, version = V} = C)
                      when V =< Version ->
                        {Name, V, C}
                end)))),
    F = fun({_Name, _V, Command}, []) ->
                [Command];
           ({Name, _V, _Command}, [#ejabberd_commands{name=Name}|_T] = Acc) ->
                Acc;
           ({_Name, _V, Command}, Acc) -> [Command | Acc]
        end,
    lists:foldl(F, [], L).

execute_command2(Name, Arguments, CallerInfo) ->
    execute_command2(Name, Arguments, CallerInfo, ?DEFAULT_VERSION).

execute_command2(Name, Arguments, CallerInfo, Version) ->
    Command = get_command_definition(Name, Version),
    case ejabberd_access_permissions:can_access(Name, CallerInfo) of
	allow ->
	    do_execute_command(Command, Arguments);
	_ ->
	    throw({error, access_rules_unauthorized})
    end.


do_execute_command(Command, Arguments) ->
    Module = Command#ejabberd_commands.module,
    Function = Command#ejabberd_commands.function,
    ?DEBUG("Executing command ~p:~p with Args=~p", [Module, Function, Arguments]),
    ejabberd_hooks:run(api_call, [Module, Function, Arguments]),
    apply(Module, Function, Arguments).

-spec get_tags_commands() -> [{string(), [string()]}].

%% @spec () -> [{Tag::string(), [CommandName::string()]}]
%% @doc Get all the tags and associated commands.
get_tags_commands() ->
    get_tags_commands(?DEFAULT_VERSION).

-spec get_tags_commands(integer()) -> [{string(), [string()]}].

%% @spec (integer) -> [{Tag::string(), [CommandName::string()]}]
%% @doc Get all the tags and associated commands in a given API version
get_tags_commands(Version) ->
    CommandTags = [{Name, Tags} ||
		      #ejabberd_commands{name = Name, tags = Tags}
			  <- get_commands_definition(Version)],
    Dict = lists:foldl(
	     fun({CommandNameAtom, CTags}, D) ->
		     CommandName = atom_to_list(CommandNameAtom),
		     case CTags of
			 [] ->
			     orddict:append("untagged", CommandName, D);
			 _ ->
			     lists:foldl(
			       fun(TagAtom, DD) ->
				       Tag = atom_to_list(TagAtom),
				       orddict:append(Tag, CommandName, DD)
			       end,
			       D,
			       CTags)
		     end
	     end,
	     orddict:new(),
	     CommandTags),
    orddict:to_list(Dict).

%% -----------------------------
%% Access verification
%% -----------------------------
-spec is_admin(atom(), admin | noauth | auth(), map()) -> boolean().
is_admin(_Name, admin, _Extra) ->
    true;
is_admin(_Name, {_User, _Server, _, false}, _Extra) ->
    false;
is_admin(_Name, Map, _extra) when is_map(Map) ->
    true;
is_admin(_Name, _Auth, _Extra) ->
    false.