spc-pleroma/lib/pleroma/web/salmon/salmon.ex

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defmodule Pleroma.Web.Salmon do
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@httpoison Application.get_env(:pleroma, :httpoison)
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use Bitwise
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alias Pleroma.Web.XML
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alias Pleroma.Web.OStatus.ActivityRepresenter
alias Pleroma.User
require Logger
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def decode(salmon) do
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doc = XML.parse_document(salmon)
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{: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)
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[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
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end
def decode_and_validate(magickey, salmon) do
[data, type, encoding, alg, sig] = decode(salmon)
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signed_text =
[data, type, encoding, alg]
|> Enum.map(&Base.url_encode64/1)
|> Enum.join(".")
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key = decode_key(magickey)
verify = :public_key.verify(signed_text, :sha256, sig, key)
if verify do
{:ok, data}
else
:error
end
end
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def decode_key("RSA." <> magickey) do
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make_integer = fn bin ->
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list = :erlang.binary_to_list(bin)
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Enum.reduce(list, 0, fn el, acc -> acc <<< 8 ||| el end)
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end
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[modulus, exponent] =
magickey
|> String.split(".")
|> Enum.map(fn n -> Base.url_decode64!(n, padding: false) end)
|> Enum.map(make_integer)
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{:RSAPublicKey, modulus, exponent}
end
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def encode_key({:RSAPublicKey, modulus, exponent}) do
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modulus_enc = :binary.encode_unsigned(modulus) |> Base.url_encode64()
exponent_enc = :binary.encode_unsigned(exponent) |> Base.url_encode64()
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"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})
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def generate_rsa_pem do
key = :public_key.generate_key({:rsa, 2048, 65537})
entry = :public_key.pem_entry_encode(:RSAPrivateKey, key)
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pem = :public_key.pem_encode([entry]) |> String.trim_trailing()
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{:ok, pem}
end
rescue
_ ->
def generate_rsa_pem do
port = Port.open({:spawn, "openssl genrsa"}, [:binary])
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{:ok, pem} =
receive do
{^port, {:data, pem}} -> {:ok, pem}
end
Port.close(port)
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if Regex.match?(~r/RSA PRIVATE KEY/, pem) do
{:ok, pem}
else
:error
end
end
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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"
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signed_text =
[doc, type, encoding, alg]
|> Enum.map(&Base.url_encode64/1)
|> Enum.join(".")
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signature =
signed_text
|> :public_key.sign(:sha256, private_key)
|> to_string
|> Base.url_encode64()
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doc_base64 =
doc
|> Base.url_encode64()
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# 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
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def remote_users(%{data: %{"to" => to} = data}) do
to = to ++ (data["cc"] || [])
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to
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|> Enum.map(fn id -> User.get_cached_by_ap_id(id) end)
|> Enum.filter(fn user -> user && !user.local end)
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end
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defp send_to_user(%{info: %{salmon: salmon}}, feed, poster) do
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with {:ok, %{status: code}} <-
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poster.(
salmon,
feed,
[{"Content-Type", "application/magic-envelope+xml"}]
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) do
Logger.debug(fn -> "Pushed to #{salmon}, code #{code}" end)
else
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e -> Logger.debug(fn -> "Pushing Salmon to #{salmon} failed, #{inspect(e)}" end)
end
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end
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defp send_to_user(_, _, _), do: nil
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@supported_activities [
"Create",
"Follow",
"Like",
"Announce",
"Undo",
"Delete"
]
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def publish(user, activity, poster \\ &@httpoison.post/4)
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def publish(%{info: %{keys: keys}} = user, %{data: %{"type" => type}} = activity, poster)
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when type in @supported_activities do
feed = ActivityRepresenter.to_simple_form(activity, user, true)
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if feed do
feed =
ActivityRepresenter.wrap_with_entry(feed)
|> :xmerl.export_simple(:xmerl_xml)
|> to_string
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{:ok, private, _} = keys_from_pem(keys)
{:ok, feed} = encode(private, feed)
remote_users(activity)
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|> Enum.each(fn remote_user ->
Task.start(fn ->
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Logger.debug(fn -> "Sending Salmon to #{remote_user.ap_id}" end)
send_to_user(remote_user, feed, poster)
end)
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end)
end
end
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def publish(%{id: id}, _, _), do: Logger.debug(fn -> "Keys missing for user #{id}" end)
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end