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   1 # Pleroma: A lightweight social networking server
   2 # Copyright © 2017-2018 Pleroma Authors <https://pleroma.social/>
   3 # SPDX-License-Identifier: AGPL-3.0-only
   4
   5 defmodule Pleroma.Web.ActivityPub.ActivityPub do
   6   alias Pleroma.{Activity, Repo, Object, Upload, User, Notification}
   7   alias Pleroma.Web.ActivityPub.{Transmogrifier, MRF}
   8   alias Pleroma.Web.WebFinger
   9   alias Pleroma.Web.Federator
  10   alias Pleroma.Web.OStatus
  11   import Ecto.Query
  12   import Pleroma.Web.ActivityPub.Utils
  13   require Logger
  14
  15   @httpoison Application.get_env(:pleroma, :httpoison)
  16
  17   # For Announce activities, we filter the recipients based on following status for any actors
  18   # that match actual users.  See issue #164 for more information about why this is necessary.
  19   defp get_recipients(%{"type" => "Announce"} = data) do
  20     to = data["to"] || []
  21     cc = data["cc"] || []
  22     recipients = to ++ cc
  23     actor = User.get_cached_by_ap_id(data["actor"])
  24
  25     recipients
  26     |> Enum.filter(fn recipient ->
  27       case User.get_cached_by_ap_id(recipient) do
  28         nil ->
  29           true
  30
  31         user ->
  32           User.following?(user, actor)
  33       end
  34     end)
  35
  36     {recipients, to, cc}
  37   end
  38
  39   defp get_recipients(data) do
  40     to = data["to"] || []
  41     cc = data["cc"] || []
  42     recipients = to ++ cc
  43     {recipients, to, cc}
  44   end
  45
  46   defp check_actor_is_active(actor) do
  47     if not is_nil(actor) do
  48       with user <- User.get_cached_by_ap_id(actor),
  49            false <- user.info.deactivated do
  50         :ok
  51       else
  52         _e -> :reject
  53       end
  54     else
  55       :ok
  56     end
  57   end
  58
  59   defp check_remote_limit(%{"object" => %{"content" => content}}) do
  60     limit = Pleroma.Config.get([:instance, :remote_limit])
  61     String.length(content) <= limit
  62   end
  63
  64   defp check_remote_limit(_), do: true
  65
  66   def insert(map, local \\ true) when is_map(map) do
  67     with nil <- Activity.normalize(map),
  68          map <- lazy_put_activity_defaults(map),
  69          :ok <- check_actor_is_active(map["actor"]),
  70          {_, true} <- {:remote_limit_error, check_remote_limit(map)},
  71          {:ok, map} <- MRF.filter(map),
  72          :ok <- insert_full_object(map) do
  73       {recipients, _, _} = get_recipients(map)
  74
  75       {:ok, activity} =
  76         Repo.insert(%Activity{
  77           data: map,
  78           local: local,
  79           actor: map["actor"],
  80           recipients: recipients
  81         })
  82
  83       Notification.create_notifications(activity)
  84       stream_out(activity)
  85       {:ok, activity}
  86     else
  87       %Activity{} = activity -> {:ok, activity}
  88       error -> {:error, error}
  89     end
  90   end
  91
  92   def stream_out(activity) do
  93     public = "https://www.w3.org/ns/activitystreams#Public"
  94
  95     if activity.data["type"] in ["Create", "Announce"] do
  96       Pleroma.Web.Streamer.stream("user", activity)
  97       Pleroma.Web.Streamer.stream("list", activity)
  98
  99       if Enum.member?(activity.data["to"], public) do
 100         Pleroma.Web.Streamer.stream("public", activity)
 101
 102         if activity.local do
 103           Pleroma.Web.Streamer.stream("public:local", activity)
 104         end
 105
 106         activity.data["object"]
 107         |> Map.get("tag", [])
 108         |> Enum.filter(fn tag -> is_bitstring(tag) end)
 109         |> Enum.map(fn tag -> Pleroma.Web.Streamer.stream("hashtag:" <> tag, activity) end)
 110
 111         if activity.data["object"]["attachment"] != [] do
 112           Pleroma.Web.Streamer.stream("public:media", activity)
 113
 114           if activity.local do
 115             Pleroma.Web.Streamer.stream("public:local:media", activity)
 116           end
 117         end
 118       else
 119         if !Enum.member?(activity.data["cc"] || [], public) &&
 120              !Enum.member?(
 121                activity.data["to"],
 122                User.get_by_ap_id(activity.data["actor"]).follower_address
 123              ),
 124            do: Pleroma.Web.Streamer.stream("direct", activity)
 125       end
 126     end
 127   end
 128
 129   def create(%{to: to, actor: actor, context: context, object: object} = params) do
 130     additional = params[:additional] || %{}
 131     # only accept false as false value
 132     local = !(params[:local] == false)
 133     published = params[:published]
 134
 135     with create_data <-
 136            make_create_data(
 137              %{to: to, actor: actor, published: published, context: context, object: object},
 138              additional
 139            ),
 140          {:ok, activity} <- insert(create_data, local),
 141          :ok <- maybe_federate(activity),
 142          {:ok, _actor} <- User.increase_note_count(actor) do
 143       {:ok, activity}
 144     end
 145   end
 146
 147   def accept(%{to: to, actor: actor, object: object} = params) do
 148     # only accept false as false value
 149     local = !(params[:local] == false)
 150
 151     with data <- %{"to" => to, "type" => "Accept", "actor" => actor, "object" => object},
 152          {:ok, activity} <- insert(data, local),
 153          :ok <- maybe_federate(activity) do
 154       {:ok, activity}
 155     end
 156   end
 157
 158   def reject(%{to: to, actor: actor, object: object} = params) do
 159     # only accept false as false value
 160     local = !(params[:local] == false)
 161
 162     with data <- %{"to" => to, "type" => "Reject", "actor" => actor, "object" => object},
 163          {:ok, activity} <- insert(data, local),
 164          :ok <- maybe_federate(activity) do
 165       {:ok, activity}
 166     end
 167   end
 168
 169   def update(%{to: to, cc: cc, actor: actor, object: object} = params) do
 170     # only accept false as false value
 171     local = !(params[:local] == false)
 172
 173     with data <- %{
 174            "to" => to,
 175            "cc" => cc,
 176            "type" => "Update",
 177            "actor" => actor,
 178            "object" => object
 179          },
 180          {:ok, activity} <- insert(data, local),
 181          :ok <- maybe_federate(activity) do
 182       {:ok, activity}
 183     end
 184   end
 185
 186   # TODO: This is weird, maybe we shouldn't check here if we can make the activity.
 187   def like(
 188         %User{ap_id: ap_id} = user,
 189         %Object{data: %{"id" => _}} = object,
 190         activity_id \\ nil,
 191         local \\ true
 192       ) do
 193     with nil <- get_existing_like(ap_id, object),
 194          like_data <- make_like_data(user, object, activity_id),
 195          {:ok, activity} <- insert(like_data, local),
 196          {:ok, object} <- add_like_to_object(activity, object),
 197          :ok <- maybe_federate(activity) do
 198       {:ok, activity, object}
 199     else
 200       %Activity{} = activity -> {:ok, activity, object}
 201       error -> {:error, error}
 202     end
 203   end
 204
 205   def unlike(
 206         %User{} = actor,
 207         %Object{} = object,
 208         activity_id \\ nil,
 209         local \\ true
 210       ) do
 211     with %Activity{} = like_activity <- get_existing_like(actor.ap_id, object),
 212          unlike_data <- make_unlike_data(actor, like_activity, activity_id),
 213          {:ok, unlike_activity} <- insert(unlike_data, local),
 214          {:ok, _activity} <- Repo.delete(like_activity),
 215          {:ok, object} <- remove_like_from_object(like_activity, object),
 216          :ok <- maybe_federate(unlike_activity) do
 217       {:ok, unlike_activity, like_activity, object}
 218     else
 219       _e -> {:ok, object}
 220     end
 221   end
 222
 223   def announce(
 224         %User{ap_id: _} = user,
 225         %Object{data: %{"id" => _}} = object,
 226         activity_id \\ nil,
 227         local \\ true
 228       ) do
 229     with true <- is_public?(object),
 230          announce_data <- make_announce_data(user, object, activity_id),
 231          {:ok, activity} <- insert(announce_data, local),
 232          {:ok, object} <- add_announce_to_object(activity, object),
 233          :ok <- maybe_federate(activity) do
 234       {:ok, activity, object}
 235     else
 236       error -> {:error, error}
 237     end
 238   end
 239
 240   def unannounce(
 241         %User{} = actor,
 242         %Object{} = object,
 243         activity_id \\ nil,
 244         local \\ true
 245       ) do
 246     with %Activity{} = announce_activity <- get_existing_announce(actor.ap_id, object),
 247          unannounce_data <- make_unannounce_data(actor, announce_activity, activity_id),
 248          {:ok, unannounce_activity} <- insert(unannounce_data, local),
 249          :ok <- maybe_federate(unannounce_activity),
 250          {:ok, _activity} <- Repo.delete(announce_activity),
 251          {:ok, object} <- remove_announce_from_object(announce_activity, object) do
 252       {:ok, unannounce_activity, object}
 253     else
 254       _e -> {:ok, object}
 255     end
 256   end
 257
 258   def follow(follower, followed, activity_id \\ nil, local \\ true) do
 259     with data <- make_follow_data(follower, followed, activity_id),
 260          {:ok, activity} <- insert(data, local),
 261          :ok <- maybe_federate(activity) do
 262       {:ok, activity}
 263     end
 264   end
 265
 266   def unfollow(follower, followed, activity_id \\ nil, local \\ true) do
 267     with %Activity{} = follow_activity <- fetch_latest_follow(follower, followed),
 268          {:ok, follow_activity} <- update_follow_state(follow_activity, "cancelled"),
 269          unfollow_data <- make_unfollow_data(follower, followed, follow_activity, activity_id),
 270          {:ok, activity} <- insert(unfollow_data, local),
 271          :ok <- maybe_federate(activity) do
 272       {:ok, activity}
 273     end
 274   end
 275
 276   def delete(%Object{data: %{"id" => id, "actor" => actor}} = object, local \\ true) do
 277     user = User.get_cached_by_ap_id(actor)
 278
 279     data = %{
 280       "type" => "Delete",
 281       "actor" => actor,
 282       "object" => id,
 283       "to" => [user.follower_address, "https://www.w3.org/ns/activitystreams#Public"]
 284     }
 285
 286     with {:ok, _} <- Object.delete(object),
 287          {:ok, activity} <- insert(data, local),
 288          :ok <- maybe_federate(activity),
 289          {:ok, _actor} <- User.decrease_note_count(user) do
 290       {:ok, activity}
 291     end
 292   end
 293
 294   def block(blocker, blocked, activity_id \\ nil, local \\ true) do
 295     ap_config = Application.get_env(:pleroma, :activitypub)
 296     unfollow_blocked = Keyword.get(ap_config, :unfollow_blocked)
 297     outgoing_blocks = Keyword.get(ap_config, :outgoing_blocks)
 298
 299     with true <- unfollow_blocked do
 300       follow_activity = fetch_latest_follow(blocker, blocked)
 301
 302       if follow_activity do
 303         unfollow(blocker, blocked, nil, local)
 304       end
 305     end
 306
 307     with true <- outgoing_blocks,
 308          block_data <- make_block_data(blocker, blocked, activity_id),
 309          {:ok, activity} <- insert(block_data, local),
 310          :ok <- maybe_federate(activity) do
 311       {:ok, activity}
 312     else
 313       _e -> {:ok, nil}
 314     end
 315   end
 316
 317   def unblock(blocker, blocked, activity_id \\ nil, local \\ true) do
 318     with %Activity{} = block_activity <- fetch_latest_block(blocker, blocked),
 319          unblock_data <- make_unblock_data(blocker, blocked, block_activity, activity_id),
 320          {:ok, activity} <- insert(unblock_data, local),
 321          :ok <- maybe_federate(activity) do
 322       {:ok, activity}
 323     end
 324   end
 325
 326   def fetch_activities_for_context(context, opts \\ %{}) do
 327     public = ["https://www.w3.org/ns/activitystreams#Public"]
 328
 329     recipients =
 330       if opts["user"], do: [opts["user"].ap_id | opts["user"].following] ++ public, else: public
 331
 332     query = from(activity in Activity)
 333
 334     query =
 335       query
 336       |> restrict_blocked(opts)
 337       |> restrict_recipients(recipients, opts["user"])
 338
 339     query =
 340       from(
 341         activity in query,
 342         where:
 343           fragment(
 344             "?->>'type' = ? and ?->>'context' = ?",
 345             activity.data,
 346             "Create",
 347             activity.data,
 348             ^context
 349           ),
 350         order_by: [desc: :id]
 351       )
 352
 353     Repo.all(query)
 354   end
 355
 356   def fetch_public_activities(opts \\ %{}) do
 357     q = fetch_activities_query(["https://www.w3.org/ns/activitystreams#Public"], opts)
 358
 359     q
 360     |> restrict_unlisted()
 361     |> Repo.all()
 362     |> Enum.reverse()
 363   end
 364
 365   @valid_visibilities ~w[direct unlisted public private]
 366
 367   defp restrict_visibility(query, %{visibility: "direct"}) do
 368     public = "https://www.w3.org/ns/activitystreams#Public"
 369
 370     from(
 371       activity in query,
 372       join: sender in User,
 373       on: sender.ap_id == activity.actor,
 374       # Are non-direct statuses with no to/cc possible?
 375       where:
 376         fragment(
 377           "not (? && ?)",
 378           [^public, sender.follower_address],
 379           activity.recipients
 380         )
 381     )
 382   end
 383
 384   defp restrict_visibility(_query, %{visibility: visibility})
 385        when visibility not in @valid_visibilities do
 386     Logger.error("Could not restrict visibility to #{visibility}")
 387   end
 388
 389   defp restrict_visibility(query, _visibility), do: query
 390
 391   def fetch_user_activities(user, reading_user, params \\ %{}) do
 392     params =
 393       params
 394       |> Map.put("type", ["Create", "Announce"])
 395       |> Map.put("actor_id", user.ap_id)
 396       |> Map.put("whole_db", true)
 397
 398     recipients =
 399       if reading_user do
 400         ["https://www.w3.org/ns/activitystreams#Public"] ++
 401           [reading_user.ap_id | reading_user.following]
 402       else
 403         ["https://www.w3.org/ns/activitystreams#Public"]
 404       end
 405
 406     fetch_activities(recipients, params)
 407     |> Enum.reverse()
 408   end
 409
 410   defp restrict_since(query, %{"since_id" => since_id}) do
 411     from(activity in query, where: activity.id > ^since_id)
 412   end
 413
 414   defp restrict_since(query, _), do: query
 415
 416   defp restrict_tag(query, %{"tag" => tag}) do
 417     from(
 418       activity in query,
 419       where: fragment("? <@ (? #> '{\"object\",\"tag\"}')", ^tag, activity.data)
 420     )
 421   end
 422
 423   defp restrict_tag(query, _), do: query
 424
 425   defp restrict_to_cc(query, recipients_to, recipients_cc) do
 426     from(
 427       activity in query,
 428       where:
 429         fragment(
 430           "(?->'to' \\?| ?) or (?->'cc' \\?| ?)",
 431           activity.data,
 432           ^recipients_to,
 433           activity.data,
 434           ^recipients_cc
 435         )
 436     )
 437   end
 438
 439   defp restrict_recipients(query, [], _user), do: query
 440
 441   defp restrict_recipients(query, recipients, nil) do
 442     from(activity in query, where: fragment("? && ?", ^recipients, activity.recipients))
 443   end
 444
 445   defp restrict_recipients(query, recipients, user) do
 446     from(
 447       activity in query,
 448       where: fragment("? && ?", ^recipients, activity.recipients),
 449       or_where: activity.actor == ^user.ap_id
 450     )
 451   end
 452
 453   defp restrict_limit(query, %{"limit" => limit}) do
 454     from(activity in query, limit: ^limit)
 455   end
 456
 457   defp restrict_limit(query, _), do: query
 458
 459   defp restrict_local(query, %{"local_only" => true}) do
 460     from(activity in query, where: activity.local == true)
 461   end
 462
 463   defp restrict_local(query, _), do: query
 464
 465   defp restrict_max(query, %{"max_id" => max_id}) do
 466     from(activity in query, where: activity.id < ^max_id)
 467   end
 468
 469   defp restrict_max(query, _), do: query
 470
 471   defp restrict_actor(query, %{"actor_id" => actor_id}) do
 472     from(activity in query, where: activity.actor == ^actor_id)
 473   end
 474
 475   defp restrict_actor(query, _), do: query
 476
 477   defp restrict_type(query, %{"type" => type}) when is_binary(type) do
 478     restrict_type(query, %{"type" => [type]})
 479   end
 480
 481   defp restrict_type(query, %{"type" => type}) do
 482     from(activity in query, where: fragment("?->>'type' = ANY(?)", activity.data, ^type))
 483   end
 484
 485   defp restrict_type(query, _), do: query
 486
 487   defp restrict_favorited_by(query, %{"favorited_by" => ap_id}) do
 488     from(
 489       activity in query,
 490       where: fragment("? <@ (? #> '{\"object\",\"likes\"}')", ^ap_id, activity.data)
 491     )
 492   end
 493
 494   defp restrict_favorited_by(query, _), do: query
 495
 496   defp restrict_media(query, %{"only_media" => val}) when val == "true" or val == "1" do
 497     from(
 498       activity in query,
 499       where: fragment("not (? #> '{\"object\",\"attachment\"}' = ?)", activity.data, ^[])
 500     )
 501   end
 502
 503   defp restrict_media(query, _), do: query
 504
 505   defp restrict_replies(query, %{"exclude_replies" => val}) when val == "true" or val == "1" do
 506     from(
 507       activity in query,
 508       where: fragment("?->'object'->>'inReplyTo' is null", activity.data)
 509     )
 510   end
 511
 512   defp restrict_replies(query, _), do: query
 513
 514   # Only search through last 100_000 activities by default
 515   defp restrict_recent(query, %{"whole_db" => true}), do: query
 516
 517   defp restrict_recent(query, _) do
 518     since = (Repo.aggregate(Activity, :max, :id) || 0) - 100_000
 519
 520     from(activity in query, where: activity.id > ^since)
 521   end
 522
 523   defp restrict_blocked(query, %{"blocking_user" => %User{info: info}}) do
 524     blocks = info.blocks || []
 525     domain_blocks = info.domain_blocks || []
 526
 527     from(
 528       activity in query,
 529       where: fragment("not (? = ANY(?))", activity.actor, ^blocks),
 530       where: fragment("not (?->'to' \\?| ?)", activity.data, ^blocks),
 531       where: fragment("not (split_part(?, '/', 3) = ANY(?))", activity.actor, ^domain_blocks)
 532     )
 533   end
 534
 535   defp restrict_blocked(query, _), do: query
 536
 537   defp restrict_unlisted(query) do
 538     from(
 539       activity in query,
 540       where:
 541         fragment(
 542           "not (coalesce(?->'cc', '{}'::jsonb) \\?| ?)",
 543           activity.data,
 544           ^["https://www.w3.org/ns/activitystreams#Public"]
 545         )
 546     )
 547   end
 548
 549   def fetch_activities_query(recipients, opts \\ %{}) do
 550     base_query =
 551       from(
 552         activity in Activity,
 553         limit: 20,
 554         order_by: [fragment("? desc nulls last", activity.id)]
 555       )
 556
 557     base_query
 558     |> restrict_recipients(recipients, opts["user"])
 559     |> restrict_tag(opts)
 560     |> restrict_since(opts)
 561     |> restrict_local(opts)
 562     |> restrict_limit(opts)
 563     |> restrict_max(opts)
 564     |> restrict_actor(opts)
 565     |> restrict_type(opts)
 566     |> restrict_favorited_by(opts)
 567     |> restrict_recent(opts)
 568     |> restrict_blocked(opts)
 569     |> restrict_media(opts)
 570     |> restrict_visibility(opts)
 571     |> restrict_replies(opts)
 572   end
 573
 574   def fetch_activities(recipients, opts \\ %{}) do
 575     fetch_activities_query(recipients, opts)
 576     |> Repo.all()
 577     |> Enum.reverse()
 578   end
 579
 580   def fetch_activities_bounded(recipients_to, recipients_cc, opts \\ %{}) do
 581     fetch_activities_query([], opts)
 582     |> restrict_to_cc(recipients_to, recipients_cc)
 583     |> Repo.all()
 584     |> Enum.reverse()
 585   end
 586
 587   def upload(file, opts \\ []) do
 588     with {:ok, data} <- Upload.store(file, opts) do
 589       obj_data =
 590         if opts[:actor] do
 591           Map.put(data, "actor", opts[:actor])
 592         else
 593           data
 594         end
 595
 596       Repo.insert(%Object{data: obj_data})
 597     end
 598   end
 599
 600   def user_data_from_user_object(data) do
 601     avatar =
 602       data["icon"]["url"] &&
 603         %{
 604           "type" => "Image",
 605           "url" => [%{"href" => data["icon"]["url"]}]
 606         }
 607
 608     banner =
 609       data["image"]["url"] &&
 610         %{
 611           "type" => "Image",
 612           "url" => [%{"href" => data["image"]["url"]}]
 613         }
 614
 615     locked = data["manuallyApprovesFollowers"] || false
 616     data = Transmogrifier.maybe_fix_user_object(data)
 617
 618     user_data = %{
 619       ap_id: data["id"],
 620       info: %{
 621         "ap_enabled" => true,
 622         "source_data" => data,
 623         "banner" => banner,
 624         "locked" => locked
 625       },
 626       avatar: avatar,
 627       name: data["name"],
 628       follower_address: data["followers"],
 629       bio: data["summary"]
 630     }
 631
 632     # nickname can be nil because of virtual actors
 633     user_data =
 634       if data["preferredUsername"] do
 635         Map.put(
 636           user_data,
 637           :nickname,
 638           "#{data["preferredUsername"]}@#{URI.parse(data["id"]).host}"
 639         )
 640       else
 641         Map.put(user_data, :nickname, nil)
 642       end
 643
 644     {:ok, user_data}
 645   end
 646
 647   def fetch_and_prepare_user_from_ap_id(ap_id) do
 648     with {:ok, data} <- fetch_and_contain_remote_object_from_id(ap_id) do
 649       user_data_from_user_object(data)
 650     else
 651       e -> Logger.error("Could not decode user at fetch #{ap_id}, #{inspect(e)}")
 652     end
 653   end
 654
 655   def make_user_from_ap_id(ap_id) do
 656     if _user = User.get_by_ap_id(ap_id) do
 657       Transmogrifier.upgrade_user_from_ap_id(ap_id)
 658     else
 659       with {:ok, data} <- fetch_and_prepare_user_from_ap_id(ap_id) do
 660         User.insert_or_update_user(data)
 661       else
 662         e -> {:error, e}
 663       end
 664     end
 665   end
 666
 667   def make_user_from_nickname(nickname) do
 668     with {:ok, %{"ap_id" => ap_id}} when not is_nil(ap_id) <- WebFinger.finger(nickname) do
 669       make_user_from_ap_id(ap_id)
 670     else
 671       _e -> {:error, "No AP id in WebFinger"}
 672     end
 673   end
 674
 675   def should_federate?(inbox, public) do
 676     if public do
 677       true
 678     else
 679       inbox_info = URI.parse(inbox)
 680       !Enum.member?(Pleroma.Config.get([:instance, :quarantined_instances], []), inbox_info.host)
 681     end
 682   end
 683
 684   def publish(actor, activity) do
 685     followers =
 686       if actor.follower_address in activity.recipients do
 687         {:ok, followers} = User.get_followers(actor)
 688         followers |> Enum.filter(&(!&1.local))
 689       else
 690         []
 691       end
 692
 693     public = is_public?(activity)
 694
 695     remote_inboxes =
 696       (Pleroma.Web.Salmon.remote_users(activity) ++ followers)
 697       |> Enum.filter(fn user -> User.ap_enabled?(user) end)
 698       |> Enum.map(fn %{info: %{source_data: data}} ->
 699         (is_map(data["endpoints"]) && Map.get(data["endpoints"], "sharedInbox")) || data["inbox"]
 700       end)
 701       |> Enum.uniq()
 702       |> Enum.filter(fn inbox -> should_federate?(inbox, public) end)
 703
 704     {:ok, data} = Transmogrifier.prepare_outgoing(activity.data)
 705     json = Jason.encode!(data)
 706
 707     Enum.each(remote_inboxes, fn inbox ->
 708       Federator.enqueue(:publish_single_ap, %{
 709         inbox: inbox,
 710         json: json,
 711         actor: actor,
 712         id: activity.data["id"]
 713       })
 714     end)
 715   end
 716
 717   def publish_one(%{inbox: inbox, json: json, actor: actor, id: id}) do
 718     Logger.info("Federating #{id} to #{inbox}")
 719     host = URI.parse(inbox).host
 720
 721     digest = "SHA-256=" <> (:crypto.hash(:sha256, json) |> Base.encode64())
 722
 723     signature =
 724       Pleroma.Web.HTTPSignatures.sign(actor, %{
 725         host: host,
 726         "content-length": byte_size(json),
 727         digest: digest
 728       })
 729
 730     @httpoison.post(
 731       inbox,
 732       json,
 733       [
 734         {"Content-Type", "application/activity+json"},
 735         {"signature", signature},
 736         {"digest", digest}
 737       ],
 738       hackney: [pool: :default]
 739     )
 740   end
 741
 742   # TODO:
 743   # This will create a Create activity, which we need internally at the moment.
 744   def fetch_object_from_id(id) do
 745     if object = Object.get_cached_by_ap_id(id) do
 746       {:ok, object}
 747     else
 748       Logger.info("Fetching #{id} via AP")
 749
 750       with {:ok, data} <- fetch_and_contain_remote_object_from_id(id),
 751            nil <- Object.normalize(data),
 752            params <- %{
 753              "type" => "Create",
 754              "to" => data["to"],
 755              "cc" => data["cc"],
 756              "actor" => data["actor"] || data["attributedTo"],
 757              "object" => data
 758            },
 759            :ok <- Transmogrifier.contain_origin(id, params),
 760            {:ok, activity} <- Transmogrifier.handle_incoming(params) do
 761         {:ok, Object.normalize(activity.data["object"])}
 762       else
 763         {:error, {:reject, nil}} ->
 764           {:reject, nil}
 765
 766         object = %Object{} ->
 767           {:ok, object}
 768
 769         _e ->
 770           Logger.info("Couldn't get object via AP, trying out OStatus fetching...")
 771
 772           case OStatus.fetch_activity_from_url(id) do
 773             {:ok, [activity | _]} -> {:ok, Object.normalize(activity.data["object"])}
 774             e -> e
 775           end
 776       end
 777     end
 778   end
 779
 780   def fetch_and_contain_remote_object_from_id(id) do
 781     Logger.info("Fetching #{id} via AP")
 782
 783     with true <- String.starts_with?(id, "http"),
 784          {:ok, %{body: body, status: code}} when code in 200..299 <-
 785            @httpoison.get(
 786              id,
 787              [{:Accept, "application/activity+json"}]
 788            ),
 789          {:ok, data} <- Jason.decode(body),
 790          :ok <- Transmogrifier.contain_origin_from_id(id, data) do
 791       {:ok, data}
 792     else
 793       e ->
 794         {:error, e}
 795     end
 796   end
 797
 798   def is_public?(activity) do
 799     "https://www.w3.org/ns/activitystreams#Public" in (activity.data["to"] ++
 800                                                          (activity.data["cc"] || []))
 801   end
 802
 803   def visible_for_user?(activity, nil) do
 804     is_public?(activity)
 805   end
 806
 807   def visible_for_user?(activity, user) do
 808     x = [user.ap_id | user.following]
 809     y = activity.data["to"] ++ (activity.data["cc"] || [])
 810     visible_for_user?(activity, nil) || Enum.any?(x, &(&1 in y))
 811   end
 812
 813   # guard
 814   def entire_thread_visible_for_user?(nil, _user), do: false
 815
 816   # child
 817   def entire_thread_visible_for_user?(
 818         %Activity{data: %{"object" => %{"inReplyTo" => parent_id}}} = tail,
 819         user
 820       )
 821       when is_binary(parent_id) do
 822     parent = Activity.get_in_reply_to_activity(tail)
 823     visible_for_user?(tail, user) && entire_thread_visible_for_user?(parent, user)
 824   end
 825
 826   # root
 827   def entire_thread_visible_for_user?(tail, user), do: visible_for_user?(tail, user)
 828
 829   # filter out broken threads
 830   def contain_broken_threads(%Activity{} = activity, %User{} = user) do
 831     entire_thread_visible_for_user?(activity, user)
 832   end
 833
 834   # do post-processing on a specific activity
 835   def contain_activity(%Activity{} = activity, %User{} = user) do
 836     contain_broken_threads(activity, user)
 837   end
 838
 839   # do post-processing on a timeline
 840   def contain_timeline(timeline, user) do
 841     timeline
 842     |> Enum.filter(fn activity ->
 843       contain_activity(activity, user)
 844     end)
 845   end
 846 end