Date: Thu, 19 Oct 2000 23:43:33 -0500 (CDT) From: Matthew Cerha <mcerha@mcerha-dsl2.cisco.com> To: FreeBSD-gnats-submit@freebsd.org Subject: bin/22138: tcpdump not handling Message-ID: <200010200443.e9K4hXk58824@mcerha-dsl2.cisco.com>
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>Number: 22138
>Category: bin
>Synopsis: tcpdump not handling -v option correctly
>Confidential: yes
>Severity: non-critical
>Priority: low
>Responsible: freebsd-bugs
>State: open
>Quarter:
>Keywords:
>Date-Required:
>Class: sw-bug
>Submitter-Id: current-users
>Arrival-Date: Thu Oct 19 21:50:01 PDT 2000
>Closed-Date:
>Last-Modified:
>Originator: Matthew Cerha
>Release: FreeBSD 4.1-STABLE i386
>Organization:
CharlieFox Consulting
>Environment:
FreeBSD mcerha-dsl2.cisco.com 4.1-STABLE FreeBSD 4.1-STABLE #0: Thu Sep 21 22:24:06 CDT 2000 mcerha@super.freak.net:/usr/obj/cvs/FreeBSD/4.x/src/sys/SMP i386
>Description:
It appears that tcpdump does not properly interpret the -v (verbose) option
for TCP packet decodes. There appears to be a flaw in the flow control.
In src/contrib/tcpdump/print-tcp.c:
497 if (!qflag && vflag && length > 0
498 && (sport == TELNET_PORT || dport == TELNET_PORT))
499 telnet_print(bp, length);
500 else if (sport == BGP_PORT || dport == BGP_PORT)
501 bgp_print(bp, length);
502 else if (sport == NETBIOS_SSN_PORT || dport == NETBIOS_SSN_PORT) 503 nbt_tcp_print(bp, length);
504 return;
The first section doesn't make sense. The sport and dport clauses should be
grouped together and not with the flag clause.
PS Jerry found this bug. I'm just trying to report it :)
>How-To-Repeat:
Just run tcpdump -v.
>Fix:
Apply the diff to src/contrib/tcpdump/print-tcp.c.
497,498c497,498
A
< if (!qflag && vflag && length > 0) {
< if (sport == TELNET_PORT || dport == TELNET_PORT)
---
> if (!qflag && vflag && length > 0
> && (sport == TELNET_PORT || dport == TELNET_PORT))
504d503
< }
>Release-Note:
>Audit-Trail:
>Unformatted:
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