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diff --git a/lib/pleroma/web/web_finger.ex b/lib/pleroma/web/web_finger.ex
index f95dc2458..0d6a686c3 100644
--- a/lib/pleroma/web/web_finger.ex
+++ b/lib/pleroma/web/web_finger.ex
@@ -1,225 +1,241 @@
# Pleroma: A lightweight social networking server
# Copyright © 2017-2022 Pleroma Authors <https://pleroma.social/>
# SPDX-License-Identifier: AGPL-3.0-only
defmodule Pleroma.Web.WebFinger do
alias Pleroma.HTTP
alias Pleroma.User
alias Pleroma.Web.Endpoint
alias Pleroma.Web.Federator.Publisher
alias Pleroma.Web.XML
alias Pleroma.XmlBuilder
require Jason
require Logger
def host_meta do
base_url = Endpoint.url()
{
:XRD,
%{xmlns: "http://docs.oasis-open.org/ns/xri/xrd-1.0"},
{
:Link,
%{
rel: "lrdd",
type: "application/xrd+xml",
template: "#{base_url}/.well-known/webfinger?resource={uri}"
}
}
}
|> XmlBuilder.to_doc()
end
def webfinger(resource, fmt) when fmt in ["XML", "JSON"] do
host = Pleroma.Web.Endpoint.host()
regex =
if webfinger_domain = Pleroma.Config.get([__MODULE__, :domain]) do
~r/(acct:)?(?<username>[a-z0-9A-Z_\.-]+)@(#{host}|#{webfinger_domain})/
else
~r/(acct:)?(?<username>[a-z0-9A-Z_\.-]+)@#{host}/
end
with %{"username" => username} <- Regex.named_captures(regex, resource),
%User{} = user <- User.get_cached_by_nickname(username) do
{:ok, represent_user(user, fmt)}
else
_e ->
with %User{} = user <- User.get_cached_by_ap_id(resource) do
{:ok, represent_user(user, fmt)}
else
_e ->
{:error, "Couldn't find user"}
end
end
end
defp gather_links(%User{} = user) do
[
%{
"rel" => "http://webfinger.net/rel/profile-page",
"type" => "text/html",
"href" => user.ap_id
}
] ++ Publisher.gather_webfinger_links(user)
end
defp gather_aliases(%User{} = user) do
[user.ap_id | user.also_known_as]
end
def represent_user(user, "JSON") do
%{
"subject" => "acct:#{user.nickname}@#{domain()}",
"aliases" => gather_aliases(user),
"links" => gather_links(user)
}
end
def represent_user(user, "XML") do
aliases =
user
|> gather_aliases()
|> Enum.map(&{:Alias, &1})
links =
gather_links(user)
|> Enum.map(fn link -> {:Link, link} end)
{
:XRD,
%{xmlns: "http://docs.oasis-open.org/ns/xri/xrd-1.0"},
[
{:Subject, "acct:#{user.nickname}@#{domain()}"}
] ++ aliases ++ links
}
|> XmlBuilder.to_doc()
end
defp domain do
Pleroma.Config.get([__MODULE__, :domain]) || Pleroma.Web.Endpoint.host()
end
defp webfinger_from_xml(body) do
with {:ok, doc} <- XML.parse_document(body) do
subject = XML.string_from_xpath("//Subject", doc)
subscribe_address =
~s{//Link[@rel="http://ostatus.org/schema/1.0/subscribe"]/@template}
|> XML.string_from_xpath(doc)
ap_id =
~s{//Link[@rel="self" and @type="application/activity+json"]/@href}
|> XML.string_from_xpath(doc)
data = %{
"subject" => subject,
"subscribe_address" => subscribe_address,
"ap_id" => ap_id
}
{:ok, data}
end
end
defp webfinger_from_json(body) do
with {:ok, doc} <- Jason.decode(body) do
data =
Enum.reduce(doc["links"], %{"subject" => doc["subject"]}, fn link, data ->
case {link["type"], link["rel"]} do
{"application/activity+json", "self"} ->
Map.put(data, "ap_id", link["href"])
{"application/ld+json; profile=\"https://www.w3.org/ns/activitystreams\"", "self"} ->
Map.put(data, "ap_id", link["href"])
{nil, "http://ostatus.org/schema/1.0/subscribe"} ->
Map.put(data, "subscribe_address", link["template"])
_ ->
Logger.debug("Unhandled type: #{inspect(link["type"])}")
data
end
end)
{:ok, data}
end
end
def get_template_from_xml(body) do
xpath = "//Link[@rel='lrdd']/@template"
with {:ok, doc} <- XML.parse_document(body),
template when template != nil <- XML.string_from_xpath(xpath, doc) do
{:ok, template}
end
end
def find_lrdd_template(domain) do
# WebFinger is restricted to HTTPS - https://tools.ietf.org/html/rfc7033#section-9.1
meta_url = "https://#{domain}/.well-known/host-meta"
with {:ok, %{status: status, body: body}} when status in 200..299 <- HTTP.get(meta_url) do
get_template_from_xml(body)
else
error ->
Logger.warn("Can't find LRDD template in #{inspect(meta_url)}: #{inspect(error)}")
{:error, :lrdd_not_found}
end
end
defp get_address_from_domain(domain, encoded_account) when is_binary(domain) do
case find_lrdd_template(domain) do
{:ok, template} ->
String.replace(template, "{uri}", encoded_account)
_ ->
"https://#{domain}/.well-known/webfinger?resource=#{encoded_account}"
end
end
defp get_address_from_domain(_, _), do: {:error, :webfinger_no_domain}
@spec finger(String.t()) :: {:ok, map()} | {:error, any()}
def finger(account) do
account = String.trim_leading(account, "@")
domain =
with [_name, domain] <- String.split(account, "@") do
domain
else
_e ->
URI.parse(account).host
end
encoded_account = URI.encode("acct:#{account}")
with address when is_binary(address) <- get_address_from_domain(domain, encoded_account),
{:ok, %{status: status, body: body, headers: headers}} when status in 200..299 <-
HTTP.get(
address,
[{"accept", "application/xrd+xml,application/jrd+json"}]
) do
case List.keyfind(headers, "content-type", 0) do
{_, content_type} ->
case Plug.Conn.Utils.media_type(content_type) do
{:ok, "application", subtype, _} when subtype in ~w(xrd+xml xml) ->
webfinger_from_xml(body)
{:ok, "application", subtype, _} when subtype in ~w(jrd+json json) ->
webfinger_from_json(body)
_ ->
{:error, {:content_type, content_type}}
end
_ ->
{:error, {:content_type, nil}}
end
+ |> case do
+ {:ok, data} -> validate_webfinger(address, data)
+ error -> error
+ end
else
error ->
Logger.debug("Couldn't finger #{account}: #{inspect(error)}")
error
end
end
+
+ defp validate_webfinger(url, %{"subject" => "acct:" <> acct} = data) do
+ with %URI{host: request_host} <- URI.parse(url),
+ [_name, acct_host] <- String.split(acct, "@"),
+ {_, true} <- {:hosts_match, acct_host == request_host} do
+ {:ok, data}
+ else
+ _ -> {:error, {:webfinger_invalid, url, data}}
+ end
+ end
+
+ defp validate_webfinger(url, data), do: {:error, {:webfinger_invalid, url, data}}
end
diff --git a/test/fixtures/tesla_mock/gleasonator.com_host_meta b/test/fixtures/tesla_mock/gleasonator.com_host_meta
new file mode 100644
index 000000000..c1a432519
--- /dev/null
+++ b/test/fixtures/tesla_mock/gleasonator.com_host_meta
@@ -0,0 +1,4 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<XRD xmlns="http://docs.oasis-open.org/ns/xri/xrd-1.0">
+ <Link rel="lrdd" template="https://gleasonator.com/.well-known/webfinger?resource={uri}" type="application/xrd+xml" />
+</XRD>
\ No newline at end of file
diff --git a/test/fixtures/tesla_mock/webfinger_spoof.json b/test/fixtures/tesla_mock/webfinger_spoof.json
new file mode 100644
index 000000000..7c2a11f69
--- /dev/null
+++ b/test/fixtures/tesla_mock/webfinger_spoof.json
@@ -0,0 +1,28 @@
+{
+ "aliases": [
+ "https://gleasonator.com/users/alex",
+ "https://mitra.social/users/alex"
+ ],
+ "links": [
+ {
+ "href": "https://gleasonator.com/users/alex",
+ "rel": "http://webfinger.net/rel/profile-page",
+ "type": "text/html"
+ },
+ {
+ "href": "https://gleasonator.com/users/alex",
+ "rel": "self",
+ "type": "application/activity+json"
+ },
+ {
+ "href": "https://gleasonator.com/users/alex",
+ "rel": "self",
+ "type": "application/ld+json; profile=\"https://www.w3.org/ns/activitystreams\""
+ },
+ {
+ "rel": "http://ostatus.org/schema/1.0/subscribe",
+ "template": "https://gleasonator.com/ostatus_subscribe?acct={uri}"
+ }
+ ],
+ "subject": "acct:trump@whitehouse.gov"
+}
diff --git a/test/pleroma/web/web_finger_test.exs b/test/pleroma/web/web_finger_test.exs
index 6530fbc56..84a8e19d5 100644
--- a/test/pleroma/web/web_finger_test.exs
+++ b/test/pleroma/web/web_finger_test.exs
@@ -1,222 +1,230 @@
# Pleroma: A lightweight social networking server
# Copyright © 2017-2022 Pleroma Authors <https://pleroma.social/>
# SPDX-License-Identifier: AGPL-3.0-only
defmodule Pleroma.Web.WebFingerTest do
use Pleroma.DataCase, async: true
alias Pleroma.Web.WebFinger
import Pleroma.Factory
import Tesla.Mock
setup do
mock(fn env -> apply(HttpRequestMock, :request, [env]) end)
:ok
end
describe "host meta" do
test "returns a link to the xml lrdd" do
host_info = WebFinger.host_meta()
assert String.contains?(host_info, Pleroma.Web.Endpoint.url())
end
end
describe "incoming webfinger request" do
test "works for fqns" do
user = insert(:user)
{:ok, result} =
WebFinger.webfinger("#{user.nickname}@#{Pleroma.Web.Endpoint.host()}", "XML")
assert is_binary(result)
end
test "works for ap_ids" do
user = insert(:user)
{:ok, result} = WebFinger.webfinger(user.ap_id, "XML")
assert is_binary(result)
end
end
describe "fingering" do
test "returns error for nonsensical input" do
assert {:error, _} = WebFinger.finger("bliblablu")
assert {:error, _} = WebFinger.finger("pleroma.social")
end
test "returns error when there is no content-type header" do
Tesla.Mock.mock(fn
%{url: "https://social.heldscal.la/.well-known/host-meta"} ->
{:ok,
%Tesla.Env{
status: 200,
body: File.read!("test/fixtures/tesla_mock/social.heldscal.la_host_meta")
}}
%{
url:
"https://social.heldscal.la/.well-known/webfinger?resource=acct:invalid_content@social.heldscal.la"
} ->
{:ok, %Tesla.Env{status: 200, body: ""}}
end)
user = "invalid_content@social.heldscal.la"
assert {:error, {:content_type, nil}} = WebFinger.finger(user)
end
test "returns error when fails parse xml or json" do
user = "invalid_content@social.heldscal.la"
assert {:error, %Jason.DecodeError{}} = WebFinger.finger(user)
end
test "returns the ActivityPub actor URI for an ActivityPub user" do
user = "framasoft@framatube.org"
{:ok, _data} = WebFinger.finger(user)
end
- test "returns the ActivityPub actor URI and subscribe address for an ActivityPub user with the ld+json mimetype" do
- user = "kaniini@gerzilla.de"
-
- {:ok, data} = WebFinger.finger(user)
-
- assert data["ap_id"] == "https://gerzilla.de/channel/kaniini"
- assert data["subscribe_address"] == "https://gerzilla.de/follow?f=&url={uri}"
- end
-
test "it work for AP-only user" do
user = "kpherox@mstdn.jp"
{:ok, data} = WebFinger.finger(user)
assert data["magic_key"] == nil
assert data["salmon"] == nil
assert data["topic"] == nil
assert data["subject"] == "acct:kPherox@mstdn.jp"
assert data["ap_id"] == "https://mstdn.jp/users/kPherox"
assert data["subscribe_address"] == "https://mstdn.jp/authorize_interaction?acct={uri}"
end
- test "it works for friendica" do
- user = "lain@squeet.me"
-
- {:ok, _data} = WebFinger.finger(user)
- end
-
test "it gets the xrd endpoint" do
{:ok, template} = WebFinger.find_lrdd_template("social.heldscal.la")
assert template == "https://social.heldscal.la/.well-known/webfinger?resource={uri}"
end
test "it gets the xrd endpoint for hubzilla" do
{:ok, template} = WebFinger.find_lrdd_template("macgirvin.com")
assert template == "https://macgirvin.com/xrd/?uri={uri}"
end
test "it gets the xrd endpoint for statusnet" do
{:ok, template} = WebFinger.find_lrdd_template("status.alpicola.com")
assert template == "https://status.alpicola.com/main/xrd?uri={uri}"
end
test "it works with idna domains as nickname" do
nickname = "lain@" <> to_string(:idna.encode("zetsubou.みんな"))
{:ok, _data} = WebFinger.finger(nickname)
end
test "it works with idna domains as link" do
ap_id = "https://" <> to_string(:idna.encode("zetsubou.みんな")) <> "/users/lain"
{:ok, _data} = WebFinger.finger(ap_id)
end
test "respects json content-type" do
Tesla.Mock.mock(fn
%{
url:
"https://mastodon.social/.well-known/webfinger?resource=acct:emelie@mastodon.social"
} ->
{:ok,
%Tesla.Env{
status: 200,
body: File.read!("test/fixtures/tesla_mock/webfinger_emelie.json"),
headers: [{"content-type", "application/jrd+json"}]
}}
%{url: "https://mastodon.social/.well-known/host-meta"} ->
{:ok,
%Tesla.Env{
status: 200,
body: File.read!("test/fixtures/tesla_mock/mastodon.social_host_meta")
}}
end)
{:ok, _data} = WebFinger.finger("emelie@mastodon.social")
end
test "respects xml content-type" do
Tesla.Mock.mock(fn
%{
url: "https://pawoo.net/.well-known/webfinger?resource=acct:pekorino@pawoo.net"
} ->
{:ok,
%Tesla.Env{
status: 200,
body: File.read!("test/fixtures/tesla_mock/https___pawoo.net_users_pekorino.xml"),
headers: [{"content-type", "application/xrd+xml"}]
}}
%{url: "https://pawoo.net/.well-known/host-meta"} ->
{:ok,
%Tesla.Env{
status: 200,
body: File.read!("test/fixtures/tesla_mock/pawoo.net_host_meta")
}}
end)
{:ok, _data} = WebFinger.finger("pekorino@pawoo.net")
end
test "refuses to process XML remote entities" do
Tesla.Mock.mock(fn
%{
url: "https://pawoo.net/.well-known/webfinger?resource=acct:pekorino@pawoo.net"
} ->
{:ok,
%Tesla.Env{
status: 200,
body: File.read!("test/fixtures/xml_external_entities.xml"),
headers: [{"content-type", "application/xrd+xml"}]
}}
%{url: "https://pawoo.net/.well-known/host-meta"} ->
{:ok,
%Tesla.Env{
status: 200,
body: File.read!("test/fixtures/tesla_mock/pawoo.net_host_meta")
}}
end)
assert :error = WebFinger.finger("pekorino@pawoo.net")
end
+
+ test "prevents spoofing" do
+ Tesla.Mock.mock(fn
+ %{
+ url: "https://gleasonator.com/.well-known/webfinger?resource=acct:alex@gleasonator.com"
+ } ->
+ {:ok,
+ %Tesla.Env{
+ status: 200,
+ body: File.read!("test/fixtures/tesla_mock/webfinger_spoof.json"),
+ headers: [{"content-type", "application/jrd+json"}]
+ }}
+
+ %{url: "https://gleasonator.com/.well-known/host-meta"} ->
+ {:ok,
+ %Tesla.Env{
+ status: 200,
+ body: File.read!("test/fixtures/tesla_mock/gleasonator.com_host_meta")
+ }}
+ end)
+
+ {:error, _data} = WebFinger.finger("alex@gleasonator.com")
+ end
end
test "prevents forgeries" do
Tesla.Mock.mock(fn
%{url: "https://fba.ryona.agency/.well-known/webfinger?resource=acct:graf@fba.ryona.agency"} ->
fake_webfinger =
File.read!("test/fixtures/webfinger/graf-imposter-webfinger.json") |> Jason.decode!()
Tesla.Mock.json(fake_webfinger)
%{url: "https://fba.ryona.agency/.well-known/host-meta"} ->
{:ok, %Tesla.Env{status: 404}}
end)
refute {:ok, _} = WebFinger.finger("graf@fba.ryona.agency")
end
end

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