/* -------------------------------------------------------------------------
 *
 * auth_delay.c
 *
 * Copyright (c) 2010-2025, PostgreSQL Global Development Group
 *
 * IDENTIFICATION
 *  contrib/auth_delay/auth_delay.c
 *
 * -------------------------------------------------------------------------
 */
#include "postgres.h"

#include <limits.h>

#include "libpq/auth.h"
#include "utils/guc.h"

PG_MODULE_MAGIC_EXT(
     .name = "auth_delay",
     .version = PG_VERSION
);

/* GUC Variables */
static int auth_delay_milliseconds = 0;

/* Original Hook */
static ClientAuthentication_hook_type original_client_auth_hook = NULL;

/*
 * Check authentication
 */
static void
auth_delay_checks(Port *port, int status)
{
 /*
  * Any other plugins which use ClientAuthentication_hook.
 */
 if (original_client_auth_hook)
  original_client_auth_hook(port, status);

 /*
  * Inject a short delay if authentication failed.
 */
 if (status != STATUS_OK)
 {
  pg_usleep(1000L * auth_delay_milliseconds);
 }
}

/*
 * Module Load Callback
 */
void
_PG_init(void)
{
 /* Define custom GUC variables */
 DefineCustomIntVariable("auth_delay.milliseconds",
       "Milliseconds to delay before reporting authentication failure",
       NULL,
       &auth_delay_milliseconds,
       0,
       0, INT_MAX / 1000,
       PGC_SIGHUP,
       GUC_UNIT_MS,
       NULL,
       NULL,
       NULL);

 MarkGUCPrefixReserved("auth_delay");

 /* Install Hooks */
 original_client_auth_hook = ClientAuthentication_hook;
 ClientAuthentication_hook = auth_delay_checks;
}