Date: Thu, 29 Feb 1996 20:13:28 -0500 (EST) From: Richard Toren <rpt@miles.sso.loral.com> To: Lyndon Nerenberg VE7TCP <lyndon@orthanc.com> Cc: hackers@freebsd.org Subject: Re: tcpdump changes Message-ID: <Pine.SUN.3.91.960229200656.15478A-100000@miles> In-Reply-To: <199602290146.RAA05053@multivac.orthanc.com>
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On Wed, 28 Feb 1996, Lyndon Nerenberg VE7TCP wrote:
> I'm thinking of making a change to tcpdump and would like
> to solicit comments ...
>
> The '-x' option prints a hex dump of packet contents (modulo capture
> length). I would like to modify it to also include an ASCII
> representation of the same data. (Makes it easier to trace things like
I did that with the following modification to tcpdump.c. This routine is
near the end of the source file. This was 3.0.2 source. I don't have the
original handy, but this should be a good start. Then rebuild and the -x
will dump hex/ascii.
Have fun...
default_print(register const u_char *data, register int len)
{
/* DESCZ
Dumps to dbglog file a hex/ascii formatted dump of the
passed address for the specified number of bytes.
*/
char hexbuf[64];
char chrbuf[24];
char *k;
int i, j;
if (len <= 0) return;
printf("\n");
for (i=j=0, k=hexbuf; i< len; i++, j++)
{
if (j >= 16)
{
chrbuf[j] = 0x00;
printf ("\t\t\t|%-42s|%-16s|\n", hexbuf, chrbuf);
j = 0;
k = hexbuf;
}
if (j&1)
{
sprintf (k, "%02X ", data[i]);
chrbuf[j] = isprint (data[i]) ? data[i] : '.';
k = k+3;
}
else
{
sprintf (k, "%02X", data[i]);
chrbuf[j] = isprint (data[i]) ? data[i] : '.';
k = k+2;
}
}
if (j > 0)
{
chrbuf[j] = 0x00;
printf( "\t\t\t|%-42s|%-16s|\n", hexbuf, chrbuf);
j = 0;
k = hexbuf;
}
fflush (stdout);
/********** original *****
register const u_short *sp;
register u_int i;
register int nshorts;
if ((int)bp & 1) {
default_print_unaligned(bp, length);
return;
}
sp = (u_short *)bp;
nshorts = (u_int) length / sizeof(u_short);
i = 0;
while (--nshorts >= 0) {
if ((i++ % 8) == 0)
(void)printf("\n\t\t\t");
(void)printf(" %04x", ntohs(*sp++));
}
if (length & 1) {
if ((i % 8) == 0)
(void)printf("\n\t\t\t");
(void)printf(" %02x", *(u_char *)sp);
}
*********/
}
====================================================
Rip Toren | The bad news is that C++ is not an object-oriented |
rpt@miles.sso.loral.com | programming language. .... The good news is that |
| C++ supports object-oriented programming. |
| C++ Programming & Fundamental Concepts |
| by Anderson & Heinze |
====================================================
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