ActivityPub: Handle incoming likes.

[akkoma] / lib / pleroma / web / http_signatures / http_signatures.ex

diff --git a/lib/pleroma/web/http_signatures/http_signatures.ex b/lib/pleroma/web/http_signatures/http_signatures.ex
index e2210285e6a74e6fcbab1890973f9511c794bb84..cdc5e1f3f505c78637d1967da6c86613cbc3e2cc 100644 (file)
--- a/lib/pleroma/web/http_signatures/http_signatures.ex
+++ b/lib/pleroma/web/http_signatures/http_signatures.ex
@@ -1,9 +1,12 @@
 # https://tools.ietf.org/html/draft-cavage-http-signatures-08
 defmodule Pleroma.Web.HTTPSignatures do
+  alias Pleroma.User
+  alias Pleroma.Web.ActivityPub.ActivityPub
+
   def split_signature(sig) do
-    default = %{"headers" => ["date"]}
+    default = %{"headers" => "date"}
 
-    sig
+    sig = sig
     |> String.trim()
     |> String.split(",")
     |> Enum.reduce(default, fn(part, acc) ->
@@ -11,12 +14,40 @@ defmodule Pleroma.Web.HTTPSignatures do
       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"])
     {:ok, sig} = Base.decode64(signature["signature"])
-    verify = :public_key.verify(sigstring, :sha256, sig, public_key)
+    :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} <- User.get_public_key_for_ap_id(actor_id) do
+      if validate_conn(conn, public_key) do
+        true
+      else
+        # Fetch user anew and try one more time
+        with actor_id <- conn.params["actor"],
+             {:ok, _user} <- ActivityPub.make_user_from_ap_id(actor_id),
+             {:ok, public_key} <- User.get_public_key_for_ap_id(actor_id) do
+          validate_conn(conn, public_key)
+        end
+      end
+    else
+      _ -> false
+    end
+  end
+
+  def validate_conn(conn, public_key) do
+    headers = Enum.into(conn.req_headers, %{})
+    signature = split_signature(headers["signature"])
+    validate(headers, signature, public_key)
   end
 
   def build_signing_string(headers, used_headers) do
@@ -24,4 +55,22 @@ defmodule Pleroma.Web.HTTPSignatures do
     |> Enum.map(fn (header) -> "#{header}: #{headers[header]}" end)
     |> Enum.join("\n")
   end
+
+  def sign(user, headers) do
+    with {:ok, %{info: %{"keys" => keys}}} <- Pleroma.Web.WebFinger.ensure_keys_present(user),
+         {:ok, private_key, _} = Pleroma.Web.Salmon.keys_from_pem(keys) do
+      sigstring = build_signing_string(headers, Map.keys(headers))
+      signature = :public_key.sign(sigstring, :sha256, private_key)
+      |> Base.encode64()
+
+      [
+        keyId: user.ap_id <> "#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