🐛 bug: Fix Cache middleware handling of Age (#3547)

* Revert benchmark loop changes

* test: cover Age header parsing

* generate msgp files

* Update cache.go

* Cast result

* Update cache.go

Author: gaby

ctx_interface_gen.go

@@ -26,7 +26,6 @@ This middleware caches responses with the following status codes according to RF
 - `414: URI Too Long`
 - `501: Not Implemented`
 
-Additionally, `418: I'm a teapot` is not originally cacheable but is cached by this middleware.
 If the status code is other than these, you will always get an `unreachable` cache status.
 
 For more information about cacheable status codes or RFC7231, please refer to the following resources:

docs/middleware/cache.md

@@ -12,6 +12,7 @@ import (
 
 	"github.com/gofiber/fiber/v3"
 	"github.com/gofiber/utils/v2"
+	"github.com/valyala/fasthttp"
 )
 
 // timestampUpdatePeriod is the period which is used to check the cache expiration.
@@ -59,7 +60,6 @@ var cacheableStatusCodes = map[int]bool{
 	fiber.StatusMethodNotAllowed:            true,
 	fiber.StatusGone:                        true,
 	fiber.StatusRequestURITooLong:           true,
-	fiber.StatusTeapot:                      true,
 	fiber.StatusNotImplemented:              true,
 }
 
@@ -168,8 +168,9 @@ func New(config ...Config) fiber.Handler {
 					c.Set(fiber.HeaderCacheControl, "public, max-age="+maxAge)
 				}
 
-				// RFC-compliant Age header
-				age := strconv.FormatUint(e.ttl-(e.exp-ts), 10)
+				// RFC-compliant Age header (RFC 9111)
+				resident := e.ttl - (e.exp - ts)
+				age := strconv.FormatUint(e.age+resident, 10)
 				c.Response().Header.Set(fiber.HeaderAge, age)
 
 				c.Set(cfg.CacheHeader, cacheHit)
@@ -239,9 +240,15 @@ func New(config ...Config) fiber.Handler {
 		e.ctype = utils.CopyBytes(c.Response().Header.ContentType())
 		e.cencoding = utils.CopyBytes(c.Response().Header.Peek(fiber.HeaderContentEncoding))
 
-		if len(c.Response().Header.Peek(fiber.HeaderAge)) == 0 {
+		ageVal := uint64(0)
+		if b := c.Response().Header.Peek(fiber.HeaderAge); len(b) > 0 {
+			if v, err := fasthttp.ParseUint(b); err == nil {
+				ageVal = uint64(v) //nolint:gosec //Not a concern
+			}
+		} else {
 			c.Response().Header.Set(fiber.HeaderAge, "0")
 		}
+		e.age = ageVal
 
 		// Store all response headers
 		// (more: https://datatracker.ietf.org/doc/html/rfc2616#section-13.5.1)

middleware/cache/cache.go

@@ -1050,6 +1050,7 @@ func Test_Cache_UncacheableStatusCodes(t *testing.T) {
 		fiber.StatusPreconditionRequired,
 		fiber.StatusTooManyRequests,
 		fiber.StatusRequestHeaderFieldsTooLarge,
+		fiber.StatusTeapot,
 		fiber.StatusUnavailableForLegalReasons,
 
 		// Server error responses
@@ -1092,6 +1093,29 @@ func TestCacheAgeHeader(t *testing.T) {
 	require.Positive(t, age)
 }
 
+func TestCacheUpstreamAge(t *testing.T) {
+	t.Parallel()
+	app := fiber.New()
+	app.Use(New(Config{Expiration: 3 * time.Second}))
+	app.Get("/", func(c fiber.Ctx) error {
+		c.Set(fiber.HeaderAge, "5")
+		return c.SendString("hi")
+	})
+
+	resp, err := app.Test(httptest.NewRequest(fiber.MethodGet, "/", nil))
+	require.NoError(t, err)
+	require.Equal(t, "5", resp.Header.Get(fiber.HeaderAge))
+
+	time.Sleep(1500 * time.Millisecond)
+
+	resp, err = app.Test(httptest.NewRequest(fiber.MethodGet, "/", nil))
+	require.NoError(t, err)
+	require.Equal(t, cacheHit, resp.Header.Get("X-Cache"))
+	age, err := strconv.Atoi(resp.Header.Get(fiber.HeaderAge))
+	require.NoError(t, err)
+	require.GreaterOrEqual(t, age, 6)
+}
+
 func Test_CacheNoStoreDirective(t *testing.T) {
 	t.Parallel()
 	app := fiber.New()

middleware/cache/cache_test.go

@@ -17,6 +17,7 @@ type item struct {
 	ctype     []byte
 	cencoding []byte
 	status    int
+	age       uint64
 	exp       uint64
 	ttl       uint64
 	// used for finding the item in an indexed heap
@@ -63,7 +64,9 @@ func (m *manager) release(e *item) {
 	e.body = nil
 	e.ctype = nil
 	e.status = 0
+	e.age = 0
 	e.exp = 0
+	e.ttl = 0
 	e.headers = nil
 	m.pool.Put(e)
 }