block.lua

--[[
This script reads a list of domains we want to block from a file and redirects
all A or AAAA requsts to a "sorry page".
--]]

-- returns true if the given file exists
function fileExists(file)
  local f = io.open(file, "rb")
  if f then
    f:close()
  end
  return f ~= nil
end

-- loads contents of a file line by line into the given table
function loadFile(filename, list)
  if fileExists(filename) then
    for line in io.lines(filename) do
      list:add(line)
    end
    pdnslog("Lua script: " .. filename .. " successfully loaded", pdns.loglevels.Notice)
  else
    pdnslog("Lua script: could not open file " .. filename, pdns.loglevels.Warning)
  end
end


-- this funciton is hooked before resolving starts
function preresolve(dq)
  -- check blocklist
  if blocklist:check(dq.qname) then
    if dq.qtype == pdns.A or dq.qtype == pdns.ANY then
      dq:addAnswer(pdns.A, "192.0.2.1")
    end

    if dq.qtype == pdns.AAAA or dq.qtype == pdns.ANY then
      dq:addAnswer(pdns.AAAA, "2001:db8::1")
    end

    blocklist_metric:inc()
    return true
  end

  -- default, do not rewrite this response
  return false
end


-- import court mandated blocklist
blocklist=newDS()
loadFile("/etc/pdns-recursor/block.list", blocklist)

-- get metrics
blocklist_metric = getMetric("blocklist_hits")