neels has uploaded this change for review. ( https://gerrit.osmocom.org/c/osmo-hnbgw/+/34974?usp=email )
Change subject: allow second CS RAB Assignment Request ......................................................................
allow second CS RAB Assignment Request
In the field, we've encountered a so far unsupported scenario: after a RAB Assignment Request and Response have successfully set up an RTP stream, the CN sends *another* RAB Assignment Request to modify some SDU parameters, omitting the transportLayerInformation IE (not modifying the RTP address).
Detect a secondary RAB Assignment Request, and just forward it as-is: the hNodeB is interested in the RAB configuration, osmo-hnbgw just needs the RTP info, which is not even present in this use case.
Do not (yet?) support modifying the RTP address/port.
Related: osmo-ttcn3-hacks Iadaba0e5e82ad6d163ad509904ede213e2462d5c Related: SYS#6624 Change-Id: I25bf19981cd75a87a7ceb3382dae1ec626ae475c --- M src/osmo-hnbgw/mgw_fsm.c 1 file changed, 79 insertions(+), 0 deletions(-)
git pull ssh://gerrit.osmocom.org:29418/osmo-hnbgw refs/changes/74/34974/1
diff --git a/src/osmo-hnbgw/mgw_fsm.c b/src/osmo-hnbgw/mgw_fsm.c index ddab0b5..3bbd8c6 100644 --- a/src/osmo-hnbgw/mgw_fsm.c +++ b/src/osmo-hnbgw/mgw_fsm.c @@ -683,6 +683,47 @@ return 0; }
+static bool is_rab_ass_without_tli(struct hnbgw_context_map *map, ranap_message *message) +{ + RANAP_RAB_AssignmentRequestIEs_t *ies; + RANAP_ProtocolIE_ContainerPair_t *protocol_ie_container_pair; + RANAP_ProtocolIE_FieldPair_t *protocol_ie_field_pair; + RANAP_RAB_SetupOrModifyItemFirst_t _rab_setup_or_modify_item_first = { 0 }; + RANAP_RAB_SetupOrModifyItemFirst_t *rab_setup_or_modify_item_first = &_rab_setup_or_modify_item_first; + int rc; + bool ret; + + ies = &message->msg.raB_AssignmentRequestIEs; + + if (!(ies->presenceMask & RAB_ASSIGNMENTREQUESTIES_RANAP_RAB_SETUPORMODIFYLIST_PRESENT)) + return false; + + /* Detect the end of the list */ + if (ies->raB_SetupOrModifyList.list.count < 1) + return false; + + protocol_ie_container_pair = ies->raB_SetupOrModifyList.list.array[0]; + protocol_ie_field_pair = protocol_ie_container_pair->list.array[0]; + + if (!protocol_ie_field_pair) + return false; + + if (protocol_ie_field_pair->id != RANAP_ProtocolIE_ID_id_RAB_SetupOrModifyItem) { + RANAP_DEBUG + ("Decoding failed, the protocol IE field-pair is not of type RANAP RAB setup-or-modify-item!\n"); + return false; + } + + rc = ranap_decode_rab_setupormodifyitemfirst(rab_setup_or_modify_item_first, + &protocol_ie_field_pair->firstValue); + if (rc < 0) + return false; + + ret = rab_setup_or_modify_item_first->transportLayerInformation == NULL; + ASN_STRUCT_FREE_CONTENTS_ONLY(asn_DEF_RANAP_RAB_SetupOrModifyItemFirst, rab_setup_or_modify_item_first); + return ret; +} + /* Check if the message contains a RAB-ReleaseItem that matches the RAB-ID that is managed by the given context map */ static bool is_our_rab_release(struct hnbgw_context_map *map, ranap_message *message) { @@ -721,6 +762,14 @@ initialized = true; }
+ /* After a normal RAB Assignment, another RAB Assigment may follow, modifying some RAB parameters. This second + * RAB Assignment may omit transportLayerInformation (remains unchanged). Simply forward this to RUA, without + * the need to adjust anything here. Allow this only when there already is an mgw_fsm with proper address. */ + if (map->mgw_fi && is_rab_ass_without_tli(map, message)) { + LOG_MAP(map, DCN, LOGL_INFO, "Rx secondary RAB Assignment Request, forwarding as-is\n"); + return map_rua_dispatch(map, MAP_RUA_EV_TX_DIRECT_TRANSFER, ranap_msg); + } + /* The RTP stream negotiation usually begins with a RAB-AssignmentRequest and ends with an IU-Release, however * it may also be that the MSC decides to release the RAB with a dedicated RAB-AssignmentRequest that contains * a ReleaseList. In this case an FSM will already be present. */ @@ -791,6 +840,13 @@ return -1; }
+ if (map->mgw_fi->state == MGW_ST_ESTABLISHED) { + /* This is a response to a second RAB Assignment Request, which only modified some RAB config on top of + * an earlier RAB Assignment. Just forward the response as-is, we already have our MGW set up and need + * no info from it. (i.e. we don't support modifying the RTP address.) */ + return map_sccp_dispatch(map, MAP_SCCP_EV_TX_DATA_REQUEST, ranap_msg); + } + mgw_fsm_priv = map->mgw_fi->priv;
talloc_steal(mgw_fsm_priv, ranap_msg);
-
neels