gbproxy: Keep tlli_info after detach

Currently a tlli_info entry is deleted when the TLLI gets invalidated
by a Detach message.

This patch introduces the possibility to keep tlli_info entries in
the list. Those entries then have cleared TLLI fields, are marked as
de-registered, and can only be retrieved by a message containing an
IMSI or a P-TMSI.

The following VTY configuration commands are added to the gbproxy
node:
  - tlli-list keep-mode never : Don't keep the entries (default)
  - tlli-list keep-mode re-attach : Only keep them, when a Detach
    message with re-attach required has been received
  - tlli-list keep-mode identified : Only keep entries which are
    associated with an IMSI
  - tlli-list keep-mode always : Keep all entries

Note that at least one of max-length or max-age should be set when
this feature is used to limit the number of entries.

Sponsored-by: On-Waves ehf

1 files changed, 10 insertions, 0 deletions

diff --git a/openbsc/include/openbsc/gb_proxy.h b/openbsc/include/openbsc/gb_proxy.h
index 4a20bfb50..d9731a729 100644
--- a/openbsc/include/openbsc/gb_proxy.h
+++ b/openbsc/include/openbsc/gb_proxy.h
@@ -50,6 +50,13 @@ enum gbproxy_peer_ctr {
 	GBPROX_PEER_CTR_TLLI_CACHE_SIZE,
 };
 
+enum gbproxy_keep_mode {
+	GBPROX_KEEP_NEVER,
+	GBPROX_KEEP_REATTACH,
+	GBPROX_KEEP_IDENTIFIED,
+	GBPROX_KEEP_ALWAYS,
+};
+
 struct gbproxy_config {
 	/* parsed from config file */
 	uint16_t nsip_sgsn_nsei;
@@ -77,6 +84,7 @@ struct gbproxy_config {
 	int acquire_imsi;
 	int route_to_sgsn2;
 	uint16_t nsip_sgsn2_nsei;
+	enum gbproxy_keep_mode keep_tlli_infos;
 
 	/* IMSI checking/matching */
 	int check_imsi;
@@ -141,6 +149,8 @@ struct gbproxy_tlli_info {
 	struct llist_head stored_msgs;
 	int imsi_acq_retries;
 
+	int is_deregistered;
+
 	int enable_patching;
 };