Dear Ethereal-developers,
Attached is a patch that fixes several decoding problem is the gsm_a
dissector. The bugs are also submitted to bugzilla id #684 and #687.
The problems are
1. Incorrect decoding of several fields in the Mobile Station Classmark 2 IE
in packet-gsm.c
I have found incorrect decoding of several fields in the Mobile Classmark 2
IE in GSM_A due to wrong bit masks being used
"ES IND" shares one bit with "Revision Level"
"A5/1 support" is bit 4, not bit 5.
"CM3" is bit 8 in octet three, not bit 1 in octet two.
"LCS VA" is bit 6, not bit 8.
The fields for "A5/2" and "A5/3" support has their values swapped around.
"0" means "not supported" and "1" means supported.
2. Incorrect decoding of Additional Access Technologies in IE MS Radio
Access Capability in packet-gsm_a.c
If the field "Additional Access Technologies" contains multiple additional
access technologies, the decoding is incorrect. There is a presence flag
missing in the decoding.
Log showing the incorrect decoding
MS Radio Access Capability
Length: 11
MS RA capability 1
Access Technology Type: (1) GSM E --note that GSM E covers GSM P
Length: 0x2a bits (42)
RF Power Capability, GMSK Power Class: (4) 2 W (33 dBm)
A5 Bits: (1) A5 bits follows
A5/1: (1) encryption algorithm available
<... not required information removed ...>
CDMA 2000 Radio Access Technology Capability: (0) CDMA 2000 not
supported
MS RA capability 2
Access Technology Type: (15) Indicates the presence of a list of
Additional access technologies
Length: 0x15 bits (21)
Access Technology Type: (11) unknown
RF Power Capability, GMSK Power Class: (6) Not specified??
8PSK Power Class: (0) 8PSK modulation not supported for uplink
with the supplied patch the decoding is successful
MS Radio Access Capability
Length: 11
MS RA capability 1
Access Technology Type: (1) GSM E --note that GSM E covers GSM P
Length: 0x2a bits (42)
RF Power Capability, GMSK Power Class: (4) 2 W (33 dBm)
A5 Bits: (1) A5 bits follows
A5/1: (1) encryption algorithm available
<... not required information removed ...>
CDMA 2000 Radio Access Technology Capability: (0) CDMA 2000 not
supported
MS RA capability 2
Access Technology Type: (15) Indicates the presence of a list of
Additional access technologies
Length: 0x15 bits (21)
Presence: (1) Present
Access Technology Type: (7) GSM 850
RF Power Capability, GMSK Power Class: (4) 2 W (33 dBm)
8PSK Power Class: (0) 8PSK modulation not supported for uplink
Presence: (1) Present
Access Technology Type: (3) GSM 1800
RF Power Capability, GMSK Power Class: (1) 1 W (30 dBm)
8PSK Power Class: (0) 8PSK modulation not supported for uplink
Presence: (0) Not Present
Regards,
Patrik
--
Patrik Olsson
TTPCom Ltd
Attachment:
packet_gsm_a.diff
Description: Binary data
