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Fix bugs in the ISO (Fletcher) checksum, obey the -q flag, misc cleanup of

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ISO based code, and document new options (courtesy of libpcap).
Submitted by:	Tony Li <tli@jnx.com>
This commit is contained in:
Paul Traina 1996-08-21 20:03:57 +00:00
parent 0d086d2934
commit 12e9609024
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=17751
2 changed files with 29 additions and 30 deletions
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45
contrib/tcpdump/print-isoclns.c
View File

@ -53,7 +53,7 @@ struct rtentry;
#define NLPID_ISIS 131 /* 0x83 */
#define NLPID_NULLNS 0
static int osi_cksum(const u_char *, u_int, const u_char *, u_char *, u_char *);
static int osi_cksum(const u_char *, int, u_char *);
static void esis_print(const u_char *, u_int);
static int isis_print(const u_char *, u_int);
@ -73,7 +73,6 @@ isoclns_print(const u_char *p, u_int length, u_int caplen,
switch (*p) {
case NLPID_CLNS:
/* esis_print(&p, &length); */
printf("iso clns");
if (!eflag)
(void)printf(" %s > %s",
@ -97,9 +96,8 @@ isoclns_print(const u_char *p, u_int length, u_int caplen,
etheraddr_string(esrc),
etheraddr_string(edst));
(void)printf(" len=%d ", length);
if (!isis_print(p, length)) {
if (!isis_print(p, length))
default_print_unaligned(p, caplen);
}
break;
case NLPID_NULLNS:
@ -189,9 +187,10 @@ esis_print(const u_char *p, u_int length)
}
off[0] = eh->cksum[0];
off[1] = eh->cksum[1];
if (vflag && osi_cksum(p, li, eh->cksum, cksum, off)) {
printf(" bad cksum (got %02x%02x want %02x%02x)",
eh->cksum[1], eh->cksum[0], cksum[1], cksum[0]);
if (vflag && osi_cksum(p, li, off)) {
printf(" bad cksum (got %02x%02x)",
eh->cksum[1], eh->cksum[0]);
default_print(p, length);
return;
}
if (eh->version != 1) {
@ -239,7 +238,8 @@ esis_print(const u_char *p, u_int length)
}
if (p > snapend)
return;
printf("\n\t\t\t %s", isonsap_string(is));
if (!qflag)
printf("\n\t\t\t %s", isonsap_string(is));
li = ep - p;
break;
}
@ -537,36 +537,23 @@ isis_print (const u_char *p, u_int length)
return(1);
}
/*
* Verify the checksum. See 8473-1, Appendix C, section C.4.
*/
static int
osi_cksum(register const u_char *p, register u_int len,
const u_char *toff, u_char *cksum, u_char *off)
osi_cksum(register const u_char *p, register int len, u_char *off)
{
int x, y, f = (len - ((toff - p) + 1));
int32_t c0 = 0, c1 = 0;
if ((cksum[0] = off[0]) == 0 && (cksum[1] = off[1]) == 0)
if ((off[0] == 0) && (off[1] == 0))
return 0;
off[0] = off[1] = 0;
while (--len >= 0) {
c0 += *p++;
c1 += c0;
c0 %= 255;
c1 += c0;
c1 %= 255;
}
x = (c0 * f - c1);
if (x < 0)
x = 255 - (-x % 255);
else
x %= 255;
y = -1 * (x + c0);
if (y < 0)
y = 255 - (-y % 255);
else
y %= 255;
off[0] = x;
off[1] = y;
return (off[0] != cksum[0] || off[1] != cksum[1]);
return (c0 | c1);
}

14
contrib/tcpdump/tcpdump.1
View File

@ -265,6 +265,9 @@ protos are:
.BR sca ,
.BR moprc ,
.BR mopdl ,
.BR iso ,
.BR esis ,
.BR isis ,
.B tcp
and
.BR udp .
@ -445,7 +448,7 @@ True if the DECNET destination address is
.IP "\fBdecnet host \fIhost\fR"
True if either the DECNET source or destination address is
.IR host .
.IP "\fBip\fR, \fBarp\fR, \fBrarp\fR, \fBdecnet\fR"
.IP "\fBip\fR, \fBarp\fR, \fBrarp\fR, \fBdecnet\fR, \fBiso\fR"
Abbreviations for:
.in +.5i
.nf
@ -471,6 +474,15 @@ Abbreviations for:
.fi
.in -.5i
where \fIp\fR is one of the above protocols.
.IP "\fBesis\fR, \fBisis\fR"
Abbreviations for:
.in +.5i
.nf
\fBiso proto \fIp\fR
.fi
.in -.5i
where \fIp\fR is one of the above protocols.
Note that \fItcpdump\fR does an incomplete job of parsing these protocols.
.IP "\fIexpr relop expr\fR"
True if the relation holds, where \fIrelop\fR is one of >, <, >=, <=, =, !=,
and \fIexpr\fR is an arithmetic expression composed of integer constants