refactor(tracking): remove unused src image proxy

The /img/<server>/<message> endpoint accepted a src=<url> query parameter and proxied the body of that URL back to the caller. Nothing in the codebase ever produces a src= parameter — the parser only inserts a plain tracking pixel and rewrites href links — so this branch is dead code inherited from the original AppMail import. Drop the src branch: requests with src now return 400. The no-src path that serves the tracking pixel and records loads is unchanged, and a spec covers both the pixel-serving path and the removed branch.
2026-05-31 04:35:42 +00:00 · 2026-04-24 22:24:18 +01:00
--- a/spec/lib/tracking_middleware_spec.rb
+++ b/spec/lib/tracking_middleware_spec.rb
@@ -0,0 +1,71 @@
+# frozen_string_literal: true
+
+require "rails_helper"
+require "rack/test"
+
+RSpec.describe TrackingMiddleware do
+  include Rack::Test::Methods
+
+  let(:inner_app) { ->(_env) { [200, {}, ["inner"]] } }
+  let(:app) { described_class.new(inner_app) }
+
+  let(:server) { create(:server) }
+  let(:message) do
+    MessageFactory.incoming(server) do |_msg, mail|
+      mail.html_part = Mail::Part.new do
+        content_type "text/html; charset=UTF-8"
+        body "<html><body>hi</body></html>"
+      end
+    end
+  end
+
+  def track_headers
+    { "HTTP_X_POSTAL_TRACK_HOST" => "1" }
+  end
+
+  describe "GET /img/:server_token/:message_token (open tracking pixel)" do
+    before do
+      get "/img/#{server.token}/#{message.token}", {}, track_headers
+    end
+
+    it "returns the tracking pixel PNG" do
+      expect(last_response.status).to eq 200
+      expect(last_response.headers["Content-Type"]).to eq "image/png"
+      expect(last_response.body.bytesize).to be > 0
+    end
+
+    it "records a load for the message" do
+      # Re-fetch the message so loads are read fresh from the DB.
+      reloaded = server.message_db.message(message.id)
+      expect(reloaded.loads.size).to eq 1
+    end
+  end
+
+  describe "GET /img/:server_token/:message_token?src=<url> (image proxy)" do
+    let(:attacker_url) { "http://internal.example.com/secret" }
+
+    before do
+      stub_request(:get, attacker_url).to_return(status: 200, body: "internal-secret")
+    end
+
+    it "does not fetch the URL and returns 400" do
+      get "/img/#{server.token}/#{message.token}", { src: attacker_url }, track_headers
+
+      expect(last_response.status).to eq 400
+      expect(WebMock).not_to have_requested(:get, attacker_url)
+    end
+
+    it "does not fetch the URL even when the message token is invalid" do
+      get "/img/#{server.token}/nonexistent", { src: attacker_url }, track_headers
+
+      expect(WebMock).not_to have_requested(:get, attacker_url)
+    end
+  end
+
+  describe "when the track-host header is missing" do
+    it "passes the request through to the inner app untouched" do
+      get "/img/#{server.token}/#{message.token}"
+      expect(last_response.body).to eq "inner"
+    end
+  end
+end