Explicitly map PACKET_ values to LINUX_SLL_ values, so that even if a
future Linux kernel changes the PACKET_ values out from under us, the values recorded in the packet header in DLT_LINUX_SLL captures does *not* change. Don't map ETH_P_802_2 to the packet length, map it and ETH_P_802_3 to standardized LINUX_SLL_P_ values, so that even if a future Linux kernel changes the ETH_P_ values out from under us, the values recorded in the packet header in DLT_LINUX_SLL captures does *not* change, and so that you don't have to be running on Linux to be able to handle DLT_LINUX_SLL captures.
This commit is contained in:
guy
parent
db46beec77
commit
cf54e028ce
68
pcap-linux.c
68
pcap-linux.c
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@ -26,7 +26,7 @@
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*/
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#ifndef lint
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static const char rcsid[] =
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"@(#) $Header: /tcpdump/master/libpcap/pcap-linux.c,v 1.45 2000-12-22 11:53:27 guy Exp $ (LBL)";
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"@(#) $Header: /tcpdump/master/libpcap/pcap-linux.c,v 1.46 2000-12-22 12:11:36 guy Exp $ (LBL)";
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#endif
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/*
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@ -374,15 +374,65 @@ pcap_read_packet(pcap_t *handle, pcap_handler callback, u_char *userdata)
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packet_len += SLL_HDR_LEN;
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hdrp = (struct sll_header *)handle->buffer;
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hdrp->sll_pkttype = htons(from.sll_pkttype);
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if (from.sll_protocol == ETH_P_802_2) {
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/*
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* This is an 802.3 packet; set the packet type
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* field to the length, in network byte order.
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*/
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hdrp->sll_protocol = htons(packet_len);
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} else
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/*
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* Map the PACKET_ value to a LINUX_SLL_ value; we
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* want the same numerical value to be used in
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* the link-layer header even if the numerical values
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* for the PACKET_ #defines change, so that programs
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* that look at the packet type field will always be
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* able to handle DLT_LINUX_SLL captures.
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*/
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switch (from.sll_pktttype) {
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case PACKET_HOST:
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hdrp->sll_pkttype = htons(LINUX_SLL_HOST);
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break;
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case PACKET_BROADCAST:
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hdrp->sll_pkttype = htons(LINUX_SLL_BROADCAST);
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break;
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case PACKET_MULTICAST:
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hdrp->sll_pkttype = htons(LINUX_SLL_MULTICAST);
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break;
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case PACKET_OTHERHOST:
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hdrp->sll_pkttype = htons(LINUX_SLL_OTHERHOST);
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break;
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case PACKET_OUTGOING:
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hdrp->sll_pkttype = htons(LINUX_SLL_OUTGOING);
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break;
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default:
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hdrp->sll_pkttype = -1;
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break;
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}
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/*
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* Map special Linux internal protocol types to
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* LINUX_SLL_P_ values; we want the same numerical
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* value to be used in the link-layer header even
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* if the numerical values for the ETH_P_ #defines
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* change, so that programs that look at the protocol
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* field will always be able to handle DLT_LINUX_SLL
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* captures.
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*/
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switch (ntohs(from.sll_protocol)) {
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case ETH_P_802_2:
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hdrp->sll_protocol = ntohs(LINUX_SLL_P_802_2);
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break;
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case ETH_P_802_3:
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hdrp->sll_protocol = ntohs(LINUX_SLL_P_802_3);
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break;
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default:
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hdrp->sll_protocol = from.sll_protocol;
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break;
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}
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hdrp->sll_hatype = htons(from.sll_hatype);
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hdrp->sll_halen = htons(from.sll_halen);
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memcpy(hdrp->sll_addr, from.sll_addr,
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20
sll.h
20
sll.h
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@ -35,7 +35,7 @@
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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/Attic/sll.h,v 1.1 2000-12-21 10:29:24 guy Exp $ (LBL)
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* @(#) $Header: /tcpdump/master/libpcap/Attic/sll.h,v 1.2 2000-12-22 12:11:36 guy Exp $ (LBL)
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*/
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/*
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@ -77,13 +77,23 @@ struct sll_header {
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};
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/*
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* The LINUX_SLL_ values; they are defined here so that they're available
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* even on systems other than Linux, but they should be given the same
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* values as the corresponding PACKET_ values on Linux. (Let's hope
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* those values never change.)
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* The LINUX_SLL_ values for "sll_pkttype"; these correspond to the
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* PACKET_ values on Linux, but are defined here so that they're
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* available even on systems other than Linux, and so that they
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* don't change even if the PACKET_ values change.
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*/
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#define LINUX_SLL_HOST 0
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#define LINUX_SLL_BROADCAST 1
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#define LINUX_SLL_MULTICAST 2
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#define LINUX_SLL_OTHERHOST 3
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#define LINUX_SLL_OUTGOING 4
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/*
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* The LINUX_SLL_ values for "sll_protocol"; these correspond to the
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* ETH_P_ values on Linux, but are defined here so that they're
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* available even on systems other than Linux, and so that they
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* don't change even if the ETH_P_ values change.
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*/
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#define LINUX_SLL_P_802_3 0x0001 /* Novell 802.3 frames without 802.2 LLC header */
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#define LINUX_SLL_P_802_2 0x0004 /* 802.2 frames (not D/I/X Ethernet) */
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