osmocom-net-gprs February 2013

osmocom-net-gprs@lists.osmocom.org

4 participants
3 discussions

problems with dissecting
by jolly 02 Mar '13

02 Mar '13

hi, steve and me experienced a problem with dissecting a "packet resource request" at pcu. the patch i attached will show the following output: $ make && src/osmo-pcu PayloadType = 1 | spare = 0 | R = 0 | MESSAGE_TYPE = 5 | Exist_ACCESS_TYPE = 1 | ACCESS_TYPE = 3 | : ID | Choice PacketResourceRequestID = 1 | u.TLLI = 0x7ee0e8fd | : End ID | Exist_MS_Radio_Access_capability = 1 | : MS_Radio_Access_capability | MS_RA_capability_value { | Choice MS_RA_capability_value_Choice = 1 | u.Content length = 34 | RF_Power_Capability = 4 | Exist_A5_bits = 1 | A5_bits = 96 | ES_IND = 1 | PS = 0 | VGCS = 0 | VBS = 0 | Exist_Multislot_capability = 1 | : Multislot_capability | Exist_HSCSD_multislot_class = 0 | Exist_GPRS_multislot_class = 1 | GPRS_multislot_class = 10 .... this is all correct, but then i patched the get_ms_class_by_capability() function at grps_rlcmac_data.c: ... printf("we have = %d\n", cap->Count_MS_RA_capability_value); for (i = 0; i < cap->Count_MS_RA_capability_value; i++) { printf("index=%d\n", cap->MS_RA_capability_value[i].IndexOfAccTech); printf("exists multislot capability %d\n", cap->MS_RA_capability_value[i].u.Content.Exist_Multislot_capability); printf("exists class %d\n", cap->MS_RA_capability_value[i].u.Content.Multislot_capability.Exist_GPRS_multislot_class); printf("class %d\n", cap->MS_RA_capability_value[i].u.Content.Multislot_capability.GPRS_multislot_class); ... the output continues as this: we have = 2 index=2 exists multislot capability 0 exists class 1 class 10 index=0 exists multislot capability 0 exists class 0 class 0 the "class 10" is correct, also it is correct that the class only exists in the first entry of the capability array. the output of the dissector states that multislot capability exists (Exist_Multislot_capability = 1), but if i look at the structure, this field is not set. i looked at the dissector code, but don't really understand why CSN_NEXT_EXIST works for some elements and not for others. any ideas? regards, andreas

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[ANNOUNCE] OsmoDevCon 2013-04-04 till 2013-04-07, Berlin
by Harald Welte 26 Feb '13

26 Feb '13

Dear fellow Osmcoom developers, it is my pleasure to finally announce the date + venue of OsmoDevCon 2013: Date: April 04 through April 07, 2013 Place: IN-Berlin, Lehrter Str. 53, Berlin Like last year, this is an event for developers of the various Osmocom proejects. Reservation and confirmation of reservation is required. The event is free of charge. The Room is made available by IN-Berlin e.V., an Internet related non-profit organization. Lunch catering will be sponsored (so far by sysmocom GmbH, but if any other sponsors come up, we are happy to share the cost). So all you have to cover is your own travel + accomodation costs, as well as breakfast and dinner. If you are an active developer and cannot afford travel/accomodation, please let me know and I'll see if we can do something about it. If you would like to attend, please send a message to laforge(a)gnumonks.org applying for registration of the event. The registration deadline is March 5, i.e. one week from now. There is no detailed schedule of talks yet. I will start a separate discussion suggesting / collecting topics in the next couple of days. More information is (and will be made) available at http://openbsc.osmocom.org/trac/wiki/OsmoDevCon2013 Further discussion regarding the event should be directed at the osmocom-event-orga(a)lists.osmocom.org mailing list, to avoid cross-posting over the various project-specific lists. Best regards and happy hacking, Harald -- - Harald Welte <laforge(a)gnumonks.org> http://laforge.gnumonks.org/ ============================================================================ "Privacy in residential applications is a desirable marketing option." (ETSI EN 300 175-7 Ch. A6)

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Invalid decoding of some PACKET_RESOURCE_REQUESTs
by Steve Markgraf 19 Feb '13

19 Feb '13

Hi, I noticed a bug in the dissector, which seems to happen when then Exist_A5_bits field is set to 0, and results in the following fields (Exist_Multislot_capability/Exist_GPRS_multislot_class) being decoded incorrectly. Thus, get_ms_class_by_capability() is returning NULL instead of the GPRS_multislot_class, which is interestingly dissected correctly. This is one of the messages where this happens: 4017dfb83a3f628a7045500898f28109100297e0080b2b If I add it to the RLCMACTest it fails, so I propose it should be added ;) My quite recent version of Wireshark (1.8.2) is decoding this message fine, see the attachment. I've gone through the recent changes on packet-gsm_rlcmac.c and packet-csn1.c in Wireshark, but couldn't spot the commit that fixed it so far. Regards, Steve

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osmocom-net-gprs February 2013