https://bugs.wireshark.org/bugzilla/show_bug.cgi?id=5095
Bill Meier <wmeier@xxxxxxxxxxx> changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|ASSIGNED |RESOLVED
Resolution| |FIXED
--- Comment #18 from Bill Meier <wmeier@xxxxxxxxxxx> 2010-10-18 13:15:06 EDT ---
Ok: I've committed the dissector (with some additional changes from me)
in SVN #34558.
It would be much appreciated if you could add a page for the
ETCH protocol to the Wireshark Wiki (wiki.wireshark.org).
See: http://wiki.wireshark.org/HowToEdit
and http://wiki.wireshark.org/ProtocolReference
Thanks for your contribution !
--------------------
The main changes I made:
1. Fix a bug in add_symbol which caused intermittent Wireshark crashes.
Specifically:
gchar* tmp_val = (gchar *) g_malloc(strlen(symbol) + 1);
...
g_snprintf(tmp_val, ETCH_MAX_SYMBOL_LENGTH, "%s", symbol);
caused problems because ETCH_MAX_SYMBOL_LENGTH was larger than
the size of the allocated buffer.
It seems that g_snprintf requires that the provided buffer be of the
length specified even if it is known/guaranteed that strlen(symbol)
is less that length. Apparently g_snprintf writes to (initializes ?)
(some part of ?) the complete buffer.
So: the g_snprintf above was trashing memory beyond the space
allocated and thus eventually a crash sometimes occurred.
I fixed the bug by simplifying the code and by using
g_strdup_printf(...).
2. The tvb_length checks you so carefully added in the latest patch aren't
really needed. If dissector code attempts to access data beyond the end of
that contained in a frame (ie: a tvbuff), Wireshark will gracefully
handle that by generating an exception and displaying a "Malformed" message
(or something similar).
So: I removed the checks. :)
3. I tightened up the error checking done when reading the symbol hash file.
4. Although I originally suggested the use of report_open_failure(), I
decided to make a change to use report_failure() showing the error
message returned from ws_dir_open().
In addition to the above, I did some additional relatively minor cleanup.
-- On a different mote:
Originally I wasn't comfortable with the code related to:
/* Switch to another frame? => Clear column */
After doing some testing with the "multipacket" capture you provided (and with
another that I generated) I've convinced myself that the code is OK.
I'll attach another "multipacket" capture file with a frame containing a full
PDU as well as a partial PDU.
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