On Thu, 6 Dec 2012, Michael Richardson wrote:
> Date: Thu, 6 Dec 2012 17:59:13
> From: Michael Richardson <m...@sandelman.ca>
> To: Eric W. Biederman <ebied...@xmission.com>
> Cc: a...@aristanetworks.com, tcpdump-workers@lists.tcpdump.org,
> net...@vger.kernel.org, Francesco Ruggeri <frugg...@aristanetworks.com>
> Subject: Re: [tcpdump-workers] vlan tagged packets and libpcap breakage
>
>
> >>>>> "Eric" == Eric W Biederman <ebied...@xmission.com> writes:
> Eric> It is a bit odd that you are indenting with spaces instead of tabs
> Eric> in a file that is indented with tab. Again libpcap isn't my code
> so I
> Eric> don't care but someone else might.
Here's an updated patch. I have converted spaces to tabs consistent with
rest of the file. I have also set up github and sent a pull request
:
commit b977ebd9d9608bb8a8e4927e7a6286bdfd6b94a8
Author: Ani Sinha <a...@aristanetworks.com>
Date: Mon Dec 10 14:58:15 2012 -0800
Linux kernel 3.0 uses TP_STATUS_VLAN_VALID flag in packet
auxilliary data aux->tp_status to indicate a packet tagged
with a valid vlan ID 0 with another packet that is not
vlan tagged. Use this flag to check for the presence of
a vlan tagged packet. Also be careful not to cause any
breakage when libpcap is compiled against a newer kernel
(>=3.0) and used on top of an older kernel that does not
use this flag.
Signed-off-by: Ani Sinha <a...@aristanetworks.com>
diff --git a/pcap-linux.c b/pcap-linux.c
index a42c3ac..ffcabdf 100644
--- a/pcap-linux.c
+++ b/pcap-linux.c
@@ -133,6 +133,7 @@ static const char rcsid[] _U_ =
#include <sys/utsname.h>
#include <sys/mman.h>
#include <linux/if.h>
+#include <linux/if_packet.h>
#include <netinet/in.h>
#include <linux/if_ether.h>
#include <net/if_arp.h>
@@ -1543,7 +1544,13 @@ pcap_read_packet(pcap_t *handle, pcap_handler callback,
u_char *userdata)
continue;
aux = (struct tpacket_auxdata *)CMSG_DATA(cmsg);
- if (aux->tp_vlan_tci == 0)
+#if defined(TP_STATUS_VLAN_VALID)
+ if ((aux->tp_vlan_tci == 0) && !(aux->tp_status &
TP_STATUS_VLAN_VALID))
+#else
+ if (aux->tp_vlan_tci == 0) /* this is ambigious but
without the
+ TP_STATUS_VLAN_VALID flag,
there is
+ nothing that we can do */
+#endif
continue;
len = packet_len > iov.iov_len ? iov.iov_len :
packet_len;
@@ -3936,7 +3943,12 @@ pcap_read_linux_mmap(pcap_t *handle, int max_packets,
pcap_handler callback,
}
#ifdef HAVE_TPACKET2
- if (handle->md.tp_version == TPACKET_V2 && h.h2->tp_vlan_tci &&
+ if ((handle->md.tp_version == TPACKET_V2) &&
+#if defined(TP_STATUS_VLAN_VALID)
+ (h.h2->tp_vlan_tci || (h.h2->tp_status & TP_STATUS_VLAN_VALID))
&&
+#else
+ h.h2->tp_vlan_tci &&
+#endif
handle->md.vlan_offset != -1 &&
tp_snaplen >= (unsigned int) handle->md.vlan_offset) {
struct vlan_tag *tag;
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