text: /*
   *  ==FILEVERSION 980319==
   *
   * ppp_deflate.c - interface the zlib procedures for Deflate compression
   * and decompression (as used by gzip) to the PPP code.
   * This version is for use with Linux kernel 1.3.X and later.
   *
   * Copyright (c) 1994 The Australian National University.
   * All rights reserved.
   *
   * Permission to use, copy, modify, and distribute this software and its
   * documentation is hereby granted, provided that the above copyright
   * notice appears in all copies.  This software is provided without any
   * warranty, express or implied. The Australian National University
   * makes no representations about the suitability of this software for
   * any purpose.
   *
   * IN NO EVENT SHALL THE AUSTRALIAN NATIONAL UNIVERSITY BE LIABLE TO ANY
   * PARTY FOR DIRECT, INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES
   * ARISING OUT OF THE USE OF THIS SOFTWARE AND ITS DOCUMENTATION, EVEN IF
   * THE AUSTRALIAN NATIONAL UNIVERSITY HAS BEEN ADVISED OF THE POSSIBILITY
   * OF SUCH DAMAGE.
   *
   * THE AUSTRALIAN NATIONAL UNIVERSITY SPECIFICALLY DISCLAIMS ANY WARRANTIES,
   * INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY
   * AND FITNESS FOR A PARTICULAR PURPOSE.  THE SOFTWARE PROVIDED HEREUNDER IS
   * ON AN "AS IS" BASIS, AND THE AUSTRALIAN NATIONAL UNIVERSITY HAS NO
   * OBLIGATION TO PROVIDE MAINTENANCE, SUPPORT, UPDATES, ENHANCEMENTS,
   * OR MODIFICATIONS.
   *
   * From: deflate.c,v 1.1 1996/01/18 03:17:48 paulus Exp
   */
  
  #include <linux/module.h>
  #include <linux/version.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>
  
  #undef VERSION
  /* a nice define to generate linux version numbers */
  #define VERSION(major,minor,patch) (((((major)<<8)+(minor))<<8)+(patch))
  
  #if LINUX_VERSION_CODE >= VERSION(2,1,4)
  #include <linux/vmalloc.h>
  #endif
  
  #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 <linux/netdevice.h>
  #include <linux/skbuff.h>
  #include <linux/inet.h>
  #include <linux/ioctl.h>
  
  #include <linux/ppp_defs.h>
  #include <linux/ppp-comp.h>
  
  #include "zlib.c"
  
  /*
   * State for a Deflate (de)compressor.
   */
  struct ppp_deflate_state {
      int		seqno;
      int		w_size;
      int		unit;
      int		mru;
      int		debug;
      z_stream	strm;
      struct compstat stats;
  };
  
  #define DEFLATE_OVHD	2		/* Deflate overhead/packet */
  
  static void	*zalloc __P((void *, unsigned int items, unsigned int size));
  static void	*zalloc_init __P((void *, unsigned int items,
  				  unsigned int size));
  static void	zfree __P((void *, void *ptr));
  static void	*z_comp_alloc __P((unsigned char *options, int opt_len));
  static void	*z_decomp_alloc __P((unsigned char *options, int opt_len));
  static void	z_comp_free __P((void *state));
  static void	z_decomp_free __P((void *state));
  static int	z_comp_init __P((void *state, unsigned char *options,
  				 int opt_len,
  				 int unit, int hdrlen, int debug));
  static int	z_decomp_init __P((void *state, unsigned char *options,
  				   int opt_len,
  				   int unit, int hdrlen, int mru, int debug));
  static int	z_compress __P((void *state, unsigned char *rptr,
  				unsigned char *obuf,
  				int isize, int osize));
  static void	z_incomp __P((void *state, unsigned char *ibuf, int icnt));
  static int	z_decompress __P((void *state, unsigned char *ibuf,
  				int isize, unsigned char *obuf, int osize));
  static void	z_comp_reset __P((void *state));
  static void	z_decomp_reset __P((void *state));
  static void	z_comp_stats __P((void *state, struct compstat *stats));
  
  struct chunk_header {
  	int valloced;		/* allocated with valloc, not kmalloc */
  	int guard;		/* check for overwritten header */
  };
  
  #define GUARD_MAGIC	0x77a8011a
  #define MIN_VMALLOC	2048	/* use kmalloc for blocks < this */
  
  /*
   * Space allocation and freeing routines for use by zlib routines.
   */
  void
  zfree(arg, ptr)
      void *arg;
      void *ptr;
  {
  	struct chunk_header *hdr = ((struct chunk_header *)ptr) - 1;
  
  	if (hdr->guard != GUARD_MAGIC) {
  		printk(KERN_WARNING "zfree: header corrupted (%x %x) at %p\n",
  		       hdr->valloced, hdr->guard, hdr);
  		return;
  	}
  	if (hdr->valloced)
  		vfree(hdr);
  	else
  		kfree(hdr);
  }
  
  void *
  zalloc(arg, items, size)
      void *arg;
      unsigned int items, size;
  {
  	struct chunk_header *hdr;
  	unsigned nbytes;
  
  	nbytes = items * size + sizeof(*hdr);
  	hdr = kmalloc(nbytes, GFP_ATOMIC);
  	if (hdr == 0)
  		return 0;
  	hdr->valloced = 0;
  	hdr->guard = GUARD_MAGIC;
  	return (void *) (hdr + 1);
  }
  
  void *
  zalloc_init(arg, items, size)
      void *arg;
      unsigned int items, size;
  {
  	struct chunk_header *hdr;
  	unsigned nbytes;
  
  	nbytes = items * size + sizeof(*hdr);
  	if (nbytes >= MIN_VMALLOC)
  		hdr = vmalloc(nbytes);
  	else
  		hdr = kmalloc(nbytes, GFP_KERNEL);
  	if (hdr == 0)
  		return 0;
  	hdr->valloced = nbytes >= MIN_VMALLOC;
  	hdr->guard = GUARD_MAGIC;
  	return (void *) (hdr + 1);
  }
  
  static void
  z_comp_free(arg)
      void *arg;
  {
  	struct ppp_deflate_state *state = (struct ppp_deflate_state *) arg;
  
  	if (state) {
  		deflateEnd(&state->strm);
  		kfree(state);
  		MOD_DEC_USE_COUNT;
  	}
  }
  
  /*
   * Allocate space for a compressor.
   */
  static void *
  z_comp_alloc(options, opt_len)
      unsigned char *options;
      int opt_len;
  {
  	struct ppp_deflate_state *state;
  	int w_size;
  
  	if (opt_len != CILEN_DEFLATE
  	    || (options[0] != CI_DEFLATE && options[0] != CI_DEFLATE_DRAFT)
  	    || options[1] != CILEN_DEFLATE
  	    || DEFLATE_METHOD(options[2]) != DEFLATE_METHOD_VAL
  	    || options[3] != DEFLATE_CHK_SEQUENCE)
  		return NULL;
  	w_size = DEFLATE_SIZE(options[2]);
  	if (w_size < DEFLATE_MIN_SIZE || w_size > DEFLATE_MAX_SIZE)
  		return NULL;
  
  	state = (struct ppp_deflate_state *) kmalloc(sizeof(*state), GFP_KERNEL);
  	if (state == NULL)
  		return NULL;
  
  	MOD_INC_USE_COUNT;
  	memset (state, 0, sizeof (struct ppp_deflate_state));
  	state->strm.next_in = NULL;
  	state->strm.zalloc  = zalloc_init;
  	state->strm.zfree   = zfree;
  	state->w_size       = w_size;
  
  	if (deflateInit2(&state->strm, Z_DEFAULT_COMPRESSION,
  			 DEFLATE_METHOD_VAL, -w_size, 8, Z_DEFAULT_STRATEGY)
  	    != Z_OK)
  		goto out_free;
  	state->strm.zalloc = zalloc;
  	return (void *) state;
  
  out_free:
  	z_comp_free(state);
  	MOD_DEC_USE_COUNT;
  	return NULL;
  }
  
  static int
  z_comp_init(arg, options, opt_len, unit, hdrlen, debug)
      void *arg;
      unsigned char *options;
      int opt_len, unit, hdrlen, debug;
  {
  	struct ppp_deflate_state *state = (struct ppp_deflate_state *) arg;
  
  	if (opt_len < CILEN_DEFLATE
  	    || (options[0] != CI_DEFLATE && options[0] != CI_DEFLATE_DRAFT)
  	    || options[1] != CILEN_DEFLATE
  	    || DEFLATE_METHOD(options[2]) != DEFLATE_METHOD_VAL
  	    || DEFLATE_SIZE(options[2]) != state->w_size
  	    || options[3] != DEFLATE_CHK_SEQUENCE)
  		return 0;
  
  	state->seqno = 0;
  	state->unit  = unit;
  	state->debug = debug;
  
  	deflateReset(&state->strm);
  
  	return 1;
  }
  
  static void
  z_comp_reset(arg)
      void *arg;
  {
  	struct ppp_deflate_state *state = (struct ppp_deflate_state *) arg;
  
  	state->seqno = 0;
  	deflateReset(&state->strm);
  }
  
  int
  z_compress(arg, rptr, obuf, isize, osize)
      void *arg;
      unsigned char *rptr;	/* uncompressed packet (in) */
      unsigned char *obuf;	/* compressed packet (out) */
      int isize, osize;
  {
  	struct ppp_deflate_state *state = (struct ppp_deflate_state *) arg;
  	int r, proto, off, olen, oavail;
  	unsigned char *wptr;
  
  	/*
  	 * Check that the protocol is in the range we handle.
  	 */
  	proto = PPP_PROTOCOL(rptr);
  	if (proto > 0x3fff || proto == 0xfd || proto == 0xfb)
  		return 0;
  
  	/* Don't generate compressed packets which are larger than
  	   the uncompressed packet. */
  	if (osize > isize)
  		osize = isize;
  
  	wptr = obuf;
  
  	/*
  	 * Copy over the PPP header and store the 2-byte sequence number.
  	 */
  	wptr[0] = PPP_ADDRESS(rptr);
  	wptr[1] = PPP_CONTROL(rptr);
  	wptr[2] = PPP_COMP >> 8;
  	wptr[3] = PPP_COMP;
  	wptr += PPP_HDRLEN;
  	wptr[0] = state->seqno >> 8;
  	wptr[1] = state->seqno;
  	wptr += DEFLATE_OVHD;
  	olen = PPP_HDRLEN + DEFLATE_OVHD;
  	state->strm.next_out = wptr;
  	state->strm.avail_out = oavail = osize - olen;
  	++state->seqno;
  
  	off = (proto > 0xff) ? 2 : 3;	/* skip 1st proto byte if 0 */
  	rptr += off;
  	state->strm.next_in = rptr;
  	state->strm.avail_in = (isize - off);
  
  	for (;;) {
  		r = deflate(&state->strm, Z_PACKET_FLUSH);
  		if (r != Z_OK) {
  			if (state->debug)
  				printk(KERN_ERR
  				       "z_compress: deflate returned %d\n", r);
  			break;
  		}
  		if (state->strm.avail_out == 0) {
  			olen += oavail;
  			state->strm.next_out = NULL;
  			state->strm.avail_out = oavail = 1000000;
  		} else {
  			break;		/* all done */
  		}
  	}
  	olen += oavail - state->strm.avail_out;
  
  	/*
  	 * See if we managed to reduce the size of the packet.
  	 */
  	if (olen < isize) {
  		state->stats.comp_bytes += olen;
  		state->stats.comp_packets++;
  	} else {
  		state->stats.inc_bytes += isize;
  		state->stats.inc_packets++;
  		olen = 0;
  	}
  	state->stats.unc_bytes += isize;
  	state->stats.unc_packets++;
  
  	return olen;
  }
  
  static void
  z_comp_stats(arg, stats)
      void *arg;
      struct compstat *stats;
  {
  	struct ppp_deflate_state *state = (struct ppp_deflate_state *) arg;
  
  	*stats = state->stats;
  }
  
  static void
  z_decomp_free(arg)
      void *arg;
  {
  	struct ppp_deflate_state *state = (struct ppp_deflate_state *) arg;
  
  	if (state) {
  		inflateEnd(&state->strm);
  		kfree(state);
  		MOD_DEC_USE_COUNT;
  	}
  }
  
  /*
   * Allocate space for a decompressor.
   */
  static void *
  z_decomp_alloc(options, opt_len)
      unsigned char *options;
      int opt_len;
  {
  	struct ppp_deflate_state *state;
  	int w_size;
  
  	if (opt_len != CILEN_DEFLATE
  	    || (options[0] != CI_DEFLATE && options[0] != CI_DEFLATE_DRAFT)
  	    || options[1] != CILEN_DEFLATE
  	    || DEFLATE_METHOD(options[2]) != DEFLATE_METHOD_VAL
  	    || options[3] != DEFLATE_CHK_SEQUENCE)
  		return NULL;
  	w_size = DEFLATE_SIZE(options[2]);
  	if (w_size < DEFLATE_MIN_SIZE || w_size > DEFLATE_MAX_SIZE)
  		return NULL;
  
  	state = (struct ppp_deflate_state *) kmalloc(sizeof(*state), GFP_KERNEL);
  	if (state == NULL)
  		return NULL;
  
  	MOD_INC_USE_COUNT;
  	memset (state, 0, sizeof (struct ppp_deflate_state));
  	state->w_size        = w_size;
  	state->strm.next_out = NULL;
  	state->strm.zalloc   = zalloc_init;
  	state->strm.zfree    = zfree;
  
  	if (inflateInit2(&state->strm, -w_size) != Z_OK)
  		goto out_free;
  	state->strm.zalloc = zalloc;
  	return (void *) state;
  
  out_free:
  	z_decomp_free(state);
  	MOD_DEC_USE_COUNT;
  	return NULL;
  }
  
  static int
  z_decomp_init(arg, options, opt_len, unit, hdrlen, mru, debug)
      void *arg;
      unsigned char *options;
      int opt_len, unit, hdrlen, mru, debug;
  {
  	struct ppp_deflate_state *state = (struct ppp_deflate_state *) arg;
  
  	if (opt_len < CILEN_DEFLATE
  	    || (options[0] != CI_DEFLATE && options[0] != CI_DEFLATE_DRAFT)
  	    || options[1] != CILEN_DEFLATE
  	    || DEFLATE_METHOD(options[2]) != DEFLATE_METHOD_VAL
  	    || DEFLATE_SIZE(options[2]) != state->w_size
  	    || options[3] != DEFLATE_CHK_SEQUENCE)
  		return 0;
  
  	state->seqno = 0;
  	state->unit  = unit;
  	state->debug = debug;
  	state->mru   = mru;
  
  	inflateReset(&state->strm);
  
  	return 1;
  }
  
  static void
  z_decomp_reset(arg)
      void *arg;
  {
  	struct ppp_deflate_state *state = (struct ppp_deflate_state *) arg;
  
  	state->seqno = 0;
  	inflateReset(&state->strm);
  }
  
  /*
   * Decompress a Deflate-compressed packet.
   *
   * Because of patent problems, we return DECOMP_ERROR for errors
   * found by inspecting the input data and for system problems, but
   * DECOMP_FATALERROR for any errors which could possibly be said to
   * be being detected "after" decompression.  For DECOMP_ERROR,
   * we can issue a CCP reset-request; for DECOMP_FATALERROR, we may be
   * infringing a patent of Motorola's if we do, so we take CCP down
   * instead.
   *
   * Given that the frame has the correct sequence number and a good FCS,
   * errors such as invalid codes in the input most likely indicate a
   * bug, so we return DECOMP_FATALERROR for them in order to turn off
   * compression, even though they are detected by inspecting the input.
   */
  int
  z_decompress(arg, ibuf, isize, obuf, osize)
      void *arg;
      unsigned char *ibuf;
      int isize;
      unsigned char *obuf;
      int osize;
  {
  	struct ppp_deflate_state *state = (struct ppp_deflate_state *) arg;
  	int olen, seq, r;
  	int decode_proto, overflow;
  	unsigned char overflow_buf[1];
  
  	if (isize <= PPP_HDRLEN + DEFLATE_OVHD) {
  		if (state->debug)
  			printk(KERN_DEBUG "z_decompress%d: short pkt (%d)\n",
  			       state->unit, isize);
  		return DECOMP_ERROR;
  	}
  
  	/* Check the sequence number. */
  	seq = (ibuf[PPP_HDRLEN] << 8) + ibuf[PPP_HDRLEN+1];
  	if (seq != state->seqno) {
  		if (state->debug)
  			printk(KERN_DEBUG "z_decompress%d: bad seq # %d, expected %d\n",
  			       state->unit, seq, state->seqno);
  		return DECOMP_ERROR;
  	}
  	++state->seqno;
  
  	/*
  	 * Fill in the first part of the PPP header.  The protocol field
  	 * comes from the decompressed data.
  	 */
  	obuf[0] = PPP_ADDRESS(ibuf);
  	obuf[1] = PPP_CONTROL(ibuf);
  	obuf[2] = 0;
  
  	/*
  	 * Set up to call inflate.  We set avail_out to 1 initially so we can
  	 * look at the first byte of the output and decide whether we have
  	 * a 1-byte or 2-byte protocol field.
  	 */
  	state->strm.next_in = ibuf + PPP_HDRLEN + DEFLATE_OVHD;
  	state->strm.avail_in = isize - (PPP_HDRLEN + DEFLATE_OVHD);
  	state->strm.next_out = obuf + 3;
  	state->strm.avail_out = 1;
  	decode_proto = 1;
  	overflow = 0;
  
  	/*
  	 * Call inflate, supplying more input or output as needed.
  	 */
  	for (;;) {
  		r = inflate(&state->strm, Z_PACKET_FLUSH);
  		if (r != Z_OK) {
  			if (state->debug)
  				printk(KERN_DEBUG "z_decompress%d: inflate returned %d (%s)\n",
  				       state->unit, r, (state->strm.msg? state->strm.msg: ""));
  			return DECOMP_FATALERROR;
  		}
  		if (state->strm.avail_out != 0)
  			break;		/* all done */
  		if (decode_proto) {
  			state->strm.avail_out = osize - PPP_HDRLEN;
  			if ((obuf[3] & 1) == 0) {
  				/* 2-byte protocol field */
  				obuf[2] = obuf[3];
  				--state->strm.next_out;
  				++state->strm.avail_out;
  			}
  			decode_proto = 0;
  		} else if (!overflow) {
  			/*
  			 * We've filled up the output buffer; the only way to
  			 * find out whether inflate has any more characters
  			 * left is to give it another byte of output space.
  			 */
  			state->strm.next_out = overflow_buf;
  			state->strm.avail_out = 1;
  			overflow = 1;
  		} else {
  			if (state->debug)
  				printk(KERN_DEBUG "z_decompress%d: ran out of mru\n",
  				       state->unit);
  			return DECOMP_FATALERROR;
  		}
  	}
  
  	if (decode_proto) {
  		if (state->debug)
  			printk(KERN_DEBUG "z_decompress%d: didn't get proto\n",
  			       state->unit);
  		return DECOMP_ERROR;
  	}
  
  	olen = osize + overflow - state->strm.avail_out;
  	state->stats.unc_bytes += olen;
  	state->stats.unc_packets++;
  	state->stats.comp_bytes += isize;
  	state->stats.comp_packets++;
  
  	return olen;
  }
  
  /*
   * Incompressible data has arrived - add it to the history.
   */
  static void
  z_incomp(arg, ibuf, icnt)
      void *arg;
      unsigned char *ibuf;
      int icnt;
  {
  	struct ppp_deflate_state *state = (struct ppp_deflate_state *) arg;
  	int proto, r;
  
  	/*
  	 * Check that the protocol is one we handle.
  	 */
  	proto = PPP_PROTOCOL(ibuf);
  	if (proto > 0x3fff || proto == 0xfd || proto == 0xfb)
  		return;
  
  	++state->seqno;
  
  	/*
  	 * We start at the either the 1st or 2nd byte of the protocol field,
  	 * depending on whether the protocol value is compressible.
  	 */
  	state->strm.next_in = ibuf + 3;
  	state->strm.avail_in = icnt - 3;
  	if (proto > 0xff) {
  		--state->strm.next_in;
  		++state->strm.avail_in;
  	}
  
  	r = inflateIncomp(&state->strm);
  	if (r != Z_OK) {
  		/* gak! */
  		if (state->debug) {
  			printk(KERN_DEBUG "z_incomp%d: inflateIncomp returned %d (%s)\n",
  			       state->unit, r, (state->strm.msg? state->strm.msg: ""));
  		}
  		return;
  	}
  
  	/*
  	 * Update stats.
  	 */
  	state->stats.inc_bytes += icnt;
  	state->stats.inc_packets++;
  	state->stats.unc_bytes += icnt;
  	state->stats.unc_packets++;
  }
  
  /*************************************************************
   * Module interface table
   *************************************************************/
  
  /* These are in ppp.c */
  extern int  ppp_register_compressor   (struct compressor *cp);
  extern void ppp_unregister_compressor (struct compressor *cp);
  
  /*
   * Procedures exported to if_ppp.c.
   */
  struct compressor ppp_deflate = {
  	CI_DEFLATE,		/* compress_proto */
  	z_comp_alloc,		/* comp_alloc */
  	z_comp_free,		/* comp_free */
  	z_comp_init,		/* comp_init */
  	z_comp_reset,		/* comp_reset */
  	z_compress,		/* compress */
  	z_comp_stats,		/* comp_stat */
  	z_decomp_alloc,		/* decomp_alloc */
  	z_decomp_free,		/* decomp_free */
  	z_decomp_init,		/* decomp_init */
  	z_decomp_reset,		/* decomp_reset */
  	z_decompress,		/* decompress */
  	z_incomp,		/* incomp */
  	z_comp_stats,		/* decomp_stat */
  };
  
  struct compressor ppp_deflate_draft = {
  	CI_DEFLATE_DRAFT,	/* compress_proto */
  	z_comp_alloc,		/* comp_alloc */
  	z_comp_free,		/* comp_free */
  	z_comp_init,		/* comp_init */
  	z_comp_reset,		/* comp_reset */
  	z_compress,		/* compress */
  	z_comp_stats,		/* comp_stat */
  	z_decomp_alloc,		/* decomp_alloc */
  	z_decomp_free,		/* decomp_free */
  	z_decomp_init,		/* decomp_init */
  	z_decomp_reset,		/* decomp_reset */
  	z_decompress,		/* decompress */
  	z_incomp,		/* incomp */
  	z_comp_stats,		/* decomp_stat */
  };
  
  #ifdef MODULE
  /*************************************************************
   * Module support routines
   *************************************************************/
  
  int
  init_module(void)
  {  
          int answer = ppp_register_compressor (&ppp_deflate);
          if (answer == 0)
                  printk (KERN_INFO
  			"PPP Deflate Compression module registered\n");
  	ppp_register_compressor(&ppp_deflate_draft);
          return answer;
  }
       
  void
  cleanup_module(void)
  {
  	if (MOD_IN_USE)
  		printk (KERN_INFO
  			"Deflate Compression module busy, remove delayed\n");
  	else {
  	        ppp_unregister_compressor (&ppp_deflate);
  	        ppp_unregister_compressor (&ppp_deflate_draft);
  	}
  }
  #endif
  