moduleapi: Add 'peek' to :may() and new :could() helper to suppress logging

The current method logs scary "access denied" messages on failure - this is
generally very useful when debugging access control stuff, but in some cases
the call is simply a check to see if someone *could* perform an action, even
if they haven't requested it yet. One example is determining whether to show
the user as an admin in disco.

The 'peek' parameter, if true, will suppress such logging.

The :could() method is just a simple helper that can make the calling code a
bit more readable (suggested by Zash).

1 files changed, 19 insertions, 7 deletions

diff --git a/core/moduleapi.lua b/core/moduleapi.lua
index 18452e2b..00b2ae16 100644
--- a/core/moduleapi.lua
+++ b/core/moduleapi.lua
@@ -626,7 +626,11 @@ function api:default_permissions(role_name, permissions)
 	end
 end
 
-function api:may(action, context)
+function api:could(action, context)
+	return self:may(action, context, true);
+end
+
+function api:may(action, context, peek)
 	if action:byte(1) == 58 then -- action begins with ':'
 		action = self.name..action; -- prepend module name
 	end
@@ -639,12 +643,16 @@ function api:may(action, context)
 			role = hosts[self.host].authz.get_jid_role(context);
 		end
 		if not role then
-			self:log("debug", "Access denied: JID <%s> may not %s (no role found)", context, action);
+			if not peek then
+				self:log("debug", "Access denied: JID <%s> may not %s (no role found)", context, action);
+			end
 			return false;
 		end
 		local permit = role:may(action);
 		if not permit then
-			self:log("debug", "Access denied: JID <%s> may not %s (not permitted by role %s)", context, action, role.name);
+			if not peek then
+				self:log("debug", "Access denied: JID <%s> may not %s (not permitted by role %s)", context, action, role.name);
+			end
 		end
 		return permit;
 	end
@@ -656,11 +664,13 @@ function api:may(action, context)
 	if session.type == "c2s" and session.host == self.host then
 		local role = session.role;
 		if not role then
-			self:log("warn", "Access denied: session %s has no role assigned");
+			if not peek then
+				self:log("warn", "Access denied: session %s has no role assigned");
+			end
 			return false;
 		end
 		local permit = role:may(action, context);
-		if not permit then
+		if not permit and not peek then
 			self:log("debug", "Access denied: session %s (%s) may not %s (not permitted by role %s)",
 				session.id, session.full_jid, action, role.name
 			);
@@ -670,11 +680,13 @@ function api:may(action, context)
 		local actor_jid = context.stanza.attr.from;
 		local role = hosts[self.host].authz.get_jid_role(actor_jid);
 		if not role then
-			self:log("debug", "Access denied: JID <%s> may not %s (no role found)", actor_jid, action);
+			if not peek then
+				self:log("debug", "Access denied: JID <%s> may not %s (no role found)", actor_jid, action);
+			end
 			return false;
 		end
 		local permit = role:may(action, context);
-		if not permit then
+		if not permit and not peek then
 			self:log("debug", "Access denied: JID <%s> may not %s (not permitted by role %s)", actor_jid, action, role.name);
 		end
 		return permit;