d/freebsd-dev
1
0
Fork 0
Code Issues Pull Requests Packages Projects Releases Wiki Activity

slcompress: split one of the functions into two parts, to allow use by both

Browse Source 
if_sl and if_ppp (from ppp-2.2), eliminating the nearly identical
 pppcompress.[ch] code.  Add maximum VJ compression states argument to
 sl_compress_init().
if_sl: call sl_compress_init() with the extra argument.
This commit is contained in:
Peter Wemm 1995-10-31 19:22:32 +00:00
parent 06cc185852
commit 71b9cf739a
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=11964
3 changed files with 88 additions and 38 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

4
sys/net/if_sl.c
View File

@ -31,7 +31,7 @@
* SUCH DAMAGE.
*
* @(#)if_sl.c 8.6 (Berkeley) 2/1/94
* $Id: if_sl.c,v 1.31 1995/09/10 12:22:59 bde Exp $
* $Id: if_sl.c,v 1.32 1995/09/17 23:38:29 ache Exp $
*/
/*
@ -243,7 +243,7 @@ slinit(sc)
}
sc->sc_buf = sc->sc_ep - SLRMAX;
sc->sc_mp = sc->sc_buf;
sl_compress_init(&sc->sc_comp);
sl_compress_init(&sc->sc_comp, -1);
return (1);
}

114
sys/net/slcompress.c
View File

@ -31,7 +31,7 @@
* SUCH DAMAGE.
*
* @(#)slcompress.c 8.2 (Berkeley) 4/16/94
* $Id: slcompress.c,v 1.4 1994/10/08 22:38:27 phk Exp $
* $Id: slcompress.c,v 1.5 1995/05/30 08:08:33 rgrimes Exp $
*/
/*
@ -67,18 +67,21 @@
#endif
void
sl_compress_init(comp)
sl_compress_init(comp, max_state)
struct slcompress *comp;
int max_state;
{
register u_int i;
register struct cstate *tstate = comp->tstate;
if (max_state == -1)
max_state = MAX_STATES - 1;
bzero((char *)comp, sizeof(*comp));
for (i = MAX_STATES - 1; i > 0; --i) {
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_STATES - 1];
tstate[0].cs_next = &tstate[max_state];
tstate[0].cs_id = 0;
comp->last_cs = &tstate[0];
comp->last_recv = 255;
@ -400,17 +403,69 @@ sl_uncompress_tcp(bufp, len, type, comp)
int len;
u_int type;
struct slcompress *comp;
{
u_char *hdr, *cp;
int hlen, vjlen;
cp = bufp? *bufp: NULL;
vjlen = sl_uncompress_tcp_core(cp, len, len, type, comp, &hdr, &hlen);
if (vjlen < 0)
return (0); /* error */
if (vjlen == 0)
return (len); /* was uncompressed already */
cp += vjlen;
len -= vjlen;
/*
* At this point, cp points to the first byte of data in the
* packet. If we're not aligned on a 4-byte boundary, copy the
* data down so the ip & tcp headers will be aligned. Then 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).
*/
if ((int)cp & 3) {
if (len > 0)
(void) ovbcopy(cp, (caddr_t)((int)cp &~ 3), len);
cp = (u_char *)((int)cp &~ 3);
}
cp -= hlen;
len += hlen;
BCOPY(hdr, cp, hlen);
*bufp = cp;
return (len);
}
/*
* Uncompress a packet of total length total_len. The first buflen
* bytes are at buf; this must include the entire (compressed or
* uncompressed) TCP/IP header. This procedure returns the length
* of the VJ header, with a pointer to the uncompressed IP header
* in *hdrp and its length in *hlenp.
*/
int
sl_uncompress_tcp_core(buf, buflen, total_len, type, comp, hdrp, hlenp)
u_char *buf;
int buflen, total_len;
u_int type;
struct slcompress *comp;
u_char **hdrp;
u_int *hlenp;
{
register u_char *cp;
register u_int hlen, changes;
register struct tcphdr *th;
register struct cstate *cs;
register struct ip *ip;
register u_short *bp;
register u_int vjlen;
switch (type) {
case TYPE_UNCOMPRESSED_TCP:
ip = (struct ip *) *bufp;
ip = (struct ip *) buf;
if (ip->ip_p >= MAX_STATES)
goto bad;
cs = &comp->rstate[comp->last_recv = ip->ip_p];
@ -420,10 +475,11 @@ sl_uncompress_tcp(bufp, len, type, comp)
hlen += ((struct tcphdr *)&((int *)ip)[hlen])->th_off;
hlen <<= 2;
BCOPY(ip, &cs->cs_ip, hlen);
cs->cs_ip.ip_sum = 0;
cs->cs_hlen = hlen;
INCR(sls_uncompressedin)
return (len);
*hdrp = (u_char *) &cs->cs_ip;
*hlenp = hlen;
return (0);
default:
goto bad;
@ -433,7 +489,7 @@ sl_uncompress_tcp(bufp, len, type, comp)
}
/* We've got a compressed packet. */
INCR(sls_compressedin)
cp = *bufp;
cp = buf;
changes = *cp++;
if (changes & NEW_C) {
/* Make sure the state index is in range, then grab the state.
@ -449,7 +505,7 @@ sl_uncompress_tcp(bufp, len, type, comp)
* explicit state index, we have to toss the packet. */
if (comp->flags & SLF_TOSS) {
INCR(sls_tossed)
return (0);
return (-1);
}
}
cs = &comp->rstate[comp->last_recv];
@ -497,42 +553,34 @@ sl_uncompress_tcp(bufp, len, type, comp)
/*
* At this point, cp points to the first byte of data in the
* packet. If we're not aligned on a 4-byte boundary, copy the
* data down so the ip & tcp headers will be aligned. Then 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.
* packet. Fill in the IP total length and update the IP
* header checksum.
*/
len -= (cp - *bufp);
if (len < 0)
vjlen = cp - buf;
buflen -= vjlen;
if (buflen < 0)
/* we must have dropped some characters (crc should detect
* this but the old slip framing won't) */
goto bad;
if ((int)cp & 3) {
if (len > 0)
(void) ovbcopy(cp, (caddr_t)((int)cp &~ 3), len);
cp = (u_char *)((int)cp &~ 3);
}
cp -= cs->cs_hlen;
len += cs->cs_hlen;
cs->cs_ip.ip_len = htons(len);
BCOPY(&cs->cs_ip, cp, cs->cs_hlen);
*bufp = cp;
total_len += cs->cs_hlen - vjlen;
cs->cs_ip.ip_len = htons(total_len);
/* recompute the ip header checksum */
{
register u_short *bp = (u_short *)cp;
bp = (u_short *) &cs->cs_ip;
cs->cs_ip.ip_sum = 0;
for (changes = 0; hlen > 0; hlen -= 2)
changes += *bp++;
changes = (changes & 0xffff) + (changes >> 16);
changes = (changes & 0xffff) + (changes >> 16);
((struct ip *)cp)->ip_sum = ~ changes;
}
return (len);
cs->cs_ip.ip_sum = ~ changes;
*hdrp = (u_char *) &cs->cs_ip;
*hlenp = cs->cs_hlen;
return vjlen;
bad:
comp->flags |= SLF_TOSS;
INCR(sls_errorin)
return (0);
return (-1);
}

8
sys/net/slcompress.h
View File

@ -35,7 +35,7 @@
*
* Van Jacobson (van@helios.ee.lbl.gov), Dec 31, 1989:
* - Initial distribution.
* $Id: slcompress.h,v 1.5 1994/08/22 14:16:36 bde Exp $
* $Id: slcompress.h,v 1.6 1995/05/30 08:08:34 rgrimes Exp $
*/
#ifndef _NET_SLCOMPRESS_H_
@ -153,9 +153,11 @@ struct slcompress {
/* flag values */
#define SLF_TOSS 1 /* tossing rcvd frames because of input err */
void sl_compress_init __P((struct slcompress *));
void sl_compress_init __P((struct slcompress *, int));
u_int sl_compress_tcp __P((struct mbuf *,
struct ip *, struct slcompress *, int));
int sl_uncompress_tcp __P((u_char **, int, u_int, struct slcompress *));
int sl_uncompress_tcp_core __P((u_char *, int, int, u_int,
struct slcompress *, u_char **, u_int *));
#endif /* !_NET_SLCOMPRESS_H_ */
#endif /* _NET_SLCOMPRESS_H_ */