tcpdump mailing list archives
Re: vlan tagged packets and libpcap breakage
From: Ani Sinha <ani () aristanetworks com>
Date: Thu, 6 Dec 2012 13:22:08 -0800
On Sat, Nov 17, 2012 at 3:33 PM, Eric W. Biederman <ebiederm () xmission com> wrote:
the vlan header in packets as we receive them. The code is correct except for the case of packets in vlan 0. Currently the packet reconstruction is ambiguous. The most recent kernels have a TP_STATUS_VLAN_VALID flag that can be checked to see if the packet was in vlan 0 or if there was no vlan at all. libpcap probably should be taught how to handle TP_STATUS_VLAN_VALID so that it can get the vlan 0 handling correct.
May be this? Index: libpcap-1.1.1/pcap-linux.c =================================================================== --- libpcap-1.1.1.orig/pcap-linux.c +++ libpcap-1.1.1/pcap-linux.c @@ -132,6 +132,7 @@ 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> @@ -1486,7 +1487,13 @@ pcap_read_packet(pcap_t *handle, pcap_ha 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 & 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; @@ -3565,7 +3555,11 @@ pcap_read_linux_mmap(pcap_t *handle, int } #ifdef HAVE_TPACKET2 - if (handle->md.tp_version == TPACKET_V2 && h.h2->tp_vlan_tci && +#if defined(TP_STATUS_VLAN_VALID) + if (handle->md.tp_version == TPACKET_V2 && (h.h2->tp_vlan_tci & TP_STATUS_VLAN_VALID) && +#else + if (handle->md.tp_version == TPACKET_V2 && h.h2->tp_vlan_tci && +#endif handle->md.vlan_offset != -1 && tp_snaplen >= (unsigned int) handle->md.vlan_offset) { struct vlan_tag *tag; _______________________________________________ tcpdump-workers mailing list tcpdump-workers () lists tcpdump org https://lists.sandelman.ca/mailman/listinfo/tcpdump-workers
Current thread:
- Re: vlan tagged packets and libpcap breakage, (continued)
- Re: vlan tagged packets and libpcap breakage Ani Sinha (Oct 31)
- Re: vlan tagged packets and libpcap breakage Ani Sinha (Dec 06)
- Re: vlan tagged packets and libpcap breakage Bill Fenner (Nov 11)
- Re: vlan tagged packets and libpcap breakage Ani Sinha (Nov 13)
- Re: vlan tagged packets and libpcap breakage Ani Sinha (Nov 13)
- Re: vlan tagged packets and libpcap breakage Michael Richardson (Nov 14)
- Re: vlan tagged packets and libpcap breakage Eric W. Biederman (Nov 18)
- Message not available
- Re: vlan tagged packets and libpcap breakage Daniel Borkmann (Nov 18)
- Re: vlan tagged packets and libpcap breakage Eric W. Biederman (Nov 18)
- Message not available
- Re: vlan tagged packets and libpcap breakage Eric W. Biederman (Nov 18)
- Re: vlan tagged packets and libpcap breakage Ani Sinha (Dec 06)
- Re: vlan tagged packets and libpcap breakage Eric W. Biederman (Dec 06)
- Re: vlan tagged packets and libpcap breakage Ani Sinha (Dec 06)
- Re: vlan tagged packets and libpcap breakage Ani Sinha (Dec 06)
- Re: vlan tagged packets and libpcap breakage Eric W. Biederman (Dec 06)
- Re: vlan tagged packets and libpcap breakage Ani Sinha (Dec 06)
- Re: vlan tagged packets and libpcap breakage Ani Sinha (Dec 06)
- Re: vlan tagged packets and libpcap breakage Eric W. Biederman (Dec 06)
- Re: vlan tagged packets and libpcap breakage Michael Richardson (Dec 06)
- Re: vlan tagged packets and libpcap breakage Ani Sinha (Dec 10)
- Re: vlan tagged packets and libpcap breakage Ani Sinha (Dec 11)