72 lines
2.3 KiB
Elixir
72 lines
2.3 KiB
Elixir
defmodule Pleroma.Web.Salmon do
|
|
use Bitwise
|
|
|
|
def decode(salmon) do
|
|
{doc, _rest} = :xmerl_scan.string(to_charlist(salmon))
|
|
|
|
{:xmlObj, :string, data} = :xmerl_xpath.string('string(//me:data[1])', doc)
|
|
{:xmlObj, :string, sig} = :xmerl_xpath.string('string(//me:sig[1])', doc)
|
|
{:xmlObj, :string, alg} = :xmerl_xpath.string('string(//me:alg[1])', doc)
|
|
{:xmlObj, :string, encoding} = :xmerl_xpath.string('string(//me:encoding[1])', doc)
|
|
{:xmlObj, :string, type} = :xmerl_xpath.string('string(//me:data[1]/@type)', doc)
|
|
|
|
{:ok, data} = Base.url_decode64(to_string(data), ignore: :whitespace)
|
|
{:ok, sig} = Base.url_decode64(to_string(sig), ignore: :whitespace)
|
|
alg = to_string(alg)
|
|
encoding = to_string(encoding)
|
|
type = to_string(type)
|
|
|
|
[data, type, encoding, alg, sig]
|
|
end
|
|
|
|
def fetch_magic_key(salmon) do
|
|
[data, _, _, _, _] = decode(salmon)
|
|
{doc, _rest} = :xmerl_scan.string(to_charlist(data))
|
|
{:xmlObj, :string, uri} = :xmerl_xpath.string('string(//author[1]/uri)', doc)
|
|
|
|
uri = to_string(uri)
|
|
base = URI.parse(uri).host
|
|
|
|
# TODO: Find out if this endpoint is mandated by the standard.
|
|
{:ok, response} = HTTPoison.get(base <> "/.well-known/webfinger", ["Accept": "application/xrd+xml"], [params: [resource: uri]])
|
|
|
|
{doc, _rest} = :xmerl_scan.string(to_charlist(response.body))
|
|
|
|
{:xmlObj, :string, magickey} = :xmerl_xpath.string('string(//Link[@rel="magic-public-key"]/@href)', doc)
|
|
"data:application/magic-public-key," <> magickey = to_string(magickey)
|
|
|
|
magickey
|
|
end
|
|
|
|
def decode_and_validate(magickey, salmon) do
|
|
[data, type, encoding, alg, sig] = decode(salmon)
|
|
|
|
signed_text = [data, type, encoding, alg]
|
|
|> Enum.map(&Base.url_encode64/1)
|
|
|> Enum.join(".")
|
|
|
|
key = decode_key(magickey)
|
|
|
|
verify = :public_key.verify(signed_text, :sha256, sig, key)
|
|
|
|
if verify do
|
|
{:ok, data}
|
|
else
|
|
:error
|
|
end
|
|
end
|
|
|
|
defp decode_key("RSA." <> magickey) do
|
|
make_integer = fn(bin) ->
|
|
list = :erlang.binary_to_list(bin)
|
|
Enum.reduce(list, 0, fn (el, acc) -> (acc <<< 8) ||| el end)
|
|
end
|
|
|
|
[modulus, exponent] = magickey
|
|
|> String.split(".")
|
|
|> Enum.map(&Base.url_decode64!/1)
|
|
|> Enum.map(make_integer)
|
|
|
|
{:RSAPublicKey, modulus, exponent}
|
|
end
|
|
end
|