loopback problem with BCM, RAW using, Daniele Venzano

loopback problem with BCM, RAW using, Daniele Venzano

[Mahesh.Maharjan-EXT]

hello to all,
 
Thanks to Oliver.  Suggesting for using both RAW n' BCM together .

But As Already discussed by Daniele Venzano : The loopback problems  are 
occurring , When Sending can_message from BCM , RAW also  trying to read 
all message  dynamically. ( Suppose we don't need filter in system).And  I 
want to ignore all message  coming to same my node Again.  Even I used 
same  option  for setting "loopback mode"in raw socket.  But suggestion 
mention by Daniele. : can_send(skb, 1)  from bcm.c. Sound pretty simple. 
But doesn't look better to change directly from source code. Yeah , Even I 
changed for testing .. "no work done "....

Help  !!!


With Regards,

Mahesh Maharjan

Re: loopback problem with BCM, RAW using, Daniele Venzano

[Oliver Hartkopp]

[-- Attachment #1: Type: text/plain, Size: 5637 bytes --]

Hello Mahesh,

i tried to generate a patch that allows you to disable the reception of local
generated CAN messages.

The patch is based on Kernel 3.6-rc2 - but it should be easy to backport by
hand.

Can you try it, if it solves your problem?

Maybe this extension to the CAN_RAW socket is useful for other people also ...

Regards,
Oliver

diff --git a/Documentation/networking/can.txt b/Documentation/networking/can.txt
index 820f553..b6d28bd 100644
--- a/Documentation/networking/can.txt
+++ b/Documentation/networking/can.txt
@@ -23,7 +23,8 @@ This file contains
       4.1.3 RAW socket option CAN_RAW_LOOPBACK
       4.1.4 RAW socket option CAN_RAW_RECV_OWN_MSGS
       4.1.5 RAW socket option CAN_RAW_FD_FRAMES
-      4.1.6 RAW socket returned message flags
+      4.1.6 RAW socket option CAN_RAW_RECV_HOST_MSGS
+      4.1.7 RAW socket returned message flags
     4.2 Broadcast Manager protocol sockets (SOCK_DGRAM)
     4.3 connected transport protocols (SOCK_SEQPACKET)
     4.4 unconnected transport protocols (SOCK_DGRAM)
@@ -581,7 +582,23 @@ solution for a couple of reasons:
   CAN FD frames by checking if the device maximum transfer unit is CANFD_MTU.
   The CAN device MTU can be retrieved e.g. with a SIOCGIFMTU ioctl() syscall.

-  4.1.6 RAW socket returned message flags
+  4.1.6 RAW socket option CAN_RAW_RECV_HOST_MSGS
+
+  When the local loopback is enabled, all the sent CAN frames are
+  looped back to the open CAN sockets that registered for the CAN
+  frames' CAN-ID on this given interface to meet the multi user
+  needs. The reception of the CAN frames originated from the local host
+  is therefore a wanted behaviour and enabled by default.
+
+  When the reception of locally generated CAN frames is not wanted, this
+  default behaviour may be changed on demand:
+
+    int recv_host_msgs = 0; /* 0 = disabled, 1 = enabled (default) */
+
+    setsockopt(s, SOL_CAN_RAW, CAN_RAW_RECV_HOST_MSGS,
+               &recv_host_msgs, sizeof(recv_host_msgs));
+
+  4.1.7 RAW socket returned message flags

   When using recvmsg() call, the msg->msg_flags may contain following flags:

diff --git a/include/linux/can/raw.h b/include/linux/can/raw.h
index a814062..0d53fb6 100644
--- a/include/linux/can/raw.h
+++ b/include/linux/can/raw.h
@@ -25,6 +25,7 @@ enum {
        CAN_RAW_LOOPBACK,       /* local loopback (default:on)       */
        CAN_RAW_RECV_OWN_MSGS,  /* receive my own msgs (default:off) */
        CAN_RAW_FD_FRAMES,      /* allow CAN FD frames (default:off) */
+       CAN_RAW_RECV_HOST_MSGS, /* recv local host msgs (default:on) */
 };

 #endif
diff --git a/net/can/raw.c b/net/can/raw.c
index 3e9c893..0cfbc16 100644
--- a/net/can/raw.c
+++ b/net/can/raw.c
@@ -83,6 +83,7 @@ struct raw_sock {
        int loopback;
        int recv_own_msgs;
        int fd_frames;
+       int recv_host_msgs;
        int count;                 /* number of active filters */
        struct can_filter dfilter; /* default/single filter */
        struct can_filter *filter; /* pointer to filter(s) */
@@ -120,6 +121,10 @@ static void raw_rcv(struct sk_buff *oskb, void *data)
        if (!ro->recv_own_msgs && oskb->sk == sk)
                return;

+       /* check if we need to skip locally generated messages */
+       if (!ro->recv_host_msgs && oskb->sk)
+               return;
+
        /* do not pass frames with DLC > 8 to a legacy socket */
        if (!ro->fd_frames) {
                struct canfd_frame *cfd = (struct canfd_frame *)oskb->data;
@@ -301,6 +306,7 @@ static int raw_init(struct sock *sk)
        ro->loopback         = 1;
        ro->recv_own_msgs    = 0;
        ro->fd_frames        = 0;
+       ro->recv_host_msgs   = 1;

        /* set notifier */
        ro->notifier.notifier_call = raw_notifier;
@@ -588,6 +594,15 @@ static int raw_setsockopt(struct socket *sock, int level,
int optname,

                break;

+       case CAN_RAW_RECV_HOST_MSGS:
+               if (optlen != sizeof(ro->recv_host_msgs))
+                       return -EINVAL;
+
+               if (copy_from_user(&ro->recv_host_msgs, optval, optlen))
+                       return -EFAULT;
+
+               break;
+
        default:
                return -ENOPROTOOPT;
        }
@@ -652,6 +667,12 @@ static int raw_getsockopt(struct socket *sock, int level,
int optname,
                val = &ro->fd_frames;
                break;

+       case CAN_RAW_RECV_HOST_MSGS:
+               if (len > sizeof(int))
+                       len = sizeof(int);
+               val = &ro->recv_host_msgs;
+               break;
+
        default:
                return -ENOPROTOOPT;
        }




Mahesh.Maharjan-EXT@continental-corporation.com hat am 17. August 2012 um 12:58
geschrieben:> hello to all,
> 
> Thanks to Oliver.  Suggesting for using both RAW n' BCM together .
>
> But As Already discussed by Daniele Venzano : The loopback problems  are
> occurring , When Sending can_message from BCM , RAW also  trying to read
> all message  dynamically. ( Suppose we don't need filter in system).And  I
> want to ignore all message  coming to same my node Again.  Even I used
> same  option  for setting "loopback mode"in raw socket.  But suggestion
> mention by Daniele. : can_send(skb, 1)  from bcm.c. Sound pretty simple.
> But doesn't look better to change directly from source code. Yeah , Even I
> changed for testing .. "no work done "....
>
> Help  !!!
>
>
> With Regards,
>
> Mahesh Maharjan
>
>
> --
> To unsubscribe from this list: send the line "unsubscribe linux-can" in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at  http://vger.kernel.org/majordomo-info.html

[-- Attachment #2: recv_hosts_msgs.patch --]
[-- Type: text/x-patch, Size: 3867 bytes --]

diff --git a/Documentation/networking/can.txt b/Documentation/networking/can.txt
index 820f553..b6d28bd 100644
--- a/Documentation/networking/can.txt
+++ b/Documentation/networking/can.txt
@@ -23,7 +23,8 @@ This file contains
       4.1.3 RAW socket option CAN_RAW_LOOPBACK
       4.1.4 RAW socket option CAN_RAW_RECV_OWN_MSGS
       4.1.5 RAW socket option CAN_RAW_FD_FRAMES
-      4.1.6 RAW socket returned message flags
+      4.1.6 RAW socket option CAN_RAW_RECV_HOST_MSGS
+      4.1.7 RAW socket returned message flags
     4.2 Broadcast Manager protocol sockets (SOCK_DGRAM)
     4.3 connected transport protocols (SOCK_SEQPACKET)
     4.4 unconnected transport protocols (SOCK_DGRAM)
@@ -581,7 +582,23 @@ solution for a couple of reasons:
   CAN FD frames by checking if the device maximum transfer unit is CANFD_MTU.
   The CAN device MTU can be retrieved e.g. with a SIOCGIFMTU ioctl() syscall.
 
-  4.1.6 RAW socket returned message flags
+  4.1.6 RAW socket option CAN_RAW_RECV_HOST_MSGS
+
+  When the local loopback is enabled, all the sent CAN frames are
+  looped back to the open CAN sockets that registered for the CAN
+  frames' CAN-ID on this given interface to meet the multi user
+  needs. The reception of the CAN frames originated from the local host
+  is therefore a wanted behaviour and enabled by default.
+
+  When the reception of locally generated CAN frames is not wanted, this
+  default behaviour may be changed on demand:
+
+    int recv_host_msgs = 0; /* 0 = disabled, 1 = enabled (default) */
+
+    setsockopt(s, SOL_CAN_RAW, CAN_RAW_RECV_HOST_MSGS,
+               &recv_host_msgs, sizeof(recv_host_msgs));
+
+  4.1.7 RAW socket returned message flags
 
   When using recvmsg() call, the msg->msg_flags may contain following flags:
 
diff --git a/include/linux/can/raw.h b/include/linux/can/raw.h
index a814062..0d53fb6 100644
--- a/include/linux/can/raw.h
+++ b/include/linux/can/raw.h
@@ -25,6 +25,7 @@ enum {
 	CAN_RAW_LOOPBACK,	/* local loopback (default:on)       */
 	CAN_RAW_RECV_OWN_MSGS,	/* receive my own msgs (default:off) */
 	CAN_RAW_FD_FRAMES,	/* allow CAN FD frames (default:off) */
+	CAN_RAW_RECV_HOST_MSGS,	/* recv local host msgs (default:on) */
 };
 
 #endif
diff --git a/net/can/raw.c b/net/can/raw.c
index 3e9c893..0cfbc16 100644
--- a/net/can/raw.c
+++ b/net/can/raw.c
@@ -83,6 +83,7 @@ struct raw_sock {
 	int loopback;
 	int recv_own_msgs;
 	int fd_frames;
+	int recv_host_msgs;
 	int count;                 /* number of active filters */
 	struct can_filter dfilter; /* default/single filter */
 	struct can_filter *filter; /* pointer to filter(s) */
@@ -120,6 +121,10 @@ static void raw_rcv(struct sk_buff *oskb, void *data)
 	if (!ro->recv_own_msgs && oskb->sk == sk)
 		return;
 
+	/* check if we need to skip locally generated messages */
+	if (!ro->recv_host_msgs && oskb->sk)
+		return;
+
 	/* do not pass frames with DLC > 8 to a legacy socket */
 	if (!ro->fd_frames) {
 		struct canfd_frame *cfd = (struct canfd_frame *)oskb->data;
@@ -301,6 +306,7 @@ static int raw_init(struct sock *sk)
 	ro->loopback         = 1;
 	ro->recv_own_msgs    = 0;
 	ro->fd_frames        = 0;
+	ro->recv_host_msgs   = 1;
 
 	/* set notifier */
 	ro->notifier.notifier_call = raw_notifier;
@@ -588,6 +594,15 @@ static int raw_setsockopt(struct socket *sock, int level, int optname,
 
 		break;
 
+	case CAN_RAW_RECV_HOST_MSGS:
+		if (optlen != sizeof(ro->recv_host_msgs))
+			return -EINVAL;
+
+		if (copy_from_user(&ro->recv_host_msgs, optval, optlen))
+			return -EFAULT;
+
+		break;
+
 	default:
 		return -ENOPROTOOPT;
 	}
@@ -652,6 +667,12 @@ static int raw_getsockopt(struct socket *sock, int level, int optname,
 		val = &ro->fd_frames;
 		break;
 
+	case CAN_RAW_RECV_HOST_MSGS:
+		if (len > sizeof(int))
+			len = sizeof(int);
+		val = &ro->recv_host_msgs;
+		break;
+
 	default:
 		return -ENOPROTOOPT;
 	}

Re: loopback problem with BCM, RAW using, Daniele Venzano

[Kurt Van Dijck]

Oliver,

I did not follow this thread in depth.

The patch looks minimal, but I doubt its usefullness.
In a proper designed CAN system, each node uses distinct CAN-ids.
Therefore, filtering out local traffic can always be accomplished
with the current filtering (RTR frames are an exception, but are
irrelevant here).

userspace can test flags (MSG_DONTROUTE) to decide if a received
frame is from <localhost> or remote.
So I don't see the problem that you're addressing with this patch.

Kind regards,
Kurt

On Fri, Aug 17, 2012 at 02:13:57PM +0200, Oliver Hartkopp wrote:
> Hello Mahesh,
> 
> i tried to generate a patch that allows you to disable the reception of local
> generated CAN messages.
> 
> The patch is based on Kernel 3.6-rc2 - but it should be easy to backport by
> hand.
> 
> Can you try it, if it solves your problem?
> 
> Maybe this extension to the CAN_RAW socket is useful for other people also ...
> 
> Regards,
> Oliver
> 
> diff --git a/Documentation/networking/can.txt b/Documentation/networking/can.txt
> index 820f553..b6d28bd 100644
> --- a/Documentation/networking/can.txt
> +++ b/Documentation/networking/can.txt
> @@ -23,7 +23,8 @@ This file contains
>        4.1.3 RAW socket option CAN_RAW_LOOPBACK
>        4.1.4 RAW socket option CAN_RAW_RECV_OWN_MSGS
>        4.1.5 RAW socket option CAN_RAW_FD_FRAMES
> -      4.1.6 RAW socket returned message flags
> +      4.1.6 RAW socket option CAN_RAW_RECV_HOST_MSGS
> +      4.1.7 RAW socket returned message flags
>      4.2 Broadcast Manager protocol sockets (SOCK_DGRAM)
>      4.3 connected transport protocols (SOCK_SEQPACKET)
>      4.4 unconnected transport protocols (SOCK_DGRAM)
> @@ -581,7 +582,23 @@ solution for a couple of reasons:
>    CAN FD frames by checking if the device maximum transfer unit is CANFD_MTU.
>    The CAN device MTU can be retrieved e.g. with a SIOCGIFMTU ioctl() syscall.
> 
> -  4.1.6 RAW socket returned message flags
> +  4.1.6 RAW socket option CAN_RAW_RECV_HOST_MSGS
> +
> +  When the local loopback is enabled, all the sent CAN frames are
> +  looped back to the open CAN sockets that registered for the CAN
> +  frames' CAN-ID on this given interface to meet the multi user
> +  needs. The reception of the CAN frames originated from the local host
> +  is therefore a wanted behaviour and enabled by default.
> +
> +  When the reception of locally generated CAN frames is not wanted, this
> +  default behaviour may be changed on demand:
> +
> +    int recv_host_msgs = 0; /* 0 = disabled, 1 = enabled (default) */
> +
> +    setsockopt(s, SOL_CAN_RAW, CAN_RAW_RECV_HOST_MSGS,
> +               &recv_host_msgs, sizeof(recv_host_msgs));
> +
> +  4.1.7 RAW socket returned message flags
> 
>    When using recvmsg() call, the msg->msg_flags may contain following flags:
> 
> diff --git a/include/linux/can/raw.h b/include/linux/can/raw.h
> index a814062..0d53fb6 100644
> --- a/include/linux/can/raw.h
> +++ b/include/linux/can/raw.h
> @@ -25,6 +25,7 @@ enum {
>         CAN_RAW_LOOPBACK,       /* local loopback (default:on)       */
>         CAN_RAW_RECV_OWN_MSGS,  /* receive my own msgs (default:off) */
>         CAN_RAW_FD_FRAMES,      /* allow CAN FD frames (default:off) */
> +       CAN_RAW_RECV_HOST_MSGS, /* recv local host msgs (default:on) */
>  };
> 
>  #endif
> diff --git a/net/can/raw.c b/net/can/raw.c
> index 3e9c893..0cfbc16 100644
> --- a/net/can/raw.c
> +++ b/net/can/raw.c
> @@ -83,6 +83,7 @@ struct raw_sock {
>         int loopback;
>         int recv_own_msgs;
>         int fd_frames;
> +       int recv_host_msgs;
>         int count;                 /* number of active filters */
>         struct can_filter dfilter; /* default/single filter */
>         struct can_filter *filter; /* pointer to filter(s) */
> @@ -120,6 +121,10 @@ static void raw_rcv(struct sk_buff *oskb, void *data)
>         if (!ro->recv_own_msgs && oskb->sk == sk)
>                 return;
> 
> +       /* check if we need to skip locally generated messages */
> +       if (!ro->recv_host_msgs && oskb->sk)
> +               return;
> +
>         /* do not pass frames with DLC > 8 to a legacy socket */
>         if (!ro->fd_frames) {
>                 struct canfd_frame *cfd = (struct canfd_frame *)oskb->data;
> @@ -301,6 +306,7 @@ static int raw_init(struct sock *sk)
>         ro->loopback         = 1;
>         ro->recv_own_msgs    = 0;
>         ro->fd_frames        = 0;
> +       ro->recv_host_msgs   = 1;
> 
>         /* set notifier */
>         ro->notifier.notifier_call = raw_notifier;
> @@ -588,6 +594,15 @@ static int raw_setsockopt(struct socket *sock, int level,
> int optname,
> 
>                 break;
> 
> +       case CAN_RAW_RECV_HOST_MSGS:
> +               if (optlen != sizeof(ro->recv_host_msgs))
> +                       return -EINVAL;
> +
> +               if (copy_from_user(&ro->recv_host_msgs, optval, optlen))
> +                       return -EFAULT;
> +
> +               break;
> +
>         default:
>                 return -ENOPROTOOPT;
>         }
> @@ -652,6 +667,12 @@ static int raw_getsockopt(struct socket *sock, int level,
> int optname,
>                 val = &ro->fd_frames;
>                 break;
> 
> +       case CAN_RAW_RECV_HOST_MSGS:
> +               if (len > sizeof(int))
> +                       len = sizeof(int);
> +               val = &ro->recv_host_msgs;
> +               break;
> +
>         default:
>                 return -ENOPROTOOPT;
>         }
> 
> 
> 
> 
> Mahesh.Maharjan-EXT@continental-corporation.com hat am 17. August 2012 um 12:58
> geschrieben:> hello to all,
> > 
> > Thanks to Oliver.  Suggesting for using both RAW n' BCM together .
> >
> > But As Already discussed by Daniele Venzano : The loopback problems  are
> > occurring , When Sending can_message from BCM , RAW also  trying to read
> > all message  dynamically. ( Suppose we don't need filter in system).And  I
> > want to ignore all message  coming to same my node Again.  Even I used
> > same  option  for setting "loopback mode"in raw socket.  But suggestion
> > mention by Daniele. : can_send(skb, 1)  from bcm.c. Sound pretty simple.
> > But doesn't look better to change directly from source code. Yeah , Even I
> > changed for testing .. "no work done "....
> >
> > Help  !!!
> >
> >
> > With Regards,
> >
> > Mahesh Maharjan
> >
> >
> > --
> > To unsubscribe from this list: send the line "unsubscribe linux-can" in
> > the body of a message to majordomo@vger.kernel.org
> > More majordomo info at  http://vger.kernel.org/majordomo-info.html

> diff --git a/Documentation/networking/can.txt b/Documentation/networking/can.txt
> index 820f553..b6d28bd 100644
> --- a/Documentation/networking/can.txt
> +++ b/Documentation/networking/can.txt
> @@ -23,7 +23,8 @@ This file contains
>        4.1.3 RAW socket option CAN_RAW_LOOPBACK
>        4.1.4 RAW socket option CAN_RAW_RECV_OWN_MSGS
>        4.1.5 RAW socket option CAN_RAW_FD_FRAMES
> -      4.1.6 RAW socket returned message flags
> +      4.1.6 RAW socket option CAN_RAW_RECV_HOST_MSGS
> +      4.1.7 RAW socket returned message flags
>      4.2 Broadcast Manager protocol sockets (SOCK_DGRAM)
>      4.3 connected transport protocols (SOCK_SEQPACKET)
>      4.4 unconnected transport protocols (SOCK_DGRAM)
> @@ -581,7 +582,23 @@ solution for a couple of reasons:
>    CAN FD frames by checking if the device maximum transfer unit is CANFD_MTU.
>    The CAN device MTU can be retrieved e.g. with a SIOCGIFMTU ioctl() syscall.
>  
> -  4.1.6 RAW socket returned message flags
> +  4.1.6 RAW socket option CAN_RAW_RECV_HOST_MSGS
> +
> +  When the local loopback is enabled, all the sent CAN frames are
> +  looped back to the open CAN sockets that registered for the CAN
> +  frames' CAN-ID on this given interface to meet the multi user
> +  needs. The reception of the CAN frames originated from the local host
> +  is therefore a wanted behaviour and enabled by default.
> +
> +  When the reception of locally generated CAN frames is not wanted, this
> +  default behaviour may be changed on demand:
> +
> +    int recv_host_msgs = 0; /* 0 = disabled, 1 = enabled (default) */
> +
> +    setsockopt(s, SOL_CAN_RAW, CAN_RAW_RECV_HOST_MSGS,
> +               &recv_host_msgs, sizeof(recv_host_msgs));
> +
> +  4.1.7 RAW socket returned message flags
>  
>    When using recvmsg() call, the msg->msg_flags may contain following flags:
>  
> diff --git a/include/linux/can/raw.h b/include/linux/can/raw.h
> index a814062..0d53fb6 100644
> --- a/include/linux/can/raw.h
> +++ b/include/linux/can/raw.h
> @@ -25,6 +25,7 @@ enum {
>  	CAN_RAW_LOOPBACK,	/* local loopback (default:on)       */
>  	CAN_RAW_RECV_OWN_MSGS,	/* receive my own msgs (default:off) */
>  	CAN_RAW_FD_FRAMES,	/* allow CAN FD frames (default:off) */
> +	CAN_RAW_RECV_HOST_MSGS,	/* recv local host msgs (default:on) */
>  };
>  
>  #endif
> diff --git a/net/can/raw.c b/net/can/raw.c
> index 3e9c893..0cfbc16 100644
> --- a/net/can/raw.c
> +++ b/net/can/raw.c
> @@ -83,6 +83,7 @@ struct raw_sock {
>  	int loopback;
>  	int recv_own_msgs;
>  	int fd_frames;
> +	int recv_host_msgs;
>  	int count;                 /* number of active filters */
>  	struct can_filter dfilter; /* default/single filter */
>  	struct can_filter *filter; /* pointer to filter(s) */
> @@ -120,6 +121,10 @@ static void raw_rcv(struct sk_buff *oskb, void *data)
>  	if (!ro->recv_own_msgs && oskb->sk == sk)
>  		return;
>  
> +	/* check if we need to skip locally generated messages */
> +	if (!ro->recv_host_msgs && oskb->sk)
> +		return;
> +
>  	/* do not pass frames with DLC > 8 to a legacy socket */
>  	if (!ro->fd_frames) {
>  		struct canfd_frame *cfd = (struct canfd_frame *)oskb->data;
> @@ -301,6 +306,7 @@ static int raw_init(struct sock *sk)
>  	ro->loopback         = 1;
>  	ro->recv_own_msgs    = 0;
>  	ro->fd_frames        = 0;
> +	ro->recv_host_msgs   = 1;
>  
>  	/* set notifier */
>  	ro->notifier.notifier_call = raw_notifier;
> @@ -588,6 +594,15 @@ static int raw_setsockopt(struct socket *sock, int level, int optname,
>  
>  		break;
>  
> +	case CAN_RAW_RECV_HOST_MSGS:
> +		if (optlen != sizeof(ro->recv_host_msgs))
> +			return -EINVAL;
> +
> +		if (copy_from_user(&ro->recv_host_msgs, optval, optlen))
> +			return -EFAULT;
> +
> +		break;
> +
>  	default:
>  		return -ENOPROTOOPT;
>  	}
> @@ -652,6 +667,12 @@ static int raw_getsockopt(struct socket *sock, int level, int optname,
>  		val = &ro->fd_frames;
>  		break;
>  
> +	case CAN_RAW_RECV_HOST_MSGS:
> +		if (len > sizeof(int))
> +			len = sizeof(int);
> +		val = &ro->recv_host_msgs;
> +		break;
> +
>  	default:
>  		return -ENOPROTOOPT;
>  	}


-- 
Kurt Van Dijck
GRAMMER EiA ELECTRONICS
http://www.eia.be
kurt.van.dijck@eia.be
+32-38708534

receiving CAN from remote hosts only

[Kurt Van Dijck]

Mahesh,

I realize that I only mentioned the MSG_DONTROUTE flags, but did not
provide any clue how to get started.

If I understand your problem well, your transmitting part is working
well using CAN_BCM, and you want to receive all traffic from remote hosts
only, using CAN_RAW as Oliver suggested.

I you read this,

http://git.kernel.org/?p=linux/kernel/git/torvalds/linux.git;a=commit;h=1e55659ce6ddb5247cee0b1f720d77a799902b85

you will notice the use of MSG_DONTROUTE.
You need to use recvmsg() instead of recv(). You can see an example use
of recvmsg() in candump.c.

Your receive loop could then look as follows:

	struct msghdr msg;

	while (1) {
		...
		msg.msg_flags = 0;
		....

		ret = recvfrom(cansock, &msg, 0);

		if (msg.msg_flags & MSG_DONTROUTE)
			/* frame from localhost */
			continue;

		/* do some stuff with frame from remote host */
	}

I hope you will find a solution ...

Kind regards,
Kurt

On Wed, Aug 22, 2012 at 10:57:08AM +0200, Kurt Van Dijck wrote:
> Oliver,
> 
> I did not follow this thread in depth.
> 
> The patch looks minimal, but I doubt its usefullness.
> In a proper designed CAN system, each node uses distinct CAN-ids.
> Therefore, filtering out local traffic can always be accomplished
> with the current filtering (RTR frames are an exception, but are
> irrelevant here).
> 
> userspace can test flags (MSG_DONTROUTE) to decide if a received
> frame is from <localhost> or remote.
> So I don't see the problem that you're addressing with this patch.
> 
> Kind regards,
> Kurt
> 
> On Fri, Aug 17, 2012 at 02:13:57PM +0200, Oliver Hartkopp wrote:
> > Hello Mahesh,
> > 
> > i tried to generate a patch that allows you to disable the reception of local
> > generated CAN messages.
> > 
> > The patch is based on Kernel 3.6-rc2 - but it should be easy to backport by
> > hand.
> > 
> > Can you try it, if it solves your problem?
> > 
> > Maybe this extension to the CAN_RAW socket is useful for other people also ...
> > 
> > Regards,
> > Oliver
> > 
> > diff --git a/Documentation/networking/can.txt b/Documentation/networking/can.txt
> > index 820f553..b6d28bd 100644
> > --- a/Documentation/networking/can.txt
> > +++ b/Documentation/networking/can.txt
> > @@ -23,7 +23,8 @@ This file contains
> >        4.1.3 RAW socket option CAN_RAW_LOOPBACK
> >        4.1.4 RAW socket option CAN_RAW_RECV_OWN_MSGS
> >        4.1.5 RAW socket option CAN_RAW_FD_FRAMES
> > -      4.1.6 RAW socket returned message flags
> > +      4.1.6 RAW socket option CAN_RAW_RECV_HOST_MSGS
> > +      4.1.7 RAW socket returned message flags
> >      4.2 Broadcast Manager protocol sockets (SOCK_DGRAM)
> >      4.3 connected transport protocols (SOCK_SEQPACKET)
> >      4.4 unconnected transport protocols (SOCK_DGRAM)
> > @@ -581,7 +582,23 @@ solution for a couple of reasons:
> >    CAN FD frames by checking if the device maximum transfer unit is CANFD_MTU.
> >    The CAN device MTU can be retrieved e.g. with a SIOCGIFMTU ioctl() syscall.
> > 
> > -  4.1.6 RAW socket returned message flags
> > +  4.1.6 RAW socket option CAN_RAW_RECV_HOST_MSGS
> > +
> > +  When the local loopback is enabled, all the sent CAN frames are
> > +  looped back to the open CAN sockets that registered for the CAN
> > +  frames' CAN-ID on this given interface to meet the multi user
> > +  needs. The reception of the CAN frames originated from the local host
> > +  is therefore a wanted behaviour and enabled by default.
> > +
> > +  When the reception of locally generated CAN frames is not wanted, this
> > +  default behaviour may be changed on demand:
> > +
> > +    int recv_host_msgs = 0; /* 0 = disabled, 1 = enabled (default) */
> > +
> > +    setsockopt(s, SOL_CAN_RAW, CAN_RAW_RECV_HOST_MSGS,
> > +               &recv_host_msgs, sizeof(recv_host_msgs));
> > +
> > +  4.1.7 RAW socket returned message flags
> > 
> >    When using recvmsg() call, the msg->msg_flags may contain following flags:
> > 
> > diff --git a/include/linux/can/raw.h b/include/linux/can/raw.h
> > index a814062..0d53fb6 100644
> > --- a/include/linux/can/raw.h
> > +++ b/include/linux/can/raw.h
> > @@ -25,6 +25,7 @@ enum {
> >         CAN_RAW_LOOPBACK,       /* local loopback (default:on)       */
> >         CAN_RAW_RECV_OWN_MSGS,  /* receive my own msgs (default:off) */
> >         CAN_RAW_FD_FRAMES,      /* allow CAN FD frames (default:off) */
> > +       CAN_RAW_RECV_HOST_MSGS, /* recv local host msgs (default:on) */
> >  };
> > 
> >  #endif
> > diff --git a/net/can/raw.c b/net/can/raw.c
> > index 3e9c893..0cfbc16 100644
> > --- a/net/can/raw.c
> > +++ b/net/can/raw.c
> > @@ -83,6 +83,7 @@ struct raw_sock {
> >         int loopback;
> >         int recv_own_msgs;
> >         int fd_frames;
> > +       int recv_host_msgs;
> >         int count;                 /* number of active filters */
> >         struct can_filter dfilter; /* default/single filter */
> >         struct can_filter *filter; /* pointer to filter(s) */
> > @@ -120,6 +121,10 @@ static void raw_rcv(struct sk_buff *oskb, void *data)
> >         if (!ro->recv_own_msgs && oskb->sk == sk)
> >                 return;
> > 
> > +       /* check if we need to skip locally generated messages */
> > +       if (!ro->recv_host_msgs && oskb->sk)
> > +               return;
> > +
> >         /* do not pass frames with DLC > 8 to a legacy socket */
> >         if (!ro->fd_frames) {
> >                 struct canfd_frame *cfd = (struct canfd_frame *)oskb->data;
> > @@ -301,6 +306,7 @@ static int raw_init(struct sock *sk)
> >         ro->loopback         = 1;
> >         ro->recv_own_msgs    = 0;
> >         ro->fd_frames        = 0;
> > +       ro->recv_host_msgs   = 1;
> > 
> >         /* set notifier */
> >         ro->notifier.notifier_call = raw_notifier;
> > @@ -588,6 +594,15 @@ static int raw_setsockopt(struct socket *sock, int level,
> > int optname,
> > 
> >                 break;
> > 
> > +       case CAN_RAW_RECV_HOST_MSGS:
> > +               if (optlen != sizeof(ro->recv_host_msgs))
> > +                       return -EINVAL;
> > +
> > +               if (copy_from_user(&ro->recv_host_msgs, optval, optlen))
> > +                       return -EFAULT;
> > +
> > +               break;
> > +
> >         default:
> >                 return -ENOPROTOOPT;
> >         }
> > @@ -652,6 +667,12 @@ static int raw_getsockopt(struct socket *sock, int level,
> > int optname,
> >                 val = &ro->fd_frames;
> >                 break;
> > 
> > +       case CAN_RAW_RECV_HOST_MSGS:
> > +               if (len > sizeof(int))
> > +                       len = sizeof(int);
> > +               val = &ro->recv_host_msgs;
> > +               break;
> > +
> >         default:
> >                 return -ENOPROTOOPT;
> >         }
> > 
> > 
> > 
> > 
> > Mahesh.Maharjan-EXT@continental-corporation.com hat am 17. August 2012 um 12:58
> > geschrieben:> hello to all,
> > > 
> > > Thanks to Oliver.  Suggesting for using both RAW n' BCM together .
> > >
> > > But As Already discussed by Daniele Venzano : The loopback problems  are
> > > occurring , When Sending can_message from BCM , RAW also  trying to read
> > > all message  dynamically. ( Suppose we don't need filter in system).And  I
> > > want to ignore all message  coming to same my node Again.  Even I used
> > > same  option  for setting "loopback mode"in raw socket.  But suggestion
> > > mention by Daniele. : can_send(skb, 1)  from bcm.c. Sound pretty simple.
> > > But doesn't look better to change directly from source code. Yeah , Even I
> > > changed for testing .. "no work done "....
> > >
> > > Help  !!!
> > >
> > >
> > > With Regards,
> > >
> > > Mahesh Maharjan
> > >
> > >
> > > --
> > > To unsubscribe from this list: send the line "unsubscribe linux-can" in
> > > the body of a message to majordomo@vger.kernel.org
> > > More majordomo info at  http://vger.kernel.org/majordomo-info.html
> 
> > diff --git a/Documentation/networking/can.txt b/Documentation/networking/can.txt
> > index 820f553..b6d28bd 100644
> > --- a/Documentation/networking/can.txt
> > +++ b/Documentation/networking/can.txt
> > @@ -23,7 +23,8 @@ This file contains
> >        4.1.3 RAW socket option CAN_RAW_LOOPBACK
> >        4.1.4 RAW socket option CAN_RAW_RECV_OWN_MSGS
> >        4.1.5 RAW socket option CAN_RAW_FD_FRAMES
> > -      4.1.6 RAW socket returned message flags
> > +      4.1.6 RAW socket option CAN_RAW_RECV_HOST_MSGS
> > +      4.1.7 RAW socket returned message flags
> >      4.2 Broadcast Manager protocol sockets (SOCK_DGRAM)
> >      4.3 connected transport protocols (SOCK_SEQPACKET)
> >      4.4 unconnected transport protocols (SOCK_DGRAM)
> > @@ -581,7 +582,23 @@ solution for a couple of reasons:
> >    CAN FD frames by checking if the device maximum transfer unit is CANFD_MTU.
> >    The CAN device MTU can be retrieved e.g. with a SIOCGIFMTU ioctl() syscall.
> >  
> > -  4.1.6 RAW socket returned message flags
> > +  4.1.6 RAW socket option CAN_RAW_RECV_HOST_MSGS
> > +
> > +  When the local loopback is enabled, all the sent CAN frames are
> > +  looped back to the open CAN sockets that registered for the CAN
> > +  frames' CAN-ID on this given interface to meet the multi user
> > +  needs. The reception of the CAN frames originated from the local host
> > +  is therefore a wanted behaviour and enabled by default.
> > +
> > +  When the reception of locally generated CAN frames is not wanted, this
> > +  default behaviour may be changed on demand:
> > +
> > +    int recv_host_msgs = 0; /* 0 = disabled, 1 = enabled (default) */
> > +
> > +    setsockopt(s, SOL_CAN_RAW, CAN_RAW_RECV_HOST_MSGS,
> > +               &recv_host_msgs, sizeof(recv_host_msgs));
> > +
> > +  4.1.7 RAW socket returned message flags
> >  
> >    When using recvmsg() call, the msg->msg_flags may contain following flags:
> >  
> > diff --git a/include/linux/can/raw.h b/include/linux/can/raw.h
> > index a814062..0d53fb6 100644
> > --- a/include/linux/can/raw.h
> > +++ b/include/linux/can/raw.h
> > @@ -25,6 +25,7 @@ enum {
> >  	CAN_RAW_LOOPBACK,	/* local loopback (default:on)       */
> >  	CAN_RAW_RECV_OWN_MSGS,	/* receive my own msgs (default:off) */
> >  	CAN_RAW_FD_FRAMES,	/* allow CAN FD frames (default:off) */
> > +	CAN_RAW_RECV_HOST_MSGS,	/* recv local host msgs (default:on) */
> >  };
> >  
> >  #endif
> > diff --git a/net/can/raw.c b/net/can/raw.c
> > index 3e9c893..0cfbc16 100644
> > --- a/net/can/raw.c
> > +++ b/net/can/raw.c
> > @@ -83,6 +83,7 @@ struct raw_sock {
> >  	int loopback;
> >  	int recv_own_msgs;
> >  	int fd_frames;
> > +	int recv_host_msgs;
> >  	int count;                 /* number of active filters */
> >  	struct can_filter dfilter; /* default/single filter */
> >  	struct can_filter *filter; /* pointer to filter(s) */
> > @@ -120,6 +121,10 @@ static void raw_rcv(struct sk_buff *oskb, void *data)
> >  	if (!ro->recv_own_msgs && oskb->sk == sk)
> >  		return;
> >  
> > +	/* check if we need to skip locally generated messages */
> > +	if (!ro->recv_host_msgs && oskb->sk)
> > +		return;
> > +
> >  	/* do not pass frames with DLC > 8 to a legacy socket */
> >  	if (!ro->fd_frames) {
> >  		struct canfd_frame *cfd = (struct canfd_frame *)oskb->data;
> > @@ -301,6 +306,7 @@ static int raw_init(struct sock *sk)
> >  	ro->loopback         = 1;
> >  	ro->recv_own_msgs    = 0;
> >  	ro->fd_frames        = 0;
> > +	ro->recv_host_msgs   = 1;
> >  
> >  	/* set notifier */
> >  	ro->notifier.notifier_call = raw_notifier;
> > @@ -588,6 +594,15 @@ static int raw_setsockopt(struct socket *sock, int level, int optname,
> >  
> >  		break;
> >  
> > +	case CAN_RAW_RECV_HOST_MSGS:
> > +		if (optlen != sizeof(ro->recv_host_msgs))
> > +			return -EINVAL;
> > +
> > +		if (copy_from_user(&ro->recv_host_msgs, optval, optlen))
> > +			return -EFAULT;
> > +
> > +		break;
> > +
> >  	default:
> >  		return -ENOPROTOOPT;
> >  	}
> > @@ -652,6 +667,12 @@ static int raw_getsockopt(struct socket *sock, int level, int optname,
> >  		val = &ro->fd_frames;
> >  		break;
> >  
> > +	case CAN_RAW_RECV_HOST_MSGS:
> > +		if (len > sizeof(int))
> > +			len = sizeof(int);
> > +		val = &ro->recv_host_msgs;
> > +		break;
> > +
> >  	default:
> >  		return -ENOPROTOOPT;
> >  	}
> 
> 
> -- 
> Kurt Van Dijck
> GRAMMER EiA ELECTRONICS
> http://www.eia.be
> kurt.van.dijck@eia.be
> +32-38708534

-- 
Kurt Van Dijck
GRAMMER EiA ELECTRONICS
http://www.eia.be
kurt.van.dijck@eia.be
+32-38708534

Re: loopback problem with BCM, RAW using, Daniele Venzano

[Oliver Hartkopp]

On 22.08.2012 10:57, Kurt Van Dijck wrote:

> Oliver,
> 
> I did not follow this thread in depth.
> 
> The patch looks minimal, but I doubt its usefullness.
> In a proper designed CAN system, each node uses distinct CAN-ids.
> Therefore, filtering out local traffic can always be accomplished
> with the current filtering (RTR frames are an exception, but are
> irrelevant here).
> 
> userspace can test flags (MSG_DONTROUTE) to decide if a received
> frame is from <localhost> or remote.
> So I don't see the problem that you're addressing with this patch.


Hello Kurt,

this was a quick shot.

After thinking a bit more on this idea, this sockopt is something like an
additional filter. But then i needs to have two bits:

- receive rx frames (from the outside)
- receive tx frames (from the local host)

Default is to receive both types of frames ...

Btw. i don't know if this additional sockopt makes it even more complicated
for users or if your suggestion to select the frames after reception in the
userspace is better.

Regards,
Oliver

ps. the CAN FD capable 'candump' now prints the RX/TX info on demand too.

Re: loopback problem with BCM, RAW using, Daniele Venzano

[Kurt Van Dijck]

On Thu, Aug 23, 2012 at 08:35:45PM +0200, Oliver Hartkopp wrote:
> On 22.08.2012 10:57, Kurt Van Dijck wrote:
> 
> > Oliver,
> > 
> > I did not follow this thread in depth.
> > 
> > The patch looks minimal, but I doubt its usefullness.
> > In a proper designed CAN system, each node uses distinct CAN-ids.
> > Therefore, filtering out local traffic can always be accomplished
> > with the current filtering (RTR frames are an exception, but are
> > irrelevant here).
> > 
> > userspace can test flags (MSG_DONTROUTE) to decide if a received
> > frame is from <localhost> or remote.
> > So I don't see the problem that you're addressing with this patch.
> 
> 
> Hello Kurt,
> 
> this was a quick shot.
> 
> After thinking a bit more on this idea, this sockopt is something like an
> additional filter. But then i needs to have two bits:
> 
> - receive rx frames (from the outside)
> - receive tx frames (from the local host)
> 
> Default is to receive both types of frames ...
> 
> Btw. i don't know if this additional sockopt makes it even more complicated
> for users ...

IMO, things get complicated.
Example: what should I get when
CAN_RAW_RECV_OWN_MSGS is set & CAN_RAW_RECV_HOST_MSGS is cleared?

> 
> Regards,
> Oliver
> 
> ps. the CAN FD capable 'candump' now prints the RX/TX info on demand too.
really nice.

-- 
Kurt Van Dijck
GRAMMER EiA ELECTRONICS
http://www.eia.be
kurt.van.dijck@eia.be
+32-38708534

Re: loopback problem with BCM, RAW using, Daniele Venzano

[Oliver Hartkopp]

On 24.08.2012 06:47, Kurt Van Dijck wrote:

> On Thu, Aug 23, 2012 at 08:35:45PM +0200, Oliver Hartkopp wrote:
>> On 22.08.2012 10:57, Kurt Van Dijck wrote:
>>
>>> Oliver,
>>>
>>> I did not follow this thread in depth.
>>>
>>> The patch looks minimal, but I doubt its usefullness.
>>> In a proper designed CAN system, each node uses distinct CAN-ids.
>>> Therefore, filtering out local traffic can always be accomplished
>>> with the current filtering (RTR frames are an exception, but are
>>> irrelevant here).
>>>
>>> userspace can test flags (MSG_DONTROUTE) to decide if a received
>>> frame is from <localhost> or remote.
>>> So I don't see the problem that you're addressing with this patch.
>>
>>
>> Hello Kurt,
>>
>> this was a quick shot.
>>
>> After thinking a bit more on this idea, this sockopt is something like an
>> additional filter. But then i needs to have two bits:
>>
>> - receive rx frames (from the outside)
>> - receive tx frames (from the local host)
>>
>> Default is to receive both types of frames ...
>>
>> Btw. i don't know if this additional sockopt makes it even more complicated
>> for users ...
> 
> IMO, things get complicated.
> Example: what should I get when
> CAN_RAW_RECV_OWN_MSGS is set & CAN_RAW_RECV_HOST_MSGS is cleared?


Yep. That was also my thought. And putting CAN_RAW_RECV_OWN_MSGS into the new
sockopt in some way is misleading too.

Your original proposal to use the per-socket CAN-ID filters that are already
in place seems the appropriate solution for Maheshs request.

Regards,
Oliver