Michael Geisberger wrote:
With text format this works fine,
tethereal -T text -l -n -r\test\input -R "(gtp.message==0x10) and
(frame.time)" -z proto,colinfo,ip,frame.time >>output
but when I change the -T text to -T pdml, I get this segmentation error.
The same thing happens if you replace it with "-V".
The problem is that, if we're not generating the columns - which we
don't do in verbose mode ("-V") and which we don't do if we're
generating PDML - taps such as the "proto,colinfo" tap that modify the
columns won't work.
We'd need to have a way for a tap to specify that it requires that the
columns be generated.
Note, however, that
tethereal -T pdml -l -n -r\test\input -R "(gtp.message==0x10) and
(frame.time)" -z proto,colinfo,ip,frame.time >>output
probably wouldn't do what you want - the "proto,colinfo" tap modifies
the columns in non-verbose text mode, it has *NO* effect whatsoever on
XML output, so if you want to "filter certain values and save them in
XML format", that won't do it.
There's no mechanism in Ethereal to selectively write out, in XML
format, only selected fields of a packet.
Perhaps we should, instead, have a way for a tap to ask whether the
columns will be generated and written, and have the "proto,colinfo" tap
report an error and exit if the user hasn't requested that the columns
be generated, as the "colinfo" part of "proto,colinfo" indicates that
the tap modifies the columns and is thus useless if the columns aren't
being written.
If somebody wants a way to have selected fields written out in PDML
format (rather than actually writing out PDML, which is specified:
http://analyzer.polito.it/30alpha/docs/dissectors/PDMLSpec.htm
to contain "all the most important information related to the protocols
and the fields that are contained into the packet (e.g. the protocols,
all the field names and their values, and more)."), that might be a
useful option - but it's not "-z proto,colinfo", which is intended for
other purposes. It might well be a useful replacement for many (most?
all?) uses of "-z proto,colinfo", but that's another matter.
