From 70b5556b0964a15eaad6c40a3c0df5447a8e5485 Mon Sep 17 00:00:00 2001
From: Trond Einar Snekvik <Trond.Einar.Snekvik@nordicsemi.no>
Date: Mon, 30 Sep 2019 13:27:02 +0200
Subject: [PATCH] Bluetooth: Mesh: Expose app key get

Provides a utility function for getting an application key given a
subnet and an app ID. Primary use-case in friendship re-encryption.

Signed-off-by: Trond Einar Snekvik <Trond.Einar.Snekvik@nordicsemi.no>
---
 subsys/bluetooth/mesh/transport.c | 57 ++++++++++++++++++++-----------
 subsys/bluetooth/mesh/transport.h |  3 ++
 2 files changed, 41 insertions(+), 19 deletions(-)

diff --git a/subsys/bluetooth/mesh/transport.c b/subsys/bluetooth/mesh/transport.c
index 3dee0011750..6e6cad23c84 100644
--- a/subsys/bluetooth/mesh/transport.c
+++ b/subsys/bluetooth/mesh/transport.c
@@ -485,6 +485,7 @@ int bt_mesh_trans_send(struct bt_mesh_net_tx *tx, struct net_buf_simple *msg,
 {
 	const u8_t *key;
 	u8_t *ad;
+	u8_t aid;
 	int err;
 
 	if (net_buf_simple_tailroom(msg) < 4) {
@@ -500,27 +501,14 @@ int bt_mesh_trans_send(struct bt_mesh_net_tx *tx, struct net_buf_simple *msg,
 	       tx->ctx->app_idx, tx->ctx->addr);
 	BT_DBG("len %u: %s", msg->len, bt_hex(msg->data, msg->len));
 
-	if (tx->ctx->app_idx == BT_MESH_KEY_DEV) {
-		key = bt_mesh.dev_key;
-		tx->aid = 0U;
-	} else {
-		struct bt_mesh_app_key *app_key;
-
-		app_key = bt_mesh_app_key_find(tx->ctx->app_idx);
-		if (!app_key) {
-			return -EINVAL;
-		}
-
-		if (tx->sub->kr_phase == BT_MESH_KR_PHASE_2 &&
-		    app_key->updated) {
-			key = app_key->keys[1].val;
-			tx->aid = app_key->keys[1].id;
-		} else {
-			key = app_key->keys[0].val;
-			tx->aid = app_key->keys[0].id;
-		}
+	err = bt_mesh_app_key_get(tx->sub, tx->ctx->app_idx, &key,
+				  &aid);
+	if (err) {
+		return err;
 	}
 
+	tx->aid = aid;
+
 	if (!tx->ctx->send_rel || net_buf_simple_tailroom(msg) < 8) {
 		tx->aszmic = 0U;
 	} else {
@@ -1600,3 +1588,34 @@ void bt_mesh_heartbeat_send(void)
 	bt_mesh_ctl_send(&tx, TRANS_CTL_OP_HEARTBEAT, &hb, sizeof(hb),
 			 NULL, NULL, NULL);
 }
+
+int bt_mesh_app_key_get(const struct bt_mesh_subnet *subnet, u16_t app_idx,
+			const u8_t **key, u8_t *aid)
+{
+	struct bt_mesh_app_key *app_key;
+
+	if (app_idx == BT_MESH_KEY_DEV) {
+		*aid = 0;
+		*key = bt_mesh.dev_key;
+		return 0;
+	}
+
+	if (!subnet) {
+		return -EINVAL;
+	}
+
+	app_key = bt_mesh_app_key_find(app_idx);
+	if (!app_key) {
+		return -ENOENT;
+	}
+
+	if (subnet->kr_phase == BT_MESH_KR_PHASE_2 && app_key->updated) {
+		*key = app_key->keys[1].val;
+		*aid = app_key->keys[1].id;
+	} else {
+		*key = app_key->keys[0].val;
+		*aid = app_key->keys[0].id;
+	}
+
+	return 0;
+}
diff --git a/subsys/bluetooth/mesh/transport.h b/subsys/bluetooth/mesh/transport.h
index 68b886a97b3..1c787029c22 100644
--- a/subsys/bluetooth/mesh/transport.h
+++ b/subsys/bluetooth/mesh/transport.h
@@ -97,3 +97,6 @@ void bt_mesh_trans_init(void);
 void bt_mesh_rpl_clear(void);
 
 void bt_mesh_heartbeat_send(void);
+
+int bt_mesh_app_key_get(const struct bt_mesh_subnet *subnet, u16_t app_idx,
+			const u8_t **key, u8_t *aid);