585 lines
16 KiB
C
585 lines
16 KiB
C
/*
|
|
* Routines to compress and uncompess tcp packets (for transmission
|
|
* over low speed serial lines.
|
|
*
|
|
* Copyright (c) 1989 Regents of the University of California.
|
|
* All rights reserved.
|
|
*
|
|
* Redistribution and use in source and binary forms are permitted
|
|
* provided that the above copyright notice and this paragraph are
|
|
* duplicated in all such forms and that any documentation,
|
|
* advertising materials, and other materials related to such
|
|
* distribution and use acknowledge that the software was developed
|
|
* by the University of California, Berkeley. The name of the
|
|
* University may not be used to endorse or promote products derived
|
|
* from this software without specific prior written permission.
|
|
* THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR
|
|
* IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED
|
|
* WARRANTIES OF MERCHANTIBILITY AND FITNESS FOR A PARTICULAR PURPOSE.
|
|
*
|
|
* $FreeBSD$
|
|
*
|
|
* Van Jacobson (van@helios.ee.lbl.gov), Dec 31, 1989:
|
|
* - Initial distribution.
|
|
*/
|
|
|
|
#include <sys/param.h>
|
|
#include <netinet/in_systm.h>
|
|
#include <netinet/in.h>
|
|
#include <netinet/tcp.h>
|
|
#include <netinet/ip.h>
|
|
#include <sys/un.h>
|
|
|
|
#include <stdio.h>
|
|
#include <string.h>
|
|
#include <termios.h>
|
|
|
|
#include "layer.h"
|
|
#include "defs.h"
|
|
#include "command.h"
|
|
#include "mbuf.h"
|
|
#include "log.h"
|
|
#include "slcompress.h"
|
|
#include "descriptor.h"
|
|
#include "prompt.h"
|
|
#include "timer.h"
|
|
#include "fsm.h"
|
|
#include "throughput.h"
|
|
#include "iplist.h"
|
|
#include "lqr.h"
|
|
#include "hdlc.h"
|
|
#include "ipcp.h"
|
|
#include "filter.h"
|
|
#include "lcp.h"
|
|
#include "ccp.h"
|
|
#include "link.h"
|
|
#include "mp.h"
|
|
#ifndef NORADIUS
|
|
#include "radius.h"
|
|
#endif
|
|
#include "bundle.h"
|
|
|
|
void
|
|
sl_compress_init(struct slcompress *comp, int max_state)
|
|
{
|
|
register u_int i;
|
|
register struct cstate *tstate = comp->tstate;
|
|
|
|
memset(comp, '\0', sizeof *comp);
|
|
for (i = max_state; i > 0; --i) {
|
|
tstate[i].cs_id = i;
|
|
tstate[i].cs_next = &tstate[i - 1];
|
|
}
|
|
tstate[0].cs_next = &tstate[max_state];
|
|
tstate[0].cs_id = 0;
|
|
comp->last_cs = &tstate[0];
|
|
comp->last_recv = 255;
|
|
comp->last_xmit = 255;
|
|
comp->flags = SLF_TOSS;
|
|
}
|
|
|
|
|
|
/* ENCODE encodes a number that is known to be non-zero. ENCODEZ
|
|
* checks for zero (since zero has to be encoded in the 32-bit, 3 byte
|
|
* form).
|
|
*/
|
|
#define ENCODE(n) { \
|
|
if ((u_short)(n) >= 256) { \
|
|
*cp++ = 0; \
|
|
cp[1] = (n); \
|
|
cp[0] = (n) >> 8; \
|
|
cp += 2; \
|
|
} else { \
|
|
*cp++ = (n); \
|
|
} \
|
|
}
|
|
#define ENCODEZ(n) { \
|
|
if ((u_short)(n) >= 256 || (u_short)(n) == 0) { \
|
|
*cp++ = 0; \
|
|
cp[1] = (n); \
|
|
cp[0] = (n) >> 8; \
|
|
cp += 2; \
|
|
} else { \
|
|
*cp++ = (n); \
|
|
} \
|
|
}
|
|
|
|
#define DECODEL(f) { \
|
|
if (*cp == 0) {\
|
|
(f) = htonl(ntohl(f) + ((cp[1] << 8) | cp[2])); \
|
|
cp += 3; \
|
|
} else { \
|
|
(f) = htonl(ntohl(f) + (u_int32_t)*cp++); \
|
|
} \
|
|
}
|
|
|
|
#define DECODES(f) { \
|
|
if (*cp == 0) {\
|
|
(f) = htons(ntohs(f) + ((cp[1] << 8) | cp[2])); \
|
|
cp += 3; \
|
|
} else { \
|
|
(f) = htons(ntohs(f) + (u_int32_t)*cp++); \
|
|
} \
|
|
}
|
|
|
|
#define DECODEU(f) { \
|
|
if (*cp == 0) {\
|
|
(f) = htons((cp[1] << 8) | cp[2]); \
|
|
cp += 3; \
|
|
} else { \
|
|
(f) = htons((u_int32_t)*cp++); \
|
|
} \
|
|
}
|
|
|
|
|
|
u_char
|
|
sl_compress_tcp(struct mbuf * m,
|
|
struct ip * ip,
|
|
struct slcompress *comp,
|
|
struct slstat *slstat,
|
|
int compress_cid)
|
|
{
|
|
register struct cstate *cs = comp->last_cs->cs_next;
|
|
register u_int hlen = ip->ip_hl;
|
|
register struct tcphdr *oth;
|
|
register struct tcphdr *th;
|
|
register u_int deltaS, deltaA;
|
|
register u_int changes = 0;
|
|
u_char new_seq[16];
|
|
register u_char *cp = new_seq;
|
|
|
|
/*
|
|
* Bail if this is an IP fragment or if the TCP packet isn't `compressible'
|
|
* (i.e., ACK isn't set or some other control bit is set). (We assume that
|
|
* the caller has already made sure the packet is IP proto TCP).
|
|
*/
|
|
if ((ip->ip_off & htons(0x3fff)) || m->m_len < 40) {
|
|
log_Printf(LogDEBUG, "??? 1 ip_off = %x, m_len = %lu\n",
|
|
ip->ip_off, (unsigned long)m->m_len);
|
|
log_DumpBp(LogDEBUG, "", m);
|
|
return (TYPE_IP);
|
|
}
|
|
th = (struct tcphdr *) & ((int *) ip)[hlen];
|
|
if ((th->th_flags & (TH_SYN | TH_FIN | TH_RST | TH_ACK)) != TH_ACK) {
|
|
log_Printf(LogDEBUG, "??? 2 th_flags = %x\n", th->th_flags);
|
|
log_DumpBp(LogDEBUG, "", m);
|
|
return (TYPE_IP);
|
|
}
|
|
|
|
/*
|
|
* Packet is compressible -- we're going to send either a COMPRESSED_TCP or
|
|
* UNCOMPRESSED_TCP packet. Either way we need to locate (or create) the
|
|
* connection state. Special case the most recently used connection since
|
|
* it's most likely to be used again & we don't have to do any reordering
|
|
* if it's used.
|
|
*/
|
|
slstat->sls_packets++;
|
|
if (ip->ip_src.s_addr != cs->cs_ip.ip_src.s_addr ||
|
|
ip->ip_dst.s_addr != cs->cs_ip.ip_dst.s_addr ||
|
|
*(int *) th != ((int *) &cs->cs_ip)[cs->cs_ip.ip_hl]) {
|
|
|
|
/*
|
|
* Wasn't the first -- search for it.
|
|
*
|
|
* States are kept in a circularly linked list with last_cs pointing to the
|
|
* end of the list. The list is kept in lru order by moving a state to
|
|
* the head of the list whenever it is referenced. Since the list is
|
|
* short and, empirically, the connection we want is almost always near
|
|
* the front, we locate states via linear search. If we don't find a
|
|
* state for the datagram, the oldest state is (re-)used.
|
|
*/
|
|
register struct cstate *lcs;
|
|
register struct cstate *lastcs = comp->last_cs;
|
|
|
|
do {
|
|
lcs = cs;
|
|
cs = cs->cs_next;
|
|
slstat->sls_searches++;
|
|
if (ip->ip_src.s_addr == cs->cs_ip.ip_src.s_addr
|
|
&& ip->ip_dst.s_addr == cs->cs_ip.ip_dst.s_addr
|
|
&& *(int *) th == ((int *) &cs->cs_ip)[cs->cs_ip.ip_hl])
|
|
goto found;
|
|
} while (cs != lastcs);
|
|
|
|
/*
|
|
* Didn't find it -- re-use oldest cstate. Send an uncompressed packet
|
|
* that tells the other side what connection number we're using for this
|
|
* conversation. Note that since the state list is circular, the oldest
|
|
* state points to the newest and we only need to set last_cs to update
|
|
* the lru linkage.
|
|
*/
|
|
slstat->sls_misses++;
|
|
comp->last_cs = lcs;
|
|
#define THOFFSET(th) (th->th_off)
|
|
hlen += th->th_off;
|
|
hlen <<= 2;
|
|
if (hlen > m->m_len)
|
|
return (TYPE_IP);
|
|
goto uncompressed;
|
|
|
|
found:
|
|
|
|
/*
|
|
* Found it -- move to the front on the connection list.
|
|
*/
|
|
if (cs == lastcs)
|
|
comp->last_cs = lcs;
|
|
else {
|
|
lcs->cs_next = cs->cs_next;
|
|
cs->cs_next = lastcs->cs_next;
|
|
lastcs->cs_next = cs;
|
|
}
|
|
}
|
|
|
|
/*
|
|
* Make sure that only what we expect to change changed. The first line of
|
|
* the `if' checks the IP protocol version, header length & type of
|
|
* service. The 2nd line checks the "Don't fragment" bit. The 3rd line
|
|
* checks the time-to-live and protocol (the protocol check is unnecessary
|
|
* but costless). The 4th line checks the TCP header length. The 5th line
|
|
* checks IP options, if any. The 6th line checks TCP options, if any. If
|
|
* any of these things are different between the previous & current
|
|
* datagram, we send the current datagram `uncompressed'.
|
|
*/
|
|
oth = (struct tcphdr *) & ((int *) &cs->cs_ip)[hlen];
|
|
deltaS = hlen;
|
|
hlen += th->th_off;
|
|
hlen <<= 2;
|
|
if (hlen > m->m_len)
|
|
return (TYPE_IP);
|
|
|
|
if (((u_short *) ip)[0] != ((u_short *) & cs->cs_ip)[0] ||
|
|
((u_short *) ip)[3] != ((u_short *) & cs->cs_ip)[3] ||
|
|
((u_short *) ip)[4] != ((u_short *) & cs->cs_ip)[4] ||
|
|
THOFFSET(th) != THOFFSET(oth) ||
|
|
(deltaS > 5 &&
|
|
memcmp(ip + 1, &cs->cs_ip + 1, (deltaS - 5) << 2)) ||
|
|
(THOFFSET(th) > 5 &&
|
|
memcmp(th + 1, oth + 1, (THOFFSET(th) - 5) << 2))) {
|
|
goto uncompressed;
|
|
}
|
|
|
|
/*
|
|
* Figure out which of the changing fields changed. The receiver expects
|
|
* changes in the order: urgent, window, ack, seq (the order minimizes the
|
|
* number of temporaries needed in this section of code).
|
|
*/
|
|
if (th->th_flags & TH_URG) {
|
|
deltaS = ntohs(th->th_urp);
|
|
ENCODEZ(deltaS);
|
|
changes |= NEW_U;
|
|
} else if (th->th_urp != oth->th_urp) {
|
|
|
|
/*
|
|
* argh! URG not set but urp changed -- a sensible implementation should
|
|
* never do this but RFC793 doesn't prohibit the change so we have to
|
|
* deal with it.
|
|
*/
|
|
goto uncompressed;
|
|
}
|
|
deltaS = (u_short) (ntohs(th->th_win) - ntohs(oth->th_win));
|
|
if (deltaS) {
|
|
ENCODE(deltaS);
|
|
changes |= NEW_W;
|
|
}
|
|
deltaA = ntohl(th->th_ack) - ntohl(oth->th_ack);
|
|
if (deltaA) {
|
|
if (deltaA > 0xffff) {
|
|
goto uncompressed;
|
|
}
|
|
ENCODE(deltaA);
|
|
changes |= NEW_A;
|
|
}
|
|
deltaS = ntohl(th->th_seq) - ntohl(oth->th_seq);
|
|
if (deltaS) {
|
|
if (deltaS > 0xffff) {
|
|
goto uncompressed;
|
|
}
|
|
ENCODE(deltaS);
|
|
changes |= NEW_S;
|
|
}
|
|
switch (changes) {
|
|
|
|
case 0:
|
|
|
|
/*
|
|
* Nothing changed. If this packet contains data and the last one didn't,
|
|
* this is probably a data packet following an ack (normal on an
|
|
* interactive connection) and we send it compressed. Otherwise it's
|
|
* probably a retransmit, retransmitted ack or window probe. Send it
|
|
* uncompressed in case the other side missed the compressed version.
|
|
*/
|
|
if (ip->ip_len != cs->cs_ip.ip_len &&
|
|
ntohs(cs->cs_ip.ip_len) == hlen)
|
|
break;
|
|
|
|
/* (fall through) */
|
|
|
|
case SPECIAL_I:
|
|
case SPECIAL_D:
|
|
|
|
/*
|
|
* actual changes match one of our special case encodings -- send packet
|
|
* uncompressed.
|
|
*/
|
|
goto uncompressed;
|
|
|
|
case NEW_S | NEW_A:
|
|
if (deltaS == deltaA &&
|
|
deltaS == ntohs(cs->cs_ip.ip_len) - hlen) {
|
|
/* special case for echoed terminal traffic */
|
|
changes = SPECIAL_I;
|
|
cp = new_seq;
|
|
}
|
|
break;
|
|
|
|
case NEW_S:
|
|
if (deltaS == ntohs(cs->cs_ip.ip_len) - hlen) {
|
|
/* special case for data xfer */
|
|
changes = SPECIAL_D;
|
|
cp = new_seq;
|
|
}
|
|
break;
|
|
}
|
|
|
|
deltaS = ntohs(ip->ip_id) - ntohs(cs->cs_ip.ip_id);
|
|
if (deltaS != 1) {
|
|
ENCODEZ(deltaS);
|
|
changes |= NEW_I;
|
|
}
|
|
if (th->th_flags & TH_PUSH)
|
|
changes |= TCP_PUSH_BIT;
|
|
|
|
/*
|
|
* Grab the cksum before we overwrite it below. Then update our state with
|
|
* this packet's header.
|
|
*/
|
|
deltaA = ntohs(th->th_sum);
|
|
memcpy(&cs->cs_ip, ip, hlen);
|
|
|
|
/*
|
|
* We want to use the original packet as our compressed packet. (cp -
|
|
* new_seq) is the number of bytes we need for compressed sequence numbers.
|
|
* In addition we need one byte for the change mask, one for the connection
|
|
* id and two for the tcp checksum. So, (cp - new_seq) + 4 bytes of header
|
|
* are needed. hlen is how many bytes of the original packet to toss so
|
|
* subtract the two to get the new packet size.
|
|
*/
|
|
deltaS = cp - new_seq;
|
|
cp = (u_char *) ip;
|
|
|
|
/*
|
|
* Since fastq traffic can jump ahead of the background traffic, we don't
|
|
* know what order packets will go on the line. In this case, we always
|
|
* send a "new" connection id so the receiver state stays synchronized.
|
|
*/
|
|
if (comp->last_xmit == cs->cs_id && compress_cid) {
|
|
hlen -= deltaS + 3;
|
|
cp += hlen;
|
|
*cp++ = changes;
|
|
} else {
|
|
comp->last_xmit = cs->cs_id;
|
|
hlen -= deltaS + 4;
|
|
cp += hlen;
|
|
*cp++ = changes | NEW_C;
|
|
*cp++ = cs->cs_id;
|
|
}
|
|
m->m_len -= hlen;
|
|
m->m_offset += hlen;
|
|
*cp++ = deltaA >> 8;
|
|
*cp++ = deltaA;
|
|
memcpy(cp, new_seq, deltaS);
|
|
slstat->sls_compressed++;
|
|
return (TYPE_COMPRESSED_TCP);
|
|
|
|
/*
|
|
* Update connection state cs & send uncompressed packet ('uncompressed'
|
|
* means a regular ip/tcp packet but with the 'conversation id' we hope to
|
|
* use on future compressed packets in the protocol field).
|
|
*/
|
|
uncompressed:
|
|
memcpy(&cs->cs_ip, ip, hlen);
|
|
ip->ip_p = cs->cs_id;
|
|
comp->last_xmit = cs->cs_id;
|
|
return (TYPE_UNCOMPRESSED_TCP);
|
|
}
|
|
|
|
|
|
int
|
|
sl_uncompress_tcp(u_char ** bufp, int len, u_int type, struct slcompress *comp,
|
|
struct slstat *slstat, int max_state)
|
|
{
|
|
register u_char *cp;
|
|
register u_int hlen, changes;
|
|
register struct tcphdr *th;
|
|
register struct cstate *cs;
|
|
register struct ip *ip;
|
|
u_short *bp;
|
|
|
|
switch (type) {
|
|
|
|
case TYPE_UNCOMPRESSED_TCP:
|
|
ip = (struct ip *) * bufp;
|
|
if (ip->ip_p > max_state)
|
|
goto bad;
|
|
cs = &comp->rstate[comp->last_recv = ip->ip_p];
|
|
comp->flags &= ~SLF_TOSS;
|
|
ip->ip_p = IPPROTO_TCP;
|
|
|
|
/*
|
|
* Calculate the size of the TCP/IP header and make sure that we don't
|
|
* overflow the space we have available for it.
|
|
*/
|
|
hlen = ip->ip_hl << 2;
|
|
if (hlen + sizeof(struct tcphdr) > len)
|
|
goto bad;
|
|
th = (struct tcphdr *) & ((char *) ip)[hlen];
|
|
hlen += THOFFSET(th) << 2;
|
|
if (hlen > MAX_HDR)
|
|
goto bad;
|
|
memcpy(&cs->cs_ip, ip, hlen);
|
|
cs->cs_hlen = hlen;
|
|
slstat->sls_uncompressedin++;
|
|
return (len);
|
|
|
|
default:
|
|
goto bad;
|
|
|
|
case TYPE_COMPRESSED_TCP:
|
|
break;
|
|
}
|
|
|
|
/* We've got a compressed packet. */
|
|
slstat->sls_compressedin++;
|
|
cp = *bufp;
|
|
changes = *cp++;
|
|
log_Printf(LogDEBUG, "compressed: changes = %02x\n", changes);
|
|
|
|
if (changes & NEW_C) {
|
|
/*
|
|
* Make sure the state index is in range, then grab the state. If we have
|
|
* a good state index, clear the 'discard' flag.
|
|
*/
|
|
if (*cp > max_state || comp->last_recv == 255)
|
|
goto bad;
|
|
|
|
comp->flags &= ~SLF_TOSS;
|
|
comp->last_recv = *cp++;
|
|
} else {
|
|
/*
|
|
* this packet has an implicit state index. If we've had a line error
|
|
* since the last time we got an explicit state index, we have to toss
|
|
* the packet.
|
|
*/
|
|
if (comp->flags & SLF_TOSS) {
|
|
slstat->sls_tossed++;
|
|
return (0);
|
|
}
|
|
}
|
|
cs = &comp->rstate[comp->last_recv];
|
|
hlen = cs->cs_ip.ip_hl << 2;
|
|
th = (struct tcphdr *) & ((u_char *) & cs->cs_ip)[hlen];
|
|
th->th_sum = htons((*cp << 8) | cp[1]);
|
|
cp += 2;
|
|
if (changes & TCP_PUSH_BIT)
|
|
th->th_flags |= TH_PUSH;
|
|
else
|
|
th->th_flags &= ~TH_PUSH;
|
|
|
|
switch (changes & SPECIALS_MASK) {
|
|
case SPECIAL_I:
|
|
{
|
|
register u_int i = ntohs(cs->cs_ip.ip_len) - cs->cs_hlen;
|
|
|
|
th->th_ack = htonl(ntohl(th->th_ack) + i);
|
|
th->th_seq = htonl(ntohl(th->th_seq) + i);
|
|
}
|
|
break;
|
|
|
|
case SPECIAL_D:
|
|
th->th_seq = htonl(ntohl(th->th_seq) + ntohs(cs->cs_ip.ip_len)
|
|
- cs->cs_hlen);
|
|
break;
|
|
|
|
default:
|
|
if (changes & NEW_U) {
|
|
th->th_flags |= TH_URG;
|
|
DECODEU(th->th_urp)
|
|
} else
|
|
th->th_flags &= ~TH_URG;
|
|
if (changes & NEW_W)
|
|
DECODES(th->th_win)
|
|
if (changes & NEW_A)
|
|
DECODEL(th->th_ack)
|
|
if (changes & NEW_S) {
|
|
log_Printf(LogDEBUG, "NEW_S: %02x, %02x, %02x\n",
|
|
*cp, cp[1], cp[2]);
|
|
DECODEL(th->th_seq)
|
|
}
|
|
break;
|
|
}
|
|
if (changes & NEW_I) {
|
|
DECODES(cs->cs_ip.ip_id)
|
|
} else
|
|
cs->cs_ip.ip_id = htons(ntohs(cs->cs_ip.ip_id) + 1);
|
|
|
|
log_Printf(LogDEBUG, "Uncompress: id = %04x, seq = %08lx\n",
|
|
cs->cs_ip.ip_id, (u_long)ntohl(th->th_seq));
|
|
|
|
/*
|
|
* At this point, cp points to the first byte of data in the packet.
|
|
* Back up cp by the tcp/ip header length to make room for the
|
|
* reconstructed header (we assume the packet we were handed has enough
|
|
* space to prepend 128 bytes of header). Adjust the length to account
|
|
* for the new header & fill in the IP total length.
|
|
*/
|
|
len -= (cp - *bufp);
|
|
if (len < 0)
|
|
/*
|
|
* we must have dropped some characters (crc should detect this but the
|
|
* old slip framing won't)
|
|
*/
|
|
goto bad;
|
|
|
|
*bufp = cp - cs->cs_hlen;
|
|
len += cs->cs_hlen;
|
|
cs->cs_ip.ip_len = htons(len);
|
|
|
|
/* recompute the ip header checksum */
|
|
cs->cs_ip.ip_sum = 0;
|
|
bp = (u_short *)&cs->cs_ip;
|
|
for (changes = 0; hlen > 0; hlen -= 2)
|
|
changes += *bp++;
|
|
changes = (changes & 0xffff) + (changes >> 16);
|
|
changes = (changes & 0xffff) + (changes >> 16);
|
|
cs->cs_ip.ip_sum = ~changes;
|
|
|
|
/* And copy the result into our buffer */
|
|
memcpy(*bufp, &cs->cs_ip, cs->cs_hlen);
|
|
|
|
return (len);
|
|
bad:
|
|
comp->flags |= SLF_TOSS;
|
|
slstat->sls_errorin++;
|
|
return (0);
|
|
}
|
|
|
|
int
|
|
sl_Show(struct cmdargs const *arg)
|
|
{
|
|
prompt_Printf(arg->prompt, "VJ compression statistics:\n");
|
|
prompt_Printf(arg->prompt, " Out: %d (compress) / %d (total)",
|
|
arg->bundle->ncp.ipcp.vj.slstat.sls_compressed,
|
|
arg->bundle->ncp.ipcp.vj.slstat.sls_packets);
|
|
prompt_Printf(arg->prompt, " %d (miss) / %d (search)\n",
|
|
arg->bundle->ncp.ipcp.vj.slstat.sls_misses,
|
|
arg->bundle->ncp.ipcp.vj.slstat.sls_searches);
|
|
prompt_Printf(arg->prompt, " In: %d (compress), %d (uncompress)",
|
|
arg->bundle->ncp.ipcp.vj.slstat.sls_compressedin,
|
|
arg->bundle->ncp.ipcp.vj.slstat.sls_uncompressedin);
|
|
prompt_Printf(arg->prompt, " %d (error), %d (tossed)\n",
|
|
arg->bundle->ncp.ipcp.vj.slstat.sls_errorin,
|
|
arg->bundle->ncp.ipcp.vj.slstat.sls_tossed);
|
|
return 0;
|
|
}
|