From 10b4c43bd2b21f04cecca1ce0603dd9808463b79 Mon Sep 17 00:00:00 2001
From: Mathias <mthbqv@gmail.com>
Date: Sat, 3 Oct 2026 20:55:00 +0200
Subject: [PATCH] test(web): foreign-origin POSTs must be refused by the router
 (#48), red

Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>
---
 internal/web/crossorigin_test.go | 137 +++++++++++++++++++++++++++++++
 1 file changed, 137 insertions(+)
 create mode 100644 internal/web/crossorigin_test.go

diff --git a/internal/web/crossorigin_test.go b/internal/web/crossorigin_test.go
new file mode 100644
index 0000000..0d5e915
--- /dev/null
+++ b/internal/web/crossorigin_test.go
@@ -0,0 +1,137 @@
+package web_test
+
+// Observes the cross-origin gate around Router (#48): SameSite=Lax does not stop a POST
+// from a sibling *.d-ma.be origin, so the router itself must refuse a non-safe request
+// whose Origin or Sec-Fetch-Site says it did not come from this site's own pages.
+
+import (
+	"context"
+	"net/http"
+	"net/http/httptest"
+	"net/url"
+	"strings"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+)
+
+// foreign is a header set a browser sends for a form post made by another page.
+var foreign = map[string]map[string]string{
+	"sibling subdomain, Sec-Fetch-Site": {"Origin": "https://evil.d-ma.be", "Sec-Fetch-Site": "same-site"},
+	"other site, Sec-Fetch-Site":        {"Origin": "https://evil.example", "Sec-Fetch-Site": "cross-site"},
+	"sibling subdomain, Origin only":    {"Origin": "https://evil.d-ma.be"},
+	"opaque origin":                     {"Origin": "null"},
+}
+
+// own is a header set for the app's own pages (or a non-browser client): must pass.
+var own = map[string]map[string]string{
+	"same-origin Sec-Fetch-Site": {"Sec-Fetch-Site": "same-origin", "Origin": "http://example.com"},
+	"matching Origin only":       {"Origin": "http://example.com"},
+	"no browser headers":         {},
+}
+
+func withHeaders(req *http.Request, h map[string]string) *http.Request {
+	for k, v := range h {
+		req.Header.Set(k, v)
+	}
+	return req
+}
+
+func userCount(t *testing.T) int {
+	t.Helper()
+	var n int
+	require.NoError(t, rawPool(t).QueryRow(context.Background(), `SELECT count(*) FROM users WHERE id = $1`, userID).Scan(&n))
+	return n
+}
+
+func TestCrossOrigin_ARefusedDeleteAccountPostLeavesTheAccountInPlace(t *testing.T) {
+	for name, h := range foreign {
+		t.Run(name, func(t *testing.T) {
+			app, _ := newAccountApp(t)
+			resetDB(t, rawPool(t))
+			seedConnection(t, app, "youtube", "ada@channel", "ref")
+
+			rec := do(t, app, withHeaders(httptest.NewRequest(http.MethodPost, "/account/delete", nil), h))
+
+			assert.Equal(t, http.StatusForbidden, rec.Code)
+			assert.Equal(t, 1, userCount(t), "the account must survive a refused post")
+		})
+	}
+}
+
+func TestCrossOrigin_ASameOriginOrHeaderlessDeleteAccountPostIsServed(t *testing.T) {
+	for name, h := range own {
+		t.Run(name, func(t *testing.T) {
+			app, _ := newAccountApp(t)
+			resetDB(t, rawPool(t))
+			seedConnection(t, app, "youtube", "ada@channel", "ref")
+
+			rec := do(t, app, withHeaders(httptest.NewRequest(http.MethodPost, "/account/delete", nil), h))
+
+			assert.Equal(t, http.StatusSeeOther, rec.Code)
+			assert.Equal(t, "/auth/logout", rec.Header().Get("Location"))
+		})
+	}
+}
+
+func TestCrossOrigin_ARefusedUploadPostSubmitsNoJob(t *testing.T) {
+	for name, h := range foreign {
+		t.Run(name, func(t *testing.T) {
+			app, sub := newUploadApp(t, audioOK, 200<<20)
+
+			rec := do(t, app, withHeaders(uploadReq(t, "m", "m.wav", []byte("RIFF....WAVE")), h))
+
+			assert.Equal(t, http.StatusForbidden, rec.Code)
+			assert.Empty(t, sub.jobs, "a refused post must not enqueue transcription")
+		})
+	}
+}
+
+func TestCrossOrigin_ARefusedUploadChatPostCallsNoModel(t *testing.T) {
+	for name, h := range foreign {
+		t.Run(name, func(t *testing.T) {
+			app, fc := newUploadChatApp(t)
+			id := seedUpload(t, userID, "Roadmap sync", "done", meetingText)
+
+			req := chatPost("/uploads/"+id+"/chat", url.Values{"message": {"hej"}})
+			rec := do(t, app, withHeaders(req, h))
+
+			assert.Equal(t, http.StatusForbidden, rec.Code)
+			assert.Zero(t, fc.callCount)
+		})
+	}
+}
+
+func TestCrossOrigin_AForeignPostIsRefusedOnEachListedStateChangingPath(t *testing.T) {
+	routes := []string{
+		"/account/disconnect/youtube",
+		"/account/summarize-mode",
+		"/register",
+		"/paste",
+		"/v/abc/action",
+		"/v/abc/summarize",
+		"/v/abc/retry-now",
+		"/v/abc/chat",
+	}
+	for _, path := range routes {
+		t.Run(path, func(t *testing.T) {
+			app := newApp(t)
+			req := httptest.NewRequest(http.MethodPost, path, strings.NewReader(""))
+			req.Header.Set("Content-Type", "application/x-www-form-urlencoded")
+			rec := do(t, app, withHeaders(req, foreign["sibling subdomain, Sec-Fetch-Site"]))
+			assert.Equal(t, http.StatusForbidden, rec.Code)
+		})
+	}
+}
+
+// A login redirect comes back to /auth/callback as a cross-site GET navigation, and
+// health probes carry no headers: safe methods must never be refused on origin grounds.
+func TestCrossOrigin_ACrossSiteGETIsNotRefused(t *testing.T) {
+	app := newApp(t)
+	for _, path := range []string{"/healthz", "/welcome"} {
+		req := httptest.NewRequest(http.MethodGet, path, nil)
+		req.Header.Set("Sec-Fetch-Site", "cross-site")
+		assert.Equal(t, http.StatusOK, do(t, app, req).Code, path)
+	}
+}