ciro.lua

---
--- Domain blacklist/override - LUA evaluation script
---
--- v0.1 (20141025) - Ciro Iriarte <ciro.iriarte@gmail.com>
--- - First release
--- v0.2 (20141029) - Ciro Iriarte <ciro.iriarte@gmail.com>
--- - Added verification for *.arpa requests, exit inmediatly
--- - Added support for "domain ending in", with *.badboy.com
--- - ToDo: cleanup duplicated code?
--- v0.3 (20141215) - Ciro Iriarte <ciro.iriarte@gmail.com>
--- - Fixed a bug with character evaluation that allowed an infinite loop
--- v0.4 (20141217) - Ciro Iriarte <ciro.iriarte@gmail.com>
--- - Limit loop to 127 iterations (max allowed levels on a domain), protects us from infinite loop scenarios
--- - Open CDB file just once. This will require a script reload on update.
--- - Normalize queries to lowercase

function endswith(s, send)
        return #s >= #send and s:find(send, #s-#send+1, true) and true or false
end

function preresolve ( remoteip, domain, qtype )

        domain = string.lower( domain )
        orig_domain = domain

        if endswith (domain,".arpa.") then
                return -1, {}
        end

        resp=db:get(domain)

        if resp == nil then
                guard = 128
                while domain ~= "" and guard > 0
                do
                        guard = guard-1
                        domain = domain:gsub("[^%.]*%.(.*)", "%1")
                        ---print ("Looking for = *." .. domain)
                        resp=db:get("*." .. domain)
                        if resp ~= nil then
                                ---print ("++> Got match")

                                rtype, rvalue = resp:match("([^,]+),([^,]+)")
                                ---print("Tipo: " .. rtype .. "| Valor: " .. rvalue)

                                ret={
                                        {qtype=rtype, ttl=1, place="1", content=rvalue},
                                }

                                if tonumber(rtype) == pdns.CNAME then
                                        return "followCNAMERecords", 0, ret
                                else
                                        return 0, ret
                                end
                        else
                                ---print ("--> didn't get match")
                        end
                end

                if guard == 0 then
                        pdnslog("Got stuck at '" .. domain .. "' when called with '" .. orig_domain .. "'", pdns.loglevels.Warning)
                        ---print("Got stuck at '" .. domain .. "' when called with '" .. orig_domain .. "'")
                end

                return -1, {}
        else

                rtype, rvalue = resp:match("([^,]+),([^,]+)")
                ---print("Tipo: " .. rtype .. "| Valor: " .. rvalue)
                ret={
                        {qtype=rtype, ttl=1, place="1", content=rvalue},
                }

                if tonumber(rtype) == pdns.CNAME then
                        return "followCNAMERecords", 0, ret
                else
                        return 0, ret
                end
        end

end

cdb = require("cdb")
db = assert(cdb.open("/etc/powerdns/blacklist.cdb"))
--preresolve ( "10.1.1.1","pelota.twi-tter.com","TXT")