1 files changed, 58 insertions, 0 deletions
diff --git a/backend/utils.go b/backend/utils.go
new file mode 100644
index 0000000..3628c80
--- /dev/null
+++ b/backend/utils.go
@@ -0,0 +1,58 @@
+/*
+ * Utility functions
+ *
+ * Copyright (C) 2024  Runxi Yu <https://runxiyu.org>
+ * SPDX-License-Identifier: AGPL-3.0-or-later
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+package main
+
+import (
+	"crypto/rand"
+	"encoding/base64"
+	"fmt"
+	"log"
+	"net/http"
+)
+
+/*
+ * Write a string to a http.ResponseWriter, setting the Content-Type and status
+ * code.
+ */
+func wstr(w http.ResponseWriter, code int, msg string) {
+	w.Header().Set("Content-Type", "text/plain; charset=utf-8")
+	w.WriteHeader(code)
+	_, err := w.Write([]byte(msg))
+	if err != nil {
+		log.Printf("Error wstr'ing to writer: %v", err)
+	}
+}
+
+/*
+ * Generate a random url-safe string.
+ * Note that the "sz" parameter specifies the number of bytes taken from the
+ * random source divided by three and does NOT represent the length of the
+ * encoded string. It's divided by three because we're using base64 and it's
+ * ideal to ensure that the entropy remains consistent throughout the string.
+ */
+func randomString(sz int) (string, error) {
+	r := make([]byte, 3*sz)
+	_, err := rand.Read(r)
+	if err != nil {
+		return "", fmt.Errorf("error generating random string: %w", err)
+	}
+	return base64.RawURLEncoding.EncodeToString(r), nil
+}