pair_legacy.c

Go to the documentation of this file.

/*
 *   This library is free software; you can redistribute it and/or
 *   modify it under the terms of the GNU Lesser General Public
 *   License as published by the Free Software Foundation; either
 *   version 2.1 of the License, or (at your option) any later version.
 *
 *   This library 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
 *   Lesser General Public License for more details.
 *
 *   You should have received a copy of the GNU Lesser General Public
 *   License along with this library; if not, write to the Free Software
 *   Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301, USA
 */
 
/** AVP manipulation and search API
 *
 * @file src/lib/util/pair_legacy.c
 *
 * @copyright 2000,2006,2015 The FreeRADIUS server project
 */
RCSID("$Id: 6102cb99d02877e9d76367286263a166f018ceb9 $")
 
#include <sys/wait.h>
 
#include <freeradius-devel/util/dict.h>
#include <freeradius-devel/util/pair.h>
#include <freeradius-devel/util/pair_legacy.h>
#include <freeradius-devel/util/proto.h>
#include <freeradius-devel/util/regex.h>
#include <freeradius-devel/util/syserror.h>
 
#include <freeradius-devel/protocol/radius/rfc2865.h>
#include <freeradius-devel/protocol/freeradius/freeradius.internal.h>
 
static fr_sbuff_term_t const    bareword_terminals =
                                FR_SBUFF_TERMS(
                                        L("\t"),
                                        L("\n"),
                                        L(" "),
                                        L("!*"),
                                        L("!="),
                                        L("!~"),
                                        L("&&"),                /* Logical operator */
                                        L(")"),                 /* Close condition/sub-condition */
                                        L("+="),
                                        L("-="),
                                        L(":="),
                                        L("<"),
                                        L("<="),
                                        L("=*"),
                                        L("=="),
                                        L("=~"),
                                        L(">"),
                                        L(">="),
                                        L("||"),                /* Logical operator */
                                );
 
static fr_table_num_sorted_t const pair_assignment_op_table[] = {
        { L("+="),      T_OP_ADD_EQ             },
        { L(":="),      T_OP_SET                },
        { L("="),       T_OP_EQ                 },
};
static ssize_t pair_assignment_op_table_len = NUM_ELEMENTS(pair_assignment_op_table);
 
static fr_table_num_sorted_t const pair_comparison_op_table[] = {
        { L("!*"),      T_OP_CMP_FALSE          },
        { L("!="),      T_OP_NE                 },
        { L("!~"),      T_OP_REG_NE             },
        { L("+="),      T_OP_ADD_EQ             },
        { L(":="),      T_OP_SET                },
        { L("<"),       T_OP_LT                 },
        { L("<="),      T_OP_LE                 },
        { L("="),       T_OP_EQ                 },
        { L("=*"),      T_OP_CMP_TRUE           },
        { L("=="),      T_OP_CMP_EQ             },
        { L("=~"),      T_OP_REG_EQ             },
        { L(">"),       T_OP_GT                 },
        { L(">="),      T_OP_GE                 }
};
static size_t pair_comparison_op_table_len = NUM_ELEMENTS(pair_comparison_op_table);
 
/*
 *      Stop parsing bare words at whitespace, comma, or end of list.
 *
 *      Note that we don't allow escaping of bare words here, as that screws up parsing of raw attributes with
 *      0x... prefixes.
 */
static fr_sbuff_parse_rules_t const bareword_unquoted = {
        .terminals = &FR_SBUFF_TERMS(
                L(""),
                L("\t"),
                L("\n"),
                L("\r"),
                L(" "),
                L(","),
                L("}")
        )
};
 
 
static fr_slen_t fr_pair_value_from_substr(fr_pair_parse_t const *conf, fr_pair_t *vp, fr_sbuff_t *in)
{
        fr_sbuff_t                      our_in = FR_SBUFF(in);
        char                            quote;
        fr_slen_t                       slen;
        fr_sbuff_parse_rules_t const    *rules;
 
        if (fr_sbuff_next_if_char(&our_in, '"')) {
                rules = &value_parse_rules_double_quoted;
                quote = '"';
        parse:
                slen = fr_value_box_from_substr(vp, &vp->data, vp->da->type, vp->da, &our_in, rules);
        } else if (fr_sbuff_next_if_char(&our_in, '\'')) {
                rules = &value_parse_rules_single_quoted;
                quote = '\'';
                goto parse;
        } else if (!fr_sbuff_next_if_char(&our_in, '`')) {
                quote = '\0';
                rules = &bareword_unquoted;
                goto parse;
        /*
         *      We _sometimes_ support backticks, depending on the
         *      source of the data.  This should ONLY be used on
         *      trusted input, like config files.
         *
         *      We don't impose arbitrary limits on exec input or
         *      output, as AGAIN this should only be used on trusted
         *      input.
         *
         *      Only the first line of output from the process is used,
         *      and no escape sequences in the output are processed.
         */
        } else {
                fr_sbuff_t              *exec_in;
                size_t                  exec_out_buff_len = 0;
                ssize_t                 exec_out_len;
                char                    *exec_out = NULL;
                FILE                    *fp;
                int                     ret;
 
                if (!conf->allow_exec) {
                        fr_strerror_const("Backticks are not supported here");
                        return 0;
                }
 
                /*
                 *      Should only be used for trusted resources, so no artificial limits
                 */
                FR_SBUFF_TALLOC_THREAD_LOCAL(&exec_in, 1024, SIZE_MAX);
                if (fr_sbuff_out_unescape_until(NULL, exec_in, &our_in, SIZE_MAX,
                                                &FR_SBUFF_TERMS(L("`")), &fr_value_unescape_backtick) < 0) {
                        fr_strerror_const("Failed reading backtick string");
                        return 0;
                }
                /*
                 *      Don't exec if we know we're going to fail
                 */
                if (!fr_sbuff_is_char(&our_in, '`')) {
                        fr_strerror_const("Unterminated backtick string");
                        return 0;
                }
 
                fp = popen(fr_sbuff_start(exec_in), "r");
                if (!fp) {
                        fr_strerror_printf("Cannot execute command `%pV`: %s",
                                           fr_box_strvalue_len(fr_sbuff_start(exec_in), fr_sbuff_used(exec_in)),
                                           fr_syserror(errno));
                        return 0;
                }
 
                errno = 0; /* If we get EOF immediately, we don't want to emit spurious errors */
                exec_out_len = getline(&exec_out, &exec_out_buff_len, fp);
                if ((exec_out_len < 0) || (exec_out == NULL)) { /* defensive */
                        fr_strerror_printf("Cannot read output from command `%pV`: %s",
                                           fr_box_strvalue_len(fr_sbuff_start(exec_in), fr_sbuff_used(exec_in)),
                                           fr_syserror(errno));
                        pclose(fp);
                        return 0;
                }
 
                /*
                 *      Protect against child writing too much data to stdout,
                 *      blocking, and never exiting.
                 *
                 *      This is likely overly cautious for this particular use
                 *      case, but it doesn't hurt.
                 */
                {
                        char buffer[128];
 
                        while (fread(buffer, 1, sizeof(buffer), fp) > 0) { /* discard */ }
                }
 
                errno = 0;      /* ensure we don't have stale errno */
                ret = pclose(fp);
                if (ret < 0) {
                        fr_strerror_printf("Error waiting for command `%pV` to finish: %s",
                                           fr_box_strvalue_len(fr_sbuff_start(exec_in), fr_sbuff_used(exec_in)),
                                           fr_syserror(errno));
                pclose_error:
                        free(exec_out);
                        return 0;
                } else if (ret != 0) {
                        if (WIFEXITED(ret)) {
                                fr_strerror_printf("Command `%pV` exited with status %d",
                                                  fr_box_strvalue_len(fr_sbuff_start(exec_in), fr_sbuff_used(exec_in)),
                                                  WEXITSTATUS(ret));
                        } else if (WIFSIGNALED(ret)) {
                                fr_strerror_printf("Command `%pV` terminated by signal %d",
                                                   fr_box_strvalue_len(fr_sbuff_start(exec_in), fr_sbuff_used(exec_in)),
                                                   WTERMSIG(ret));
                        } else {
                                fr_strerror_printf("Command `%pV` terminated abnormally",
                                                   fr_box_strvalue_len(fr_sbuff_start(exec_in), fr_sbuff_used(exec_in)));
                        }
                        goto pclose_error;
                }
 
                /*
                 *      Trim line endings
                 */
                if (exec_out_len > 0 && exec_out[exec_out_len - 1] == '\n') exec_out[--exec_out_len] = '\0';
                if (exec_out_len > 0 && exec_out[exec_out_len - 1] == '\r') exec_out[--exec_out_len] = '\0';
 
                slen = fr_value_box_from_substr(vp, &vp->data, vp->da->type, vp->da,
                                                &FR_SBUFF_IN(exec_out, exec_out_len), &value_parse_rules_single_quoted);
                free(exec_out);
                if (unlikely(slen < 0)) {
                        return 0; /* slen is parse position in the exec output*/
                }
 
                quote = '`';
        }
 
        if (slen < 0) {
                fr_assert(slen >= -((ssize_t) 1 << 20));
                return slen - (quote != 0);
        }
 
        if (quote && !fr_sbuff_next_if_char(&our_in, quote)) {
                fr_strerror_const("Unterminated string");
                return 0;
        }
 
        fr_assert(slen <= ((ssize_t) 1 << 20));
 
        FR_SBUFF_SET_RETURN(in, &our_in);
}
 
/** Our version of a DA stack.
 *
 *      @todo - add in whether or not we added / created the vp?  maybe an edit list?
 *      and then we can clean up the unknown DAs, simply by talloc freeing the edit list.
 */
typedef struct {
        int depth;
        fr_dict_attr_t const    *da[FR_DICT_MAX_TLV_STACK];     //!< parent for parsing
        fr_pair_t               *vp[FR_DICT_MAX_TLV_STACK];     //!< which VP we have created or found
} legacy_da_stack_t;
 
/**  Parse a #fr_pair_list_t from a substring
 *
 *      Syntax: ([raw.]|.)<name>[<.name>] op [(cast)] value...
 *
 *      A "raw" prefix creates a raw attribute, which allows us to encode raw data which might be invalid for
 *      the given data type.  Or if a "(cast)" is given, the value is parsed as the specified data type.  Note
 *      that casts can only be to a "leaf" data type, and not to a structural type such as "tlv", "group",
 *      "struct", etc.  The "(cast)" syntax can only be used for "raw" attributes, and not for attributes
 *      which are known.  The "name" can be either a known attribute, or a numerical OID.  Either way, the
 *      final attribute which is created is marked as "raw" or "unknown", and is encoded via the "raw" rules,
 *      and not as the known data type.
 *
 *      If the first name begins with ".", then it is a _relative_ name.  The attribute is created in the
 *      context of the most recently created "structural" data type.
 *
 *      TBD - we have to determine what the heck that means...
 *
 *      The "name" can be one or more names from the input dictionary.  The names must be known, as numerical
 *      OIDs can only be used when the "raw" prefix is used.
 *
 *      If there are multiple names (e.g. "foo.bar.baz"), then only the last name can be a "leaf" data
 *      type.  All of the intermediate names must be "structural" data types.
 *
 *      Depending on the input arguments, the operator can be a comparison operator (==, <=, etc.).  Or, else
 *      it can be an assignment operator (=, +=).  The "=" operator is used to assign, and the "+=" operator
 *      is used to append.  No other assignment operators are permitted.  Note that "+=" cannot be used with
 *      relative names (i.e. where the name begins with ".")
 *
 *      The "value" can either be a "leaf" data type (e.g. number, IP address, etc.) or for "structural" data
 *      types it can be a sub-list.  A sub-list is a set of attribute assignments which are surrounded by
 *      curly brackets "{...}".  When a sub-list is specified, the contents must be either children of the
 *      parent attribute (for "tlv", "struct"), or children referenced by a "group", or internal attributes.
 *
 *      If an intermediate "name" is an ALIAS, then the attributes are created / used as if all intermediate
 *      names were specified.  i.e. ALIAS is a short-cut for names (think "soft link), but it does not change
 *      the hierarchy for normal attributes.
 *
 *
 *      Examples
 *      --------
 *
 *      Name = value
 *              Leaf attributes.
 *              The value MUST be parsed as the leaf data type.
 *
 *      Name = { children }
 *              Structural attributes.
 *              The children MUST be children of the parent.
 *              OR the children can be from the "internal" dictionary.
 *              OR for type 'group', children of the group reference (usually the dictionary root)
 *
 *      raw.Name = 0xabcdef
 *              Raw attributes.
 *              The value MUST be a hex string.
 *
 *      raw.Name = { children }
 *
 * @param[in] root      where we start parsing from
 * @param[in,out] relative where we left off, or where we should continue from
 * @param[in] in        input sbuff
 * @return
 *      - <0 on error
 *      - 0 on no input
 *      - >0 on how many bytes of input we read
 */
fr_slen_t fr_pair_list_afrom_substr(fr_pair_parse_t const *root, fr_pair_parse_t *relative,
                                    fr_sbuff_t *in)
{
        int                     i, components;
        bool                    raw, was_unknown;
        bool                    was_relative = false;
        bool                    append;
        bool                    keep_going;
        fr_type_t               raw_type;
        fr_token_t              op;
        fr_slen_t               slen;
        fr_pair_t               *vp;
        fr_pair_parse_t         my;
        fr_sbuff_marker_t       lhs_m, op_m, rhs_m;
        fr_sbuff_t              our_in = FR_SBUFF(in);
        legacy_da_stack_t       da_stack = {};
 
        if (unlikely(!root->ctx)) {
                fr_strerror_const("Missing input context (fr_pair_parse_t)");
                return -1;
        }
 
        if (unlikely(!root->da)) {
                fr_strerror_const("Missing namespace attribute");
                return -1;
        }
 
        if (unlikely(!root->list)) {
                fr_strerror_const("Missing list");
                return -1;
        }
 
        fr_sbuff_adv_past_blank(&our_in, SIZE_MAX, NULL);
 
        if (fr_sbuff_remaining(&our_in) == 0) return 0;
 
        /*
         *      Boot strap the relative references from the root.
         *
         *      The comparison operations are only used for internal tests, and should not be used by
         *      administrators.  So we disallow them, unless the destination list is empty.  This check
         *      prevents them from being used in administrative policies.
         */
        if (!relative->da) {
                if (root->allow_compare && !fr_pair_list_empty(root->list)) {
                        fr_strerror_const("Attribute comparisons can only be used when the destination list is empty");
                        return -1;
                }
 
                *relative = *root;
        }
 
#define CLEAN_DA_STACK do { if (was_unknown) {          \
        for (i = 1; i < da_stack.depth; i++) {          \
                fr_dict_attr_unknown_free(&da_stack.da[i]); \
        } } } while (0)
 
        /*
         *      Initialize the markers once, before the redo label, so that they are only inserted into the
         *      marker linked list once.  After this, use fr_sbuff_set() to update marker positions.
         */
        fr_sbuff_marker(&lhs_m, &our_in);
        fr_sbuff_marker(&op_m, &our_in);
        fr_sbuff_marker(&rhs_m, &our_in);
 
redo:
        raw = false;
        raw_type = FR_TYPE_NULL;
        relative->last_char = 0;
        was_unknown = false;
        vp = NULL;
 
        fr_sbuff_adv_past_blank(&our_in, SIZE_MAX, NULL);
 
        /*
         *      STEP 1: Figure out if we have relative or absolute attributes.
         *
         *      Absolute attributes start from the root list / parent.
         *      Or, when there is no previous relative setting.
         *
         *      Relative attributes start from the input list / parent.
         *
         *      Once we decide where we start parsing from, all subsequent operations are on the "relative"
         *      structure.
         */
        if (!fr_sbuff_next_if_char(&our_in, '.')) {
                *relative = *root;
 
                append = !was_relative;
                was_relative = false;
 
                /*
                 *      Be nice to people who expect to use '&' everywhere.
                 */
                (void) fr_sbuff_next_if_char(&our_in, '&');
 
                /*
                 *      Raw attributes can only be at our root.
                 *
                 *      "raw.foo" means that SOME component of the OID is raw.  But the starting bits might be known.
                 *
                 *      Raw attributes cannot be created in the internal namespace.  But an internal group can
                 *      contain raw protocol attributes.
                 */
                if (fr_sbuff_is_str_literal(&our_in, "raw.")) {
                        fr_sbuff_advance(&our_in, 4);
                        goto is_raw;
                }
 
        } else if (relative->da->flags.is_root) {
                fr_strerror_const("The '.Attribute' syntax cannot be used at the root of a dictionary");
 
        error:
                CLEAN_DA_STACK;
                return fr_sbuff_error(&our_in);
 
        } else if (relative->da->type == FR_TYPE_GROUP) {
                fr_strerror_printf("The '.Attribute' syntax cannot be used with parent %s of data type 'group'",
                                   relative->da->name);
                goto error;
 
        } else {
                fr_assert(relative->ctx);
                fr_assert(relative->list);
 
                was_relative = true;
                append = true;
        }
 
        /*
         *      If the input root is an unknown attribute, then forbid internal ones, and force everything
         *      else to be raw, too.
         */
        if (relative->da->flags.is_unknown) {
        is_raw:
                raw = true;
        }
 
        /*
         *      Raw internal attributes don't make sense.  An internal group can contain raw protocol
         *      attributes, but the group is not raw.
         */
        if (raw && relative->da->flags.internal) {
                fr_strerror_const("Cannot create internal attributes which are 'raw'");
                goto error;
        }
 
        /*
         *      Set the LHS marker to be after any initial '.'
         */
        fr_sbuff_set(&lhs_m, &our_in);
 
        /*
         *      STEP 2: Find and check the operator.
         *
         *      Skip over the attribute name.  We need to get the operator _before_ creating the VPs.
         */
        components = 0;
        do {
                if (fr_sbuff_adv_past_allowed(&our_in, SIZE_MAX, fr_dict_attr_allowed_chars, NULL) == 0) break;
                components++;
        } while (fr_sbuff_next_if_char(&our_in, '.'));
 
        /*
         *      Couldn't find anything.
         */
        if (!components) goto done;
 
        fr_sbuff_set(&op_m, &our_in);
        fr_sbuff_adv_past_blank(&our_in, SIZE_MAX, NULL);
 
        /*
         *      Look for the operator.
         */
        if (relative->allow_compare) {
                fr_sbuff_out_by_longest_prefix(&slen, &op, pair_comparison_op_table, &our_in, T_INVALID);
                if (op == T_INVALID) {
                        fr_strerror_const("Expecting operator");
                        goto error;
                }
 
                /*
                 *      People can use this, but it doesn't mean anything.
                 */
                if (op == T_OP_SET) op = T_OP_EQ;
 
        } else {
                /*
                 *      @todo - handle different operators ala v3?
                 *      What is the difference between ":=" and "="?  Perhaps nothing?
                 */
                fr_sbuff_out_by_longest_prefix(&slen, &op, pair_assignment_op_table, &our_in, T_INVALID);
                if (op == T_INVALID) {
                        fr_strerror_const("Expecting operator");
                        goto error;
                }
 
                /*
                 *      += means "append"
                 *      := menas "don't append".
                 */
                if (op != T_OP_EQ) {
                        if (was_relative) {
                                fr_strerror_printf("The '.Attribute' syntax cannot be used along with the '%s' operator",
                                                   fr_tokens[op]);
                                goto error;
                        }
                }
 
                if (op == T_OP_ADD_EQ) {
                        append = true;
                }
 
                if (op == T_OP_SET) {
                        append = false;
                }
 
                op = T_OP_EQ;
        }
 
        /*
         *      Check the character after the operator.  This check is only necessary to produce better error
         *      messages.  i.e. We allow "=", but the user enters "==".
         */
        {
                uint8_t c = fr_sbuff_uint8(&our_in, '\0');
                static const bool invalid[SBUFF_CHAR_CLASS] = {
                        ['!'] = true, ['#'] = true, ['$'] = true, ['*'] = true,
                        ['+'] = true, ['-'] = true, ['/'] = true, ['<'] = true,
                        ['='] = true, ['>'] = true, ['?'] = true, ['|'] = true,
                        ['~'] = true,
                };
 
                if (c && invalid[c]) {
                        fr_strerror_printf("Invalid character '%c' after operator '%s'",
                                           (char) c, fr_tokens[op]);
                        goto error;
                }
        }
 
        /*
         *      Skip past whitespace, and set a marker at the RHS value.  We do a quick peek at the value, to
         *      set the data type of the RHS.  This allows us to parse raw TLVs.
         */
        fr_sbuff_adv_past_blank(&our_in, SIZE_MAX, NULL);
 
        /*
         *      STEP 3: Try to guess the data type for "raw" attributes.
         *
         *      If the attribute is raw, and the value of the attribute is 0x..., then we always force the raw
         *      type to be octets, even if the attribute is named and known.  e.g. raw.Framed-IP-Address =
         *      0x01.
         *
         *      OR if the attribute is entirely unknown (and not a raw version of a known one), then we allow a
         *      cast which sets the data type.
         */
        if (raw) {
                if (fr_sbuff_is_str_literal(&our_in, "0x")) {
                        raw_type = FR_TYPE_OCTETS;
 
                } else if (fr_sbuff_next_if_char(&our_in, '(')) {
                        fr_sbuff_marker_t cast_m;
 
                        fr_sbuff_marker(&cast_m, &our_in);
 
                        fr_sbuff_out_by_longest_prefix(&slen, &raw_type, fr_type_table, &our_in, FR_TYPE_NULL);
 
                        /*
                         *      The input has to be a real (non-NULL) leaf.  The input shouldn't be cast to a
                         *      TLV.  Instead, the value should just start with '{'.
                         */
                        if (!fr_type_is_leaf(raw_type)) {
                                fr_sbuff_set(&our_in, &cast_m);
                                fr_strerror_const("Invalid data type in cast");
                                goto error;
                        }
 
                        if (!fr_sbuff_next_if_char(&our_in, ')')) {
                                fr_strerror_const("Missing ')' in cast");
                                goto error;
                        }
 
                        fr_sbuff_adv_past_blank(&our_in, SIZE_MAX, NULL);
 
                } else if (fr_sbuff_is_char(&our_in, '{')) {
                        /*
                         *      Raw attributes default to data type TLV.
                         */
                        raw_type = FR_TYPE_TLV;
                        append = false;
                }
        }
 
        fr_sbuff_set(&rhs_m, &our_in);
 
        fr_sbuff_set(&our_in, &lhs_m);
 
        /*
         *      That we know the data type, parse each OID component.  We build the DA stack from top to bottom.
         *
         *      0 is our relative root.  1..N are the DAs that we find or create.
         */
        da_stack = (legacy_da_stack_t) {
                .da = {
                        [0] = relative->da,
                },
                .depth = 1,
        };
 
        /*
         *      STEP 4: Re-parse the attributes, building up the da_stack of #fr_dict_attr_t that we will be
         *      using as parents.
         */
        for (i = 1; i <= components; i++, da_stack.depth++) {
                fr_dict_attr_err_t      err;
                fr_dict_attr_t const    *da = NULL;
                fr_dict_attr_t const    *da_unknown = NULL;
                fr_dict_attr_t const    *parent;
                fr_dict_attr_t const    *ref;
                fr_type_t               unknown_type;
 
                if (da_stack.depth >= FR_DICT_MAX_TLV_STACK) {
                        fr_strerror_printf("Attributes are nested too deeply at \"%.*s\"",
                                           (int) fr_sbuff_diff(&op_m, &lhs_m), fr_sbuff_current(&lhs_m));
                        goto error;
                }
 
                fr_sbuff_set(&lhs_m, &our_in);
 
                /*
                 *      The fr_pair_t parent might be a group, in which case the fr_dict_attr_t parent will be
                 *      different.
                 */
                parent = da_stack.da[da_stack.depth - 1];
                if (parent->type == FR_TYPE_GROUP) {
                        parent = fr_dict_attr_ref(parent);
                        fr_assert(parent != NULL);
                }
 
                /*
                 *      Once we parse a completely unknown attribute, all of the rest of them have to be
                 *      unknown, too.  We cannot allow unknown TLVs to contain internal attributes, for
                 *      example.
                 */
                if (was_unknown) {
                        goto alloc_unknown;
                }
 
                /*
                 *      Look up the name (or number).  If it's found, life is easy.  Otherwise, we jump
                 *      through a bunch of hoops to see if we are changing dictionaries, or creating a raw OID
                 *      from a number, etc.
                 */
                slen = fr_dict_oid_component(&err, &da, parent, &our_in, &bareword_terminals);
                if (err != FR_DICT_ATTR_OK) {
                        /*
                         *      We were looking in the internal dictionary.  Maybe this attribute is instead
                         *      in the protocol dictionary?
                         */
                        if ((i == 1) && (relative->da->dict == relative->internal) && relative->dict) {
                                fr_assert(relative->dict != relative->internal);
 
                                /*
                                 *      Internal groups can be used to cache protocol data.  Internal
                                 *      structural attributes cannot.
                                 *
                                 *      @todo - this restriction makes sense, but maybe people want to do that
                                 *      anyways?
                                 */
                                if (relative->da->type != FR_TYPE_GROUP) {
                                        fr_strerror_printf("Internal attribute '%s' of data type '%s' cannot contain protocol attributes",
                                                           relative->da->name, fr_type_to_str(relative->da->type));
                                        goto error;
                                }
 
                                slen = fr_dict_oid_component(&err, &da, fr_dict_root(relative->dict), &our_in, &bareword_terminals);
                                if (err == FR_DICT_ATTR_OK) {
                                        ref = fr_dict_root(relative->dict);
                                        goto found;
                                }
                        }
 
                        /*
                         *      Try to parse the name from the internal namespace first, as this is the most
                         *      likely case.  Plus, if we parse the OIDs second, the errors for unknown
                         *      attributes mention the protocol dictionary, and not the internal one.
                         *
                         *      Raw attributes also cannot be created in the internal dictionary space.
                         */
                        if (!raw && relative->internal) {
                                /*
                                 *      If the current dictionary isn't internal, then look up the attribute
                                 *      in the internal dictionary.
                                 *
                                 *      Buf if the current dictionary is internal, AND the internal type is
                                 *      GROUP, AND we we have a protocol dictionary, then allow an internal
                                 *      group to contain protocol attributes.
                                 */
                                if (parent->dict != relative->internal) {
                                        ref = fr_dict_root(relative->internal);
 
                                } else if ((da_stack.da[da_stack.depth - 1]->type == FR_TYPE_GROUP) && (root->da->dict != root->internal)) {
                                        ref = fr_dict_root(root->da->dict);
 
                                } else {
                                        /*
                                         *      Otherwise we are already in the internal dictionary, and the
                                         *      attribute was not found.  So don't search for it again in the
                                         *      internal dictionary.  And because we're in the internal
                                         *      dictionary, we don't allow raw attributes.
                                         */
                                        goto notfound;
                                }
 
                                slen = fr_dict_oid_component(&err, &da, ref, &our_in, &bareword_terminals);
                                if (err == FR_DICT_ATTR_OK) {
                                        goto found;
                                }
 
                                goto notfound;
                        }
 
                        /*
                         *      We didn't find anything, that's an error.
                         */
                        if (!raw) {
                        notfound:
                                fr_strerror_printf("Unknown attribute \"%.*s\" for parent \"%s\"",
                                                   (int) fr_sbuff_diff(&op_m, &our_in), fr_sbuff_current(&our_in),
                                                   da_stack.da[da_stack.depth - 1]->name);
                                goto error;
                        }
 
                alloc_unknown:
                        /*
                         *      We looked up raw.FOO, and FOO wasn't found.  See if we can still parse it.
                         */
                        if (da_stack.da[da_stack.depth - 1]->type == FR_TYPE_GROUP) {
                                fr_strerror_printf("Cannot create 'raw' children in attribute %s of data type 'group'",
                                                   da_stack.da[da_stack.depth - 1]->name);
                                goto error;
                        }
 
                        /*
                         *      Unknown attributes must be 'raw.1234'.
                         */
                        if (!fr_sbuff_is_digit(&our_in)) {
                                goto notfound;
                        }
 
                        /*
                         *      Figure out the data type for unknown attributes.  Intermediate attributes are
                         *      structural.  Only the final attribute is forced to "raw_type".
                         */
                        if (i < components) {
                                if (parent->type == FR_TYPE_VSA) {
                                        unknown_type = FR_TYPE_VENDOR;
                                } else {
                                        unknown_type = FR_TYPE_TLV;
                                }
 
                        } else if (raw_type == FR_TYPE_NULL) {
                                unknown_type = FR_TYPE_OCTETS;
 
                        } else if ((raw_type == FR_TYPE_TLV) && (parent->type == FR_TYPE_VSA)) {
                                /*
                                 *      We had previously parsed a known VSA, but this component is
                                 *      perhaps a numerical OID.  Set the data type to VENDOR, so that
                                 *      the hierachy is correct.
                                 */
                                unknown_type = FR_TYPE_VENDOR;
 
                        } else {
                                unknown_type = raw_type;
                        }
 
                        da_unknown = fr_dict_attr_unknown_afrom_oid(root->ctx, parent, &our_in, unknown_type);
                        if (!da_unknown) goto error;
 
                        da = da_unknown;
                        was_unknown = true;
 
                        goto next;
                } /* huge block of "we didn't find a known attribute" */
 
                /*
                 *      We found the component.  It MIGHT be an ALIAS which jumps down a few levels.  Or, it
                 *      might be a group which jumps back to the dictionary root.  Or it may suddenly be an
                 *      internal attribute.
                 *
                 *      For an ALIAS, we need to add intermediate nodes up to the parent.
                 *
                 *      For a GROUP, we need to add nodes up to the ref of the group.
                 *
                 *      For internal attributes, we need to add nodes up to the root of the internal
                 *      dictionary.
                 */
                if (da->parent != parent) {
                        int j, diff;
                        fr_dict_attr_t const *up;
 
                        ref = parent;
 
                found:
                        fr_assert(fr_dict_attr_common_parent(ref, da, true) == ref);
 
                        diff = da->depth - ref->depth;
                        fr_assert(diff >= 1);
 
                        diff--;
 
                        if ((da_stack.depth + diff) >= FR_DICT_MAX_TLV_STACK) {
                                fr_strerror_printf("Attributes are nested too deeply at \"%.*s\"",
                                                   (int) fr_sbuff_diff(&op_m, &lhs_m), fr_sbuff_current(&lhs_m));
                                goto error;
                        }
 
                        /*
                         *      Go back up the da_stack, setting the parent.
                         */
                        up = da;
                        for (j = da_stack.depth + diff; j >= da_stack.depth; j--) {
                                da_stack.da[j] = up;
                                up = up->parent;
                        }
 
                        for (j = da_stack.depth; j <= da_stack.depth + diff; j++) {
                                fr_assert(da_stack.da[j] != NULL);
                        }
 
                        /*
                         *      Record that we've added more attributes to the da_stack.
                         */
                        da_stack.depth += diff;
                }
 
        next:
                /*
                 *      Limit the data types that we can parse.  This check is mainly to get better error
                 *      messages.
                 */
                switch (da->type) {
                case FR_TYPE_GROUP:
                        if (raw && (raw_type != FR_TYPE_OCTETS)) {
                                fr_strerror_printf("Cannot create 'raw' attributes for data type '%s'", fr_type_to_str(da->type));
                                goto error;
                        }
                        break;
 
                case FR_TYPE_STRUCTURAL_EXCEPT_GROUP:
                case FR_TYPE_LEAF:
                        break;
 
                default:
                        fr_strerror_printf("Invalid data type '%s'", fr_type_to_str(da->type));
                        goto error;
                }
 
                /*
                 *      Everything until the last component must end with a '.', because otherwise there would
                 *      be no next component.
                 */
                if (i < components) {
                        if (!fr_sbuff_next_if_char(&our_in, '.')) {
                                fr_strerror_printf("Missing '.' at \"%.*s\"",
                                                   (int) fr_sbuff_diff(&op_m, &lhs_m), fr_sbuff_current(&lhs_m));
                                goto error;
                        }
 
                        /*
                         *      Leaf attributes cannot appear in the middle of the OID list.
                         */
                        if (fr_type_is_leaf(da->type)) {
                                if (fr_dict_attr_is_key_field(da)) {
                                        fr_strerror_printf("Please remove the reference to key field '%s' from the input string",
                                                           da->name);
                                } else {
                                        fr_strerror_printf("Leaf attribute '%s' cannot have children", da->name);
                                }
 
                                goto error;
                        }
 
                } else if (raw && !da->flags.is_unknown) {
                        /*
                         *      Only the last component can be raw.  If the attribute we found isn't unknown,
                         *      then create an unknown DA from the known one.
                         *
                         *      We have parsed the full OID tree, *and* found a known attribute.  e.g. raw.Vendor-Specific = ...
                         *
                         *      For some reason, we allow: raw.Vendor-Specific = { ... }
                         *
                         *      But this is what we really want: raw.Vendor-Specific = 0xabcdef
                         */
                        if ((raw_type != FR_TYPE_OCTETS) && (raw_type != da->type)) {
                                /*
                                 *      @todo - because it breaks a lot of the encoders.
                                 */
                                fr_strerror_printf("Cannot create raw attribute %s which changes data type from %s to %s",
                                                   da->name, fr_type_to_str(da->type), fr_type_to_str(raw_type));
                                fr_sbuff_set(&our_in, &lhs_m);
                                goto error;
                        }
 
                        da_unknown = fr_dict_attr_unknown_alloc(root->ctx, da, raw_type);
                        if (!da_unknown) goto error;
 
                        da = da_unknown;
                        was_unknown = true;
                }
 
                da_stack.da[da_stack.depth] = da;
        }
 
        /*
         *      at least [0]=root, [1]=da, [2]=NULL
         */
        if (da_stack.depth <= 1) {
                fr_strerror_const("Internal sanity check failed on depth 1");
                return fr_sbuff_error(&our_in);
        }
 
        if (da_stack.depth <= components) {
                fr_strerror_const("Internal sanity check failed on depth 2");
                return fr_sbuff_error(&our_in);
        }
 
        /*
         *      STEP 5: Reset the parser to the value, and double-check if it's what we expect.
         */
        fr_sbuff_set(&our_in, &rhs_m);
 
        if (fr_type_is_structural(da_stack.da[da_stack.depth - 1]->type)) {
                if (!fr_sbuff_is_char(&our_in, '{')) {
                        fr_strerror_printf("Group list for %s MUST start with '{'", da_stack.da[da_stack.depth - 1]->name);
                        goto error;
                }
 
                /*
                 *      The fr_pair_validate() function doesn't support operators for structural attributes,
                 *      so we forbid them here.
                 */
                if (relative->allow_compare && (op != T_OP_EQ) && (op != T_OP_CMP_EQ)) {
                        fr_strerror_printf("Structural attribute '%s' must use '=' or '==' for comparisons",
                                           da_stack.da[da_stack.depth - 1]->name);
                        goto error;
                }
 
                /*
                 *      If we have "foo = { ... }", then we just create the attribute.
                 */
                if (components == 1) append = (op != T_OP_EQ);
        }
 
#if 0
        /*
         *      STEP 5.1: Flatten the hierarchy if necessary.
         */
        if ((relative->da->flags.allow_flat) && (da_stack.depth > 2)) {
                da_stack.da[1] = da_stack.da[da_stack.depth - 1];
 
                da_stack.depth = 2;
        }
#endif
 
        /*
         *      STEP 6: Use the da_stack to either find or add intermediate #fr_pair_t.
         */
        my = *relative;
        for (i = 1; i < da_stack.depth; i++) {
                fr_dict_attr_t const *da;
 
                da = da_stack.da[i];
 
                /*
                 *      When we have a full path that contains MEMBERs of a STRUCT, we need to check ordering.
                 *      The children MUST be added in order.  If we see a child that is out of order, then
                 *      that means we need to start a new parent STRUCT.
                 */
                if ((da->parent->type == FR_TYPE_STRUCT) && (i > 1)) {
                        fr_assert(da_stack.da[i - 1] == da->parent);
                        fr_assert(da_stack.vp[i - 1] != NULL);
                        fr_assert(my.ctx == da_stack.vp[i - 1]);
 
                        /*
                         *      @todo - cache the last previous child that we added?  Or maybe the DA of the
                         *      last child?
                         */
                        for (vp = fr_pair_list_tail(my.list);
                             vp != NULL;
                             vp = fr_pair_list_prev(my.list, vp)) {
                                if (!vp->da->flags.internal) break;
                        }
 
                        if (vp && (vp->da->attr > da->attr)) {
                                fr_pair_t *parent = da_stack.vp[i - 2];
 
                                if (parent) {
                                        if (fr_pair_append_by_da(parent, &vp, &parent->vp_group, da->parent) < 0) {
                                                goto error;
                                        }
                                } else {
                                        if (fr_pair_append_by_da(root->ctx, &vp, root->list, da->parent) < 0) {
                                                goto error;
                                        }
                                }
 
                                vp->op = T_OP_EQ;
                                PAIR_ALLOCED(vp);
                                my.ctx = vp;
                                my.list = &vp->vp_group;
                        }
                }
 
                /*
                 *      Everything up to the last entry must be structural.
                 *
                 *      The last entry may be structural, or else it might be a leaf.
                 */
                if (fr_type_is_structural(da->type)) {
                        if (append) {
                                vp = fr_pair_find_last_by_da(my.list, da);
                                if (vp) goto update_relative;
                        }
 
                        if (fr_pair_append_by_da(my.ctx, &vp, my.list, da) < 0) {
                                goto error;
                        }
 
                        vp->op = T_OP_EQ;
                        PAIR_ALLOCED(vp);
 
                update_relative:
                        da_stack.vp[i] = vp;
 
                        my.ctx = vp;
                        my.da = vp->da;
                        my.list = &vp->vp_group;
                        continue;
                }
 
                /*
                 *      We're finally at the leaf attribute, which must be the last attribute.
                 */
                fr_assert(i == (da_stack.depth - 1));
 
                vp = fr_pair_afrom_da(my.ctx, da);
                if (!vp) goto error;
 
                PAIR_ALLOCED(vp);
                vp->op = op;
                da_stack.vp[i] = vp;
        }
 
        /*
         *      Intermediate nodes always use the operator '='.  The final one uses the assigned operator.
         */
        fr_assert(vp != NULL);
        fr_assert(vp->op != T_INVALID);
 
        /*
         *      STEP 7: Parse the value, recursing if necessary.
         *
         *      @todo - do all kinds of cleanups if anything fails.  TBH, this really needs the edit lists,
         *      and that might be a bit much overhead for this code.
         */
        if (fr_type_is_structural(vp->da->type)) {
                fr_pair_parse_t child = (fr_pair_parse_t) {
                        .allow_compare = root->allow_compare,
                        .dict = root->dict,
                        .internal = root->internal,
                };
 
                if (!fr_sbuff_next_if_char(&our_in, '{')) {
                        fr_strerror_printf("Child list for %s MUST start with '{'", vp->da->name);
                        goto error;
                }
 
                fr_assert(my.ctx == vp);
                fr_assert(my.da == vp->da);
                fr_assert(my.list == &vp->vp_group);
                my.allow_compare = root->allow_compare;
                my.end_of_list = true;
 
                while (true) {
                        fr_sbuff_adv_past_blank(&our_in, SIZE_MAX, NULL);
 
                        if (fr_sbuff_is_char(&our_in, '}')) {
                                break;
                        }
 
                        slen = fr_pair_list_afrom_substr(&my, &child, &our_in);
                        if (!slen) break;
 
                        if (slen < 0) goto error;
                }
 
                if (!fr_sbuff_next_if_char(&our_in, '}')) {
                        fr_strerror_const("Failed to end list with '}'");
                        goto error;
                }
 
                /*
                 *      This structure was the last thing we parsed.  The next thing starts from here.
                 */
                *relative = my;
 
        } else {
                slen = fr_pair_value_from_substr(root, vp, &our_in);
                if (slen <= 0) goto error;
 
                fr_pair_append(my.list, vp);
        }
 
        PAIR_VERIFY(vp);
 
        CLEAN_DA_STACK;
 
        fr_sbuff_adv_past_blank(&our_in, SIZE_MAX, NULL);
 
        /*
         *      STEP 8: See if we're done, or if we need to stop parsing this #fr_pair_t.
         *
         *      Allow a limited set of characters after a value.
         *
         *      It can be "," OR "CRLF" OR ",CRLF".  But not anything else.
         */
        keep_going = false;
        if (fr_sbuff_next_if_char(&our_in, ',')) {
                fr_sbuff_adv_past_blank(&our_in, SIZE_MAX, NULL);
 
                keep_going = true;
                relative->last_char = ',';
        }
 
        /*
         *      We hit the end of the parent list.  There's no need to update "relative", we just return, and
         *      let the caller end the list.
         *
         *      Note that we allow trailing commas:  Foo = { Bar = Baz, }
         *
         *      We don't care about any trailing data.
         */
        if (relative->end_of_list && fr_sbuff_is_char(&our_in, '}')) {
                relative->last_char = '\0';
                goto done;
        }
 
        if (relative->allow_crlf) {
                size_t len;
 
                len = fr_sbuff_adv_past_allowed(&our_in, SIZE_MAX, sbuff_char_line_endings, NULL);
                if (len) {
                        keep_going = true;
                        if (!relative->last_char) relative->last_char = '\n';
                }
        }
 
        /*
         *      This is mainly for the detail file reader.  We allow zeros as end of "attr op value".  But we
         *      also treat zeros as "don't keep going".
         */
        if (relative->allow_zeros) {
                while (fr_sbuff_next_if_char(&our_in, '\0')) {
                        /* nothing */
                }
 
                goto done;
        }
 
        /*
         *      There's no more input, we're done.  Any next attributes will cause the input to be parsed from
         *      the root again.
         */
        (void) fr_sbuff_extend(&our_in);
        if (!fr_sbuff_remaining(&our_in)) goto done;
 
        /*
         *      STEP 9: If we need to keep going, then set up the relative references based on what we've
         *      done, and go back to start over again.
         *
         *      The caller is responsible for checking whether or not we have too much data.
         */
        if (keep_going) {
                /*
                 *      Update the relative list for parsing the next pair.
                 */
                if (fr_type_is_leaf(vp->da->type)) {
                        fr_pair_t *parent;
 
                        parent = fr_pair_parent(vp);
                        if (!parent) {
                                *relative = *root;
 
                        } else {
                                relative->ctx = parent;
                                relative->da = parent->da;
                                relative->list = &parent->vp_group;
                        }
 
                } else {
                        relative->ctx = vp;
                        relative->da = vp->da;
                        relative->list = &vp->vp_group;
                }
 
                goto redo;
        }
 
        /*
         *      STEP 10: Complain if we have unexpected input.
         *
         *      We have more input, BUT we didn't have a comma or CRLF to explicitly finish the last pair we
         *      read.  That's a problem.
         */
        if (!relative->last_char) {
                size_t remaining;
 
                remaining = fr_sbuff_remaining(&our_in);
 
                if (remaining > 20) remaining = 20;
 
                fr_strerror_printf("Unexpected text '%.*s ...' after value",
                                   (int) remaining, fr_sbuff_current(&our_in));
                return fr_sbuff_error(&our_in); /* da_stack has already been cleaned */
        }
 
done:
        /*
         *      STEP 11: Finally done.
         */
        FR_SBUFF_SET_RETURN(in, &our_in);
}
 
/** Read valuepairs from the fp up to End-Of-File.
 *
 * @param[in] ctx               for talloc
 * @param[in] dict              to resolve attributes in.
 * @param[in,out] out           where the parsed fr_pair_ts will be appended.
 * @param[in] fp                to read valuepairs from.
 * @param[out] pfiledone        true if file parsing complete;
 * @param[in] allow_exec        Whether we allow `backtick` expansions.
 * @return
 *      - 0 on success
 *      - -1 on error
 */
int fr_pair_list_afrom_file(TALLOC_CTX *ctx, fr_dict_t const *dict, fr_pair_list_t *out, FILE *fp, bool *pfiledone, bool allow_exec)
{
        fr_pair_list_t tmp_list;
        fr_pair_parse_t root, relative;
        bool            found = false;
        char            buf[8192];
 
        /*
         *      Read all of the attributes on the current line.
         *
         *      If we get nothing but an EOL, it's likely OK.
         */
        fr_pair_list_init(&tmp_list);
 
        root = (fr_pair_parse_t) {
                .ctx = ctx,
                .da = fr_dict_root(dict),
                .list = &tmp_list,
                .dict = dict,
                .internal = fr_dict_internal(),
                .allow_crlf = true,
                .allow_compare = true,
                .allow_exec = allow_exec
        };
        relative = (fr_pair_parse_t) { };
 
        while (fgets(buf, sizeof(buf), fp) != NULL) {
                /*
                 *      If we get a '\n' by itself, we assume that's
                 *      the end of that VP list.
                 */
                if ((buf[0] == '\n') || (buf[0] == '\r')) {
                        if (found) {
                                *pfiledone = false;
                                break;
                        }
                        continue;
                }
 
                /*
                 *      Comments get ignored
                 */
                if (buf[0] == '#') continue;
 
                /*
                 *      Leave "relative" between calls, so that we can do:
                 *
                 *              foo = {}
                 *              .bar = baz
                 *
                 *      and get
                 *
                 *              foo = { bar = baz }
                 */
                if (fr_pair_list_afrom_substr(&root, &relative, &FR_SBUFF_IN_STR(buf)) < 0) {
                        *pfiledone = false;
                        fr_pair_list_free(&tmp_list);
                        return -1;
                }
 
                found = true;
        }
 
#ifdef WITH_VERIFY_PTR
        fr_pair_list_verify(__FILE__, __LINE__, ctx, &tmp_list, true);
#endif
 
        fr_pair_list_append(out, &tmp_list);
 
        *pfiledone = true;
        return 0;
}
 
 
/** Move pairs from source list to destination list respecting operator
 *
 * @note This function does some additional magic that's probably not needed in most places. Consider using
 *       radius_legacy_map_cmp() and radius_legacy_map_apply() instead.
 *
 * @note fr_pair_list_free should be called on the head of the source list to free
 *       unmoved attributes (if they're no longer needed).
 *
 * @param[in,out] to destination list.
 * @param[in,out] from source list.
 * @param[in] op operator for list move.
 */
void fr_pair_list_move_op(fr_pair_list_t *to, fr_pair_list_t *from, fr_token_t op)
{
        fr_pair_t *vp, *next, *found;
        fr_pair_list_t head_append, head_prepend;
 
        if (!to || fr_pair_list_empty(from)) return;
 
        /*
         *      We're editing the "to" list while we're adding new
         *      attributes to it.  We don't want the new attributes to
         *      be edited, so we create an intermediate list to hold
         *      them during the editing process.
         */
        fr_pair_list_init(&head_append);
 
        /*
         *      Any attributes that are requested to be prepended
         *      are added to a temporary list here
         */
        fr_pair_list_init(&head_prepend);
 
        /*
         *      We're looping over the "from" list, moving some
         *      attributes out, but leaving others in place.
         */
        for (vp = fr_pair_list_head(from); vp != NULL; vp = next) {
                PAIR_VERIFY(vp);
                next = fr_pair_list_next(from, vp);
 
                /*
                 *      We never move Fall-Through.
                 */
                if (fr_dict_attr_is_top_level(vp->da) && (vp->da->attr == FR_FALL_THROUGH) &&
                    (fr_dict_by_da(vp->da) == fr_dict_internal())) {
                        continue;
                }
 
                /*
                 *      Unlike previous versions, we treat all other
                 *      attributes as normal.  i.e. there's no special
                 *      treatment for passwords or Hint.
                 */
 
                switch (vp->op) {
                /*
                 *      Anything else are operators which
                 *      shouldn't occur.  We ignore them, and
                 *      leave them in place.
                 */
                default:
                        continue;
 
                /*
                 *      Add it to the "to" list, but only if
                 *      it doesn't already exist.
                 */
                case T_OP_EQ:
                        found = fr_pair_find_by_da(to, NULL, vp->da);
                        if (!found) goto do_add;
                        continue;
 
                /*
                 *      Add it to the "to" list, and delete any attribute
                 *      of the same vendor/attr which already exists.
                 */
                case T_OP_SET:
                        found = fr_pair_find_by_da(to, NULL, vp->da);
                        if (!found) goto do_add;
 
                        /*
                         *      Delete *all* matching attributes.
                         */
                        fr_pair_delete_by_da(to, found->da);
                        goto do_add;
 
                /*
                 *      Move it from the old list and add it
                 *      to the new list.
                 */
                case T_OP_ADD_EQ:
        do_add:
                        fr_pair_remove(from, vp);
                        fr_pair_append(&head_append, vp);
                        continue;
 
                case T_OP_PREPEND:
                        fr_pair_remove(from, vp);
                        fr_pair_prepend(&head_prepend, vp);
                        continue;
                }
        } /* loop over the "from" list. */
 
        /*
         *      If the op parameter was prepend, add the "new list
         *      attributes first as those whose individual operator
         *      is prepend should be prepended to the resulting list
         */
        if (op == T_OP_PREPEND) fr_pair_list_prepend(to, &head_append);
 
        /*
         *      If there are any items in the prepend list prepend
         *      it to the "to" list
         */
        fr_pair_list_prepend(to, &head_prepend);
 
        /*
         *      If the op parameter was not prepend, take the "new"
         *      list, and append it to the "to" list.
         */
        if (op != T_OP_PREPEND) fr_pair_list_append(to, &head_append);
 
        fr_pair_list_free(from);
}