Feature: emoji editor (#2411)

* Custom emoji editor: implement backend

This reuses the logo upload code

* Implement emoji edit admin interface

Again reuse base64 logic from the logo upload

* Allow toggling between uploaded and default emojis

* Add route that always serves uploaded emojis

This is needed for the admin emoji interface,
as otherwise the emojis will 404 if custom emojis are disabled

* Fix linter warnings

* Remove custom/uploaded emoji logic

* Reset timer after emoji deletion

* Setup: copy built-in emojis to emoji directory

controllers/admin/emoji.go

@@ -0,0 +1,92 @@
+package admin
+
+import (
+	"encoding/json"
+	"fmt"
+	"net/http"
+	"os"
+	"path/filepath"
+
+	"github.com/owncast/owncast/config"
+	"github.com/owncast/owncast/controllers"
+	"github.com/owncast/owncast/utils"
+)
+
+// UploadCustomEmoji allows POSTing a new custom emoji to the server.
+func UploadCustomEmoji(w http.ResponseWriter, r *http.Request) {
+	if !requirePOST(w, r) {
+		return
+	}
+
+	type postEmoji struct {
+		Name string `json:"name"`
+		Data string `json:"data"`
+	}
+
+	emoji := new(postEmoji)
+
+	if err := json.NewDecoder(r.Body).Decode(emoji); err != nil {
+		controllers.WriteSimpleResponse(w, false, err.Error())
+		return
+	}
+
+	bytes, _, err := utils.DecodeBase64Image(emoji.Data)
+	if err != nil {
+		controllers.WriteSimpleResponse(w, false, err.Error())
+		return
+	}
+
+	// Prevent path traversal attacks
+	var emojiFileName = filepath.Base(emoji.Name)
+	var targetPath = filepath.Join(config.CustomEmojiPath, emojiFileName)
+
+	err = os.MkdirAll(config.CustomEmojiPath, 0700)
+	if err != nil {
+		controllers.WriteSimpleResponse(w, false, err.Error())
+		return
+	}
+
+	if utils.DoesFileExists(targetPath) {
+		controllers.WriteSimpleResponse(w, false, fmt.Sprintf("An emoji with the name %q already exists", emojiFileName))
+		return
+	}
+
+	if err = os.WriteFile(targetPath, bytes, 0o600); err != nil {
+		controllers.WriteSimpleResponse(w, false, err.Error())
+		return
+	}
+
+	controllers.WriteSimpleResponse(w, true, fmt.Sprintf("Emoji %q has been uploaded", emojiFileName))
+}
+
+// DeleteCustomEmoji deletes a custom emoji.
+func DeleteCustomEmoji(w http.ResponseWriter, r *http.Request) {
+	if !requirePOST(w, r) {
+		return
+	}
+
+	type deleteEmoji struct {
+		Name string `json:"name"`
+	}
+
+	emoji := new(deleteEmoji)
+
+	if err := json.NewDecoder(r.Body).Decode(emoji); err != nil {
+		controllers.WriteSimpleResponse(w, false, err.Error())
+		return
+	}
+
+	var emojiFileName = filepath.Base(emoji.Name)
+	var targetPath = filepath.Join(config.CustomEmojiPath, emojiFileName)
+
+	if err := os.Remove(targetPath); err != nil {
+		if os.IsNotExist(err) {
+			controllers.WriteSimpleResponse(w, false, fmt.Sprintf("Emoji %q doesn't exist", emojiFileName))
+		} else {
+			controllers.WriteSimpleResponse(w, false, err.Error())
+		}
+		return
+	}
+
+	controllers.WriteSimpleResponse(w, true, fmt.Sprintf("Emoji %q has been deleted", emojiFileName))
+}