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IABSD.fr/src/sys/net/bsd-comp.c
claudio
- sys/net/bsd-comp.c
-
/* $OpenBSD: bsd-comp.c,v 1.16 2018/11/09 14:14:31 claudio Exp $ */ /* $NetBSD: bsd-comp.c,v 1.6 1996/10/13 02:10:58 christos Exp $ */ /* Because this code is derived from the 4.3BSD compress source: * * * 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. 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. */ /* * This version is for use with mbufs on BSD-derived systems. */ #include <sys/param.h> #include <sys/systm.h> #include <sys/mbuf.h> #include <sys/socket.h> #include <net/if.h> #include <net/if_var.h> #include <net/ppp_defs.h> #include <net/if_ppp.h> #define PACKETPTR struct mbuf * #include <net/ppp-comp.h> #if DO_BSD_COMPRESS /* * PPP "BSD compress" compression * The differences between this compression and the classic BSD LZW * source are obvious from the requirement that the classic code worked * with files while this handles arbitrarily long streams that * are broken into packets. They are: * * When the code size expands, a block of junk is not emitted by * the compressor and not expected by the decompressor. * * New codes are not necessarily assigned every time an old * code is output by the compressor. This is because a packet * end forces a code to be emitted, but does not imply that a * new sequence has been seen. * * The compression ratio is checked at the first end of a packet * after the appropriate gap. Besides simplifying and speeding * things up, this makes it more likely that the transmitter * and receiver will agree when the dictionary is cleared when * compression is not going well. */ /* * A dictionary for doing BSD compress. */ struct bsd_db { int totlen; /* length of this structure */ u_int hsize; /* size of the hash table */ u_char hshift; /* used in hash function */ u_char n_bits; /* current bits/code */ u_char maxbits; u_char debug; u_char unit; u_int16_t seqno; /* sequence # of next packet */ u_int hdrlen; /* header length to preallocate */ u_int mru; u_int maxmaxcode; /* largest valid code */ u_int max_ent; /* largest code in use */ u_int in_count; /* uncompressed bytes, aged */ u_int bytes_out; /* compressed bytes, aged */ u_int ratio; /* recent compression ratio */ u_int checkpoint; /* when to next check the ratio */ u_int clear_count; /* times dictionary cleared */ u_int incomp_count; /* incompressible packets */ u_int incomp_bytes; /* incompressible bytes */ u_int uncomp_count; /* uncompressed packets */ u_int uncomp_bytes; /* uncompressed bytes */ u_int comp_count; /* compressed packets */ u_int comp_bytes; /* compressed bytes */ u_int16_t *lens; /* array of lengths of codes */ struct bsd_dict { union { /* hash value */ u_int32_t fcode; struct { #if BYTE_ORDER == LITTLE_ENDIAN u_int16_t prefix; /* preceding code */ u_char suffix; /* last character of new code */ u_char pad; #else u_char pad; u_char suffix; /* last character of new code */ u_int16_t prefix; /* preceding code */ #endif } hs; } f; u_int16_t codem1; /* output of hash table -1 */ u_int16_t cptr; /* map code to hash table entry */ } dict[1]; }; #define BSD_OVHD 2 /* BSD compress overhead/packet */ #define BSD_INIT_BITS BSD_MIN_BITS static void *bsd_comp_alloc(u_char *options, int opt_len); static void *bsd_decomp_alloc(u_char *options, int opt_len); static void bsd_free(void *state); static int bsd_comp_init(void *state, u_char *options, int opt_len, int unit, int hdrlen, int debug); static int bsd_decomp_init(void *state, u_char *options, int opt_len, int unit, int hdrlen, int mru, int debug); static int bsd_compress(void *state, struct mbuf **mret, struct mbuf *mp, int slen, int maxolen); static void bsd_incomp(void *state, struct mbuf *dmsg); static int bsd_decompress(void *state, struct mbuf *cmp, struct mbuf **dmpp); static void bsd_reset(void *state); static void bsd_comp_stats(void *state, struct compstat *stats); /* * Procedures exported to if_ppp.c. */ struct compressor ppp_bsd_compress = { CI_BSD_COMPRESS, /* compress_proto */ bsd_comp_alloc, /* comp_alloc */ bsd_free, /* comp_free */ bsd_comp_init, /* comp_init */ bsd_reset, /* comp_reset */ bsd_compress, /* compress */ bsd_comp_stats, /* comp_stat */ bsd_decomp_alloc, /* decomp_alloc */ bsd_free, /* decomp_free */ bsd_decomp_init, /* decomp_init */ bsd_reset, /* decomp_reset */ bsd_decompress, /* decompress */ bsd_incomp, /* incomp */ bsd_comp_stats, /* decomp_stat */ }; /* * 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(BSD_MAX_BITS) #define BSD_HASH(prefix,suffix,hshift) ((((u_int32_t)(suffix)) << (hshift)) \ ^ (u_int32_t)(prefix)) #define BSD_KEY(prefix,suffix) ((((u_int32_t)(suffix)) << 16) \ + (u_int32_t)(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) static void bsd_clear(struct bsd_db *); static int bsd_check(struct bsd_db *); static void *bsd_alloc(u_char *, int, int); static int bsd_init(struct bsd_db *, u_char *, int, int, int, int, int, int); /* * clear the dictionary */ static void bsd_clear(db) struct bsd_db *db; { db->clear_count++; db->max_ent = FIRST-1; db->n_bits = BSD_INIT_BITS; db->ratio = 0; db->bytes_out = 0; db->in_count = 0; db->incomp_count = 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 /* 1=output CLEAR */ bsd_check(db) struct bsd_db *db; { u_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/4; db->bytes_out -= db->bytes_out/4; } 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_comp_stats(state, stats) void *state; struct compstat *stats; { struct bsd_db *db = (struct bsd_db *) state; u_int out; 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->ratio = db->in_count; out = db->bytes_out; if (stats->ratio <= 0x7fffff) stats->ratio <<= 8; else out >>= 8; if (out != 0) stats->ratio /= out; } /* * Reset state, as on a CCP ResetReq. */ static void bsd_reset(state) void *state; { struct bsd_db *db = (struct bsd_db *) state; db->seqno = 0; bsd_clear(db); db->clear_count = 0; } /* * Allocate space for a (de) compressor. */ static void * bsd_alloc(options, opt_len, decomp) u_char *options; int opt_len, decomp; { int bits; u_int newlen, hsize, hshift, maxmaxcode; struct bsd_db *db; if (opt_len < CILEN_BSD_COMPRESS || options[0] != CI_BSD_COMPRESS || options[1] != CILEN_BSD_COMPRESS || BSD_VERSION(options[2]) != BSD_CURRENT_VERSION) return NULL; bits = BSD_NBITS(options[2]); switch (bits) { case 9: /* needs 82152 for both directions */ case 10: /* needs 84144 */ case 11: /* needs 88240 */ case 12: /* needs 96432 */ hsize = 5003; hshift = 4; break; case 13: /* needs 176784 */ hsize = 9001; hshift = 5; break; case 14: /* needs 353744 */ hsize = 18013; hshift = 6; break; case 15: /* needs 691440 */ hsize = 35023; hshift = 7; break; case 16: /* needs 1366160--far too much, */ /* hsize = 69001; */ /* and 69001 is too big for cptr */ /* hshift = 8; */ /* in struct bsd_db */ /* break; */ default: return NULL; } maxmaxcode = MAXCODE(bits); newlen = sizeof(*db) + (hsize-1) * (sizeof(db->dict[0])); db = malloc(newlen, M_DEVBUF, M_NOWAIT|M_ZERO); if (!db) return NULL; if (!decomp) { db->lens = NULL; } else { db->lens = mallocarray(maxmaxcode + 1, sizeof(db->lens[0]), M_DEVBUF, M_NOWAIT); if (!db->lens) { free(db, M_DEVBUF, newlen); return NULL; } } db->totlen = newlen; db->hsize = hsize; db->hshift = hshift; db->maxmaxcode = maxmaxcode; db->maxbits = bits; return (void *) db; } static void bsd_free(state) void *state; { struct bsd_db *db = (struct bsd_db *) state; if (db->lens) free(db->lens, M_DEVBUF, (db->maxmaxcode + 1) * sizeof(db->lens[0])); free(db, M_DEVBUF, db->totlen); } static void * bsd_comp_alloc(options, opt_len) u_char *options; int opt_len; { return bsd_alloc(options, opt_len, 0); } static void * bsd_decomp_alloc(options, opt_len) u_char *options; int opt_len; { return bsd_alloc(options, opt_len, 1); } /* * Initialize the database. */ static int bsd_init(db, options, opt_len, unit, hdrlen, mru, debug, decomp) struct bsd_db *db; u_char *options; int opt_len, unit, hdrlen, mru, debug, decomp; { int i; if (opt_len < CILEN_BSD_COMPRESS || options[0] != CI_BSD_COMPRESS || options[1] != CILEN_BSD_COMPRESS || BSD_VERSION(options[2]) != BSD_CURRENT_VERSION || BSD_NBITS(options[2]) != db->maxbits || (decomp && db->lens == NULL)) return 0; if (decomp) { i = LAST+1; while (i != 0) db->lens[--i] = 1; } i = db->hsize; while (i != 0) { db->dict[--i].codem1 = BADCODEM1; db->dict[i].cptr = 0; } db->unit = unit; db->hdrlen = hdrlen; db->mru = mru; #ifndef DEBUG if (debug) #endif db->debug = 1; bsd_reset(db); return 1; } static int bsd_comp_init(state, options, opt_len, unit, hdrlen, debug) void *state; u_char *options; int opt_len, unit, hdrlen, debug; { return bsd_init((struct bsd_db *) state, options, opt_len, unit, hdrlen, 0, debug, 0); } static int bsd_decomp_init(state, options, opt_len, unit, hdrlen, mru, debug) void *state; u_char *options; int opt_len, unit, hdrlen, mru, debug; { return bsd_init((struct bsd_db *) state, options, opt_len, unit, hdrlen, mru, debug, 1); } /* * compress a packet * One change from the BSD compress command is that when the * code size expands, we do not output a bunch of padding. */ int /* new slen */ bsd_compress(state, mret, mp, slen, maxolen) void *state; struct mbuf **mret; /* return compressed mbuf chain here */ struct mbuf *mp; /* from here */ int slen; /* uncompressed length */ int maxolen; /* max compressed length */ { struct bsd_db *db = (struct bsd_db *) state; int hshift = db->hshift; u_int max_ent = db->max_ent; u_int n_bits = db->n_bits; u_int bitno = 32; u_int32_t accm = 0, fcode; struct bsd_dict *dictp; u_char c; int hval, disp, ent, ilen; u_char *rptr, *wptr; u_char *cp_end; int olen; struct mbuf *m; #define PUTBYTE(v) { \ ++olen; \ if (wptr) { \ *wptr++ = (v); \ if (wptr >= cp_end) { \ m->m_len = wptr - mtod(m, u_char *); \ MGET(m->m_next, M_DONTWAIT, MT_DATA); \ m = m->m_next; \ if (m) { \ m->m_len = 0; \ if (maxolen - olen > MLEN) \ MCLGET(m, M_DONTWAIT); \ wptr = mtod(m, u_char *); \ cp_end = wptr + m_trailingspace(m); \ } else \ wptr = NULL; \ } \ } \ } #define OUTPUT(ent) { \ bitno -= n_bits; \ accm |= ((ent) << bitno); \ do { \ PUTBYTE(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. */ rptr = mtod(mp, u_char *); ent = PPP_PROTOCOL(rptr); if (ent < 0x21 || ent > 0xf9) { *mret = NULL; return slen; } /* Don't generate compressed packets which are larger than the uncompressed packet. */ if (maxolen > slen) maxolen = slen; /* Allocate one mbuf to start with. */ MGET(m, M_DONTWAIT, MT_DATA); *mret = m; if (m != NULL) { m->m_len = 0; if (maxolen + db->hdrlen > MLEN) MCLGET(m, M_DONTWAIT); m->m_data += db->hdrlen; wptr = mtod(m, u_char *); cp_end = wptr + m_trailingspace(m); } else wptr = cp_end = NULL; /* * Copy the PPP header over, changing the protocol, * and install the 2-byte packet sequence number. */ if (wptr) { *wptr++ = PPP_ADDRESS(rptr); /* assumes the ppp header is */ *wptr++ = PPP_CONTROL(rptr); /* all in one mbuf */ *wptr++ = 0; /* change the protocol */ *wptr++ = PPP_COMP; *wptr++ = db->seqno >> 8; *wptr++ = db->seqno; } ++db->seqno; olen = 0; rptr += PPP_HDRLEN; slen = mp->m_len - PPP_HDRLEN; ilen = slen + 1; for (;;) { if (slen <= 0) { mp = mp->m_next; if (!mp) break; rptr = mtod(mp, u_char *); slen = mp->m_len; if (!slen) continue; /* handle 0-length buffers */ ilen += slen; } slen--; c = *rptr++; fcode = BSD_KEY(ent, c); hval = BSD_HASH(ent, c, hshift); dictp = &db->dict[hval]; /* Validate and then check the entry. */ if (dictp->codem1 >= max_ent) goto nomatch; if (dictp->f.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 = &db->dict[hval]; if (dictp->codem1 >= max_ent) goto nomatch; } while (dictp->f.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; /* expand code size if needed */ if (max_ent >= MAXCODE(n_bits)) db->n_bits = ++n_bits; /* Invalidate old hash table entry using * this code, and then take it over. */ dictp2 = &db->dict[max_ent+1]; if (db->dict[dictp2->cptr].codem1 == max_ent) db->dict[dictp2->cptr].codem1 = BADCODEM1; dictp2->cptr = hval; dictp->codem1 = max_ent; dictp->f.fcode = fcode; db->max_ent = ++max_ent; } ent = c; } OUTPUT(ent); /* output the last code */ db->bytes_out += olen; db->in_count += ilen; if (bitno < 32) ++db->bytes_out; /* count complete bytes */ if (bsd_check(db)) OUTPUT(CLEAR); /* do not count the CLEAR */ /* * Pad dribble bits of last code with ones. * Do not emit a completely useless byte of ones. */ if (bitno != 32) PUTBYTE((accm | (0xff << (bitno-8))) >> 24); if (m != NULL) { m->m_len = wptr - mtod(m, u_char *); m->m_next = NULL; } /* * Increase code size if we would have without the packet * boundary and as the decompressor will. */ if (max_ent >= MAXCODE(n_bits) && max_ent < db->maxmaxcode) db->n_bits++; db->uncomp_bytes += ilen; ++db->uncomp_count; if (olen + PPP_HDRLEN + BSD_OVHD > maxolen) { /* throw away the compressed stuff if it is longer than uncompressed */ m_freemp(mret); ++db->incomp_count; db->incomp_bytes += ilen; } else { ++db->comp_count; db->comp_bytes += olen + BSD_OVHD; } return olen + PPP_HDRLEN + BSD_OVHD; #undef OUTPUT #undef PUTBYTE } /* * Update the "BSD Compress" dictionary on the receiver for * incompressible data by pretending to compress the incoming data. */ static void bsd_incomp(state, dmsg) void *state; struct mbuf *dmsg; { struct bsd_db *db = (struct bsd_db *) state; u_int hshift = db->hshift; u_int max_ent = db->max_ent; u_int n_bits = db->n_bits; struct bsd_dict *dictp; u_int32_t fcode; u_char c; u_int32_t hval, disp; int slen, ilen; u_int bitno = 7; u_char *rptr; u_int ent; /* * If the protocol is not in the range we're interested in, * just return without looking at the packet. If it is, * the protocol becomes the first byte to "compress". */ rptr = mtod(dmsg, u_char *); ent = PPP_PROTOCOL(rptr); if (ent < 0x21 || ent > 0xf9) return; db->incomp_count++; db->seqno++; ilen = 1; /* count the protocol as 1 byte */ rptr += PPP_HDRLEN; slen = dmsg->m_len - PPP_HDRLEN; for (;;) { if (slen <= 0) { dmsg = dmsg->m_next; if (!dmsg) break; rptr = mtod(dmsg, u_char *); slen = dmsg->m_len; continue; } ilen += slen; do { c = *rptr++; fcode = BSD_KEY(ent, c); hval = BSD_HASH(ent, c, hshift); dictp = &db->dict[hval]; /* validate and then check the entry */ if (dictp->codem1 >= max_ent) goto nomatch; if (dictp->f.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 = &db->dict[hval]; if (dictp->codem1 >= max_ent) goto nomatch; } while (dictp->f.fcode != fcode); ent = dictp->codem1+1; continue; /* finally found (prefix,suffix) */ nomatch: /* output (count) the prefix */ bitno += n_bits; /* code -> hashtable */ if (max_ent < db->maxmaxcode) { struct bsd_dict *dictp2; /* expand code size if needed */ if (max_ent >= MAXCODE(n_bits)) db->n_bits = ++n_bits; /* Invalidate previous hash table entry * assigned this code, and then take it over. */ dictp2 = &db->dict[max_ent+1]; if (db->dict[dictp2->cptr].codem1 == max_ent) db->dict[dictp2->cptr].codem1 = BADCODEM1; dictp2->cptr = hval; dictp->codem1 = max_ent; dictp->f.fcode = fcode; db->max_ent = ++max_ent; db->lens[max_ent] = db->lens[ent]+1; } ent = c; } while (--slen != 0); } bitno += n_bits; /* output (count) the last code */ db->bytes_out += bitno/8; db->in_count += ilen; (void)bsd_check(db); ++db->incomp_count; db->incomp_bytes += ilen; ++db->uncomp_count; db->uncomp_bytes += ilen; /* Increase code size if we would have without the packet * boundary and as the decompressor will. */ if (max_ent >= MAXCODE(n_bits) && max_ent < db->maxmaxcode) db->n_bits++; } /* * Decompress "BSD Compress". * * 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 bsd_decompress(state, cmp, dmpp) void *state; struct mbuf *cmp, **dmpp; { struct bsd_db *db = (struct bsd_db *) state; u_int max_ent = db->max_ent; u_int32_t accm = 0; u_int bitno = 32; /* 1st valid bit in accm */ u_int n_bits = db->n_bits; u_int tgtbitno = 32-n_bits; /* bitno when we have a code */ struct bsd_dict *dictp; int explen, i, seq, len; u_int incode, oldcode, finchar; u_char *p, *rptr, *wptr; struct mbuf *m, *dmp, *mret; int adrs, ctrl, ilen; int space, codelen, extra; /* * Save the address/control from the PPP header * and then get the sequence number. */ *dmpp = NULL; rptr = mtod(cmp, u_char *); adrs = PPP_ADDRESS(rptr); ctrl = PPP_CONTROL(rptr); rptr += PPP_HDRLEN; len = cmp->m_len - PPP_HDRLEN; seq = 0; for (i = 0; i < 2; ++i) { while (len <= 0) { cmp = cmp->m_next; if (cmp == NULL) return DECOMP_ERROR; rptr = mtod(cmp, u_char *); len = cmp->m_len; } seq = (seq << 8) + *rptr++; --len; } /* * Check the sequence number and give up if it differs from * the value we're expecting. */ if (seq != db->seqno) { if (db->debug) printf("bsd_decomp%d: bad sequence # %d, expected %d\n", db->unit, seq, db->seqno - 1); return DECOMP_ERROR; } ++db->seqno; /* * Allocate one mbuf to start with. */ MGETHDR(dmp, M_DONTWAIT, MT_DATA); if (dmp == NULL) return DECOMP_ERROR; mret = dmp; dmp->m_len = 0; dmp->m_next = NULL; MCLGET(dmp, M_DONTWAIT); dmp->m_data += db->hdrlen; wptr = mtod(dmp, u_char *); space = m_trailingspace(dmp) - PPP_HDRLEN + 1; /* * Fill in the ppp header, but not the last byte of the protocol * (that comes from the decompressed data). */ wptr[0] = adrs; wptr[1] = ctrl; wptr[2] = 0; wptr += PPP_HDRLEN - 1; ilen = len; oldcode = CLEAR; explen = 0; for (;;) { if (len == 0) { cmp = cmp->m_next; if (!cmp) /* quit at end of message */ break; rptr = mtod(cmp, u_char *); len = cmp->m_len; ilen += len; continue; /* handle 0-length buffers */ } /* * 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 |= *rptr++ << bitno; --len; if (tgtbitno < bitno) continue; incode = accm >> tgtbitno; accm <<= n_bits; bitno += n_bits; if (incode == CLEAR) { /* * The dictionary must only be cleared at * the end of a packet. But there could be an * empty mbuf at the end. */ if (len > 0 || cmp->m_next != NULL) { while ((cmp = cmp->m_next) != NULL) len += cmp->m_len; if (len > 0) { m_freem(mret); if (db->debug) printf("bsd_decomp%d: bad CLEAR\n", db->unit); return DECOMP_FATALERROR; /* probably a bug */ } } bsd_clear(db); explen = ilen = 0; break; } if (incode > max_ent + 2 || incode > db->maxmaxcode || (incode > max_ent && oldcode == CLEAR)) { m_freem(mret); if (db->debug) { printf("bsd_decomp%d: bad code 0x%x oldcode=0x%x ", db->unit, incode, oldcode); printf("max_ent=0x%x explen=%d seqno=%d\n", max_ent, explen, 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 = db->lens[finchar]; explen += codelen + extra; if (explen > db->mru + 1) { m_freem(mret); if (db->debug) { printf("bsd_decomp%d: ran out of mru\n", db->unit); #ifdef DEBUG while ((cmp = cmp->m_next) != NULL) len += cmp->m_len; printf(" len=%d, finchar=0x%x, codelen=%d, explen=%d\n", len, finchar, codelen, explen); #endif } return DECOMP_FATALERROR; } /* * For simplicity, the decoded characters go in a single mbuf, * so we allocate a single extra cluster mbuf if necessary. */ if ((space -= codelen + extra) < 0) { dmp->m_len = wptr - mtod(dmp, u_char *); MGET(m, M_DONTWAIT, MT_DATA); if (m == NULL) { m_freem(mret); return DECOMP_ERROR; } m->m_len = 0; m->m_next = NULL; dmp->m_next = m; MCLGET(m, M_DONTWAIT); space = m_trailingspace(m) - (codelen + extra); if (space < 0) { /* now that's what I call *compression*. */ m_freem(mret); return DECOMP_ERROR; } dmp = m; wptr = mtod(dmp, u_char *); } /* * Decode this code and install it in the decompressed buffer. */ p = (wptr += codelen); while (finchar > LAST) { dictp = &db->dict[db->dict[finchar].cptr]; #ifdef DEBUG if (--codelen <= 0 || dictp->codem1 != finchar-1) goto bad; #endif *--p = dictp->f.hs.suffix; finchar = dictp->f.hs.prefix; } *--p = finchar; #ifdef DEBUG if (--codelen != 0) printf("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 */ *wptr++ = 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; u_int32_t fcode; u_int32_t hval, disp; fcode = BSD_KEY(oldcode,finchar); hval = BSD_HASH(oldcode,finchar,db->hshift); dictp = &db->dict[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 = &db->dict[hval]; } while (dictp->codem1 < max_ent); } /* * Invalidate previous hash table entry * assigned this code, and then take it over */ dictp2 = &db->dict[max_ent+1]; if (db->dict[dictp2->cptr].codem1 == max_ent) { db->dict[dictp2->cptr].codem1 = BADCODEM1; } dictp2->cptr = hval; dictp->codem1 = max_ent; dictp->f.fcode = fcode; db->max_ent = ++max_ent; db->lens[max_ent] = db->lens[oldcode]+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; } dmp->m_len = wptr - mtod(dmp, u_char *); /* * Keep the checkpoint right so that incompressible packets * clear the dictionary at the right times. */ db->bytes_out += ilen; db->in_count += explen; if (bsd_check(db) && db->debug) { printf("bsd_decomp%d: peer should have cleared dictionary\n", db->unit); } ++db->comp_count; db->comp_bytes += ilen + BSD_OVHD; ++db->uncomp_count; db->uncomp_bytes += explen; *dmpp = mret; return DECOMP_OK; #ifdef DEBUG bad: if (codelen <= 0) { printf("bsd_decomp%d: fell off end of chain ", db->unit); printf("0x%x at 0x%x by 0x%x, max_ent=0x%x\n", incode, finchar, db->dict[finchar].cptr, max_ent); } else if (dictp->codem1 != finchar-1) { printf("bsd_decomp%d: bad code chain 0x%x finchar=0x%x ", db->unit, incode, finchar); printf("oldcode=0x%x cptr=0x%x codem1=0x%x\n", oldcode, db->dict[finchar].cptr, dictp->codem1); } m_freem(mret); return DECOMP_FATALERROR; #endif /* DEBUG */ } #endif /* DO_BSD_COMPRESS */