freebsd-dev/usr.sbin/ppp/pred.c
1997-12-21 12:11:13 +00:00

342 lines
7.9 KiB
C

/*-
* Copyright (c) 1997 Brian Somers <brian@Awfulhak.org>
* Ian Donaldson <iand@labtam.labtam.oz.au>
* Carsten Bormann <cabo@cs.tu-berlin.de>
* Dave Rand <dlr@bungi.com>/<dave_rand@novell.com>
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*
* $Id$
*/
#include <sys/param.h>
#include <netinet/in.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include "command.h"
#include "mbuf.h"
#include "log.h"
#include "defs.h"
#include "loadalias.h"
#include "vars.h"
#include "timer.h"
#include "fsm.h"
#include "hdlc.h"
#include "lcpproto.h"
#include "lcp.h"
#include "ccp.h"
#include "pred.h"
/* The following hash code is the heart of the algorithm:
* It builds a sliding hash sum of the previous 3-and-a-bit characters
* which will be used to index the guess table.
* A better hash function would result in additional compression,
* at the expense of time.
*/
#define IHASH(x) do {iHash = (iHash << 4) ^ (x);} while(0)
#define OHASH(x) do {oHash = (oHash << 4) ^ (x);} while(0)
#define GUESS_TABLE_SIZE 65536
static unsigned short int iHash, oHash;
static unsigned char *InputGuessTable;
static unsigned char *OutputGuessTable;
static int
compress(u_char * source, u_char * dest, int len)
{
int i, bitmask;
unsigned char *flagdest, flags, *orgdest;
orgdest = dest;
while (len) {
flagdest = dest++;
flags = 0; /* All guess wrong initially */
for (bitmask = 1, i = 0; i < 8 && len; i++, bitmask <<= 1) {
if (OutputGuessTable[oHash] == *source) {
flags |= bitmask; /* Guess was right - don't output */
} else {
OutputGuessTable[oHash] = *source;
*dest++ = *source; /* Guess wrong, output char */
}
OHASH(*source++);
len--;
}
*flagdest = flags;
}
return (dest - orgdest);
}
static void
SyncTable(u_char * source, u_char * dest, int len)
{
while (len--) {
if (InputGuessTable[iHash] != *source) {
InputGuessTable[iHash] = *source;
}
IHASH(*dest++ = *source++);
}
}
static int
decompress(u_char * source, u_char * dest, int len)
{
int i, bitmask;
unsigned char flags, *orgdest;
orgdest = dest;
while (len) {
flags = *source++;
len--;
for (i = 0, bitmask = 1; i < 8; i++, bitmask <<= 1) {
if (flags & bitmask) {
*dest = InputGuessTable[iHash]; /* Guess correct */
} else {
if (!len)
break; /* we seem to be really done -- cabo */
InputGuessTable[iHash] = *source; /* Guess wrong */
*dest = *source++; /* Read from source */
len--;
}
IHASH(*dest++);
}
}
return (dest - orgdest);
}
static void
Pred1TermInput(void)
{
if (InputGuessTable != NULL) {
free(InputGuessTable);
InputGuessTable = NULL;
}
}
static void
Pred1TermOutput(void)
{
if (OutputGuessTable != NULL) {
free(OutputGuessTable);
OutputGuessTable = NULL;
}
}
static void
Pred1ResetInput(void)
{
iHash = 0;
memset(InputGuessTable, '\0', GUESS_TABLE_SIZE);
LogPrintf(LogCCP, "Predictor1: Input channel reset\n");
}
static void
Pred1ResetOutput(void)
{
oHash = 0;
memset(OutputGuessTable, '\0', GUESS_TABLE_SIZE);
LogPrintf(LogCCP, "Predictor1: Output channel reset\n");
}
static int
Pred1InitInput(void)
{
if (InputGuessTable == NULL)
if ((InputGuessTable = malloc(GUESS_TABLE_SIZE)) == NULL)
return 0;
Pred1ResetInput();
return 1;
}
static int
Pred1InitOutput(void)
{
if (OutputGuessTable == NULL)
if ((OutputGuessTable = malloc(GUESS_TABLE_SIZE)) == NULL)
return 0;
Pred1ResetOutput();
return 1;
}
static int
Pred1Output(int pri, u_short proto, struct mbuf * bp)
{
struct mbuf *mwp;
u_char *cp, *wp, *hp;
int orglen, len;
u_char bufp[MAX_MTU + 2];
u_short fcs;
orglen = plength(bp) + 2; /* add count of proto */
mwp = mballoc((orglen + 2) / 8 * 9 + 12, MB_HDLCOUT);
hp = wp = MBUF_CTOP(mwp);
cp = bufp;
*wp++ = *cp++ = orglen >> 8;
*wp++ = *cp++ = orglen & 0377;
*cp++ = proto >> 8;
*cp++ = proto & 0377;
mbread(bp, cp, orglen - 2);
fcs = HdlcFcs(INITFCS, bufp, 2 + orglen);
fcs = ~fcs;
len = compress(bufp + 2, wp, orglen);
LogPrintf(LogDEBUG, "Pred1Output: orglen (%d) --> len (%d)\n", orglen, len);
CcpInfo.uncompout += orglen;
if (len < orglen) {
*hp |= 0x80;
wp += len;
CcpInfo.compout += len;
} else {
memcpy(wp, bufp + 2, orglen);
wp += orglen;
CcpInfo.compout += orglen;
}
*wp++ = fcs & 0377;
*wp++ = fcs >> 8;
mwp->cnt = wp - MBUF_CTOP(mwp);
HdlcOutput(PRI_NORMAL, PROTO_COMPD, mwp);
return 1;
}
static struct mbuf *
Pred1Input(u_short *proto, struct mbuf *bp)
{
u_char *cp, *pp;
int len, olen, len1;
struct mbuf *wp;
u_char *bufp;
u_short fcs;
wp = mballoc(MAX_MTU + 2, MB_IPIN);
cp = MBUF_CTOP(bp);
olen = plength(bp);
pp = bufp = MBUF_CTOP(wp);
*pp++ = *cp & 0177;
len = *cp++ << 8;
*pp++ = *cp;
len += *cp++;
CcpInfo.uncompin += len & 0x7fff;
if (len & 0x8000) {
len1 = decompress(cp, pp, olen - 4);
CcpInfo.compin += olen;
len &= 0x7fff;
if (len != len1) { /* Error is detected. Send reset request */
LogPrintf(LogCCP, "Pred1: Length error\n");
CcpSendResetReq(&CcpFsm);
pfree(bp);
pfree(wp);
return NULL;
}
cp += olen - 4;
pp += len1;
} else {
CcpInfo.compin += len;
SyncTable(cp, pp, len);
cp += len;
pp += len;
}
*pp++ = *cp++; /* CRC */
*pp++ = *cp++;
fcs = HdlcFcs(INITFCS, bufp, wp->cnt = pp - bufp);
if (fcs != GOODFCS)
LogPrintf(LogDEBUG, "Pred1Input: fcs = 0x%04x (%s), len = 0x%x,"
" olen = 0x%x\n", fcs, (fcs == GOODFCS) ? "good" : "bad",
len, olen);
if (fcs == GOODFCS) {
wp->offset += 2; /* skip length */
wp->cnt -= 4; /* skip length & CRC */
pp = MBUF_CTOP(wp);
*proto = *pp++;
if (*proto & 1) {
wp->offset++;
wp->cnt--;
} else {
wp->offset += 2;
wp->cnt -= 2;
*proto = (*proto << 8) | *pp++;
}
return wp;
} else {
LogDumpBp(LogHDLC, "Bad FCS", wp);
CcpSendResetReq(&CcpFsm);
pfree(wp);
}
pfree(bp);
return NULL;
}
static void
Pred1DictSetup(u_short proto, struct mbuf * bp)
{
}
static const char *
Pred1DispOpts(struct lcp_opt *o)
{
return NULL;
}
static void
Pred1GetOpts(struct lcp_opt *o)
{
o->id = TY_PRED1;
o->len = 2;
}
static int
Pred1SetOpts(struct lcp_opt *o)
{
if (o->id != TY_PRED1 || o->len != 2) {
Pred1GetOpts(o);
return MODE_NAK;
}
return MODE_ACK;
}
const struct ccp_algorithm Pred1Algorithm = {
TY_PRED1,
ConfPred1,
Pred1DispOpts,
{
Pred1GetOpts,
Pred1SetOpts,
Pred1InitInput,
Pred1TermInput,
Pred1ResetInput,
Pred1Input,
Pred1DictSetup
},
{
Pred1GetOpts,
Pred1SetOpts,
Pred1InitOutput,
Pred1TermOutput,
Pred1ResetOutput,
Pred1Output
},
};