xlat_eval.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: 1427de2dae43213a82a7c1837a5007bf8f121b56 $
 *
 * @file xlat_eval.c
 * @brief String expansion ("translation").  Evaluation of pre-parsed xlat expansions.
 *
 * @copyright 2018-2021 Arran Cudbard-Bell (a.cudbardb@freeradius.org)
 * @copyright 2000,2006 The FreeRADIUS server project
 * @copyright 2000 Alan DeKok (aland@freeradius.org)
 */
RCSID("$Id: 1427de2dae43213a82a7c1837a5007bf8f121b56 $")
 
#include <freeradius-devel/server/base.h>
#include <freeradius-devel/unlang/xlat.h>
#include <freeradius-devel/unlang/xlat_priv.h>
#include <freeradius-devel/util/debug.h>
#include <freeradius-devel/util/types.h>
#include <freeradius-devel/util/sbuff.h>
#include <freeradius-devel/util/value.h>
 
static int instance_count = 0;
 
static fr_dict_t const *dict_freeradius;
 
static fr_dict_autoload_t xlat_eval_dict[] = {
        { .out = &dict_freeradius, .proto = "freeradius" },
        { NULL }
};
 
fr_dict_attr_t const *attr_expr_bool_enum; /* xlat_expr.c */
fr_dict_attr_t const *attr_cast_base; /* xlat_expr.c */
 
static fr_dict_attr_t const *attr_cast_time_res_sec;
static fr_dict_attr_t const *attr_cast_time_res_min;
static fr_dict_attr_t const *attr_cast_time_res_hour;
static fr_dict_attr_t const *attr_cast_time_res_day;
static fr_dict_attr_t const *attr_cast_time_res_week;
static fr_dict_attr_t const *attr_cast_time_res_month;
static fr_dict_attr_t const *attr_cast_time_res_year;
static fr_dict_attr_t const *attr_cast_time_res_csec;
static fr_dict_attr_t const *attr_cast_time_res_msec;
static fr_dict_attr_t const *attr_cast_time_res_usec;
static fr_dict_attr_t const *attr_cast_time_res_nsec;
 
static fr_dict_attr_autoload_t xlat_eval_dict_attr[] = {
        { .out = &attr_expr_bool_enum, .name = "Expr-Bool-Enum", .type = FR_TYPE_BOOL, .dict = &dict_freeradius },
        { .out = &attr_cast_base, .name = "Cast-Base", .type = FR_TYPE_UINT8, .dict = &dict_freeradius },
 
        { .out = &attr_cast_time_res_sec, .name = "Cast-Time-Res-Sec", .type = FR_TYPE_TIME_DELTA, .dict = &dict_freeradius },
        { .out = &attr_cast_time_res_min, .name = "Cast-Time-Res-Min", .type = FR_TYPE_TIME_DELTA, .dict = &dict_freeradius },
        { .out = &attr_cast_time_res_hour, .name = "Cast-Time-Res-Hour", .type = FR_TYPE_TIME_DELTA, .dict = &dict_freeradius },
        { .out = &attr_cast_time_res_day, .name = "Cast-Time-Res-Day", .type = FR_TYPE_TIME_DELTA, .dict = &dict_freeradius },
        { .out = &attr_cast_time_res_week, .name = "Cast-Time-Res-Week", .type = FR_TYPE_TIME_DELTA, .dict = &dict_freeradius },
        { .out = &attr_cast_time_res_month, .name = "Cast-Time-Res-Month", .type = FR_TYPE_TIME_DELTA, .dict = &dict_freeradius },
        { .out = &attr_cast_time_res_year, .name = "Cast-Time-Res-Year", .type = FR_TYPE_TIME_DELTA, .dict = &dict_freeradius },
        { .out = &attr_cast_time_res_csec, .name = "Cast-Time-Res-Centi-Sec", .type = FR_TYPE_TIME_DELTA, .dict = &dict_freeradius },
        { .out = &attr_cast_time_res_msec, .name = "Cast-Time-Res-Milli-Sec", .type = FR_TYPE_TIME_DELTA, .dict = &dict_freeradius },
        { .out = &attr_cast_time_res_usec, .name = "Cast-Time-Res-Micro-Sec", .type = FR_TYPE_TIME_DELTA, .dict = &dict_freeradius },
        { .out = &attr_cast_time_res_nsec, .name = "Cast-Time-Res-Nano-Sec", .type = FR_TYPE_TIME_DELTA, .dict = &dict_freeradius },
 
        { NULL }
};
 
fr_table_num_sorted_t const xlat_action_table[] = {
        { L("done"),            XLAT_ACTION_DONE        },
        { L("fail"),            XLAT_ACTION_FAIL        },
        { L("push-child"),      XLAT_ACTION_PUSH_CHILD  },
        { L("yield"),           XLAT_ACTION_YIELD       }
};
size_t xlat_action_table_len = NUM_ELEMENTS(xlat_action_table);
 
/*
 *      This should be updated if fr_time_precision_table[] adds more time resolutions.
 */
static fr_table_ptr_ordered_t const xlat_time_precision_table[] = {
        { L("microseconds"),    &attr_cast_time_res_usec },
        { L("us"),              &attr_cast_time_res_usec },
 
        { L("nanoseconds"),     &attr_cast_time_res_nsec },
        { L("ns"),              &attr_cast_time_res_nsec },
 
        { L("milliseconds"),    &attr_cast_time_res_msec },
        { L("ms"),              &attr_cast_time_res_msec },
 
        { L("centiseconds"),    &attr_cast_time_res_csec },
        { L("cs"),              &attr_cast_time_res_csec },
 
        { L("seconds"),         &attr_cast_time_res_sec },
        { L("s"),               &attr_cast_time_res_sec },
 
        { L("minutes"),         &attr_cast_time_res_min },
        { L("m"),               &attr_cast_time_res_min },
 
        { L("hours"),           &attr_cast_time_res_hour },
        { L("h"),               &attr_cast_time_res_hour },
 
        { L("days"),            &attr_cast_time_res_day },
        { L("d"),               &attr_cast_time_res_day },
 
        { L("weeks"),           &attr_cast_time_res_week },
        { L("w"),               &attr_cast_time_res_week },
 
        /*
         *      These use special values FR_TIME_DUR_MONTH and FR_TIME_DUR_YEAR
         */
        { L("months"),          &attr_cast_time_res_month },
        { L("M"),               &attr_cast_time_res_month },
 
        { L("years"),           &attr_cast_time_res_year },
        { L("y"),               &attr_cast_time_res_year },
 
};
static size_t xlat_time_precision_table_len = NUM_ELEMENTS(xlat_time_precision_table);
 
fr_dict_attr_t const *xlat_time_res_attr(char const *res)
{
        fr_dict_attr_t const **da_p;
 
        da_p = fr_table_value_by_str(xlat_time_precision_table, res, NULL);
        if (!da_p) return NULL;
 
        return *da_p;
}
 
static ssize_t xlat_eval_sync(TALLOC_CTX *ctx, char **out, request_t *request, xlat_exp_head_t const * const head,
                              xlat_escape_legacy_t escape, void  const *escape_ctx);
 
/** Reconstruct the original expansion string from an xlat tree
 *
 * @param[in] out       sbuff to print result in.
 * @param[in] node      in the tree to start printing.
 * @return
 *      - The original expansion string on success.
 *      - NULL on error.
 */
static fr_slen_t xlat_fmt_print(fr_sbuff_t *out, xlat_exp_t const *node)
{
        switch (node->type) {
        case XLAT_BOX:
        case XLAT_GROUP:
                fr_assert(node->fmt != NULL);
                return fr_sbuff_in_sprintf(out, "%pV", fr_box_strvalue_buffer(node->fmt));
 
        case XLAT_ONE_LETTER:
                fr_assert(node->fmt != NULL);
                return fr_sbuff_in_sprintf(out, "%%%s", node->fmt);
 
        case XLAT_TMPL:
                fr_assert(node->fmt != NULL);
                if (tmpl_is_attr(node->vpt) && (node->fmt[0] == '&')) {
                        return fr_sbuff_in_strcpy(out, node->fmt);
                } else {
                        return fr_sbuff_in_sprintf(out, "%%{%pV}", fr_box_strvalue_buffer(node->fmt));
                }
 
#ifdef HAVE_REGEX
        case XLAT_REGEX:
                return fr_sbuff_in_sprintf(out, "%%{%u}", node->regex_index);
#endif
 
        case XLAT_FUNC:
        {
                bool                    first_done = false;
                fr_sbuff_t              our_out;
                fr_slen_t               slen;
 
                /*
                 *      No arguments, just print an empty function.
                 */
                if (!xlat_exp_head(node->call.args)) return fr_sbuff_in_sprintf(out, "%%%s()", node->call.func->name);
 
                our_out = FR_SBUFF(out);
                FR_SBUFF_IN_SPRINTF_RETURN(&our_out, "%%%s(", node->call.func->name);
 
                xlat_exp_foreach(node->call.args, arg) {
                        if ((first_done) && (node->call.func->input_type == XLAT_INPUT_ARGS)) {
                                FR_SBUFF_IN_CHAR_RETURN(&our_out, ',');
                        }
 
                        slen = xlat_fmt_print(&our_out, arg);
                        if (slen < 0) return slen - fr_sbuff_used(&our_out);
 
                        first_done = true;
                }
 
                FR_SBUFF_IN_CHAR_RETURN(&our_out, ')');
                return fr_sbuff_set(out, &our_out);
        }
 
        default:
                return 0;
        }
}
 
/** Output what we're currently expanding
 *
 * @param[in] request   The current request.
 * @param[in] node      Being processed.
 * @param[in] args      from previous expansion.
 * @param[in] line      Unused
 */
static inline void xlat_debug_log_expansion(request_t *request, xlat_exp_t const *node, fr_value_box_list_t const *args, UNUSED int line)
{
        if (node->flags.constant) return;
 
        if (!RDEBUG_ENABLED2) return;
 
        /*
         *      Because it's difficult to keep track of what
         *      the function was actually called with,
         *      we print the concatenated arguments list as
         *      well as the original fmt string.
         */
        if ((node->type == XLAT_FUNC) && !xlat_is_literal(node->call.args)) {
                RDEBUG2("| %%%s(%pM)", node->call.func->name, args);
        } else {
                fr_sbuff_t *agg;
 
                FR_SBUFF_TALLOC_THREAD_LOCAL(&agg, 1024, SIZE_MAX);
 
                if (xlat_fmt_print(agg, node) < 0) {
                        RERROR("Failed printing expansion");
                        return;
                }
                RDEBUG2("| %s", fr_sbuff_start(agg)); /* print line number here for debugging */
        }
}
 
/** Output the list result of an expansion
 *
 * @param[in] request   The current request.
 * @param[in] node      which was expanded.
 * @param[in] result    of the expansion.
 */
static inline void xlat_debug_log_list_result(request_t *request, xlat_exp_t const *node, fr_value_box_list_t const *result)
{
        if (node->flags.constant) return;
 
        if (!RDEBUG_ENABLED2) return;
 
        RDEBUG2("| --> %pM", result);
}
 
/** Output the result of an expansion
 *
 * @param[in] request   The current request.
 * @param[in] node      which was expanded.
 * @param[in] result    of the expansion.
 */
static inline void xlat_debug_log_result(request_t *request, xlat_exp_t const *node, fr_value_box_t const *result)
{
        if (node->flags.constant) return;
 
        if (!RDEBUG_ENABLED2) return;
 
        RDEBUG2("| --> %pV", result);
}
 
/** Process an individual xlat argument value box group
 *
 * @param[in] ctx       to allocate any additional buffers in
 * @param[in,out] list  of value boxes representing one argument
 * @param[in] request   currently being processed
 * @param[in] name      of the function being called
 * @param[in] arg       specification of current argument
 * @param[in] arg_num   number of current argument in the argument specifications
 * @return
 *      - XLAT_ACTION_DONE on success.
 *      - XLAT_ACTION_FAIL on failure.
 */
static xlat_action_t xlat_process_arg_list(TALLOC_CTX *ctx, fr_value_box_list_t *list, request_t *request,
                                           char const *name, xlat_arg_parser_t const *arg, unsigned int arg_num)
{
        fr_value_box_t *vb;
 
#define ESCAPE(_arg, _vb, _arg_num) \
do { \
        if ((_arg)->func && (!(_vb)->safe_for || !fr_value_box_is_safe_for((_vb), (_arg)->safe_for) || (_arg)->always_escape)) { \
                if ((_arg)->func(request, _vb, (_arg)->uctx) < 0) { \
                        RPEDEBUG("Function \"%s\" failed escaping argument %u", name, _arg_num); \
                        return XLAT_ACTION_FAIL; \
                } \
                fr_value_box_mark_safe_for((_vb), (_arg)->safe_for); \
        } \
} while (0)
 
        if (fr_value_box_list_empty(list)) {
                if (arg->required) {
                        REDEBUG("Function \"%s\" is missing required argument %u", name, arg_num);
                        return XLAT_ACTION_FAIL;
                }
                return XLAT_ACTION_DONE;
        }
 
        vb = fr_value_box_list_head(list);
 
        /*
         *      Concatenate child boxes, casting to desired type,
         *      then replace group vb with first child vb
         */
        if (arg->concat) {
                if (arg->func) {
                        do ESCAPE(arg, vb, arg_num); while ((vb = fr_value_box_list_next(list, vb)));
 
                        vb = fr_value_box_list_head(list);      /* Reset */
                }
 
                if (fr_value_box_list_concat_in_place(ctx,
                                                      vb, list, arg->type,
                                                      FR_VALUE_BOX_LIST_FREE, true,
                                                      SIZE_MAX) < 0) {
                        RPEDEBUG("Function \"%s\" failed concatenating arguments to type %s", name, fr_type_to_str(arg->type));
                        return XLAT_ACTION_FAIL;
                }
                fr_assert(fr_value_box_list_num_elements(list) <= 1);
 
                return XLAT_ACTION_DONE;
        }
 
        /*
         *      Only a single child box is valid here.  Check there is
         *      just one, cast to the correct type
         */
        if (arg->single) {
                if (fr_value_box_list_num_elements(list) > 1) {
                        RPEDEBUG("Function \"%s\" was provided an incorrect number of values at argument %u, "
                                 "expected %s got %u",
                                 name, arg_num,
                                 arg->required ? "0-1" : "1",
                                 fr_value_box_list_num_elements(list));
                        return XLAT_ACTION_FAIL;
                }
 
                ESCAPE(arg, vb, arg_num);
 
                if ((arg->type != FR_TYPE_VOID) && (vb->type != arg->type)) {
                cast_error:
                        if (fr_value_box_cast_in_place(ctx, vb,
                                                       arg->type, NULL) < 0) {
                                RPEDEBUG("Function \"%s\" failed to cast argument %u to type %s", name, arg_num, fr_type_to_str(arg->type));
                                return XLAT_ACTION_FAIL;
                        }
                }
 
                return XLAT_ACTION_DONE;
        }
 
        /*
         *      We're neither concatenating nor do we only expect a single value,
         *      cast all child values to the required type.
         */
        if (arg->type != FR_TYPE_VOID) {
                do {
                        ESCAPE(arg, vb, arg_num);
                        if (vb->type == arg->type) continue;
                        if (fr_value_box_cast_in_place(ctx, vb,
                                                       arg->type, NULL) < 0) goto cast_error;
                } while ((vb = fr_value_box_list_next(list, vb)));
 
        /*
         *      If it's not a void type we still need to escape the values
         */
        } else if (arg->func) {
                do ESCAPE(arg, vb, arg_num); while ((vb = fr_value_box_list_next(list, vb)));
        }
 
#undef ESCAPE
 
        return XLAT_ACTION_DONE;
}
 
 
/** Process list of boxed values provided as input to an xlat
 *
 * Ensures that the value boxes passed to an xlat function match the
 * requirements listed in its "args", and escapes any tainted boxes
 * using the specified escaping routine.
 *
 * @param[in] ctx               in which to allocate any buffers.
 * @param[in,out] list          value boxes provided as input.
 *                              List will be modified in accordance to rules
 *                              provided in the args array.
 * @param[in] request           being processed.
 * @param[in] func              to call
 */
static inline CC_HINT(always_inline)
xlat_action_t xlat_process_args(TALLOC_CTX *ctx, fr_value_box_list_t *list,
                                request_t *request, xlat_t const *func)
{
        xlat_arg_parser_t const *arg_p = func->args;
        xlat_action_t           xa;
        fr_value_box_t          *vb, *next;
 
        /*
         *      No args registered for this xlat
         */
        if (!func->args) return XLAT_ACTION_DONE;
 
        /*
         *      xlat needs no input processing just return.
         */
        switch (func->input_type) {
        case XLAT_INPUT_UNPROCESSED:
                return XLAT_ACTION_DONE;
 
        /*
         *      xlat takes all input as a single vb.
         */
        case XLAT_INPUT_ARGS:
                vb = fr_value_box_list_head(list);
                while (arg_p->type != FR_TYPE_NULL) {
                        /*
                         *      Separate check to see if the group
                         *      box is there.  Check in
                         *      xlat_process_arg_list verifies it
                         *      has a value.
                         */
                        if (!vb) {
                                if (arg_p->required) {
                                missing:
                                        REDEBUG("Function \"%s\" is missing required argument %u",
                                                 func->name, (unsigned int)((arg_p - func->args) + 1));
                                        return XLAT_ACTION_FAIL;
                                }
 
                                /*
                                 *      The argument isn't required.  Just omit it.  xlat_func_args_set() enforces
                                 *      that optional arguments are at the end of the argument list.
                                 */
                                return XLAT_ACTION_DONE;
                        }
 
                        /*
                         *      Everything in the top level list should be
                         *      groups
                         */
                        if (!fr_cond_assert(vb->type == FR_TYPE_GROUP)) return XLAT_ACTION_FAIL;
 
                        /*
                         *      pre-advance, in case the vb is replaced
                         *      during processing.
                         */
                        next = fr_value_box_list_next(list, vb);
                        xa = xlat_process_arg_list(ctx, &vb->vb_group, request, func->name, arg_p,
                                                   (unsigned int)((arg_p - func->args) + 1));
                        if (xa != XLAT_ACTION_DONE) return xa;
 
                        /*
                         *      This argument doesn't exist.  That might be OK, or it may be a fatal error.
                         */
                        if (fr_value_box_list_empty(&vb->vb_group)) {
                                /*
                                 *      Variadic rules deal with empty boxes differently...
                                 */
                                switch (arg_p->variadic) {
                                case XLAT_ARG_VARIADIC_EMPTY_SQUASH:
                                        fr_value_box_list_talloc_free_head(list);
                                        goto do_next;
 
                                case XLAT_ARG_VARIADIC_EMPTY_KEEP:
                                        goto empty_ok;
 
                                case XLAT_ARG_VARIADIC_DISABLED:
                                        break;
                                }
 
                                /*
                                 *      Empty groups for optional arguments are OK, we can just stop processing the list.
                                 */
                                if (!arg_p->required) {
                                        /*
                                         *      If the caller doesn't care about the type, then we leave the
                                         *      empty group there.
                                         */
                                        if (arg_p->type == FR_TYPE_VOID) goto do_next;
 
                                        /*
                                         *      The caller does care about the type, and we don't have any
                                         *      matching data.  Omit this argument, and all arguments after it.
                                         *
                                         *      i.e. if the caller has 3 optional arguments, all
                                         *      FR_TYPE_UINT8, and the first one is missing, then we MUST
                                         *      either supply boxes all of FR_TYPE_UINT8, OR we supply nothing.
                                         *
                                         *      We can't supply a box of any other type, because the caller
                                         *      has declared that it wants FR_TYPE_UINT8, and is naively
                                         *      accessing the box as vb_uint8, hoping that it's being passed
                                         *      the right thing.
                                         */
                                        fr_value_box_list_talloc_free_head(list);
                                        break;
                                }
 
                                /*
                                 *      If the caller is expecting a particular type, then getting nothing is
                                 *      an error.
                                 *
                                 *      If the caller manually checks the input type, then we can leave it as
                                 *      an empty group.
                                 */
                                if (arg_p->type != FR_TYPE_VOID) goto missing;
                        }
 
                empty_ok:
                        /*
                         *      In some cases we replace the current argument with the head of the group.
                         *
                         *      xlat_process_arg_list() has already done concatenations for us.
                         */
                        if (arg_p->single || arg_p->concat) {
                                fr_value_box_t *head = fr_value_box_list_pop_head(&vb->vb_group);
 
                                /*
                                 *      If we're meant to be smashing the argument
                                 *      to a single box, but the group was empty,
                                 *      add a null box instead so ordering is maintained
                                 *      for subsequent boxes.
                                 */
                                if (!head) head = fr_value_box_alloc_null(ctx);
                                fr_value_box_list_replace(list, vb, head);
                                talloc_free(vb);
                        }
 
                do_next:
                        if (arg_p->variadic) {
                                if (!next) break;
                        } else {
                                arg_p++;
                        }
                        vb = next;
                }
                break;
        }
 
        return XLAT_ACTION_DONE;
}
 
/** Validate that the return values from an xlat function match what it registered
 *
 * @param[in] request   The current request.
 * @param[in] func      that was called.
 * @param[in] returned  the output list of the function.
 * @param[in] pos       current position in the output list.
 * @return
 *      - true - If return values were correct.
 *      - false - If the return values were incorrect.
 */
static inline CC_HINT(nonnull(1,2,3))
bool xlat_process_return(request_t *request, xlat_t const *func, fr_value_box_list_t const *returned, fr_value_box_t *pos)
{
        unsigned int count = 0;
 
        /*
         *  Nothing to validate.  We don't yet enforce that functions
         *  must return at least one instance of their type.
         */
        if (!pos || fr_type_is_void(func->return_type)) return true;
 
        if (fr_type_is_null(func->return_type)) {
                /* Dynamic expansion to get the right name */
                REDEBUG("%s return type registered as %s, but %s expansion produced data",
                        func->name, func->name, fr_type_to_str(func->return_type));
 
                /* We are not forgiving for debug builds */
                fr_assert_fail("Treating invalid return type as fatal");
 
                return false;
        }
 
        do {
                if (pos->type != func->return_type) {
                        REDEBUG("%s returned invalid result type at index %u.  Expected type %s, got type %s",
                                func->name, count, fr_type_to_str(func->return_type), fr_type_to_str(pos->type));
 
                        /* We are not forgiving for debug builds */
                        fr_assert_fail("Treating invalid return type as fatal");
                }
                fr_value_box_mark_safe_for(pos, func->return_safe_for); /* Always set this */
                count++;
        } while ((pos = fr_value_box_list_next(returned, pos)));
 
        return true;
}
 
/** One letter expansions
 *
 * @param[in] ctx       to allocate boxed value, and buffers in.
 * @param[out] out      Where to write the boxed value.
 * @param[in] request   The current request.
 * @param[in] letter    to expand.
 * @return
 *      - #XLAT_ACTION_FAIL     on memory allocation errors.
 *      - #XLAT_ACTION_DONE     if we're done processing this node.
 *
 */
static inline CC_HINT(always_inline)
xlat_action_t xlat_eval_one_letter(TALLOC_CTX *ctx, fr_value_box_list_t *out,
                                   request_t *request, char letter)
{
 
        char            buffer[64];
        struct tm       ts;
        time_t          now;
        fr_value_box_t  *value;
 
        now = fr_time_to_sec(request->packet->timestamp);
 
        switch (letter) {
        case '%':
                MEM(value = fr_value_box_alloc_null(ctx));
                if (fr_value_box_strdup(value, value, NULL, "%", false) < 0) return XLAT_ACTION_FAIL;
                break;
 
        /*
         *      RADIUS request values
         */
 
        case 'I': /* Request ID */
                MEM(value = fr_value_box_alloc(ctx, FR_TYPE_UINT32, NULL));
                value->datum.uint32 = request->packet->id;
                break;
 
        case 'n': /* Request number */
                MEM(value = fr_value_box_alloc(ctx, FR_TYPE_UINT64, NULL));
                value->datum.uint64 = request->number;
                break;
 
        case 's': /* First request in this sequence */
                MEM(value = fr_value_box_alloc(ctx, FR_TYPE_UINT64, NULL));
                value->datum.uint64 = request->seq_start;
                break;
 
        /*
         *      Current time
         */
 
        case 'c': /* Current epoch time seconds */
                /*
                 *      @todo - leave this as FR_TYPE_DATE, but add an enumv which changes the scale to
                 *      seconds?
                 */
                MEM(value = fr_value_box_alloc(ctx, FR_TYPE_UINT64, NULL));
                value->datum.uint64 = (uint64_t)fr_time_to_sec(fr_time());
                break;
 
        case 'C': /* Current epoch time microsecond component */
                /*
                 *      @todo - we probably should remove this now that we have FR_TYPE_DATE with scaling.
                 */
                MEM(value = fr_value_box_alloc(ctx, FR_TYPE_UINT64, NULL));
                value->datum.uint64 = (uint64_t)fr_time_to_usec(fr_time()) % 1000000;
                break;
 
        /*
         *      Time of the current request
         */
 
        case 'd': /* Request day */
                if (!localtime_r(&now, &ts)) {
                error:
                        REDEBUG("Failed converting packet timestamp to localtime: %s", fr_syserror(errno));
                        return XLAT_ACTION_FAIL;
                }
 
                MEM(value = fr_value_box_alloc(ctx, FR_TYPE_UINT8, NULL));
                value->datum.uint8 = ts.tm_mday;
                break;
 
        case 'D': /* Request date */
                if (!localtime_r(&now, &ts)) goto error;
 
                strftime(buffer, sizeof(buffer), "%Y%m%d", &ts);
 
                MEM(value = fr_value_box_alloc_null(ctx));
                if (fr_value_box_strdup(value, value, NULL, buffer, false) < 0) goto error;
                break;
 
        case 'e': /* Request second */
                if (!localtime_r(&now, &ts)) goto error;
 
                MEM(value = fr_value_box_alloc(ctx, FR_TYPE_UINT8, NULL));
                value->datum.uint8 = ts.tm_sec;
                break;
 
        case 'G': /* Request minute */
                if (!localtime_r(&now, &ts)) goto error;
 
                MEM(value = fr_value_box_alloc(ctx, FR_TYPE_UINT8, NULL));
                value->datum.uint8 = ts.tm_min;
                break;
 
        case 'H': /* Request hour */
                if (!localtime_r(&now, &ts)) goto error;
 
                MEM(value = fr_value_box_alloc(ctx, FR_TYPE_UINT8, NULL));
                value->datum.uint8 = ts.tm_hour;
                break;
 
        case 'l': /* Request timestamp as seconds since the epoch */
                /*
                 *      @todo - leave this as FR_TYPE_DATE, but add an enumv which changes the scale to
                 *      seconds?
                 */
                MEM(value = fr_value_box_alloc(ctx, FR_TYPE_UINT64, NULL));
                value->datum.uint64 = (uint64_t ) now;
                break;
 
        case 'm': /* Request month */
                if (!localtime_r(&now, &ts)) goto error;
 
                MEM(value = fr_value_box_alloc(ctx, FR_TYPE_UINT8, NULL));
                value->datum.uint8 = ts.tm_mon + 1;
                break;
 
        case 'M': /* Request time microsecond component */
                /*
                 *      @todo - we probably should remove this now that we have FR_TYPE_DATE with scaling.
                 */
                MEM(value = fr_value_box_alloc(ctx, FR_TYPE_UINT32, NULL));
                value->datum.uint32 = fr_time_to_msec(request->packet->timestamp) % 1000;
                break;
 
        case 'S': /* Request timestamp in SQL format */
                if (!localtime_r(&now, &ts)) goto error;
 
                strftime(buffer, sizeof(buffer), "%Y-%m-%d %H:%M:%S", &ts);
 
                MEM(value = fr_value_box_alloc_null(ctx));
                if (fr_value_box_strdup(value, value, NULL, buffer, false) < 0) goto error;
                break;
 
        case 't': /* Request timestamp in CTIME format */
        {
                char *p;
 
                CTIME_R(&now, buffer, sizeof(buffer));
                p = strchr(buffer, '\n');
                if (p) *p = '\0';
 
                MEM(value = fr_value_box_alloc_null(ctx));
                if (fr_value_box_strdup(value, value, NULL, buffer, false) < 0) goto error;
        }
                break;
 
        case 'T': /* Request timestamp in ISO format */
        {
                int len = 0;
 
                if (!gmtime_r(&now, &ts)) goto error;
 
                if (!(len = strftime(buffer, sizeof(buffer) - 1, "%Y-%m-%dT%H:%M:%S", &ts))) {
                        REDEBUG("Failed converting packet timestamp to gmtime: Buffer full");
                        return XLAT_ACTION_FAIL;
                }
                strcat(buffer, ".");
                len++;
                snprintf(buffer + len, sizeof(buffer) - len, "%03i",
                         (int) fr_time_to_msec(request->packet->timestamp) % 1000);
 
                MEM(value = fr_value_box_alloc_null(ctx));
                if (fr_value_box_strdup(value, value, NULL, buffer, false) < 0) goto error;
        }
                break;
 
        case 'Y': /* Request year */
                if (!localtime_r(&now, &ts)) goto error;
 
                MEM(value = fr_value_box_alloc(ctx, FR_TYPE_UINT16, NULL));
 
                value->datum.int16 = ts.tm_year + 1900;
                break;
 
        default:
                fr_assert_fail("%%%c is not a valid one letter expansion", letter);
                return XLAT_ACTION_FAIL;
        }
 
        fr_value_box_list_insert_tail(out, value);
 
        return XLAT_ACTION_DONE;
}
 
typedef struct {
        int                     status;
        fr_value_box_list_t     list;
} xlat_exec_rctx_t;
 
static xlat_action_t xlat_exec_resume(UNUSED TALLOC_CTX *ctx, fr_dcursor_t *out,
                                      xlat_ctx_t const *xctx,
                                      UNUSED request_t *request, UNUSED fr_value_box_list_t *in)
{
        xlat_exec_rctx_t *rctx = talloc_get_type_abort(xctx->rctx, xlat_exec_rctx_t);
 
        if (rctx->status != 0) {
                fr_strerror_printf("Program failed with status %d", rctx->status);
                return XLAT_ACTION_FAIL;
        }
 
        fr_value_box_list_move((fr_value_box_list_t *)out->dlist, &rctx->list);
 
        return XLAT_ACTION_DONE;
}
 
 
/** Signal an xlat function
 *
 * @param[in] signal            function to call.
 * @param[in] exp               Xlat node that previously yielded.
 * @param[in] request           The current request.
 * @param[in] rctx              Opaque (to us), resume ctx provided by the xlat function
 *                              when it yielded.
 * @param[in] action            What the request should do (the type of signal).
 */
void xlat_signal(xlat_func_signal_t signal, xlat_exp_t const *exp,
                 request_t *request, void *rctx, fr_signal_t action)
{
        xlat_thread_inst_t *t = xlat_thread_instance_find(exp);
 
        signal(XLAT_CTX(exp->call.inst, t->data, t->mctx, NULL, rctx), request, action);
}
 
static xlat_action_t xlat_null_resume(UNUSED TALLOC_CTX *ctx, UNUSED fr_dcursor_t *out,
                                      UNUSED xlat_ctx_t const *xctx,
                                      UNUSED request_t *request, UNUSED fr_value_box_list_t *in)
{
        return XLAT_ACTION_DONE;
}
 
/** Call an xlat's resumption method
 *
 * @param[in] ctx               to allocate value boxes in.
 * @param[out] out              a list of #fr_value_box_t to append to.
 * @param[out] child            to evaluate. If a child needs to be evaluated
 *                              by the caller, we return XLAT_ACTION_PUSH_CHILD
 *                              and place the child to be evaluated here.
 *                              Once evaluation is complete, the caller
 *                              should call us with the same #xlat_exp_t and the
 *                              result of the nested evaluation in result.
 * @param[in] request           the current request.
 * @param[in] head              of the list to evaluate
 * @param[in,out] in            xlat node to evaluate. Advanced as we process
 *                              additional #xlat_exp_t.
 * @param[in] result            Previously expanded arguments to this xlat function.
 * @param[in] resume            function to call.
 * @param[in] rctx              Opaque (to us), resume ctx provided by xlat function
 *                              when it yielded.
 */
xlat_action_t xlat_frame_eval_resume(TALLOC_CTX *ctx, fr_dcursor_t *out,
                                     xlat_exp_head_t const **child,
                                     request_t *request,  xlat_exp_head_t const *head, xlat_exp_t const **in,
                                     fr_value_box_list_t *result, xlat_func_t resume, void *rctx)
{
        xlat_action_t           xa;
        xlat_exp_t const        *node = *in;
 
        /*
         *      It's important that callbacks leave the result list
         *      in a valid state, as it leads to all kinds of hard
         *      to debug problems if they free or change elements
         *      and don't remove them from the list.
         */
        VALUE_BOX_LIST_VERIFY(result);
 
        if (node->type != XLAT_FUNC) {
                xa = resume(ctx, out, XLAT_CTX(NULL, NULL, NULL, NULL, rctx), request, result);
        } else {
                xlat_thread_inst_t *t;
                t = xlat_thread_instance_find(node);
                xa = resume(ctx, out, XLAT_CTX(node->call.inst->data, t->data, t->mctx, NULL, rctx), request, result);
                VALUE_BOX_LIST_VERIFY(result);
 
                RDEBUG2("| %%%s(...)", node->call.func->name);
        }
 
        switch (xa) {
        case XLAT_ACTION_YIELD:
                RDEBUG2("| (YIELD)");
                return xa;
 
        case XLAT_ACTION_DONE:
                if (unlang_xlat_yield(request, xlat_null_resume, NULL, 0, NULL) != XLAT_ACTION_YIELD) return XLAT_ACTION_FAIL;
 
                fr_dcursor_next(out);           /* Wind to the start of this functions output */
                if (node->call.func) {
                        RDEBUG2("| --> %pV", fr_dcursor_current(out));
                        if (!xlat_process_return(request, node->call.func, (fr_value_box_list_t *)out->dlist,
                                         fr_dcursor_current(out))) return XLAT_ACTION_FAIL;
                }
 
                /*
                 *      It's easier if we get xlat_frame_eval to continue evaluating the frame.
                 */
                *in = xlat_exp_next(head, *in); /* advance */
                return xlat_frame_eval(ctx, out, child, request, head, in);
 
        case XLAT_ACTION_PUSH_CHILD:
        case XLAT_ACTION_PUSH_UNLANG:
        case XLAT_ACTION_FAIL:
                break;
        }
 
        return xa;
}
 
/** Process the result of a previous nested expansion
 *
 * @param[in] ctx               to allocate value boxes in.
 * @param[out] out              a list of #fr_value_box_t to append to.
 * @param[out] child            to evaluate.  If a child needs to be evaluated
 *                              by the caller, we return XLAT_ACTION_PUSH_CHILD
 *                              and place the child to be evaluated here.
 *                              Once evaluation is complete, the caller
 *                              should call us with the same #xlat_exp_t and the
 *                              result of the nested evaluation in result.
 * @param[in] request           the current request.
 * @param[in] head              of the list to evaluate
 * @param[in,out] in            xlat node to evaluate.  Advanced as we process
 *                              additional #xlat_exp_t.
 * @param[in] env_data          Expanded call env.
 * @param[in] result            of a previous nested evaluation.
 */
xlat_action_t xlat_frame_eval_repeat(TALLOC_CTX *ctx, fr_dcursor_t *out,
                                     xlat_exp_head_t const **child,
                                     request_t *request, xlat_exp_head_t const *head, xlat_exp_t const **in,
                                     void *env_data, fr_value_box_list_t *result)
{
        xlat_exp_t const        *node = *in;
 
        fr_dcursor_tail(out);   /* Needed for reentrant behaviour and debugging */
 
        switch (node->type) {
        case XLAT_FUNC:
        {
                xlat_action_t           xa;
                xlat_thread_inst_t      *t;
                fr_value_box_list_t     result_copy;
 
                t = xlat_thread_instance_find(node);
                fr_assert(t);
 
                XLAT_DEBUG("** [%i] %s(func-async) - %%%s(%pM)",
                           unlang_interpret_stack_depth(request), __FUNCTION__,
                           node->fmt, result);
 
                VALUE_BOX_LIST_VERIFY(result);
 
                /*
                 *      Always need to init and free the
                 *      copy list as debug level could change
                 *      when the xlat function executes.
                 */
                fr_value_box_list_init(&result_copy);
 
                /*
                 *      Need to copy the input list in case
                 *      the async function mucks with it.
                 */
                if (RDEBUG_ENABLED2) fr_value_box_list_acopy(unlang_interpret_frame_talloc_ctx(request), &result_copy, result);
                xa = xlat_process_args(ctx, result, request, node->call.func);
                if (xa == XLAT_ACTION_FAIL) {
                        fr_value_box_list_talloc_free(&result_copy);
                        return xa;
                }
 
                VALUE_BOX_LIST_VERIFY(result);
                xa = node->call.func->func(ctx, out,
                                           XLAT_CTX(node->call.inst->data, t->data, t->mctx, env_data, NULL),
                                           request, result);
                VALUE_BOX_LIST_VERIFY(result);
 
                if (RDEBUG_ENABLED2) {
                        REXDENT();
                        xlat_debug_log_expansion(request, *in, &result_copy, __LINE__);
                        RINDENT();
                }
                fr_value_box_list_talloc_free(&result_copy);
 
                switch (xa) {
                case XLAT_ACTION_FAIL:
                        return xa;
 
                case XLAT_ACTION_PUSH_CHILD:
                        RDEBUG3("|   -- CHILD");
                        return xa;
 
                case XLAT_ACTION_PUSH_UNLANG:
                        RDEBUG3("|   -- UNLANG");
                        return xa;
 
                case XLAT_ACTION_YIELD:
                        RDEBUG3("|   -- YIELD");
                        return xa;
 
                case XLAT_ACTION_DONE:                          /* Process the result */
                        fr_dcursor_next(out);
 
                        /*
                         *      Don't print out results if there are no results.
                         */
                        if (!fr_type_is_void(node->call.func->return_type)) {
                                REXDENT();
                                xlat_debug_log_result(request, *in, fr_dcursor_current(out));
                                if (!xlat_process_return(request, node->call.func,
                                                         (fr_value_box_list_t *)out->dlist,
                                                         fr_dcursor_current(out))) {
                                        RINDENT();
                                        return XLAT_ACTION_FAIL;
                                }
                                RINDENT();
                        }
                        break;
                }
        }
                break;
 
        case XLAT_GROUP:
        {
                fr_value_box_t  *arg;
 
                /*
                 *      We'd like to do indent / exdent for groups, but that also involves fixing all of the
                 *      error paths.  Which we won't do right now.
                 */
                XLAT_DEBUG("** [%i] %s(child) - continuing %%{%s ...}", unlang_interpret_stack_depth(request), __FUNCTION__,
                           node->fmt);
 
                MEM(arg = fr_value_box_alloc(ctx, FR_TYPE_GROUP, NULL));
 
                if (!fr_value_box_list_empty(result)) {
                        VALUE_BOX_LIST_VERIFY(result);
                        fr_value_box_list_move(&arg->vb_group, result);
                }
 
//              xlat_debug_log_expansion(request, *in, NULL, __LINE__);
//              xlat_debug_log_result(request, *in, arg);
 
                VALUE_BOX_VERIFY(arg);
 
                fr_dcursor_insert(out, arg);
        }
                break;
 
        case XLAT_TMPL:
                fr_assert(tmpl_is_exec(node->vpt));
 
                if (tmpl_eval_cast_in_place(result, request, node->vpt) < 0) {
                        fr_value_box_list_talloc_free(result);
                        return XLAT_ACTION_FAIL;
                }
 
                /*
                 *      First entry is the command to run.  Subsequent entries are the options to pass to the
                 *      command.
                 */
                fr_value_box_list_move((fr_value_box_list_t *)out->dlist, result);
                break;
 
        default:
                fr_assert(0);
                return XLAT_ACTION_FAIL;
        }
 
        /*
         *      It's easier if we get xlat_frame_eval to continue evaluating the frame.
         */
        *in = xlat_exp_next(head, *in); /* advance */
        return xlat_frame_eval(ctx, out, child, request, head, in);
}
 
/** Converts xlat nodes to value boxes
 *
 * Evaluates a single level of expansions.
 *
 * @param[in] ctx               to allocate value boxes in.
 * @param[out] out              a list of #fr_value_box_t to append to.
 * @param[out] child            to evaluate.  If a child needs to be evaluated
 *                              by the caller, we return XLAT_ACTION_PUSH_CHILD
 *                              and place the child to be evaluated here.
 *                              Once evaluation is complete, the caller
 *                              should call us with the same #xlat_exp_t and the
 *                              result of the nested evaluation in result.
 * @param[in] request           the current request.
 * @param[in] head              of the list to evaluate
 * @param[in,out] in            xlat node to evaluate.  Advanced as we process
 *                              additional #xlat_exp_t.
 * @return
 *      - XLAT_ACTION_PUSH_CHILD if we need to evaluate a deeper level of nested.
 *        child will be filled with the node that needs to be evaluated.
 *        call #xlat_frame_eval_repeat on this node, once there are results
 *        from the nested expansion.
 *      - XLAT_ACTION_YIELD a resumption frame was pushed onto the stack by an
 *        xlat function and we need to wait for the request to be resumed
 *        before continuing.
 *      - XLAT_ACTION_DONE we're done, pop the frame.
 *      - XLAT_ACTION_FAIL an xlat module failed.
 */
xlat_action_t xlat_frame_eval(TALLOC_CTX *ctx, fr_dcursor_t *out, xlat_exp_head_t const **child,
                              request_t *request, xlat_exp_head_t const *head, xlat_exp_t const **in)
{
        xlat_action_t           xa = XLAT_ACTION_DONE;
        xlat_exp_t const        *node;
        fr_value_box_list_t     result;         /* tmp list so debug works correctly */
        fr_value_box_t          *value;
 
        fr_value_box_list_init(&result);
 
        *child = NULL;
 
        if (!*in) return XLAT_ACTION_DONE;
 
        XLAT_DEBUG("** [%i] %s >> entered", unlang_interpret_stack_depth(request), __FUNCTION__);
 
        for (node = *in; node; node = xlat_exp_next(head, node)) {
                *in = node;             /* Update node in our caller */
                fr_dcursor_tail(out);   /* Needed for debugging */
                VALUE_BOX_LIST_VERIFY((fr_value_box_list_t *)out->dlist);
 
                fr_assert(fr_value_box_list_num_elements(&result) == 0);        /* Should all have been moved */
 
                switch (node->type) {
                case XLAT_BOX:
                        XLAT_DEBUG("** [%i] %s(value_box) - %s", unlang_interpret_stack_depth(request), __FUNCTION__, node->fmt);
 
                        /*
                         *      Empty boxes are only allowed if
                         *      they're the only node in the expansion.
                         *
                         *      If they're found anywhere else the xlat
                         *      parser has an error.
                         */
                        fr_assert(((node == *in) && !xlat_exp_next(head, node)) || (talloc_array_length(node->fmt) > 1));
 
                        /*
                         *      We unfortunately need to dup the buffer
                         *      because references aren't threadsafe.
                         */
                        MEM(value = fr_value_box_alloc_null(ctx));
                        if (fr_value_box_copy(value, value, &node->data) < 0) goto fail;
                        fr_dcursor_append(out, value);
                        continue;
 
                case XLAT_ONE_LETTER:
                        XLAT_DEBUG("** [%i] %s(one-letter) - %%%s", unlang_interpret_stack_depth(request), __FUNCTION__,
                                   node->fmt);
 
                        xlat_debug_log_expansion(request, node, NULL, __LINE__);
                        if (xlat_eval_one_letter(ctx, &result, request, node->fmt[0]) == XLAT_ACTION_FAIL) {
                        fail:
                                fr_value_box_list_talloc_free(&result);
                                xa = XLAT_ACTION_FAIL;
                                goto finish;
                        }
                        xlat_debug_log_list_result(request, *in, &result);
                        fr_value_box_list_move((fr_value_box_list_t *)out->dlist, &result);
                        continue;
 
                case XLAT_TMPL:
                        /*
                         *      Everything should have been resolved.
                         */
                        fr_assert(!tmpl_needs_resolving(node->vpt));
 
                        if (tmpl_is_data(node->vpt)) {
                                XLAT_DEBUG("** [%i] %s(value) - %s", unlang_interpret_stack_depth(request), __FUNCTION__,
                                           node->vpt->name);
 
                                MEM(value = fr_value_box_alloc(ctx, tmpl_value_type(node->vpt), NULL));
 
                                fr_value_box_copy(value, value, tmpl_value(node->vpt)); /* Also dups taint */
                                fr_value_box_list_insert_tail(&result, value);
 
                                /*
                                 *      Cast the results if necessary.
                                 */
                                if (tmpl_eval_cast_in_place(&result, request, node->vpt) < 0) goto fail;
 
                                fr_value_box_list_move((fr_value_box_list_t *)out->dlist, &result);
                                continue;
 
                        } else if (tmpl_is_attr(node->vpt)) {
                                if (node->fmt[0] == '&') {
                                        XLAT_DEBUG("** [%i] %s(attribute) - %s", unlang_interpret_stack_depth(request), __FUNCTION__,
                                                   node->fmt);
                                } else {
                                        XLAT_DEBUG("** [%i] %s(attribute) - %%{%s}", unlang_interpret_stack_depth(request), __FUNCTION__,
                                                   node->fmt);
                                }
                                xlat_debug_log_expansion(request, node, NULL, __LINE__);
 
                                if (tmpl_eval_pair(ctx, &result, request, node->vpt) < 0) goto fail;
 
                        } else if (tmpl_is_exec(node->vpt) || tmpl_is_xlat(node->vpt)) {
                                xlat_exec_rctx_t *rctx;
 
                                /*
                                 *      Allocate and initialize the output context, with value-boxes, exec status, etc.
                                 */
                                MEM(rctx = talloc_zero(unlang_interpret_frame_talloc_ctx(request), xlat_exec_rctx_t));
                                fr_value_box_list_init(&rctx->list);
 
                                xlat_debug_log_expansion(request, node, NULL, __LINE__);
 
                                if (unlang_xlat_yield(request, xlat_exec_resume, NULL, 0, rctx) != XLAT_ACTION_YIELD) goto fail;
 
                                if (unlang_tmpl_push(ctx, &rctx->list, request, node->vpt,
                                                     TMPL_ARGS_EXEC(NULL, fr_time_delta_from_sec(EXEC_TIMEOUT),
                                                                    false, &rctx->status)) < 0) goto fail;
 
                                xa = XLAT_ACTION_PUSH_UNLANG;
                                goto finish;
 
                        } else {
#ifdef NDEBUG
                                xa = XLAT_ACTION_FAIL;
                                goto finish;
#endif
 
                                /*
                                 *      Either this should have been handled previously, or we need to write
                                 *      code to deal with this case.
                                 */
                                fr_assert(0);
                        }
 
                        xlat_debug_log_list_result(request, node, &result);
                        fr_value_box_list_move((fr_value_box_list_t *)out->dlist, &result);
                        continue;
 
                case XLAT_FUNC:
                        XLAT_DEBUG("** [%i] %s(func) - %%%s(...)", unlang_interpret_stack_depth(request), __FUNCTION__,
                                   node->fmt);
 
                        /*
                         *      Hand back the child node to the caller
                         *      for evaluation.
                         */
                        if (xlat_exp_head(node->call.args)) {
                                *child = node->call.args;
                                xa = XLAT_ACTION_PUSH_CHILD;
                                goto finish;
                        }
 
                        /*
                         *      If there's no children we can just
                         *      call the function directly.
                         */
                        xa = xlat_frame_eval_repeat(ctx, out, child, request, head, in, NULL, &result);
                        if (xa != XLAT_ACTION_DONE || (!*in)) goto finish;
                        continue;
 
#ifdef HAVE_REGEX
                case XLAT_REGEX:
                {
                        char *str = NULL;
 
                        XLAT_DEBUG("** [%i] %s(regex) - %%{%s}", unlang_interpret_stack_depth(request), __FUNCTION__,
                                   node->fmt);
 
                        xlat_debug_log_expansion(request, node, NULL, __LINE__);
                        MEM(value = fr_value_box_alloc_null(ctx));
                        if (regex_request_to_sub(ctx, &str, request, node->regex_index) < 0) {
                                talloc_free(value);
                                continue;
                        }
                        fr_value_box_bstrdup_buffer_shallow(NULL, value, NULL, str, false);
 
                        xlat_debug_log_result(request, node, value);
                        fr_dcursor_append(out, value);
                }
                        continue;
#endif
 
                case XLAT_GROUP:
                        XLAT_DEBUG("** [%i] %s(child) - %%{%s ...}", unlang_interpret_stack_depth(request), __FUNCTION__,
                                   node->fmt);
                        if (!node->group) return XLAT_ACTION_DONE;
 
                        /*
                         *      Hand back the child node to the caller
                         *      for evaluation.
                         */
                        *child = node->group;
                        xa = XLAT_ACTION_PUSH_CHILD;
                        goto finish;
 
                /*
                 *      Should have been fixed up during pass2
                 */
                case XLAT_INVALID:
                case XLAT_FUNC_UNRESOLVED:
                        fr_assert(0);
                        return XLAT_ACTION_FAIL;
                }
        }
 
finish:
        VALUE_BOX_LIST_VERIFY((fr_value_box_list_t *)out->dlist);
        XLAT_DEBUG("** [%i] %s << %s", unlang_interpret_stack_depth(request),
                   __FUNCTION__, fr_table_str_by_value(xlat_action_table, xa, "<INVALID>"));
 
        return xa;
}
 
static ssize_t xlat_eval_sync(TALLOC_CTX *ctx, char **out, request_t *request, xlat_exp_head_t const * const head,
                              xlat_escape_legacy_t escape, void const *escape_ctx)
{
        fr_value_box_list_t     result;
        bool                    success = false;
        TALLOC_CTX              *pool = talloc_new(NULL);
        rlm_rcode_t             rcode;
        char                    *str;
 
        XLAT_DEBUG("xlat_eval_sync");
 
        *out = NULL;
 
        fr_value_box_list_init(&result);
 
        /*
         *      Use the unlang stack to evaluate the xlat.
         */
        if (unlang_xlat_push(pool, &success, &result, request, head, UNLANG_TOP_FRAME) < 0) {
        fail:
                talloc_free(pool);
                return -1;
        }
 
        /*
         *      Pure functions don't yield, and can therefore be
         *      expanded in place.  This check saves an expensive
         *      bounce through a new synchronous interpreter.
         */
        if (!xlat_impure_func(head) && unlang_interpret_get(request)) {
                rcode = unlang_interpret(request, UNLANG_REQUEST_RUNNING);
        } else {
                rcode = unlang_interpret_synchronous(unlang_interpret_event_list(request), request);
        }
 
        switch (rcode) {
        default:
                if (!success) goto fail;
                break;
 
        case RLM_MODULE_REJECT:
        case RLM_MODULE_FAIL:
                goto fail;
        }
 
        if (!fr_value_box_list_empty(&result)) {
                if (escape) {
                        fr_value_box_t *vb = NULL;
 
                        /*
                         *      For tainted boxes perform the requested escaping
                         */
                        while ((vb = fr_value_box_list_next(&result, vb))) {
                                fr_value_box_entry_t entry;
                                size_t len, real_len;
                                char *escaped;
 
                                if (!vb->tainted) continue;
 
                                if (fr_value_box_cast_in_place(pool, vb, FR_TYPE_STRING, NULL) < 0) {
                                        RPEDEBUG("Failed casting result to string");
                                        goto fail;
                                }
 
                                len = vb->vb_length * 3;
                                MEM(escaped = talloc_array(pool, char, len));
                                real_len = escape(request, escaped, len, vb->vb_strvalue, UNCONST(void *, escape_ctx));
 
                                entry = vb->entry;
                                fr_value_box_clear_value(vb);
                                fr_value_box_bstrndup(vb, vb, NULL, escaped, real_len, false);
                                vb->entry = entry;
 
                                talloc_free(escaped);
                        }
                }
 
                str = fr_value_box_list_aprint(ctx, &result, NULL, NULL);
                if (!str) goto fail;
        } else {
                str = talloc_typed_strdup(ctx, "");
        }
        talloc_free(pool);      /* Memory should be in new ctx */
 
        *out = str;
 
        return talloc_array_length(str) - 1;
}
 
/** Replace %whatever in a string.
 *
 * See 'doc/unlang/xlat.adoc' for more information.
 *
 * @param[in] ctx               to allocate expansion buffers in.
 * @param[out] out              Where to write pointer to output buffer.
 * @param[in] outlen            Size of out.
 * @param[in] request           current request.
 * @param[in] head              the xlat structure to expand
 * @param[in] escape            function to escape final value e.g. SQL quoting.
 * @param[in] escape_ctx        pointer to pass to escape function.
 * @return length of string written @bug should really have -1 for failure.
 */
static ssize_t _xlat_eval_compiled(TALLOC_CTX *ctx, char **out, size_t outlen, request_t *request,
                                   xlat_exp_head_t const *head, xlat_escape_legacy_t escape, void const *escape_ctx)
{
        char *buff;
        ssize_t slen;
 
        fr_assert(head != NULL);
 
        slen = xlat_eval_sync(ctx, &buff, request, head, escape, escape_ctx);
        if (slen < 0) {
                fr_assert(buff == NULL);
                if (*out) **out = '\0';
                return slen;
        }
 
        /*
         *      If out doesn't point to an existing buffer
         *      copy the pointer to our buffer over.
         */
        if (!*out) {
                *out = buff;
                return slen;
        }
 
        if ((size_t)slen >= outlen) {
                fr_strerror_const("Insufficient output buffer space");
                return -1;
        }
 
        /*
         *      Otherwise copy the talloced buffer to the fixed one.
         */
        memcpy(*out, buff, slen);
        (*out)[slen] = '\0';
        talloc_free(buff);
 
        return slen;
}
 
/** Replace %whatever in a string.
 *
 * See 'doc/unlang/xlat.adoc' for more information.
 *
 * @param[in] ctx               to allocate expansion buffers in.
 * @param[out] out              Where to write pointer to output buffer.
 * @param[in] outlen            Size of out.
 * @param[in] request           current request.
 * @param[in] fmt               string to expand.
 * @param[in] escape            function to escape final value e.g. SQL quoting.
 * @param[in] escape_ctx        pointer to pass to escape function.
 * @return length of string written @bug should really have -1 for failure.
 */
static CC_HINT(nonnull (2, 4, 5))
ssize_t _xlat_eval(TALLOC_CTX *ctx, char **out, size_t outlen, request_t *request, char const *fmt,
                   xlat_escape_legacy_t escape, void const *escape_ctx)
{
        ssize_t len;
        xlat_exp_head_t *head;
 
        RINDENT();
 
        /*
         *      Give better errors than the old code.
         */
        len = xlat_tokenize(ctx, &head,
                            &FR_SBUFF_IN(fmt, strlen(fmt)),
                            NULL,
                            &(tmpl_rules_t){
                                    .attr = {
                                            .dict_def = request->dict,
                                            .list_def = request_attr_request,
                                    },
                                    .xlat = {
                                            .runtime_el = unlang_interpret_event_list(request),
                                    },
                                    .at_runtime = true,
                            });
        if (len == 0) {
                if (*out) {
                        **out = '\0';
                } else {
                        *out = talloc_zero_array(ctx, char, 1);
                }
                REXDENT();
                return 0;
        }
 
        if (len < 0) {
                REMARKER(fmt, -(len), "%s", fr_strerror());
                if (*out) **out = '\0';
                REXDENT();
                return -1;
        }
 
        len = _xlat_eval_compiled(ctx, out, outlen, request, head, escape, escape_ctx);
        talloc_free(head);
 
        REXDENT();
 
        return len;
}
 
ssize_t xlat_eval(char *out, size_t outlen, request_t *request,
                  char const *fmt, xlat_escape_legacy_t escape, void const *escape_ctx)
{
        fr_assert(instance_count);
 
        return _xlat_eval(request, &out, outlen, request, fmt, escape, escape_ctx);
}
 
ssize_t xlat_eval_compiled(char *out, size_t outlen, request_t *request,
                           xlat_exp_head_t const *xlat, xlat_escape_legacy_t escape, void const *escape_ctx)
{
        fr_assert(instance_count);
 
        return _xlat_eval_compiled(request, &out, outlen, request, xlat, escape, escape_ctx);
}
 
ssize_t xlat_aeval(TALLOC_CTX *ctx, char **out, request_t *request, char const *fmt,
                   xlat_escape_legacy_t escape, void const *escape_ctx)
{
        fr_assert(instance_count);
 
        *out = NULL;
        return _xlat_eval(ctx, out, 0, request, fmt, escape, escape_ctx);
}
 
ssize_t xlat_aeval_compiled(TALLOC_CTX *ctx, char **out, request_t *request,
                            xlat_exp_head_t const *xlat, xlat_escape_legacy_t escape, void const *escape_ctx)
{
        fr_assert(instance_count);
 
        *out = NULL;
        return _xlat_eval_compiled(ctx, out, 0, request, xlat, escape, escape_ctx);
}
 
 
/** Turn am xlat list into an argv[] array, and nuke the input list.
 *
 *  This is mostly for async use.
 */
int xlat_flatten_to_argv(TALLOC_CTX *ctx, xlat_exp_head_t ***argv, xlat_exp_head_t *head)
{
        int                     i;
        xlat_exp_head_t         **my_argv;
        size_t                  count;
 
        if (head->flags.needs_resolving) {
                fr_strerror_printf("Cannot flatten expression with unresolved functions");
                return -1;
        }
 
        count = 0;
        xlat_exp_foreach(head, node) {
                count++;
        }
 
        MEM(my_argv = talloc_zero_array(ctx, xlat_exp_head_t *, count + 1));
        *argv = my_argv;
 
        fr_assert(instance_count);
 
        i = 0;
        xlat_exp_foreach(head, node) {
                fr_assert(node->type == XLAT_GROUP);
                my_argv[i++] = talloc_steal(my_argv, node->group);
        }
 
        fr_value_box_list_talloc_free((fr_value_box_list_t *)&head->dlist);
 
        return count;
}
 
/** Walk over all xlat nodes (depth first) in a xlat expansion, calling a callback
 *
 * @param[in] head      to evaluate.
 * @param[in] walker    callback to pass nodes to.
 * @param[in] type      if > 0 a mask of types to call walker for.
 * @param[in] uctx      to pass to walker.
 * @return
 *      - 0 on success (walker always returned 0).
 *      - <0 if walker returned <0.
 */
int xlat_eval_walk(xlat_exp_head_t *head, xlat_walker_t walker, xlat_type_t type, void *uctx)
{
        int             ret;
 
        /*
         *      Iterate over nodes at the same depth
         */
        xlat_exp_foreach(head, node) {
                switch (node->type){
                case XLAT_FUNC:
                        /*
                         *      Evaluate the function's arguments
                         *      first, as they may get moved around
                         *      when the function is instantiated.
                         */
                        if (xlat_exp_head(node->call.args)) {
                                ret = xlat_eval_walk(node->call.args, walker, type, uctx);
                                if (ret < 0) return ret;
                        }
 
                        if (!type || (type & XLAT_FUNC)) {
                                ret = walker(node, uctx);
                                if (ret < 0) return ret;
                        }
                        break;
 
                case XLAT_FUNC_UNRESOLVED:
                        if (xlat_exp_head(node->call.args)) {
                                ret = xlat_eval_walk(node->call.args, walker, type, uctx);
                                if (ret < 0) return ret;
                        }
 
                        if (!type || (type & XLAT_FUNC_UNRESOLVED)) {
                                ret = walker(node, uctx);
                                if (ret < 0) return ret;
                        }
                        break;
 
                case XLAT_GROUP:
                        if (!type || (type & XLAT_GROUP)) {
                                ret = walker(node, uctx);
                                if (ret < 0) return ret;
                                if (ret > 0) continue;
                        }
 
                        /*
                         *      Evaluate the child.
                         */
                        ret = xlat_eval_walk(node->group, walker, type, uctx);
                        if (ret < 0) return ret;
                        break;
 
                default:
                        if (!type || (type & node->type)) {
                                ret = walker(node, uctx);
                                if (ret < 0) return ret;
                        }
                        break;
                }
        }
 
        return 0;
}
 
int xlat_eval_init(void)
{
        fr_assert(!instance_count);
 
        if (instance_count > 0) {
                instance_count++;
                return 0;
        }
 
        instance_count++;
 
        if (fr_dict_autoload(xlat_eval_dict) < 0) {
                PERROR("%s", __FUNCTION__);
                return -1;
        }
 
        if (fr_dict_attr_autoload(xlat_eval_dict_attr) < 0) {
                PERROR("%s", __FUNCTION__);
                fr_dict_autofree(xlat_eval_dict);
                return -1;
        }
 
        return 0;
}
 
void xlat_eval_free(void)
{
        fr_assert(instance_count > 0);
 
        if (--instance_count > 0) return;
 
        fr_dict_autofree(xlat_eval_dict);
}