From Patrick McHardy:
VLAN packets sent over devices supporting VLAN tagging/stripping in hardware don't have a VLAN header when they are received on packet sockets. The VLAN TCI is available through the PACKET_AUXDATA cmsg, reconstruct the entire header when necessary.
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guy
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@ -17,7 +17,7 @@
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# WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED WARRANTIES OF
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# MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
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#
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# @(#) $Header: /tcpdump/master/libpcap/Makefile.in,v 1.125 2008-05-30 01:35:33 guy Exp $ (LBL)
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# @(#) $Header: /tcpdump/master/libpcap/Makefile.in,v 1.126 2008-08-06 07:45:00 guy Exp $ (LBL)
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#
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# Various configurable paths (remember to edit Makefile.in, not Makefile)
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@ -102,6 +102,7 @@ HDR = \
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pcap/pcap.h \
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pcap/sll.h \
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pcap/usb.h \
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pcap/vlan.h \
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pcap.h \
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pcap-int.h \
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pcap-namedb.h \
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61
pcap-linux.c
61
pcap-linux.c
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@ -34,7 +34,7 @@
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#ifndef lint
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static const char rcsid[] _U_ =
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"@(#) $Header: /tcpdump/master/libpcap/pcap-linux.c,v 1.151 2008-08-06 07:39:44 guy Exp $ (LBL)";
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"@(#) $Header: /tcpdump/master/libpcap/pcap-linux.c,v 1.152 2008-08-06 07:45:00 guy Exp $ (LBL)";
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#endif
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/*
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@ -108,6 +108,7 @@ static const char rcsid[] _U_ =
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#include "pcap-int.h"
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#include "pcap/sll.h"
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#include "pcap/vlan.h"
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#ifdef HAVE_DAG_API
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#include "pcap-dag.h"
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@ -165,6 +166,9 @@ static const char rcsid[] _U_ =
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*/
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# ifdef PACKET_HOST
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# define HAVE_PF_PACKET_SOCKETS
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# ifdef PACKET_AUXDATA
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# define HAVE_PACKET_AUXDATA
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# endif /* PACKET_AUXDATA */
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# endif /* PACKET_HOST */
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@ -629,6 +633,11 @@ pcap_read_packet(pcap_t *handle, pcap_handler callback, u_char *userdata)
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struct pcap_pkthdr pcap_header;
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struct iovec iov;
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struct msghdr msg;
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struct cmsghdr *cmsg;
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union {
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struct cmsghdr cmsg;
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char buf[CMSG_SPACE(sizeof(struct tpacket_auxdata))];
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} cmsg_buf;
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#ifdef HAVE_PF_PACKET_SOCKETS
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/*
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* If this is a cooked device, leave extra room for a
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@ -667,8 +676,8 @@ pcap_read_packet(pcap_t *handle, pcap_handler callback, u_char *userdata)
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msg.msg_namelen = sizeof(from);
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msg.msg_iov = &iov;
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msg.msg_iovlen = 1;
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msg.msg_control = NULL;
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msg.msg_controllen = 0;
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msg.msg_control = &cmsg_buf;
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msg.msg_controllen = sizeof(cmsg_buf);
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msg.msg_flags = 0;
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iov.iov_len = handle->bufsize - offset;
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@ -774,6 +783,36 @@ pcap_read_packet(pcap_t *handle, pcap_handler callback, u_char *userdata)
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from.sll_halen);
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hdrp->sll_protocol = from.sll_protocol;
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}
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#ifdef HAVE_PACKET_AUXDATA
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for (cmsg = CMSG_FIRSTHDR(&msg); cmsg; cmsg = CMSG_NXTHDR(&msg, cmsg)) {
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struct tpacket_auxdata *aux;
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unsigned int len;
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struct vlan_tag *tag;
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if (cmsg->cmsg_len < CMSG_LEN(sizeof(struct tpacket_auxdata)) ||
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cmsg->cmsg_level != SOL_PACKET ||
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cmsg->cmsg_type != PACKET_AUXDATA)
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continue;
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aux = (struct tpacket_auxdata *)CMSG_DATA(cmsg);
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if (aux->tp_vlan_tci == 0)
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continue;
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len = packet_len > iov.iov_len ? iov.iov_len : packet_len;
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if (len < 2 * ETH_ALEN)
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break;
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bp -= VLAN_TAG_LEN;
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memmove(bp, bp + VLAN_TAG_LEN, 2 * ETH_ALEN);
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tag = (struct vlan_tag *)(bp + 2 * ETH_ALEN);
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tag->vlan_tpid = htons(ETH_P_8021Q);
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tag->vlan_tci = htons(aux->tp_vlan_tci);
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packet_len += VLAN_TAG_LEN;
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}
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#endif /* HAVE_PACKET_AUXDATA */
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#endif
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/*
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@ -1591,7 +1630,7 @@ static int
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activate_new(pcap_t *handle)
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{
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#ifdef HAVE_PF_PACKET_SOCKETS
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int sock_fd = -1, arptype;
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int sock_fd = -1, arptype, val;
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int err = 0;
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struct packet_mreq mr;
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const char* device = handle->opt.source;
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@ -1802,6 +1841,20 @@ activate_new(pcap_t *handle)
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}
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}
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/* Enable auxillary data if supported and reserve room for
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* reconstructing VLAN headers. */
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#ifdef HAVE_PACKET_AUXDATA
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val = 1;
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if (setsockopt(sock_fd, SOL_PACKET, PACKET_AUXDATA, &val,
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sizeof(val)) == -1 && errno != ENOPROTOOPT) {
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snprintf(handle->errbuf, PCAP_ERRBUF_SIZE,
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"setsockopt: %s", pcap_strerror(errno));
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close(sock_fd);
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return PCAP_ERROR;
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}
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handle->offset += VLAN_TAG_LEN;
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#endif /* HAVE_PACKET_AUXDATA */
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/*
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* This is a 2.2[.x] or later kernel (we know that
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* because we're not using a SOCK_PACKET socket -
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@ -0,0 +1,46 @@
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/*-
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* Copyright (c) 1990, 1991, 1992, 1993, 1994, 1995, 1996, 1997
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* The Regents of the University of California. All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 3. All advertising materials mentioning features or use of this software
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* must display the following acknowledgement:
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* This product includes software developed by the University of
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* California, Berkeley and its contributors.
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* 4. Neither the name of the University nor the names of its contributors
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* may be used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*
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* @(#) $Header: /tcpdump/master/libpcap/pcap/vlan.h,v 1.1 2008-08-06 07:45:00 guy Exp $
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*/
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#ifndef lib_pcap_vlan_h
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#define lib_pcap_vlan_h
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struct vlan_tag {
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u_int16_t vlan_tpid; /* ETH_P_8021Q */
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u_int16_t vlan_tci; /* VLAN TCI */
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};
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#define VLAN_TAG_LEN 4
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#endif
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