linux/drivers/net/slip/slhc.c

/*
 * Routines to compress and uncompress tcp packets (for transmission
 * over low speed serial lines).
 *
 * Copyright (c) 1989 Regents of the University of California.
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms are permitted
 * provided that the above copyright notice and this paragraph are
 * duplicated in all such forms and that any documentation,
 * advertising materials, and other materials related to such
 * distribution and use acknowledge that the software was developed
 * by the University of California, Berkeley.  The name of the
 * University may not be used to endorse or promote products derived
 * from this software without specific prior written permission.
 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR
 * IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED
 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
 *
 *	Van Jacobson ([email protected]), Dec 31, 1989:
 *	- Initial distribution.
 *
 *
 * modified for KA9Q Internet Software Package by
 * Katie Stevens ([email protected])
 * University of California, Davis
 * Computing Services
 *	- 01-31-90	initial adaptation (from 1.19)
 *	PPP.05	02-15-90 [ks]
 *	PPP.08	05-02-90 [ks]	use PPP protocol field to signal compression
 *	PPP.15	09-90	 [ks]	improve mbuf handling
 *	PPP.16	11-02	 [karn]	substantially rewritten to use NOS facilities
 *
 *	- Feb 1991	[email protected]
 *			variable number of conversation slots
 *			allow zero or one slots
 *			separate routines
 *			status display
 *	- Jul 1994	Dmitry Gorodchanin
 *			Fixes for memory leaks.
 *      - Oct 1994      Dmitry Gorodchanin
 *                      Modularization.
 *	- Jan 1995	Bjorn Ekwall
 *			Use ip_fast_csum from ip.h
 *	- July 1995	Christos A. Polyzols
 *			Spotted bug in tcp option checking
 *
 *
 *	This module is a difficult issue. It's clearly inet code but it's also clearly
 *	driver code belonging close to PPP and SLIP
 */

#include <linux/module.h>
#include <linux/slab.h>
#include <linux/types.h>
#include <linux/string.h>
#include <linux/errno.h>
#include <linux/kernel.h>
#include <net/slhc_vj.h>

#ifdef CONFIG_INET
/* Entire module is for IP only */
#include <linux/mm.h>
#include <linux/socket.h>
#include <linux/sockios.h>
#include <linux/termios.h>
#include <linux/in.h>
#include <linux/fcntl.h>
#include <linux/inet.h>
#include <linux/netdevice.h>
#include <net/ip.h>
#include <net/protocol.h>
#include <net/icmp.h>
#include <net/tcp.h>
#include <linux/skbuff.h>
#include <net/sock.h>
#include <linux/timer.h>
#include <linux/uaccess.h>
#include <net/checksum.h>
#include <asm/unaligned.h>

static unsigned char *encode(unsigned char *cp, unsigned short n);
static long decode(unsigned char **cpp);
static unsigned char * put16(unsigned char *cp, unsigned short x);
static unsigned short pull16(unsigned char **cpp);

/* Allocate compression data structure
 *	slots must be in range 0 to 255 (zero meaning no compression)
 * Returns pointer to structure or ERR_PTR() on error.
 */
struct slcompress *
slhc_init(int rslots, int tslots)
{ … }


/* Free a compression data structure */
void
slhc_free(struct slcompress *comp)
{ … }


/* Put a short in host order into a char array in network order */
static inline unsigned char *
put16(unsigned char *cp, unsigned short x)
{ … }


/* Encode a number */
static unsigned char *
encode(unsigned char *cp, unsigned short n)
{ … }

/* Pull a 16-bit integer in host order from buffer in network byte order */
static unsigned short
pull16(unsigned char **cpp)
{ … }

/* Decode a number */
static long
decode(unsigned char **cpp)
{ … }

/*
 * icp and isize are the original packet.
 * ocp is a place to put a copy if necessary.
 * cpp is initially a pointer to icp.  If the copy is used,
 *    change it to ocp.
 */

int
slhc_compress(struct slcompress *comp, unsigned char *icp, int isize,
	unsigned char *ocp, unsigned char **cpp, int compress_cid)
{ … }


int
slhc_uncompress(struct slcompress *comp, unsigned char *icp, int isize)
{ … }


int
slhc_remember(struct slcompress *comp, unsigned char *icp, int isize)
{ … }

int
slhc_toss(struct slcompress *comp)
{ … }

#else /* CONFIG_INET */

int
slhc_toss(struct slcompress *comp)
{
  printk(KERN_DEBUG "Called IP function on non IP-system: slhc_toss");
  return -EINVAL;
}
int
slhc_uncompress(struct slcompress *comp, unsigned char *icp, int isize)
{
  printk(KERN_DEBUG "Called IP function on non IP-system: slhc_uncompress");
  return -EINVAL;
}
int
slhc_compress(struct slcompress *comp, unsigned char *icp, int isize,
	unsigned char *ocp, unsigned char **cpp, int compress_cid)
{
  printk(KERN_DEBUG "Called IP function on non IP-system: slhc_compress");
  return -EINVAL;
}

int
slhc_remember(struct slcompress *comp, unsigned char *icp, int isize)
{
  printk(KERN_DEBUG "Called IP function on non IP-system: slhc_remember");
  return -EINVAL;
}

void
slhc_free(struct slcompress *comp)
{
  printk(KERN_DEBUG "Called IP function on non IP-system: slhc_free");
}
struct slcompress *
slhc_init(int rslots, int tslots)
{
  printk(KERN_DEBUG "Called IP function on non IP-system: slhc_init");
  return NULL;
}

#endif /* CONFIG_INET */

/* VJ header compression */
EXPORT_SYMBOL(…);
EXPORT_SYMBOL(…);
EXPORT_SYMBOL(…);
EXPORT_SYMBOL(…);
EXPORT_SYMBOL(…);
EXPORT_SYMBOL(…);

MODULE_DESCRIPTION(…) …;
MODULE_LICENSE(…) …;