fix(http): make Hackney trust the CAStore bundle

Hackney trusts its own certifi bundle, which still has the roots of the
compromised eMudhra intermediate CAs. Pass explicit ssl_options with the
CAStore bundle. Hackney drops all its TLS defaults when ssl_options are
given, so keep peer and hostname checks in the options.

test/pleroma/http/adapter_helper/hackney_test.exs

@@ -39,5 +39,20 @@ defmodule Pleroma.HTTP.AdapterHelper.HackneyTest do
       assert opts[:b] == 1
       refute Keyword.has_key?(opts, :proxy)
     end
+
+    test "trusts the CAStore bundle", %{uri: uri} do
+      opts = Hackney.options([], uri)
+
+      assert opts[:ssl_options] == Pleroma.HTTP.TLS.ssl_options()
+    end
+
+    test "keeps the CAStore bundle with configured ssl_options", %{uri: uri} do
+      clear_config([:http, :adapter], ssl_options: [versions: [:"tlsv1.2"]])
+
+      opts = Hackney.options([], uri)
+
+      assert opts[:ssl_options][:versions] == [:"tlsv1.2"]
+      assert opts[:ssl_options][:cacertfile] == CAStore.file_path()
+    end
   end
 end

test/pleroma/http/tls_test.exs

@@ -0,0 +1,47 @@
+# Pleroma: A lightweight social networking server
+# Copyright © 2017-2022 Pleroma Authors <https://pleroma.social/>
+# SPDX-License-Identifier: AGPL-3.0-only
+
+defmodule Pleroma.HTTP.TLSTest do
+  use ExUnit.Case, async: true
+
+  alias Pleroma.HTTP.TLS
+
+  describe "ssl_options/1" do
+    test "verifies peers against the CAStore bundle" do
+      opts = TLS.ssl_options()
+
+      assert opts[:verify] == :verify_peer
+      assert opts[:cacertfile] == CAStore.file_path()
+      assert [match_fun: match_fun] = opts[:customize_hostname_check]
+      assert is_function(match_fun, 2)
+    end
+
+    test "keeps the CA bundle when other options are given" do
+      opts = TLS.ssl_options(versions: [:"tlsv1.2"])
+
+      assert opts[:versions] == [:"tlsv1.2"]
+      assert opts[:cacertfile] == CAStore.file_path()
+      assert opts[:verify] == :verify_peer
+    end
+  end
+
+  describe "put_hackney_ssl_options/1" do
+    test "adds the TLS options" do
+      opts = TLS.put_hackney_ssl_options(pool: :media)
+
+      assert opts[:pool] == :media
+      assert opts[:ssl_options] == TLS.ssl_options()
+    end
+
+    test "merges given ssl_options into the TLS options" do
+      opts = TLS.put_hackney_ssl_options(ssl_options: [versions: [:"tlsv1.2"]])
+
+      assert opts[:ssl_options] == TLS.ssl_options(versions: [:"tlsv1.2"])
+    end
+
+    test "leaves insecure requests alone" do
+      assert TLS.put_hackney_ssl_options(insecure: true) == [insecure: true]
+    end
+  end
+end