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+/*-
+ * 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.
+ *
+ * $FreeBSD: src/usr.sbin/ppp/pred.c,v 1.35.26.1 2010/12/21 17:10:29 kensmith Exp $
+ */
+
+#include <sys/types.h>
+
+#include <stdlib.h>
+#include <string.h>
+#include <termios.h>
+
+#include "defs.h"
+#include "layer.h"
+#include "mbuf.h"
+#include "log.h"
+#include "timer.h"
+#include "fsm.h"
+#include "lqr.h"
+#include "hdlc.h"
+#include "lcp.h"
+#include "ccp.h"
+#include "throughput.h"
+#include "link.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 HASH(state, x) state->hash = (state->hash << 4) ^ (x)
+#define GUESS_TABLE_SIZE 65536
+
+struct pred1_state {
+ u_short hash;
+ u_char dict[GUESS_TABLE_SIZE];
+};
+
+static int
+compress(struct pred1_state *state, 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 (state->dict[state->hash] == *source) {
+ flags |= bitmask; /* Guess was right - don't output */
+ } else {
+ state->dict[state->hash] = *source;
+ *dest++ = *source; /* Guess wrong, output char */
+ }
+ HASH(state, *source++);
+ len--;
+ }
+ *flagdest = flags;
+ }
+ return (dest - orgdest);
+}
+
+static void
+SyncTable(struct pred1_state *state, u_char *source, u_char *dest, int len)
+{
+ while (len--) {
+ *dest++ = state->dict[state->hash] = *source;
+ HASH(state, *source++);
+ }
+}
+
+static int
+decompress(struct pred1_state *state, 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 = state->dict[state->hash]; /* Guess correct */
+ } else {
+ if (!len)
+ break; /* we seem to be really done -- cabo */
+ state->dict[state->hash] = *source; /* Guess wrong */
+ *dest = *source++; /* Read from source */
+ len--;
+ }
+ HASH(state, *dest++);
+ }
+ }
+ return (dest - orgdest);
+}
+
+static void
+Pred1Term(void *v)
+{
+ struct pred1_state *state = (struct pred1_state *)v;
+ free(state);
+}
+
+static void
+Pred1ResetInput(void *v)
+{
+ struct pred1_state *state = (struct pred1_state *)v;
+ state->hash = 0;
+ memset(state->dict, '\0', sizeof state->dict);
+ log_Printf(LogCCP, "Predictor1: Input channel reset\n");
+}
+
+static int
+Pred1ResetOutput(void *v)
+{
+ struct pred1_state *state = (struct pred1_state *)v;
+ state->hash = 0;
+ memset(state->dict, '\0', sizeof state->dict);
+ log_Printf(LogCCP, "Predictor1: Output channel reset\n");
+
+ return 1; /* Ask FSM to ACK */
+}
+
+static void *
+Pred1InitInput(struct bundle *bundle __unused, struct fsm_opt *o __unused)
+{
+ struct pred1_state *state;
+ state = (struct pred1_state *)malloc(sizeof(struct pred1_state));
+ if (state != NULL)
+ Pred1ResetInput(state);
+ return state;
+}
+
+static void *
+Pred1InitOutput(struct bundle *bundle __unused, struct fsm_opt *o __unused)
+{
+ struct pred1_state *state;
+ state = (struct pred1_state *)malloc(sizeof(struct pred1_state));
+ if (state != NULL)
+ Pred1ResetOutput(state);
+ return state;
+}
+
+static struct mbuf *
+Pred1Output(void *v, struct ccp *ccp, struct link *l __unused,
+ int pri __unused, u_short *proto, struct mbuf *bp)
+{
+ struct pred1_state *state = (struct pred1_state *)v;
+ struct mbuf *mwp;
+ u_char *cp, *wp, *hp;
+ int orglen, len;
+ u_char bufp[MAX_MTU + 2];
+ u_short fcs;
+
+ orglen = m_length(bp) + 2; /* add count of proto */
+ mwp = m_get((orglen + 2) / 8 * 9 + 12, MB_CCPOUT);
+ hp = wp = MBUF_CTOP(mwp);
+ cp = bufp;
+ *wp++ = *cp++ = orglen >> 8;
+ *wp++ = *cp++ = orglen & 0377;
+ *cp++ = *proto >> 8;
+ *cp++ = *proto & 0377;
+ mbuf_Read(bp, cp, orglen - 2);
+ fcs = hdlc_Fcs(bufp, 2 + orglen);
+ fcs = ~fcs;
+
+ len = compress(state, bufp + 2, wp, orglen);
+ log_Printf(LogDEBUG, "Pred1Output: orglen (%d) --> len (%d)\n", orglen, len);
+ ccp->uncompout += orglen;
+ if (len < orglen) {
+ *hp |= 0x80;
+ wp += len;
+ ccp->compout += len;
+ } else {
+ memcpy(wp, bufp + 2, orglen);
+ wp += orglen;
+ ccp->compout += orglen;
+ }
+
+ *wp++ = fcs & 0377;
+ *wp++ = fcs >> 8;
+ mwp->m_len = wp - MBUF_CTOP(mwp);
+ *proto = ccp_Proto(ccp);
+ return mwp;
+}
+
+static struct mbuf *
+Pred1Input(void *v, struct ccp *ccp, u_short *proto, struct mbuf *bp)
+{
+ struct pred1_state *state = (struct pred1_state *)v;
+ u_char *cp, *pp;
+ int len, olen, len1;
+ struct mbuf *wp;
+ u_char *bufp;
+ u_short fcs;
+
+ wp = m_get(MAX_MRU + 2, MB_CCPIN);
+ cp = MBUF_CTOP(bp);
+ olen = m_length(bp);
+ pp = bufp = MBUF_CTOP(wp);
+ *pp++ = *cp & 0177;
+ len = *cp++ << 8;
+ *pp++ = *cp;
+ len += *cp++;
+ ccp->uncompin += len & 0x7fff;
+ if (len & 0x8000) {
+ len1 = decompress(state, cp, pp, olen - 4);
+ ccp->compin += olen;
+ len &= 0x7fff;
+ if (len != len1) { /* Error is detected. Send reset request */
+ log_Printf(LogCCP, "Pred1: Length error (got %d, not %d)\n", len1, len);
+ fsm_Reopen(&ccp->fsm);
+ m_freem(bp);
+ m_freem(wp);
+ return NULL;
+ }
+ cp += olen - 4;
+ pp += len1;
+ } else if (len + 4 != olen) {
+ log_Printf(LogCCP, "Pred1: Length error (got %d, not %d)\n", len + 4, olen);
+ fsm_Reopen(&ccp->fsm);
+ m_freem(wp);
+ m_freem(bp);
+ return NULL;
+ } else {
+ ccp->compin += len;
+ SyncTable(state, cp, pp, len);
+ cp += len;
+ pp += len;
+ }
+ *pp++ = *cp++; /* CRC */
+ *pp++ = *cp++;
+ fcs = hdlc_Fcs(bufp, wp->m_len = pp - bufp);
+ if (fcs == GOODFCS) {
+ wp->m_offset += 2; /* skip length */
+ wp->m_len -= 4; /* skip length & CRC */
+ pp = MBUF_CTOP(wp);
+ *proto = *pp++;
+ if (*proto & 1) {
+ wp->m_offset++;
+ wp->m_len--;
+ } else {
+ wp->m_offset += 2;
+ wp->m_len -= 2;
+ *proto = (*proto << 8) | *pp++;
+ }
+ m_freem(bp);
+ return wp;
+ } else {
+ const char *pre = *MBUF_CTOP(bp) & 0x80 ? "" : "un";
+ log_Printf(LogDEBUG, "Pred1Input: fcs = 0x%04x (%scompressed), len = 0x%x,"
+ " olen = 0x%x\n", fcs, pre, len, olen);
+ log_Printf(LogCCP, "%s: Bad %scompressed CRC-16\n",
+ ccp->fsm.link->name, pre);
+ fsm_Reopen(&ccp->fsm);
+ m_freem(wp);
+ }
+ m_freem(bp);
+ return NULL;
+}
+
+static void
+Pred1DictSetup(void *v __unused, struct ccp *ccp __unused,
+ u_short proto __unused, struct mbuf *bp __unused)
+{
+ /* Nothing to see here */
+}
+
+static const char *
+Pred1DispOpts(struct fsm_opt *o __unused)
+{
+ return NULL;
+}
+
+static void
+Pred1InitOptsOutput(struct bundle *bundle __unused, struct fsm_opt *o,
+ const struct ccp_config *cfg __unused)
+{
+ o->hdr.len = 2;
+}
+
+static int
+Pred1SetOpts(struct bundle *bundle __unused, struct fsm_opt *o,
+ const struct ccp_config *cfg __unused)
+{
+ if (o->hdr.len != 2) {
+ o->hdr.len = 2;
+ return MODE_NAK;
+ }
+ return MODE_ACK;
+}
+
+const struct ccp_algorithm Pred1Algorithm = {
+ TY_PRED1,
+ CCP_NEG_PRED1,
+ Pred1DispOpts,
+ ccp_DefaultUsable,
+ ccp_DefaultRequired,
+ {
+ Pred1SetOpts,
+ Pred1InitInput,
+ Pred1Term,
+ Pred1ResetInput,
+ Pred1Input,
+ Pred1DictSetup
+ },
+ {
+ 0,
+ Pred1InitOptsOutput,
+ Pred1SetOpts,
+ Pred1InitOutput,
+ Pred1Term,
+ Pred1ResetOutput,
+ Pred1Output
+ },
+};
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