subrequest.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: 2dbbf1abc4ac573dc07271331ecef2d2d9fcb34f $
 *
 * @file unlang/subrequest.c
 * @brief Unlang "subrequest" and "detach" keyword evaluation.
 *
 * @copyright 2006-2019 The FreeRADIUS server project
 */
 
RCSID("$Id: 2dbbf1abc4ac573dc07271331ecef2d2d9fcb34f $")
 
#include <freeradius-devel/server/state.h>
#include <freeradius-devel/server/tmpl_dcursor.h>
#include "unlang_priv.h"
#include "interpret_priv.h"
#include "subrequest_priv.h"
#include "child_request_priv.h"
 
/** Send a signal from parent request to subrequest
 *
 */
static void unlang_subrequest_signal(request_t *request, unlang_stack_frame_t *frame, fr_signal_t action)
{
        unlang_child_request_t          *cr = talloc_get_type_abort(frame->state, unlang_child_request_t);
        request_t                       *child = talloc_get_type_abort(cr->request, request_t);
 
        switch (cr->state) {
        case CHILD_DETACHED:
                RDEBUG3("subrequest detached during its execution - Not sending signal to child");
                return;
 
        case CHILD_CANCELLED:
                RDEBUG3("subrequest is cancelled - Not sending signal to child");
                return;
 
        case CHILD_RUNNABLE:
                fr_assert_msg(!unlang_request_is_scheduled(request), "Parent cannot be runnable if child has not completed");
                break;
 
        default:
                break;
        }
 
        /*
         *      Parent should never receive a detach
         *      signal whilst the child is running.
         *
         *      Only the child receives a detach
         *      signal when the detach keyword is used.
         */
        fr_assert(action != FR_SIGNAL_DETACH);
 
        /*
         *      If the server is stopped, inside a breakpoint,
         *      whilst processing a child, on resumption both
         *      requests (parent and child) may need to be
         *      cancelled as they've both hit max request_time.
         *
         *      Sometimes the child will run to completion before
         *      the cancellation is processed, but the parent
         *      will still be cancelled.
         *
         *      When the parent is cancelled this function is
         *      executed, which will signal an already stopped
         *      child to cancel itself.
         *
         *      This triggers asserts in the time tracking code.
         *
         *      ...so we check to see if the child is done before
         *      sending a signal.
         */
        if (unlang_request_is_done(child)) return;
 
        /*
         *      Forward other signals to the child
         */
        unlang_interpret_signal(child, action);
}
 
/** Parent being resumed after a child completes
 *
 */
static unlang_action_t unlang_subrequest_parent_resume(UNUSED unlang_result_t *p_result, request_t *request,
                                                       unlang_stack_frame_t *frame)
{
        unlang_group_t                          *g = unlang_generic_to_group(frame->instruction);
        unlang_child_request_t                  *cr = talloc_get_type_abort(frame->state, unlang_child_request_t);
        request_t                               *child = cr->request;
        unlang_subrequest_t                     *gext;
 
        /*
         *      Child detached
         */
        if (cr->state == CHILD_DETACHED) {
                RDEBUG3("subrequest detached during its execution - Not updating rcode or reply attributes");
 
                /*
                 *      If the child detached the subrequest section
                 *      should become entirely transparent, and
                 *      should not update the section rcode.
                 */
                return UNLANG_ACTION_EXECUTE_NEXT;
        }
 
        RDEBUG3("subrequest completed with rcode %s",
                fr_table_str_by_value(mod_rcode_table, cr->result.rcode, "<invalid>"));
 
        /*
         *      If there's a no destination tmpl, we're done.
         */
        if (!child->reply) {
                unlang_subrequest_detach_and_free(&child);
                return UNLANG_ACTION_CALCULATE_RESULT;
        }
 
        /*
         *      Otherwise... copy reply attributes into the
         *      specified destination.
         */
        gext = unlang_group_to_subrequest(g);
        if (gext->dst) {
                fr_pair_t               *vp = NULL;
                tmpl_dcursor_ctx_t      cc;
                fr_dcursor_t            cursor;
 
                /*
                 *      Use callback to build missing destination container.
                 */
                vp = tmpl_dcursor_build_init(NULL, request, &cc, &cursor, request, gext->dst, tmpl_dcursor_pair_build, NULL);
                if (!vp) {
                        RPDEBUG("Discarding subrequest attributes - Failed allocating groups");
                        tmpl_dcursor_clear(&cc);
                        return UNLANG_ACTION_FAIL;
                }
 
                MEM(fr_pair_list_copy(vp, &vp->vp_group, &child->reply_pairs) >= 0);
 
                tmpl_dcursor_clear(&cc);
        }
 
        unlang_subrequest_detach_and_free(&child);
        return UNLANG_ACTION_CALCULATE_RESULT;
}
 
/** Allocates a new subrequest and initialises it
 *
 */
static unlang_action_t unlang_subrequest_init(unlang_result_t *p_result, request_t *request, unlang_stack_frame_t *frame)
{
        unlang_child_request_t  *cr = talloc_get_type_abort(frame->state, unlang_child_request_t);
        request_t               *child;
        fr_pair_t               *vp;
 
        unlang_group_t          *g;
        unlang_subrequest_t     *gext;
 
        /*
         *      This should only be set for manually pushed subrequests
         */
        fr_assert(!cr->config.free_child);
 
        /*
         *      Initialize the state
         */
        g = unlang_generic_to_group(frame->instruction);
        if (unlang_list_empty(&g->children)) RETURN_UNLANG_NOOP;
 
        gext = unlang_group_to_subrequest(g);
        child = unlang_io_subrequest_alloc(request, gext->dict, UNLANG_DETACHABLE);
        if (!child) {
        fail:
                talloc_free(child);
                return UNLANG_ACTION_FAIL;
        }
        /*
         *      Set the packet type.
         */
        MEM(vp = fr_pair_afrom_da(child->request_ctx, gext->attr_packet_type));
        if (gext->type_enum) {
                child->packet->code = vp->vp_uint32 = gext->type_enum->value->vb_uint32;
        } else {
                fr_dict_enum_value_t const      *type_enum;
                fr_pair_t               *attr;
 
                if (tmpl_find_vp(&attr, request, gext->vpt) < 0) {
                        RDEBUG("Failed finding attribute %s", gext->vpt->name);
                        goto fail;
                }
 
                if (tmpl_attr_tail_da(gext->vpt)->type == FR_TYPE_STRING) {
                        type_enum = fr_dict_enum_by_name(gext->attr_packet_type, attr->vp_strvalue, attr->vp_length);
                        if (!type_enum) {
                                RDEBUG("Unknown Packet-Type %pV", &attr->data);
                                goto fail;
                        }
 
                        child->packet->code = vp->vp_uint32 = type_enum->value->vb_uint32;
                } else {
                        fr_value_box_t box;
 
                        fr_value_box_init(&box, FR_TYPE_UINT32, NULL, false);
                        if (fr_value_box_cast(request, &box, FR_TYPE_UINT32, NULL, &attr->data) < 0) {
                                RDEBUG("Failed casting value from %pV to data type uint32", &attr->data);
                                goto fail;
                        }
 
                        /*
                         *      Check that the value is known to the server.
                         *
                         *      If it isn't known, then there's no
                         *      "recv foo" section for it and we can't
                         *      do anything with this packet.
                         */
                        type_enum = fr_dict_enum_by_value(gext->attr_packet_type, &box);
                        if (!type_enum) {
                                RDEBUG("Invalid value %pV for Packet-Type", &box);
                                goto fail;
                        }
 
                        child->packet->code = vp->vp_uint32 = box.vb_uint32;
                }
 
        }
        fr_pair_append(&child->request_pairs, vp);
 
        if ((gext->src) && (tmpl_copy_pair_children(child->request_ctx, &child->request_pairs, request, gext->src) < -1)) {
                RPEDEBUG("Failed copying source attributes into subrequest");
                goto fail;
        }
 
        /*
         *      Setup the child so it'll inform us when
         *      it resumes, or if it detaches.
         *
         *      frame->instruction should be consistent
         *      as it's allocated by the unlang compiler.
         */
        if (unlang_child_request_init(cr, cr, child, p_result, NULL, frame->instruction, false) < 0) goto fail;
 
        /*
         *      Push the first instruction the child's
         *      going to run.
         */
        if (unlang_interpret_push(NULL, child, unlang_list_head(&g->children),
                                  FRAME_CONF(RLM_MODULE_NOT_SET, UNLANG_SUB_FRAME),
                                  UNLANG_NEXT_SIBLING) < 0) goto fail;
 
        /*
         *      Finally, setup the function that will be
         *      called when the child indicates the
         *      parent should be resumed.
         */
        frame_repeat(frame, unlang_subrequest_parent_resume);
 
        /*
         *      This is a common function, either pushed
         *      onto the parent's stack, or called directly
         *      from the subrequest instruction..
         */
        return unlang_subrequest_child_run(p_result, request, frame);   /* returns UNLANG_ACTION_YIELD */
}
 
/** Free a child request, detaching it from its parent and freeing allocated memory
 *
 * @param[in] child to free.
 */
void unlang_subrequest_detach_and_free(request_t **child)
{
        request_t *request = *child;
 
        /*
         *      The interpeter is told about this subrequest via interpret_child_init() in
         *      unlang_subrequest_child_push_and_detach() etc.  The subrequest is managed by the interpreter,
         *      and we therefore have to remove it from the interpreter.  Otherwise, simply calling
         *      talloc_free() will leave a dangling pointer in the interpreter scheduler.
         *
         *      If the request is detached, then the interpreter sees that it's done, and de-schedules it.
         *
         *      unlang_interpret_request_done() isn't idempotent, so we have to check for the DONE state
         *      before calling it again.  unlang_interpret_request_done() then calls the "done_internal"
         *      callback, which informs the application of that fact.
         */
        if (!request_is_detached(request) && (request->master_state != REQUEST_DONE)) {
                unlang_interpret_request_done(request);
        }
 
        request_detach(request);
        talloc_free(request);
        *child = NULL;
}
 
/** Allocate a subrequest to run through a virtual server at some point in the future
 *
 * @param[in] parent            to hang sub request off of.
 * @param[in] namespace         the child will operate in.
 * @return
 *      - A new child request.
 *      - NULL on failure.
 */
request_t *unlang_subrequest_alloc(request_t *parent, fr_dict_t const *namespace)
{
        return unlang_io_subrequest_alloc(parent, namespace, UNLANG_NORMAL_CHILD);
}
 
 
/** Function to run in the context of the parent on resumption
 *
 * @note Only executes if unlang_subrequest_child_push was called, not with the normal subrequest keyword.
 */
static unlang_action_t unlang_subrequest_child_done(unlang_result_t *p_result, UNUSED request_t *request,
                                                    unlang_stack_frame_t *frame)
{
        unlang_child_request_t          *cr = talloc_get_type_abort(frame->state, unlang_child_request_t);
 
        /*
         *      Default to NOOP
         */
        if (cr->result.rcode == RLM_MODULE_NOT_SET) {
                cr->result.rcode = RLM_MODULE_NOOP;
                if (cr->p_result) {
                        *cr->p_result = cr->result;
                } else {
                        *p_result = cr->result;
                }
        }
 
        /*
         *      We can free the child here as we're its parent
         */
        if (cr->config.free_child) {
                if (request_is_detachable(cr->request)) {
                        unlang_subrequest_detach_and_free(&cr->request);
                } else {
                        TALLOC_FREE(cr->request);
                }
        }
 
        return UNLANG_ACTION_CALCULATE_RESULT;
}
 
/** Function called by the unlang interpreter, or manually to start the child running
 *
 * The reason why we do this on the unlang stack is so that _this_ frame
 * is marked as resumable in the parent, not whatever frame was previously
 * being processed by the interpreter when the parent was called.
 *
 * i.e. after calling unlang_subrequest_child_push, the code in the parent
 * can call UNLANG_ACTION_PUSHED_CHILD, which will result in _this_ frame
 * being executed, and _this_ frame can yield.
 *
 * @note Called from the parent to start a child running.
 */
unlang_action_t unlang_subrequest_child_run(UNUSED unlang_result_t *p_result, UNUSED request_t *request,
                                            unlang_stack_frame_t *frame)
{
        unlang_child_request_t          *cr = talloc_get_type_abort(frame->state, unlang_child_request_t);
        request_t                       *child = cr->request;
 
        /*
         *      No parent means this is a pre-detached child
         *      so the parent should continue executing.
         */
        if (!child || !child->parent) return UNLANG_ACTION_CALCULATE_RESULT;
 
 
        /*
         *      Ensure we restore the session state information
         *      into the child.
         */
        if (cr->config.session_unique_ptr) fr_state_restore_from_parent(child,
                                                                     cr->config.session_unique_ptr,
                                                                     cr->num);
        /*
         *      Ensures the child is setup correctly and adds
         *      it into the runnable queue of whatever owns
         *      the interpreter.
         */
        interpret_child_init(child);
 
        /*
         *      This function is being called by something
         *      other than the subrequest keyword.
         *
         *      Set a different resumption function that
         *      just writes the final rcode out.
         */
        if (frame->process == unlang_subrequest_child_run) {
                frame_repeat(frame, unlang_subrequest_child_done);
        }
 
        cr->state = CHILD_RUNNABLE;
 
        return UNLANG_ACTION_YIELD;
}
 
/** Push a pre-existing child back onto the stack as a subrequest
 *
 * The child *MUST* have been allocated with unlang_io_subrequest_alloc, or something
 * that calls it.
 *
 * After the child is no longer required it *MUST* be freed with #unlang_subrequest_detach_and_free.
 * It's not enough to free it with talloc_free.
 *
 * This function should be called _before_ pushing any additional frames onto the child's
 * stack for it to execute.
 *
 * The parent should return UNLANG_ACTION_PUSHED_CHILD, when it's done setting up the
 * child request.  It should NOT return UNLANG_ACTION_YIELD.
 *
 * @param[in] p_result                  Where to write the result of the subrequest.
 * @param[in] child                     to push.
 * @param[in] unique_session_ptr        Unique identifier for child's session data.
 * @param[in] free_child                automatically free the child when it's finished executing.
 *                                      This is useful if extracting the result from the child is
 *                                      done using the child's stack, and so the parent never needs
 *                                      to access it.
 * @param[in] top_frame                 Set to UNLANG_TOP_FRAME if the interpreter should return.
 *                                      Set to UNLANG_SUB_FRAME if the interpreter should continue.
 * @return
 *      - 0 on success.
 *      - -1 on failure.
 */
 
int unlang_subrequest_child_push(unlang_result_t *p_result, request_t *child, void const *unique_session_ptr, bool free_child, bool top_frame)
{
        unlang_child_request_t  *cr;
        unlang_stack_frame_t    *frame;
 
        static unlang_t subrequest_instruction = {
                .type = UNLANG_TYPE_SUBREQUEST,
                .name = "subrequest",
                .debug_name = "subrequest",
                .actions = DEFAULT_MOD_ACTIONS,
        };
 
        fr_assert_msg(free_child || child->parent, "Child's request pointer must not be NULL when calling subrequest_child_push");
 
        if (!fr_cond_assert_msg(stack_depth_current(child) == 0,
                                "Child stack depth must be 0 (not %d), when calling subrequest_child_push",
                                stack_depth_current(child))) return -1;
 
        /*
         *      Push a new subrequest frame onto the stack
         *      of the parent.
         *
         *      This allocates memory for the frame state
         *      which we fill in below.
         *
         *      This frame executes once the subrequest has
         *      completed.
         */
        if (unlang_interpret_push(NULL, child->parent, &subrequest_instruction,
                                  FRAME_CONF(RLM_MODULE_NOT_SET, top_frame), UNLANG_NEXT_STOP) < 0) {
                return -1;
        }
 
        frame = frame_current(child->parent);
        frame->process = unlang_subrequest_child_run;
 
        /*
         *      Setup the state for the subrequest
         */
        cr = talloc_get_type_abort(frame_current(child->parent)->state, unlang_child_request_t);
 
        /*
         *      Initialise our frame state, and push the first
         *      instruction onto the child's stack.
         *
         *      This instruction will mark the parent as runnable
         *      when it executed.
         */
        if (unlang_child_request_init(cr, cr, child, p_result, NULL, unique_session_ptr, free_child) < 0) {
                unwind_set(frame);
                return -1;
        }
 
        return 0;
}
 
/** Add a child request to the runnable queue
 *
 * @param[in] request           to add to the runnable queue.
 * @return
 *      - 0 on success.
 *      - -1 on failure.
 */
int unlang_subrequest_child_push_and_detach(request_t *request)
{
        /*
         *      Ensures the child is setup correctly and adds
         *      it into the runnable queue of whatever owns
         *      the interpreter.
         */
        interpret_child_init(request);
 
        if (request_detach(request) < 0) {
                RPEDEBUG("Failed detaching request");
                return -1;
        }
 
        return 0;
}
 
static unlang_t *unlang_compile_subrequest(unlang_t *parent, unlang_compile_ctx_t *unlang_ctx, CONF_ITEM const *ci)
{
        CONF_SECTION                    *cs = cf_item_to_section(ci);
        char const                      *name2;
 
        unlang_t                        *c;
 
        unlang_group_t                  *g;
        unlang_subrequest_t             *gext;
 
        unlang_compile_ctx_t            unlang_ctx2;
 
        tmpl_rules_t                    t_rules;
        fr_dict_autoload_talloc_t       *dict_ref = NULL;
 
        fr_dict_t const                 *dict;
        fr_dict_attr_t const            *attr_packet_type = NULL;
        fr_dict_enum_value_t const      *type_enum = NULL;
 
        fr_slen_t                       slen;
        char                            *namespace = NULL;
        char const                      *packet_name = NULL;
 
        tmpl_t                          *vpt = NULL, *src_vpt = NULL, *dst_vpt = NULL;
 
        if (!cf_item_next(cs, NULL)) return UNLANG_IGNORE;
 
        /*
         *      subrequest { ... }
         *
         *      Create a subrequest which is of the same dictionary
         *      and packet type as the current request.
         *
         *      We assume that the Packet-Type attribute exists.
         */
        name2 = cf_section_name2(cs);
        if (!name2) {
                dict = unlang_ctx->rules->attr.dict_def;
                packet_name = name2 = unlang_ctx->section_name2;
                attr_packet_type =  virtual_server_packet_type_by_cs(virtual_server_cs(unlang_ctx->vs));
                goto get_packet_type;
        }
 
        if (cf_section_name2_quote(cs) != T_BARE_WORD) {
                cf_log_err(cs, "The arguments to 'subrequest' must be a name or an attribute reference");
        print_url:
                cf_log_err(ci, DOC_KEYWORD_REF(subrequest));
                return NULL;
        }
 
        dict = unlang_ctx->rules->attr.dict_def;
 
        /*
         *      @foo is "dictionary foo", as with references in the dictionaries.
         *
         *      @foo::bar is "dictionary foo, Packet-Type = ::bar"
         *
         *      foo::bar is "dictionary foo, Packet-Type = ::bar"
         *
         *      ::bar is "this dictionary, Packet-Type = ::bar", BUT
         *      we don't try to parse the new dictionary name, as it
         *      doesn't exist.
         */
        if ((name2[0] == '@') ||
            ((name2[0] != ':') && (name2[0] != '&') && (strchr(name2 + 1, ':') != NULL))) {
                char *q;
 
                /*
                 *      This is a different protocol dictionary.  We reset the packet type.
                 *
                 *      @todo - the packet type should really be stored in #fr_dict_protocol_t.
                 */
                if (name2[0] == '@') {
                        attr_packet_type = NULL;
                        name2++;
                }
 
                MEM(namespace = talloc_strdup(parent, name2));
                q = namespace;
 
                while (fr_dict_attr_allowed_chars[(uint8_t) *q]) {
                        q++;
                }
                *q = '\0';
 
                dict = fr_dict_by_protocol_name(namespace);
                if (!dict) {
                        dict_ref = fr_dict_autoload_talloc(NULL, &dict, namespace);
                        if (!dict_ref) {
                                cf_log_err(cs, "Unknown namespace in '%s'", name2);
                                talloc_free(namespace);
                                return NULL;
                        }
                }
 
                /*
                 *      Skip the dictionary name, and go to the thing
                 *      right after it.
                 */
                name2 += (q - namespace);
                TALLOC_FREE(namespace);
        }
 
        /*
         *      @dict::enum is "other dictionary, Packet-Type = ::enum"
         *      ::enum is this dictionary, "Packet-Type = ::enum"
         */
        if ((name2[0] == ':') && (name2[1] == ':')) {
                packet_name = name2;
                goto get_packet_type;
        }
 
        /*
         *      Can't do foo.bar.baz::foo, the enums are only used for Packet-Type.
         */
        if (strchr(name2, ':') != NULL) {
                cf_log_err(cs, "Reference cannot contain enum value in '%s'", name2);
                return NULL;
        }
 
        /*
         *      Bare words are attribute references.
         */
        slen = tmpl_afrom_attr_substr(parent, NULL, &vpt,
                                      &FR_SBUFF_IN(name2, talloc_strlen(name2)),
                                      NULL, unlang_ctx->rules);
        if (slen <= 0) {
                cf_log_perr(cs, "Invalid argument to 'subrequest', failed parsing packet-type");
                goto print_url;
        }
 
        fr_assert(tmpl_is_attr(vpt));
 
        /*
         *      Anything resembling an integer or string is
         *      OK.  Nothing else makes sense.
         */
        switch (tmpl_attr_tail_da(vpt)->type) {
        case FR_TYPE_INTEGER_EXCEPT_BOOL:
        case FR_TYPE_STRING:
                break;
 
        default:
                talloc_free(vpt);
                cf_log_err(cs, "Invalid data type for attribute %s.  "
                           "Must be an integer type or string", name2 + 1);
                goto print_url;
        }
 
        dict = unlang_ctx->rules->attr.dict_def;
        packet_name = NULL;
 
get_packet_type:
        /*
         *      Local attributes cannot be used in a subrequest.  They belong to the parent.  Local attributes
         *      are NOT copied to the subrequest.
         *
         *      @todo - maybe we want to copy local variables, too?  But there may be multiple nested local
         *      variables, each with their own dictionary.
         */
        dict = fr_dict_proto_dict(dict);
 
        /*
         *      We're switching virtual servers, find the packet type by name.
         */
        if (!attr_packet_type) {
                attr_packet_type =  fr_dict_attr_by_name(NULL, fr_dict_root(dict), "Packet-Type");
                if (!attr_packet_type) {
                        cf_log_err(cs, "No such attribute 'Packet-Type' in namespace '%s'", fr_dict_root(dict)->name);
        error:
                        talloc_free(namespace);
                        talloc_free(vpt);
                        talloc_free(dict_ref);
                        goto print_url;
                }
        }
 
        if (packet_name) {
                /*
                 *      Allow ::enum-name for packet types
                 */
                if ((packet_name[0] == ':') && (packet_name[1] == ':')) packet_name += 2;
 
                type_enum = fr_dict_enum_by_name(attr_packet_type, packet_name, -1);
                if (!type_enum) {
                        cf_log_err(cs, "No such value '%s' for attribute '%s' in namespace '%s'",
                                   packet_name, attr_packet_type->name, fr_dict_root(dict)->name);
                        goto error;
                }
        }
 
        /*
         *      No longer needed
         */
        talloc_free(namespace);
 
        /*
         *      Source and destination arguments
         */
        {
                char const      *dst, *src;
 
                src = cf_section_argv(cs, 0);
                if (src) {
                        RULES_VERIFY(unlang_ctx->rules);
 
                        (void) tmpl_afrom_substr(parent, &src_vpt,
                                                 &FR_SBUFF_IN(src, talloc_strlen(src)),
                                                 cf_section_argv_quote(cs, 0), NULL, unlang_ctx->rules);
                        if (!src_vpt) {
                                cf_log_perr(cs, "Invalid argument to 'subrequest', failed parsing src");
                                goto error;
                        }
 
                        if (!tmpl_contains_attr(src_vpt)) {
                                cf_log_err(cs, "Invalid argument to 'subrequest' src must be an attr or list, got %s",
                                           tmpl_type_to_str(src_vpt->type));
                                talloc_free(src_vpt);
                                goto error;
                        }
 
                        dst = cf_section_argv(cs, 1);
                        if (dst) {
                                RULES_VERIFY(unlang_ctx->rules);
 
                                (void) tmpl_afrom_substr(parent, &dst_vpt,
                                                         &FR_SBUFF_IN(dst, talloc_strlen(dst)),
                                                         cf_section_argv_quote(cs, 1), NULL, unlang_ctx->rules);
                                if (!dst_vpt) {
                                        cf_log_perr(cs, "Invalid argument to 'subrequest', failed parsing dst");
                                        goto error;
                                }
 
                                if (!tmpl_contains_attr(dst_vpt)) {
                                        cf_log_err(cs, "Invalid argument to 'subrequest' dst must be an "
                                                   "attr or list, got %s",
                                                   tmpl_type_to_str(dst_vpt->type));
                                        talloc_free(src_vpt);
                                        talloc_free(dst_vpt);
                                        goto error;
                                }
                        }
                }
        }
 
        if (!cf_item_next(cs, NULL)) {
                talloc_free(vpt);
                talloc_free(src_vpt);
                talloc_free(dst_vpt);
                return UNLANG_IGNORE;
        }
 
        t_rules = *unlang_ctx->rules;
        t_rules.parent = unlang_ctx->rules;
        t_rules.attr.dict_def = dict;
        t_rules.attr.allow_foreign = false;
 
        /*
         *      Copy over the compilation context.  This is mostly
         *      just to ensure that retry is handled correctly.
         *      i.e. reset.
         */
        unlang_compile_ctx_copy(&unlang_ctx2, unlang_ctx);
 
        /*
         *      Then over-write the new compilation context.
         */
        unlang_ctx2.section_name1 = "subrequest";
        unlang_ctx2.section_name2 = name2;
        unlang_ctx2.rules = &t_rules;
 
        /*
         *      Compile the subsection with a *different* default dictionary.
         */
        c = unlang_compile_section(parent, &unlang_ctx2, cs, UNLANG_TYPE_SUBREQUEST);
        if (!c) return NULL;
 
        /*
         *      Set the dictionary and packet information, which tells
         *      unlang_subrequest() how to process the request.
         */
        g = unlang_generic_to_group(c);
        gext = unlang_group_to_subrequest(g);
 
        if (dict_ref) {
                /*
                 *      Parent the dictionary reference correctly now that we
                 *      have the section with the dependency.  This should
                 *      be fast as dict_ref has no siblings.
                 */
                talloc_steal(gext, dict_ref);
        }
        if (vpt) gext->vpt = talloc_steal(gext, vpt);
 
        gext->dict = dict;
        gext->attr_packet_type = attr_packet_type;
        gext->type_enum = type_enum;
        gext->src = src_vpt;
        gext->dst = dst_vpt;
 
        return c;
}
 
 
/** Initialise subrequest ops
 *
 */
int unlang_subrequest_op_init(void)
{
        unlang_register(&(unlang_op_t) {
                        .name = "subrequest",
                        .type = UNLANG_TYPE_SUBREQUEST,
 
                        /*
                         *      Frame can't be cancelled, because children need to
                         *      write out status to the parent.  If we don't do this,
                         *      then all children must be detachable and must detach
                         *      so they don't try and write out status to a "done"
                         *      parent.
                         *
                         *      It's easier to allow the child/parent relationship
                         *      to end normally so that non-detachable requests are
                         *      guaranteed the parent still exists.
                                 */
                        .flag = (unlang_op_flag_t)(UNLANG_OP_FLAG_DEBUG_BRACES | UNLANG_OP_FLAG_RCODE_SET | UNLANG_OP_FLAG_NO_FORCE_UNWIND),
 
                        .compile = unlang_compile_subrequest,
                        .interpret = unlang_subrequest_init,
                        .signal = unlang_subrequest_signal,
 
                        .unlang_size = sizeof(unlang_subrequest_t),
                        .unlang_name = "unlang_subrequest_t",
                        .pool_headers = (TMPL_POOL_DEF_HEADERS * 3),
                        .pool_len = (TMPL_POOL_DEF_LEN * 3),
 
                        .frame_state_size = sizeof(unlang_child_request_t),
                        .frame_state_type = "unlang_child_request_t",
                });
 
        if (unlang_child_request_op_init() < 0) return -1;
 
        return 0;
}