Mono repo -> Master (#22553)

Combines the following repositories into one:

https://github.com/mattermost/mattermost-server
https://github.com/mattermost/mattermost-webapp
https://github.com/mattermost/focalboard
https://github.com/mattermost/mattermost-plugin-playbooks

server/channels/app/image.go

@@ -0,0 +1,32 @@
+// Copyright (c) 2015-present Mattermost, Inc. All Rights Reserved.
+// See LICENSE.txt for license information.
+
+package app
+
+import (
+	"fmt"
+	"io"
+
+	"github.com/mattermost/mattermost-server/v6/server/channels/app/imaging"
+)
+
+func checkImageResolutionLimit(w, h int, maxRes int64) error {
+	// This casting is done to prevent overflow on 32 bit systems (not needed
+	// in 64 bits systems because images can't have more than 32 bits height or
+	// width)
+	imageRes := int64(w) * int64(h)
+	if imageRes > maxRes {
+		return fmt.Errorf("image resolution is too high: %d, max allowed is %d", imageRes, maxRes)
+	}
+
+	return nil
+}
+
+func checkImageLimits(imageData io.Reader, maxRes int64) error {
+	w, h, err := imaging.GetDimensions(imageData)
+	if err != nil {
+		return fmt.Errorf("failed to get image dimensions: %w", err)
+	}
+
+	return checkImageResolutionLimit(w, h, maxRes)
+}