[Minor] Some debug logging for RBL module

src/plugins/lua/rbl.lua

@@ -65,7 +65,12 @@ local function rbl_cb (task)
       if err and (err ~= 'requested record is not found' and err ~= 'no records with this name') then
         rspamd_logger.errx(task, 'error looking up %s: %s', to_resolve, err)
       end
-      if not results then return end
+      if not results then
+        rspamd_logger.debugx(task, 'DNS RESPONSE: label=%1 results=%2 error=%3 rbl=%4', to_resolve, false, err, rule['rbls'][1]['symbol'])
+        return
+      else
+        rspamd_logger.debugx(task, 'DNS RESPONSE: label=%1 results=%2 error=%3 rbl=%4', to_resolve, true, err, rule['rbls'][1]['symbol'])
+      end
 
       for _,rbl in ipairs(rule.rbls) do
         if rbl['returncodes'] == nil and rbl['symbol'] ~= nil then
@@ -75,6 +80,7 @@ local function rbl_cb (task)
         for _,result in pairs(results) do
           local ipstr = result:to_string()
           local foundrc
+          rspamd_logger.debugx(task, '%s DNS result %s', to_resolve, ipstr)
           for s,i in pairs(rbl['returncodes']) do
             if type(i) == 'string' then
               if string.find(ipstr, '^' .. i .. '$') then
@@ -110,6 +116,7 @@ local function rbl_cb (task)
   local params = {} -- indexed by rbl name
 
   local function gen_rbl_rule(to_resolve, rbl)
+    rspamd_logger.debugx(task, 'DNS REQUEST: label=%1 rbl=%2', to_resolve, rbl['symbol'])
     if not params[to_resolve] then
       local nrule = {
         to_resolve = to_resolve,