# Pleroma: A lightweight social networking server
# Copyright © 2017-2019 Pleroma Authors
# SPDX-License-Identifier: AGPL-3.0-only
defmodule Pleroma.Web.Salmon do
@httpoison Application.get_env(:pleroma, :httpoison)
use Bitwise
alias Pleroma.Instances
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 = """
#{doc_base64}
#{encoding}
#{alg}
#{signature}
"""
{: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
#
def send_to_user(%{info: %{salmon: salmon}}, feed, poster),
do: send_to_user(salmon, feed, poster)
def send_to_user(url, feed, poster) when is_binary(url) do
with {:ok, %{status: code}} when code in 200..299 <-
poster.(
url,
feed,
[
{"Content-Type", "application/magic-envelope+xml"},
{"referer", Pleroma.Web.Endpoint.url()}
]
) do
Instances.set_reachable(url)
Logger.debug(fn -> "Pushed to #{url}, code #{code}" end)
:ok
else
e ->
Instances.set_unreachable(url)
Logger.debug(fn -> "Pushing Salmon to #{url} failed, #{inspect(e)}" end)
:error
end
end
def send_to_user(_, _, _), do: :noop
@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 = remote_users(activity)
salmon_urls = Enum.map(remote_users, & &1.info.salmon)
reachable_salmon_urls = Instances.filter_reachable(salmon_urls)
remote_users
|> Enum.filter(&(&1.info.salmon in reachable_salmon_urls))
|> Enum.each(fn remote_user ->
Logger.debug(fn -> "Sending Salmon to #{remote_user.ap_id}" end)
Pleroma.Web.Federator.enqueue(:publish_single_salmon, {remote_user, feed, poster})
end)
end
end
def publish(%{id: id}, _, _), do: Logger.debug(fn -> "Keys missing for user #{id}" end)
end