Permission: refactor getPermissionFromPassword() to return std::optional

NEWS

 ver 0.23.1 (not yet released)
 * fix libfmt linker problems
+* fix broken password authentication
 
 ver 0.23 (2021/10/14)
 * protocol

src/Permission.cxx

@@ -161,15 +161,14 @@ GetPermissionsFromAddress(SocketAddress address) noexcept
 
 #endif
 
-int
-getPermissionFromPassword(const char *password, unsigned *permission) noexcept
+std::optional<unsigned>
+GetPermissionFromPassword(const char *password) noexcept
 {
 	auto i = permission_passwords.find(password);
 	if (i == permission_passwords.end())
-		return -1;
+		return std::nullopt;
 
-	*permission = i->second;
-	return 0;
+	return i->second;
 }
 
 unsigned

src/Permission.hxx

@@ -22,6 +22,8 @@
 
 #include "config.h"
 
+#include <optional>
+
 struct ConfigData;
 class SocketAddress;
 
@@ -32,9 +34,13 @@ static constexpr unsigned PERMISSION_CONTROL = 4;
 static constexpr unsigned PERMISSION_ADMIN = 8;
 static constexpr unsigned PERMISSION_PLAYER = 16;
 
+/**
+ * @return the permissions for the given password or std::nullopt if
+ * the password is not accepted
+ */
 [[gnu::pure]]
-int
-getPermissionFromPassword(const char *password, unsigned *permission) noexcept;
+std::optional<unsigned>
+GetPermissionFromPassword(const char *password) noexcept;
 
 [[gnu::const]]
 unsigned

src/command/ClientCommands.cxx

@@ -58,13 +58,13 @@ handle_binary_limit(Client &client, Request args,
 CommandResult
 handle_password(Client &client, Request args, Response &r)
 {
-	unsigned permission = 0;
-	if (getPermissionFromPassword(args.front(), &permission) < 0) {
+	const auto permission = GetPermissionFromPassword(args.front());
+	if (!permission) {
 		r.Error(ACK_ERROR_PASSWORD, "incorrect password");
 		return CommandResult::ERROR;
 	}
 
-	client.SetPermission(permission);
+	client.SetPermission(*permission);
 
 	return CommandResult::OK;
 }