94 lines
3.2 KiB
Elixir
94 lines
3.2 KiB
Elixir
# https://tools.ietf.org/html/draft-cavage-http-signatures-08
|
|
defmodule Eventos.Service.HTTPSignatures do
|
|
alias Eventos.Actors.Actor
|
|
alias Eventos.Service.ActivityPub
|
|
require Logger
|
|
|
|
def split_signature(sig) do
|
|
default = %{"headers" => "date"}
|
|
|
|
sig =
|
|
sig
|
|
|> String.trim()
|
|
|> String.split(",")
|
|
|> Enum.reduce(default, fn part, acc ->
|
|
[key | rest] = String.split(part, "=")
|
|
value = Enum.join(rest, "=")
|
|
Map.put(acc, key, String.trim(value, "\""))
|
|
end)
|
|
|
|
Map.put(sig, "headers", String.split(sig["headers"], ~r/\s/))
|
|
end
|
|
|
|
def validate(headers, signature, public_key) do
|
|
sigstring = build_signing_string(headers, signature["headers"])
|
|
Logger.debug("Signature: #{signature["signature"]}")
|
|
Logger.debug("Sigstring: #{sigstring}")
|
|
{:ok, sig} = Base.decode64(signature["signature"])
|
|
:public_key.verify(sigstring, :sha256, sig, public_key)
|
|
end
|
|
|
|
def validate_conn(conn) do
|
|
# TODO: How to get the right key and see if it is actually valid for that request.
|
|
# For now, fetch the key for the actor.
|
|
with actor_id <- conn.params["actor"],
|
|
{:ok, public_key_code} <- Actor.get_public_key_for_url(actor_id),
|
|
[public_key] = :public_key.pem_decode(public_key_code),
|
|
public_key = :public_key.pem_entry_decode(public_key) do
|
|
if validate_conn(conn, public_key) do
|
|
true
|
|
else
|
|
Logger.info("Could not validate request, re-fetching user and trying one more time")
|
|
# Fetch user anew and try one more time
|
|
with actor_id <- conn.params["actor"],
|
|
{:ok, _actor} <- ActivityPub.make_actor_from_url(actor_id),
|
|
{:ok, public_key_code} <- Actor.get_public_key_for_url(actor_id),
|
|
[public_key] = :public_key.pem_decode(public_key_code),
|
|
public_key = :public_key.pem_entry_decode(public_key) do
|
|
validate_conn(conn, public_key)
|
|
end
|
|
end
|
|
else
|
|
e ->
|
|
Logger.debug("Could not found url for actor!")
|
|
Logger.debug(inspect e)
|
|
false
|
|
end
|
|
end
|
|
|
|
def validate_conn(conn, public_key) do
|
|
headers = Enum.into(conn.req_headers, %{})
|
|
[host_without_port, _] = String.split(headers["host"], ":")
|
|
headers = Map.put(headers, "host", host_without_port)
|
|
signature = split_signature(headers["signature"])
|
|
validate(headers, signature, public_key)
|
|
end
|
|
|
|
def build_signing_string(headers, used_headers) do
|
|
used_headers
|
|
|> Enum.map(fn header -> "#{header}: #{headers[header]}" end)
|
|
|> Enum.join("\n")
|
|
end
|
|
|
|
def sign(actor, headers) do
|
|
with {:ok, private_key_code} = Actor.get_private_key_for_actor(actor),
|
|
[private_key] = :public_key.pem_decode(private_key_code),
|
|
private_key = :public_key.pem_entry_decode(private_key) do
|
|
sigstring = build_signing_string(headers, Map.keys(headers))
|
|
|
|
signature =
|
|
:public_key.sign(sigstring, :sha256, private_key)
|
|
|> Base.encode64()
|
|
|
|
[
|
|
keyId: actor.url <> "#main-key",
|
|
algorithm: "rsa-sha256",
|
|
headers: Map.keys(headers) |> Enum.join(" "),
|
|
signature: signature
|
|
]
|
|
|> Enum.map(fn {k, v} -> "#{k}=\"#{v}\"" end)
|
|
|> Enum.join(",")
|
|
end
|
|
end
|
|
end
|