Fix parsing of x-forwarded-for header

lib/opentelemetry_phoenix.ex

@@ -195,12 +195,16 @@ defmodule OpentelemetryPhoenix do
  end
 
  defp client_ip(%{remote_ip: remote_ip} = conn) do
- case Plug.Conn.get_req_header(conn, "x-forwarded-for") do
- [] ->
- to_string(:inet_parse.ntoa(remote_ip))
-
- [client | _] ->
- client
+ case header_value(conn, "x-forwarded-for") do
+ "" ->
+ remote_ip
+ |> :inet_parse.ntoa()
+ |> to_string()
+
+ ip_address ->
+ ip_address
+ |> String.split(",", parts: 2)
+ |> List.first("")
  end
  end
 

test/opentelemetry_phoenix_test.exs

@@ -78,6 +78,26 @@ defmodule OpentelemetryPhoenixTest do
  ] == List.keysort(list, 0)
  end
 
+ test "parses x-forwarded-for with single value" do
+ OpentelemetryPhoenix.setup()
+
+ x_forwarded_for_request("203.0.113.195")
+
+ assert_receive {:span, span(attributes: list)}
+
+ assert Keyword.fetch!(list, :"http.client_ip") == "203.0.113.195"
+ end
+
+ test "parses x-forwarded-for with multiple values" do
+ OpentelemetryPhoenix.setup()
+
+ x_forwarded_for_request("203.0.113.195, 70.41.3.18, 150.172.238.178")
+
+ assert_receive {:span, span(attributes: list)}
+
+ assert Keyword.fetch!(list, :"http.client_ip") == "203.0.113.195"
+ end
+
  test "records exceptions for Phoenix web requests" do
  OpentelemetryPhoenix.setup()
 
@@ -215,4 +235,28 @@ defmodule OpentelemetryPhoenixTest do
  "phoenix.plug": MyStoreWeb.PageController
  ] == List.keysort(list, 0)
  end
+
+ defp x_forwarded_for_request(x_forwarded_for) do
+ meta = Meta.endpoint_start()
+
+ meta = %{
+ meta
+ | conn: %{
+ meta.conn
+ | req_headers: [{"x-forwarded-for", x_forwarded_for} | meta.conn.req_headers]
+ }
+ }
+
+ :telemetry.execute(
+ [:phoenix, :endpoint, :start],
+ %{system_time: System.system_time()},
+ meta
+ )
+
+ :telemetry.execute(
+ [:phoenix, :endpoint, :stop],
+ %{duration: 444},
+ Meta.endpoint_stop()
+ )
+ end
 end