# 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 @behaviour Pleroma.Web.Federator.Publisher use Bitwise alias Pleroma.Activity alias Pleroma.HTTP alias Pleroma.Instances alias Pleroma.Keys alias Pleroma.User alias Pleroma.Web.ActivityPub.Visibility alias Pleroma.Web.Federator.Publisher alias Pleroma.Web.OStatus alias Pleroma.Web.OStatus.ActivityRepresenter alias Pleroma.Web.XML 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 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(%User{id: user_id}, %{data: %{"to" => to} = data}) do cc = Map.get(data, "cc", []) bcc = data |> Map.get("bcc", []) |> Enum.reduce([], fn ap_id, bcc -> case Pleroma.List.get_by_ap_id(ap_id) do %Pleroma.List{user_id: ^user_id} = list -> {:ok, following} = Pleroma.List.get_following(list) bcc ++ Enum.map(following, & &1.ap_id) _ -> bcc end end) [to, cc, bcc] |> Enum.concat() |> Enum.map(&User.get_cached_by_ap_id/1) |> Enum.filter(fn user -> user && !user.local end) end @doc "Pushes an activity to remote account." def publish_one(%{recipient: %{info: %{salmon: salmon}}} = params), do: publish_one(Map.put(params, :recipient, salmon)) def publish_one(%{recipient: url, feed: feed} = params) when is_binary(url) do with {:ok, %{status: code}} when code in 200..299 <- HTTP.post( url, feed, [{"Content-Type", "application/magic-envelope+xml"}] ) do if !Map.has_key?(params, :unreachable_since) || params[:unreachable_since], do: Instances.set_reachable(url) Logger.debug(fn -> "Pushed to #{url}, code #{code}" end) {:ok, code} else e -> unless params[:unreachable_since], do: Instances.set_reachable(url) Logger.debug(fn -> "Pushing Salmon to #{url} failed, #{inspect(e)}" end) {:error, "Unreachable instance"} end end def publish_one(%{recipient_id: recipient_id} = params) do recipient = User.get_cached_by_id(recipient_id) params |> Map.delete(:recipient_id) |> Map.put(:recipient, recipient) |> publish_one() end def publish_one(_), do: :noop @supported_activities [ "Create", "Follow", "Like", "Announce", "Undo", "Delete" ] def is_representable?(%Activity{data: %{"type" => type}} = activity) when type in @supported_activities, do: Visibility.is_public?(activity) def is_representable?(_), do: false @doc """ Publishes an activity to remote accounts """ @spec publish(User.t(), Pleroma.Activity.t()) :: none def publish(user, activity) def publish(%{info: %{keys: keys}} = user, %{data: %{"type" => type}} = activity) 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.keys_from_pem(keys) {:ok, feed} = encode(private, feed) remote_users = remote_users(user, activity) salmon_urls = Enum.map(remote_users, & &1.info.salmon) reachable_urls_metadata = Instances.filter_reachable(salmon_urls) reachable_urls = Map.keys(reachable_urls_metadata) remote_users |> Enum.filter(&(&1.info.salmon in reachable_urls)) |> Enum.each(fn remote_user -> Logger.debug(fn -> "Sending Salmon to #{remote_user.ap_id}" end) Publisher.enqueue_one(__MODULE__, %{ recipient_id: remote_user.id, feed: feed, unreachable_since: reachable_urls_metadata[remote_user.info.salmon] }) end) end end def publish(%{id: id}, _), do: Logger.debug(fn -> "Keys missing for user #{id}" end) def gather_webfinger_links(%User{} = user) do {:ok, _private, public} = Keys.keys_from_pem(user.info.keys) magic_key = encode_key(public) [ %{"rel" => "salmon", "href" => OStatus.salmon_path(user)}, %{ "rel" => "magic-public-key", "href" => "data:application/magic-public-key,#{magic_key}" } ] end def gather_nodeinfo_protocol_names, do: [] end