refactor(10.2-01): nest framework packages under modules

- Move remaining beach packages and embedded admin assets\n- Rewrite framework, example, build, and gate paths

modules/surf/clientip_test.go

@@ -0,0 +1,59 @@
+package surf
+
+import (
+	"net/http"
+	"net/http/httptest"
+	"net/netip"
+	"testing"
+)
+
+func TestClientIPEmptyTrustedUsesRemoteAddr(t *testing.T) {
+	req := httptest.NewRequest(http.MethodGet, "/", nil)
+	req.RemoteAddr = "203.0.113.9:1234"
+	req.Header.Set("X-Forwarded-For", "198.51.100.1")
+	got := ClientIP(req, nil)
+	if got != "203.0.113.9" {
+		t.Fatalf("got %q", got)
+	}
+}
+
+func TestClientIPRejectsSpoofedXFF(t *testing.T) {
+	trusted := []netip.Prefix{mustPrefix("10.0.0.0/8")}
+	req := httptest.NewRequest(http.MethodGet, "/", nil)
+	req.RemoteAddr = "203.0.113.9:1234"
+	req.Header.Set("X-Forwarded-For", "198.51.100.1")
+	got := ClientIP(req, trusted)
+	if got != "203.0.113.9" {
+		t.Fatalf("untrusted RemoteAddr must ignore X-Forwarded-For, got %q", got)
+	}
+}
+
+func TestClientIPRightmostUntrustedHop(t *testing.T) {
+	trusted := []netip.Prefix{mustPrefix("10.0.0.0/8")}
+	req := httptest.NewRequest(http.MethodGet, "/", nil)
+	req.RemoteAddr = "10.0.0.1:443"
+	req.Header.Set("X-Forwarded-For", "198.51.100.7, 203.0.113.10, 10.0.0.2")
+	got := ClientIP(req, trusted)
+	if got != "203.0.113.10" {
+		t.Fatalf("rightmost untrusted hop = %q", got)
+	}
+}
+
+func TestClientIPAllHopsTrustedFallsBack(t *testing.T) {
+	trusted := []netip.Prefix{mustPrefix("10.0.0.0/8")}
+	req := httptest.NewRequest(http.MethodGet, "/", nil)
+	req.RemoteAddr = "10.0.0.1:443"
+	req.Header.Set("X-Forwarded-For", "10.0.0.8, 10.0.0.9")
+	got := ClientIP(req, trusted)
+	if got != "10.0.0.1" {
+		t.Fatalf("fallback RemoteAddr = %q", got)
+	}
+}
+
+func mustPrefix(s string) netip.Prefix {
+	p, err := netip.ParsePrefix(s)
+	if err != nil {
+		panic(err)
+	}
+	return p
+}