Attachment 302587 Details for Bug 441446 – don't double-count received packets

[patch] don't double-count received packets

libpcap-0.9.4-packetstats.patch (text/plain), 4.88 KB, created by Miroslav Lichvar on 2008-04-16 12:02:49 UTC

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Creator: Miroslav Lichvar

Created: 2008-04-16 12:02:49 UTC

Size: 4.88 KB

patch

obsolete

>Index: libpcap/pcap-int.h
>===================================================================
>RCS file: /tcpdump/master/libpcap/pcap-int.h,v
>retrieving revision 1.68.2.6
>retrieving revision 1.68.2.7
>diff -u -r1.68.2.6 -r1.68.2.7
>--- libpcap/pcap-int.h	7 Jul 2005 06:56:04 -0000	1.68.2.6
>+++ libpcap/pcap-int.h	24 Nov 2005 19:28:23 -0000	1.68.2.7
>@@ -30,7 +30,7 @@
>  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
>  * SUCH DAMAGE.
>  *
>- * @(#) $Header: /tcpdump/master/libpcap/pcap-int.h,v 1.68.2.6 2005/07/07 06:56:04 guy Exp $ (LBL)
>+ * @(#) $Header: /tcpdump/master/libpcap/pcap-int.h,v 1.68.2.7 2005/11/24 19:28:23 guy Exp $ (LBL)
>  */
> 
> #ifndef pcap_int_h
>@@ -88,6 +88,7 @@
> 	int	ifindex;	/* interface index of device we're bound to */
> 	int	lo_ifindex;	/* interface index of the loopback device */
> 	struct pcap *next;	/* list of open promiscuous sock_packet pcaps */
>+	u_int	packets_read;	/* count of packets read with recvfrom() */
> #endif
> 
> #ifdef HAVE_DAG_API
>Index: libpcap/pcap-linux.c
>===================================================================
>RCS file: /tcpdump/master/libpcap/pcap-linux.c,v
>retrieving revision 1.110.2.7
>retrieving revision 1.110.2.8
>diff -u -r1.110.2.7 -r1.110.2.8
>--- libpcap/pcap-linux.c	8 Oct 2005 11:31:16 -0000	1.110.2.7
>+++ libpcap/pcap-linux.c	24 Nov 2005 19:28:23 -0000	1.110.2.8
>@@ -704,8 +704,18 @@
> 	 * here, but it's not clear that always incrementing
> 	 * the count is more expensive than always testing a flag
> 	 * in memory.
>+	 *
>+	 * We keep the count in "md.packets_read", and use that for
>+	 * "ps_recv" if we can't get the statistics from the kernel.
>+	 * We do that because, if we *can* get the statistics from
>+	 * the kernel, we use "md.stat.ps_recv" and "md.stat.ps_drop"
>+	 * as running counts, as reading the statistics from the
>+	 * kernel resets the kernel statistics, and if we directly
>+	 * increment "md.stat.ps_recv" here, that means it will
>+	 * count packets *twice* on systems where we can get kernel
>+	 * statistics - once here, and once in pcap_stats_linux().
> 	 */
>-	handle->md.stat.ps_recv++;
>+	handle->md.packets_read++;
> 
> 	/* Call the user supplied callback function */
> 	callback(userdata, &pcap_header, bp);
>@@ -853,8 +863,14 @@
> 	 *
> 	 *	"ps_recv" doesn't include packets not yet read from
> 	 *	the kernel by libpcap.
>+	 *
>+	 * We maintain the count of packets processed by libpcap in
>+	 * "md.packets_read", for reasons described in the comment
>+	 * at the end of pcap_read_packet().  We have no idea how many
>+	 * packets were dropped.
> 	 */
>-	*stats = handle->md.stat;
>+	stats->ps_recv = handle->md.packets_read;
>+	stats->ps_drop = 0;
> 	return 0;
> }
> 
>Index: libpcap/pcap-linux.c
>===================================================================
>RCS file: /tcpdump/master/libpcap/pcap-linux.c,v
>retrieving revision 1.110.2.9
>retrieving revision 1.110.2.10
>diff -u -r1.110.2.9 -r1.110.2.10
>--- libpcap/pcap-linux.c	22 Jan 2006 20:12:09 -0000	1.110.2.9
>+++ libpcap/pcap-linux.c	23 Feb 2006 07:35:35 -0000	1.110.2.10
>@@ -789,6 +789,23 @@
> 	if (getsockopt(handle->fd, SOL_PACKET, PACKET_STATISTICS,
> 			&kstats, &len) > -1) {
> 		/*
>+		 * On systems where the PACKET_STATISTICS "getsockopt()"
>+		 * argument is supported on PF_PACKET sockets:
>+		 *
>+		 *	"ps_recv" counts only packets that *passed* the
>+		 *	filter, not packets that didn't pass the filter.
>+		 *	This includes packets later dropped because we
>+		 *	ran out of buffer space.
>+		 *
>+		 *	"ps_drop" counts packets dropped because we ran
>+		 *	out of buffer space.  It doesn't count packets
>+		 *	dropped by the interface driver.  It counts only
>+		 *	packets that passed the filter.
>+		 *
>+		 *	Both statistics include packets not yet read from
>+		 *	the kernel by libpcap, and thus not yet seen by
>+		 *	the application.
>+		 *
> 		 * In "linux/net/packet/af_packet.c", at least in the
> 		 * 2.4.9 kernel, "tp_packets" is incremented for every
> 		 * packet that passes the packet filter *and* is
>@@ -818,6 +835,8 @@
> 		 */
> 		handle->md.stat.ps_recv += kstats.tp_packets;
> 		handle->md.stat.ps_drop += kstats.tp_drops;
>+		*stats = handle->md.stat;
>+		return 0;
> 	}
> 	else
> 	{
>@@ -837,21 +856,6 @@
> #endif
> 	/*
> 	 * On systems where the PACKET_STATISTICS "getsockopt()" argument
>-	 * is supported on PF_PACKET sockets:
>-	 *
>-	 *	"ps_recv" counts only packets that *passed* the filter,
>-	 *	not packets that didn't pass the filter.  This includes
>-	 *	packets later dropped because we ran out of buffer space.
>-	 *
>-	 *	"ps_drop" counts packets dropped because we ran out of
>-	 *	buffer space.  It doesn't count packets dropped by the
>-	 *	interface driver.  It counts only packets that passed
>-	 *	the filter.
>-	 *
>-	 *	Both statistics include packets not yet read from the
>-	 *	kernel by libpcap, and thus not yet seen by the application.
>-	 *
>-	 * On systems where the PACKET_STATISTICS "getsockopt()" argument
> 	 * is not supported on PF_PACKET sockets:
> 	 *
> 	 *	"ps_recv" counts only packets that *passed* the filter,

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