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Note that a dissector heuristic test *must not* cause an exception before returning FALSE. 

Change-Id: I9f1ab000f7a2c554d1c20abf8ca4e4bab4b5ef27
Reviewed-on: https://code.wireshark.org/review/635
Reviewed-by: Bill Meier <wmeier@newsguy.com>
Tested-by: Bill Meier <wmeier@newsguy.com>
This commit is contained in:
Bill Meier 2014-03-11 10:28:41 -04:00
parent 36db2df1c1
commit 53dab8e1f1
1 changed files with 10 additions and 0 deletions
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doc/README.heuristic
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@ -91,6 +91,13 @@ Obviously, this is *not* 100% bullet proof, but it's the best WS can offer to
its users here - and improving the heuristic is always possible if it turns out
that it's not good enough to distinguish between two given protocols.
Note: The heuristic code in a dissector *must not* cause an exception
(before returning FALSE) as this will prevent following
heuristic dissector handoffs. In practce, this normally means
that a test should be done to verify that the required data is
available in the tvb before fetching from the tvb. (See the
example below).
Heuristic Code Example
----------------------
@ -120,6 +127,9 @@ static gboolean
dissect_PROTOABBREV_heur(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, void *data)
{
...
/* 0) Verify needed bytes available in tvb so tvb_get...() doesn't cause exception.
if (tvb_length(tvb) < 5)
return FALSE;
/* 1) first byte must be 0x42 */
if ( tvb_get_guint8(tvb, 0) != 0x42 )