app/post_metadata: add a type cast check for OpenGraph images (#19877)

* app/post_metadata: add a type cast check for OpenGraph images

* change log level

Co-authored-by: Mattermod <mattermod@users.noreply.github.com>

app/post_metadata.go

@@ -295,7 +295,13 @@ func (a *App) getImagesForPost(post *model.Post, imageURLs []string, isNewPost b
 			imageURLs = append(imageURLs, a.getImagesInMessageAttachments(post)...)
 
 		case model.PostEmbedOpengraph:
-			for _, image := range embed.Data.(*opengraph.OpenGraph).Images {
+			openGraph, ok := embed.Data.(*opengraph.OpenGraph)
+			if !ok {
+				mlog.Warn("Could not read the image data: the data could not be casted to OpenGraph",
+					mlog.String("post_id", post.Id), mlog.String("data type", fmt.Sprintf("%t", embed.Data)))
+				continue
+			}
+			for _, image := range openGraph.Images {
 				var imageURL string
 				if image.SecureURL != "" {
 					imageURL = image.SecureURL

app/post_metadata_test.go

@@ -1222,6 +1222,29 @@ func TestGetImagesForPost(t *testing.T) {
 			},
 		})
 	})
+
+	t.Run("with an invalid OpenGraph image data", func(t *testing.T) {
+		th := Setup(t)
+		defer th.TearDown()
+
+		th.App.UpdateConfig(func(cfg *model.Config) {
+			*cfg.ServiceSettings.AllowedUntrustedInternalConnections = "127.0.0.1"
+		})
+
+		post := &model.Post{
+			Metadata: &model.PostMetadata{
+				Embeds: []*model.PostEmbed{
+					{
+						Type: model.PostEmbedOpengraph,
+						Data: map[string]interface{}{},
+					},
+				},
+			},
+		}
+
+		images := th.App.getImagesForPost(post, []string{}, false)
+		assert.Equal(t, images, map[string]*model.PostImage{})
+	})
 }
 
 func TestGetEmojiNamesForString(t *testing.T) {