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authorOliver Hartkopp <socketcan@hartkopp.net>2010-10-19 09:32:04 +0000
committerDavid S. Miller <davem@davemloft.net>2010-10-21 04:27:03 -0700
commit1e55659ce6ddb5247cee0b1f720d77a799902b85 (patch)
tree335e43324d5ad5e0979fb30e333cb1a4e1a47085 /net/can
parent32a875adcdcf5f470bf967250cfd01722e23844f (diff)
downloadlinux-2.6.38-lt-ux500-1e55659ce6ddb5247cee0b1f720d77a799902b85.tar.gz
can-raw: add msg_flags to distinguish local traffic
CAN has no addressing scheme. It is currently impossible for userspace to tell is a received CAN frame comes from another process on the local host, or from a remote CAN device. This patch add support for userspace applications to distinguish between 'own', 'local' and 'remote' CAN traffic. The distinction is made by returning flags in msg->msg_flags in the call to recvmsg(). The added documentation explains the introduced flags. Signed-off-by: Kurt Van Dijck <kurt.van.dijck@eia.be> Signed-off-by: Oliver Hartkopp <socketcan@hartkopp.net> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/can')
-rw-r--r--net/can/raw.c33
1 files changed, 30 insertions, 3 deletions
diff --git a/net/can/raw.c b/net/can/raw.c
index 7d77e67e57a..e88f610fdb7 100644
--- a/net/can/raw.c
+++ b/net/can/raw.c
@@ -90,23 +90,39 @@ struct raw_sock {
can_err_mask_t err_mask;
};
+/*
+ * Return pointer to store the extra msg flags for raw_recvmsg().
+ * We use the space of one unsigned int beyond the 'struct sockaddr_can'
+ * in skb->cb.
+ */
+static inline unsigned int *raw_flags(struct sk_buff *skb)
+{
+ BUILD_BUG_ON(sizeof(skb->cb) <= (sizeof(struct sockaddr_can) +
+ sizeof(unsigned int)));
+
+ /* return pointer after struct sockaddr_can */
+ return (unsigned int *)(&((struct sockaddr_can *)skb->cb)[1]);
+}
+
static inline struct raw_sock *raw_sk(const struct sock *sk)
{
return (struct raw_sock *)sk;
}
-static void raw_rcv(struct sk_buff *skb, void *data)
+static void raw_rcv(struct sk_buff *oskb, void *data)
{
struct sock *sk = (struct sock *)data;
struct raw_sock *ro = raw_sk(sk);
struct sockaddr_can *addr;
+ struct sk_buff *skb;
+ unsigned int *pflags;
/* check the received tx sock reference */
- if (!ro->recv_own_msgs && skb->sk == sk)
+ if (!ro->recv_own_msgs && oskb->sk == sk)
return;
/* clone the given skb to be able to enqueue it into the rcv queue */
- skb = skb_clone(skb, GFP_ATOMIC);
+ skb = skb_clone(oskb, GFP_ATOMIC);
if (!skb)
return;
@@ -123,6 +139,14 @@ static void raw_rcv(struct sk_buff *skb, void *data)
addr->can_family = AF_CAN;
addr->can_ifindex = skb->dev->ifindex;
+ /* add CAN specific message flags for raw_recvmsg() */
+ pflags = raw_flags(skb);
+ *pflags = 0;
+ if (oskb->sk)
+ *pflags |= MSG_DONTROUTE;
+ if (oskb->sk == sk)
+ *pflags |= MSG_CONFIRM;
+
if (sock_queue_rcv_skb(sk, skb) < 0)
kfree_skb(skb);
}
@@ -707,6 +731,9 @@ static int raw_recvmsg(struct kiocb *iocb, struct socket *sock,
memcpy(msg->msg_name, skb->cb, msg->msg_namelen);
}
+ /* assign the flags that have been recorded in raw_rcv() */
+ msg->msg_flags |= *(raw_flags(skb));
+
skb_free_datagram(sk, skb);
return size;