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lib/wechat/plugs/check_url_signature.ex
defmodule Wechat.Plugs.CheckUrlSignature do
@moduledoc """
Plug to check url signature.
"""
import Plug.Conn
def init(opts) do
Keyword.merge(opts, token: Wechat.config[:token])
end
def call(conn = %Plug.Conn{params: params}, [token: token]) do
%{"timestamp" => timestamp, "nonce" => nonce,
"signature" => signature} = params
my_signature = sign [token, timestamp, nonce]
case my_signature == signature do
true ->
conn
false ->
conn
|> send_resp(400, "")
|> halt
end
end
defp sign(args) do
args
|> Enum.sort
|> Enum.join
|> sha1
end
defp sha1(str) do
:crypto.hash(:sha, str)
|> Base.encode16(case: :lower)
end
end