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|
/*
* 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 (van@helios.ee.lbl.gov), Dec 31, 1989:
* - Initial distribution.
*
*
* modified for KA9Q Internet Software Package by
* Katie Stevens (dkstevens@ucdavis.edu)
* 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 Bill_Simpson@um.cc.umich.edu
* 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 <asm/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)
{
register short i;
register struct cstate *ts;
struct slcompress *comp;
if (rslots < 0 || rslots > 255 || tslots < 0 || tslots > 255)
return ERR_PTR(-EINVAL);
comp = kzalloc(sizeof(struct slcompress), GFP_KERNEL);
if (! comp)
goto out_fail;
if (rslots > 0) {
size_t rsize = rslots * sizeof(struct cstate);
comp->rstate = kzalloc(rsize, GFP_KERNEL);
if (! comp->rstate)
goto out_free;
comp->rslot_limit = rslots - 1;
}
if (tslots > 0) {
size_t tsize = tslots * sizeof(struct cstate);
comp->tstate = kzalloc(tsize, GFP_KERNEL);
if (! comp->tstate)
goto out_free2;
comp->tslot_limit = tslots - 1;
}
comp->xmit_oldest = 0;
comp->xmit_current = 255;
comp->recv_current = 255;
/*
* don't accept any packets with implicit index until we get
* one with an explicit index. Otherwise the uncompress code
* will try to use connection 255, which is almost certainly
* out of range
*/
comp->flags |= SLF_TOSS;
if ( tslots > 0 ) {
ts = comp->tstate;
for(i = comp->tslot_limit; i > 0; --i){
ts[i].cs_this = i;
ts[i].next = &(ts[i - 1]);
}
ts[0].next = &(ts[comp->tslot_limit]);
ts[0].cs_this = 0;
}
return comp;
out_free2:
kfree(comp->rstate);
out_free:
kfree(comp);
out_fail:
return ERR_PTR(-ENOMEM);
}
/* Free a compression data structure */
void
slhc_free(struct slcompress *comp)
{
if ( comp == NULLSLCOMPR )
return;
if ( comp->tstate != NULLSLSTATE )
kfree( comp->tstate );
if ( comp->rstate != NULLSLSTATE )
kfree( comp->rstate );
kfree( 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)
{
*cp++ = x >> 8;
*cp++ = x;
return cp;
}
/* Encode a number */
static unsigned char *
encode(unsigned char *cp, unsigned short n)
{
if(n >= 256 || n == 0){
*cp++ = 0;
cp = put16(cp,n);
} else {
*cp++ = n;
}
return cp;
}
/* Pull a 16-bit integer in host order from buffer in network byte order */
static unsigned short
pull16(unsigned char **cpp)
{
short rval;
rval = *(*cpp)++;
rval <<= 8;
rval |= *(*cpp)++;
return rval;
}
/* Decode a number */
static long
decode(unsigned char **cpp)
{
register int x;
x = *(*cpp)++;
if(x == 0){
return pull16(cpp) & 0xffff; /* pull16 returns -1 on error */
} else {
return x & 0xff; /* -1 if PULLCHAR returned error */
}
}
/*
* 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)
{
register struct cstate *ocs = &(comp->tstate[comp->xmit_oldest]);
register struct cstate *lcs = ocs;
register struct cstate
|