feat(ogtags): when encountering opengraph URLs, add them to an allow cache

Signed-off-by: Xe Iaso <me@xeiaso.net>

internal/ogtags/cache.go

@@ -5,7 +5,9 @@ import (
 	"errors"
 	"log/slog"
 	"net/url"
+	"strings"
 	"syscall"
+	"time"
 )
 
 // GetOGTags is the main function that retrieves Open Graph tags for a URL
@@ -45,6 +47,18 @@ func (c *OGTagCache) GetOGTags(ctx context.Context, url *url.URL, originalHost s
 	// Store in cache
 	c.cache.Set(ctx, cacheKey, ogTags, c.ogTimeToLive)
 
+	for k, v := range ogTags {
+		switch {
+		case strings.HasSuffix(k, "image"), strings.HasSuffix(k, "audio"), strings.HasSuffix(k, "secure_url"), strings.HasSuffix(k, "video"):
+			v, _ = strings.CutPrefix(v, "http://")
+			v, _ = strings.CutPrefix(v, "https://")
+			slog.Debug("setting ogtags allow for", "url", k)
+			if err := c.cache.Underlying.Set(ctx, "ogtags:allow:"+v, []byte(k), time.Hour); err != nil {
+				slog.Debug("can't set ogtag allow cache", "err", err)
+			}
+		}
+	}
+
 	return ogTags, nil
 }
 

internal/ogtags/cache_test.go

@@ -1,6 +1,7 @@
 package ogtags
 
 import (
+	"errors"
 	"net/http"
 	"net/http/httptest"
 	"net/url"
@@ -9,6 +10,7 @@ import (
 	"time"
 
 	"github.com/TecharoHQ/anubis/lib/policy/config"
+	"github.com/TecharoHQ/anubis/lib/store"
 	"github.com/TecharoHQ/anubis/lib/store/memory"
 )
 
@@ -166,8 +168,13 @@ func TestGetOGTags(t *testing.T) {
 		if !ok || initialValue != cachedValue {
 			t.Errorf("Cache does not line up: expected %s: %s, got: %s", key, initialValue, cachedValue)
 		}
-
 	}
+
+	t.Run("ensure image is cached as allow", func(t *testing.T) {
+		if _, err := cache.cache.Underlying.Get(t.Context(), "ogtags:allow:example.com/image.jpg"); errors.Is(err, store.ErrNotFound) {
+			t.Fatal("ogtags allow caching for example.com/image.jpg did not work")
+		}
+	})
 }
 
 // TestGetOGTagsWithHostConsideration tests the behavior of the cache with and without host consideration and for multiple hosts in a theoretical setup.