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defmodule Lithium.DMARC do
require Logger
defp select_record(records) do
filtered =
records
|> Enum.map(&String.trim/1)
|> Enum.filter(fn found_record ->
# As per Section 7.1, DMARC report authorisations also use a format of "v=DMARC1"
# We should check when we find a tag that it is not *just* a version record.
trimmed = String.replace(found_record, " ", "")
String.starts_with?(trimmed, "v=DMARC1;") and trimmed != "v=DMARC1;"
end)
case filtered do
[] ->
{:error, :nxdomain}
[record] ->
{:ok, record}
_ ->
{:error, :multiple_records}
end
end
def get_dmarc_policy(domain) do
with od <- Lithium.Util.PublicSuffix.get_domain(domain),
{:ok, records} <- Lithium.DNS.fetch_txt("_dmarc." <> od),
{:ok, record } <- select_record(records),
{:ok, policy} <- Lithium.DMARC.Parser.parse_policy(record)
do
{:ok, policy}
else
error ->
error
end
end
end
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