finally.c

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/*
 *   This program 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: 884f2908c73e7c99788898b444f150e56fdad13c $
 *
 * @file unlang/finally.c
 * @brief Unlang "finally" keyword evaluation.  Used for running policy after a virtual server.
 *
 * @copyright 2025 Network RAIDUS SAS (legal@networkradius.com)
 */
 
RCSID("$Id: 884f2908c73e7c99788898b444f150e56fdad13c $")
 
#include <freeradius-devel/server/state.h>
#include <freeradius-devel/server/signal.h>
#include <freeradius-devel/server/pair.h>
#include <freeradius-devel/server/rcode.h>
#include <freeradius-devel/unlang/unlang_priv.h>
#include <freeradius-devel/unlang/action.h>
#include <freeradius-devel/unlang/finally.h>
#include <freeradius-devel/unlang/interpret.h>
#include <freeradius-devel/util/timer.h>
 
typedef struct {
        fr_time_delta_t                         min_time;       //!< minimum time to run the finally instruction.
        request_t                               *request;
        unlang_result_t                         result;         //!< Result of the finally instruction.  We discard this.
        rlm_rcode_t                             original_rcode; //!< The original request rcode when we entered.
        unlang_t                                *instruction;   //!< to run on timeout
} unlang_frame_state_finally_t;
 
static void unlang_timeout_handler(UNUSED fr_timer_list_t *tl, UNUSED fr_time_t now, void *ctx)
{
        unlang_frame_state_finally_t    *state = talloc_get_type_abort(ctx, unlang_frame_state_finally_t);
        request_t                       *request = talloc_get_type_abort(state->request, request_t);
 
        RDEBUG("Timeout reached, exiting finally section");
 
        /*
         *      Cancels all frames (other than other finally sections)
         *      and marks the request runnable again.
         */
        unlang_interpret_signal(request, FR_SIGNAL_CANCEL);
}
 
static unlang_action_t unlang_finally_resume(UNUSED unlang_result_t *p_result, request_t *request, unlang_stack_frame_t *frame)
{
        unlang_frame_state_finally_t    *state = talloc_get_type_abort(frame->state, unlang_frame_state_finally_t);
 
        /*
         *      Reset the request->rcode, so that any other
         *      finally sections have access to the original
         *      rcode like 'timeout'.
         */
        request->rcode = state->original_rcode;
 
        return UNLANG_ACTION_CALCULATE_RESULT;
}
 
static unlang_action_t unlang_finally(UNUSED unlang_result_t *p_result, request_t *request, unlang_stack_frame_t *frame)
{
        unlang_frame_state_finally_t    *state = talloc_get_type_abort(frame->state, unlang_frame_state_finally_t);
 
        state->original_rcode = request->rcode;
 
        /*
         *      Ensure the request has at least min_time to continue
         *      executing before we cancel it.
         */
        if (request->timeout && fr_time_delta_lt(state->min_time, fr_timer_remaining(request->timeout))) {
                if (unlikely(fr_timer_in(unlang_interpret_frame_talloc_ctx(request),
                             unlang_interpret_event_list(request)->tl, &request->timeout,
                             state->min_time, false, unlang_timeout_handler, state) < 0)) {
                fail:
                        unlang_interpret_signal(request, FR_SIGNAL_CANCEL); /* also stops the request and does cleanups */
                        return UNLANG_ACTION_FAIL;
                }
        }
 
        /*
         *      Finally should be transparent to allow the rcode from
         *      process module to propagate back up, if there are no
         *      modules called.
         */
        if (unlikely(unlang_interpret_push_instruction(&state->result, request, state->instruction,
                                                       FRAME_CONF(RLM_MODULE_NOOP, UNLANG_SUB_FRAME)) < 0)) {
                goto fail;
        }
 
        frame_repeat(frame, unlang_finally_resume);
 
        /*
         *      Set a timer to cancel the request.  If we don't do this
         *      then the request may never finish.
         */
        return UNLANG_ACTION_PUSHED_CHILD;
}
 
/** Push a finally instructtion on the stack, to be evaluated as the stack is unwound
 *
 * @param[in] request           to push timeout onto
 * @param[in] instruction       to run as we unwind
 * @param[in] min_time          max time to wait for the finally instruction to finish.
 *                              This only applies if the request timeout timer has already
 *                              fired, or has less than max_time to execute. i.e. this is
 *                              a guarantee of a minimum amount of time for the finally
 *                              instruction to run.
 * @param[in] top_frame         Set to UNLANG_TOP_FRAME if the interpreter should return.
 *                              Set to UNLANG_SUB_FRAME if the interprer should continue.
 *
 * @return
 *      - 0 on success.
 *      - -1 on failure.
 */
int unlang_finally_push_instruction(request_t *request, void *instruction, fr_time_delta_t min_time, bool top_frame)
{
        /** Static instruction for performing xlat evaluations
         *
         */
        static unlang_t finally_instruction = {
                .type = UNLANG_TYPE_FINALLY,
                .name = "finally",
                .debug_name = "finally",
                .actions = MOD_ACTIONS_FAIL_TIMEOUT_RETURN,
        };
 
        unlang_frame_state_finally_t    *state;
        unlang_stack_t                  *stack = request->stack;
        unlang_stack_frame_t            *frame;
 
        /*
         *      Push a new finally frame onto the stack
         *
         *      This frame is uncancellable, and will always
         *      execute before the request completes.
         *
         *      Its children are very much cancellable though
         *      and will be cancelled if min_time or the request
         *      timer expires.
         */
        if (unlang_interpret_push(NULL, request, &finally_instruction,
                                  FRAME_CONF(RLM_MODULE_NOT_SET, top_frame), UNLANG_NEXT_STOP) < 0) return -1;
        frame = &stack->frame[stack->depth];
 
        /*
         *      Allocate its state
         */
        MEM(frame->state = state = talloc_zero(stack, unlang_frame_state_finally_t));
        state->instruction = instruction;
        state->request = request;
        state->min_time = min_time;
 
        frame_repeat(frame, unlang_finally);    /* execute immediately... or when unwinding */
 
        return 0;
 
}
 
void unlang_finally_init(void)
{
        unlang_register(&(unlang_op_t){
                        .name = "finally",
                        .type = UNLANG_TYPE_FINALLY,
 
                        .interpret = unlang_finally,
 
                        /*
                         *      No debug braces, the thing
                         *      that's pushed in unlang
                         *      finally should have braces
                         */
                        .flag = UNLANG_OP_FLAG_NO_FORCE_UNWIND | UNLANG_OP_FLAG_RETURN_POINT | UNLANG_OP_FLAG_INTERNAL,
 
                        .frame_state_size = sizeof(unlang_frame_state_finally_t),
                        .frame_state_type = "unlang_frame_state_finally_t",
                });
}