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/*!
* \file utils.h
*
* \author Lubos Slovak <lubos.slovak@nic.cz>
*
* \brief Various utilities.
*
* \addtogroup libknot
* @{
*/
/* Copyright (C) 2011 CZ.NIC, z.s.p.o. <knot-dns@labs.nic.cz>
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 3 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, see <http://www.gnu.org/licenses/>.
*/
#ifndef _KNOT_UTILS_H_
#define _KNOT_UTILS_H_
#include <string.h>
#include <stdint.h>
#include <stdio.h>
/*!
* \brief A general purpose lookup table.
*
* \note Taken from NSD.
*/
struct knot_lookup_table {
int id;
const char *name;
};
typedef struct knot_lookup_table knot_lookup_table_t;
/*!
* \brief Looks up the given name in the lookup table.
*
* \param table Lookup table.
* \param name Name to look up.
*
* \return Item in the lookup table with the given name or NULL if no such is
* present.
*/
knot_lookup_table_t *knot_lookup_by_name(knot_lookup_table_t *table,
const char *name);
/*!
* \brief Looks up the given id in the lookup table.
*
* \param table Lookup table.
* \param id ID to look up.
*
* \return Item in the lookup table with the given id or NULL if no such is
* present.
*/
knot_lookup_table_t *knot_lookup_by_id(knot_lookup_table_t *table,
int id);
/*!
* \brief Strlcpy - safe string copy function, based on FreeBSD implementation.
*
* http://www.openbsd.org/cgi-bin/cvsweb/src/lib/libc/string/
*
* \param dst Destination string.
* \param src Source string.
* \param size How many characters to copy - 1.
*
* \return strlen(src), if retval >= siz, truncation occurred.
*/
size_t knot_strlcpy(char *dst, const char *src, size_t size);
/*
* Writing / reading arbitrary data to / from wireformat.
*/
/*!
* \brief Reads 2 bytes from the wireformat data.
*
* \param pos Data to read the 2 bytes from.
*
* \return The 2 bytes read, in inverse endian.
*/
static inline uint16_t knot_wire_read_u16(const uint8_t *pos)
{
return (pos[0] << 8) | pos[1];
}
/*!
* \brief Reads 4 bytes from the wireformat data.
*
* \param pos Data to read the 4 bytes from.
*
* \return The 4 bytes read, in inverse endian.
*/
static inline uint32_t knot_wire_read_u32(const uint8_t *pos)
{
return (pos[0] << 24) | (pos[1] << 16) | (pos[2] << 8) | pos[3];
}
/*!
* \brief Reads 6 bytes from the wireformat data.
*
* \param pos Data to read the 6 bytes from.
*
* \return The 6 bytes read, in inverse endian.
*/
static inline uint64_t knot_wire_read_u48(const uint8_t *pos)
{
return ((uint64_t)(pos[0]) << 40) | ((uint64_t)(pos[1]) << 32) | (pos[2] << 24) |
(pos[3] << 16) | (pos[4] << 8) | pos[5];
}
/*!
* \brief Writes 2 bytes in wireformat.
*
* The endian of the data is inverted.
*
* \param pos Position where to put the 2 bytes.
* \param data Data to put.
*/
static inline void knot_wire_write_u16(uint8_t *pos, uint16_t data)
{
pos[0] = (uint8_t)((data >> 8) & 0xff);
pos[1] = (uint8_t)(data & 0xff);
}
/*!
* \brief Writes 4 bytes in wireformat.
*
* The endian of the data is inverted.
*
* \param pos Position where to put the 4 bytes.
* \param data Data to put.
*/
static inline void knot_wire_write_u32(uint8_t *pos, uint32_t data)
{
pos[0] = (uint8_t)((data >> 24) & 0xff);
pos[1] = (uint8_t)((data >> 16) & 0xff);
pos[2] = (uint8_t)((data >> 8) & 0xff);
pos[3] = (uint8_t)(data & 0xff);
}
/*!
* \brief Writes 6 bytes in wireformat.
*
* The endian of the data is inverted.
*
* \param pos Position where to put the 4 bytes.
* \param data Data to put.
*/
static inline void knot_wire_write_u48(uint8_t *pos, uint64_t data)
{
pos[0] = (uint8_t)((data >> 40) & 0xff);
pos[1] = (uint8_t)((data >> 32) & 0xff);
pos[2] = (uint8_t)((data >> 24) & 0xff);
pos[3] = (uint8_t)((data >> 16) & 0xff);
pos[4] = (uint8_t)((data >> 8) & 0xff);
pos[5] = (uint8_t)(data & 0xff);
}
/*!
* \brief Linear congruential generator.
*
* Simple pseudorandom generator for general purpose.
* \warning Do not use for cryptography.
* \return Random number <0, (size_t)~0>
*/
size_t knot_quick_rand();
uint16_t knot_random_id();
/*!
* \brief Helper function for simple locking.
*
* \param type Type of lock.
* \param type Starting position of lock.
*
* \return Locking structure.
*/
struct flock* knot_file_lock(short type, short whence);
#endif /* _KNOT_UTILS_H_ */
/*! @} */
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