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Add remove_last_data_source and fix bug 9169 

The OP asked 9169 to be reopened because the capture was spewing ~40GB of output
when dissected with tshark. Investigation showed this was because the HTTP
dissector was requesting ONE_MORE_PACKET reassembly a lot, and TCP was adding
each step as a data-source which was being printed by tshark's hex dump. This
was leading to O(n^2) of output.

To fix, introduce function remove_last_data_source which removes the most recent
data source from the list. If the subdissector in TCP reassembly asks for
ONE_MORE_PACKET, assume it hasn't added any tree items (since it shouldn't have)
and remove the data source since it is unnecessary.

This may break dissectors which add tree items and *then* return
ONE_MORE_PACKET, since they will have their data source removed out from under
them. I believe those cases should be fixed to not add tree items until they're
sure they have enough data.

Change-Id: Iff07f959b8b8bd1acda9bff03f7c8684901ba8aa
Reviewed-on: https://code.wireshark.org/review/38
Reviewed-by: Evan Huus <eapache@gmail.com>
Tested-by: Evan Huus <eapache@gmail.com>
This commit is contained in:
Evan Huus 2014-01-29 18:04:20 -05:00
parent 458b835683
commit 21e0a63b29
3 changed files with 18 additions and 0 deletions
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1
epan/dissectors/packet-tcp.c
View File

@ -1889,6 +1889,7 @@ again:
* being a new higher-level PDU that also
* needs desegmentation).
*/
remove_last_data_source(pinfo);
fragment_set_partial_reassembly(&tcp_reassembly_table,
pinfo, msp->first_frame, NULL);

15
epan/packet.c
View File

@ -324,9 +324,24 @@ add_new_data_source(packet_info *pinfo, tvbuff_t *tvb, const char *name)
src = g_slice_new(struct data_source);
src->tvb = tvb;
src->name = g_strdup(name);
/* This could end up slow, but we should never have that many data
* sources so it probably doesn't matter */
pinfo->data_src = g_slist_append(pinfo->data_src, src);
}
void
remove_last_data_source(packet_info *pinfo)
{
struct data_source *src;
GSList *last;
last = g_slist_last(pinfo->data_src);
src = (struct data_source *)last->data;
pinfo->data_src = g_slist_delete_link(pinfo->data_src, last);
g_free(src->name);
g_slice_free(struct data_source, src);
}
const char*
get_data_source_name(const struct data_source *src)
{

2
epan/packet.h
View File

@ -512,6 +512,8 @@ final_registration_all_protocols(void);
*/
WS_DLL_PUBLIC void add_new_data_source(packet_info *pinfo, tvbuff_t *tvb,
const char *name);
/* Removes the last-added data source, if it turns out it wasn't needed */
WS_DLL_PUBLIC void remove_last_data_source(packet_info *pinfo);
/*