Hi,
which libss7 version are you looked into, I'm using mine and have tons
of incomming calls with SAM.
regards,
Attila
On Tue, 2009-10-20 at 20:32 +0800, Tian wrote:
> Hi guys,
>
> I am reading libss7 source code and I think I've found a bug in it,
> following is my description of the bug and my tentative fix to the bug, as I
> don't have a running Asterisk box, I hope you will kindly help me check it,
> thanks!
>
> According to ITU-T Recommendation Q.763, section 1.6 'Mandatory variable
> part':
>
> "A pointer is also included to indicate the beginning of the optional part.
> If the message type indicates that no optional part is allowed, then this
> pointer will not be present. If the message type indicates that an optional
> part is possible, but there is no optional part included in this particular
> message, then a pointer field containing all zeros will be used."
>
> Thus, ISUP messages that don't carry any optionals fall into two categories:
> 1) those include a 'Pointer to start of optional part' containing all zeros
> (e.g., SAM falls into this category) and 2) those don't include a 'Pointer
> to start of optional part'.
>
> libss7 can only correctly construct ISUP messages carrying zero optional
> parameters that fall into category 2) if messages that fall into category 1)
> are to be constructed, libss7 will fail.
>
> The bug shows up in the file isup.c (Libss7 trunk revison 272, lines
> 2425-2432), my fix to this bug specifically for SAM is as follows (you may
> adopt the fix by replacing everyting between the fisrt and the last two
> comment lines):
>
> /* Make sure we grab our opional parameters */
> if (optparams || (messagetype == ISUP_SAM)) {
> if (optparams)
> opt_ptr = &mh->data[offset + varparams];
> /* a SAM message doesn't have any optionals,
> * but the 'Pointer to start of optional part' is still present
> */
> offset += varparams + 1; /* add one for the optionals */
> len -= varparams + 1;
> } else {
> offset += varparams;
> len -= varparams;
> }
>
> /* Whew, some complicated math for all of these offsets and different
> sections */
>
>
>
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