UMTS Iub: Resolve U-RNTI for C-RNTI

This commit includes logic used to store pairs of C-RNTIs and U-RNTIs based on allocations in RRC and logic to retrive those when encountering C-RNTIs in the MAC header for DCCH over FACH/RACH.

Change-Id: I629ab061b7a73416e5730a980480b81a1aaade11
Reviewed-on: https://code.wireshark.org/review/21607
Petri-Dish: Anders Broman <a.broman58@gmail.com>
Tested-by: Petri Dish Buildbot <buildbot-no-reply@wireshark.org>
Reviewed-by: Anders Broman <a.broman58@gmail.com>

1 files changed, 79 insertions, 2 deletions

diff --git a/epan/dissectors/packet-umts_mac.c b/epan/dissectors/packet-umts_mac.c
index 70dcca49da..9d4ef97e1b 100644
--- a/epan/dissectors/packet-umts_mac.c
+++ b/epan/dissectors/packet-umts_mac.c
@@ -47,6 +47,8 @@ static int hf_mac_ct = -1;
 static int hf_mac_ueid_type = -1;
 static int hf_mac_crnti = -1;
 static int hf_mac_urnti = -1;
+static int hf_mac_resolved_urnti = -1;
+static int hf_mac_crnti_urnti_match_frame = -1;
 static int hf_mac_channel = -1;
 /* static int hf_mac_channel_str = -1; */
 
@@ -78,6 +80,7 @@ static int ett_mac_edch = -1;
 static int ett_mac_hsdsch = -1;
 static int ett_mac_edch_type2 = -1;
 static int ett_mac_edch_type2_sdu = -1;
+static int ett_mac_resolved_urnti = -1;
 
 static expert_field ei_mac_cs_dtch_not_implemented = EI_INIT;
 static expert_field ei_mac_rach_tctf_unknown = EI_INIT;
@@ -231,6 +234,12 @@ static guint16 tree_add_common_dcch_dtch_fields(tvbuff_t *tvb, packet_info *pinf
     proto_tree *tree, guint16 bitoffs, fp_info *fpinf, umts_mac_info *macinf, rlc_info  *rlcinf)
 {
     guint8 ueid_type;
+    conversation_t   *p_conv;
+    umts_fp_conversation_info_t *umts_fp_conversation_info = NULL;
+    fp_rach_channel_info_t *fp_rach_channel_info = NULL;
+    fp_fach_channel_info_t *fp_fach_channel_info = NULL;
+    guint16 c_rnti;
+    fp_crnti_allocation_info_t *fp_crnti_allocation_info = NULL;
 
     ueid_type = tvb_get_bits8(tvb, bitoffs, 2);
     proto_tree_add_bits_item(tree, hf_mac_ueid_type, tvb, bitoffs, 2, ENC_BIG_ENDIAN);
@@ -241,7 +250,62 @@ static guint16 tree_add_common_dcch_dtch_fields(tvbuff_t *tvb, packet_info *pinf
         bitoffs += 32;
     } else if (ueid_type == MAC_UEID_TYPE_CRNTI) {
         proto_tree_add_bits_item(tree, hf_mac_crnti, tvb, 4, 16, ENC_BIG_ENDIAN);
-        rlcinf->urnti[fpinf->cur_tb] = tvb_get_bits16(tvb, bitoffs, 16,ENC_BIG_ENDIAN);
+        c_rnti = tvb_get_bits16(tvb, bitoffs, 16,ENC_BIG_ENDIAN);
+        p_conv = (conversation_t *)find_conversation(pinfo->num, &pinfo->net_dst, &pinfo->net_src,
+                        pinfo->ptype,
+                        pinfo->destport, pinfo->srcport, NO_ADDR_B);
+        if (p_conv != NULL) {
+            umts_fp_conversation_info = (umts_fp_conversation_info_t *)conversation_get_proto_data(p_conv, proto_fp);
+        }
+        /* Trying to resolve the U-RNTI for this C-RNTI based on the channel type*/
+        switch(fpinf->channel){
+            case CHANNEL_RACH_FDD:
+                /* In RACH: First look in the channel's RNTIs map */
+                if (umts_fp_conversation_info) {
+                    fp_rach_channel_info = (fp_rach_channel_info_t *)umts_fp_conversation_info->channel_specific_info;
+                    if(fp_rach_channel_info) {
+                        fp_crnti_allocation_info = (fp_crnti_allocation_info_t *)wmem_tree_lookup32(fp_rach_channel_info->crnti_to_urnti_map, c_rnti);
+                    }
+                }
+                if(fp_crnti_allocation_info == NULL) {
+                    /* If not found in the channel's map, Look in the global RNTIs map */
+                    fp_crnti_allocation_info = (fp_crnti_allocation_info_t *)wmem_tree_lookup32(rrc_rach_urnti_crnti_map, c_rnti);
+                    if(fp_crnti_allocation_info != NULL) {
+                        /* If found in the global map, remove and insert to the channel's map*/
+                        wmem_tree_remove32(rrc_rach_urnti_crnti_map, c_rnti);
+                        if(fp_rach_channel_info) {
+                            wmem_tree_insert32(fp_rach_channel_info->crnti_to_urnti_map, c_rnti, (void *)fp_crnti_allocation_info);
+                        }
+                    }
+                }
+                break;
+            case CHANNEL_FACH_FDD:
+                /* In FACH: Look in the channel's RNTIs map */
+                if (umts_fp_conversation_info) {
+                    fp_fach_channel_info = (fp_fach_channel_info_t *)umts_fp_conversation_info->channel_specific_info;
+                    if(fp_fach_channel_info) {
+                        fp_crnti_allocation_info = (fp_crnti_allocation_info_t *)wmem_tree_lookup32(fp_fach_channel_info->crnti_to_urnti_map, c_rnti);
+                    }
+                }
+                break;
+        }
+        /* Choosing between resolved U-RNTI (if found) or the C-RNTI as UE-ID for RLC */
+        if(fp_crnti_allocation_info != NULL) {
+            /* Using U-RNTI */
+            rlcinf->urnti[fpinf->cur_tb] = fp_crnti_allocation_info->urnti;
+            /* Adding 'Resolved U-RNTI' related tree items*/
+            proto_item *temp;
+            proto_tree *resolved_urnti_tree;
+            temp = proto_tree_add_uint(tree, hf_mac_resolved_urnti, tvb, 0, 0, fp_crnti_allocation_info->urnti);
+            PROTO_ITEM_SET_GENERATED(temp);
+            resolved_urnti_tree = proto_item_add_subtree(temp, ett_mac_resolved_urnti);
+            temp = proto_tree_add_uint(resolved_urnti_tree , hf_mac_crnti_urnti_match_frame, tvb, 0, 0, fp_crnti_allocation_info->alloc_frame_number);
+            PROTO_ITEM_SET_GENERATED(temp);
+        }
+        else {
+            /* Using C-RNTI */
+            rlcinf->urnti[fpinf->cur_tb] = c_rnti;
+        }
         bitoffs += 16;
     }
 
@@ -1311,7 +1375,8 @@ proto_register_umts_mac(void)
         &ett_mac_edch,
         &ett_mac_hsdsch,
         &ett_mac_edch_type2,
-        &ett_mac_edch_type2_sdu
+        &ett_mac_edch_type2_sdu,
+        &ett_mac_resolved_urnti
     };
     /** XX: Looks like some duplicate filter names ?? **/
     /** XX: May be OK: See doc/README.developer       **/
@@ -1340,6 +1405,18 @@ proto_register_umts_mac(void)
           { "U-RNTI (UEID)", "mac.ueid",
             FT_UINT32, BASE_HEX, NULL, 0x0, NULL, HFILL }
         },
+        { &hf_mac_resolved_urnti,
+          { "Resolved U-RNTI", "mac.resolved_urnti",
+            FT_UINT32, BASE_HEX, NULL, 0x0,
+            "The U-RNTI of the UE which is using the C-RNTI seen in this frame",
+            HFILL }
+        },
+        { &hf_mac_crnti_urnti_match_frame,
+          { "C-RNTI Allocation Frame", "mac.crnti_urnti_match_frame",
+            FT_FRAMENUM, BASE_NONE, NULL, 0x0,
+            "The frame number where the C-RNTI was allocated for the UE",
+            HFILL }
+        },
         { &hf_mac_channel,
           { "Logical Channel Type", "mac.logical_channel",
             FT_UINT16, BASE_DEC, VALS(mac_logical_channel_vals), 0, NULL, HFILL }