patch-2.2.11 linux/drivers/isdn/isdn_bsdcomp.c
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- Lines: 935
- Date:
Mon Aug 9 12:04:39 1999
- Orig file:
v2.2.10/linux/drivers/isdn/isdn_bsdcomp.c
- Orig date:
Wed Dec 31 16:00:00 1969
diff -u --recursive --new-file v2.2.10/linux/drivers/isdn/isdn_bsdcomp.c linux/drivers/isdn/isdn_bsdcomp.c
@@ -0,0 +1,934 @@
+/*
+ * BSD compression module
+ *
+ * Patched version for ISDN syncPPP written 1997/1998 by Michael Hipp
+ * The whole module is now SKB based.
+ *
+ * Compile with:
+ * gcc -O2 -I/usr/src/linux/include -D__KERNEL__ -DMODULE -c isdn_bsdcomp.c
+ */
+
+/*
+ * Original copyright notice:
+ *
+ * Copyright (c) 1985, 1986 The Regents of the University of California.
+ * All rights reserved.
+ *
+ * This code is derived from software contributed to Berkeley by
+ * James A. Woods, derived from original work by Spencer Thomas
+ * and Joseph Orost.
+ *
+ * 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.
+ * 3. All advertising materials mentioning features or use of this software
+ * must display the following acknowledgement:
+ * This product includes software developed by the University of
+ * California, Berkeley and its contributors.
+ * 4. Neither the name of the University nor the names of its contributors
+ * may be used to endorse or promote products derived from this software
+ * without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE REGENTS 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 REGENTS 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.
+ */
+
+#ifndef MODULE
+#error This file must be compiled as a module.
+#endif
+
+#include <linux/module.h>
+
+#include <linux/kernel.h>
+#include <linux/sched.h>
+#include <linux/types.h>
+#include <linux/fcntl.h>
+#include <linux/interrupt.h>
+#include <linux/ptrace.h>
+#include <linux/ioport.h>
+#include <linux/in.h>
+#include <linux/malloc.h>
+#include <linux/tty.h>
+#include <linux/errno.h>
+#include <linux/sched.h> /* to get the struct task_struct */
+#include <linux/string.h> /* used in new tty drivers */
+#include <linux/signal.h> /* used in new tty drivers */
+
+#include <asm/system.h>
+#include <asm/bitops.h>
+#include <asm/segment.h>
+#include <asm/byteorder.h>
+#include <asm/types.h>
+
+#include <linux/if.h>
+
+#include <linux/if_ether.h>
+#include <linux/netdevice.h>
+#include <linux/skbuff.h>
+#include <linux/inet.h>
+#include <linux/ioctl.h>
+
+#include <linux/ppp_defs.h>
+
+#include <linux/isdn.h>
+#include <linux/isdn_ppp.h>
+/* #include <linux/netprotocol.h> */
+#include <linux/ip.h>
+#include <linux/tcp.h>
+#include <linux/if_arp.h>
+#include <linux/ppp-comp.h>
+
+#include "isdn_ppp.h"
+
+#define BSD_VERSION(x) ((x) >> 5)
+#define BSD_NBITS(x) ((x) & 0x1F)
+
+#define BSD_CURRENT_VERSION 1
+
+#define DEBUG 1
+
+/*
+ * A dictionary for doing BSD compress.
+ */
+
+struct bsd_dict {
+ u32 fcode;
+ u16 codem1; /* output of hash table -1 */
+ u16 cptr; /* map code to hash table entry */
+};
+
+struct bsd_db {
+ int totlen; /* length of this structure */
+ unsigned int hsize; /* size of the hash table */
+ unsigned char hshift; /* used in hash function */
+ unsigned char n_bits; /* current bits/code */
+ unsigned char maxbits; /* maximum bits/code */
+ unsigned char debug; /* non-zero if debug desired */
+ unsigned char unit; /* ppp unit number */
+ u16 seqno; /* sequence # of next packet */
+ unsigned int mru; /* size of receive (decompress) bufr */
+ unsigned int maxmaxcode; /* largest valid code */
+ unsigned int max_ent; /* largest code in use */
+ unsigned int in_count; /* uncompressed bytes, aged */
+ unsigned int bytes_out; /* compressed bytes, aged */
+ unsigned int ratio; /* recent compression ratio */
+ unsigned int checkpoint; /* when to next check the ratio */
+ unsigned int clear_count; /* times dictionary cleared */
+ unsigned int incomp_count; /* incompressible packets */
+ unsigned int incomp_bytes; /* incompressible bytes */
+ unsigned int uncomp_count; /* uncompressed packets */
+ unsigned int uncomp_bytes; /* uncompressed bytes */
+ unsigned int comp_count; /* compressed packets */
+ unsigned int comp_bytes; /* compressed bytes */
+ unsigned short *lens; /* array of lengths of codes */
+ struct bsd_dict *dict; /* dictionary */
+ int xmit;
+};
+
+#define BSD_OVHD 2 /* BSD compress overhead/packet */
+#define MIN_BSD_BITS 9
+#define BSD_INIT_BITS MIN_BSD_BITS
+#define MAX_BSD_BITS 15
+
+/*
+ * the next two codes should not be changed lightly, as they must not
+ * lie within the contiguous general code space.
+ */
+#define CLEAR 256 /* table clear output code */
+#define FIRST 257 /* first free entry */
+#define LAST 255
+
+#define MAXCODE(b) ((1 << (b)) - 1)
+#define BADCODEM1 MAXCODE(MAX_BSD_BITS);
+
+#define BSD_HASH(prefix,suffix,hshift) ((((unsigned long)(suffix))<<(hshift)) \
+ ^ (unsigned long)(prefix))
+#define BSD_KEY(prefix,suffix) ((((unsigned long)(suffix)) << 16) \
+ + (unsigned long)(prefix))
+
+#define CHECK_GAP 10000 /* Ratio check interval */
+
+#define RATIO_SCALE_LOG 8
+#define RATIO_SCALE (1<<RATIO_SCALE_LOG)
+#define RATIO_MAX (0x7fffffff>>RATIO_SCALE_LOG)
+
+/*
+ * clear the dictionary
+ */
+
+static void bsd_clear(struct bsd_db *db)
+{
+ db->clear_count++;
+ db->max_ent = FIRST-1;
+ db->n_bits = BSD_INIT_BITS;
+ db->bytes_out = 0;
+ db->in_count = 0;
+ db->incomp_count = 0;
+ db->ratio = 0;
+ db->checkpoint = CHECK_GAP;
+}
+
+/*
+ * If the dictionary is full, then see if it is time to reset it.
+ *
+ * Compute the compression ratio using fixed-point arithmetic
+ * with 8 fractional bits.
+ *
+ * Since we have an infinite stream instead of a single file,
+ * watch only the local compression ratio.
+ *
+ * Since both peers must reset the dictionary at the same time even in
+ * the absence of CLEAR codes (while packets are incompressible), they
+ * must compute the same ratio.
+ */
+static int bsd_check (struct bsd_db *db) /* 1=output CLEAR */
+{
+ unsigned int new_ratio;
+
+ if (db->in_count >= db->checkpoint)
+ {
+ /* age the ratio by limiting the size of the counts */
+ if (db->in_count >= RATIO_MAX || db->bytes_out >= RATIO_MAX)
+ {
+ db->in_count -= (db->in_count >> 2);
+ db->bytes_out -= (db->bytes_out >> 2);
+ }
+
+ db->checkpoint = db->in_count + CHECK_GAP;
+
+ if (db->max_ent >= db->maxmaxcode)
+ {
+ /* Reset the dictionary only if the ratio is worse,
+ * or if it looks as if it has been poisoned
+ * by incompressible data.
+ *
+ * This does not overflow, because
+ * db->in_count <= RATIO_MAX.
+ */
+
+ new_ratio = db->in_count << RATIO_SCALE_LOG;
+ if (db->bytes_out != 0)
+ {
+ new_ratio /= db->bytes_out;
+ }
+
+ if (new_ratio < db->ratio || new_ratio < 1 * RATIO_SCALE)
+ {
+ bsd_clear (db);
+ return 1;
+ }
+ db->ratio = new_ratio;
+ }
+ }
+ return 0;
+}
+
+/*
+ * Return statistics.
+ */
+
+static void bsd_stats (void *state, struct compstat *stats)
+{
+ struct bsd_db *db = (struct bsd_db *) state;
+
+ stats->unc_bytes = db->uncomp_bytes;
+ stats->unc_packets = db->uncomp_count;
+ stats->comp_bytes = db->comp_bytes;
+ stats->comp_packets = db->comp_count;
+ stats->inc_bytes = db->incomp_bytes;
+ stats->inc_packets = db->incomp_count;
+ stats->in_count = db->in_count;
+ stats->bytes_out = db->bytes_out;
+}
+
+/*
+ * Reset state, as on a CCP ResetReq.
+ */
+static void bsd_reset (void *state,unsigned char code, unsigned char id,
+ unsigned char *data, unsigned len,
+ struct isdn_ppp_resetparams *rsparm)
+{
+ struct bsd_db *db = (struct bsd_db *) state;
+
+ bsd_clear(db);
+ db->seqno = 0;
+ db->clear_count = 0;
+}
+
+/*
+ * Release the compression structure
+ */
+static void bsd_free (void *state)
+{
+ struct bsd_db *db = (struct bsd_db *) state;
+
+ if (db) {
+ /*
+ * Release the dictionary
+ */
+ if (db->dict) {
+ vfree (db->dict);
+ db->dict = NULL;
+ }
+
+ /*
+ * Release the string buffer
+ */
+ if (db->lens) {
+ vfree (db->lens);
+ db->lens = NULL;
+ }
+
+ /*
+ * Finally release the structure itself.
+ */
+ kfree (db);
+ MOD_DEC_USE_COUNT;
+ }
+}
+
+
+/*
+ * Allocate space for a (de) compressor.
+ */
+static void *bsd_alloc (struct isdn_ppp_comp_data *data)
+{
+ int bits;
+ unsigned int hsize, hshift, maxmaxcode;
+ struct bsd_db *db;
+ int decomp;
+
+ static unsigned int htab[][2] = {
+ { 5003 , 4 } , { 5003 , 4 } , { 5003 , 4 } , { 5003 , 4 } ,
+ { 9001 , 5 } , { 18013 , 6 } , { 35023 , 7 } , { 69001 , 8 }
+ };
+
+ if (data->optlen != 1 || data->num != CI_BSD_COMPRESS
+ || BSD_VERSION(data->options[0]) != BSD_CURRENT_VERSION)
+ return NULL;
+
+ bits = BSD_NBITS(data->options[0]);
+
+ if(bits < 9 || bits > 15)
+ return NULL;
+
+ hsize = htab[bits-9][0];
+ hshift = htab[bits-9][1];
+
+ /*
+ * Allocate the main control structure for this instance.
+ */
+ maxmaxcode = MAXCODE(bits);
+ db = (struct bsd_db *) kmalloc (sizeof (struct bsd_db),GFP_KERNEL);
+ if (!db)
+ return NULL;
+
+ memset (db, 0, sizeof(struct bsd_db));
+
+ db->xmit = data->flags & IPPP_COMP_FLAG_XMIT;
+ decomp = db->xmit ? 0 : 1;
+
+ /*
+ * Allocate space for the dictionary. This may be more than one page in
+ * length.
+ */
+ db->dict = (struct bsd_dict *) vmalloc (hsize * sizeof (struct bsd_dict));
+ if (!db->dict) {
+ bsd_free (db);
+ return NULL;
+ }
+
+ MOD_INC_USE_COUNT;
+
+ /*
+ * If this is the compression buffer then there is no length data.
+ * For decompression, the length information is needed as well.
+ */
+ if (!decomp)
+ db->lens = NULL;
+ else {
+ db->lens = (unsigned short *) vmalloc ((maxmaxcode + 1) *
+ sizeof (db->lens[0]));
+ if (!db->lens) {
+ bsd_free (db); /* calls MOD_DEC_USE_COUNT; */
+ return (NULL);
+ }
+ }
+
+ /*
+ * Initialize the data information for the compression code
+ */
+ db->totlen = sizeof (struct bsd_db) + (sizeof (struct bsd_dict) * hsize);
+ db->hsize = hsize;
+ db->hshift = hshift;
+ db->maxmaxcode = maxmaxcode;
+ db->maxbits = bits;
+
+ return (void *) db;
+}
+
+/*
+ * Initialize the database.
+ */
+static int bsd_init (void *state, struct isdn_ppp_comp_data *data, int unit, int debug)
+{
+ struct bsd_db *db = state;
+ int indx;
+ int decomp;
+
+ if(!state || !data) {
+ printk(KERN_ERR "isdn_bsd_init: [%d] ERR, state %lx data %lx\n",unit,(long)state,(long)data);
+ return 0;
+ }
+
+ decomp = db->xmit ? 0 : 1;
+
+ if (data->optlen != 1 || data->num != CI_BSD_COMPRESS
+ || (BSD_VERSION(data->options[0]) != BSD_CURRENT_VERSION)
+ || (BSD_NBITS(data->options[0]) != db->maxbits)
+ || (decomp && db->lens == NULL)) {
+ printk(KERN_ERR "isdn_bsd: %d %d %d %d %lx\n",data->optlen,data->num,data->options[0],decomp,(unsigned long)db->lens);
+ return 0;
+ }
+
+ if (decomp)
+ for(indx=LAST;indx>=0;indx--)
+ db->lens[indx] = 1;
+
+ indx = db->hsize;
+ while (indx-- != 0) {
+ db->dict[indx].codem1 = BADCODEM1;
+ db->dict[indx].cptr = 0;
+ }
+
+ db->unit = unit;
+ db->mru = 0;
+
+ db->debug = 1;
+
+ bsd_reset(db,0,0,NULL,0,NULL);
+
+ return 1;
+}
+
+/*
+ * Obtain pointers to the various structures in the compression tables
+ */
+
+#define dict_ptrx(p,idx) &(p->dict[idx])
+#define lens_ptrx(p,idx) &(p->lens[idx])
+
+#ifdef DEBUG
+static unsigned short *lens_ptr(struct bsd_db *db, int idx)
+{
+ if ((unsigned int) idx > (unsigned int) db->maxmaxcode) {
+ printk (KERN_DEBUG "<9>ppp: lens_ptr(%d) > max\n", idx);
+ idx = 0;
+ }
+ return lens_ptrx (db, idx);
+}
+
+static struct bsd_dict *dict_ptr(struct bsd_db *db, int idx)
+{
+ if ((unsigned int) idx >= (unsigned int) db->hsize) {
+ printk (KERN_DEBUG "<9>ppp: dict_ptr(%d) > max\n", idx);
+ idx = 0;
+ }
+ return dict_ptrx (db, idx);
+}
+
+#else
+#define lens_ptr(db,idx) lens_ptrx(db,idx)
+#define dict_ptr(db,idx) dict_ptrx(db,idx)
+#endif
+
+/*
+ * compress a packet
+ */
+static int bsd_compress (void *state, struct sk_buff *skb_in, struct sk_buff *skb_out,int proto)
+{
+ struct bsd_db *db;
+ int hshift;
+ unsigned int max_ent;
+ unsigned int n_bits;
+ unsigned int bitno;
+ unsigned long accm;
+ int ent;
+ unsigned long fcode;
+ struct bsd_dict *dictp;
+ unsigned char c;
+ int hval,disp,ilen,mxcode;
+ unsigned char *rptr = skb_in->data;
+ int isize = skb_in->len;
+
+#define OUTPUT(ent) \
+ { \
+ bitno -= n_bits; \
+ accm |= ((ent) << bitno); \
+ do { \
+ if(skb_out && skb_tailroom(skb_out) > 0) \
+ *(skb_put(skb_out,1)) = (unsigned char) (accm>>24); \
+ accm <<= 8; \
+ bitno += 8; \
+ } while (bitno <= 24); \
+ }
+
+ /*
+ * If the protocol is not in the range we're interested in,
+ * just return without compressing the packet. If it is,
+ * the protocol becomes the first byte to compress.
+ */
+ printk(KERN_DEBUG "bsd_compress called with %x\n",proto);
+
+ ent = proto;
+ if (proto < 0x21 || proto > 0xf9 || !(proto & 0x1) )
+ return 0;
+
+ db = (struct bsd_db *) state;
+ hshift = db->hshift;
+ max_ent = db->max_ent;
+ n_bits = db->n_bits;
+ bitno = 32;
+ accm = 0;
+ mxcode = MAXCODE (n_bits);
+
+ /* This is the PPP header information */
+ if(skb_out && skb_tailroom(skb_out) >= 2) {
+ char *v = skb_put(skb_out,2);
+ /* we only push our own data on the header,
+ AC,PC and protos is pushed by caller */
+ v[0] = db->seqno >> 8;
+ v[1] = db->seqno;
+ }
+
+ ilen = ++isize; /* This is off by one, but that is what is in draft! */
+
+ while (--ilen > 0) {
+ c = *rptr++;
+ fcode = BSD_KEY (ent, c);
+ hval = BSD_HASH (ent, c, hshift);
+ dictp = dict_ptr (db, hval);
+
+ /* Validate and then check the entry. */
+ if (dictp->codem1 >= max_ent)
+ goto nomatch;
+
+ if (dictp->fcode == fcode) {
+ ent = dictp->codem1 + 1;
+ continue; /* found (prefix,suffix) */
+ }
+
+ /* continue probing until a match or invalid entry */
+ disp = (hval == 0) ? 1 : hval;
+
+ do {
+ hval += disp;
+ if (hval >= db->hsize)
+ hval -= db->hsize;
+ dictp = dict_ptr (db, hval);
+ if (dictp->codem1 >= max_ent)
+ goto nomatch;
+ } while (dictp->fcode != fcode);
+
+ ent = dictp->codem1 + 1; /* finally found (prefix,suffix) */
+ continue;
+
+nomatch:
+ OUTPUT(ent); /* output the prefix */
+
+ /* code -> hashtable */
+ if (max_ent < db->maxmaxcode) {
+ struct bsd_dict *dictp2;
+ struct bsd_dict *dictp3;
+ int indx;
+
+ /* expand code size if needed */
+ if (max_ent >= mxcode) {
+ db->n_bits = ++n_bits;
+ mxcode = MAXCODE (n_bits);
+ }
+
+ /*
+ * Invalidate old hash table entry using
+ * this code, and then take it over.
+ */
+ dictp2 = dict_ptr (db, max_ent + 1);
+ indx = dictp2->cptr;
+ dictp3 = dict_ptr (db, indx);
+
+ if (dictp3->codem1 == max_ent)
+ dictp3->codem1 = BADCODEM1;
+
+ dictp2->cptr = hval;
+ dictp->codem1 = max_ent;
+ dictp->fcode = fcode;
+ db->max_ent = ++max_ent;
+
+ if (db->lens) {
+ unsigned short *len1 = lens_ptr (db, max_ent);
+ unsigned short *len2 = lens_ptr (db, ent);
+ *len1 = *len2 + 1;
+ }
+ }
+ ent = c;
+ }
+
+ OUTPUT(ent); /* output the last code */
+
+ if(skb_out)
+ db->bytes_out += skb_out->len; /* Do not count bytes from here */
+ db->uncomp_bytes += isize;
+ db->in_count += isize;
+ ++db->uncomp_count;
+ ++db->seqno;
+
+ if (bitno < 32)
+ ++db->bytes_out; /* must be set before calling bsd_check */
+
+ /*
+ * Generate the clear command if needed
+ */
+
+ if (bsd_check(db))
+ OUTPUT (CLEAR);
+
+ /*
+ * Pad dribble bits of last code with ones.
+ * Do not emit a completely useless byte of ones.
+ */
+ if (bitno < 32 && skb_out && skb_tailroom(skb_out) > 0)
+ *(skb_put(skb_out,1)) = (unsigned char) ((accm | (0xff << (bitno-8))) >> 24);
+
+ /*
+ * Increase code size if we would have without the packet
+ * boundary because the decompressor will do so.
+ */
+ if (max_ent >= mxcode && max_ent < db->maxmaxcode)
+ db->n_bits++;
+
+ /* If output length is too large then this is an incompressible frame. */
+ if (!skb_out || (skb_out && skb_out->len >= skb_in->len) ) {
+ ++db->incomp_count;
+ db->incomp_bytes += isize;
+ return 0;
+ }
+
+ /* Count the number of compressed frames */
+ ++db->comp_count;
+ db->comp_bytes += skb_out->len;
+ return skb_out->len;
+
+#undef OUTPUT
+}
+
+/*
+ * Update the "BSD Compress" dictionary on the receiver for
+ * incompressible data by pretending to compress the incoming data.
+ */
+static void bsd_incomp (void *state, struct sk_buff *skb_in,int proto)
+{
+ bsd_compress (state, skb_in, NULL, proto);
+}
+
+/*
+ * Decompress "BSD Compress".
+ */
+static int bsd_decompress (void *state, struct sk_buff *skb_in, struct sk_buff *skb_out,
+ struct isdn_ppp_resetparams *rsparm)
+{
+ struct bsd_db *db;
+ unsigned int max_ent;
+ unsigned long accm;
+ unsigned int bitno; /* 1st valid bit in accm */
+ unsigned int n_bits;
+ unsigned int tgtbitno; /* bitno when we have a code */
+ struct bsd_dict *dictp;
+ int seq;
+ unsigned int incode;
+ unsigned int oldcode;
+ unsigned int finchar;
+ unsigned char *p,*ibuf;
+ int ilen;
+ int codelen;
+ int extra;
+
+ db = (struct bsd_db *) state;
+ max_ent = db->max_ent;
+ accm = 0;
+ bitno = 32; /* 1st valid bit in accm */
+ n_bits = db->n_bits;
+ tgtbitno = 32 - n_bits; /* bitno when we have a code */
+
+ printk(KERN_DEBUG "bsd_decompress called\n");
+
+ if(!skb_in || !skb_out) {
+ printk(KERN_ERR "bsd_decompress called with NULL parameter\n");
+ return DECOMP_ERROR;
+ }
+
+ /*
+ * Get the sequence number.
+ */
+ if( (p = skb_pull(skb_in,2)) == NULL) {
+ return DECOMP_ERROR;
+ }
+ p-=2;
+ seq = (p[0] << 8) + p[1];
+ ilen = skb_in->len;
+ ibuf = skb_in->data;
+
+ /*
+ * Check the sequence number and give up if it differs from
+ * the value we're expecting.
+ */
+ if (seq != db->seqno) {
+ if (db->debug) {
+ printk(KERN_DEBUG "bsd_decomp%d: bad sequence # %d, expected %d\n",
+ db->unit, seq, db->seqno - 1);
+ }
+ return DECOMP_ERROR;
+ }
+
+ ++db->seqno;
+ db->bytes_out += ilen;
+
+ if(skb_tailroom(skb_out) > 0)
+ *(skb_put(skb_out,1)) = 0;
+ else
+ return DECOMP_ERR_NOMEM;
+
+ oldcode = CLEAR;
+
+ /*
+ * Keep the checkpoint correctly so that incompressible packets
+ * clear the dictionary at the proper times.
+ */
+
+ for (;;) {
+ if (ilen-- <= 0) {
+ db->in_count += (skb_out->len - 1); /* don't count the header */
+ break;
+ }
+
+ /*
+ * Accumulate bytes until we have a complete code.
+ * Then get the next code, relying on the 32-bit,
+ * unsigned accm to mask the result.
+ */
+
+ bitno -= 8;
+ accm |= *ibuf++ << bitno;
+ if (tgtbitno < bitno)
+ continue;
+
+ incode = accm >> tgtbitno;
+ accm <<= n_bits;
+ bitno += n_bits;
+
+ /*
+ * The dictionary must only be cleared at the end of a packet.
+ */
+
+ if (incode == CLEAR) {
+ if (ilen > 0) {
+ if (db->debug)
+ printk(KERN_DEBUG "bsd_decomp%d: bad CLEAR\n", db->unit);
+ return DECOMP_FATALERROR; /* probably a bug */
+ }
+ bsd_clear(db);
+ break;
+ }
+
+ if ((incode > max_ent + 2) || (incode > db->maxmaxcode)
+ || (incode > max_ent && oldcode == CLEAR)) {
+ if (db->debug) {
+ printk(KERN_DEBUG "bsd_decomp%d: bad code 0x%x oldcode=0x%x ",
+ db->unit, incode, oldcode);
+ printk(KERN_DEBUG "max_ent=0x%x skb->Len=%d seqno=%d\n",
+ max_ent, skb_out->len, db->seqno);
+ }
+ return DECOMP_FATALERROR; /* probably a bug */
+ }
+
+ /* Special case for KwKwK string. */
+ if (incode > max_ent) {
+ finchar = oldcode;
+ extra = 1;
+ } else {
+ finchar = incode;
+ extra = 0;
+ }
+
+ codelen = *(lens_ptr (db, finchar));
+ if( skb_tailroom(skb_out) < codelen + extra) {
+ if (db->debug) {
+ printk(KERN_DEBUG "bsd_decomp%d: ran out of mru\n", db->unit);
+#ifdef DEBUG
+ printk(KERN_DEBUG " len=%d, finchar=0x%x, codelen=%d,skblen=%d\n",
+ ilen, finchar, codelen, skb_out->len);
+#endif
+ }
+ return DECOMP_FATALERROR;
+ }
+
+ /*
+ * Decode this code and install it in the decompressed buffer.
+ */
+
+ p = skb_put(skb_out,codelen);
+ p += codelen;
+ while (finchar > LAST) {
+ struct bsd_dict *dictp2 = dict_ptr (db, finchar);
+
+ dictp = dict_ptr (db, dictp2->cptr);
+
+#ifdef DEBUG
+ if (--codelen <= 0 || dictp->codem1 != finchar-1) {
+ if (codelen <= 0) {
+ printk(KERN_ERR "bsd_decomp%d: fell off end of chain ", db->unit);
+ printk(KERN_ERR "0x%x at 0x%x by 0x%x, max_ent=0x%x\n", incode, finchar, dictp2->cptr, max_ent);
+ } else {
+ if (dictp->codem1 != finchar-1) {
+ printk(KERN_ERR "bsd_decomp%d: bad code chain 0x%x finchar=0x%x ",db->unit, incode, finchar);
+ printk(KERN_ERR "oldcode=0x%x cptr=0x%x codem1=0x%x\n", oldcode, dictp2->cptr, dictp->codem1);
+ }
+ }
+ return DECOMP_FATALERROR;
+ }
+#endif
+
+ {
+ u32 fcode = dictp->fcode;
+ *--p = (fcode >> 16) & 0xff;
+ finchar = fcode & 0xffff;
+ }
+ }
+ *--p = finchar;
+
+#ifdef DEBUG
+ if (--codelen != 0)
+ printk(KERN_ERR "bsd_decomp%d: short by %d after code 0x%x, max_ent=0x%x\n", db->unit, codelen, incode, max_ent);
+#endif
+
+ if (extra) /* the KwKwK case again */
+ *(skb_put(skb_out,1)) = finchar;
+
+ /*
+ * If not first code in a packet, and
+ * if not out of code space, then allocate a new code.
+ *
+ * Keep the hash table correct so it can be used
+ * with uncompressed packets.
+ */
+ if (oldcode != CLEAR && max_ent < db->maxmaxcode) {
+ struct bsd_dict *dictp2, *dictp3;
+ u16 *lens1, *lens2;
+ unsigned long fcode;
+ int hval, disp, indx;
+
+ fcode = BSD_KEY(oldcode,finchar);
+ hval = BSD_HASH(oldcode,finchar,db->hshift);
+ dictp = dict_ptr (db, hval);
+
+ /* look for a free hash table entry */
+ if (dictp->codem1 < max_ent) {
+ disp = (hval == 0) ? 1 : hval;
+ do {
+ hval += disp;
+ if (hval >= db->hsize)
+ hval -= db->hsize;
+ dictp = dict_ptr (db, hval);
+ } while (dictp->codem1 < max_ent);
+ }
+
+ /*
+ * Invalidate previous hash table entry
+ * assigned this code, and then take it over
+ */
+
+ dictp2 = dict_ptr (db, max_ent + 1);
+ indx = dictp2->cptr;
+ dictp3 = dict_ptr (db, indx);
+
+ if (dictp3->codem1 == max_ent)
+ dictp3->codem1 = BADCODEM1;
+
+ dictp2->cptr = hval;
+ dictp->codem1 = max_ent;
+ dictp->fcode = fcode;
+ db->max_ent = ++max_ent;
+
+ /* Update the length of this string. */
+ lens1 = lens_ptr (db, max_ent);
+ lens2 = lens_ptr (db, oldcode);
+ *lens1 = *lens2 + 1;
+
+ /* Expand code size if needed. */
+ if (max_ent >= MAXCODE(n_bits) && max_ent < db->maxmaxcode) {
+ db->n_bits = ++n_bits;
+ tgtbitno = 32-n_bits;
+ }
+ }
+ oldcode = incode;
+ }
+
+ ++db->comp_count;
+ ++db->uncomp_count;
+ db->comp_bytes += skb_in->len - BSD_OVHD;
+ db->uncomp_bytes += skb_out->len;
+
+ if (bsd_check(db)) {
+ if (db->debug)
+ printk(KERN_DEBUG "bsd_decomp%d: peer should have cleared dictionary on %d\n",
+ db->unit, db->seqno - 1);
+ }
+ return skb_out->len;
+}
+
+/*************************************************************
+ * Table of addresses for the BSD compression module
+ *************************************************************/
+
+static struct isdn_ppp_compressor ippp_bsd_compress = {
+ NULL,NULL, /* prev,next: overwritten by isdn_ppp */
+ CI_BSD_COMPRESS, /* compress_proto */
+ bsd_alloc, /* alloc */
+ bsd_free, /* free */
+ bsd_init, /* init */
+ bsd_reset, /* reset */
+ bsd_compress, /* compress */
+ bsd_decompress, /* decompress */
+ bsd_incomp, /* incomp */
+ bsd_stats /* comp_stat */
+};
+
+/*************************************************************
+ * Module support routines
+ *************************************************************/
+
+int init_module(void)
+{
+ int answer = isdn_ppp_register_compressor (&ippp_bsd_compress);
+ if (answer == 0)
+ printk (KERN_INFO "PPP BSD Compression module registered\n");
+ return answer;
+}
+
+void cleanup_module(void)
+{
+ isdn_ppp_unregister_compressor (&ippp_bsd_compress);
+}
FUNET's LINUX-ADM group, linux-adm@nic.funet.fi
TCL-scripts by Sam Shen (who was at: slshen@lbl.gov)