[M] Change in ...osmo-s1gw[master]: sctp_proxy: maintain opaque state for s1ap_proxy

10 Jul 2024

fixeria has uploaded this change for review. ( https://gerrit.osmocom.org/c/erlang/osmo-s1gw/+/37462?usp=email )
Change subject: sctp_proxy: maintain opaque state for s1ap_proxy
......................................................................
sctp_proxy: maintain opaque state for s1ap_proxy
Change-Id: I6ea8479c1a66bca330a7d4030cc7cdf55a76b12c
---
M src/s1ap_proxy.erl
M src/sctp_proxy.erl
2 files changed, 131 insertions(+), 91 deletions(-)
git pull ssh://gerrit.osmocom.org:29418/erlang/osmo-s1gw refs/changes/62/37462/1

diff --git a/src/s1ap_proxy.erl b/src/s1ap_proxy.erl
index 579df40..eaa7dfd 100644
--- a/src/s1ap_proxy.erl
+++ b/src/s1ap_proxy.erl
@@ -34,7 +34,9 @@
-module(s1ap_proxy).
--export([handle_pdu/1,
+-export([init/0,
+         deinit/1,
+         handle_pdu/2,
          encode_pdu/1,
          decode_pdu/1]).
@@ -45,20 +47,37 @@
 -include("S1AP-Containers.hrl").
 -include("S1AP-Constants.hrl").
+
+-record(proxy_state, { }).
+
+-type proxy_state() :: #proxy_state{}.
+
 %% ------------------------------------------------------------------
 %% public API
 %% ------------------------------------------------------------------
+%% Initialize per-connection data
+-spec init() -> proxy_state().
+init() ->
+    #proxy_state{}.
+
+
+%% De-initialize per-connection data
+-spec deinit(proxy_state()) -> ok.
+deinit(_S) ->
+    ok.
+
+
 %% Process an S1AP PDU
--spec handle_pdu(binary()) -> binary().
-handle_pdu(Data) when is_binary(Data) ->
+-spec handle_pdu(binary(), proxy_state()) -> {binary(), proxy_state()}.
+handle_pdu(Data, S) when is_binary(Data) ->
     case decode_pdu(Data) of
         {ok, Pdu} ->
             ?LOG_INFO("S1AP PDU: ~p", [Pdu]),
-            handle_pdu(Data, Pdu);
+            handle_pdu(Data, Pdu, S);
         {error, {asn1, Error}} ->
             ?LOG_ERROR("S1AP PDU decoding failed: ~p", [Error]),
-            Data
+            {Data, S}
     end.
@@ -80,73 +99,73 @@
     'S1AP-PDU-Descriptions':decode('S1AP-PDU', Data).
-%% Helper function for handle_pdu/2.
+%% Helper function for handle_pdu/3.
 %% Attempt to encode a new (modified) S1AP PDU,
 %% return a new binary() on success or Data on error.
-handle_pdu_new(Data, NewPdu) ->
+handle_pdu_new(Data, NewPdu, S) ->
     case encode_pdu(NewPdu) of
         {ok, NewData} ->
-            NewData;
+            {NewData, S};
         {error, {asn1, Error}} ->
             ?LOG_ERROR("S1AP PDU encoding failed: ~p", [Error]),
-            Data
+            {Data, S}
     end.
%% 9.1.3.1 E-RAB SETUP REQUEST
 handle_pdu(Data, {Outcome = initiatingMessage,
                   #'InitiatingMessage'{procedureCode = ?'id-E-RABSetup',
-                                       value = Content} = Pdu}) ->
+                                       value = Content} = Pdu}, S0) ->
     ?LOG_DEBUG("Patching E-RAB SETUP REQUEST"),
-    IEs = handle_ies(Content#'E-RABSetupRequest'.protocolIEs,
-                     ?'id-E-RABToBeSetupListBearerSUReq'),
+    {IEs, S1} = handle_ies(Content#'E-RABSetupRequest'.protocolIEs,
+                           ?'id-E-RABToBeSetupListBearerSUReq', S0),
     NewContent = Content#'E-RABSetupRequest'{protocolIEs = IEs},
-    handle_pdu_new(Data, {Outcome, Pdu#'InitiatingMessage'{value = NewContent}});
+    handle_pdu_new(Data, {Outcome, Pdu#'InitiatingMessage'{value = NewContent}}, S1);
%% 9.1.3.2 E-RAB SETUP RESPONSE
 handle_pdu(Data, {Outcome = successfulOutcome,
                   #'SuccessfulOutcome'{procedureCode = ?'id-E-RABSetup',
-                                       value = Content} = Pdu}) ->
+                                       value = Content} = Pdu}, S0) ->
     ?LOG_DEBUG("Patching E-RAB SETUP RESPONSE"),
-    IEs = handle_ies(Content#'E-RABSetupResponse'.protocolIEs,
-                     ?'id-E-RABSetupListBearerSURes'),
+    {IEs, S1} = handle_ies(Content#'E-RABSetupResponse'.protocolIEs,
+                           ?'id-E-RABSetupListBearerSURes', S0),
     NewContent = Content#'E-RABSetupResponse'{protocolIEs = IEs},
-    handle_pdu_new(Data, {Outcome, Pdu#'SuccessfulOutcome'{value = NewContent}});
+    handle_pdu_new(Data, {Outcome, Pdu#'SuccessfulOutcome'{value = NewContent}}, S1);
%% TODO: 9.1.3.3 E-RAB MODIFY REQUEST / (Optional) Transport Information
%% 9.1.3.8 E-RAB MODIFICATION INDICATION
 handle_pdu(Data, {Outcome = initiatingMessage,
                   #'InitiatingMessage'{procedureCode = ?'id-E-RABModificationIndication',
-                                       value = Content} = Pdu}) ->
+                                       value = Content} = Pdu}, S0) ->
     ?LOG_DEBUG("Patching E-RAB MODIFICATION INDICATION"),
     IEs = Content#'E-RABModificationIndication'.protocolIEs,
     %% E-RAB to be Modified List
-    IEs1 = handle_ies(IEs, ?'id-E-RABToBeModifiedListBearerModInd'),
+    {IEs1, S1} = handle_ies(IEs, ?'id-E-RABToBeModifiedListBearerModInd', S0),
     %% E-RAB not to be Modified List
-    IEs2 = handle_ies(IEs1, ?'id-E-RABNotToBeModifiedListBearerModInd'),
+    {IEs2, S2} = handle_ies(IEs1, ?'id-E-RABNotToBeModifiedListBearerModInd', S1),
     NewContent = Content#'E-RABModificationIndication'{protocolIEs = IEs2},
-    handle_pdu_new(Data, {Outcome, Pdu#'InitiatingMessage'{value = NewContent}});
+    handle_pdu_new(Data, {Outcome, Pdu#'InitiatingMessage'{value = NewContent}}, S2);
%% 9.1.4.1 INITIAL CONTEXT SETUP REQUEST
 handle_pdu(Data, {Outcome = initiatingMessage,
                   #'InitiatingMessage'{procedureCode = ?'id-InitialContextSetup',
-                                       value = Content} = Pdu}) ->
+                                       value = Content} = Pdu}, S0) ->
     ?LOG_DEBUG("Patching INITIAL CONTEXT SETUP REQUEST"),
-    IEs = handle_ies(Content#'InitialContextSetupRequest'.protocolIEs,
-                     ?'id-E-RABToBeSetupListCtxtSUReq'),
+    {IEs, S1} = handle_ies(Content#'InitialContextSetupRequest'.protocolIEs,
+                           ?'id-E-RABToBeSetupListCtxtSUReq', S0),
     NewContent = Content#'InitialContextSetupRequest'{protocolIEs = IEs},
-    handle_pdu_new(Data, {Outcome, Pdu#'InitiatingMessage'{value = NewContent}});
+    handle_pdu_new(Data, {Outcome, Pdu#'InitiatingMessage'{value = NewContent}}, S1);
%% 9.1.4.3 INITIAL CONTEXT SETUP RESPONSE
 handle_pdu(Data, {Outcome = successfulOutcome,
                   #'SuccessfulOutcome'{procedureCode = ?'id-InitialContextSetup',
-                                       value = Content} = Pdu}) ->
+                                       value = Content} = Pdu}, S0) ->
     ?LOG_DEBUG("Patching INITIAL CONTEXT SETUP RESPONSE"),
-    IEs = handle_ies(Content#'InitialContextSetupResponse'.protocolIEs,
-                     ?'id-E-RABSetupListCtxtSURes'),
+    {IEs, S1} = handle_ies(Content#'InitialContextSetupResponse'.protocolIEs,
+                           ?'id-E-RABSetupListCtxtSURes', S0),
     NewContent = Content#'InitialContextSetupResponse'{protocolIEs = IEs},
-    handle_pdu_new(Data, {Outcome, Pdu#'SuccessfulOutcome'{value = NewContent}});
+    handle_pdu_new(Data, {Outcome, Pdu#'SuccessfulOutcome'{value = NewContent}}, S1);
%% TODO: 9.1.5.2 HANDOVER COMMAND :: (O) UL/DL Transport Layer Address
 %% TODO: 9.1.5.4 HANDOVER REQUEST :: (M) Transport Layer Address
@@ -156,107 +175,108 @@
 %% TODO: 9.1.5.9 PATH SWITCH REQUEST ACKNOWLEDGE :: (M) Transport Layer Address
%% Proxy all other messages unmodified
-handle_pdu(Data, _Pdu) ->
-    Data.
+handle_pdu(Data, _Pdu, S) ->
+    {Data, S}.
%% Handle a single IE (Information Element)
--spec handle_ie(tuple()) -> tuple().
+-spec handle_ie(tuple(), proxy_state()) -> {tuple(), proxy_state()}.
%% E-RAB SETUP REQUEST related IEs
 handle_ie(#'ProtocolIE-Field'{id = ?'id-E-RABToBeSetupListBearerSUReq',
-                              value = Content}) ->
+                              value = Content}, S) ->
     %% This IE contains a list of BearerSUReq, so patch inner IEs
-    handle_ies(Content, ?'id-E-RABToBeSetupItemBearerSUReq');
+    handle_ies(Content, ?'id-E-RABToBeSetupItemBearerSUReq', S);
handle_ie(#'ProtocolIE-Field'{id = ?'id-E-RABToBeSetupItemBearerSUReq',
-                              value = Content}) ->
+                              value = Content}, S) ->
     %% eNB -> MME direction: we pass our MME facing local address
     TLA = transp_layer_addr(mme_loc_addr),
-    Content#'E-RABToBeSetupItemBearerSUReq'{transportLayerAddress = TLA};
+    {Content#'E-RABToBeSetupItemBearerSUReq'{transportLayerAddress = TLA}, S};
%% E-RAB SETUP RESPONSE related IEs
 handle_ie(#'ProtocolIE-Field'{id = ?'id-E-RABSetupListBearerSURes',
-                              value = Content}) ->
+                              value = Content}, S) ->
     %% This IE contains a list of BearerSURes, so patch inner IEs
-    handle_ies(Content, ?'id-E-RABSetupItemBearerSURes');
+    handle_ies(Content, ?'id-E-RABSetupItemBearerSURes', S);
handle_ie(#'ProtocolIE-Field'{id = ?'id-E-RABSetupItemBearerSURes',
-                              value = Content}) ->
+                              value = Content}, S) ->
     %% MME -> eNB direction: we pass our eNB facing local address
     TLA = transp_layer_addr(s1gw_bind_addr),
-    Content#'E-RABSetupItemBearerSURes'{transportLayerAddress = TLA};
+    {Content#'E-RABSetupItemBearerSURes'{transportLayerAddress = TLA}, S};
%% E-RAB MODIFICATION INDICATION related IEs
 handle_ie(#'ProtocolIE-Field'{id = ?'id-E-RABToBeModifiedListBearerModInd',
-                              value = Content}) ->
+                              value = Content}, S) ->
     %% This IE contains a list of BearerModInd, so patch inner IEs
-    handle_ies(Content, ?'id-E-RABToBeModifiedItemBearerModInd');
+    handle_ies(Content, ?'id-E-RABToBeModifiedItemBearerModInd', S);
handle_ie(#'ProtocolIE-Field'{id = ?'id-E-RABToBeModifiedItemBearerModInd',
-                              value = Content}) ->
+                              value = Content}, S) ->
     %% eNB -> MME direction: we pass our MME facing local address
     TLA = transp_layer_addr(mme_loc_addr),
-    Content#'E-RABToBeModifiedItemBearerModInd'{transportLayerAddress = TLA};
+    {Content#'E-RABToBeModifiedItemBearerModInd'{transportLayerAddress = TLA}, S};
handle_ie(#'ProtocolIE-Field'{id = ?'id-E-RABNotToBeModifiedListBearerModInd',
-                              value = Content}) ->
+                              value = Content}, S) ->
     %% This IE contains a list of BearerModInd, so patch inner IEs
-    handle_ies(Content, ?'id-E-RABNotToBeModifiedItemBearerModInd');
+    handle_ies(Content, ?'id-E-RABNotToBeModifiedItemBearerModInd', S);
handle_ie(#'ProtocolIE-Field'{id = ?'id-E-RABNotToBeModifiedItemBearerModInd',
-                              value = Content}) ->
+                              value = Content}, S) ->
     %% eNB -> MME direction: we pass our MME facing local address
     TLA = transp_layer_addr(mme_loc_addr),
-    Content#'E-RABNotToBeModifiedItemBearerModInd'{transportLayerAddress = TLA};
+    {Content#'E-RABNotToBeModifiedItemBearerModInd'{transportLayerAddress = TLA}, S};
%% INITIAL CONTEXT SETUP REQUEST related IEs
 handle_ie(#'ProtocolIE-Field'{id = ?'id-E-RABToBeSetupListCtxtSUReq',
-                              value = Content}) ->
+                              value = Content}, S) ->
     %% This IE contains a list of CtxtSUReq, so patch inner IEs
-    handle_ies(Content, ?'id-E-RABToBeSetupItemCtxtSUReq');
+    handle_ies(Content, ?'id-E-RABToBeSetupItemCtxtSUReq', S);
handle_ie(#'ProtocolIE-Field'{id = ?'id-E-RABToBeSetupItemCtxtSUReq',
-                              value = Content}) ->
+                              value = Content}, S) ->
     %% eNB -> MME direction: we pass our MME facing local address
     TLA = transp_layer_addr(mme_loc_addr),
-    Content#'E-RABToBeSetupItemCtxtSUReq'{transportLayerAddress = TLA};
+    {Content#'E-RABToBeSetupItemCtxtSUReq'{transportLayerAddress = TLA}, S};
%% INITIAL CONTEXT SETUP RESPONSE related IEs
 handle_ie(#'ProtocolIE-Field'{id = ?'id-E-RABSetupListCtxtSURes',
-                              value = Content}) ->
+                              value = Content}, S) ->
     %% This IE contains a list of CtxtSURes, so patch inner IEs
-    handle_ies(Content, ?'id-E-RABSetupItemCtxtSURes');
+    handle_ies(Content, ?'id-E-RABSetupItemCtxtSURes', S);
handle_ie(#'ProtocolIE-Field'{id = ?'id-E-RABSetupItemCtxtSURes',
-                              value = Content}) ->
+                              value = Content}, S) ->
     %% MME -> eNB direction: we pass our eNB facing local address
     TLA = transp_layer_addr(s1gw_bind_addr),
-    Content#'E-RABSetupItemCtxtSURes'{transportLayerAddress = TLA};
+    {Content#'E-RABSetupItemCtxtSURes'{transportLayerAddress = TLA}, S};
%% Catch-all variant, which should not be called normally
-handle_ie(#'ProtocolIE-Field'{value = Content} = IE) ->
+handle_ie(#'ProtocolIE-Field'{value = Content} = IE, S) ->
     ?LOG_ERROR("[BUG] Unhandled S1AP IE: ~p", [IE]),
-    Content.
+    {Content, S}.
%% Iterate over the given list of 'ProtocolIE-Field' IEs,
 %% calling function handle_ie/1 for IEs matching the given IEI.
--spec handle_ies(list(), integer()) -> list().
-handle_ies(IEs, IEI) ->
-    handle_ies([], IEs, IEI).
+-spec handle_ies(list(), integer(), proxy_state()) -> {list(), proxy_state()}.
+handle_ies(IEs, IEI, S) ->
+    handle_ies([], IEs, IEI, S).
-handle_ies(Acc, [IE | IEs], IEI) ->
+handle_ies(Acc, [IE | IEs], IEI, S0) ->
     case IE of
         #'ProtocolIE-Field'{id = IEI} ->
-            NewIE = IE#'ProtocolIE-Field'{value = handle_ie(IE)},
-            handle_ies([NewIE | Acc], IEs, IEI);
+            {Content, S1} = handle_ie(IE, S0),
+            NewIE = IE#'ProtocolIE-Field'{value = Content},
+            handle_ies([NewIE | Acc], IEs, IEI, S1);
         _ ->
-            handle_ies([IE | Acc], IEs, IEI)
+            handle_ies([IE | Acc], IEs, IEI, S0)
     end;
-handle_ies(Acc, [], _) ->
-    lists:reverse(Acc).
+handle_ies(Acc, [], _IEI, S) ->
+    {lists:reverse(Acc), S}.
%% GTP-U IP address (TransportLayerAddress) to be used while patching
diff --git a/src/sctp_proxy.erl b/src/sctp_proxy.erl
index ab147e6..148e00a 100644
--- a/src/sctp_proxy.erl
+++ b/src/sctp_proxy.erl
@@ -79,7 +79,8 @@
      #{enb_aid => Aid,
        mme_addr => MmeAddr,
        mme_port => MmePort,
-       tx_queue => []}}.
+       tx_queue => [],
+       priv => s1ap_proxy:init()}}.
callback_mode() ->
@@ -131,16 +132,16 @@
%% CONNECTED state
-connected(enter, OldState, S) ->
+connected(enter, OldState, S0) ->
     ?LOG_INFO("State change: ~p -> ~p", [OldState, ?FUNCTION_NAME]),
     %% Send pending eNB -> MME messages (if any)
-    ok = sctp_send_pending(S),
-    {keep_state, maps:remove(tx_queue, S)};
+    S1 = sctp_send_pending(S0),
+    {keep_state, S1};
%% Handle an eNB -> MME data forwarding request (forward)
-connected(cast, {send_data, Data}, S) ->
-    ok = sctp_send(S, Data),
-    {keep_state, S};
+connected(cast, {send_data, Data}, S0) ->
+    S1 = sctp_send(Data, S0),
+    {keep_state, S1};
%% Handle an #sctp_assoc_change event (MME connection state)
 connected(info, {sctp, _Socket, MmeAddr, MmePort,
@@ -158,11 +159,13 @@
%% Handle an #sctp_sndrcvinfo event (MME -> eNB data)
 connected(info, {sctp, _Socket, MmeAddr, MmePort,
-                 {[#sctp_sndrcvinfo{assoc_id = Aid}], Data}}, S) ->
+                 {[#sctp_sndrcvinfo{assoc_id = Aid}], Data}},
+          #{enb_aid := EnbAid, priv := Priv} = S) ->
     ?LOG_DEBUG("MME connection (id=~p, ~p:~p) -> eNB: ~p",
                [Aid, MmeAddr, MmePort, Data]),
-    sctp_server:send_data(maps:get(enb_aid, S), handle_pdu(Data)),
-    {keep_state, S};
+    {NewData, NewPriv} = handle_pdu(Data, Priv),
+    sctp_server:send_data(EnbAid, NewData),
+    {keep_state, S#{priv := NewPriv}};
%% Catch-all for other kinds of SCTP events
 connected(info, {sctp, _Socket, MmeAddr, MmePort,
@@ -185,7 +188,10 @@
 terminate(Reason, State, S) ->
     ?LOG_NOTICE("Terminating in state ~p, reason ~p", [State, Reason]),
     case S of
-        #{sock := Sock, mme_aid := Aid} ->
+        #{sock := Sock,
+          mme_aid := Aid,
+          priv := Priv} ->
+            s1ap_proxy:deinit(Priv),
             sctp_client:disconnect({Sock, Aid}),
             gen_sctp:close(Sock);
         #{sock := Sock} ->
@@ -199,31 +205,36 @@
 %% ------------------------------------------------------------------
%% A safe wrapper for s1ap_proxy:handle_pdu/1
--spec handle_pdu(binary()) -> binary().
-handle_pdu(Data) when is_binary(Data) ->
-    try s1ap_proxy:handle_pdu(Data) of
-        NewData -> NewData
+-spec handle_pdu(binary(), term()) -> {binary(), term()}.
+handle_pdu(Data, Priv) when is_binary(Data) ->
+    try s1ap_proxy:handle_pdu(Data, Priv) of
+        Result -> Result %% {NewData, NewPriv}
     catch
         Exception:Reason:StackTrace ->
             ?LOG_ERROR("An exception occurred: ~p, ~p, ~p", [Exception, Reason, StackTrace]),
-            Data %% proxy as-is
+            {Data, Priv} %% proxy as-is
     end.
%% Send a single message to the MME
-sctp_send(#{sock := Sock, mme_aid := Aid}, Data) ->
-    sctp_client:send_data({Sock, Aid}, handle_pdu(Data)).
+sctp_send(Data,
+          #{sock := Sock,
+            mme_aid := Aid,
+            priv := Priv} = S) ->
+    {NewData, NewPriv} = handle_pdu(Data, Priv),
+    ok = sctp_client:send_data({Sock, Aid}, NewData),
+    S#{priv := NewPriv}.
%% Send pending messages to the MME
 sctp_send_pending(#{tx_queue := Pending} = S) ->
-    sctp_send_pending(S, lists:reverse(Pending)).
+    sctp_send_pending(lists:reverse(Pending), S).
-sctp_send_pending(S, [Data | Pending]) ->
-    sctp_send(S, Data),
-    sctp_send_pending(S, Pending);
+sctp_send_pending([Data | Pending], S0) ->
+    S1 = sctp_send(Data, S0),
+    sctp_send_pending(Pending, S1);
-sctp_send_pending(_S, []) ->
-    ok.
+sctp_send_pending([], S) ->
+    S#{tx_queue := []}.
%% vim:set ts=4 sw=4 et:
-- 
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Gerrit-Project: erlang/osmo-s1gw
Gerrit-Branch: master
Gerrit-Change-Id: I6ea8479c1a66bca330a7d4030cc7cdf55a76b12c
Gerrit-Change-Number: 37462
Gerrit-PatchSet: 1
Gerrit-Owner: fixeria vyanitskiy@sysmocom.de
Gerrit-MessageType: newchange



    

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[M] Change in ...osmo-s1gw[master]: sctp_proxy: maintain opaque state for s1ap_proxy