[PATCH nft v2] src: netlink: Subscribe nft monitor and nft monitor trace to respective groups.

[PATCH nft v2] src: netlink: Subscribe nft monitor and nft monitor trace to respective groups.

[Varsha Rao]

Subscribe nft monitor to both NFNLGRP_NFTABLES and NFNLGRP_NFTRACE.
nft monitor trace subscribes only to NFNLGRP_NFTRACE. Other event
reporting options to only NFNLGRP_NFTABLES.

Signed-off-by: Varsha Rao <rvarsha016@gmail.com>
---
Changes in v1:
- Subscribe nft monitor to only _NFTABLES.
- Subsribe nft monitor trace to only _NFTRACE.

Changes in v2:
- Subsribe nft monitor to both _NFTABLES and _NFTRACE.
- Subscribe other events to _NFTABLES.
- Modified commit message.

 src/netlink.c | 35 ++++++++++++++++++++++++-----------
 1 file changed, 24 insertions(+), 11 deletions(-)

diff --git a/src/netlink.c b/src/netlink.c
index 9cef4c4..f7069fd 100644
--- a/src/netlink.c
+++ b/src/netlink.c
@@ -3078,21 +3078,34 @@ static int netlink_events_cb(const struct nlmsghdr *nlh, void *data)
 int netlink_monitor(struct netlink_mon_handler *monhandler,
 		     struct mnl_socket *nf_sock)
 {
-	int group;
-
-	group = NFNLGRP_NFTABLES;
-	if (mnl_socket_setsockopt(nf_sock, NETLINK_ADD_MEMBERSHIP, &group,
-				  sizeof(int)) < 0)
-		return netlink_io_error(monhandler->ctx, monhandler->loc,
+	int group = NFNLGRP_NFTRACE, val;
+
+	val = monhandler->monitor_flags | NFNLGRP_NFTABLES;
+	if (val == 131439) {
+		if (mnl_socket_setsockopt(nf_sock, NETLINK_ADD_MEMBERSHIP,
+					&group, sizeof(int)) < 0)
+			return netlink_io_error(monhandler->ctx,
+					monhandler->loc,
 					"Could not bind to netlink socket %s",
 					strerror(errno));
-
-	group = NFNLGRP_NFTRACE;
-	if (mnl_socket_setsockopt(nf_sock, NETLINK_ADD_MEMBERSHIP, &group,
-				  sizeof(int)) < 0)
-		return netlink_io_error(monhandler->ctx, monhandler->loc,
+	} else {
+		if (val < 0) {
+			if (mnl_socket_setsockopt(nf_sock,
+						NETLINK_ADD_MEMBERSHIP, &group,
+						sizeof(int)) < 0)
+				return netlink_io_error(monhandler->ctx,
+						monhandler->loc,
+						"Could not bind to netlink socket %s",
+						strerror(errno));
+		}
+		group = NFNLGRP_NFTABLES;
+		if (mnl_socket_setsockopt(nf_sock, NETLINK_ADD_MEMBERSHIP,
+					&group, sizeof(int)) < 0)
+			return netlink_io_error(monhandler->ctx,
+					monhandler->loc,
 					"Could not bind to netlink socket %s",
 					strerror(errno));
+	}
 
 	return mnl_nft_event_listener(nf_sock, netlink_events_cb,
 				      monhandler);
-- 
2.9.4

Re: [PATCH nft v2] src: netlink: Subscribe nft monitor and nft monitor trace to respective groups.

[Pablo Neira Ayuso]

On Fri, Jul 28, 2017 at 10:55:21AM +0530, Varsha Rao wrote:
> Subscribe nft monitor to both NFNLGRP_NFTABLES and NFNLGRP_NFTRACE.
> nft monitor trace subscribes only to NFNLGRP_NFTRACE. Other event
> reporting options to only NFNLGRP_NFTABLES.
> 
> Signed-off-by: Varsha Rao <rvarsha016@gmail.com>
> ---
> Changes in v1:
> - Subscribe nft monitor to only _NFTABLES.
> - Subsribe nft monitor trace to only _NFTRACE.
> 
> Changes in v2:
> - Subsribe nft monitor to both _NFTABLES and _NFTRACE.
> - Subscribe other events to _NFTABLES.
> - Modified commit message.
> 
>  src/netlink.c | 35 ++++++++++++++++++++++++-----------
>  1 file changed, 24 insertions(+), 11 deletions(-)
> 
> diff --git a/src/netlink.c b/src/netlink.c
> index 9cef4c4..f7069fd 100644
> --- a/src/netlink.c
> +++ b/src/netlink.c
> @@ -3078,21 +3078,34 @@ static int netlink_events_cb(const struct nlmsghdr *nlh, void *data)
>  int netlink_monitor(struct netlink_mon_handler *monhandler,
>  		     struct mnl_socket *nf_sock)
>  {
> -	int group;
> -
> -	group = NFNLGRP_NFTABLES;
> -	if (mnl_socket_setsockopt(nf_sock, NETLINK_ADD_MEMBERSHIP, &group,
> -				  sizeof(int)) < 0)
> -		return netlink_io_error(monhandler->ctx, monhandler->loc,
> +	int group = NFNLGRP_NFTRACE, val;
> +
> +	val = monhandler->monitor_flags | NFNLGRP_NFTABLES;
> +	if (val == 131439) {

What is this magic number?

Please, express this via some definition, so we don't have to remember
the meaning of magic number, it's good to make software more
maintainable.

Thanks.