module.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: 03d39d5bfecab0f27bf4a629575796e093e1f0f8 $
 *
 * @file unlang/module.c
 * @brief Defines functions for calling modules asynchronously
 *
 * @copyright 2018 The FreeRADIUS server project
 * @copyright 2018 Arran Cudbard-Bell (a.cudbardb@freeradius.org)
 */
 
RCSID("$Id: 03d39d5bfecab0f27bf4a629575796e093e1f0f8 $")
 
#include <freeradius-devel/server/modpriv.h>
#include <freeradius-devel/server/request_data.h>
#include <freeradius-devel/server/rcode.h>
#include <freeradius-devel/unlang/call_env.h>
 
#include "module_priv.h"
 
#include "tmpl.h"
 
static unlang_action_t unlang_module_resume(rlm_rcode_t *p_result, request_t *request, unlang_stack_frame_t *frame);
static void unlang_module_event_retry_handler(UNUSED fr_event_list_t *el, fr_time_t now, void *ctx);
 
/** Push a module or submodule onto the stack for evaluation
 *
 * @param[out] p_result         Where to write the result of calling the module.
 * @param[in] request           The current request.
 * @param[in] mi                Instance of the module to call.
 * @param[in] method            to call.
 * @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_module_push(rlm_rcode_t *p_result, request_t *request,
                       module_instance_t *mi, module_method_t method, bool top_frame)
{
        unlang_stack_t                  *stack = request->stack;
        unlang_stack_frame_t            *frame;
        unlang_frame_state_module_t     *state;
        unlang_module_t                 *mc;
 
        /*
         *      We need to have a unlang_module_t to push on the
         *      stack.  The only sane way to do it is to attach it to
         *      the frame state.
         */
        MEM(mc = talloc(stack, unlang_module_t));       /* Still gets allocated from the stack pool */
        *mc = (unlang_module_t){
                .self = {
                        .type = UNLANG_TYPE_MODULE,
                        .name = mi->name,
                        .debug_name = mi->name,
                        .actions = {
                                .actions = {
                                        [RLM_MODULE_REJECT]     = 0,
                                        [RLM_MODULE_FAIL]       = MOD_ACTION_RETURN,    /* Exit out of nested levels */
                                        [RLM_MODULE_OK]         = 0,
                                        [RLM_MODULE_HANDLED]    = 0,
                                        [RLM_MODULE_INVALID]    = 0,
                                        [RLM_MODULE_DISALLOW]   = 0,
                                        [RLM_MODULE_NOTFOUND]   = 0,
                                        [RLM_MODULE_NOOP]       = 0,
                                        [RLM_MODULE_UPDATED]    = 0
                                },
                                .retry = RETRY_INIT,
                        },
                },
                .mmc = {
                        .mi = mi,
                        .mmb = {
                                .method = method
                        }
                }
        };
 
        /*
         *      Push a new module frame onto the stack
         */
        if (unlang_interpret_push(request, unlang_module_to_generic(mc),
                                  RLM_MODULE_NOT_SET, UNLANG_NEXT_STOP, top_frame) < 0) {
                return -1;
        }
 
        frame = &stack->frame[stack->depth];
        state = frame->state;
        *state = (unlang_frame_state_module_t){
                .p_result = p_result,
                .thread = module_thread(mi)
        };
 
        /*
         *      Bind the temporary unlang_module_t to the frame state.
         *
         *      There aren't _that_ many children in the stack context.
         *      so we should be ok.
         *
         *      Hopefully in future versions of talloc the O(n) problem
         *      will be fixed for stealing.
         */
        talloc_steal(state, mc);
 
        return 0;
}
 
/** Change the resume function of a module.
 *
 * @param[in] request           The current request.
 * @param[in] resume            function to call when the XLAT expansion is complete.
 * @return
 *      - <0 on error
 *      - 0 on success
 */
int unlang_module_set_resume(request_t *request, module_method_t resume)
{
        unlang_stack_t                  *stack = request->stack;
        unlang_stack_frame_t            *frame = &stack->frame[stack->depth];
        unlang_frame_state_module_t     *state;
 
        /*
         *      Can't resume if it isn't yielded.
         */
        if (!is_yielded(frame)) return -1;
 
        /*
         *      It must be yielded in a module.
         */
        if (frame->instruction->type != UNLANG_TYPE_MODULE) return -1;
 
        state = talloc_get_type_abort(frame->state, unlang_frame_state_module_t);
        state->resume = resume;
 
        return 0;
}
 
/** Push a pre-compiled xlat and resumption state onto the stack for evaluation
 *
 * In order to use the async unlang processor the calling module needs to establish
 * a resumption point, as the call to an xlat function may require yielding control
 * back to the interpreter.
 *
 * To simplify the calling conventions, this function is provided to first push a
 * resumption stack frame for the module, and then push an xlat stack frame.
 *
 * After pushing those frames the function updates the stack pointer to jump over
 * the resumption frame and execute the xlat interpreter.
 *
 * When the xlat interpreter finishes, and pops the xlat frame, the unlang interpreter
 * will then call the module resumption frame, allowing the module to continue execution.
 *
 * @param[in] ctx               To allocate talloc value boxes and values in.
 * @param[out] p_success        Whether xlat evaluation was successful.
 * @param[out] out              Where to write the result of the expansion.
 * @param[in] request           The current request.
 * @param[in] exp               XLAT expansion to evaluate.
 * @param[in] resume            function to call when the XLAT expansion is complete.
 * @param[in] signal            function to call if a signal is received.
 * @param[in] sigmask           Signals to block.
 * @param[in] rctx              to pass to the resume() and signal() callbacks.
 * @return
 *      - UNLANG_ACTION_PUSHED_CHILD
 */
unlang_action_t unlang_module_yield_to_xlat(TALLOC_CTX *ctx, bool *p_success, fr_value_box_list_t *out,
                                            request_t *request, xlat_exp_head_t const *exp,
                                            module_method_t resume,
                                            unlang_module_signal_t signal, fr_signal_t sigmask, void *rctx)
{
        /*
         *      Push the resumption point BEFORE pushing the xlat onto
         *      the parents stack.
         */
        (void) unlang_module_yield(request, resume, signal, sigmask, rctx);
 
        /*
         *      Push the xlat function
         */
        if (unlang_xlat_push(ctx, p_success, out, request, exp, false) < 0) return UNLANG_ACTION_STOP_PROCESSING;
 
        return UNLANG_ACTION_PUSHED_CHILD;
}
 
/** Push a pre-compiled tmpl and resumption state onto the stack for evaluation
 *
 * In order to use the async unlang processor the calling module needs to establish
 * a resumption point, as the call to an xlat function may require yielding control
 * back to the interpreter.
 *
 * To simplify the calling conventions, this function is provided to first push a
 * resumption stack frame for the module, and then push a tmpl stack frame.
 *
 * After pushing those frames the function updates the stack pointer to jump over
 * the resumption frame and execute the tmpl expansion.
 *
 * When the tmpl interpreter finishes, and pops the tmpl frame, the unlang interpreter
 * will then call the module resumption frame, allowing the module to continue execution.
 *
 * @param[in] ctx               To allocate talloc value boxes and values in.
 * @param[out] out              Where to write the result of the expansion.
 * @param[in] request           The current request.
 * @param[in] vpt               the tmpl to expand
 * @param[in] args              Arguments which control how to evaluate the various
 *                              types of xlats.
 * @param[in] resume            function to call when the XLAT expansion is complete.
 * @param[in] signal            function to call if a signal is received.
 * @param[in] sigmask           Signals to block.
 * @param[in] rctx              to pass to the resume() and signal() callbacks.
 * @return
 *      - UNLANG_ACTION_PUSHED_CHILD
 */
unlang_action_t unlang_module_yield_to_tmpl(TALLOC_CTX *ctx, fr_value_box_list_t *out,
                                            request_t *request, tmpl_t const *vpt,
                                            unlang_tmpl_args_t *args,
                                            module_method_t resume,
                                            unlang_module_signal_t signal, fr_signal_t sigmask, void *rctx)
{
        /*
         *      Push the resumption point BEFORE pushing the xlat onto
         *      the parents stack.
         */
        (void) unlang_module_yield(request, resume, signal, sigmask, rctx);
 
        /*
         *      Push the xlat function
         */
        if (unlang_tmpl_push(ctx, out, request, vpt, args) < 0) return UNLANG_ACTION_FAIL;
 
        return UNLANG_ACTION_PUSHED_CHILD;
}
 
unlang_action_t unlang_module_yield_to_section(rlm_rcode_t *p_result,
                                               request_t *request, CONF_SECTION *subcs,
                                               rlm_rcode_t default_rcode,
                                               module_method_t resume,
                                               unlang_module_signal_t signal, fr_signal_t sigmask, void *rctx)
{
        if (!subcs) {
                unlang_stack_t                  *stack = request->stack;
                unlang_stack_frame_t            *frame = &stack->frame[stack->depth];
                unlang_module_t                 *m;
                unlang_frame_state_module_t     *state;
 
                fr_assert(frame->instruction->type == UNLANG_TYPE_MODULE);
                m = unlang_generic_to_module(frame->instruction);
 
                /*
                 *      Be transparent to the resume function.
                 *      frame->result will be overwritten
                 *      anyway when we return.
                 */
                stack->result = frame->result = default_rcode;
                state = talloc_get_type_abort(frame->state, unlang_frame_state_module_t);
 
                return resume(p_result,
                              MODULE_CTX(m->mmc.mi, module_thread(m->mmc.mi)->data,
                                         state->env_data, rctx),
                              request);
        }
 
        /*
         *      Push the resumption point BEFORE adding the subsection
         *      to the parents stack.
         */
        (void) unlang_module_yield(request, resume, signal, sigmask, rctx);
 
        if (unlang_interpret_push_section(request, subcs,
                                          default_rcode, UNLANG_SUB_FRAME) < 0) return UNLANG_ACTION_STOP_PROCESSING;
 
        return UNLANG_ACTION_PUSHED_CHILD;
}
 
/** Run the retry handler.  Called from an async signal handler.
 *
 */
void unlang_module_retry_now(module_ctx_t const *mctx, request_t *request)
{
        unlang_stack_t                  *stack = request->stack;
        unlang_stack_frame_t            *frame = &stack->frame[stack->depth];
        unlang_frame_state_module_t     *state = talloc_get_type_abort(frame->state, unlang_frame_state_module_t);
 
        if (!state->retry_cb) return;
 
        /*
         *      Assert that we have the right things.  Note that this function should only be called when the
         *      retry is being used as an expiry time, i.e. mrc==1.  If the module has its own retry handlers,
         *      then this function must not be called.
         */
        fr_assert(state->retry.config != NULL);
        fr_assert(state->retry.config->mrc == 1);
        fr_assert(state->rctx == mctx->rctx);
        fr_assert(state->request == request);
 
        /*
         *      Update the time as to when the retry is being called.  This is the main purpose of the
         *      function.
         */
        state->retry.updated = fr_time();
 
        state->retry_cb(mctx, request, &state->retry);
 
}
 
/** Cancel the retry timer on resume
 *
 */
static unlang_action_t unlang_module_retry_resume(rlm_rcode_t *p_result, module_ctx_t const *mctx, request_t *request)
{
        unlang_stack_t                  *stack = request->stack;
        unlang_stack_frame_t            *frame = &stack->frame[stack->depth];
        unlang_frame_state_module_t     *state = talloc_get_type_abort(frame->state, unlang_frame_state_module_t);
 
        /*
         *      Cancel the timers, and clean up any associated retry configuration.
         */
        talloc_const_free(state->ev);
        state->ev = NULL;
        state->retry_cb = NULL;
        state->retry.config = NULL;
 
        return state->retry_resume(p_result, mctx, request);
}
 
/** Yield a request back to the interpreter, with retries
 *
 * This passes control of the request back to the unlang interpreter, setting
 * callbacks to execute when the request is 'signalled' asynchronously, or when
 * the retry timer hits.
 *
 * @note The module function which calls #unlang_module_yield_to_retry should return control
 *      of the C stack to the unlang interpreter immediately after calling #unlang_module_yield_to_retry.
 *      A common pattern is to use ``return unlang_module_yield_to_retry(...)``.
 *
 * @param[in] request           The current request.
 * @param[in] resume            Called on unlang_interpret_mark_runnable().
 * @param[in] retry             Called on when a retry timer hits
 * @param[in] signal            Called on unlang_action().
 * @param[in] sigmask           Set of signals to block.
 * @param[in] rctx              to pass to the callbacks.
 * @param[in] retry_cfg         to set up the retries
 * @return
 *      - UNLANG_ACTION_YIELD on success
 *      - UNLANG_ACTION_FAIL on failure
 */
unlang_action_t unlang_module_yield_to_retry(request_t *request, module_method_t resume, unlang_module_retry_t retry,
                                             unlang_module_signal_t signal, fr_signal_t sigmask, void *rctx,
                                             fr_retry_config_t const *retry_cfg)
{
        unlang_stack_t                  *stack = request->stack;
        unlang_stack_frame_t            *frame = &stack->frame[stack->depth];
        unlang_module_t                 *m;
        unlang_frame_state_module_t     *state = talloc_get_type_abort(frame->state, unlang_frame_state_module_t);
 
        fr_assert(stack->depth > 0);
        fr_assert(frame->instruction->type == UNLANG_TYPE_MODULE);
        m = unlang_generic_to_module(frame->instruction);
 
        fr_assert(!state->retry_cb);
 
        state->retry_cb = retry;
        state->retry_resume = resume;           // so that we can cancel the retry timer
        state->rctx = rctx;
 
        state->request = request;
        state->mi = m->mmc.mi;
 
        /*
         *      Allow unlang statements to override the module configuration.  i.e. if we already have a
         *      timer from unlang, then just use that.
         */
        if (!state->retry.config) {
                fr_retry_init(&state->retry, fr_time(), retry_cfg);
 
                if (fr_event_timer_at(state, unlang_interpret_event_list(request), &state->ev,
                                      state->retry.next, unlang_module_event_retry_handler, request) < 0) {
                        RPEDEBUG("Failed inserting event");
                        return UNLANG_ACTION_FAIL;
                }
        }
 
        return unlang_module_yield(request, unlang_module_retry_resume, signal, sigmask, rctx);
}
 
 
/** Yield a request back to the interpreter from within a module
 *
 * This passes control of the request back to the unlang interpreter, setting
 * callbacks to execute when the request is 'signalled' asynchronously, or whatever
 * timer or I/O event the module was waiting for occurs.
 *
 * @note The module function which calls #unlang_module_yield should return control
 *      of the C stack to the unlang interpreter immediately after calling #unlang_module_yield.
 *      A common pattern is to use ``return unlang_module_yield(...)``.
 *
 * @param[in] request           The current request.
 * @param[in] resume            Called on unlang_interpret_mark_runnable().
 * @param[in] signal            Called on unlang_action().
 * @param[in] sigmask           Set of signals to block.
 * @param[in] rctx              to pass to the callbacks.
 * @return
 *      - UNLANG_ACTION_YIELD.
 */
unlang_action_t unlang_module_yield(request_t *request,
                                    module_method_t resume, unlang_module_signal_t signal, fr_signal_t sigmask, void *rctx)
{
        unlang_stack_t                  *stack = request->stack;
        unlang_stack_frame_t            *frame = &stack->frame[stack->depth];
        unlang_frame_state_module_t     *state = talloc_get_type_abort(frame->state, unlang_frame_state_module_t);
 
        REQUEST_VERIFY(request);        /* Check the yielded request is sane */
 
        state->rctx = rctx;
        state->resume = resume;
 
#ifndef NDEBUG
        /*
         *      We can't do asynchronous signals if the module is not thread safe.
         *
         *      Right now, none of the modules marked THREAD_UNSAFE call yield, or set signal callbacks.
         *      Which means that this code doesn't affect anything.
         *
         *      At some point if we do have modules which take signals and which are not thread safe, then
         *      those modules have to ensure that their signal handlers do any locking necessary.
         */
        if (signal) {
                unlang_module_t *m;
 
                m = unlang_generic_to_module(frame->instruction);
                fr_assert(m);
 
                fr_assert((m->mmc.mi->exported->flags & MODULE_TYPE_THREAD_UNSAFE) == 0);
        }
#endif
 
        state->signal = signal;
        state->sigmask = sigmask;
 
        /*
         *      We set the repeatable flag here,
         *      so that the resume function is always
         *      called going back up the stack.
         */
        frame_repeat(frame, unlang_module_resume);
 
        return UNLANG_ACTION_YIELD;
}
 
/*
 *      Lock the mutex for the module
 */
static inline CC_HINT(always_inline) void safe_lock(module_instance_t *mi)
{
        if ((mi->exported->flags & MODULE_TYPE_THREAD_UNSAFE) != 0) pthread_mutex_lock(&mi->mutex);
}
 
/*
 *      Unlock the mutex for the module
 */
static inline CC_HINT(always_inline) void safe_unlock(module_instance_t *mi)
{
        if ((mi->exported->flags & MODULE_TYPE_THREAD_UNSAFE) != 0) pthread_mutex_unlock(&mi->mutex);
}
 
/** Send a signal (usually stop) to a request
 *
 * This is typically called via an "async" action, i.e. an action
 * outside of the normal processing of the request.
 *
 * If there is no #unlang_module_signal_t callback defined, the action is ignored.
 *
 * @param[in] request           The current request.
 * @param[in] frame             current stack frame.
 * @param[in] action            to signal.
 */
static void unlang_module_signal(request_t *request, unlang_stack_frame_t *frame, fr_signal_t action)
{
        unlang_frame_state_module_t     *state = talloc_get_type_abort(frame->state, unlang_frame_state_module_t);
        unlang_module_t                 *m = unlang_generic_to_module(frame->instruction);
        char const                      *caller;
 
        if (!state->signal) return;
 
        /*
         *      Async calls can't push anything onto the unlang stack, so we just use a local "caller" here.
         */
        caller = request->module;
        request->module = m->mmc.mi->name;
 
        /*
         *      Call the signal routines.  Note that signals are
         *      explicitely asynchronous, even if the module has
         *      declared itself to be MODULE_TYPE_THREAD_UNSAFE.
         */
        if (!(action & state->sigmask)) state->signal(MODULE_CTX(m->mmc.mi, state->thread->data, state->env_data, state->rctx), request, action);
 
        if (action == FR_SIGNAL_CANCEL) {
                /*
                 *      One fewer caller for this module.  Since this module
                 *      has been cancelled, decrement the active callers and
                 *      ignore any future signals.
                 */
                state->thread->active_callers--;
                state->signal = NULL;
        }
 
        request->module = caller;
 
}
 
/** Cleanup after a module completes
 *
 */
static unlang_action_t unlang_module_done(rlm_rcode_t *p_result, request_t *request, unlang_stack_frame_t *frame)
{
        unlang_frame_state_module_t     *state = talloc_get_type_abort(frame->state, unlang_frame_state_module_t);
        rlm_rcode_t                     rcode = state->rcode_set ? state->rcode : *p_result;
 
#ifndef NDEBUG
        fr_assert(state->unlang_indent == request->log.indent.unlang);
#endif
 
        fr_assert(rcode >= RLM_MODULE_REJECT);
        fr_assert(rcode < RLM_MODULE_NOT_SET);
 
        RDEBUG("%s (%s)", frame->instruction->name ? frame->instruction->name : "",
               fr_table_str_by_value(mod_rcode_table, rcode, "<invalid>"));
 
        if (state->p_result) *state->p_result = rcode;  /* Inform our caller if we have one */
        *p_result = rcode;
        request->module = state->previous_module;
 
        return UNLANG_ACTION_CALCULATE_RESULT;
}
 
/** Cleanup after a yielded module completes
 *
 */
static unlang_action_t unlang_module_resume_done(rlm_rcode_t *p_result, request_t *request, unlang_stack_frame_t *frame)
{
        unlang_frame_state_module_t     *state = talloc_get_type_abort(frame->state, unlang_frame_state_module_t);
 
        state->thread->active_callers--;
 
        return unlang_module_done(p_result, request, frame);
}
 
/** Wrapper to call a module's resumption function
 *
 * This is called _after_ the module first yields, and again after any
 * other yields.
 */
static unlang_action_t unlang_module_resume(rlm_rcode_t *p_result, request_t *request, unlang_stack_frame_t *frame)
{
        unlang_frame_state_module_t     *state = talloc_get_type_abort(frame->state, unlang_frame_state_module_t);
        unlang_module_t                 *m = unlang_generic_to_module(frame->instruction);
        module_method_t                 resume;
        unlang_action_t                 ua;
 
        /*
         *      Update the rcode from any child calls that
         *      may have been performed. The module still
         *      has a chance to override this rcode if it
         *      wants, but process modules in particular
         *      expect to see the result of child
         *      evaluations available to them in p_result.
         */
        state->rcode = *p_result < RLM_MODULE_NUMCODES ? *p_result : RLM_MODULE_NOOP;
 
        fr_assert(state->resume != NULL);
 
        resume = state->resume;
 
        /*
         *      The module *MUST* explicitly set the resume
         *      function when yielding or pushing children
         *      if it wants to be called again later.
         */
        state->resume = NULL;
 
        /*
         *      Lock is noop unless instance->mutex is set.
         */
        safe_lock(m->mmc.mi);
        ua = resume(&state->rcode, MODULE_CTX(m->mmc.mi, state->thread->data,
                                              state->env_data, state->rctx), request);
        safe_unlock(m->mmc.mi);
 
        if (request->master_state == REQUEST_STOP_PROCESSING) ua = UNLANG_ACTION_STOP_PROCESSING;
 
        switch (ua) {
        case UNLANG_ACTION_STOP_PROCESSING:
                RWARN("Module %s or worker signalled to stop processing request", m->mmc.mi->name);
                if (state->p_result) *state->p_result = state->rcode;
                state->thread->active_callers--;
                *p_result = state->rcode;
                request->module = state->previous_module;
                return UNLANG_ACTION_STOP_PROCESSING;
 
        case UNLANG_ACTION_YIELD:
                /*
                 *      The module yielded but didn't set a
                 *      resume function, this means it's done
                 *      and when the I/O operation completes
                 *      it shouldn't be called again.
                 */
                if (!state->resume) {
                        frame_repeat(frame, unlang_module_resume_done);
                } else {
                        repeatable_set(frame);
                }
                return UNLANG_ACTION_YIELD;
 
        /*
         *      The module is done (for now).
         *      But, running it pushed one or more asynchronous
         *      calls onto the stack for evaluation.
         *      These need to be run before the module resumes
         *      or the next unlang instruction is processed.
         */
        case UNLANG_ACTION_PUSHED_CHILD:
                /*
                 *      The module pushed a child and didn't
                 *      set a resume function, this means
                 *      it's done, and we won't call it again
                 *      but we still need to do some cleanup
                 *      after the child returns.
                 */
                if (!state->resume) {
                        frame_repeat(frame, unlang_module_resume_done);
                        state->rcode_set = false;       /* Preserve the child rcode */
                } else {
                        repeatable_set(frame);
                }
                return UNLANG_ACTION_PUSHED_CHILD;
 
        case UNLANG_ACTION_CALCULATE_RESULT:
                /*
                 *      Module set a resume function but
                 *      didn't yield or push additional
                 *      children.
                 *
                 *      Evaluate the function now and
                 *      use the result as the final result.
                 */
                if (state->resume) return unlang_module_resume(p_result, request, frame);
                request->module = state->previous_module;
                break;
 
        case UNLANG_ACTION_UNWIND:
                request->module = state->previous_module;
                break;
 
        case UNLANG_ACTION_FAIL:
                *p_result = RLM_MODULE_FAIL;
                request->module = state->previous_module;
                break;
 
        case UNLANG_ACTION_EXECUTE_NEXT:        /* Not valid */
                fr_assert(0);
                *p_result = RLM_MODULE_FAIL;
                break;
        }
 
        unlang_module_resume_done(p_result, request, frame);
        request->module = state->previous_module;
 
        return ua;
}
 
/** Call the callback registered for a retry event
 *
 * @param[in] el        the event timer was inserted into.
 * @param[in] now       The current time, as held by the event_list.
 * @param[in] ctx       the stack frame
 *
 */
static void unlang_module_event_retry_handler(UNUSED fr_event_list_t *el, fr_time_t now, void *ctx)
{
        request_t                       *request = talloc_get_type_abort(ctx, request_t);
        unlang_stack_t                  *stack = request->stack;
        unlang_stack_frame_t            *frame = &stack->frame[stack->depth];
        unlang_frame_state_module_t     *state = talloc_get_type_abort(frame->state, unlang_frame_state_module_t);
 
        switch (fr_retry_next(&state->retry, now)) {
        case FR_RETRY_CONTINUE:
                if (state->retry_cb) {
                        /*
                         *      Call the module retry handler, with the state of the retry.  On MRD / MRC, the
                         *      module is made runnable again, and the "resume" function is called.
                         */
                        state->retry_cb(MODULE_CTX(state->mi, state->thread, state->env_data, state->rctx), state->request, &state->retry);
                } else {
                        /*
                         *      For signals, the module will get either a RETRY
                         *      signal, or a TIMEOUT signal (also for max count).
                         *
                         *      The signal handler should generally change the resume
                         *      function, and mark the request as runnable.  We
                         *      probably don't want the module to do tons of work in
                         *      the signal handler, as it's called from the event
                         *      loop.  And doing so could affect the other event
                         *      timers.
                         *
                         *      Note also that we call frame->signal(), and not
                         *      unlang_interpret_signal().  That is because we want to
                         *      signal only the module.  We know that the other frames
                         *      on the stack can't handle this particular signal.  So
                         *      there's no point in calling them.  Or, if sections
                         *      have their own retry handlers, then we don't want to
                         *      signal those _other_ retry handlers with _our_ signal.
                         */
                        frame->signal(request, frame, FR_SIGNAL_RETRY);
                }
 
                /*
                 *      Reset the timer.
                 */
                if (fr_event_timer_at(state, unlang_interpret_event_list(request), &state->ev, state->retry.next,
                                      unlang_module_event_retry_handler, request) < 0) {
                        RPEDEBUG("Failed inserting event");
                        unlang_interpret_mark_runnable(request); /* and let the caller figure out what's up */
                }
                return;
 
        case FR_RETRY_MRD:
                RDEBUG("Reached max_rtx_duration (%pVs > %pVs) - sending timeout",
                        fr_box_time_delta(fr_time_sub(now, state->retry.start)), fr_box_time_delta(state->retry.config->mrd));
                break;
 
        case FR_RETRY_MRC:
                RDEBUG("Reached max_rtx_count %u- sending timeout",
                        state->retry.config->mrc);
                break;
        }
 
        /*
         *      Run the retry handler on MRD / MRC, too.
         */
        if (state->retry_cb) {
                state->retry_cb(MODULE_CTX(state->mi, state->thread, state->env_data, state->rctx), state->request, &state->retry);
        } else {
                frame->signal(request, frame, FR_SIGNAL_TIMEOUT);
        }
 
        /*
         *      On final timeout, always mark the request as runnable.
         */
        unlang_interpret_mark_runnable(request);
}
 
static unlang_action_t unlang_module(rlm_rcode_t *p_result, request_t *request, unlang_stack_frame_t *frame)
{
        unlang_module_t                 *m;
        unlang_frame_state_module_t     *state = talloc_get_type_abort(frame->state, unlang_frame_state_module_t);
        unlang_action_t                 ua;
        fr_time_t                       now = fr_time_wrap(0);
 
        *p_result = state->rcode = RLM_MODULE_NOOP;
        state->rcode_set = true;
        state->previous_module = request->module;
 
#ifndef NDEBUG
        state->unlang_indent = request->log.indent.unlang;
#endif
        /*
         *      Process a stand-alone child, and fall through
         *      to dealing with it's parent.
         */
        m = unlang_generic_to_module(frame->instruction);
        fr_assert(m);
 
        RDEBUG4("[%i] %s - %s (%s)", stack_depth_current(request), __FUNCTION__,
                m->mmc.mi->module->exported->name, m->mmc.mi->name);
 
        state->p_result = NULL;
 
        /*
         *      Return administratively configured return code
         */
        if (m->mmc.mi->force) {
                state->rcode = m->mmc.mi->code;
                ua = UNLANG_ACTION_CALCULATE_RESULT;
                goto done;
        }
 
        if (m->mmc.mmb.method_env) {
                if (!state->env_data) {
                        ua = call_env_expand(state, request, &state->env_result, &state->env_data, m->call_env);
                        switch (ua) {
                        case UNLANG_ACTION_FAIL:
                                goto fail;
 
                        case UNLANG_ACTION_PUSHED_CHILD:
                                frame_repeat(frame, unlang_module);
                                return UNLANG_ACTION_PUSHED_CHILD;
 
                        default:
                                break;
                        }
                }
 
                /*
                 *      Fail the module call on callenv failure
                 */
                if (state->env_result != CALL_ENV_SUCCESS) RETURN_MODULE_FAIL;
        }
 
        /*
         *      Grab the thread/module specific data if any exists.
         */
        state->thread = module_thread(m->mmc.mi);
        fr_assert(state->thread != NULL);
 
        /*
         *      Don't allow returning _through_ modules
         */
        return_point_set(frame_current(request));
 
        /*
         *      For logging unresponsive children.
         */
        state->thread->total_calls++;
 
        /*
         *      If we're doing retries, remember when we started
         *      running the module.
         */
        if (fr_time_delta_ispos(frame->instruction->actions.retry.irt)) now = fr_time();
 
        request->module = m->mmc.mi->name;
        safe_lock(m->mmc.mi);   /* Noop unless instance->mutex set */
        ua = m->mmc.mmb.method(&state->rcode,
                               MODULE_CTX(m->mmc.mi, state->thread->data, state->env_data, NULL),
                               request);
        safe_unlock(m->mmc.mi);
 
        if (request->master_state == REQUEST_STOP_PROCESSING) ua = UNLANG_ACTION_STOP_PROCESSING;
 
        switch (ua) {
        /*
         *      It is now marked as "stop" when it wasn't before, we
         *      must have been blocked.
         */
        case UNLANG_ACTION_STOP_PROCESSING:
                RWARN("Module %s became unblocked", m->mmc.mi->name);
                if (state->p_result) *state->p_result = state->rcode;
                *p_result = state->rcode;
                request->module = state->previous_module;
                return UNLANG_ACTION_STOP_PROCESSING;
 
        case UNLANG_ACTION_YIELD:
                state->thread->active_callers++;
 
                /*
                 *      The module yielded but didn't set a
                 *      resume function, this means it's done
                 *      and when the I/O operation completes
                 *      it shouldn't be called again.
                 */
                if (!state->resume) {
                        frame_repeat(frame, unlang_module_resume_done);
                } else {
                        frame_repeat(frame, unlang_module_resume);
                }
 
                /*
                 *      If we have retry timers, then start the retries.
                 */
                if (fr_time_delta_ispos(frame->instruction->actions.retry.irt)) {
                        fr_assert(fr_time_gt(now, fr_time_wrap(0)));
 
                        fr_retry_init(&state->retry, now, &frame->instruction->actions.retry);
 
                        if (fr_event_timer_at(state, unlang_interpret_event_list(request),
                                              &state->ev, state->retry.next,
                                              unlang_module_event_retry_handler, request) < 0) {
                                RPEDEBUG("Failed inserting event");
                                goto fail;
                        }
                }
 
                return UNLANG_ACTION_YIELD;
 
        /*
         *      The module is done (for now).
         *      But, running it pushed one or more asynchronous
         *      calls onto the stack for evaluation.
         *      These need to be run before the module resumes
         *      or the next unlang instruction is processed.
         */
        case UNLANG_ACTION_PUSHED_CHILD:
                /*
                 *      The module pushed a child and didn't
                 *      set a resume function, this means
                 *      it's done, and we won't call it again
                 *      but we still need to do some cleanup
                 *      after the child returns.
                 */
                if (!state->resume) {
                        frame_repeat(frame, unlang_module_done);
                        state->rcode_set = false;       /* Preserve the child rcode */
                } else {
                        repeatable_set(frame);
                }
                return UNLANG_ACTION_PUSHED_CHILD;
 
        case UNLANG_ACTION_CALCULATE_RESULT:
                /*
                 *      Module set a resume function but
                 *      didn't yield or push additional
                 *      children.
                 *
                 *      Evaluate the function now and
                 *      use the result as the final result.
                 */
                if (state->resume) {
                        frame->process = unlang_module_resume;  /* unlang_module_resume will assume this is set */
                        return unlang_module_resume(p_result, request, frame);
                }
                break;
 
        case UNLANG_ACTION_UNWIND:
                break;
 
        case UNLANG_ACTION_FAIL:
        fail:
                *p_result = RLM_MODULE_FAIL;
                break;
 
        case UNLANG_ACTION_EXECUTE_NEXT:
                fr_assert(0);
                *p_result = RLM_MODULE_FAIL;
                break;
        }
 
done:
        request->module = state->previous_module;
        unlang_module_done(p_result, request, frame);
        return ua;
}
 
void unlang_module_init(void)
{
        unlang_register(UNLANG_TYPE_MODULE,
                           &(unlang_op_t){
                                .name = "module",
                                .interpret = unlang_module,
                                .rcode_set = true,
                                .signal = unlang_module_signal,
                                .frame_state_size = sizeof(unlang_frame_state_module_t),
                                .frame_state_type = "unlang_frame_state_module_t",
                           });
}