rlm_delay.c

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/*
 *   This program is is free software; you can redistribute it and/or modify
 *   it under the terms of the GNU General Public License as published by
 *   the Free Software Foundation; either version 2 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 General Public License for more details.
 *
 *   You should have received a copy of the GNU General Public License
 *   along with this program; if not, write to the Free Software
 *   Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301, USA
 */
 
/**
 * $Id: 679be93d1e158e2a0f648301a2c81e938e361deb $
 * @file rlm_delay.c
 * @brief Add an artificial delay to requests.
 *
 * @copyright 2016 The FreeRADIUS server project
 * @copyright 2016 Arran Cudbard-Bell (a.cudbardb@freeradius.org)
 */
RCSID("$Id: 679be93d1e158e2a0f648301a2c81e938e361deb $")
 
#include <freeradius-devel/server/base.h>
#include <freeradius-devel/server/module_rlm.h>
#include <freeradius-devel/util/debug.h>
#include <freeradius-devel/server/map_proc.h>
#include <freeradius-devel/util/time.h>
#include <freeradius-devel/unlang/xlat_func.h>
 
typedef struct {
        tmpl_t          *delay;                 //!< How long we delay for.
        bool            relative;               //!< Whether the delay is relative to the start of request processing.
        bool            force_reschedule;       //!< Whether we should force rescheduling of the request.
} rlm_delay_t;
 
/*
 *      A mapping of configuration file names to internal variables.
 */
static const conf_parser_t module_config[] = {
        { FR_CONF_OFFSET_HINT_TYPE("delay", FR_TYPE_TIME_DELTA, rlm_delay_t, delay) },
        { FR_CONF_OFFSET("relative", rlm_delay_t, relative), .dflt = "no" },
        { FR_CONF_OFFSET("force_reschedule", rlm_delay_t, force_reschedule), .dflt = "no" },
        CONF_PARSER_TERMINATOR
};
 
typedef struct {
        fr_retry_config_t       retry_cfg;
        fr_time_t               when;
} rlm_delay_retry_t;
 
/** Called when the timeout has expired
 *
 * Marks the request as resumable, and prints the delayed delay time.
 */
static void _delay_done(module_ctx_t const *mctx, request_t *request, fr_retry_t const *retry)
{
        rlm_delay_retry_t *yielded = talloc_get_type_abort(mctx->rctx, rlm_delay_retry_t);
 
        RDEBUG2("Delay done");
 
        /*
         *      timeout should never be *before* the scheduled time,
         *      if it is, something is very broken.
         */
        if (!fr_cond_assert(fr_time_gteq(retry->updated, yielded->when))) REDEBUG("Unexpected resume time");
}
 
static void _xlat_delay_done(xlat_ctx_t const *xctx, request_t *request, fr_time_t fired)
{
        fr_time_t *yielded = talloc_get_type_abort(xctx->rctx, fr_time_t);
 
        RDEBUG2("Delay done");
 
        /*
         *      timeout should never be *before* the scheduled time,
         *      if it is, something is very broken.
         */
        if (!fr_cond_assert(fr_time_gt(fired, *yielded))) REDEBUG("Unexpected resume time");
 
        unlang_interpret_mark_runnable(request);
}
 
static int delay_add(request_t *request, fr_time_t *resume_at, fr_time_t now,
                     fr_time_delta_t delay, bool force_reschedule, bool relative)
{
        /*
         *      Delay is zero (and reschedule is not forced)
         */
        if (!force_reschedule && !fr_time_delta_ispos(delay)) return 1;
 
        /*
         *      Process the delay relative to the start of packet processing
         */
        if (relative) {
                *resume_at = fr_time_add(request->packet->timestamp, delay);
        } else {
                *resume_at = fr_time_add(now, delay);
        }
 
        /*
         *      If resume_at is in the past (and reschedule is not forced), just return noop
         */
        if (!force_reschedule && fr_time_lteq(*resume_at, now)) return 1;
 
        if (fr_time_gt(*resume_at, now)) {
                RDEBUG2("Delaying request by ~%pVs", fr_box_time_delta(fr_time_sub(*resume_at, now)));
        } else {
                RDEBUG2("Rescheduling request");
        }
 
        return 0;
}
 
/** Called resume_at the delay is complete, and we're running from the interpreter
 *
 */
static unlang_action_t mod_delay_return(rlm_rcode_t *p_result, module_ctx_t const *mctx, request_t *request)
{
        rlm_delay_retry_t *yielded = talloc_get_type_abort(mctx->rctx, rlm_delay_retry_t);
 
        /*
         *      Print how long the delay *really* was.
         */
        RDEBUG3("Request delayed by %pV", fr_box_time_delta(fr_time_sub(fr_time(), yielded->when)));
        talloc_free(yielded);
 
        RETURN_MODULE_OK;
}
 
static unlang_action_t CC_HINT(nonnull) mod_delay(rlm_rcode_t *p_result, module_ctx_t const *mctx, request_t *request)
{
        rlm_delay_t const       *inst = talloc_get_type_abort_const(mctx->mi->data, rlm_delay_t);
        fr_time_delta_t         delay;
        rlm_delay_retry_t       *yielded;
        fr_time_t               resume_at;
 
        if (inst->delay) {
                if (tmpl_aexpand_type(request, &delay, FR_TYPE_TIME_DELTA,
                                      request, inst->delay) < 0) {
                        RPEDEBUG("Failed parsing %s as delay time", inst->delay->name);
                        RETURN_MODULE_FAIL;
                }
 
                /*
                 *      Cap delays.  So that no matter what crazy
                 *      thing the admin does, it doesn't cause an
                 *      issue.
                 */
                if (fr_time_delta_cmp(delay, fr_time_delta_from_sec(0)) < 0) {
                        RWDEBUG("Delay is too small.  Limiting to 0s");
                        delay = fr_time_delta_wrap(0);
 
                } else if (fr_time_delta_cmp(delay, fr_time_delta_from_sec(30)) > 0) {
                        RWDEBUG("Delay is too large.  Limiting to 30s");
                        delay = fr_time_delta_from_sec(30);
                }
 
        } else {
                delay = fr_time_delta_wrap(0);
        }
 
        /*
         *      Record the time that we yielded the request
         */
        MEM(yielded = talloc(unlang_interpret_frame_talloc_ctx(request), rlm_delay_retry_t));
        yielded->when = fr_time();
 
        /*
         *      Setup the delay for this request
         */
        if (delay_add(request, &resume_at, yielded->when, delay,
                      inst->force_reschedule, inst->relative) != 0) {
                RETURN_MODULE_NOOP;
        }
 
        RDEBUG3("Current time %pVs, resume time %pVs",
                fr_box_time(yielded->when), fr_box_time(resume_at));
 
        /*
         *
         */
        yielded->retry_cfg = (fr_retry_config_t) {
                .mrd = delay,
                .mrc = 1,
        };
 
        return unlang_module_yield_to_retry(request, mod_delay_return, _delay_done, NULL, 0,
                                            yielded, &yielded->retry_cfg);
}
 
static xlat_action_t xlat_delay_resume(TALLOC_CTX *ctx, fr_dcursor_t *out,
                                       xlat_ctx_t const *xctx,
                                       request_t *request, UNUSED fr_value_box_list_t *in)
{
        fr_time_t       *yielded_at = talloc_get_type_abort(xctx->rctx, fr_time_t);
        fr_time_delta_t delayed;
        fr_value_box_t  *vb;
 
        delayed = fr_time_sub(fr_time(), *yielded_at);
        talloc_free(yielded_at);
 
        MEM(vb = fr_value_box_alloc(ctx, FR_TYPE_TIME_DELTA, NULL));
        vb->vb_time_delta = delayed;
 
        RDEBUG3("Request delayed by %pVs", vb);
 
        fr_dcursor_insert(out, vb);
 
        return XLAT_ACTION_DONE;
}
 
static void xlat_delay_cancel(UNUSED xlat_ctx_t const *xctx, request_t *request, UNUSED fr_signal_t action)
{
        RDEBUG2("Cancelling delay");
}
 
static xlat_arg_parser_t const xlat_delay_args[] = {
        { .single = true, .type = FR_TYPE_TIME_DELTA },
        XLAT_ARG_PARSER_TERMINATOR
};
 
/** Xlat to delay the request
 *
 * Example (delay 2 seconds):
@verbatim
%delay(2)
@endverbatim
 *
 * @ingroup xlat_functions
 */
static xlat_action_t xlat_delay(UNUSED TALLOC_CTX *ctx, UNUSED fr_dcursor_t *out,
                                xlat_ctx_t const *xctx,
                                request_t *request, fr_value_box_list_t *in)
{
        rlm_delay_t const       *inst = talloc_get_type_abort(xctx->mctx->mi->data, rlm_delay_t);
        fr_time_t               resume_at, *yielded_at;
        fr_value_box_t          *delay = fr_value_box_list_head(in);
 
        /*
         *      Record the time that we yielded the request
         */
        MEM(yielded_at = talloc(request, fr_time_t));
        *yielded_at = fr_time();
 
        /*
         *      If there's no input delay, just yield and
         *      immediately re-enqueue the request.
         *      This is very useful for testing.
         */
        if (!delay) {
                if (!fr_cond_assert(delay_add(request, &resume_at, *yielded_at, fr_time_delta_wrap(0), true, true) == 0)) {
                        return XLAT_ACTION_FAIL;
                }
                goto yield;
        }
 
        if (delay_add(request, &resume_at, *yielded_at, delay->vb_time_delta,
                      inst->force_reschedule, inst->relative) != 0) {
                RDEBUG2("Not adding delay");
                talloc_free(yielded_at);
                return XLAT_ACTION_DONE;
        }
 
yield:
        RDEBUG3("Current time %pVs, resume time %pVs", fr_box_time(*yielded_at), fr_box_time(resume_at));
 
        if (unlang_xlat_timeout_add(request, _xlat_delay_done, yielded_at, resume_at) < 0) {
                RPEDEBUG("Adding event failed");
                return XLAT_ACTION_FAIL;
        }
 
        return unlang_xlat_yield(request, xlat_delay_resume, xlat_delay_cancel, ~FR_SIGNAL_CANCEL, yielded_at);
}
 
static int mod_bootstrap(module_inst_ctx_t const *mctx)
{
        xlat_t          *xlat;
 
        xlat = module_rlm_xlat_register(mctx->mi->boot, mctx, NULL, xlat_delay, FR_TYPE_TIME_DELTA);
        xlat_func_args_set(xlat, xlat_delay_args);
        return 0;
}
 
extern module_rlm_t rlm_delay;
module_rlm_t rlm_delay = {
        .common = {
                .magic          = MODULE_MAGIC_INIT,
                .name           = "delay",
                .flags          = 0,
                .inst_size      = sizeof(rlm_delay_t),
                .config         = module_config,
                .bootstrap      = mod_bootstrap
        },
        .method_group = {
                .bindings = (module_method_binding_t[]){
                        { .section = SECTION_NAME(CF_IDENT_ANY, CF_IDENT_ANY), .method = mod_delay },
                        MODULE_BINDING_TERMINATOR
                }
        }
};