fixeria has uploaded this change for review.

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s1ap_proxy: catch exceptions in handle_pdu/2

We do have a try-catch block in handle_pdu_bin/2 that does catch
exceptions happening in decode_pdu/1, but does not catch anything
else.  For instance, if something goes wrong in handle_pdu/2,
the whole process will be terminated, among with all the linked
E-RAB FSMs.  This should definitely be avoided.

Change-Id: Ib1e6674f5b85557866c7beaea710ea903e4eeaca
---
M src/s1ap_proxy.erl
1 file changed, 7 insertions(+), 1 deletion(-)

git pull ssh://gerrit.osmocom.org:29418/erlang/osmo-s1gw refs/changes/56/39556/1

diff --git a/src/s1ap_proxy.erl b/src/s1ap_proxy.erl
index 56e5dee..0cef81e 100644
--- a/src/s1ap_proxy.erl
+++ b/src/s1ap_proxy.erl
@@ -215,7 +215,7 @@
     try decode_pdu(OrigData) of
         {ok, PDU} ->
             ?LOG_DEBUG("Rx S1AP PDU: ~p", [PDU]),
-            case handle_pdu(PDU, S0) of
+            try handle_pdu(PDU, S0) of
                 {{Action, NewPDU}, S1} ->
                     {ok, NewData} = encode_pdu(NewPDU),
                     ?LOG_DEBUG("Tx (~p) S1AP PDU: ~p", [Action, NewPDU]),
@@ -232,6 +232,12 @@
                     s1gw_metrics:ctr_inc(?S1GW_CTR_S1AP_PROXY_OUT_PKT_FWD_ALL),
                     s1gw_metrics:ctr_inc(?S1GW_CTR_S1AP_PROXY_OUT_PKT_FWD_UNMODIFIED),
                     {{forward, OrigData}, S1}
+            catch
+                Exception:Reason:StackTrace ->
+                    ?LOG_ERROR("An exception occurred: ~p, ~p, ~p", [Exception, Reason, StackTrace]),
+                    s1gw_metrics:ctr_inc(?S1GW_CTR_S1AP_PROXY_EXCEPTION),
+                    s1gw_metrics:ctr_inc(?S1GW_CTR_S1AP_PROXY_OUT_PKT_FWD_UNMODIFIED),
+                    {{forward, OrigData}, S0} %% XXX: proxy as-is or drop?
             end;
         {error, {asn1, Error}} ->
             ?LOG_ERROR("S1AP PDU decoding failed: ~p", [Error]),

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