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| author | Oliver Hartkopp <socketcan@hartkopp.net> | 2010-10-19 09:32:04 +0000 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2010-10-21 04:27:03 -0700 |
| commit | 1e55659ce6ddb5247cee0b1f720d77a799902b85 (patch) | |
| tree | 335e43324d5ad5e0979fb30e333cb1a4e1a47085 /net/can/raw.c | |
| parent | 32a875adcdcf5f470bf967250cfd01722e23844f (diff) | |
| download | linux-riscv-1e55659ce6ddb5247cee0b1f720d77a799902b85.tar.gz linux-riscv-1e55659ce6ddb5247cee0b1f720d77a799902b85.tar.bz2 linux-riscv-1e55659ce6ddb5247cee0b1f720d77a799902b85.zip | |
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/raw.c')
| -rw-r--r-- | net/can/raw.c | 33 |
1 files changed, 30 insertions, 3 deletions
diff --git a/net/can/raw.c b/net/can/raw.c index 7d77e67e57af..e88f610fdb7b 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; |