oceanmedia: fix segment endpoint redirecting to old segments

cmd/oceanmedia/playlist_test.go

@@ -39,6 +39,7 @@ import (
 	"github.com/ausocean/cloud/gauth"
 	"github.com/ausocean/cloud/model"
 	"github.com/gofiber/fiber/v2"
+	"github.com/gofiber/fiber/v2/utils"
 	"github.com/stretchr/testify/assert"
 	"github.com/stretchr/testify/require"
 )
@@ -221,6 +222,25 @@ func TestServerSignURLCache(t *testing.T) {
 	assert.Equal(t, 2, cs.callCount())
 }
 
+// TestServerSignURLCacheDoesNotAliasUnsafeKeys repeatedly passes a zero-copy
+// string to the cache while mutating its backing buffer, as Fiber does when it
+// reuses a request buffer. Every URI is distinct, so every call must sign a new
+// URL rather than hitting an entry whose key was mutated to look like it.
+func TestServerSignURLCacheDoesNotAliasUnsafeKeys(t *testing.T) {
+	cs := &countingSigner{}
+	s := newServer(nil, cs, testJWTSecret, time.Hour)
+
+	const n = 4096
+	buf := make([]byte, len("https://example.com/bucket/00000000.ts"))
+	for i := 0; i < n; i++ {
+		copy(buf, fmt.Sprintf("https://example.com/bucket/%08x.ts", i))
+		_, err := s.signURL(context.Background(), utils.UnsafeString(buf))
+		require.NoError(t, err)
+	}
+
+	assert.Equal(t, n, cs.callCount())
+}
+
 func newTestApp(s *server) *fiber.App {
 	app := fiber.New()
 	app.Get("/segment", s.handleSegment)

cmd/oceanmedia/server.go

@@ -27,6 +27,7 @@ package main
 import (
 	"context"
 	"log"
+	"strings"
 	"sync"
 	"time"
 
@@ -109,6 +110,11 @@ func newServer(store datastore.Store, signer urlSigner, jwtSecret []byte, signed
 // signURL returns a pre-signed URL for the given storage URI, caching the
 // result until half the signed URL time to live has elapsed.
 func (s *server) signURL(ctx context.Context, rawURI string) (string, error) {
+	// rawURI may be a zero-copy string owned by the request context (for
+	// example fiber.Ctx.Query). It is used as a map key, which outlives the
+	// request, so copy it first. Otherwise the request buffer can be reused
+	// and mutate the key, causing every lookup to hit the same cached URL.
+	rawURI = strings.Clone(rawURI)
 	now := s.now()
 
 	s.signMu.Lock()