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Message-Id: <1306366595-731-1-git-send-email-greearb@candelatech.com>
Date: Wed, 25 May 2011 16:36:35 -0700
From: greearb@...delatech.com
To: netdev@...r.kernel.org
Cc: Ben Greear <greearb@...delatech.com>
Subject: [PATCH] af-packet: Add flag to distinguish VID 0 from no-vlan.
From: Ben Greear <greearb@...delatech.com>
Currently, user-space cannot determine if a 0 tcp_vlan_tci
means there is no VLAN tag or the VLAN ID was zero.
Add flag to make this explicit. User-space can check for
TP_STATUS_VLAN_VALID || tp_vlan_tci > 0, which will be backwards
compatible. Older could would have just checked for tp_vlan_tci,
so it will work no worse than before.
Signed-off-by: Ben Greear <greearb@...delatech.com>
---
:100644 100644 72bfa5a... 6d66ce1... M include/linux/if_packet.h
:100644 100644 658edd1... 885d76d... M net/packet/af_packet.c
include/linux/if_packet.h | 1 +
net/packet/af_packet.c | 7 ++++++-
2 files changed, 7 insertions(+), 1 deletions(-)
diff --git a/include/linux/if_packet.h b/include/linux/if_packet.h
index 72bfa5a..6d66ce1 100644
--- a/include/linux/if_packet.h
+++ b/include/linux/if_packet.h
@@ -70,6 +70,7 @@ struct tpacket_auxdata {
#define TP_STATUS_COPY 0x2
#define TP_STATUS_LOSING 0x4
#define TP_STATUS_CSUMNOTREADY 0x8
+#define TP_STATUS_VLAN_VALID 0x10 /* auxdata has valid tp_vlan_tci */
/* Tx ring - header status */
#define TP_STATUS_AVAILABLE 0x0
diff --git a/net/packet/af_packet.c b/net/packet/af_packet.c
index 658edd1..885d76d 100644
--- a/net/packet/af_packet.c
+++ b/net/packet/af_packet.c
@@ -1772,7 +1772,12 @@ static int packet_recvmsg(struct kiocb *iocb, struct socket *sock,
aux.tp_snaplen = skb->len;
aux.tp_mac = 0;
aux.tp_net = skb_network_offset(skb);
- aux.tp_vlan_tci = vlan_tx_tag_get(skb);
+ if (vlan_tx_tag_present(skb)) {
+ aux.tp_vlan_tci = vlan_tx_tag_get(skb);
+ aux.tp_status |= TP_STATUS_VLAN_VALID;
+ }
+ else
+ aux.tp_vlan_tci = 0;
put_cmsg(msg, SOL_PACKET, PACKET_AUXDATA, sizeof(aux), &aux);
}
--
1.7.3.4
--
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