# Pleroma: A lightweight social networking server # Copyright © 2017-2019 Pleroma Authors <https://pleroma.social/> # SPDX-License-Identifier: AGPL-3.0-only defmodule Pleroma.Web.Salmon do @httpoison Application.get_env(:pleroma, :httpoison) use Bitwise alias Pleroma.Web.XML alias Pleroma.Web.OStatus.ActivityRepresenter alias Pleroma.User require Logger def decode(salmon) do doc = XML.parse_document(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 with [data, _, _, _, _] <- decode(salmon), doc <- XML.parse_document(data), uri when not is_nil(uri) <- XML.string_from_xpath("/entry/author[1]/uri", doc), {:ok, public_key} <- User.get_public_key_for_ap_id(uri), magic_key <- encode_key(public_key) do {:ok, magic_key} end 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 def 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(fn n -> Base.url_decode64!(n, padding: false) end) |> Enum.map(make_integer) {:RSAPublicKey, modulus, exponent} end def encode_key({:RSAPublicKey, modulus, exponent}) do modulus_enc = :binary.encode_unsigned(modulus) |> Base.url_encode64() exponent_enc = :binary.encode_unsigned(exponent) |> Base.url_encode64() "RSA.#{modulus_enc}.#{exponent_enc}" end # Native generation of RSA keys is only available since OTP 20+ and in default build conditions # We try at compile time to generate natively an RSA key otherwise we fallback on the old way. try do _ = :public_key.generate_key({:rsa, 2048, 65537}) def generate_rsa_pem do key = :public_key.generate_key({:rsa, 2048, 65537}) entry = :public_key.pem_entry_encode(:RSAPrivateKey, key) pem = :public_key.pem_encode([entry]) |> String.trim_trailing() {:ok, pem} end rescue _ -> def generate_rsa_pem do port = Port.open({:spawn, "openssl genrsa"}, [:binary]) {:ok, pem} = receive do {^port, {:data, pem}} -> {:ok, pem} end Port.close(port) if Regex.match?(~r/RSA PRIVATE KEY/, pem) do {:ok, pem} else :error end end end def keys_from_pem(pem) do [private_key_code] = :public_key.pem_decode(pem) private_key = :public_key.pem_entry_decode(private_key_code) {:RSAPrivateKey, _, modulus, exponent, _, _, _, _, _, _, _} = private_key public_key = {:RSAPublicKey, modulus, exponent} {:ok, private_key, public_key} end def encode(private_key, doc) do type = "application/atom+xml" encoding = "base64url" alg = "RSA-SHA256" signed_text = [doc, type, encoding, alg] |> Enum.map(&Base.url_encode64/1) |> Enum.join(".") signature = signed_text |> :public_key.sign(:sha256, private_key) |> to_string |> Base.url_encode64() doc_base64 = doc |> Base.url_encode64() # Don't need proper xml building, these strings are safe to leave unescaped salmon = """ <?xml version="1.0" encoding="UTF-8"?> <me:env xmlns:me="http://salmon-protocol.org/ns/magic-env"> <me:data type="application/atom+xml">#{doc_base64}</me:data> <me:encoding>#{encoding}</me:encoding> <me:alg>#{alg}</me:alg> <me:sig>#{signature}</me:sig> </me:env> """ {:ok, salmon} end def remote_users(%{data: %{"to" => to} = data}) do to = to ++ (data["cc"] || []) to |> Enum.map(fn id -> User.get_cached_by_ap_id(id) end) |> Enum.filter(fn user -> user && !user.local end) end # push an activity to remote accounts # defp send_to_user(%{info: %{salmon: salmon}}, feed, poster), do: send_to_user(salmon, feed, poster) defp send_to_user(url, feed, poster) when is_binary(url) do with {:ok, %{status: code}} <- poster.( url, feed, [{"Content-Type", "application/magic-envelope+xml"}] ) do Logger.debug(fn -> "Pushed to #{url}, code #{code}" end) else e -> Logger.debug(fn -> "Pushing Salmon to #{url} failed, #{inspect(e)}" end) end end defp send_to_user(_, _, _), do: nil @supported_activities [ "Create", "Follow", "Like", "Announce", "Undo", "Delete" ] @doc """ Publishes an activity to remote accounts """ @spec publish(User.t(), Pleroma.Activity.t(), Pleroma.HTTP.t()) :: none def publish(user, activity, poster \\ &@httpoison.post/3) def publish(%{info: %{keys: keys}} = user, %{data: %{"type" => type}} = activity, poster) when type in @supported_activities do feed = ActivityRepresenter.to_simple_form(activity, user, true) if feed do feed = ActivityRepresenter.wrap_with_entry(feed) |> :xmerl.export_simple(:xmerl_xml) |> to_string {:ok, private, _} = keys_from_pem(keys) {:ok, feed} = encode(private, feed) remote_users(activity) |> Enum.each(fn remote_user -> Task.start(fn -> Logger.debug(fn -> "Sending Salmon to #{remote_user.ap_id}" end) send_to_user(remote_user, feed, poster) end) end) end end def publish(%{id: id}, _, _), do: Logger.debug(fn -> "Keys missing for user #{id}" end) end