ieee802154: introduce wpan_dev_header_ops

The current header_ops callback structure of net device are used mostly
from 802.15.4 upper-layers. Because this callback structure is a very
generic one, which is also used by e.g. DGRAM AF_PACKET sockets, we
can't make this callback structure 802.15.4 specific which is currently
is.

I saw the smallest "constraint" for calling this callback with
dev_hard_header/dev_parse_header by AF_PACKET which assign a 8 byte
array for address void pointers. Currently 802.15.4 specific protocols
like af802154 and 6LoWPAN will assign the "struct ieee802154_addr" as
these parameters which is greater than 8 bytes. The current callback
implementation for header_ops.create assumes always a complete
"struct ieee802154_addr" which AF_PACKET can't never handled and is
greater than 8 bytes.

For that reason we introduce now a "generic" create/parse header_ops
callback which allows handling with intra-pan extended addresses only.
This allows a small use-case with AF_PACKET to send "somehow" a valid
dataframe over DGRAM.

To keeping the current dev_hard_header behaviour we introduce a similar
callback structure "wpan_dev_header_ops" which contains 802.15.4 specific
upper-layer header creation functionality, which can be called by
wpan_dev_hard_header.

Signed-off-by: Alexander Aring <alex.aring@gmail.com>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>

2 files changed, 33 insertions, 9 deletions

diff --git a/include/net/cfg802154.h b/include/net/cfg802154.h
index 76b1ffaea863..242273ccf34b 100644
--- a/include/net/cfg802154.h
+++ b/include/net/cfg802154.h
@@ -167,6 +167,26 @@ struct wpan_phy {
 	char priv[0] __aligned(NETDEV_ALIGN);
 };
 
+struct ieee802154_addr {
+	u8 mode;
+	__le16 pan_id;
+	union {
+		__le16 short_addr;
+		__le64 extended_addr;
+	};
+};
+
+struct wpan_dev_header_ops {
+	/* TODO create callback currently assumes ieee802154_mac_cb inside
+	 * skb->cb. This should be changed to give these information as
+	 * parameter.
+	 */
+	int	(*create)(struct sk_buff *skb, struct net_device *dev,
+			  const struct ieee802154_addr *daddr,
+			  const struct ieee802154_addr *saddr,
+			  unsigned int len);
+};
+
 struct wpan_dev {
 	struct wpan_phy *wpan_phy;
 	int iftype;
@@ -175,6 +195,8 @@ struct wpan_dev {
 	struct list_head list;
 	struct net_device *netdev;
 
+	const struct wpan_dev_header_ops *header_ops;
+
 	/* lowpan interface, set when the wpan_dev belongs to one lowpan_dev */
 	struct net_device *lowpan_dev;
 
@@ -205,6 +227,17 @@ struct wpan_dev {
 
 #define to_phy(_dev)	container_of(_dev, struct wpan_phy, dev)
 
+static inline int
+wpan_dev_hard_header(struct sk_buff *skb, struct net_device *dev,
+		     const struct ieee802154_addr *daddr,
+		     const struct ieee802154_addr *saddr,
+		     unsigned int len)
+{
+	struct wpan_dev *wpan_dev = dev->ieee802154_ptr;
+
+	return wpan_dev->header_ops->create(skb, dev, daddr, saddr, len);
+}
+
 struct wpan_phy *
 wpan_phy_new(const struct cfg802154_ops *ops, size_t priv_size);
 static inline void wpan_phy_set_dev(struct wpan_phy *phy, struct device *dev)
diff --git a/include/net/ieee802154_netdev.h b/include/net/ieee802154_netdev.h
index 95a71bc113b3..aebb9d8d7a11 100644
--- a/include/net/ieee802154_netdev.h
+++ b/include/net/ieee802154_netdev.h
@@ -50,15 +50,6 @@ struct ieee802154_sechdr {
 	};
 };
 
-struct ieee802154_addr {
-	u8 mode;
-	__le16 pan_id;
-	union {
-		__le16 short_addr;
-		__le64 extended_addr;
-	};
-};
-
 struct ieee802154_hdr_fc {
 #if defined(__LITTLE_ENDIAN_BITFIELD)
 	u16 type:3,