forked from AkkomaGang/akkoma
129 lines
3.9 KiB
Elixir
129 lines
3.9 KiB
Elixir
defmodule Pleroma.Web.Salmon do
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use Bitwise
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alias Pleroma.Web.XML
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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)
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{:xmlObj, :string, sig} = :xmerl_xpath.string('string(//me:sig[1])', doc)
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{:xmlObj, :string, alg} = :xmerl_xpath.string('string(//me:alg[1])', doc)
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{:xmlObj, :string, encoding} = :xmerl_xpath.string('string(//me:encoding[1])', doc)
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{:xmlObj, :string, type} = :xmerl_xpath.string('string(//me:data[1]/@type)', doc)
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{:ok, data} = Base.url_decode64(to_string(data), ignore: :whitespace)
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{:ok, sig} = Base.url_decode64(to_string(sig), ignore: :whitespace)
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alg = to_string(alg)
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encoding = to_string(encoding)
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type = to_string(type)
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[data, type, encoding, alg, sig]
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end
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def fetch_magic_key(salmon) do
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[data, _, _, _, _] = decode(salmon)
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doc = XML.parse_document(data)
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{:xmlObj, :string, uri} = :xmerl_xpath.string('string(//author[1]/uri)', doc)
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uri = to_string(uri)
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base = URI.parse(uri).host
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# TODO: Find out if this endpoint is mandated by the standard.
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# At least diaspora does it differently
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{:ok, response} = HTTPoison.get(base <> "/.well-known/webfinger", ["Accept": "application/xrd+xml"], [params: [resource: uri]])
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doc = XML.parse_document(response.body)
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{:xmlObj, :string, magickey} = :xmerl_xpath.string('string(//Link[@rel="magic-public-key"]/@href)', doc)
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"data:application/magic-public-key," <> magickey = to_string(magickey)
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magickey
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end
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def decode_and_validate(magickey, salmon) do
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[data, type, encoding, alg, sig] = decode(salmon)
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signed_text = [data, type, encoding, alg]
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|> Enum.map(&Base.url_encode64/1)
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|> Enum.join(".")
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key = decode_key(magickey)
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verify = :public_key.verify(signed_text, :sha256, sig, key)
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if verify do
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{:ok, data}
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else
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:error
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end
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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
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|> String.split(".")
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|> Enum.map(&Base.url_decode64!/1)
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|> Enum.map(make_integer)
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{:RSAPublicKey, modulus, exponent}
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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
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exponent_enc = :binary.encode_unsigned(exponent) |> Base.url_encode64
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"RSA.#{modulus_enc}.#{exponent_enc}"
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end
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def generate_rsa_pem do
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port = Port.open({:spawn, "openssl genrsa"}, [:binary])
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{:ok, pem} = receive do
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{^port, {:data, pem}} -> {:ok, pem}
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end
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Port.close(port)
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if Regex.match?(~r/RSA PRIVATE KEY/, pem) do
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{:ok, pem}
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else
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:error
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end
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end
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def keys_from_pem(pem) do
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[private_key_code] = :public_key.pem_decode(pem)
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private_key = :public_key.pem_entry_decode(private_key_code)
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{:RSAPrivateKey, _, modulus, exponent, _, _, _, _, _, _, _} = private_key
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public_key = {:RSAPublicKey, modulus, exponent}
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{:ok, private_key, public_key}
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end
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def encode(private_key, doc) do
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type = "application/atom+xml"
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encoding = "base64url"
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alg = "RSA-SHA256"
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signed_text = [doc, type, encoding, alg]
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|> Enum.map(&Base.url_encode64/1)
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|> Enum.join(".")
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signature = :public_key.sign(signed_text, :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
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salmon = """
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<?xml version="1.0" encoding="UTF-8"?>
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<me:env xmlns:me="http://salmon-protocol.org/ns/magic-env">
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<me:data type="application/atom+xml">#{doc_base64}</me:data>
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<me:encoding>#{encoding}</me:encoding>
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<me:alg>#{alg}</me:alg>
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<me:sig>#{signature}</me:sig>
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</me:env>
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"""
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{:ok, salmon}
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end
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end
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