git.squeep.com Git - akkoma/blob - lib/pleroma/web/salmon/salmon.ex

   1 defmodule Pleroma.Web.Salmon do
   2   @httpoison Application.get_env(:pleroma, :httpoison)
   3
   4   use Bitwise
   5   alias Pleroma.Web.XML
   6   alias Pleroma.Web.OStatus.ActivityRepresenter
   7   alias Pleroma.User
   8   require Logger
   9
  10   def decode(salmon) do
  11     doc = XML.parse_document(salmon)
  12
  13     {:xmlObj, :string, data} = :xmerl_xpath.string('string(//me:data[1])', doc)
  14     {:xmlObj, :string, sig} = :xmerl_xpath.string('string(//me:sig[1])', doc)
  15     {:xmlObj, :string, alg} = :xmerl_xpath.string('string(//me:alg[1])', doc)
  16     {:xmlObj, :string, encoding} = :xmerl_xpath.string('string(//me:encoding[1])', doc)
  17     {:xmlObj, :string, type} = :xmerl_xpath.string('string(//me:data[1]/@type)', doc)
  18
  19     {:ok, data} = Base.url_decode64(to_string(data), ignore: :whitespace)
  20     {:ok, sig} = Base.url_decode64(to_string(sig), ignore: :whitespace)
  21     alg = to_string(alg)
  22     encoding = to_string(encoding)
  23     type = to_string(type)
  24
  25     [data, type, encoding, alg, sig]
  26   end
  27
  28   def fetch_magic_key(salmon) do
  29     with [data, _, _, _, _] <- decode(salmon),
  30          doc <- XML.parse_document(data),
  31          uri when not is_nil(uri) <- XML.string_from_xpath("/entry/author[1]/uri", doc),
  32          {:ok, %{info: %{"magic_key" => magic_key}}} <- Pleroma.Web.OStatus.find_or_make_user(uri) do
  33       {:ok, magic_key}
  34     end
  35   end
  36
  37   def decode_and_validate(magickey, salmon) do
  38     [data, type, encoding, alg, sig] = decode(salmon)
  39
  40     signed_text = [data, type, encoding, alg]
  41     |> Enum.map(&Base.url_encode64/1)
  42     |> Enum.join(".")
  43
  44     key = decode_key(magickey)
  45
  46     verify = :public_key.verify(signed_text, :sha256, sig, key)
  47
  48     if verify do
  49       {:ok, data}
  50     else
  51       :error
  52     end
  53   end
  54
  55   def decode_key("RSA." <> magickey) do
  56     make_integer = fn(bin) ->
  57       list = :erlang.binary_to_list(bin)
  58       Enum.reduce(list, 0, fn (el, acc) -> (acc <<< 8) ||| el end)
  59     end
  60
  61     [modulus, exponent] = magickey
  62     |> String.split(".")
  63     |> Enum.map(fn (n) -> Base.url_decode64!(n, padding: false) end)
  64     |> Enum.map(make_integer)
  65
  66     {:RSAPublicKey, modulus, exponent}
  67   end
  68
  69   def encode_key({:RSAPublicKey, modulus, exponent}) do
  70     modulus_enc = :binary.encode_unsigned(modulus) |> Base.url_encode64
  71     exponent_enc = :binary.encode_unsigned(exponent) |> Base.url_encode64
  72
  73     "RSA.#{modulus_enc}.#{exponent_enc}"
  74   end
  75
  76   # Native generation of RSA keys is only available since OTP 20+ and in default build conditions
  77   # We try at compile time to generate natively an RSA key otherwise we fallback on the old way.
  78   try do
  79     _ = :public_key.generate_key({:rsa, 2048, 65537})
  80     def generate_rsa_pem do
  81       key = :public_key.generate_key({:rsa, 2048, 65537})
  82       entry = :public_key.pem_entry_encode(:RSAPrivateKey, key)
  83       pem = :public_key.pem_encode([entry]) |> String.trim_trailing
  84       {:ok, pem}
  85     end
  86   rescue
  87     _ ->
  88       def generate_rsa_pem do
  89         port = Port.open({:spawn, "openssl genrsa"}, [:binary])
  90         {:ok, pem} = receive do
  91           {^port, {:data, pem}} -> {:ok, pem}
  92         end
  93         Port.close(port)
  94         if Regex.match?(~r/RSA PRIVATE KEY/, pem) do
  95           {:ok, pem}
  96         else
  97           :error
  98         end
  99       end
 100   end
 101
 102   def keys_from_pem(pem) do
 103     [private_key_code] = :public_key.pem_decode(pem)
 104     private_key = :public_key.pem_entry_decode(private_key_code)
 105     {:RSAPrivateKey, _, modulus, exponent, _, _, _, _, _, _, _} = private_key
 106     public_key = {:RSAPublicKey, modulus, exponent}
 107     {:ok, private_key, public_key}
 108   end
 109
 110   def encode(private_key, doc) do
 111     type = "application/atom+xml"
 112     encoding = "base64url"
 113     alg = "RSA-SHA256"
 114
 115     signed_text = [doc, type, encoding, alg]
 116     |> Enum.map(&Base.url_encode64/1)
 117     |> Enum.join(".")
 118
 119     signature = signed_text
 120     |> :public_key.sign(:sha256, private_key)
 121     |> to_string
 122     |> Base.url_encode64
 123
 124     doc_base64 = doc
 125     |> Base.url_encode64
 126
 127     # Don't need proper xml building, these strings are safe to leave unescaped
 128     salmon = """
 129     <?xml version="1.0" encoding="UTF-8"?>
 130     <me:env xmlns:me="http://salmon-protocol.org/ns/magic-env">
 131       <me:data type="application/atom+xml">#{doc_base64}</me:data>
 132       <me:encoding>#{encoding}</me:encoding>
 133       <me:alg>#{alg}</me:alg>
 134       <me:sig>#{signature}</me:sig>
 135     </me:env>
 136     """
 137
 138     {:ok, salmon}
 139   end
 140
 141   def remote_users(%{data: %{"to" => to}}) do
 142     to
 143     |> Enum.map(fn(id) -> User.get_cached_by_ap_id(id) end)
 144     |> Enum.filter(fn(user) -> user && !user.local end)
 145   end
 146
 147   defp send_to_user(%{info: %{"salmon" => salmon}}, feed, poster) do
 148     with {:ok, %{status_code: code}} <- poster.(salmon, feed, [{"Content-Type", "application/magic-envelope+xml"}], timeout: 10000, recv_timeout: 20000) do
 149       Logger.debug(fn -> "Pushed to #{salmon}, code #{code}" end)
 150     else
 151       e -> Logger.debug(fn -> "Pushing salmon to #{salmon} failed, #{inspect(e)}" end)
 152     end
 153   end
 154
 155   defp send_to_user(_,_,_), do: nil
 156
 157   def publish(user, activity, poster \\ &@httpoison.post/4)
 158   def publish(%{info: %{"keys" => keys}} = user, activity, poster) do
 159     feed = ActivityRepresenter.to_simple_form(activity, user, true)
 160     |> ActivityRepresenter.wrap_with_entry
 161     |> :xmerl.export_simple(:xmerl_xml)
 162     |> to_string
 163
 164     if feed do
 165       {:ok, private, _} = keys_from_pem(keys)
 166       {:ok, feed} = encode(private, feed)
 167
 168       remote_users(activity)
 169       |> Enum.each(fn(remote_user) ->
 170         Task.start(fn ->
 171           Logger.debug(fn -> "sending salmon to #{remote_user.ap_id}" end)
 172           send_to_user(remote_user, feed, poster)
 173         end)
 174       end)
 175     end
 176   end
 177
 178   def publish(%{id: id}, _, _), do: Logger.debug(fn -> "Keys missing for user #{id}" end)
 179 end