Maint: move OpenVPN configurator to openvpn/config

internal/openvpn/config/auth.go

@@ -0,0 +1,69 @@
+package config
+
+import (
+	"io"
+	"os"
+	"strings"
+)
+
+type AuthWriter interface {
+	WriteAuthFile(user, password string) error
+}
+
+// WriteAuthFile writes the OpenVPN auth file to disk with the right permissions.
+func (c *configurator) WriteAuthFile(user, password string) error {
+	file, err := os.Open(c.authFilePath)
+
+	if err != nil && !os.IsNotExist(err) {
+		return err
+	}
+
+	if os.IsNotExist(err) {
+		file, err = os.OpenFile(c.authFilePath, os.O_WRONLY|os.O_CREATE, 0400)
+		if err != nil {
+			return err
+		}
+		_, err = file.WriteString(user + "\n" + password)
+		if err != nil {
+			_ = file.Close()
+			return err
+		}
+		err = file.Chown(c.puid, c.pgid)
+		if err != nil {
+			_ = file.Close()
+			return err
+		}
+		return file.Close()
+	}
+
+	data, err := io.ReadAll(file)
+	if err != nil {
+		_ = file.Close()
+		return err
+	}
+	if err := file.Close(); err != nil {
+		return err
+	}
+
+	lines := strings.Split(string(data), "\n")
+	if len(lines) > 1 && lines[0] == user && lines[1] == password {
+		return nil
+	}
+
+	c.logger.Info("username and password changed in " + c.authFilePath)
+	file, err = os.OpenFile(c.authFilePath, os.O_TRUNC|os.O_WRONLY, 0400)
+	if err != nil {
+		return err
+	}
+	_, err = file.WriteString(user + "\n" + password)
+	if err != nil {
+		_ = file.Close()
+		return err
+	}
+	err = file.Chown(c.puid, c.pgid)
+	if err != nil {
+		_ = file.Close()
+		return err
+	}
+	return file.Close()
+}