Added support for captcha feature disability (EJAB-895)

If the option captcha_cmd is set but captcha can't be created:
* show critical error at server start
* hide captcha option in room configuration form
* don't require occupants to fill captcha

SVN Revision: 2101

src/ejabberd_captcha.erl

@@ -17,7 +17,7 @@
 	 terminate/2, code_change/3]).
 
 -export([create_captcha/6, build_captcha_html/2, check_captcha/2,
-	 process_reply/1, process/2]).
+	 process_reply/1, process/2, is_feature_available/0]).
 
 -include("jlib.hrl").
 -include("ejabberd.hrl").
@@ -227,6 +227,7 @@ init([]) ->
 			[{ram_copies, [node()]},
 			 {attributes, record_info(fields, captcha)}]),
     mnesia:add_table_copy(captcha, node(), ram_copies),
+    check_captcha_setup(),
     {ok, #state{}}.
 
 handle_call(_Request, _From, State) ->
@@ -359,3 +360,28 @@ return(Port, TRef, Result) ->
     end,
     catch port_close(Port),
     Result.
+
+is_feature_enabled() ->
+    case get_prog_name() of
+	"" -> false;
+	Prog when is_list(Prog) -> true
+    end.
+
+is_feature_available() ->
+    case is_feature_enabled() of
+	false -> false;
+	true ->
+	    case create_image() of
+		{ok, _, _, _} -> true;
+		_Error -> false
+	    end
+    end.
+
+check_captcha_setup() ->
+    case is_feature_enabled() andalso not is_feature_available() of
+	true ->
+	    ?CRITICAL_MSG("Captcha is enabled in the option captcha_cmd, "
+			  "but it can't generate images.", []);
+	false ->
+	    ok
+    end.

src/mod_muc/mod_muc_room.erl

@@ -1620,7 +1620,8 @@ check_password(_ServiceAffiliation, Affiliation, Els, From, StateData) ->
     end.
 
 check_captcha(Affiliation, From, StateData) ->
-    case (StateData#state.config)#config.captcha_protected of
+    case (StateData#state.config)#config.captcha_protected
+	andalso ejabberd_captcha:is_feature_available() of
 	true when Affiliation == none ->
 	    case ?DICT:find(From, StateData#state.robots) of
 		{ok, passed} ->
@@ -2838,9 +2839,6 @@ get_config(Lang, StateData, From) ->
 	 ?BOOLXFIELD("Make room members-only",
 		     "muc#roomconfig_membersonly",
 		     Config#config.members_only),
-	 ?BOOLXFIELD("Make room captcha protected",
-		     "captcha_protected",
-		     Config#config.captcha_protected),
 	 ?BOOLXFIELD("Make room moderated",
 		     "muc#roomconfig_moderatedroom",
 		     Config#config.moderated),
@@ -2866,6 +2864,13 @@ get_config(Lang, StateData, From) ->
 		     "muc#roomconfig_allowvisitornickchange",
 		     Config#config.allow_visitor_nickchange)
 	] ++
+	case ejabberd_captcha:is_feature_available() of
+	    true ->
+	        [?BOOLXFIELD("Make room captcha protected",
+			     "captcha_protected",
+			     Config#config.captcha_protected)];
+	    false -> []
+	end ++
 	case mod_muc_log:check_access_log(
 	       StateData#state.server_host, From) of
 	    allow ->