Bluetooth: Add get_connections managment interface command

This patch adds a get_connections command to the management interface.
With this command userspace can get the current list of connected
devices. Typically this command would only be used once when enumerating
existing adapters. After that the connected and disconnected events are
used to track connections.
Signed-off-by: Johan Hedberg <johan.hedberg@nokia.com>
Signed-off-by: Gustavo F. Padovan <padovan@profusion.mobi>

include/net/bluetooth/mgmt.h

@@ -130,6 +130,16 @@ struct mgmt_rp_disconnect {
 	bdaddr_t bdaddr;
 } __packed;
 
+#define MGMT_OP_GET_CONNECTIONS		0x0010
+struct mgmt_cp_get_connections {
+	__le16 index;
+} __packed;
+struct mgmt_rp_get_connections {
+	__le16 index;
+	__le16 conn_count;
+	bdaddr_t conn[0];
+} __packed;
+
 #define MGMT_EV_CMD_COMPLETE		0x0001
 struct mgmt_ev_cmd_complete {
 	__le16 opcode;

net/bluetooth/mgmt.c

@@ -941,6 +941,75 @@ static int disconnect(struct sock *sk, unsigned char *data, u16 len)
 	return err;
 }
 
+static int get_connections(struct sock *sk, unsigned char *data, u16 len)
+{
+	struct sk_buff *skb;
+	struct mgmt_hdr *hdr;
+	struct mgmt_cp_get_connections *cp;
+	struct mgmt_ev_cmd_complete *ev;
+	struct mgmt_rp_get_connections *rp;
+	struct hci_dev *hdev;
+	struct list_head *p;
+	size_t body_len;
+	u16 dev_id, count;
+	int i, err;
+
+	BT_DBG("");
+
+	cp = (void *) data;
+	dev_id = get_unaligned_le16(&cp->index);
+
+	hdev = hci_dev_get(dev_id);
+	if (!hdev)
+		return cmd_status(sk, MGMT_OP_GET_CONNECTIONS, ENODEV);
+
+	hci_dev_lock_bh(hdev);
+
+	count = 0;
+	list_for_each(p, &hdev->conn_hash.list) {
+		count++;
+	}
+
+	body_len = sizeof(*ev) + sizeof(*rp) + (count * sizeof(bdaddr_t));
+	skb = alloc_skb(sizeof(*hdr) + body_len, GFP_ATOMIC);
+	if (!skb) {
+		err = -ENOMEM;
+		goto unlock;
+	}
+
+	hdr = (void *) skb_put(skb, sizeof(*hdr));
+	hdr->opcode = cpu_to_le16(MGMT_EV_CMD_COMPLETE);
+	hdr->len = cpu_to_le16(body_len);
+
+	ev = (void *) skb_put(skb, sizeof(*ev));
+	put_unaligned_le16(MGMT_OP_GET_CONNECTIONS, &ev->opcode);
+
+	rp = (void *) skb_put(skb, sizeof(*rp) + (count * sizeof(bdaddr_t)));
+	put_unaligned_le16(dev_id, &rp->index);
+	put_unaligned_le16(count, &rp->conn_count);
+
+	read_lock(&hci_dev_list_lock);
+
+	i = 0;
+	list_for_each(p, &hdev->conn_hash.list) {
+		struct hci_conn *c = list_entry(p, struct hci_conn, list);
+
+		bacpy(&rp->conn[i++], &c->dst);
+	}
+
+	read_unlock(&hci_dev_list_lock);
+
+	if (sock_queue_rcv_skb(sk, skb) < 0)
+		kfree_skb(skb);
+
+	err = 0;
+
+unlock:
+	hci_dev_unlock_bh(hdev);
+	hci_dev_put(hdev);
+	return err;
+}
+
 int mgmt_control(struct sock *sk, struct msghdr *msg, size_t msglen)
 {
 	unsigned char *buf;
@@ -1014,6 +1083,9 @@ int mgmt_control(struct sock *sk, struct msghdr *msg, size_t msglen)
 	case MGMT_OP_DISCONNECT:
 		err = disconnect(sk, buf + sizeof(*hdr), len);
 		break;
+	case MGMT_OP_GET_CONNECTIONS:
+		err = get_connections(sk, buf + sizeof(*hdr), len);
+		break;
 	default:
 		BT_DBG("Unknown op %u", opcode);
 		err = cmd_status(sk, opcode, 0x01);