From 4e5aa3b3a0c0c90ef42aadfb3eaf415955cf86b2 Mon Sep 17 00:00:00 2001
From: lain <lain@soykaf.club>
Date: Sat, 31 Mar 2018 17:51:33 +0200
Subject: [PATCH] Add gopher server.

---
 config/config.exs            |   5 ++
 lib/pleroma/application.ex   |   1 +
 lib/pleroma/gopher/server.ex | 142 +++++++++++++++++++++++++++++++++++
 3 files changed, 148 insertions(+)
 create mode 100644 lib/pleroma/gopher/server.ex

diff --git a/config/config.exs b/config/config.exs
index fc8067b49..151c6b826 100644
--- a/config/config.exs
+++ b/config/config.exs
@@ -64,6 +64,11 @@
 
 config :phoenix, :format_encoders, json: Jason
 
+config :pleroma, :gopher,
+  enabled: false,
+  ip: {0, 0, 0, 0},
+  port: 9999
+
 # Import environment specific config. This must remain at the bottom
 # of this file so it overrides the configuration defined above.
 import_config "#{Mix.env()}.exs"
diff --git a/lib/pleroma/application.ex b/lib/pleroma/application.ex
index 5e29a5d65..89826f515 100644
--- a/lib/pleroma/application.ex
+++ b/lib/pleroma/application.ex
@@ -24,6 +24,7 @@ def start(_type, _args) do
           ]
         ]),
         worker(Pleroma.Web.Federator, []),
+        worker(Pleroma.Gopher.Server, []),
         worker(Pleroma.Stats, [])
       ] ++
         if Mix.env() == :test,
diff --git a/lib/pleroma/gopher/server.ex b/lib/pleroma/gopher/server.ex
new file mode 100644
index 000000000..cccde155a
--- /dev/null
+++ b/lib/pleroma/gopher/server.ex
@@ -0,0 +1,142 @@
+defmodule Pleroma.Gopher.Server do
+  use GenServer
+  require Logger
+  @gopher Application.get_env(:pleroma, :gopher)
+
+  def start_link() do
+    ip = Keyword.get(@gopher, :ip, {0, 0, 0, 0})
+    port = Keyword.get(@gopher, :port, 1234)
+    GenServer.start_link(__MODULE__, [ip, port], [])
+  end
+
+  def init([ip, port]) do
+    if Keyword.get(@gopher, :enabled, false) do
+      Logger.info("Starting gopher server on #{port}")
+
+      :ranch.start_listener(
+        :gopher,
+        100,
+        :ranch_tcp,
+        [port: port],
+        __MODULE__.ProtocolHandler,
+        []
+      )
+
+      {:ok, %{ip: ip, port: port}}
+    else
+      Logger.info("Gopher server disabled")
+      {:ok, nil}
+    end
+  end
+end
+
+defmodule Pleroma.Gopher.Server.ProtocolHandler do
+  alias Pleroma.Web.ActivityPub.ActivityPub
+  alias Pleroma.User
+  alias Pleroma.Activity
+  alias Pleroma.Repo
+
+  @instance Application.get_env(:pleroma, :instance)
+  @gopher Application.get_env(:pleroma, :gopher)
+
+  def start_link(ref, socket, transport, opts) do
+    pid = spawn_link(__MODULE__, :init, [ref, socket, transport, opts])
+    {:ok, pid}
+  end
+
+  def init(ref, socket, transport, _Opts = []) do
+    :ok = :ranch.accept_ack(ref)
+    loop(socket, transport)
+  end
+
+  def info(text) do
+    "#{text}\tfake\(NULL)\t0\r\n"
+  end
+
+  def link(name, selector, type \\ 1) do
+    address = Pleroma.Web.Endpoint.host()
+    port = Keyword.get(@gopher, :port, 1234)
+    "#{type}#{name}\t#{selector}\t#{address}\t#{port}\r\n"
+  end
+
+  def response("") do
+    info("Welcome to #{Keyword.get(@instance, :name, "Pleroma")}!") <>
+      link("Public Timeline", "/main/public") <>
+      link("Federated Timeline", "/main/all") <> ".\r\n"
+  end
+
+  def render_activities(activities) do
+    activities
+    |> Enum.reverse()
+    |> Enum.map(fn activity ->
+      user = User.get_cached_by_ap_id(activity.data["actor"])
+
+      link("Post ##{activity.id} by #{user.nickname}", "/notices/#{activity.id}") <>
+        info(HtmlSanitizeEx.strip_tags(activity.data["object"]["content"]))
+    end)
+    |> Enum.join("\r\n")
+  end
+
+  def response("/main/public") do
+    posts =
+      ActivityPub.fetch_public_activities(%{"type" => ["Create"], "local_only" => true})
+      |> render_activities
+
+    info("Welcome to the Public Timeline!") <> posts <> ".\r\n"
+  end
+
+  def response("/main/all") do
+    posts =
+      ActivityPub.fetch_public_activities(%{"type" => ["Create"]})
+      |> render_activities
+
+    info("Welcome to the Federated Timeline!") <> posts <> ".\r\n"
+  end
+
+  def response("/notices/" <> id) do
+    with %Activity{} = activity <- Repo.get(Activity, id),
+         true <- ActivityPub.is_public?(activity) do
+      activities =
+        ActivityPub.fetch_activities_for_context(activity.data["context"])
+        |> render_activities
+
+      user = User.get_cached_by_ap_id(activity.data["actor"])
+
+      info("Post #{activity.id} by #{user.nickname}") <>
+        link("More posts by #{user.nickname}", "/users/#{user.nickname}") <> activities <> ".\r\n"
+    else
+      _e ->
+        info("Not public") <> ".\r\n"
+    end
+  end
+
+  def response("/users/" <> nickname) do
+    with %User{} = user <- User.get_cached_by_nickname(nickname) do
+      params = %{
+        "type" => ["Create"],
+        "actor_id" => user.ap_id
+      }
+
+      activities =
+        ActivityPub.fetch_public_activities(params)
+        |> render_activities
+
+      info("Posts by #{user.nickname}") <> activities <> ".\r\n"
+    else
+      _e ->
+        info("No such user") <> ".\r\n"
+    end
+  end
+
+  def loop(socket, transport) do
+    case transport.recv(socket, 0, 5000) do
+      {:ok, data} ->
+        data = String.trim_trailing(data, "\r\n")
+        transport.send(socket, response(data))
+        :ok = transport.close(socket)
+
+      _ ->
+        :ok = transport.close(socket)
+    end
+  end
+end