rlm_unpack.c

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/*
 *   This program is 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: cad6d9c8bdc58c06e644b93fef195be8c634d526 $
 * @file rlm_unpack.c
 * @brief Unpack binary data
 *
 * @copyright 2014 The FreeRADIUS server project
 * @copyright 2014 Alan DeKok (aland@freeradius.org)
 */
RCSID("$Id: cad6d9c8bdc58c06e644b93fef195be8c634d526 $")
 
#include <freeradius-devel/server/base.h>
#include <freeradius-devel/server/module_rlm.h>
#include <freeradius-devel/unlang/xlat_func.h>
#include <freeradius-devel/util/base16.h>
 
#include <ctype.h>
 
static xlat_arg_parser_t const unpack_xlat_args[] = {
        { .required = true, .single = true, .type = FR_TYPE_VOID },
        { .required = true, .single = true, .type = FR_TYPE_UINT32 },
        { .required = true, .single = true, .type = FR_TYPE_STRING },
        { .single = true, .type = FR_TYPE_VOID },
        XLAT_ARG_PARSER_TERMINATOR
};
 
/** Unpack data
 *
 * Example:
@verbatim
%unpack(%{Class}, 0, integer)
@endverbatim
 * Expands Class, treating octet at offset 0 (bytes 0-3) as an "integer".
 *
 * @ingroup xlat_functions
 */
static xlat_action_t unpack_xlat(TALLOC_CTX *ctx, fr_dcursor_t *out,
                                 UNUSED xlat_ctx_t const *xctx, request_t *request,
                                 fr_value_box_list_t *in)
{
        size_t          len, input_len, offset;
        fr_type_t       type;
        uint8_t const   *input;
        uint8_t         blob[256];
        uint32_t        repeat = 1, count = 1;
        fr_value_box_t  *data_vb = fr_value_box_list_head(in);
        fr_value_box_t  *offset_vb = fr_value_box_list_next(in, data_vb);
        fr_value_box_t  *type_vb = fr_value_box_list_next(in, offset_vb);
        fr_value_box_t  *repeat_vb = fr_value_box_list_next(in, type_vb);
        fr_value_box_t  *vb;
        ssize_t         used;
 
        if ((data_vb->type != FR_TYPE_OCTETS) && (data_vb->type != FR_TYPE_STRING)) {
                REDEBUG("unpack requires the input attribute to be 'string' or 'octets'");
                return XLAT_ACTION_FAIL;
        }
 
        if ((data_vb->type == FR_TYPE_STRING) && (data_vb->vb_length > 1) &&
            (data_vb->vb_strvalue[0] == '0') && (data_vb->vb_strvalue[1] == 'x')) {
                /*
                 *      Hex data.
                 */
                len = strlen(data_vb->vb_strvalue + 2);
                if (len > 0) {
                        fr_sbuff_parse_error_t err;
 
                        input = blob;
                        input_len = fr_base16_decode(&err, &FR_DBUFF_TMP(blob, sizeof(blob)),
                                               &FR_SBUFF_IN(data_vb->vb_strvalue + 2, len), true);
                        if (err) {
                                REDEBUG("Invalid hex string in '%s'", data_vb->vb_strvalue);
                                return XLAT_ACTION_FAIL;
                        }
                } else {
                        REDEBUG("Zero length hex string in '%s'", data_vb->vb_strvalue);
                        return XLAT_ACTION_FAIL;
                }
        } else if (data_vb->type == FR_TYPE_STRING) {
                input = (uint8_t const *)data_vb->vb_strvalue;
                input_len = data_vb->vb_length;
        } else {
                input = data_vb->vb_octets;
                input_len = data_vb->vb_length;
        }
 
        offset = offset_vb->vb_uint32;
 
        if (offset >= input_len) {
                REDEBUG("unpack offset %zu is larger than input data length %zu", offset, input_len);
                return XLAT_ACTION_FAIL;
        }
 
        /* coverity[dereference] */
        type = fr_type_from_str(type_vb->vb_strvalue);
        if (fr_type_is_null(type)) {
                REDEBUG("Invalid data type '%s'", type_vb->vb_strvalue);
                return XLAT_ACTION_FAIL;
        }
 
        if (repeat_vb) {
                if ((repeat_vb->type == FR_TYPE_STRING) && (strcmp(repeat_vb->vb_strvalue, "*") == 0)) {
                        repeat = UINT32_MAX;
                } else {
                        if (fr_value_box_cast_in_place(repeat_vb, repeat_vb, FR_TYPE_UINT32, NULL) < 0) {
                                REDEBUG("Invalid value for limit");
                                return XLAT_ACTION_FAIL;
                        }
                        repeat = repeat_vb->vb_uint32;
                }
        }
 
        while (true) {
                MEM(vb = fr_value_box_alloc_null(ctx));
 
                /*
                 *      Call the generic routines to get data from the
                 *      "network" buffer.
                 */
                used = fr_value_box_from_network(ctx, vb, type, NULL,
                                                 &FR_DBUFF_TMP(input + offset, input_len - offset),
                                                 input_len - offset, data_vb->tainted);
                if (used < 0) {
                        RPEDEBUG("Failed decoding %s", type_vb->vb_strvalue);
                        talloc_free(vb);
                        return XLAT_ACTION_FAIL;
                }
 
                fr_dcursor_append(out, vb);
                if (count == repeat) break;
 
                offset += used;
                if (offset + used > input_len) break;
                count++;
        }
 
        return XLAT_ACTION_DONE;
}
 
/*
 *      Register the xlats
 */
static int mod_load(void)
{
        xlat_t  *xlat;
 
        if (unlikely(!(xlat = xlat_func_register(NULL, "unpack", unpack_xlat, FR_TYPE_VOID)))) return -1;
        xlat_func_args_set(xlat, unpack_xlat_args);
        xlat_func_flags_set(xlat, XLAT_FUNC_FLAG_PURE);
 
        return 0;
}
 
static void mod_unload(void)
{
        xlat_func_unregister("unpack");
}
 
/*
 *      The module name should be the only globally exported symbol.
 *      That is, everything else should be 'static'.
 *
 *      If the module needs to temporarily modify it's instantiation
 *      data, the type should be changed to MODULE_TYPE_THREAD_UNSAFE.
 *      The server will then take care of ensuring that the module
 *      is single-threaded.
 */
extern module_rlm_t rlm_unpack;
module_rlm_t rlm_unpack = {
        .common = {
                .magic          = MODULE_MAGIC_INIT,
                .name           = "unpack",
                .onload         = mod_load,
                .unload         = mod_unload
        }
};