Change in osmo-pcu[master]: csn1: Avoid storing existance bit as true if content was actually NULL

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pespin gerrit-no-reply at lists.osmocom.org
Tue Oct 19 15:55:23 UTC 2021


pespin has uploaded this change for review. ( https://gerrit.osmocom.org/c/osmo-pcu/+/25831 )


Change subject: csn1: Avoid storing existance bit as true if content was actually NULL
......................................................................

csn1: Avoid storing existance bit as true if content was actually NULL

If we decode Exist bit as "1" but we are at the end of the message, and
all the Next items we'd read are expected to be possibly NULL, then swap
the Exist bit in the decoded structure as "0" in order to tell the
decoder user that the related information structure is actually unset,
as if "0" was received.

Related: SYS#5552
Related: OS#4955
Related: OS#5020
Change-Id: I38602e4b680ed87297c7e440691a494c07cad446
---
M src/csn1_dec.c
M tests/rlcmac/RLCMACTest.err
2 files changed, 37 insertions(+), 7 deletions(-)



  git pull ssh://gerrit.osmocom.org:29418/osmo-pcu refs/changes/31/25831/1

diff --git a/src/csn1_dec.c b/src/csn1_dec.c
index 4bc74f3..fa1f0c3 100644
--- a/src/csn1_dec.c
+++ b/src/csn1_dec.c
@@ -909,6 +909,7 @@
       case CSN_NEXT_EXIST:
       {
         guint8 fExist;
+        guint8 isnull;
 
         pui8  = pui8DATA(data, pDescr->offset);
 
@@ -927,17 +928,30 @@
         /* the "regular" M_NEXT_EXIST description element */
 
         fExist = 0x00;
+        isnull = 1;
 	if (bitvec_read_field(vector, readIndex, 1))
         {
           fExist = 0x01;
+          if (remaining_bits_len == 1) {
+             /* If { 1 < end > } and all next items may be null, store it as { 0 } */
+            const CSN_DESCR* pDescrNext = pDescr + 1;
+            guint8 i;
+            for (i = 0; i < pDescr->i; i++, pDescrNext++)
+            {
+              if (!pDescrNext->may_be_null)
+                isnull = 0;
+            }
+          } else {
+            isnull = 0;
+          }
         }
 
-        *pui8     = fExist;
+        *pui8     = !isnull;
         remaining_bits_len -= 1;
-        LOGPC(DCSN1, LOGL_DEBUG, "%s = %u | ", pDescr->sz , (unsigned)*pui8);
+        LOGPC(DCSN1, LOGL_DEBUG, "%s = %u%s | ", pDescr->sz, (unsigned)fExist, fExist && isnull ? " (NULL)" : "");
         ++bit_offset;
 
-        if (fExist == 0)
+        if (isnull)
         { /* Skip 'i' entries */
           pDescr += pDescr->i;
         }
@@ -949,6 +963,7 @@
       case CSN_NEXT_EXIST_LH:
       {
         guint8 fExist;
+        guint8 isnull;
         pui8  = pui8DATA(data, pDescr->offset);
 
         /* this if-statement represents the M_NEXT_EXIST_OR_NULL_LH description element */
@@ -964,14 +979,29 @@
         }
 
         /* the "regular" M_NEXT_EXIST_LH description element */
-        fExist = get_masked_bits8(vector, readIndex, bit_offset, 1);
-        LOGPC(DCSN1, LOGL_DEBUG, "%s = %u | ", pDescr->sz , (unsigned)fExist);
+        isnull = 1;
+        if ((fExist = get_masked_bits8(vector, readIndex, bit_offset, 1)))
+        {
+          if (remaining_bits_len == 1) {
+             /* If { 1 < end > } and all next items may be null, store it as { 0 } */
+            const CSN_DESCR* pDescrNext = pDescr + 1;
+            guint8 i;
+            for (i = 0; i < pDescr->i; i++, pDescrNext++)
+            {
+              if (!pDescrNext->may_be_null)
+                isnull = 0;
+            }
+          } else {
+            isnull = 0;
+          }
+        }
+        LOGPC(DCSN1, LOGL_DEBUG, "%s = %u%s | ", pDescr->sz , (unsigned)fExist, fExist && isnull ? " (NULL)" : "");
         *pui8++   = fExist;
         remaining_bits_len -= 1;
 
         bit_offset++;
 
-        if (fExist == 0)
+        if (isnull)
         { /* Skip 'i' entries */
           pDescr += pDescr->i;
         }
diff --git a/tests/rlcmac/RLCMACTest.err b/tests/rlcmac/RLCMACTest.err
index 33a47c3..1dc8d04 100644
--- a/tests/rlcmac/RLCMACTest.err
+++ b/tests/rlcmac/RLCMACTest.err
@@ -58,4 +58,4 @@
 DCSN1 DEBUG csnStreamDecoder (EGPRS Packet Channel Request): Choice EGPRS_PacketChannelRequest_Choice = 51 |  : Content | RandomBits = 17 | : End Content | 
 DCSN1 DEBUG csnStreamDecoder (EGPRS Packet Channel Request): Choice EGPRS_PacketChannelRequest_Choice = 55 |  : Content | RandomBits = 25 | : End Content | 
 DCSN1 DEBUG csnStreamDecoder (EGPRS Packet Channel Request): DCSN1 ERROR csnStreamDecoder: error STREAM_NOT_SUPPORTED (-8) at EGPRS_PacketChannelRequest_Choice (idx 0)
-DCSN1 INFO csnStreamDecoder (RAcap): MS_RA_capability_value { | Choice MS_RA_capability_value_Choice = 1 | u.Content length = 61 | offset = 1 | RF_Power_Capability = 4 | Exist_A5_bits = 1 | A5_bits = 80 | ES_IND = 1 | PS = 1 | VGCS = 0 | VBS = 0 | Exist_Multislot_capability = 1 |  : Multislot_capability | Exist_HSCSD_multislot_class = 0 | Exist_GPRS_multislot_class = 1 | GPRS_multislot_class = 12 | GPRS_Extended_Dynamic_Allocation_Capability = 1 | Exist_SM = 0 | Exist_ECSD_multislot_class = 0 | Exist_EGPRS_multislot_class = 1 | EGPRS_multislot_class = 12 | EGPRS_Extended_Dynamic_Allocation_Capability = 1 | Exist_DTM_GPRS_multislot_class = 0 | : End Multislot_capability | Exist_Eight_PSK_Power_Capability = 1 | Eight_PSK_Power_Capability = 2 | COMPACT_Interference_Measurement_Capability = 0 | Revision_Level_Indicator = 1 | UMTS_FDD_Radio_Access_Technology_Capability = 1 | UMTS_384_TDD_Radio_Access_Technology_Capability = 0 | CDMA2000_Radio_Access_Technology_Capability = 0 | UMTS_128_TDD_Radio_Access_Technology_Capability = 0 | GERAN_Feature_Package_1 = 1 | Exist_Extended_DTM_multislot_class = 0 | Modulation_based_multislot_class_support = 0 | Exist_HighMultislotCapability = 0 | Exist_GERAN_lu_ModeCapability = 0 | GMSK_MultislotPowerProfile = 0 | EightPSK_MultislotProfile = 0 | MultipleTBF_Capability = 0 | DownlinkAdvancedReceiverPerformance = 0 | ExtendedRLC_MAC_ControlMessageSegmentionsCapability = 0 | DTM_EnhancementsCapability = 0 | Exist_DTM_GPRS_HighMultislotClass = 0 | PS_HandoverCapability = 0 | DTM_Handover_Capability = 0 | Exist_DownlinkDualCarrierCapability_r7 = 1 |  : DownlinkDualCarrierCapability_r7 = NULL | FlexibleTimeslotAssignment = NULL | GAN_PS_HandoverCapability = NULL | RLC_Non_persistentMode = NULL | ReducedLatencyCapability = NULL | UplinkEGPRS2 = NULL | DownlinkEGPRS2 = NULL | EUTRA_FDD_Support = NULL | EUTRA_TDD_Support = NULL | GERAN_To_EUTRAN_supportInGERAN_PTM = NULL | PriorityBasedReselectionSupport = NULL | MS_RA_capability_value } | MS_RA_capability_value { | Choice MS_RA_capability_value_Choice = 3 | u.Content length = 36 | offset = 1 | RF_Power_Capability = 1 | Exist_A5_bits = 0 | ES_IND = 1 | PS = 1 | VGCS = 0 | VBS = 0 | Exist_Multislot_capability = 0 | Exist_Eight_PSK_Power_Capability = 1 | Eight_PSK_Power_Capability = 2 | COMPACT_Interference_Measurement_Capability = 0 | Revision_Level_Indicator = 1 | UMTS_FDD_Radio_Access_Technology_Capability = 1 | UMTS_384_TDD_Radio_Access_Technology_Capability = 0 | CDMA2000_Radio_Access_Technology_Capability = 0 | UMTS_128_TDD_Radio_Access_Technology_Capability = 0 | GERAN_Feature_Package_1 = 1 | Exist_Extended_DTM_multislot_class = 0 | Modulation_based_multislot_class_support = 0 | Exist_HighMultislotCapability = 0 | Exist_GERAN_lu_ModeCapability = 0 | GMSK_MultislotPowerProfile = 0 | EightPSK_MultislotProfile = 0 | MultipleTBF_Capability = 0 | DownlinkAdvancedReceiverPerformance = 0 | ExtendedRLC_MAC_ControlMessageSegmentionsCapability = 0 | DTM_EnhancementsCapability = 0 | Exist_DTM_GPRS_HighMultislotClass = 0 | PS_HandoverCapability = 0 | DTM_Handover_Capability = 0 | Exist_DownlinkDualCarrierCapability_r7 = 1 |  : DownlinkDualCarrierCapability_r7 = NULL | FlexibleTimeslotAssignment = NULL | GAN_PS_HandoverCapability = NULL | RLC_Non_persistentMode = NULL | ReducedLatencyCapability = NULL | UplinkEGPRS2 = NULL | DownlinkEGPRS2 = NULL | EUTRA_FDD_Support = NULL | EUTRA_TDD_Support = NULL | GERAN_To_EUTRAN_supportInGERAN_PTM = NULL | PriorityBasedReselectionSupport = NULL | MS_RA_capability_value } | MS_RA_capability_value { | Choice MS_RA_capability_value_Choice = 7 | u.Content length = 36 | offset = 1 | RF_Power_Capability = 4 | Exist_A5_bits = 0 | ES_IND = 1 | PS = 1 | VGCS = 0 | VBS = 0 | Exist_Multislot_capability = 0 | Exist_Eight_PSK_Power_Capability = 1 | Eight_PSK_Power_Capability = 2 | COMPACT_Interference_Measurement_Capability = 0 | Revision_Level_Indicator = 1 | UMTS_FDD_Radio_Access_Technology_Capability = 1 | UMTS_384_TDD_Radio_Access_Technology_Capability = 0 | CDMA2000_Radio_Access_Technology_Capability = 0 | UMTS_128_TDD_Radio_Access_Technology_Capability = 0 | GERAN_Feature_Package_1 = 1 | Exist_Extended_DTM_multislot_class = 0 | Modulation_based_multislot_class_support = 0 | Exist_HighMultislotCapability = 0 | Exist_GERAN_lu_ModeCapability = 0 | GMSK_MultislotPowerProfile = 0 | EightPSK_MultislotProfile = 0 | MultipleTBF_Capability = 0 | DownlinkAdvancedReceiverPerformance = 0 | ExtendedRLC_MAC_ControlMessageSegmentionsCapability = 0 | DTM_EnhancementsCapability = 0 | Exist_DTM_GPRS_HighMultislotClass = 0 | PS_HandoverCapability = 0 | DTM_Handover_Capability = 0 | Exist_DownlinkDualCarrierCapability_r7 = 1 |  : DownlinkDualCarrierCapability_r7 = NULL | FlexibleTimeslotAssignment = NULL | GAN_PS_HandoverCapability = NULL | RLC_Non_persistentMode = NULL | ReducedLatencyCapability = NULL | UplinkEGPRS2 = NULL | DownlinkEGPRS2 = NULL | EUTRA_FDD_Support = NULL | EUTRA_TDD_Support = NULL | GERAN_To_EUTRAN_supportInGERAN_PTM = NULL | PriorityBasedReselectionSupport = NULL | MS_RA_capability_value } | Padding = 0|
+DCSN1 INFO csnStreamDecoder (RAcap): MS_RA_capability_value { | Choice MS_RA_capability_value_Choice = 1 | u.Content length = 61 | offset = 1 | RF_Power_Capability = 4 | Exist_A5_bits = 1 | A5_bits = 80 | ES_IND = 1 | PS = 1 | VGCS = 0 | VBS = 0 | Exist_Multislot_capability = 1 |  : Multislot_capability | Exist_HSCSD_multislot_class = 0 | Exist_GPRS_multislot_class = 1 | GPRS_multislot_class = 12 | GPRS_Extended_Dynamic_Allocation_Capability = 1 | Exist_SM = 0 | Exist_ECSD_multislot_class = 0 | Exist_EGPRS_multislot_class = 1 | EGPRS_multislot_class = 12 | EGPRS_Extended_Dynamic_Allocation_Capability = 1 | Exist_DTM_GPRS_multislot_class = 0 | : End Multislot_capability | Exist_Eight_PSK_Power_Capability = 1 | Eight_PSK_Power_Capability = 2 | COMPACT_Interference_Measurement_Capability = 0 | Revision_Level_Indicator = 1 | UMTS_FDD_Radio_Access_Technology_Capability = 1 | UMTS_384_TDD_Radio_Access_Technology_Capability = 0 | CDMA2000_Radio_Access_Technology_Capability = 0 | UMTS_128_TDD_Radio_Access_Technology_Capability = 0 | GERAN_Feature_Package_1 = 1 | Exist_Extended_DTM_multislot_class = 0 | Modulation_based_multislot_class_support = 0 | Exist_HighMultislotCapability = 0 | Exist_GERAN_lu_ModeCapability = 0 | GMSK_MultislotPowerProfile = 0 | EightPSK_MultislotProfile = 0 | MultipleTBF_Capability = 0 | DownlinkAdvancedReceiverPerformance = 0 | ExtendedRLC_MAC_ControlMessageSegmentionsCapability = 0 | DTM_EnhancementsCapability = 0 | Exist_DTM_GPRS_HighMultislotClass = 0 | PS_HandoverCapability = 0 | DTM_Handover_Capability = 0 | Exist_DownlinkDualCarrierCapability_r7 = 1 (NULL) | FlexibleTimeslotAssignment = NULL | GAN_PS_HandoverCapability = NULL | RLC_Non_persistentMode = NULL | ReducedLatencyCapability = NULL | UplinkEGPRS2 = NULL | DownlinkEGPRS2 = NULL | EUTRA_FDD_Support = NULL | EUTRA_TDD_Support = NULL | GERAN_To_EUTRAN_supportInGERAN_PTM = NULL | PriorityBasedReselectionSupport = NULL | MS_RA_capability_value } | MS_RA_capability_value { | Choice MS_RA_capability_value_Choice = 3 | u.Content length = 36 | offset = 1 | RF_Power_Capability = 1 | Exist_A5_bits = 0 | ES_IND = 1 | PS = 1 | VGCS = 0 | VBS = 0 | Exist_Multislot_capability = 0 | Exist_Eight_PSK_Power_Capability = 1 | Eight_PSK_Power_Capability = 2 | COMPACT_Interference_Measurement_Capability = 0 | Revision_Level_Indicator = 1 | UMTS_FDD_Radio_Access_Technology_Capability = 1 | UMTS_384_TDD_Radio_Access_Technology_Capability = 0 | CDMA2000_Radio_Access_Technology_Capability = 0 | UMTS_128_TDD_Radio_Access_Technology_Capability = 0 | GERAN_Feature_Package_1 = 1 | Exist_Extended_DTM_multislot_class = 0 | Modulation_based_multislot_class_support = 0 | Exist_HighMultislotCapability = 0 | Exist_GERAN_lu_ModeCapability = 0 | GMSK_MultislotPowerProfile = 0 | EightPSK_MultislotProfile = 0 | MultipleTBF_Capability = 0 | DownlinkAdvancedReceiverPerformance = 0 | ExtendedRLC_MAC_ControlMessageSegmentionsCapability = 0 | DTM_EnhancementsCapability = 0 | Exist_DTM_GPRS_HighMultislotClass = 0 | PS_HandoverCapability = 0 | DTM_Handover_Capability = 0 | Exist_DownlinkDualCarrierCapability_r7 = 1 (NULL) | FlexibleTimeslotAssignment = NULL | GAN_PS_HandoverCapability = NULL | RLC_Non_persistentMode = NULL | ReducedLatencyCapability = NULL | UplinkEGPRS2 = NULL | DownlinkEGPRS2 = NULL | EUTRA_FDD_Support = NULL | EUTRA_TDD_Support = NULL | GERAN_To_EUTRAN_supportInGERAN_PTM = NULL | PriorityBasedReselectionSupport = NULL | MS_RA_capability_value } | MS_RA_capability_value { | Choice MS_RA_capability_value_Choice = 7 | u.Content length = 36 | offset = 1 | RF_Power_Capability = 4 | Exist_A5_bits = 0 | ES_IND = 1 | PS = 1 | VGCS = 0 | VBS = 0 | Exist_Multislot_capability = 0 | Exist_Eight_PSK_Power_Capability = 1 | Eight_PSK_Power_Capability = 2 | COMPACT_Interference_Measurement_Capability = 0 | Revision_Level_Indicator = 1 | UMTS_FDD_Radio_Access_Technology_Capability = 1 | UMTS_384_TDD_Radio_Access_Technology_Capability = 0 | CDMA2000_Radio_Access_Technology_Capability = 0 | UMTS_128_TDD_Radio_Access_Technology_Capability = 0 | GERAN_Feature_Package_1 = 1 | Exist_Extended_DTM_multislot_class = 0 | Modulation_based_multislot_class_support = 0 | Exist_HighMultislotCapability = 0 | Exist_GERAN_lu_ModeCapability = 0 | GMSK_MultislotPowerProfile = 0 | EightPSK_MultislotProfile = 0 | MultipleTBF_Capability = 0 | DownlinkAdvancedReceiverPerformance = 0 | ExtendedRLC_MAC_ControlMessageSegmentionsCapability = 0 | DTM_EnhancementsCapability = 0 | Exist_DTM_GPRS_HighMultislotClass = 0 | PS_HandoverCapability = 0 | DTM_Handover_Capability = 0 | Exist_DownlinkDualCarrierCapability_r7 = 1 (NULL) | FlexibleTimeslotAssignment = NULL | GAN_PS_HandoverCapability = NULL | RLC_Non_persistentMode = NULL | ReducedLatencyCapability = NULL | UplinkEGPRS2 = NULL | DownlinkEGPRS2 = NULL | EUTRA_FDD_Support = NULL | EUTRA_TDD_Support = NULL | GERAN_To_EUTRAN_supportInGERAN_PTM = NULL | PriorityBasedReselectionSupport = NULL | MS_RA_capability_value } | Padding = 0|

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Gerrit-Project: osmo-pcu
Gerrit-Branch: master
Gerrit-Change-Id: I38602e4b680ed87297c7e440691a494c07cad446
Gerrit-Change-Number: 25831
Gerrit-PatchSet: 1
Gerrit-Owner: pespin <pespin at sysmocom.de>
Gerrit-MessageType: newchange
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