[RFCv7 09/23] Bluetooth: A2MP: Process A2MP Discover Request

[Andrei Emeltchenko <Andrei.Emeltchenko.news@gmail.com>]

From: Andrei Emeltchenko <andrei.emeltchenko@intel.com>

Adds helper functions to count HCI devs and process A2MP Discover
Request, code makes sure that first controller in the list is
BREDR one. Trace is shown below:

...
> ACL data: handle 11 flags 0x02 dlen 16
    A2MP: Discover req: mtu/mps 670 mask: 0x0000
< ACL data: handle 11 flags 0x00 dlen 22
    A2MP: Discover rsp: mtu/mps 670 mask: 0x0000
      Controller list:
        id 0 type 0 (BR-EDR) status 0x01 (Bluetooth only)
        id 1 type 1 (802.11 AMP) status 0x01 (Bluetooth only)
...

Signed-off-by: Andrei Emeltchenko <andrei.emeltchenko@intel.com>
---
 include/net/bluetooth/a2mp.h     |    2 +
 include/net/bluetooth/hci_core.h |   13 ++++++
 net/bluetooth/a2mp.c             |   85 ++++++++++++++++++++++++++++++++++++++
 3 files changed, 100 insertions(+)

diff --git a/include/net/bluetooth/a2mp.h b/include/net/bluetooth/a2mp.h
index 2eb46ee..c9aa9c5 100644
--- a/include/net/bluetooth/a2mp.h
+++ b/include/net/bluetooth/a2mp.h
@@ -15,6 +15,8 @@
 #ifndef __A2MP_H
 #define __A2MP_H
 
+#define A2MP_FEAT_EXT	0x8000
+
 struct amp_mgr {
 	struct list_head	list;
 	struct l2cap_conn	*l2cap_conn;
diff --git a/include/net/bluetooth/hci_core.h b/include/net/bluetooth/hci_core.h
index 16ab35d..67e8eaa 100644
--- a/include/net/bluetooth/hci_core.h
+++ b/include/net/bluetooth/hci_core.h
@@ -644,6 +644,19 @@ static inline void hci_set_drvdata(struct hci_dev *hdev, void *data)
 	dev_set_drvdata(&hdev->dev, data);
 }
 
+/* hci_dev_list shall be locked */
+static inline uint8_t __hci_num_ctrl(void)
+{
+	uint8_t count = 0;
+	struct list_head *p;
+
+	list_for_each(p, &hci_dev_list) {
+		count++;
+	}
+
+	return count;
+}
+
 struct hci_dev *hci_dev_get(int index);
 struct hci_dev *hci_get_route(bdaddr_t *src, bdaddr_t *dst);
 
diff --git a/net/bluetooth/a2mp.c b/net/bluetooth/a2mp.c
index 4f3e6f9..b4eb294 100644
--- a/net/bluetooth/a2mp.c
+++ b/net/bluetooth/a2mp.c
@@ -63,6 +63,36 @@ static void a2mp_send(struct amp_mgr *mgr, u8 code, u8 ident, u16 len,
 	kfree(cmd);
 }
 
+static inline void __a2mp_cl_bredr(struct a2mp_cl *cl)
+{
+	cl->id = 0;
+	cl->type = 0;
+	cl->status = 1;
+}
+
+/* hci_dev_list shall be locked */
+static void __a2mp_add_cl(struct amp_mgr *mgr, struct a2mp_cl *cl, u8 num_ctrl)
+{
+	int i = 0;
+	struct hci_dev *hdev;
+
+	__a2mp_cl_bredr(cl);
+
+	list_for_each_entry(hdev, &hci_dev_list, list) {
+		/* Iterate through AMP controllers */
+		if (hdev->id == HCI_BREDR_ID)
+			continue;
+
+		/* Starting from second entry */
+		if (++i >= num_ctrl)
+			return;
+
+		cl[i].id = hdev->id;
+		cl[i].type = hdev->amp_type;
+		cl[i].status = hdev->amp_status;
+	}
+}
+
 /* Processing A2MP messages */
 static int a2mp_command_rej(struct amp_mgr *mgr, struct sk_buff *skb,
 			    struct a2mp_cmd *hdr)
@@ -79,6 +109,58 @@ static int a2mp_command_rej(struct amp_mgr *mgr, struct sk_buff *skb,
 	return 0;
 }
 
+static inline int a2mp_discover_req(struct amp_mgr *mgr, struct sk_buff *skb,
+				    struct a2mp_cmd *hdr)
+{
+	struct a2mp_discov_req *req = (struct a2mp_discov_req *) skb->data;
+	u16 len = le16_to_cpu(hdr->len);
+	struct a2mp_discov_rsp *rsp;
+	u16 ext_feat;
+	u8 num_ctrl;
+
+	if (len < sizeof(*req))
+		return -EINVAL;
+
+	skb_pull(skb, sizeof(*req));
+
+	ext_feat = le16_to_cpu(req->ext_feat);
+
+	BT_DBG("mtu %d efm 0x%4.4x", le16_to_cpu(req->mtu), ext_feat);
+
+	/* check that packet is not broken for now */
+	while (ext_feat & A2MP_FEAT_EXT) {
+		if (len < sizeof(ext_feat))
+			return -EINVAL;
+
+		ext_feat = get_unaligned_le16(skb->data);
+		BT_DBG("efm 0x%4.4x", ext_feat);
+		len -= sizeof(ext_feat);
+		skb_pull(skb, sizeof(ext_feat));
+	}
+
+	read_lock(&hci_dev_list_lock);
+
+	num_ctrl = __hci_num_ctrl();
+	len = num_ctrl * sizeof(struct a2mp_cl) + sizeof(*rsp);
+	rsp = kmalloc(len, GFP_ATOMIC);
+	if (!rsp) {
+		read_unlock(&hci_dev_list_lock);
+		return -ENOMEM;
+	}
+
+	rsp->mtu = cpu_to_le16(L2CAP_A2MP_DEFAULT_MTU);
+	rsp->ext_feat = 0;
+
+	__a2mp_add_cl(mgr, rsp->cl, num_ctrl);
+
+	read_unlock(&hci_dev_list_lock);
+
+	a2mp_send(mgr, A2MP_DISCOVER_RSP, hdr->ident, len, rsp);
+
+	kfree(rsp);
+	return 0;
+}
+
 /* Handle A2MP signalling */
 static int a2mp_chan_recv_cb(void *data, struct sk_buff *skb)
 {
@@ -109,6 +191,9 @@ static int a2mp_chan_recv_cb(void *data, struct sk_buff *skb)
 			break;
 
 		case A2MP_DISCOVER_REQ:
+			err = a2mp_discover_req(mgr, skb, hdr);
+			break;
+
 		case A2MP_CHANGE_NOTIFY:
 		case A2MP_GETINFO_REQ:
 		case A2MP_GETAMPASSOC_REQ:
-- 
1.7.9.5