[smf][sgwc] minor checks and error-handling fixes (#68)

src/sgwc/pfcp-path.c

@@ -182,7 +182,11 @@ static void sess_timeout(ogs_pfcp_xact_t *pfcp_xact, void *data)
     ogs_assert(sess);
 
     s11_xact = pfcp_xact->assoc_xact;
-    ogs_assert(s11_xact);
+
+    if (!s11_xact) {
+        ogs_error("sess_timeout: No s11 context");
+        return;
+    }
 
     switch (s11_xact->gtp_version) {
     case 1:

src/sgwc/s5c-handler.c

@@ -92,11 +92,15 @@ void sgwc_s5c_handle_create_session_response(
      ********************/
     ogs_assert(s5c_xact);
     s11_xact = s5c_xact->assoc_xact;
-    ogs_assert(s11_xact);
 
     rv = ogs_gtp_xact_commit(s5c_xact);
     ogs_expect(rv == OGS_OK);
 
+    if (!s11_xact) {
+        ogs_error("No associated s11_xact!");
+        return;
+    }
+
     /************************
      * Getting Cause Value
      ************************/

src/sgwc/sxa-handler.c

@@ -182,9 +182,14 @@ void sgwc_sxa_handle_session_establishment_response(
         return sgwc_sxa_handle_session_reestablishment(sess, pfcp_xact, pfcp_rsp);
     }
 
+    if (!recv_message) {
+        ogs_error("recv_message is nil! Aborting...");
+        ogs_pfcp_xact_commit(pfcp_xact);
+        return;
+    }
+
     ogs_assert(pfcp_xact);
     ogs_assert(pfcp_rsp);
-
     ogs_assert(recv_message);
 
     create_session_request = &recv_message->create_session_request;