pair.h

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#pragma once
/*
 *  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: 6f596aaa91c7d118164a98c7b9d69f076b75de1c $
 *
 * @file io/pair.h
 * @brief Encoder/decoder library interface
 *
 * @copyright 2017-2020 The FreeRADIUS project
 */
#include <freeradius-devel/util/dcursor.h>
#include <freeradius-devel/util/value.h>
#include <freeradius-devel/util/pair.h>
 
/** @name Encoder errors
 * @{
 */
 
/** Fatal encoding error
 */
#define PAIR_ENCODE_FATAL_ERROR SSIZE_MIN
 
/** @} */
 
/** @name Decode errors
 * @{
 */
/** Fatal error - Out of memory
 */
#define PAIR_DECODE_OOM         FR_VALUE_BOX_NET_OOM
 
/** Fatal error - Failed decoding the packet
 */
#define PAIR_DECODE_FATAL_ERROR FR_VALUE_BOX_NET_ERROR
 
/** Return the correct adjusted slen for errors
 *
 * @param[in] slen      returned from the function we called.
 * @param[in] start     of the buffer.
 * @param[in] p         offset passed to function which returned the slen.
 */
static inline ssize_t fr_pair_decode_slen(ssize_t slen, uint8_t const *start, uint8_t const *p)
{
        if (slen > 0) return slen;
 
        switch (slen) {
        case PAIR_DECODE_OOM:
        case PAIR_DECODE_FATAL_ERROR:
                return slen;
 
        default:
                return slen - (p - start);
        }
}
 
/** Determine if the return code for an encoding function is a fatal error
 *
 */
static inline bool fr_pair_encode_is_error(ssize_t slen)
{
        if (slen == PAIR_ENCODE_FATAL_ERROR) return true;
        return false;
}
 
/** Checks if we have sufficient buffer space, and returns how much space we'd need as a negative integer
 *
 */
#define FR_PAIR_ENCODE_HAVE_SPACE(_p, _end, _num) if (((_p) + (_num)) > (_end)) return (_end) - ((_p) + (_num));
 
/** @} */
 
/** Generic interface for encoding one or more fr_pair_ts
 *
 * An encoding function should consume at most, one top level fr_pair_t and encode
 * it in the appropriate wire format for the protocol, writing the encoded data to
 * out, and returning the encoded length.
 *
 * The exception to processing one fr_pair_t is if multiple fr_pair_ts can be aggregated
 * into a single TLV, in which case the encoder may consume as many fr_pair_ts as will
 * fit into that TLV.
 *
 * Outlen provides the length of the buffer to write the encoded data to.  The return
 * value must not be greater than outlen.
 *
 * The cursor is used to track how many pairs there are remaining.
 *
 * @param[out] out              Where to write the encoded data.
 * @param[in] cursor            Cursor containing the list of attributes to process.
 * @param[in] encode_ctx        Any encoder specific data such as secrets or configurables.
 * @return
 *      - PAIR_ENCODE_FATAL_ERROR - Encoding failed in a fatal way. Encoding the packet should be
 *        aborted in its entirety.
 *      - <0 - The encoder ran out of space and returned the number of bytes as a negative
 *        integer that would be required to encode the attribute.
 *      - >0 - The number of bytes written to out.
 */
typedef ssize_t (*fr_pair_encode_t)(fr_dbuff_t *out, fr_dcursor_t *cursor, void *encode_ctx);
 
/** A generic interface for decoding fr_pair_ts
 *
 * A decoding function should decode a single top level fr_pair_t from wire format.
 * If this top level fr_pair_t is a TLV, multiple child attributes may also be decoded.
 *
 * @param[in] ctx               to allocate new pairs in.
 * @param[in] out               to insert new pairs into.
 * @param[in] parent            to use for decoding
 * @param[in] data              to decode.
 * @param[in] data_len          The length of the incoming data.
 * @param[in] decode_ctx        Any decode specific data such as secrets or temporary allocation contexts
 * @return
 *      - <= 0 on error.  May be the offset (as a negative value) where the error occurred.
 *      - > 0 on success.  How many bytes were decoded.
 */
typedef ssize_t (*fr_pair_decode_t)(TALLOC_CTX *ctx, fr_pair_list_t *out, fr_dict_attr_t const *parent,
                                    uint8_t const *data, size_t data_len, void *decode_ctx);