From 6d66a3ce55df5af86a7766178322a00d6c60026b Mon Sep 17 00:00:00 2001
From: Tobias Engel <tobias@ccc.de>
Date: Thu, 22 Mar 2012 15:09:54 +0100
Subject: Call Waiting SS

This patch adds the ability to activate, deactivate and interrogate the
Call Waiting SS (GSM 04.83) from a mobile station using either the menu
or the MMI codes *43#, #43# and *#43# (see GSM 02.30).

struct gsm_subscriber now has a member active_cc_transactions which will
be increased/decreased in new_cc_state. A call to a subscriber will now
only proceed if active_cc_transactions is either 0, or CW has been
provisioned and activated for that subscriber, otherwise the caller will
receive a "busy" signal.
---
 openbsc/include/openbsc/gsm_subscriber.h |  1 +
 openbsc/src/libmsc/gsm_04_08.c           | 39 +++++++++++++++++++++++++++++---
 2 files changed, 37 insertions(+), 3 deletions(-)

diff --git a/openbsc/include/openbsc/gsm_subscriber.h b/openbsc/include/openbsc/gsm_subscriber.h
index 6cf85731b..995a1cf8b 100644
--- a/openbsc/include/openbsc/gsm_subscriber.h
+++ b/openbsc/include/openbsc/gsm_subscriber.h
@@ -48,6 +48,7 @@ struct gsm_subscriber {
 
 	/* for internal management */
 	int use_count;
+	int active_cc_transactions;
 	struct llist_head entry;
 
 	/* pending requests */
diff --git a/openbsc/src/libmsc/gsm_04_08.c b/openbsc/src/libmsc/gsm_04_08.c
index 0e18d0c1d..bb043f9ea 100644
--- a/openbsc/src/libmsc/gsm_04_08.c
+++ b/openbsc/src/libmsc/gsm_04_08.c
@@ -1173,9 +1173,19 @@ static void new_cc_state(struct gsm_trans *trans, int state)
 	if (state > 31 || state < 0)
 		return;
 
-	DEBUGP(DCC, "new state %s -> %s\n",
-		gsm48_cc_state_name(trans->cc.state),
-		gsm48_cc_state_name(state));
+	if (trans->subscr) {
+		if (state != GSM_CSTATE_NULL &&
+		    trans->cc.state == GSM_CSTATE_NULL)
+			trans->subscr->active_cc_transactions++;
+		else if(state == GSM_CSTATE_NULL &&
+			trans->cc.state != GSM_CSTATE_NULL)
+			trans->subscr->active_cc_transactions--;
+	}
+
+	DEBUGP(DCC, "new state %s -> %s, %d active transactions\n",
+	       gsm48_cc_state_name(trans->cc.state),
+	       gsm48_cc_state_name(state),
+	       trans->subscr->active_cc_transactions);
 
 	trans->cc.state = state;
 }
@@ -2945,6 +2955,29 @@ int mncc_tx_to_cc(struct gsm_network *net, int msg_type, void *arg)
 						GSM48_CAUSE_LOC_PRN_S_LU,
 						GSM48_CC_CAUSE_DEST_OOO);
 		}
+		/* If subscriber is "busy" */
+		if (subscr->active_cc_transactions) {
+			int rc;
+			uint8_t ss_status = 0;
+			rc = db_ss_interrogate_status(subscr,
+						      GSM0902_SS_CODE_CW,
+						      GSM0902_TS_CODE_TELEPHONY,
+						      &ss_status);
+			DEBUGP(DCC, "(bts - trx - ts - ti -- sub %s) "
+			       "Received '%s' from MNCC with "
+			       "busy subscriber %s, cw ss_status: %X\n",
+			       data->called.number, get_mncc_name(msg_type),
+			       data->called.number, ss_status);
+			if(rc < 0 || (ss_status != (GSM0902_SS_STATUS_P_BIT | 
+						    GSM0902_SS_STATUS_A_BIT))) {
+				subscr_put(subscr);
+				/* User busy */
+				return mncc_release_ind(net, NULL,
+							data->callref,
+							GSM48_CAUSE_LOC_USER,
+							GSM48_CC_CAUSE_USER_BUSY);
+			}
+		}
 		/* Create transaction */
 		trans = trans_alloc(subscr, GSM48_PDISC_CC, 0xff, data->callref);
 		if (!trans) {
-- 
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