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Bug #3249
closedosmo-bts sends UNIT_DATA_IND with non-permitted extra IEs
Start date:
05/08/2018
Due date:
% Done:
80%
Spec Reference:
Description
TS 48.058 defines the "RLL UNIT DATA INDICATION" in section 8.3.11 as a message containing only
- message discriminator
- message type
- channel number
- link identifier
- l3 information
However, osmo-bts generates
{ iei := RSL_IE_CHAN_NR (1), body := { chan_nr := { u := { sdcch4 := { tag := '001'B, sub_chan := 2 } }, tn := 0 } } }, { iei := RSL_IE_LINK_IDENT (2), body := { link_id := { c := FACCH_SDCCH (0), na := false, prio := SAPI0_PRIO_NORMAL (0), sapi := 0 } } }, { iei := RSL_IE_TIMING_ADVANCE (24), body := { timing_adv := 0 } }, { iei := RSL_IE_MS_POWER (13), body := { ms_power := { reserved := 0, fpc_epc := false, power_level := 0 } } }, { iei := RSL_IE_L3_INFO (11), body := { l3_info := { len := 15, payload := '43DF4F33FBB9A35A7B0399F5937ADB'O } } }
as you can see, this includes MS_POWER and TIMING_ADVANCE IEs that shouldn't be there.
This was generated from a LAPDm frame on a SDCCH as follows:
21:12:03.500544 6 BTS_Tests.ttcn:3021 enc_LapdmFrame(): Stream after encoding: '01033D43DF4F33FBB9A35A7B0399F5937ADB'O 21:12:03.500833 6 BTS_Tests.ttcn:3026 encoding { ab := { addr := { spare := '0'B, lpd := 0, sapi := 0, c_r := false, ea := true }, ctrl := { u := { spare := '11'B, u2 := '00'B, p_f := false, u := '000'B } }, len := 0, m := false, el := 1, payload := '43DF4F33FBB9A35A7B0399F5937ADB'O } } to '01033D43DF4F33FBB9A35A7B0399F5937ADB'O
Updated by laforge almost 6 years ago
- % Done changed from 0 to 10
the culprit appears to be send_rslms_rll_l3_ui()
in libosmocore/src/gsm/lapdm.c
, whihc talks about Take a B4 format message from L1 and create RSLms UNIT DATA IND to go on and add unconditional RSL_IE_TIMING_ADVANCE and RSL_IE_MS_POWER.
However, we're calling this for any OSMO_PRIM(PRIM_DL_UNIT_DATA, PRIM_OP_INDICATION)
, which is how the LAPD code reports any UI frame, no matter where it was received on.
Updated by laforge almost 6 years ago
- Status changed from New to In Progress
- Assignee set to laforge
- % Done changed from 10 to 80
https://gerrit.osmocom.org/8076 contains a proposed fix
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