NB-IoT SRB1bis implementation

Change-Id: If0c9dd3f3ca2321aaf9176330299a32f611d34ce
Reviewed-on: https://code.wireshark.org/review/20990
Petri-Dish: Pascal Quantin <pascal.quantin@gmail.com>
Tested-by: Petri Dish Buildbot <buildbot-no-reply@wireshark.org>
Reviewed-by: Pascal Quantin <pascal.quantin@gmail.com>

3 files changed, 42 insertions, 10 deletions

diff --git a/epan/dissectors/packet-mac-lte.c b/epan/dissectors/packet-mac-lte.c
index a65ce97ace..f6339e302e 100644
--- a/epan/dissectors/packet-mac-lte.c
+++ b/epan/dissectors/packet-mac-lte.c
@@ -3371,7 +3371,7 @@ static void call_rlc_dissector(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tr
                                guint8 mode, guint8 direction, guint16 ueid,
                                guint16 channelType, guint16 channelId,
                                guint8 sequenceNumberLength,
-                               guint8 priority, gboolean rlcExtLiField)
+                               guint8 priority, gboolean rlcExtLiField, mac_lte_nb_mode nbMode)
 {
     tvbuff_t            *rb_tvb = tvb_new_subset_length(tvb, offset, data_length);
     struct rlc_lte_info *p_rlc_lte_info;
@@ -3392,6 +3392,11 @@ static void call_rlc_dissector(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tr
     p_rlc_lte_info->pduLength = data_length;
     p_rlc_lte_info->sequenceNumberLength = sequenceNumberLength;
     p_rlc_lte_info->extendedLiField = rlcExtLiField;
+    if (nbMode == nb_mode) {
+        p_rlc_lte_info->nbMode = rlc_nb_mode;
+    } else {
+        p_rlc_lte_info->nbMode = rlc_no_nb_mode;
+    }
 
     /* Store info in packet */
     p_add_proto_data(wmem_file_scope(), pinfo, proto_rlc_lte, 0, p_rlc_lte_info);
@@ -5694,7 +5699,9 @@ static void dissect_ulsch_or_dlsch(tvbuff_t *tvb, packet_info *pinfo, proto_tree
         }
 
         /* LCID 1 and 2 can be assumed to be srb1&2, so can dissect as RLC AM */
-        else if ((lcids[n] == 1) || (lcids[n] == 2)) {
+        /* LCID 3 in NB mode can be assumed to be srb1bis, so can dissect as RLC AM */
+        else if ((lcids[n] == 1) || (lcids[n] == 2) ||
+                 (p_mac_lte_info->nbMode == nb_mode && lcids[n] == 3)) {
             if (global_mac_lte_attempt_srb_decode) {
                 /* Call RLC dissector */
                 call_rlc_dissector(tvb, pinfo, tree, pdu_ti, offset, data_length,
@@ -5702,7 +5709,7 @@ static void dissect_ulsch_or_dlsch(tvbuff_t *tvb, packet_info *pinfo, proto_tree
                                    CHANNEL_TYPE_SRB, lcids[n], 0,
                                    get_mac_lte_channel_priority(p_mac_lte_info->ueid,
                                                                 lcids[n], p_mac_lte_info->direction),
-                                   FALSE);
+                                   FALSE, p_mac_lte_info->nbMode);
 
                 /* Hide raw view of bytes */
                 PROTO_ITEM_SET_HIDDEN(sdu_ti);
@@ -5735,7 +5742,7 @@ static void dissect_ulsch_or_dlsch(tvbuff_t *tvb, packet_info *pinfo, proto_tree
                     call_rlc_dissector(tvb, pinfo, tree, pdu_ti, offset, data_length,
                                        RLC_UM_MODE, p_mac_lte_info->direction, p_mac_lte_info->ueid,
                                        CHANNEL_TYPE_DRB, (guint16)drb_id, seqnum_length,
-                                       priority, FALSE);
+                                       priority, FALSE, p_mac_lte_info->nbMode);
                     break;
                 case rlcAM:
                 case rlcAMulExtLiField:
@@ -5756,13 +5763,13 @@ static void dissect_ulsch_or_dlsch(tvbuff_t *tvb, packet_info *pinfo, proto_tree
                     call_rlc_dissector(tvb, pinfo, tree, pdu_ti, offset, data_length,
                                        RLC_AM_MODE, p_mac_lte_info->direction, p_mac_lte_info->ueid,
                                        CHANNEL_TYPE_DRB, (guint16)drb_id, seqnum_length,
-                                       priority, rlc_ext_li_field);
+                                       priority, rlc_ext_li_field, p_mac_lte_info->nbMode);
                     break;
                 case rlcTM:
                     call_rlc_dissector(tvb, pinfo, tree, pdu_ti, offset, data_length,
                                        RLC_TM_MODE, p_mac_lte_info->direction, p_mac_lte_info->ueid,
                                        CHANNEL_TYPE_DRB, (guint16)drb_id, 0,
-                                       priority, FALSE);
+                                       priority, FALSE, p_mac_lte_info->nbMode);
                     break;
                 case rlcRaw:
                     /* Nothing to do! */
@@ -6219,12 +6226,12 @@ static void dissect_mch(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, pro
             /* Call RLC dissector */
             call_rlc_dissector(tvb, pinfo, tree, pdu_ti, offset, data_length,
                                RLC_UM_MODE, DIRECTION_DOWNLINK, 0,
-                               CHANNEL_TYPE_MCCH, 0, 5, 0, FALSE);
+                               CHANNEL_TYPE_MCCH, 0, 5, 0, FALSE, p_mac_lte_info->nbMode);
         } else if ((lcids[n] <= 28) && global_mac_lte_call_rlc_for_mtch) {
             /* Call RLC dissector */
             call_rlc_dissector(tvb, pinfo, tree, pdu_ti, offset, data_length,
                                RLC_UM_MODE, DIRECTION_DOWNLINK, 0,
-                               CHANNEL_TYPE_MTCH, 0, 5, 0, FALSE);
+                               CHANNEL_TYPE_MTCH, 0, 5, 0, FALSE, p_mac_lte_info->nbMode);
         } else {
             /* Dissect SDU as raw bytes */
             sdu_ti = proto_tree_add_bytes_format(tree, hf_mac_lte_mch_sdu, tvb, offset, pdu_lengths[n],
diff --git a/epan/dissectors/packet-rlc-lte.c b/epan/dissectors/packet-rlc-lte.c
index 3322eef328..4e9a0db14a 100644
--- a/epan/dissectors/packet-rlc-lte.c
+++ b/epan/dissectors/packet-rlc-lte.c
@@ -829,7 +829,11 @@ static void show_PDU_in_tree(packet_info *pinfo, proto_tree *tree, tvbuff_t *tvb
             }
 
             p_pdcp_lte_info->ueid = rlc_info->ueid;
-            p_pdcp_lte_info->channelType = Channel_DCCH;
+            if (rlc_info->nbMode == rlc_nb_mode) {
+                p_pdcp_lte_info->channelType = Channel_DCCH_NB;
+            } else {
+                p_pdcp_lte_info->channelType = Channel_DCCH;
+            }
             p_pdcp_lte_info->channelId = rlc_info->channelId;
             p_pdcp_lte_info->direction = rlc_info->direction;
             p_pdcp_lte_info->is_retx = (state != SN_OK);
@@ -838,7 +842,12 @@ static void show_PDU_in_tree(packet_info *pinfo, proto_tree *tree, tvbuff_t *tvb
             p_pdcp_lte_info->no_header_pdu = FALSE;
             if (rlc_info->channelType == CHANNEL_TYPE_SRB) {
                 p_pdcp_lte_info->plane = SIGNALING_PLANE;
-                p_pdcp_lte_info->seqnum_length = 5;
+                if ((rlc_info->nbMode == rlc_nb_mode) && (rlc_info->channelId == 3)) {
+                    p_pdcp_lte_info->no_header_pdu = TRUE;
+                    p_pdcp_lte_info->seqnum_length = 0;
+                } else {
+                    p_pdcp_lte_info->seqnum_length = 5;
+                }
             }
             else {
                 p_pdcp_lte_info->plane = USER_PLANE;
@@ -2831,6 +2840,11 @@ static gboolean dissect_rlc_lte_heur(tvbuff_t *tvb, packet_info *pinfo,
             case RLC_LTE_EXT_LI_FIELD_TAG:
                 p_rlc_lte_info->extendedLiField = TRUE;
                 break;
+            case RLC_LTE_NB_MODE_TAG:
+                p_rlc_lte_info->nbMode =
+                    (rlc_lte_nb_mode)tvb_get_guint8(tvb, offset);
+                offset++;
+                break;
 
             case RLC_LTE_PAYLOAD_TAG:
                 /* Have reached data, so set payload length and get out of loop */
diff --git a/epan/dissectors/packet-rlc-lte.h b/epan/dissectors/packet-rlc-lte.h
index 4b37ccac4b..103ae1c8ab 100644
--- a/epan/dissectors/packet-rlc-lte.h
+++ b/epan/dissectors/packet-rlc-lte.h
@@ -51,6 +51,13 @@
 #define AM_SN_LENGTH_10_BITS 10
 #define AM_SN_LENGTH_16_BITS 16
 
+
+typedef enum rlc_lte_nb_mode {
+    rlc_no_nb_mode = 0,
+    rlc_nb_mode = 1
+} rlc_lte_nb_mode;
+
+
 /* Info attached to each LTE RLC frame */
 typedef struct rlc_lte_info
 {
@@ -63,6 +70,7 @@ typedef struct rlc_lte_info
     guint16         channelId;
     guint16         pduLength;
     gboolean        extendedLiField;
+    rlc_lte_nb_mode nbMode;
 } rlc_lte_info;
 
 
@@ -155,6 +163,9 @@ void set_rlc_lte_drb_li_field(packet_info *pinfo, guint16 ueid, guint8 drbid, gb
 #define RLC_LTE_EXT_LI_FIELD_TAG    0x08
 /* 0 byte, tag presence indicates that AM DRB PDU is using an extended LI field of 15 bits */
 
+#define RLC_LTE_NB_MODE_TAG         0x09
+/* 1 byte containing rlc_lte_nb_mode enum value */
+
 /* RLC PDU. Following this tag comes the actual RLC PDU (there is no length, the PDU
    continues until the end of the frame) */
 #define RLC_LTE_PAYLOAD_TAG         0x01