-- loading our DNS library
sdns = require("libsdns")
assert(sdns)
-- loading json for logging
json = require("json")
assert(json)

local string_find = string.find

-- here is the domain we want our nameserver to answer
local domain = "abukhaleed.com"

-- a helper function
function str_contains(str, substr)
    -- checks if substr exists in str
    -- returns: True if substr exists in str else false
    -- regular expression is off for this entry
    return string_find(str, substr, 1, true) ~= nil
end

-- the TXT record for DNS-01 challenge of let's encrypt (this will change every time)
local acme_challenge = "9b89104f-8c6f-420a-bbc0-2dc966516c5f.auth.acme-dns.io."


function main(raw_data, client_info)
    -- body of the main function goes here.
    -- you can convert the raw_data to a DNS packet and decide to answer
    -- the user or not. You can also create the log string here.
    if raw_data == nil then return nil, nil end
    local err = nil
    local response = nil
    response, err = sdns.from_network(raw_data)
    if response == nil then return nil, nil end
    local question = sdns.get_question(response)
    if question == nil then return nil, nil end

    local to_print = {client_ip=client_info.ip, client_port=client_info.port,
                      client_proto=client_info.proto, 
                      question={qname=question.qname, qtype=question.qtype, qclass=question.qclass}}
    if str_contains(string.lower(question.qname), domain) then
        print(json.encode(to_print))
    end

    if not str_contains(string.lower(question.qname), domain) then
        return nil, nil
    end
        
    -- let's just dump whaterver that is not class IN
    if question.qclass ~= "IN" then return nil, nil end

    -- what is the response to A request?
    if question.qtype == "A" then
        if str_contains(string.lower(question.qname), domain) then
            local a_response = sdns.create_response_from_query(response)
            sdns.add_rr_A(a_response, {ttl=86400, rdata={ip="65.108.220.8"}, name=question.qname, section="answer"})
            sdns.set_aa(a_response, 1)
            sdns.add_rr_NS(a_response, {ttl=86400, rdata={nsname='ns1.tmdhosting114.eu'}, name=question.qname, section="authority"})
            sdns.add_rr_NS(a_response, {ttl=86400, rdata={nsname='ns2.tmdhosting114.eu'}, name=question.qname, section="authority"})
            local a_response_raw = sdns.to_network(a_response)
            return nil, a_response_raw
        end
    end

    -- answer to NS queries
    if question.qtype == "NS" then
        if str_contains(string.lower(question.qname), domain) then
            local ns_response = sdns.create_response_from_query(response)
            sdns.add_rr_NS(ns_response, {ttl=86400, rdata={nsname='ns1.tmdhosting114.eu'}, name=question.qname, section="answer"})
            sdns.add_rr_NS(ns_response, {ttl=86400, rdata={nsname='ns2.tmdhosting114.eu'}, name=question.qname, section="answer"})
            sdns.set_aa(ns_response, 1)
            sdns.add_rr_A(ns_response, {ttl=86400, rdata={ip="65.108.220.8"}, name=question.qname, section="additional"})
            local ns_response_raw = sdns.to_network(ns_response)
            return nil, ns_response_raw
        end
    end
            
    -- for DNS-01 acme challenge
    if question.qtype == 'TXT' then
        if str_contains(string.lower(question.qname), domain) then
            local txt_response = sdns.create_response_from_query(response)
            sdns.add_rr_TXT(txt_response, {ttl=1800, rdata={txtdata=acme_challenge}, name=question.qname, section="answer"})
            sdns.set_aa(txt_response, 1)
            local txt_response_raw = sdns.to_network(txt_response)
            return nil, txt_response_raw
        end
    end

    -- return noerror with soa for whatever other queries for this domain
    if str_contains(string.lower(question.qname), domain) then
        local soa_response = sdns.create_response_from_query(response)
        sdns.add_rr_SOA(soa_response, {ttl=86400, rdata={mname="ns1.tmdhosting114.eu", rname="geek4arab.gmail.com",
                                                   refresh=3600, retry=1800, expire=1800, minimum=1800,serial=2026030710},
                                                   section="authority", name=question.qname})
        sdns.set_aa(soa_response, 1)
        local soa_response_raw = sdns.to_network(soa_response)
        return nil, soa_response_raw
    end

    -- no response (drop packet) in other cases.
    return nil, nil
end

local domain = "abukhaleed.com"

local domain = "beuy.ch"