gprs_gmm: introduce a GMM Attach Request FSM

The old GMM Attach Request handling used a recursive function
which can not handle certain states and is quite complex and hard to
extend.

The new FSM handles such request in a FSM and can be called multiple
times.

Change-Id: I58b9c17be9776a03bb2a5b21e99135cfefc8c912

1 files changed, 37 insertions, 0 deletions

diff --git a/include/osmocom/sgsn/gprs_gmm_attach.h b/include/osmocom/sgsn/gprs_gmm_attach.h
new file mode 100644
index 000000000..22fbd6f9d
--- /dev/null
+++ b/include/osmocom/sgsn/gprs_gmm_attach.h
@@ -0,0 +1,37 @@
+#ifndef GPRS_GMM_ATTACH_H
+#define GPRS_GMM_ATTACH_H
+
+#include <osmocom/core/fsm.h>
+
+struct sgsn_mm_ctx;
+
+enum gmm_attach_req_fsm_states {
+	ST_INIT,
+	ST_IDENTIY,
+	ST_RETRIEVE_AUTH,
+	ST_AUTH,
+	ST_ASK_VLR,
+	ST_ACCEPT,
+	ST_REJECT
+};
+
+enum gmm_attach_req_fsm_events {
+	E_ATTACH_REQ_RECV,
+	E_IDEN_RESP_RECV,
+	E_AUTH_RESP_RECV_SUCCESS,
+	E_AUTH_RESP_RECV_RESYNC,
+	E_ATTACH_ACCEPTED,
+	E_ATTACH_ACCEPT_SENT,
+	E_ATTACH_COMPLETE_RECV,
+	E_REJECT,
+	E_VLR_ANSWERED,
+};
+
+#define GMM_DISCARD_MS_WITHOUT_REJECT -1
+
+extern const struct value_string gmm_attach_req_fsm_event_names[];
+extern struct osmo_fsm gmm_attach_req_fsm;
+
+void gmm_att_req_free(struct sgsn_mm_ctx *mm);
+
+#endif // GPRS_GMM_ATTACH_H