Hi,
Not an expert in this field, but a quick look at the code reveiled this
interesting snippet:
/*
* this is the GSM 03.40 definition with the bit 2
* set to 1 for uplink messages
*/
static const value_string msg_type_strings[] = {
{ 0, "SMS-DELIVER" },
{ 4, "SMS-DELIVER REPORT" },
......
So it seems that bit 2 is used for direction determination.
This is set in this part of the code:
/*
* convert the 2 bit value to one based on direction
*/
if (pinfo->p2p_dir == P2P_DIR_UNKNOWN)
{
/* Return Result ... */
if (msg_type == 0) /* SMS-DELIVER */
{
msg_type |= 0x04; /* see the msg_type_strings */
}
}
else
{
msg_type |= ((pinfo->p2p_dir == P2P_DIR_RECV) ? 0x04 : 0x00);
}
Thanx,
Jaap
On Mon, 18 Dec 2006, joyce wrote:
> Hello All,
>
> Anyone know the tshark filter for gsm_map? The problem I met is: I generated
> a SMS mt-forwardSM MAP request, however from the pcap file, the "GSM SMS
> TPDU" part shows the type is "SMS-DELIVER REPORT" instead of "SMS-DELIVER".
>
> I have checked "3GPP TS 23.040 V6.8.0 (2006-09)" for realization of SMS, in
> the PDU type SMS-DELIVERY, the TP-MTI(TP-Message-Type-Indicator) is:
>
> bit1 bit0 Message type
>
> 0 0 SMS-DELIVER (in the direction SC to MS)
>
> 0 0 SMS-DELIVER REPORT (in the direction MS to SC)
>
> Therefore SMS-DELIVERY and SMS-DELIVER REPORT have the same TP-MTI but for
> different direction. Here the question is how tshark will know the
> direction? If it can not know the direction, how does tshark to
> differentiate the 2 types of TPDU?
>
>
>
> My operation environment:
>
> - OS: solaris 9/freebsd 6.1,the results are same on the 2 platform
>
> - Tshark version: 0.99.4
>
>
>
>
>
> Part of the decoded trace:
>
> GSM Mobile Application
>
> Component: invoke (1)
>
> invoke
>
> invokeID: 1
>
> opCode: localValue (0)
>
> localValue: mt-forwardSM (44)
>
> sm-RP-DA: imsi (0)
>
> imsi: 1122334455667788
>
> Imsi digits: 1122334455667788
>
> sm-RP-OA: msisdn (2)
>
> msisdn: 3938373731303135
>
> 0... .... = Extension: Extension
>
> .011 .... = Nature of number: Network Specific Number
> (0x03)
>
> .... 1001 = Number plan: Private Numbering (0x09)
>
> ISDN Address digits: 83737313031353
>
> sm-RP-UI: 240A9156792562404000000000000000000141
>
> moreMessagesToSend
>
> GSM SMS TPDU (GSM 03.40) SMS-DELIVER REPORT
>
> .0.. .... : TP-User-Data-Header-Indicator: The TP-UD field contains
> only the short message
>
> .... .1.. : TP-More-Messages-to-Send: No more messages are waiting for
> the MS in this SC
>
> .... ..00 : TP-Message-Type-Indicator
>
> TP-Parameter-Indicator
>
> 0... .... : No extension
>
> .000 1... : Reserved
>
> .... .0.. : TP-UDL not present
>
> .... ..1. : TP-DCS present
>
> .... ...0 : TP-PID not present
>
> TP-Data-Coding-Scheme (145)
>
> 1001 .... : Reserved coding groups
>
>
>
>
>
> Thanks.
>
>
>
> Joyce
>
>