Merge branch 'develop' into issue/2099

21 files changed, 1342 insertions, 65 deletions

diff --git a/lib/pleroma/web/activity_pub/activity_pub.ex b/lib/pleroma/web/activity_pub/activity_pub.ex
index 92fc1e422..06e8e1a7c 100644
--- a/lib/pleroma/web/activity_pub/activity_pub.ex
+++ b/lib/pleroma/web/activity_pub/activity_pub.ex
@@ -1270,10 +1270,12 @@ defmodule Pleroma.Web.ActivityPub.ActivityPub do
 
   def fetch_follow_information_for_user(user) do
     with {:ok, following_data} <-
-           Fetcher.fetch_and_contain_remote_object_from_id(user.following_address),
+           Fetcher.fetch_and_contain_remote_object_from_id(user.following_address,
+             force_http: true
+           ),
          {:ok, hide_follows} <- collection_private(following_data),
          {:ok, followers_data} <-
-           Fetcher.fetch_and_contain_remote_object_from_id(user.follower_address),
+           Fetcher.fetch_and_contain_remote_object_from_id(user.follower_address, force_http: true),
          {:ok, hide_followers} <- collection_private(followers_data) do
       {:ok,
        %{
@@ -1347,8 +1349,8 @@ defmodule Pleroma.Web.ActivityPub.ActivityPub do
     end
   end
 
-  def fetch_and_prepare_user_from_ap_id(ap_id) do
-    with {:ok, data} <- Fetcher.fetch_and_contain_remote_object_from_id(ap_id),
+  def fetch_and_prepare_user_from_ap_id(ap_id, opts \\ []) do
+    with {:ok, data} <- Fetcher.fetch_and_contain_remote_object_from_id(ap_id, opts),
          {:ok, data} <- user_data_from_user_object(data) do
       {:ok, maybe_update_follow_information(data)}
     else
@@ -1390,13 +1392,13 @@ defmodule Pleroma.Web.ActivityPub.ActivityPub do
     end
   end
 
-  def make_user_from_ap_id(ap_id) do
+  def make_user_from_ap_id(ap_id, opts \\ []) do
     user = User.get_cached_by_ap_id(ap_id)
 
     if user && !User.ap_enabled?(user) do
       Transmogrifier.upgrade_user_from_ap_id(ap_id)
     else
-      with {:ok, data} <- fetch_and_prepare_user_from_ap_id(ap_id) do
+      with {:ok, data} <- fetch_and_prepare_user_from_ap_id(ap_id, opts) do
         if user do
           user
           |> User.remote_user_changeset(data)
diff --git a/lib/pleroma/web/activity_pub/mrf/media_proxy_warming_policy.ex b/lib/pleroma/web/activity_pub/mrf/media_proxy_warming_policy.ex
index 98d595469..0fb05d3c4 100644
--- a/lib/pleroma/web/activity_pub/mrf/media_proxy_warming_policy.ex
+++ b/lib/pleroma/web/activity_pub/mrf/media_proxy_warming_policy.ex
@@ -12,17 +12,21 @@ defmodule Pleroma.Web.ActivityPub.MRF.MediaProxyWarmingPolicy do
 
   require Logger
 
-  @options [
+  @adapter_options [
     pool: :media,
     recv_timeout: 10_000
   ]
 
   def perform(:prefetch, url) do
-    Logger.debug("Prefetching #{inspect(url)}")
+    # Fetching only proxiable resources
+    if MediaProxy.enabled?() and MediaProxy.url_proxiable?(url) do
+      # If preview proxy is enabled, it'll also hit media proxy (so we're caching both requests)
+      prefetch_url = MediaProxy.preview_url(url)
 
-    url
-    |> MediaProxy.url()
-    |> HTTP.get([], @options)
+      Logger.debug("Prefetching #{inspect(url)} as #{inspect(prefetch_url)}")
+
+      HTTP.get(prefetch_url, [], @adapter_options)
+    end
   end
 
   def perform(:preload, %{"object" => %{"attachment" => attachments}} = _message) do
diff --git a/lib/pleroma/web/activity_pub/publisher.ex b/lib/pleroma/web/activity_pub/publisher.ex
index d88f7f3ee..9c3956683 100644
--- a/lib/pleroma/web/activity_pub/publisher.ex
+++ b/lib/pleroma/web/activity_pub/publisher.ex
@@ -13,6 +13,7 @@ defmodule Pleroma.Web.ActivityPub.Publisher do
   alias Pleroma.User
   alias Pleroma.Web.ActivityPub.Relay
   alias Pleroma.Web.ActivityPub.Transmogrifier
+  alias Pleroma.Web.FedSockets
 
   require Pleroma.Constants
 
@@ -50,15 +51,35 @@ defmodule Pleroma.Web.ActivityPub.Publisher do
   def publish_one(%{inbox: inbox, json: json, actor: %User{} = actor, id: id} = params) do
     Logger.debug("Federating #{id} to #{inbox}")
 
-    uri = URI.parse(inbox)
+    case FedSockets.get_or_create_fed_socket(inbox) do
+      {:ok, fedsocket} ->
+        Logger.debug("publishing via fedsockets - #{inspect(inbox)}")
+        FedSockets.publish(fedsocket, json)
 
+      _ ->
+        Logger.debug("publishing via http - #{inspect(inbox)}")
+        http_publish(inbox, actor, json, params)
+    end
+  end
+
+  def publish_one(%{actor_id: actor_id} = params) do
+    actor = User.get_cached_by_id(actor_id)
+
+    params
+    |> Map.delete(:actor_id)
+    |> Map.put(:actor, actor)
+    |> publish_one()
+  end
+
+  defp http_publish(inbox, actor, json, params) do
+    uri = %{path: path} = URI.parse(inbox)
     digest = "SHA-256=" <> (:crypto.hash(:sha256, json) |> Base.encode64())
 
     date = Pleroma.Signature.signed_date()
 
     signature =
       Pleroma.Signature.sign(actor, %{
-        "(request-target)": "post #{uri.path}",
+        "(request-target)": "post #{path}",
         host: signature_host(uri),
         "content-length": byte_size(json),
         digest: digest,
@@ -89,15 +110,6 @@ defmodule Pleroma.Web.ActivityPub.Publisher do
     end
   end
 
-  def publish_one(%{actor_id: actor_id} = params) do
-    actor = User.get_cached_by_id(actor_id)
-
-    params
-    |> Map.delete(:actor_id)
-    |> Map.put(:actor, actor)
-    |> publish_one()
-  end
-
   defp signature_host(%URI{port: port, scheme: scheme, host: host}) do
     if port == URI.default_port(scheme) do
       host
diff --git a/lib/pleroma/web/activity_pub/transmogrifier.ex b/lib/pleroma/web/activity_pub/transmogrifier.ex
index fcca014f0..aa6a69463 100644
--- a/lib/pleroma/web/activity_pub/transmogrifier.ex
+++ b/lib/pleroma/web/activity_pub/transmogrifier.ex
@@ -1000,7 +1000,7 @@ defmodule Pleroma.Web.ActivityPub.Transmogrifier do
 
   def upgrade_user_from_ap_id(ap_id) do
     with %User{local: false} = user <- User.get_cached_by_ap_id(ap_id),
-         {:ok, data} <- ActivityPub.fetch_and_prepare_user_from_ap_id(ap_id),
+         {:ok, data} <- ActivityPub.fetch_and_prepare_user_from_ap_id(ap_id, force_http: true),
          {:ok, user} <- update_user(user, data) do
       TransmogrifierWorker.enqueue("user_upgrade", %{"user_id" => user.id})
       {:ok, user}
diff --git a/lib/pleroma/web/fed_sockets/fed_registry.ex b/lib/pleroma/web/fed_sockets/fed_registry.ex
new file mode 100644
index 000000000..e00ea69c0
--- /dev/null
+++ b/lib/pleroma/web/fed_sockets/fed_registry.ex
@@ -0,0 +1,185 @@
+# Pleroma: A lightweight social networking server
+# Copyright © 2017-2020 Pleroma Authors <https://pleroma.social/>
+# SPDX-License-Identifier: AGPL-3.0-only
+
+defmodule Pleroma.Web.FedSockets.FedRegistry do
+  @moduledoc """
+  The FedRegistry stores the active FedSockets for quick retrieval.
+
+  The storage and retrieval portion of the FedRegistry is done in process through
+  elixir's `Registry` module for speed and its ability to monitor for terminated processes.
+
+  Dropped connections will be caught by `Registry` and deleted. Since the next
+  message will initiate a new connection there is no reason to try and reconnect at that point.
+
+  Normally outside modules should have no need to call or use the FedRegistry themselves.
+  """
+
+  alias Pleroma.Web.FedSockets.FedSocket
+  alias Pleroma.Web.FedSockets.SocketInfo
+
+  require Logger
+
+  @default_rejection_duration 15 * 60 * 1000
+  @rejections :fed_socket_rejections
+
+  @doc """
+  Retrieves a FedSocket from the Registry given it's origin.
+
+  The origin is expected to be a string identifying the endpoint "example.com" or "example2.com:8080"
+
+  Will return:
+    * {:ok, fed_socket} for working FedSockets
+    * {:error, :rejected} for origins that have been tried and refused within the rejection duration interval
+    * {:error, some_reason} usually :missing for unknown origins
+  """
+  def get_fed_socket(origin) do
+    case get_registry_data(origin) do
+      {:error, reason} ->
+        {:error, reason}
+
+      {:ok, %{state: :connected} = socket_info} ->
+        {:ok, socket_info}
+    end
+  end
+
+  @doc """
+  Adds a connected FedSocket to the Registry.
+
+  Always returns {:ok, fed_socket}
+  """
+  def add_fed_socket(origin, pid \\ nil) do
+    origin
+    |> SocketInfo.build(pid)
+    |> SocketInfo.connect()
+    |> add_socket_info
+  end
+
+  defp add_socket_info(%{origin: origin, state: :connected} = socket_info) do
+    case Registry.register(FedSockets.Registry, origin, socket_info) do
+      {:ok, _owner} ->
+        clear_prior_rejection(origin)
+        Logger.debug("fedsocket added: #{inspect(origin)}")
+
+        {:ok, socket_info}
+
+      {:error, {:already_registered, _pid}} ->
+        FedSocket.close(socket_info)
+        existing_socket_info = Registry.lookup(FedSockets.Registry, origin)
+
+        {:ok, existing_socket_info}
+
+      _ ->
+        {:error, :error_adding_socket}
+    end
+  end
+
+  @doc """
+  Mark this origin as having rejected a connection attempt.
+  This will keep it from getting additional connection attempts
+  for a period of time specified in the config.
+
+  Always returns {:ok, new_reg_data}
+  """
+  def set_host_rejected(uri) do
+    new_reg_data =
+      uri
+      |> SocketInfo.origin()
+      |> get_or_create_registry_data()
+      |> set_to_rejected()
+      |> save_registry_data()
+
+    {:ok, new_reg_data}
+  end
+
+  @doc """
+  Retrieves the FedRegistryData from the Registry given it's origin.
+
+  The origin is expected to be a string identifying the endpoint "example.com" or "example2.com:8080"
+
+  Will return:
+    * {:ok, fed_registry_data} for known origins
+    * {:error, :missing} for uniknown origins
+    * {:error, :cache_error} indicating some low level runtime issues
+  """
+  def get_registry_data(origin) do
+    case Registry.lookup(FedSockets.Registry, origin) do
+      [] ->
+        if is_rejected?(origin) do
+          Logger.debug("previously rejected fedsocket requested")
+          {:error, :rejected}
+        else
+          {:error, :missing}
+        end
+
+      [{_pid, %{state: :connected} = socket_info}] ->
+        {:ok, socket_info}
+
+      _ ->
+        {:error, :cache_error}
+    end
+  end
+
+  @doc """
+  Retrieves a map of all sockets from the Registry. The keys are the origins and the values are the corresponding SocketInfo
+  """
+  def list_all do
+    (list_all_connected() ++ list_all_rejected())
+    |> Enum.into(%{})
+  end
+
+  defp list_all_connected do
+    FedSockets.Registry
+    |> Registry.select([{{:"$1", :_, :"$3"}, [], [{{:"$1", :"$3"}}]}])
+  end
+
+  defp list_all_rejected do
+    {:ok, keys} = Cachex.keys(@rejections)
+
+    {:ok, registry_data} =
+      Cachex.execute(@rejections, fn worker ->
+        Enum.map(keys, fn k -> {k, Cachex.get!(worker, k)} end)
+      end)
+
+    registry_data
+  end
+
+  defp clear_prior_rejection(origin),
+    do: Cachex.del(@rejections, origin)
+
+  defp is_rejected?(origin) do
+    case Cachex.get(@rejections, origin) do
+      {:ok, nil} ->
+        false
+
+      {:ok, _} ->
+        true
+    end
+  end
+
+  defp get_or_create_registry_data(origin) do
+    case get_registry_data(origin) do
+      {:error, :missing} ->
+        %SocketInfo{origin: origin}
+
+      {:ok, socket_info} ->
+        socket_info
+    end
+  end
+
+  defp save_registry_data(%SocketInfo{origin: origin, state: :connected} = socket_info) do
+    {:ok, true} = Registry.update_value(FedSockets.Registry, origin, fn _ -> socket_info end)
+    socket_info
+  end
+
+  defp save_registry_data(%SocketInfo{origin: origin, state: :rejected} = socket_info) do
+    rejection_expiration =
+      Pleroma.Config.get([:fed_sockets, :rejection_duration], @default_rejection_duration)
+
+    {:ok, true} = Cachex.put(@rejections, origin, socket_info, ttl: rejection_expiration)
+    socket_info
+  end
+
+  defp set_to_rejected(%SocketInfo{} = socket_info),
+    do: %SocketInfo{socket_info | state: :rejected}
+end
diff --git a/lib/pleroma/web/fed_sockets/fed_socket.ex b/lib/pleroma/web/fed_sockets/fed_socket.ex
new file mode 100644
index 000000000..98d64e65a
--- /dev/null
+++ b/lib/pleroma/web/fed_sockets/fed_socket.ex
@@ -0,0 +1,137 @@
+# Pleroma: A lightweight social networking server
+# Copyright © 2017-2020 Pleroma Authors <https://pleroma.social/>
+# SPDX-License-Identifier: AGPL-3.0-only
+
+defmodule Pleroma.Web.FedSockets.FedSocket do
+  @moduledoc """
+  The FedSocket module abstracts the actions to be taken taken on connections regardless of
+  whether the connection started as inbound or outbound.
+
+
+  Normally outside modules will have no need to call the FedSocket module directly.
+  """
+
+  alias Pleroma.Object
+  alias Pleroma.Object.Containment
+  alias Pleroma.User
+  alias Pleroma.Web.ActivityPub.ObjectView
+  alias Pleroma.Web.ActivityPub.UserView
+  alias Pleroma.Web.ActivityPub.Visibility
+  alias Pleroma.Web.FedSockets.FetchRegistry
+  alias Pleroma.Web.FedSockets.IngesterWorker
+  alias Pleroma.Web.FedSockets.OutgoingHandler
+  alias Pleroma.Web.FedSockets.SocketInfo
+
+  require Logger
+
+  @shake "61dd18f7-f1e6-49a4-939a-a749fcdc1103"
+
+  def connect_to_host(uri) do
+    case OutgoingHandler.start_link(uri) do
+      {:ok, pid} ->
+        {:ok, pid}
+
+      error ->
+        {:error, error}
+    end
+  end
+
+  def close(%SocketInfo{pid: socket_pid}),
+    do: Process.send(socket_pid, :close, [])
+
+  def publish(%SocketInfo{pid: socket_pid}, json) do
+    %{action: :publish, data: json}
+    |> Jason.encode!()
+    |> send_packet(socket_pid)
+  end
+
+  def fetch(%SocketInfo{pid: socket_pid}, id) do
+    fetch_uuid = FetchRegistry.register_fetch(id)
+
+    %{action: :fetch, data: id, uuid: fetch_uuid}
+    |> Jason.encode!()
+    |> send_packet(socket_pid)
+
+    wait_for_fetch_to_return(fetch_uuid, 0)
+  end
+
+  def receive_package(%SocketInfo{} = fed_socket, json) do
+    json
+    |> Jason.decode!()
+    |> process_package(fed_socket)
+  end
+
+  defp wait_for_fetch_to_return(uuid, cntr) do
+    case FetchRegistry.check_fetch(uuid) do
+      {:error, :waiting} ->
+        Process.sleep(:math.pow(cntr, 3) |> Kernel.trunc())
+        wait_for_fetch_to_return(uuid, cntr + 1)
+
+      {:error, :missing} ->
+        Logger.error("FedSocket fetch timed out - #{inspect(uuid)}")
+        {:error, :timeout}
+
+      {:ok, _fr} ->
+        FetchRegistry.pop_fetch(uuid)
+    end
+  end
+
+  defp process_package(%{"action" => "publish", "data" => data}, %{origin: origin} = _fed_socket) do
+    if Containment.contain_origin(origin, data) do
+      IngesterWorker.enqueue("ingest", %{"object" => data})
+    end
+
+    {:reply, %{"action" => "publish_reply", "status" => "processed"}}
+  end
+
+  defp process_package(%{"action" => "fetch_reply", "uuid" => uuid, "data" => data}, _fed_socket) do
+    FetchRegistry.register_fetch_received(uuid, data)
+    {:noreply, nil}
+  end
+
+  defp process_package(%{"action" => "fetch", "uuid" => uuid, "data" => ap_id}, _fed_socket) do
+    {:ok, data} = render_fetched_data(ap_id, uuid)
+    {:reply, data}
+  end
+
+  defp process_package(%{"action" => "publish_reply"}, _fed_socket) do
+    {:noreply, nil}
+  end
+
+  defp process_package(other, _fed_socket) do
+    Logger.warn("unknown json packages received #{inspect(other)}")
+    {:noreply, nil}
+  end
+
+  defp render_fetched_data(ap_id, uuid) do
+    {:ok,
+     %{
+       "action" => "fetch_reply",
+       "status" => "processed",
+       "uuid" => uuid,
+       "data" => represent_item(ap_id)
+     }}
+  end
+
+  defp represent_item(ap_id) do
+    case User.get_by_ap_id(ap_id) do
+      nil ->
+        object = Object.get_cached_by_ap_id(ap_id)
+
+        if Visibility.is_public?(object) do
+          Phoenix.View.render_to_string(ObjectView, "object.json", object: object)
+        else
+          nil
+        end
+
+      user ->
+        Phoenix.View.render_to_string(UserView, "user.json", user: user)
+    end
+  end
+
+  defp send_packet(data, socket_pid) do
+    Process.send(socket_pid, {:send, data}, [])
+  end
+
+  def shake, do: @shake
+end
diff --git a/lib/pleroma/web/fed_sockets/fed_sockets.ex b/lib/pleroma/web/fed_sockets/fed_sockets.ex
new file mode 100644
index 000000000..1fd5899c8
--- /dev/null
+++ b/lib/pleroma/web/fed_sockets/fed_sockets.ex
@@ -0,0 +1,185 @@
+# Pleroma: A lightweight social networking server
+# Copyright © 2017-2020 Pleroma Authors <https://pleroma.social/>
+# SPDX-License-Identifier: AGPL-3.0-only
+
+defmodule Pleroma.Web.FedSockets do
+  @moduledoc """
+  This documents the FedSockets framework. A framework for federating
+  ActivityPub objects between servers via persistant WebSocket connections.
+
+  FedSockets allow servers to authenticate on first contact and maintain that
+  connection, eliminating the need to authenticate every time data needs to be shared.
+
+  ## Protocol
+  FedSockets currently support 2 types of data transfer:
+    * `publish` method which doesn't require a response
+    * `fetch` method requires a response be sent
+
+    ### Publish
+    The publish operation sends a json encoded map of the shape:
+      %{action: :publish, data: json}
+    and accepts (but does not require) a reply of form:
+      %{"action" => "publish_reply"}
+
+    The outgoing params represent
+      * data: ActivityPub object encoded into json
+
+
+    ### Fetch
+    The fetch operation sends a json encoded map of the shape:
+      %{action: :fetch, data: id, uuid: fetch_uuid}
+    and requires a reply of form:
+      %{"action" => "fetch_reply", "uuid" => uuid, "data" => data}
+
+    The outgoing params represent
+      * id: an ActivityPub object URI
+      * uuid: a unique uuid generated by the sender
+
+    The reply params represent
+      * data: an ActivityPub object encoded into json
+      * uuid: the uuid sent along with the fetch request
+
+  ## Examples
+  Clients of FedSocket transfers shouldn't need to use any of the functions outside of this module.
+
+  A typical publish operation can be performed through the following code, and a fetch operation in a similar manner.
+
+    case FedSockets.get_or_create_fed_socket(inbox) do
+      {:ok, fedsocket} ->
+        FedSockets.publish(fedsocket, json)
+
+      _ ->
+        alternative_publish(inbox, actor, json, params)
+    end
+
+  ## Configuration
+  FedSockets have the following config settings
+
+  config :pleroma, :fed_sockets,
+  enabled: true,
+  ping_interval: :timer.seconds(15),
+  connection_duration: :timer.hours(1),
+  rejection_duration: :timer.hours(1),
+  fed_socket_fetches: [
+    default: 12_000,
+    interval: 3_000,
+    lazy: false
+  ]
+    * enabled - turn FedSockets on or off with this flag. Can be toggled at runtime.
+    * connection_duration - How long a FedSocket can sit idle before it's culled.
+    * rejection_duration - After failing to make a FedSocket connection a host will be excluded
+    from further connections for this amount of time
+    * fed_socket_fetches - Use these parameters to pass options to the Cachex queue backing the FetchRegistry
+    * fed_socket_rejections - Use these parameters to pass options to the Cachex queue backing the FedRegistry
+
+    Cachex options are
+      * default: the minimum amount of time a fetch can wait before it times out.
+      * interval: the interval between checks for timed out entries. This plus the default represent the maximum time allowed
+      * lazy: leave at false for consistant and fast lookups, set to true for stricter timeout enforcement
+
+  """
+  require Logger
+
+  alias Pleroma.Web.FedSockets.FedRegistry
+  alias Pleroma.Web.FedSockets.FedSocket
+  alias Pleroma.Web.FedSockets.SocketInfo
+
+  @doc """
+  returns a FedSocket for the given origin. Will reuse an existing one or create a new one.
+
+  address is expected to be a fully formed URL such as:
+  "http://www.example.com" or "http://www.example.com:8080"
+
+  It can and usually does include additional path parameters,
+  but these are ignored as the FedSockets are organized by host and port info alone.
+  """
+  def get_or_create_fed_socket(address) do
+    with {:cache, {:error, :missing}} <- {:cache, get_fed_socket(address)},
+         {:connect, {:ok, _pid}} <- {:connect, FedSocket.connect_to_host(address)},
+         {:cache, {:ok, fed_socket}} <- {:cache, get_fed_socket(address)} do
+      Logger.debug("fedsocket created for - #{inspect(address)}")
+      {:ok, fed_socket}
+    else
+      {:cache, {:ok, socket}} ->
+        Logger.debug("fedsocket found in cache - #{inspect(address)}")
+        {:ok, socket}
+
+      {:cache, {:error, :rejected} = e} ->
+        e
+
+      {:connect, {:error, _host}} ->
+        Logger.debug("set host rejected for - #{inspect(address)}")
+        FedRegistry.set_host_rejected(address)
+        {:error, :rejected}
+
+      {_, {:error, :disabled}} ->
+        {:error, :disabled}
+
+      {_, {:error, reason}} ->
+        Logger.warn("get_or_create_fed_socket error - #{inspect(reason)}")
+        {:error, reason}
+    end
+  end
+
+  @doc """
+  returns a FedSocket for the given origin. Will not create a new FedSocket if one does not exist.
+
+  address is expected to be a fully formed URL such as:
+    "http://www.example.com" or "http://www.example.com:8080"
+  """
+  def get_fed_socket(address) do
+    origin = SocketInfo.origin(address)
+
+    with {:config, true} <- {:config, Pleroma.Config.get([:fed_sockets, :enabled], false)},
+         {:ok, socket} <- FedRegistry.get_fed_socket(origin) do
+      {:ok, socket}
+    else
+      {:config, _} ->
+        {:error, :disabled}
+
+      {:error, :rejected} ->
+        Logger.debug("FedSocket previously rejected - #{inspect(origin)}")
+        {:error, :rejected}
+
+      {:error, reason} ->
+        {:error, reason}
+    end
+  end
+
+  @doc """
+  Sends the supplied data via the publish protocol.
+  It will not block waiting for a reply.
+  Returns :ok but this is not an indication of a successful transfer.
+
+  the data is expected to be JSON encoded binary data.
+  """
+  def publish(%SocketInfo{} = fed_socket, json) do
+    FedSocket.publish(fed_socket, json)
+  end
+
+  @doc """
+  Sends the supplied data via the fetch protocol.
+  It will block waiting for a reply or timeout.
+
+  Returns {:ok, object} where object is the requested object (or nil)
+          {:error, :timeout} in the event the message was not responded to
+
+  the id is expected to be the URI of an ActivityPub object.
+  """
+  def fetch(%SocketInfo{} = fed_socket, id) do
+    FedSocket.fetch(fed_socket, id)
+  end
+
+  @doc """
+  Disconnect all and restart FedSockets.
+  This is mainly used in development and testing but could be useful in production.
+  """
+  def reset do
+    FedRegistry
+    |> Process.whereis()
+    |> Process.exit(:testing)
+  end
+
+  def uri_for_origin(origin),
+    do: "ws://#{origin}/api/fedsocket/v1"
+end
diff --git a/lib/pleroma/web/fed_sockets/fetch_registry.ex b/lib/pleroma/web/fed_sockets/fetch_registry.ex
new file mode 100644
index 000000000..7897f0fc6
--- /dev/null
+++ b/lib/pleroma/web/fed_sockets/fetch_registry.ex
@@ -0,0 +1,151 @@
+# Pleroma: A lightweight social networking server
+# Copyright © 2017-2020 Pleroma Authors <https://pleroma.social/>
+# SPDX-License-Identifier: AGPL-3.0-only
+
+defmodule Pleroma.Web.FedSockets.FetchRegistry do
+  @moduledoc """
+  The FetchRegistry acts as a broker for fetch requests and return values.
+  This allows calling processes to block while waiting for a reply.
+  It doesn't impose it's own process instead using `Cachex` to handle fetches in process, allowing
+  multi threaded processes to avoid bottlenecking.
+
+  Normally outside modules will have no need to call or use the FetchRegistry themselves.
+
+  The `Cachex` parameters can be controlled from the config. Since exact timeout intervals
+  aren't necessary the following settings are used by default:
+
+  config :pleroma, :fed_sockets,
+    fed_socket_fetches: [
+      default: 12_000,
+      interval: 3_000,
+      lazy: false
+    ]
+
+  """
+
+  defmodule FetchRegistryData do
+    defstruct uuid: nil,
+              sent_json: nil,
+              received_json: nil,
+              sent_at: nil,
+              received_at: nil
+  end
+
+  alias Ecto.UUID
+
+  require Logger
+
+  @fetches :fed_socket_fetches
+
+  @doc """
+  Registers a json request wth the FetchRegistry and returns the identifying UUID.
+  """
+  def register_fetch(json) do
+    %FetchRegistryData{uuid: uuid} =
+      json
+      |> new_registry_data
+      |> save_registry_data
+
+    uuid
+  end
+
+  @doc """
+  Reports on the status of a Fetch given the identifying UUID.
+
+  Will return
+    * {:ok, fetched_object} if a fetch has completed
+    * {:error, :waiting} if a fetch is still pending
+    * {:error, other_error} usually :missing to indicate a fetch that has timed out
+  """
+  def check_fetch(uuid) do
+    case get_registry_data(uuid) do
+      {:ok, %FetchRegistryData{received_at: nil}} ->
+        {:error, :waiting}
+
+      {:ok, %FetchRegistryData{} = reg_data} ->
+        {:ok, reg_data}
+
+      e ->
+        e
+    end
+  end
+
+  @doc """
+  Retrieves the response to a fetch given the identifying UUID.
+  The completed fetch will be deleted from the FetchRegistry
+
+  Will return
+    * {:ok, fetched_object} if a fetch has completed
+    * {:error, :waiting} if a fetch is still pending
+    * {:error, other_error} usually :missing to indicate a fetch that has timed out
+  """
+  def pop_fetch(uuid) do
+    case check_fetch(uuid) do
+      {:ok, %FetchRegistryData{received_json: received_json}} ->
+        delete_registry_data(uuid)
+        {:ok, received_json}
+
+      e ->
+        e
+    end
+  end
+
+  @doc """
+  This is called to register a fetch has returned.
+  It expects the result data along with the UUID that was sent in the request
+
+  Will return the fetched object or :error
+  """
+  def register_fetch_received(uuid, data) do
+    case get_registry_data(uuid) do
+      {:ok, %FetchRegistryData{received_at: nil} = reg_data} ->
+        reg_data
+        |> set_fetch_received(data)
+        |> save_registry_data()
+
+      {:ok, %FetchRegistryData{} = reg_data} ->
+        Logger.warn("tried to add fetched data twice - #{uuid}")
+        reg_data
+
+      {:error, _} ->
+        Logger.warn("Error adding fetch to registry - #{uuid}")
+        :error
+    end
+  end
+
+  defp new_registry_data(json) do
+    %FetchRegistryData{
+      uuid: UUID.generate(),
+      sent_json: json,
+      sent_at: :erlang.monotonic_time(:millisecond)
+    }
+  end
+
+  defp get_registry_data(origin) do
+    case Cachex.get(@fetches, origin) do
+      {:ok, nil} ->
+        {:error, :missing}
+
+      {:ok, reg_data} ->
+        {:ok, reg_data}
+
+      _ ->
+        {:error, :cache_error}
+    end
+  end
+
+  defp set_fetch_received(%FetchRegistryData{} = reg_data, data),
+    do: %FetchRegistryData{
+      reg_data
+      | received_at: :erlang.monotonic_time(:millisecond),
+        received_json: data
+    }
+
+  defp save_registry_data(%FetchRegistryData{uuid: uuid} = reg_data) do
+    {:ok, true} = Cachex.put(@fetches, uuid, reg_data)
+    reg_data
+  end
+
+  defp delete_registry_data(origin),
+    do: {:ok, true} = Cachex.del(@fetches, origin)
+end
diff --git a/lib/pleroma/web/fed_sockets/incoming_handler.ex b/lib/pleroma/web/fed_sockets/incoming_handler.ex
new file mode 100644
index 000000000..49d0d9d84
--- /dev/null
+++ b/lib/pleroma/web/fed_sockets/incoming_handler.ex
@@ -0,0 +1,88 @@
+# Pleroma: A lightweight social networking server
+# Copyright © 2017-2020 Pleroma Authors <https://pleroma.social/>
+# SPDX-License-Identifier: AGPL-3.0-only
+
+defmodule Pleroma.Web.FedSockets.IncomingHandler do
+  require Logger
+
+  alias Pleroma.Web.FedSockets.FedRegistry
+  alias Pleroma.Web.FedSockets.FedSocket
+  alias Pleroma.Web.FedSockets.SocketInfo
+
+  import HTTPSignatures, only: [validate_conn: 1, split_signature: 1]
+
+  @behaviour :cowboy_websocket
+
+  def init(req, state) do
+    shake = FedSocket.shake()
+
+    with true <- Pleroma.Config.get([:fed_sockets, :enabled]),
+         sec_protocol <- :cowboy_req.header("sec-websocket-protocol", req, nil),
+         headers = %{"(request-target)" => ^shake} <- :cowboy_req.headers(req),
+         true <- validate_conn(%{req_headers: headers}),
+         %{"keyId" => origin} <- split_signature(headers["signature"]) do
+      req =
+        if is_nil(sec_protocol) do
+          req
+        else
+          :cowboy_req.set_resp_header("sec-websocket-protocol", sec_protocol, req)
+        end
+
+      {:cowboy_websocket, req, %{origin: origin}, %{}}
+    else
+      _ ->
+        {:ok, req, state}
+    end
+  end
+
+  def websocket_init(%{origin: origin}) do
+    case FedRegistry.add_fed_socket(origin) do
+      {:ok, socket_info} ->
+        {:ok, socket_info}
+
+      e ->
+        Logger.error("FedSocket websocket_init failed - #{inspect(e)}")
+        {:error, inspect(e)}
+    end
+  end
+
+  # Use the ping to  check if the connection should be expired
+  def websocket_handle(:ping, socket_info) do
+    if SocketInfo.expired?(socket_info) do
+      {:stop, socket_info}
+    else
+      {:ok, socket_info, :hibernate}
+    end
+  end
+
+  def websocket_handle({:text, data}, socket_info) do
+    socket_info = SocketInfo.touch(socket_info)
+
+    case FedSocket.receive_package(socket_info, data) do
+      {:noreply, _} ->
+        {:ok, socket_info}
+
+      {:reply, reply} ->
+        {:reply, {:text, Jason.encode!(reply)}, socket_info}
+
+      {:error, reason} ->
+        Logger.error("incoming error - receive_package: #{inspect(reason)}")
+        {:ok, socket_info}
+    end
+  end
+
+  def websocket_info({:send, message}, socket_info) do
+    socket_info = SocketInfo.touch(socket_info)
+
+    {:reply, {:text, message}, socket_info}
+  end
+
+  def websocket_info(:close, state) do
+    {:stop, state}
+  end
+
+  def websocket_info(message, state) do
+    Logger.debug("#{__MODULE__} unknown message #{inspect(message)}")
+    {:ok, state}
+  end
+end
diff --git a/lib/pleroma/web/fed_sockets/ingester_worker.ex b/lib/pleroma/web/fed_sockets/ingester_worker.ex
new file mode 100644
index 000000000..325f2a4ab
--- /dev/null
+++ b/lib/pleroma/web/fed_sockets/ingester_worker.ex
@@ -0,0 +1,33 @@
+# Pleroma: A lightweight social networking server
+# Copyright © 2017-2020 Pleroma Authors <https://pleroma.social/>
+# SPDX-License-Identifier: AGPL-3.0-only
+
+defmodule Pleroma.Web.FedSockets.IngesterWorker do
+  use Pleroma.Workers.WorkerHelper, queue: "ingestion_queue"
+  require Logger
+
+  alias Pleroma.Web.Federator
+
+  @impl Oban.Worker
+  def perform(%Job{args: %{"op" => "ingest", "object" => ingestee}}) do
+    try do
+      ingestee
+      |> Jason.decode!()
+      |> do_ingestion()
+    rescue
+      e ->
+        Logger.error("IngesterWorker error - #{inspect(e)}")
+        e
+    end
+  end
+
+  defp do_ingestion(params) do
+    case Federator.incoming_ap_doc(params) do
+      {:error, reason} ->
+        {:error, reason}
+
+      {:ok, object} ->
+        {:ok, object}
+    end
+  end
+end
diff --git a/lib/pleroma/web/fed_sockets/outgoing_handler.ex b/lib/pleroma/web/fed_sockets/outgoing_handler.ex
new file mode 100644
index 000000000..6ddef17fe
--- /dev/null
+++ b/lib/pleroma/web/fed_sockets/outgoing_handler.ex
@@ -0,0 +1,146 @@
+# Pleroma: A lightweight social networking server
+# Copyright © 2017-2020 Pleroma Authors <https://pleroma.social/>
+# SPDX-License-Identifier: AGPL-3.0-only
+
+defmodule Pleroma.Web.FedSockets.OutgoingHandler do
+  use GenServer
+
+  require Logger
+
+  alias Pleroma.Web.ActivityPub.InternalFetchActor
+  alias Pleroma.Web.FedSockets
+  alias Pleroma.Web.FedSockets.FedRegistry
+  alias Pleroma.Web.FedSockets.FedSocket
+  alias Pleroma.Web.FedSockets.SocketInfo
+
+  def start_link(uri) do
+    GenServer.start_link(__MODULE__, %{uri: uri})
+  end
+
+  def init(%{uri: uri}) do
+    case initiate_connection(uri) do
+      {:ok, ws_origin, conn_pid} ->
+        FedRegistry.add_fed_socket(ws_origin, conn_pid)
+
+      {:error, reason} ->
+        Logger.debug("Outgoing connection failed - #{inspect(reason)}")
+        :ignore
+    end
+  end
+
+  def handle_info({:gun_ws, conn_pid, _ref, {:text, data}}, socket_info) do
+    socket_info = SocketInfo.touch(socket_info)
+
+    case FedSocket.receive_package(socket_info, data) do
+      {:noreply, _} ->
+        {:noreply, socket_info}
+
+      {:reply, reply} ->
+        :gun.ws_send(conn_pid, {:text, Jason.encode!(reply)})
+        {:noreply, socket_info}
+
+      {:error, reason} ->
+        Logger.error("incoming error - receive_package: #{inspect(reason)}")
+        {:noreply, socket_info}
+    end
+  end
+
+  def handle_info(:close, state) do
+    Logger.debug("Sending close frame !!!!!!!")
+    {:close, state}
+  end
+
+  def handle_info({:gun_down, _pid, _prot, :closed, _}, state) do
+    {:stop, :normal, state}
+  end
+
+  def handle_info({:send, data}, %{conn_pid: conn_pid} = socket_info) do
+    socket_info = SocketInfo.touch(socket_info)
+    :gun.ws_send(conn_pid, {:text, data})
+    {:noreply, socket_info}
+  end
+
+  def handle_info({:gun_ws, _, _, :pong}, state) do
+    {:noreply, state, :hibernate}
+  end
+
+  def handle_info(msg, state) do
+    Logger.debug("#{__MODULE__} unhandled event #{inspect(msg)}")
+    {:noreply, state}
+  end
+
+  def terminate(reason, state) do
+    Logger.debug(
+      "#{__MODULE__} terminating outgoing connection for #{inspect(state)} for #{inspect(reason)}"
+    )
+
+    {:ok, state}
+  end
+
+  def initiate_connection(uri) do
+    ws_uri =
+      uri
+      |> SocketInfo.origin()
+      |> FedSockets.uri_for_origin()
+
+    %{host: host, port: port, path: path} = URI.parse(ws_uri)
+
+    with {:ok, conn_pid} <- :gun.open(to_charlist(host), port),
+         {:ok, _} <- :gun.await_up(conn_pid),
+         reference <- :gun.get(conn_pid, to_charlist(path)),
+         {:response, :fin, 204, _} <- :gun.await(conn_pid, reference),
+         headers <- build_headers(uri),
+         ref <- :gun.ws_upgrade(conn_pid, to_charlist(path), headers, %{silence_pings: false}) do
+      receive do
+        {:gun_upgrade, ^conn_pid, ^ref, [<<"websocket">>], _} ->
+          {:ok, ws_uri, conn_pid}
+      after
+        15_000 ->
+          Logger.debug("Fedsocket timeout connecting to #{inspect(uri)}")
+          {:error, :timeout}
+      end
+    else
+      {:response, :nofin, 404, _} ->
+        {:error, :fedsockets_not_supported}
+
+      e ->
+        Logger.debug("Fedsocket error connecting to #{inspect(uri)}")
+        {:error, e}
+    end
+  end
+
+  defp build_headers(uri) do
+    host_for_sig = uri |> URI.parse() |> host_signature()
+
+    shake = FedSocket.shake()
+    digest = "SHA-256=" <> (:crypto.hash(:sha256, shake) |> Base.encode64())
+    date = Pleroma.Signature.signed_date()
+    shake_size = byte_size(shake)
+
+    signature_opts = %{
+      "(request-target)": shake,
+      "content-length": to_charlist("#{shake_size}"),
+      date: date,
+      digest: digest,
+      host: host_for_sig
+    }
+
+    signature = Pleroma.Signature.sign(InternalFetchActor.get_actor(), signature_opts)
+
+    [
+      {'signature', to_charlist(signature)},
+      {'date', date},
+      {'digest', to_charlist(digest)},
+      {'content-length', to_charlist("#{shake_size}")},
+      {to_charlist("(request-target)"), to_charlist(shake)}
+    ]
+  end
+
+  defp host_signature(%{host: host, scheme: scheme, port: port}) do
+    if port == URI.default_port(scheme) do
+      host
+    else
+      "#{host}:#{port}"
+    end
+  end
+end
diff --git a/lib/pleroma/web/fed_sockets/socket_info.ex b/lib/pleroma/web/fed_sockets/socket_info.ex
new file mode 100644
index 000000000..d6fdffe1a
--- /dev/null
+++ b/lib/pleroma/web/fed_sockets/socket_info.ex
@@ -0,0 +1,52 @@
+# Pleroma: A lightweight social networking server
+# Copyright © 2017-2020 Pleroma Authors <https://pleroma.social/>
+# SPDX-License-Identifier: AGPL-3.0-only
+
+defmodule Pleroma.Web.FedSockets.SocketInfo do
+  defstruct origin: nil,
+            pid: nil,
+            conn_pid: nil,
+            state: :default,
+            connected_until: nil
+
+  alias Pleroma.Web.FedSockets.SocketInfo
+  @default_connection_duration 15 * 60 * 1000
+
+  def build(uri, conn_pid \\ nil) do
+    uri
+    |> build_origin()
+    |> build_pids(conn_pid)
+    |> touch()
+  end
+
+  def touch(%SocketInfo{} = socket_info),
+    do: %{socket_info | connected_until: new_ttl()}
+
+  def connect(%SocketInfo{} = socket_info),
+    do: %{socket_info | state: :connected}
+
+  def expired?(%{connected_until: connected_until}),
+    do: connected_until < :erlang.monotonic_time(:millisecond)
+
+  def origin(uri),
+    do: build_origin(uri).origin
+
+  defp build_pids(socket_info, conn_pid),
+    do: struct(socket_info, pid: self(), conn_pid: conn_pid)
+
+  defp build_origin(uri) when is_binary(uri),
+    do: uri |> URI.parse() |> build_origin
+
+  defp build_origin(%{host: host, port: nil, scheme: scheme}),
+    do: build_origin(%{host: host, port: URI.default_port(scheme)})
+
+  defp build_origin(%{host: host, port: port}),
+    do: %SocketInfo{origin: "#{host}:#{port}"}
+
+  defp new_ttl do
+    connection_duration =
+      Pleroma.Config.get([:fed_sockets, :connection_duration], @default_connection_duration)
+
+    :erlang.monotonic_time(:millisecond) + connection_duration
+  end
+end
diff --git a/lib/pleroma/web/fed_sockets/supervisor.ex b/lib/pleroma/web/fed_sockets/supervisor.ex
new file mode 100644
index 000000000..a5f4bebfb
--- /dev/null
+++ b/lib/pleroma/web/fed_sockets/supervisor.ex
@@ -0,0 +1,59 @@
+# Pleroma: A lightweight social networking server
+# Copyright © 2017-2020 Pleroma Authors <https://pleroma.social/>
+# SPDX-License-Identifier: AGPL-3.0-only
+
+defmodule Pleroma.Web.FedSockets.Supervisor do
+  use Supervisor
+  import Cachex.Spec
+
+  def start_link(opts) do
+    Supervisor.start_link(__MODULE__, opts, name: __MODULE__)
+  end
+
+  def init(args) do
+    children = [
+      build_cache(:fed_socket_fetches, args),
+      build_cache(:fed_socket_rejections, args),
+      {Registry, keys: :unique, name: FedSockets.Registry, meta: [rejected: %{}]}
+    ]
+
+    opts = [strategy: :one_for_all, name: Pleroma.Web.Streamer.Supervisor]
+    Supervisor.init(children, opts)
+  end
+
+  defp build_cache(name, args) do
+    opts = get_opts(name, args)
+
+    %{
+      id: String.to_atom("#{name}_cache"),
+      start: {Cachex, :start_link, [name, opts]},
+      type: :worker
+    }
+  end
+
+  defp get_opts(cache_name, args)
+       when cache_name in [:fed_socket_fetches, :fed_socket_rejections] do
+    default = get_opts_or_config(args, cache_name, :default, 15_000)
+    interval = get_opts_or_config(args, cache_name, :interval, 3_000)
+    lazy = get_opts_or_config(args, cache_name, :lazy, false)
+
+    [expiration: expiration(default: default, interval: interval, lazy: lazy)]
+  end
+
+  defp get_opts(name, args) do
+    Keyword.get(args, name, [])
+  end
+
+  defp get_opts_or_config(args, name, key, default) do
+    args
+    |> Keyword.get(name, [])
+    |> Keyword.get(key)
+    |> case do
+      nil ->
+        Pleroma.Config.get([:fed_sockets, name, key], default)
+
+      value ->
+        value
+    end
+  end
+end
diff --git a/lib/pleroma/web/mastodon_api/views/account_view.ex b/lib/pleroma/web/mastodon_api/views/account_view.ex
index d2a30a548..121ba1693 100644
--- a/lib/pleroma/web/mastodon_api/views/account_view.ex
+++ b/lib/pleroma/web/mastodon_api/views/account_view.ex
@@ -181,8 +181,10 @@ defmodule Pleroma.Web.MastodonAPI.AccountView do
     user = User.sanitize_html(user, User.html_filter_policy(opts[:for]))
     display_name = user.name || user.nickname
 
-    image = User.avatar_url(user) |> MediaProxy.url()
+    avatar = User.avatar_url(user) |> MediaProxy.url()
+    avatar_static = User.avatar_url(user) |> MediaProxy.preview_url(static: true)
     header = User.banner_url(user) |> MediaProxy.url()
+    header_static = User.banner_url(user) |> MediaProxy.preview_url(static: true)
 
     following_count =
       if !user.hide_follows_count or !user.hide_follows or opts[:for] == user do
@@ -247,10 +249,10 @@ defmodule Pleroma.Web.MastodonAPI.AccountView do
       statuses_count: user.note_count,
       note: user.bio,
       url: user.uri || user.ap_id,
-      avatar: image,
-      avatar_static: image,
+      avatar: avatar,
+      avatar_static: avatar_static,
       header: header,
-      header_static: header,
+      header_static: header_static,
       emojis: emojis,
       fields: user.fields,
       bot: bot,
diff --git a/lib/pleroma/web/mastodon_api/views/status_view.ex b/lib/pleroma/web/mastodon_api/views/status_view.ex
index 94b8dc8c6..435bcde15 100644
--- a/lib/pleroma/web/mastodon_api/views/status_view.ex
+++ b/lib/pleroma/web/mastodon_api/views/status_view.ex
@@ -415,6 +415,7 @@ defmodule Pleroma.Web.MastodonAPI.StatusView do
     [attachment_url | _] = attachment["url"]
     media_type = attachment_url["mediaType"] || attachment_url["mimeType"] || "image"
     href = attachment_url["href"] |> MediaProxy.url()
+    href_preview = attachment_url["href"] |> MediaProxy.preview_url()
 
     type =
       cond do
@@ -430,7 +431,7 @@ defmodule Pleroma.Web.MastodonAPI.StatusView do
       id: to_string(attachment["id"] || hash_id),
       url: href,
       remote_url: href,
-      preview_url: href,
+      preview_url: href_preview,
       text_url: href,
       type: type,
       description: attachment["name"],
diff --git a/lib/pleroma/web/media_proxy/invalidation.ex b/lib/pleroma/web/media_proxy/invalidation.ex
index 5808861e6..4f4340478 100644
--- a/lib/pleroma/web/media_proxy/invalidation.ex
+++ b/lib/pleroma/web/media_proxy/invalidation.ex
@@ -33,6 +33,8 @@ defmodule Pleroma.Web.MediaProxy.Invalidation do
   def prepare_urls(urls) do
     urls
     |> List.wrap()
-    |> Enum.map(&MediaProxy.url/1)
+    |> Enum.map(fn url -> [MediaProxy.url(url), MediaProxy.preview_url(url)] end)
+    |> List.flatten()
+    |> Enum.uniq()
   end
 end
diff --git a/lib/pleroma/web/media_proxy/media_proxy.ex b/lib/pleroma/web/media_proxy/media_proxy.ex
index e18dd8224..8656b8cad 100644
--- a/lib/pleroma/web/media_proxy/media_proxy.ex
+++ b/lib/pleroma/web/media_proxy/media_proxy.ex
@@ -4,6 +4,7 @@
 
 defmodule Pleroma.Web.MediaProxy do
   alias Pleroma.Config
+  alias Pleroma.Helpers.UriHelper
   alias Pleroma.Upload
   alias Pleroma.Web
   alias Pleroma.Web.MediaProxy.Invalidation
@@ -40,27 +41,35 @@ defmodule Pleroma.Web.MediaProxy do
   def url("/" <> _ = url), do: url
 
   def url(url) do
-    if disabled?() or not url_proxiable?(url) do
-      url
-    else
+    if enabled?() and url_proxiable?(url) do
       encode_url(url)
+    else
+      url
     end
   end
 
   @spec url_proxiable?(String.t()) :: boolean()
   def url_proxiable?(url) do
-    if local?(url) or whitelisted?(url) do
-      false
+    not local?(url) and not whitelisted?(url)
+  end
+
+  def preview_url(url, preview_params \\ []) do
+    if preview_enabled?() do
+      encode_preview_url(url, preview_params)
     else
-      true
+      url(url)
     end
   end
 
-  defp disabled?, do: !Config.get([:media_proxy, :enabled], false)
+  def enabled?, do: Config.get([:media_proxy, :enabled], false)
+
+  # Note: media proxy must be enabled for media preview proxy in order to load all
+  #   non-local non-whitelisted URLs through it and be sure that body size constraint is preserved.
+  def preview_enabled?, do: enabled?() and !!Config.get([:media_preview_proxy, :enabled])
 
-  defp local?(url), do: String.starts_with?(url, Pleroma.Web.base_url())
+  def local?(url), do: String.starts_with?(url, Pleroma.Web.base_url())
 
-  defp whitelisted?(url) do
+  def whitelisted?(url) do
     %{host: domain} = URI.parse(url)
 
     mediaproxy_whitelist_domains =
@@ -85,17 +94,29 @@ defmodule Pleroma.Web.MediaProxy do
 
   defp maybe_get_domain_from_url(domain), do: domain
 
-  def encode_url(url) do
+  defp base64_sig64(url) do
     base64 = Base.url_encode64(url, @base64_opts)
 
     sig64 =
       base64
-      |> signed_url
+      |> signed_url()
       |> Base.url_encode64(@base64_opts)
 
+    {base64, sig64}
+  end
+
+  def encode_url(url) do
+    {base64, sig64} = base64_sig64(url)
+
     build_url(sig64, base64, filename(url))
   end
 
+  def encode_preview_url(url, preview_params \\ []) do
+    {base64, sig64} = base64_sig64(url)
+
+    build_preview_url(sig64, base64, filename(url), preview_params)
+  end
+
   def decode_url(sig, url) do
     with {:ok, sig} <- Base.url_decode64(sig, @base64_opts),
          signature when signature == sig <- signed_url(url) do
@@ -113,10 +134,14 @@ defmodule Pleroma.Web.MediaProxy do
     if path = URI.parse(url_or_path).path, do: Path.basename(path)
   end
 
-  def build_url(sig_base64, url_base64, filename \\ nil) do
+  def base_url do
+    Config.get([:media_proxy, :base_url], Web.base_url())
+  end
+
+  defp proxy_url(path, sig_base64, url_base64, filename) do
     [
-      Config.get([:media_proxy, :base_url], Web.base_url()),
-      "proxy",
+      base_url(),
+      path,
       sig_base64,
       url_base64,
       filename
@@ -124,4 +149,38 @@ defmodule Pleroma.Web.MediaProxy do
     |> Enum.filter(& &1)
     |> Path.join()
   end
+
+  def build_url(sig_base64, url_base64, filename \\ nil) do
+    proxy_url("proxy", sig_base64, url_base64, filename)
+  end
+
+  def build_preview_url(sig_base64, url_base64, filename \\ nil, preview_params \\ []) do
+    uri = proxy_url("proxy/preview", sig_base64, url_base64, filename)
+
+    UriHelper.modify_uri_params(uri, preview_params)
+  end
+
+  def verify_request_path_and_url(
+        %Plug.Conn{params: %{"filename" => _}, request_path: request_path},
+        url
+      ) do
+    verify_request_path_and_url(request_path, url)
+  end
+
+  def verify_request_path_and_url(request_path, url) when is_binary(request_path) do
+    filename = filename(url)
+
+    if filename && not basename_matches?(request_path, filename) do
+      {:wrong_filename, filename}
+    else
+      :ok
+    end
+  end
+
+  def verify_request_path_and_url(_, _), do: :ok
+
+  defp basename_matches?(path, filename) do
+    basename = Path.basename(path)
+    basename == filename or URI.decode(basename) == filename or URI.encode(basename) == filename
+  end
 end
diff --git a/lib/pleroma/web/media_proxy/media_proxy_controller.ex b/lib/pleroma/web/media_proxy/media_proxy_controller.ex
index 9a64b0ef3..90651ed9b 100644
--- a/lib/pleroma/web/media_proxy/media_proxy_controller.ex
+++ b/lib/pleroma/web/media_proxy/media_proxy_controller.ex
@@ -5,44 +5,201 @@
 defmodule Pleroma.Web.MediaProxy.MediaProxyController do
   use Pleroma.Web, :controller
 
+  alias Pleroma.Config
+  alias Pleroma.Helpers.MediaHelper
+  alias Pleroma.Helpers.UriHelper
   alias Pleroma.ReverseProxy
   alias Pleroma.Web.MediaProxy
+  alias Plug.Conn
 
-  @default_proxy_opts [max_body_length: 25 * 1_048_576, http: [follow_redirect: true]]
-
-  def remote(conn, %{"sig" => sig64, "url" => url64} = params) do
-    with config <- Pleroma.Config.get([:media_proxy], []),
-         true <- Keyword.get(config, :enabled, false),
+  def remote(conn, %{"sig" => sig64, "url" => url64}) do
+    with {_, true} <- {:enabled, MediaProxy.enabled?()},
          {:ok, url} <- MediaProxy.decode_url(sig64, url64),
          {_, false} <- {:in_banned_urls, MediaProxy.in_banned_urls(url)},
-         :ok <- filename_matches(params, conn.request_path, url) do
-      ReverseProxy.call(conn, url, Keyword.get(config, :proxy_opts, @default_proxy_opts))
+         :ok <- MediaProxy.verify_request_path_and_url(conn, url) do
+      ReverseProxy.call(conn, url, media_proxy_opts())
     else
-      error when error in [false, {:in_banned_urls, true}] ->
-        send_resp(conn, 404, Plug.Conn.Status.reason_phrase(404))
+      {:enabled, false} ->
+        send_resp(conn, 404, Conn.Status.reason_phrase(404))
+
+      {:in_banned_urls, true} ->
+        send_resp(conn, 404, Conn.Status.reason_phrase(404))
 
       {:error, :invalid_signature} ->
-        send_resp(conn, 403, Plug.Conn.Status.reason_phrase(403))
+        send_resp(conn, 403, Conn.Status.reason_phrase(403))
 
       {:wrong_filename, filename} ->
         redirect(conn, external: MediaProxy.build_url(sig64, url64, filename))
     end
   end
 
-  def filename_matches(%{"filename" => _} = _, path, url) do
-    filename = MediaProxy.filename(url)
+  def preview(%Conn{} = conn, %{"sig" => sig64, "url" => url64}) do
+    with {_, true} <- {:enabled, MediaProxy.preview_enabled?()},
+         {:ok, url} <- MediaProxy.decode_url(sig64, url64),
+         :ok <- MediaProxy.verify_request_path_and_url(conn, url) do
+      handle_preview(conn, url)
+    else
+      {:enabled, false} ->
+        send_resp(conn, 404, Conn.Status.reason_phrase(404))
+
+      {:error, :invalid_signature} ->
+        send_resp(conn, 403, Conn.Status.reason_phrase(403))
+
+      {:wrong_filename, filename} ->
+        redirect(conn, external: MediaProxy.build_preview_url(sig64, url64, filename))
+    end
+  end
+
+  defp handle_preview(conn, url) do
+    media_proxy_url = MediaProxy.url(url)
+
+    with {:ok, %{status: status} = head_response} when status in 200..299 <-
+           Pleroma.HTTP.request("head", media_proxy_url, [], [], pool: :media) do
+      content_type = Tesla.get_header(head_response, "content-type")
+      content_length = Tesla.get_header(head_response, "content-length")
+      content_length = content_length && String.to_integer(content_length)
+      static = conn.params["static"] in ["true", true]
+
+      cond do
+        static and content_type == "image/gif" ->
+          handle_jpeg_preview(conn, media_proxy_url)
+
+        static ->
+          drop_static_param_and_redirect(conn)
+
+        content_type == "image/gif" ->
+          redirect(conn, external: media_proxy_url)
+
+        min_content_length_for_preview() > 0 and content_length > 0 and
+            content_length < min_content_length_for_preview() ->
+          redirect(conn, external: media_proxy_url)
+
+        true ->
+          handle_preview(content_type, conn, media_proxy_url)
+      end
+    else
+      # If HEAD failed, redirecting to media proxy URI doesn't make much sense; returning an error
+      {_, %{status: status}} ->
+        send_resp(conn, :failed_dependency, "Can't fetch HTTP headers (HTTP #{status}).")
+
+      {:error, :recv_response_timeout} ->
+        send_resp(conn, :failed_dependency, "HEAD request timeout.")
+
+      _ ->
+        send_resp(conn, :failed_dependency, "Can't fetch HTTP headers.")
+    end
+  end
+
+  defp handle_preview("image/png" <> _ = _content_type, conn, media_proxy_url) do
+    handle_png_preview(conn, media_proxy_url)
+  end
+
+  defp handle_preview("image/" <> _ = _content_type, conn, media_proxy_url) do
+    handle_jpeg_preview(conn, media_proxy_url)
+  end
+
+  defp handle_preview("video/" <> _ = _content_type, conn, media_proxy_url) do
+    handle_video_preview(conn, media_proxy_url)
+  end
+
+  defp handle_preview(_unsupported_content_type, conn, media_proxy_url) do
+    fallback_on_preview_error(conn, media_proxy_url)
+  end
+
+  defp handle_png_preview(conn, media_proxy_url) do
+    quality = Config.get!([:media_preview_proxy, :image_quality])
+    {thumbnail_max_width, thumbnail_max_height} = thumbnail_max_dimensions()
+
+    with {:ok, thumbnail_binary} <-
+           MediaHelper.image_resize(
+             media_proxy_url,
+             %{
+               max_width: thumbnail_max_width,
+               max_height: thumbnail_max_height,
+               quality: quality,
+               format: "png"
+             }
+           ) do
+      conn
+      |> put_preview_response_headers(["image/png", "preview.png"])
+      |> send_resp(200, thumbnail_binary)
+    else
+      _ ->
+        fallback_on_preview_error(conn, media_proxy_url)
+    end
+  end
+
+  defp handle_jpeg_preview(conn, media_proxy_url) do
+    quality = Config.get!([:media_preview_proxy, :image_quality])
+    {thumbnail_max_width, thumbnail_max_height} = thumbnail_max_dimensions()
 
-    if filename && does_not_match(path, filename) do
-      {:wrong_filename, filename}
+    with {:ok, thumbnail_binary} <-
+           MediaHelper.image_resize(
+             media_proxy_url,
+             %{max_width: thumbnail_max_width, max_height: thumbnail_max_height, quality: quality}
+           ) do
+      conn
+      |> put_preview_response_headers()
+      |> send_resp(200, thumbnail_binary)
     else
-      :ok
+      _ ->
+        fallback_on_preview_error(conn, media_proxy_url)
     end
   end
 
-  def filename_matches(_, _, _), do: :ok
+  defp handle_video_preview(conn, media_proxy_url) do
+    with {:ok, thumbnail_binary} <-
+           MediaHelper.video_framegrab(media_proxy_url) do
+      conn
+      |> put_preview_response_headers()
+      |> send_resp(200, thumbnail_binary)
+    else
+      _ ->
+        fallback_on_preview_error(conn, media_proxy_url)
+    end
+  end
+
+  defp drop_static_param_and_redirect(conn) do
+    uri_without_static_param =
+      conn
+      |> current_url()
+      |> UriHelper.modify_uri_params(%{}, ["static"])
+
+    redirect(conn, external: uri_without_static_param)
+  end
+
+  defp fallback_on_preview_error(conn, media_proxy_url) do
+    redirect(conn, external: media_proxy_url)
+  end
+
+  defp put_preview_response_headers(
+         conn,
+         [content_type, filename] = _content_info \\ ["image/jpeg", "preview.jpg"]
+       ) do
+    conn
+    |> put_resp_header("content-type", content_type)
+    |> put_resp_header("content-disposition", "inline; filename=\"#{filename}\"")
+    |> put_resp_header("cache-control", ReverseProxy.default_cache_control_header())
+  end
+
+  defp thumbnail_max_dimensions do
+    config = media_preview_proxy_config()
+
+    thumbnail_max_width = Keyword.fetch!(config, :thumbnail_max_width)
+    thumbnail_max_height = Keyword.fetch!(config, :thumbnail_max_height)
+
+    {thumbnail_max_width, thumbnail_max_height}
+  end
+
+  defp min_content_length_for_preview do
+    Keyword.get(media_preview_proxy_config(), :min_content_length, 0)
+  end
+
+  defp media_preview_proxy_config do
+    Config.get!([:media_preview_proxy])
+  end
 
-  defp does_not_match(path, filename) do
-    basename = Path.basename(path)
-    basename != filename and URI.decode(basename) != filename and URI.encode(basename) != filename
+  defp media_proxy_opts do
+    Config.get([:media_proxy, :proxy_opts], [])
   end
 end
diff --git a/lib/pleroma/web/metadata/utils.ex b/lib/pleroma/web/metadata/utils.ex
index 2f0dfb474..8a206e019 100644
--- a/lib/pleroma/web/metadata/utils.ex
+++ b/lib/pleroma/web/metadata/utils.ex
@@ -38,7 +38,7 @@ defmodule Pleroma.Web.Metadata.Utils do
   def scrub_html(content), do: content
 
   def attachment_url(url) do
-    MediaProxy.url(url)
+    MediaProxy.preview_url(url)
   end
 
   def user_name_string(user) do
diff --git a/lib/pleroma/web/oauth/oauth_controller.ex b/lib/pleroma/web/oauth/oauth_controller.ex
index 26e68be42..a4152e840 100644
--- a/lib/pleroma/web/oauth/oauth_controller.ex
+++ b/lib/pleroma/web/oauth/oauth_controller.ex
@@ -119,7 +119,7 @@ defmodule Pleroma.Web.OAuth.OAuthController do
       redirect_uri = redirect_uri(conn, redirect_uri)
       url_params = %{access_token: token.token}
       url_params = Maps.put_if_present(url_params, :state, params["state"])
-      url = UriHelper.append_uri_params(redirect_uri, url_params)
+      url = UriHelper.modify_uri_params(redirect_uri, url_params)
       redirect(conn, external: url)
     else
       conn
@@ -161,7 +161,7 @@ defmodule Pleroma.Web.OAuth.OAuthController do
       redirect_uri = redirect_uri(conn, redirect_uri)
       url_params = %{code: auth.token}
       url_params = Maps.put_if_present(url_params, :state, auth_attrs["state"])
-      url = UriHelper.append_uri_params(redirect_uri, url_params)
+      url = UriHelper.modify_uri_params(redirect_uri, url_params)
       redirect(conn, external: url)
     else
       conn
diff --git a/lib/pleroma/web/router.ex b/lib/pleroma/web/router.ex
index cd336b932..f924e1e91 100644
--- a/lib/pleroma/web/router.ex
+++ b/lib/pleroma/web/router.ex
@@ -680,6 +680,8 @@ defmodule Pleroma.Web.Router do
   end
 
   scope "/proxy/", Pleroma.Web.MediaProxy do
+    get("/preview/:sig/:url", MediaProxyController, :preview)
+    get("/preview/:sig/:url/:filename", MediaProxyController, :preview)
     get("/:sig/:url", MediaProxyController, :remote)
     get("/:sig/:url/:filename", MediaProxyController, :remote)
   end