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[u/mdw/catacomb] / buf.h

/* -*-c-*-
 *
 * $Id: buf.h,v 1.1 2003/10/11 21:02:33 mdw Exp $
 *
 * [Reading and writing packet buffers *
 * (c) 2001 Straylight/Edgeware
 */

/*----- Licensing notice --------------------------------------------------* 
 *
 * This file is part of Catacomb.
 *
 * Catacomb is free software; you can redistribute it and/or modify
 * it under the terms of the GNU Library General Public License as
 * published by the Free Software Foundation; either version 2 of the
 * License, or (at your option) any later version.
 * 
 * Catacomb 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 Library General Public License for more details.
 * 
 * You should have received a copy of the GNU Library General Public
 * License along with Catacomb; if not, write to the Free
 * Software Foundation, Inc., 59 Temple Place - Suite 330, Boston,
 * MA 02111-1307, USA.
 */

/*----- Revision history --------------------------------------------------* 
 *
 * $Log: buf.h,v $
 * Revision 1.1  2003/10/11 21:02:33  mdw
 * Import buf stuff from tripe.
 *
 * Revision 1.1  2001/06/19 22:09:54  mdw
 * Expose interface, for use in the proxy.
 *
 */

#ifndef BUF_H
#define BUF_H

#ifdef __cplusplus
  extern "C" {
#endif

/*----- Header files ------------------------------------------------------*/

#include <stddef.h>

#include <mLib/bits.h>

#include <catacomb/mp.h>

/*----- Data structures ---------------------------------------------------*/

/* --- Buffers --- *
 *
 * Buffers provide a simple stream-like interface for building and parsing
 * packets.
 */

typedef struct buf {
  octet *base, *p, *limit;		/* Pointers to the buffer */
  unsigned f;				/* Various flags */
} buf;

#define BF_BROKEN 1u			/* Buffer is broken */

/*----- Useful macros -----------------------------------------------------*/

#define BBASE(b) ((b)->base)
#define BLIM(b) ((b)->limit)
#define BCUR(b) ((b)->p)
#define BSZ(b) ((b)->limit - (b)->base)
#define BLEN(b) ((b)->p - (b)->base)
#define BLEFT(b) ((b)->limit - (b)->p)
#define BSTEP(b, sz) ((b)->p += (sz))
#define BBAD(b) ((b)->f & BF_BROKEN)
#define BOK(b) (!BBAD(b))

#define BENSURE(b, sz)							\
  (BBAD(b) ? -1 : (sz) > BLEFT(b) ? (b)->f |= BF_BROKEN, -1 : 0)

/*----- Functions provided ------------------------------------------------*/

/* --- @buf_init@ --- *
 *
 * Arguments:	@buf *b@ = pointer to a buffer block
 *		@void *p@ = pointer to a buffer
 *		@size_t sz@ = size of the buffer
 *
 * Returns:	---
 *
 * Use:		Initializes the buffer block appropriately.
 */

extern void buf_init(buf */*b*/, void */*p*/, size_t /*sz*/);

/* --- @buf_break@ --- *
 *
 * Arguments:	@buf *b@ = pointer to a buffer block
 *
 * Returns:	Some negative value.
 *
 * Use:		Marks a buffer as broken.
 */

extern int buf_break(buf */*b*/);

/* --- @buf_flip@ --- *
 *
 * Arguments:	@buf *b@ = pointer to a buffer block
 *
 * Returns:	---
 *
 * Use:		Flips a buffer so that if you've just been writing to it,
 *		you can now read from the bit you've written.
 */

extern void buf_flip(buf */*b*/);

/* --- @buf_ensure@ --- *
 *
 * Arguments:	@buf *b@ = pointer to a buffer block
 *		@size_t sz@ = size of data wanted
 *
 * Returns:	Zero if it worked, nonzero if there wasn't enough space.
 *
 * Use:		Ensures that there are @sz@ bytes still in the buffer.
 */

extern int buf_ensure(buf */*b*/, size_t /*sz*/);

/* --- @buf_get@ --- *
 *
 * Arguments:	@buf *b@ = pointer to a buffer block
 *		@size_t sz@ = size of the buffer
 *
 * Returns:	Pointer to the place in the buffer.
 *
 * Use:		Reserves a space in the buffer of the requested size, and
 *		returns its start address.
 */

extern void *buf_get(buf */*b*/, size_t /*sz*/);

/* --- @buf_put@ --- *
 *
 * Arguments:	@buf *b@ = pointer to a buffer block
 *		@const void *p@ = pointer to a buffer
 *		@size_t sz@ = size of the buffer
 *
 * Returns:	Zero if it worked, nonzero if there wasn't enough space.
 *
 * Use:		Fetches data from some place and puts it in the buffer
 */

extern int buf_put(buf */*b*/, const void */*p*/, size_t /*sz*/);

/* --- @buf_getbyte@ --- *
 *
 * Arguments:	@buf *b@ = pointer to a buffer block
 *
 * Returns:	A byte, or less than zero if there wasn't a byte there.
 *
 * Use:		Gets a single byte from a buffer.
 */

extern int buf_getbyte(buf */*b*/);

/* --- @buf_putbyte@ --- *
 *
 * Arguments:	@buf *b@ = pointer to a buffer block
 *		@int ch@ = byte to write
 *
 * Returns:	Zero if OK, nonzero if there wasn't enough space.
 *
 * Use:		Puts a single byte in a buffer.
 */

extern int buf_putbyte(buf */*b*/, int /*ch*/);

/* --- @buf_getu16@ --- *
 *
 * Arguments:	@buf *b@ = pointer to a buffer block
 *		@uint16 *w@ = where to put the word
 *
 * Returns:	Zero if OK, or nonzero if there wasn't a word there.
 *
 * Use:		Gets a 16-bit word from a buffer.
 */

extern int buf_getu16(buf */*b*/, uint16 */*w*/);

/* --- @buf_putu16@ --- *
 *
 * Arguments:	@buf *b@ = pointer to a buffer block
 *		@uint16 w@ = word to write
 *
 * Returns:	Zero if OK, nonzero if there wasn't enough space.
 *
 * Use:		Puts a 16-but word in a buffer.
 */

extern int buf_putu16(buf */*b*/, uint16 /*w*/);

/* --- @buf_getu32@ --- *
 *
 * Arguments:	@buf *b@ = pointer to a buffer block
 *		@uint32 *w@ = where to put the word
 *
 * Returns:	Zero if OK, or nonzero if there wasn't a word there.
 *
 * Use:		Gets a 32-bit word from a buffer.
 */

extern int buf_getu32(buf */*b*/, uint32 */*w*/);

/* --- @buf_putu32@ --- *
 *
 * Arguments:	@buf *b@ = pointer to a buffer block
 *		@uint32 w@ = word to write
 *
 * Returns:	Zero if OK, nonzero if there wasn't enough space.
 *
 * Use:		Puts a 32-but word in a buffer.
 */

extern int buf_putu32(buf */*b*/, uint32 /*w*/);

/* --- @buf_getmp@ --- *
 *
 * Arguments:	@buf *b@ = pointer to a buffer block
 *
 * Returns:	A multiprecision integer, or null if there wasn't one there.
 *
 * Use:		Gets a multiprecision integer from a buffer.
 */

extern mp *buf_getmp(buf */*b*/);

/* --- @buf_putmp@ --- *
 *
 * Arguments:	@buf *b@ = pointer to a buffer block
 *		@mp *m@ = a multiprecision integer
 *
 * Returns:	Zero if it worked, nonzero if there wasn't enough space.
 *
 * Use:		Puts a multiprecision integer to a buffer.
 */

extern int buf_putmp(buf */*b*/, mp */*m*/);

/*----- That's all, folks -------------------------------------------------*/

#ifdef __cplusplus
  }
#endif

#endif