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/*-
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* Copyright (c) 1989 The Regents of the University of California.
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 3. All advertising materials mentioning features or use of this software
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* must display the following acknowledgement:
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* This product includes software developed by the University of
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* California, Berkeley and its contributors.
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* 4. Neither the name of the University nor the names of its contributors
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* may be used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*
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* @(#)slcompress.c 7.7 (Berkeley) 5/7/91
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*/
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/*
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* Routines to compress and uncompess tcp packets (for transmission
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* over low speed serial lines.
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*
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* Van Jacobson (van@helios.ee.lbl.gov), Dec 31, 1989:
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* - Initial distribution.
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*
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* $Id: pppcompress.c,v 1.2 2001-09-27 12:01:58 chris Exp $
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*/
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#include <sys/types.h>
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#include <sys/param.h>
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#include <sys/systm.h>
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#include <sys/mbuf.h>
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#include <sys/socket.h>
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#include <sys/socketvar.h>
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#include <netinet/in.h>
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#include <netinet/in_systm.h>
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#include <netinet/ip.h>
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#include <netinet/tcp.h>
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#include <net/pppcompress.h>
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#ifndef SL_NO_STATS
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#define INCR(counter) ++comp->counter;
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#else
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#define INCR(counter)
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#endif
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#define BCMP(p1, p2, n) bcmp((char *)(p1), (char *)(p2), (int)(n))
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#define BCOPY(p1, p2, n) bcopy((char *)(p1), (char *)(p2), (int)(n))
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#ifndef KERNEL
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#define ovbcopy bcopy
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#endif
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void
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vj_compress_init(comp, max_state)
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struct vjcompress *comp;
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int max_state;
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{
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register u_int i;
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register struct cstate *tstate = comp->tstate;
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if ((unsigned) max_state > MAX_STATES - 1)
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max_state = MAX_STATES - 1;
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bzero((char *)comp, sizeof(*comp));
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for (i = max_state; i > 0; --i) {
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tstate[i].cs_id = i;
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tstate[i].cs_next = &tstate[i - 1];
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}
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tstate[0].cs_next = &tstate[max_state];
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tstate[0].cs_id = 0;
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comp->last_cs = &tstate[0];
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comp->last_recv = 255;
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comp->last_xmit = 255;
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comp->flags = SLF_TOSS;
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}
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| 96 |
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/* ENCODE encodes a number that is known to be non-zero. ENCODEZ
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* checks for zero (since zero has to be encoded in the long, 3 byte
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* form).
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*/
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#define ENCODE(n) { \
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if ((u_short)(n) >= 256) { \
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*cp++ = 0; \
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cp[1] = (n); \
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cp[0] = (n) >> 8; \
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cp += 2; \
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} else { \
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*cp++ = (n); \
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} \
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}
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#define ENCODEZ(n) { \
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if ((u_short)(n) >= 256 || (u_short)(n) == 0) { \
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*cp++ = 0; \
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cp[1] = (n); \
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cp[0] = (n) >> 8; \
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cp += 2; \
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} else { \
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*cp++ = (n); \
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} \
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}
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#define DECODEL(f) { \
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if (*cp == 0) {\
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(f) = htonl(ntohl(f) + ((cp[1] << 8) | cp[2])); \
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cp += 3; \
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} else { \
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(f) = htonl(ntohl(f) + (u_long)*cp++); \
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} \
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}
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| 130 |
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#define DECODES(f) { \
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if (*cp == 0) {\
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(f) = htons(ntohs(f) + ((cp[1] << 8) | cp[2])); \
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cp += 3; \
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} else { \
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(f) = htons(ntohs(f) + (u_long)*cp++); \
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} \
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}
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| 139 |
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#define DECODEU(f) { \
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if (*cp == 0) {\
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(f) = htons((cp[1] << 8) | cp[2]); \
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cp += 3; \
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} else { \
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(f) = htons((u_long)*cp++); \
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} \
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}
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u_int
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vj_compress_tcp(m, ip, comp, compress_cid)
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struct mbuf *m;
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register struct ip *ip;
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struct vjcompress *comp;
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int compress_cid;
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{
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register struct cstate *cs = comp->last_cs->cs_next;
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register u_int hlen = ip->ip_hl;
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register struct tcphdr *oth;
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register struct tcphdr *th;
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register u_int deltaS, deltaA;
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register u_int changes = 0;
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u_char new_seq[16];
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register u_char *cp = new_seq;
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/*
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* Bail if this is an IP fragment or if the TCP packet isn't
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* `compressible' (i.e., ACK isn't set or some other control bit is
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* set). (We assume that the caller has already made sure the
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* packet is IP proto TCP).
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*/
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if ((ip->ip_off & htons(0x3fff)) || m->m_len < 40)
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return (TYPE_IP);
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| 173 |
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th = (struct tcphdr *)&((int *)ip)[hlen];
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if ((th->th_flags & (TH_SYN|TH_FIN|TH_RST|TH_ACK)) != TH_ACK)
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return (TYPE_IP);
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/*
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* Packet is compressible -- we're going to send either a
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* COMPRESSED_TCP or UNCOMPRESSED_TCP packet. Either way we need
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| 179 |
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* to locate (or create) the connection state. Special case the
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| 180 |
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* most recently used connection since it's most likely to be used
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* again & we don't have to do any reordering if it's used.
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*/
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INCR(sls_packets)
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if (ip->ip_src.s_addr != cs->cs_ip.ip_src.s_addr ||
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ip->ip_dst.s_addr != cs->cs_ip.ip_dst.s_addr ||
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| 186 |
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*(int *)th != ((int *)&cs->cs_ip)[cs->cs_ip.ip_hl]) {
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| 187 |
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/*
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| 188 |
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* Wasn't the first -- search for it.
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| 189 |
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*
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| 190 |
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* States are kept in a circularly linked list with
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| 191 |
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* last_cs pointing to the end of the list. The
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| 192 |
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* list is kept in lru order by moving a state to the
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| 193 |
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* head of the list whenever it is referenced. Since
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| 194 |
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* the list is short and, empirically, the connection
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| 195 |
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* we want is almost always near the front, we locate
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| 196 |
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* states via linear search. If we don't find a state
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| 197 |
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* for the datagram, the oldest state is (re-)used.
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| 198 |
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*/
|
| 199 |
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register struct cstate *lcs;
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| 200 |
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register struct cstate *lastcs = comp->last_cs;
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| 201 |
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|
| 202 |
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do {
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| 203 |
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lcs = cs; cs = cs->cs_next;
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| 204 |
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INCR(sls_searches)
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| 205 |
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if (ip->ip_src.s_addr == cs->cs_ip.ip_src.s_addr
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| 206 |
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&& ip->ip_dst.s_addr == cs->cs_ip.ip_dst.s_addr
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| 207 |
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&& *(int *)th == ((int *)&cs->cs_ip)[cs->cs_ip.ip_hl])
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| 208 |
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goto found;
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| 209 |
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} while (cs != lastcs);
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| 210 |
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|
| 211 |
|
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/*
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| 212 |
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* Didn't find it -- re-use oldest cstate. Send an
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| 213 |
|
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* uncompressed packet that tells the other side what
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| 214 |
|
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* connection number we're using for this conversation.
|
| 215 |
|
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* Note that since the state list is circular, the oldest
|
| 216 |
|
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* state points to the newest and we only need to set
|
| 217 |
|
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* last_cs to update the lru linkage.
|
| 218 |
|
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*/
|
| 219 |
|
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INCR(sls_misses)
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| 220 |
|
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comp->last_cs = lcs;
|
| 221 |
|
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hlen += th->th_off;
|
| 222 |
|
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hlen <<= 2;
|
| 223 |
|
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goto uncompressed;
|
| 224 |
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|
|
| 225 |
|
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found:
|
| 226 |
|
|
/*
|
| 227 |
|
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* Found it -- move to the front on the connection list.
|
| 228 |
|
|
*/
|
| 229 |
|
|
if (cs == lastcs)
|
| 230 |
|
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comp->last_cs = lcs;
|
| 231 |
|
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else {
|
| 232 |
|
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lcs->cs_next = cs->cs_next;
|
| 233 |
|
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cs->cs_next = lastcs->cs_next;
|
| 234 |
|
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lastcs->cs_next = cs;
|
| 235 |
|
|
}
|
| 236 |
|
|
}
|
| 237 |
|
|
|
| 238 |
|
|
/*
|
| 239 |
|
|
* Make sure that only what we expect to change changed. The first
|
| 240 |
|
|
* line of the `if' checks the IP protocol version, header length &
|
| 241 |
|
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* type of service. The 2nd line checks the "Don't fragment" bit.
|
| 242 |
|
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* The 3rd line checks the time-to-live and protocol (the protocol
|
| 243 |
|
|
* check is unnecessary but costless). The 4th line checks the TCP
|
| 244 |
|
|
* header length. The 5th line checks IP options, if any. The 6th
|
| 245 |
|
|
* line checks TCP options, if any. If any of these things are
|
| 246 |
|
|
* different between the previous & current datagram, we send the
|
| 247 |
|
|
* current datagram `uncompressed'.
|
| 248 |
|
|
*/
|
| 249 |
|
|
oth = (struct tcphdr *)&((int *)&cs->cs_ip)[hlen];
|
| 250 |
|
|
deltaS = hlen;
|
| 251 |
|
|
hlen += th->th_off;
|
| 252 |
|
|
hlen <<= 2;
|
| 253 |
|
|
|
| 254 |
|
|
if (((u_short *)ip)[0] != ((u_short *)&cs->cs_ip)[0] ||
|
| 255 |
|
|
((u_short *)ip)[3] != ((u_short *)&cs->cs_ip)[3] ||
|
| 256 |
|
|
((u_short *)ip)[4] != ((u_short *)&cs->cs_ip)[4] ||
|
| 257 |
|
|
th->th_off != oth->th_off ||
|
| 258 |
|
|
(deltaS > 5 &&
|
| 259 |
|
|
BCMP(ip + 1, &cs->cs_ip + 1, (deltaS - 5) << 2)) ||
|
| 260 |
|
|
(th->th_off > 5 &&
|
| 261 |
|
|
BCMP(th + 1, oth + 1, (th->th_off - 5) << 2)))
|
| 262 |
|
|
goto uncompressed;
|
| 263 |
|
|
|
| 264 |
|
|
/*
|
| 265 |
|
|
* Figure out which of the changing fields changed. The
|
| 266 |
|
|
* receiver expects changes in the order: urgent, window,
|
| 267 |
|
|
* ack, seq (the order minimizes the number of temporaries
|
| 268 |
|
|
* needed in this section of code).
|
| 269 |
|
|
*/
|
| 270 |
|
|
if (th->th_flags & TH_URG) {
|
| 271 |
|
|
deltaS = ntohs(th->th_urp);
|
| 272 |
|
|
ENCODEZ(deltaS);
|
| 273 |
|
|
changes |= NEW_U;
|
| 274 |
|
|
} else if (th->th_urp != oth->th_urp)
|
| 275 |
|
|
/* argh! URG not set but urp changed -- a sensible
|
| 276 |
|
|
* implementation should never do this but RFC793
|
| 277 |
|
|
* doesn't prohibit the change so we have to deal
|
| 278 |
|
|
* with it. */
|
| 279 |
|
|
goto uncompressed;
|
| 280 |
|
|
|
| 281 |
|
|
if (deltaS = (u_short)(ntohs(th->th_win) - ntohs(oth->th_win))) {
|
| 282 |
|
|
ENCODE(deltaS);
|
| 283 |
|
|
changes |= NEW_W;
|
| 284 |
|
|
}
|
| 285 |
|
|
|
| 286 |
|
|
if (deltaA = ntohl(th->th_ack) - ntohl(oth->th_ack)) {
|
| 287 |
|
|
if (deltaA > 0xffff)
|
| 288 |
|
|
goto uncompressed;
|
| 289 |
|
|
ENCODE(deltaA);
|
| 290 |
|
|
changes |= NEW_A;
|
| 291 |
|
|
}
|
| 292 |
|
|
|
| 293 |
|
|
if (deltaS = ntohl(th->th_seq) - ntohl(oth->th_seq)) {
|
| 294 |
|
|
if (deltaS > 0xffff)
|
| 295 |
|
|
goto uncompressed;
|
| 296 |
|
|
ENCODE(deltaS);
|
| 297 |
|
|
changes |= NEW_S;
|
| 298 |
|
|
}
|
| 299 |
|
|
|
| 300 |
|
|
switch(changes) {
|
| 301 |
|
|
|
| 302 |
|
|
case 0:
|
| 303 |
|
|
/*
|
| 304 |
|
|
* Nothing changed. If this packet contains data and the
|
| 305 |
|
|
* last one didn't, this is probably a data packet following
|
| 306 |
|
|
* an ack (normal on an interactive connection) and we send
|
| 307 |
|
|
* it compressed. Otherwise it's probably a retransmit,
|
| 308 |
|
|
* retransmitted ack or window probe. Send it uncompressed
|
| 309 |
|
|
* in case the other side missed the compressed version.
|
| 310 |
|
|
*/
|
| 311 |
|
|
if (ip->ip_len != cs->cs_ip.ip_len &&
|
| 312 |
|
|
ntohs(cs->cs_ip.ip_len) == hlen)
|
| 313 |
|
|
break;
|
| 314 |
|
|
|
| 315 |
|
|
/* (fall through) */
|
| 316 |
|
|
|
| 317 |
|
|
case SPECIAL_I:
|
| 318 |
|
|
case SPECIAL_D:
|
| 319 |
|
|
/*
|
| 320 |
|
|
* actual changes match one of our special case encodings --
|
| 321 |
|
|
* send packet uncompressed.
|
| 322 |
|
|
*/
|
| 323 |
|
|
goto uncompressed;
|
| 324 |
|
|
|
| 325 |
|
|
case NEW_S|NEW_A:
|
| 326 |
|
|
if (deltaS == deltaA &&
|
| 327 |
|
|
deltaS == ntohs(cs->cs_ip.ip_len) - hlen) {
|
| 328 |
|
|
/* special case for echoed terminal traffic */
|
| 329 |
|
|
changes = SPECIAL_I;
|
| 330 |
|
|
cp = new_seq;
|
| 331 |
|
|
}
|
| 332 |
|
|
break;
|
| 333 |
|
|
|
| 334 |
|
|
case NEW_S:
|
| 335 |
|
|
if (deltaS == ntohs(cs->cs_ip.ip_len) - hlen) {
|
| 336 |
|
|
/* special case for data xfer */
|
| 337 |
|
|
changes = SPECIAL_D;
|
| 338 |
|
|
cp = new_seq;
|
| 339 |
|
|
}
|
| 340 |
|
|
break;
|
| 341 |
|
|
}
|
| 342 |
|
|
|
| 343 |
|
|
deltaS = ntohs(ip->ip_id) - ntohs(cs->cs_ip.ip_id);
|
| 344 |
|
|
if (deltaS != 1) {
|
| 345 |
|
|
ENCODEZ(deltaS);
|
| 346 |
|
|
changes |= NEW_I;
|
| 347 |
|
|
}
|
| 348 |
|
|
if (th->th_flags & TH_PUSH)
|
| 349 |
|
|
changes |= TCP_PUSH_BIT;
|
| 350 |
|
|
/*
|
| 351 |
|
|
* Grab the cksum before we overwrite it below. Then update our
|
| 352 |
|
|
* state with this packet's header.
|
| 353 |
|
|
*/
|
| 354 |
|
|
deltaA = ntohs(th->th_sum);
|
| 355 |
|
|
BCOPY(ip, &cs->cs_ip, hlen);
|
| 356 |
|
|
|
| 357 |
|
|
/*
|
| 358 |
|
|
* We want to use the original packet as our compressed packet.
|
| 359 |
|
|
* (cp - new_seq) is the number of bytes we need for compressed
|
| 360 |
|
|
* sequence numbers. In addition we need one byte for the change
|
| 361 |
|
|
* mask, one for the connection id and two for the tcp checksum.
|
| 362 |
|
|
* So, (cp - new_seq) + 4 bytes of header are needed. hlen is how
|
| 363 |
|
|
* many bytes of the original packet to toss so subtract the two to
|
| 364 |
|
|
* get the new packet size.
|
| 365 |
|
|
*/
|
| 366 |
|
|
deltaS = cp - new_seq;
|
| 367 |
|
|
cp = (u_char *)ip;
|
| 368 |
|
|
if (compress_cid == 0 || comp->last_xmit != cs->cs_id) {
|
| 369 |
|
|
comp->last_xmit = cs->cs_id;
|
| 370 |
|
|
hlen -= deltaS + 4;
|
| 371 |
|
|
cp += hlen;
|
| 372 |
|
|
*cp++ = changes | NEW_C;
|
| 373 |
|
|
*cp++ = cs->cs_id;
|
| 374 |
|
|
} else {
|
| 375 |
|
|
hlen -= deltaS + 3;
|
| 376 |
|
|
cp += hlen;
|
| 377 |
|
|
*cp++ = changes;
|
| 378 |
|
|
}
|
| 379 |
|
|
m->m_len -= hlen;
|
| 380 |
|
|
m->m_data += hlen;
|
| 381 |
|
|
*cp++ = deltaA >> 8;
|
| 382 |
|
|
*cp++ = deltaA;
|
| 383 |
|
|
BCOPY(new_seq, cp, deltaS);
|
| 384 |
|
|
INCR(sls_compressed)
|
| 385 |
|
|
return (TYPE_COMPRESSED_TCP);
|
| 386 |
|
|
|
| 387 |
|
|
/*
|
| 388 |
|
|
* Update connection state cs & send uncompressed packet ('uncompressed'
|
| 389 |
|
|
* means a regular ip/tcp packet but with the 'conversation id' we hope
|
| 390 |
|
|
* to use on future compressed packets in the protocol field).
|
| 391 |
|
|
*/
|
| 392 |
|
|
uncompressed:
|
| 393 |
|
|
BCOPY(ip, &cs->cs_ip, hlen);
|
| 394 |
|
|
ip->ip_p = cs->cs_id;
|
| 395 |
|
|
comp->last_xmit = cs->cs_id;
|
| 396 |
|
|
return (TYPE_UNCOMPRESSED_TCP);
|
| 397 |
|
|
}
|
| 398 |
|
|
|
| 399 |
|
|
|
| 400 |
|
|
int
|
| 401 |
|
|
vj_uncompress_tcp(bufp, len, type, comp)
|
| 402 |
|
|
u_char **bufp;
|
| 403 |
|
|
int len;
|
| 404 |
|
|
u_int type;
|
| 405 |
|
|
struct vjcompress *comp;
|
| 406 |
|
|
{
|
| 407 |
|
|
u_char *hdr, *cp;
|
| 408 |
|
|
int hlen, vjlen;
|
| 409 |
|
|
|
| 410 |
|
|
cp = bufp? *bufp: NULL;
|
| 411 |
|
|
vjlen = vj_uncompress_tcp_core(cp, len, len, type, comp, &hdr, &hlen);
|
| 412 |
|
|
if (vjlen < 0)
|
| 413 |
|
|
return (0); /* error */
|
| 414 |
|
|
if (vjlen == 0)
|
| 415 |
|
|
return (len); /* was uncompressed already */
|
| 416 |
|
|
|
| 417 |
|
|
cp += vjlen;
|
| 418 |
|
|
len -= vjlen;
|
| 419 |
|
|
|
| 420 |
|
|
/*
|
| 421 |
|
|
* At this point, cp points to the first byte of data in the
|
| 422 |
|
|
* packet. If we're not aligned on a 4-byte boundary, copy the
|
| 423 |
|
|
* data down so the ip & tcp headers will be aligned. Then back up
|
| 424 |
|
|
* cp by the tcp/ip header length to make room for the reconstructed
|
| 425 |
|
|
* header (we assume the packet we were handed has enough space to
|
| 426 |
|
|
* prepend 128 bytes of header).
|
| 427 |
|
|
*/
|
| 428 |
|
|
if ((int)cp & 3) {
|
| 429 |
|
|
if (len > 0)
|
| 430 |
|
|
(void) ovbcopy(cp, (caddr_t)((int)cp &~ 3), len);
|
| 431 |
|
|
cp = (u_char *)((int)cp &~ 3);
|
| 432 |
|
|
}
|
| 433 |
|
|
cp -= hlen;
|
| 434 |
|
|
len += hlen;
|
| 435 |
|
|
BCOPY(hdr, cp, hlen);
|
| 436 |
|
|
|
| 437 |
|
|
*bufp = cp;
|
| 438 |
|
|
return (len);
|
| 439 |
|
|
}
|
| 440 |
|
|
|
| 441 |
|
|
/*
|
| 442 |
|
|
* Uncompress a packet of total length total_len. The first buflen
|
| 443 |
|
|
* bytes are at buf; this must include the entire (compressed or
|
| 444 |
|
|
* uncompressed) TCP/IP header. This procedure returns the length
|
| 445 |
|
|
* of the VJ header, with a pointer to the uncompressed IP header
|
| 446 |
|
|
* in *hdrp and its length in *hlenp.
|
| 447 |
|
|
*/
|
| 448 |
|
|
int
|
| 449 |
|
|
vj_uncompress_tcp_core(buf, buflen, total_len, type, comp, hdrp, hlenp)
|
| 450 |
|
|
u_char *buf;
|
| 451 |
|
|
int buflen, total_len;
|
| 452 |
|
|
u_int type;
|
| 453 |
|
|
struct vjcompress *comp;
|
| 454 |
|
|
u_char **hdrp;
|
| 455 |
|
|
u_int *hlenp;
|
| 456 |
|
|
{
|
| 457 |
|
|
register u_char *cp;
|
| 458 |
|
|
register u_int hlen, changes;
|
| 459 |
|
|
register struct tcphdr *th;
|
| 460 |
|
|
register struct cstate *cs;
|
| 461 |
|
|
register struct ip *ip;
|
| 462 |
|
|
register u_short *bp;
|
| 463 |
|
|
register u_int vjlen;
|
| 464 |
|
|
|
| 465 |
|
|
switch (type) {
|
| 466 |
|
|
|
| 467 |
|
|
case TYPE_UNCOMPRESSED_TCP:
|
| 468 |
|
|
ip = (struct ip *) buf;
|
| 469 |
|
|
if (ip->ip_p >= MAX_STATES)
|
| 470 |
|
|
goto bad;
|
| 471 |
|
|
cs = &comp->rstate[comp->last_recv = ip->ip_p];
|
| 472 |
|
|
comp->flags &=~ SLF_TOSS;
|
| 473 |
|
|
ip->ip_p = IPPROTO_TCP;
|
| 474 |
|
|
/*
|
| 475 |
|
|
* Calculate the size of the TCP/IP header and make sure that
|
| 476 |
|
|
* we don't overflow the space we have available for it.
|
| 477 |
|
|
*/
|
| 478 |
|
|
hlen = ip->ip_hl << 2;
|
| 479 |
|
|
if (hlen + sizeof(struct tcphdr) > buflen)
|
| 480 |
|
|
goto bad;
|
| 481 |
|
|
hlen += ((struct tcphdr *)&((char *)ip)[hlen])->th_off << 2;
|
| 482 |
|
|
if (hlen > MAX_HDR || hlen > buflen)
|
| 483 |
|
|
goto bad;
|
| 484 |
|
|
BCOPY(ip, &cs->cs_ip, hlen);
|
| 485 |
|
|
cs->cs_hlen = hlen;
|
| 486 |
|
|
INCR(sls_uncompressedin)
|
| 487 |
|
|
*hdrp = (u_char *) &cs->cs_ip;
|
| 488 |
|
|
*hlenp = hlen;
|
| 489 |
|
|
return (0);
|
| 490 |
|
|
|
| 491 |
|
|
default:
|
| 492 |
|
|
goto bad;
|
| 493 |
|
|
|
| 494 |
|
|
case TYPE_COMPRESSED_TCP:
|
| 495 |
|
|
break;
|
| 496 |
|
|
}
|
| 497 |
|
|
/* We've got a compressed packet. */
|
| 498 |
|
|
INCR(sls_compressedin)
|
| 499 |
|
|
cp = buf;
|
| 500 |
|
|
changes = *cp++;
|
| 501 |
|
|
if (changes & NEW_C) {
|
| 502 |
|
|
/* Make sure the state index is in range, then grab the state.
|
| 503 |
|
|
* If we have a good state index, clear the 'discard' flag. */
|
| 504 |
|
|
if (*cp >= MAX_STATES)
|
| 505 |
|
|
goto bad;
|
| 506 |
|
|
|
| 507 |
|
|
comp->flags &=~ SLF_TOSS;
|
| 508 |
|
|
comp->last_recv = *cp++;
|
| 509 |
|
|
} else {
|
| 510 |
|
|
/* this packet has an implicit state index. If we've
|
| 511 |
|
|
* had a line error since the last time we got an
|
| 512 |
|
|
* explicit state index, we have to toss the packet. */
|
| 513 |
|
|
if (comp->flags & SLF_TOSS) {
|
| 514 |
|
|
INCR(sls_tossed)
|
| 515 |
|
|
return (-1);
|
| 516 |
|
|
}
|
| 517 |
|
|
}
|
| 518 |
|
|
cs = &comp->rstate[comp->last_recv];
|
| 519 |
|
|
hlen = cs->cs_ip.ip_hl << 2;
|
| 520 |
|
|
th = (struct tcphdr *)&((u_char *)&cs->cs_ip)[hlen];
|
| 521 |
|
|
th->th_sum = htons((*cp << 8) | cp[1]);
|
| 522 |
|
|
cp += 2;
|
| 523 |
|
|
if (changes & TCP_PUSH_BIT)
|
| 524 |
|
|
th->th_flags |= TH_PUSH;
|
| 525 |
|
|
else
|
| 526 |
|
|
th->th_flags &=~ TH_PUSH;
|
| 527 |
|
|
|
| 528 |
|
|
switch (changes & SPECIALS_MASK) {
|
| 529 |
|
|
case SPECIAL_I:
|
| 530 |
|
|
{
|
| 531 |
|
|
register u_int i = ntohs(cs->cs_ip.ip_len) - cs->cs_hlen;
|
| 532 |
|
|
th->th_ack = htonl(ntohl(th->th_ack) + i);
|
| 533 |
|
|
th->th_seq = htonl(ntohl(th->th_seq) + i);
|
| 534 |
|
|
}
|
| 535 |
|
|
break;
|
| 536 |
|
|
|
| 537 |
|
|
case SPECIAL_D:
|
| 538 |
|
|
th->th_seq = htonl(ntohl(th->th_seq) + ntohs(cs->cs_ip.ip_len)
|
| 539 |
|
|
- cs->cs_hlen);
|
| 540 |
|
|
break;
|
| 541 |
|
|
|
| 542 |
|
|
default:
|
| 543 |
|
|
if (changes & NEW_U) {
|
| 544 |
|
|
th->th_flags |= TH_URG;
|
| 545 |
|
|
DECODEU(th->th_urp)
|
| 546 |
|
|
} else
|
| 547 |
|
|
th->th_flags &=~ TH_URG;
|
| 548 |
|
|
if (changes & NEW_W)
|
| 549 |
|
|
DECODES(th->th_win)
|
| 550 |
|
|
if (changes & NEW_A)
|
| 551 |
|
|
DECODEL(th->th_ack)
|
| 552 |
|
|
if (changes & NEW_S)
|
| 553 |
|
|
DECODEL(th->th_seq)
|
| 554 |
|
|
break;
|
| 555 |
|
|
}
|
| 556 |
|
|
if (changes & NEW_I) {
|
| 557 |
|
|
DECODES(cs->cs_ip.ip_id)
|
| 558 |
|
|
} else
|
| 559 |
|
|
cs->cs_ip.ip_id = htons(ntohs(cs->cs_ip.ip_id) + 1);
|
| 560 |
|
|
|
| 561 |
|
|
/*
|
| 562 |
|
|
* At this point, cp points to the first byte of data in the
|
| 563 |
|
|
* packet. Fill in the IP total length and update the IP
|
| 564 |
|
|
* header checksum.
|
| 565 |
|
|
*/
|
| 566 |
|
|
vjlen = cp - buf;
|
| 567 |
|
|
buflen -= vjlen;
|
| 568 |
|
|
if (buflen < 0)
|
| 569 |
|
|
/* we must have dropped some characters (crc should detect
|
| 570 |
|
|
* this but the old slip framing won't) */
|
| 571 |
|
|
goto bad;
|
| 572 |
|
|
|
| 573 |
|
|
total_len += cs->cs_hlen - vjlen;
|
| 574 |
|
|
cs->cs_ip.ip_len = htons(total_len);
|
| 575 |
|
|
|
| 576 |
|
|
/* recompute the ip header checksum */
|
| 577 |
|
|
bp = (u_short *) &cs->cs_ip;
|
| 578 |
|
|
cs->cs_ip.ip_sum = 0;
|
| 579 |
|
|
for (changes = 0; hlen > 0; hlen -= 2)
|
| 580 |
|
|
changes += *bp++;
|
| 581 |
|
|
changes = (changes & 0xffff) + (changes >> 16);
|
| 582 |
|
|
changes = (changes & 0xffff) + (changes >> 16);
|
| 583 |
|
|
cs->cs_ip.ip_sum = ~ changes;
|
| 584 |
|
|
|
| 585 |
|
|
*hdrp = (u_char *) &cs->cs_ip;
|
| 586 |
|
|
*hlenp = cs->cs_hlen;
|
| 587 |
|
|
return vjlen;
|
| 588 |
|
|
|
| 589 |
|
|
bad:
|
| 590 |
|
|
comp->flags |= SLF_TOSS;
|
| 591 |
|
|
INCR(sls_errorin)
|
| 592 |
|
|
return (-1);
|
| 593 |
|
|
}
|
