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Date:      Fri, 11 Aug 1995 15:23:46 -0400 (EDT)
From:      Robin Cutshaw <robin@intercore.com>
To:        current@freebsd.org
Subject:   speaking of tcpdump
Message-ID:  <199508111923.PAA25640@intercore.com>
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Which reminds me...

I use tcpdump pretty extensively as a network tool and wanted to see
both ascii and hex for full packet dumps (and I know about the -D
option on some versions).  Here's a patch that will give the network
problem solver a much better look at what's going on (IMHO).  Turn
it on by using "-x -x" on the command line (kinda hidden, huh?).

I'm not advocating that this should be included in the default tcpdump
(especially with the security rammifications) but I thought the
developers here might find it useful.

robin

*** tcpdump.c.ORIG	Sat Jul 22 17:45:55 1995
--- tcpdump.c	Sat Jul 22 17:47:00 1995
***************
*** 351,401 ****
  	exit(0);
  }
  
- /* Like default_print() but data need not be aligned */
  void
! default_print_unaligned(register const u_char *cp, register int length)
  {
! 	register u_int i, s;
! 	register int nshorts;
! 
! 	nshorts = (u_int) length / sizeof(u_short);
! 	i = 0;
! 	while (--nshorts >= 0) {
! 		if ((i++ % 8) == 0)
! 			(void)printf("\n\t\t\t");
! 		s = *cp++;
! 		(void)printf(" %02x%02x", s, *cp++);
! 	}
! 	if (length & 1) {
! 		if ((i % 8) == 0)
! 			(void)printf("\n\t\t\t");
! 		(void)printf(" %02x", *cp);
! 	}
  }
  
  void
  default_print(register const u_char *bp, register int length)
  {
- 	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);
  	}
  }
  
--- 351,400 ----
  	exit(0);
  }
  
  void
! default_print_unaligned(register const u_char *bp, register int length)
  {
! 	default_print(bp, length);
  }
  
  void
  default_print(register const u_char *bp, register int length)
  {
  	register u_int i;
! 	register u_char *xbufp, *abufp, *cp, c;
! 	u_char xbuf[16*3+1], abuf[16+1];
  
  	i = 0;
! 	xbufp = xbuf;
! 	abufp = abuf;
! 	cp = bp;
! 	while (i < length) {
! 		c = *cp >> 4;
! 		*xbufp++ = (c > 9) ? ((c-10)+'a') : (c+'0');
! 		c = *cp & (u_char )0x0f;
! 		*xbufp++ = (c > 9) ? ((c-10)+'a') : (c+'0');
! 		*xbufp++ = ' ';
! 		c = *cp++;
! 		*abufp++ = isprint(c) ? c : '.';
! 		i++;
! 		if ((i != 1) && ((i % 16) == 0)) {
! 			*xbufp++ = '\0';
! 			*abufp++ = '\0';
! 			if (xflag > 1)
! 				(void)printf("\n\t%-48s    |%-16s|", xbuf, abuf);
! 			else
! 				(void)printf("\n\t%-48s", xbuf);
! 			xbufp = xbuf;
! 			abufp = abuf;
! 		}
  	}
! 	if ((i % 16) != 0) {
! 		*xbufp++ = '\0';
! 		*abufp++ = '\0';
! 		if (xflag > 1)
! 			(void)printf("\n\t%-48s    |%-16s|", xbuf, abuf);
! 		else
! 			(void)printf("\n\t%-48s", xbuf);
  	}
  }

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