*/
#ifndef lint
static const char rcsid[] =
- "@(#) $Header: /tcpdump/master/libpcap/gencode.c,v 1.160.2.2 2002-04-07 00:05:12 guy Exp $ (LBL)";
+ "@(#) $Header: /tcpdump/master/libpcap/gencode.c,v 1.160.2.4 2002-06-01 23:23:20 guy Exp $ (LBL)";
#endif
#ifdef HAVE_CONFIG_H
#include <sys/param.h>
#endif
-struct mbuf;
-struct rtentry;
+struct mbuf; /* Squelch compiler warnings on some platforms for */
+struct rtentry; /* declarations in <net/if.h> */
#include <net/if.h>
#include <netinet/in.h>
static pcap_t *bpf_pcap;
/* Hack for updating VLAN offsets. */
-static u_int orig_linktype = -1, orig_nl = -1;
+static u_int orig_linktype = -1, orig_nl = -1, orig_nl_nosnap = -1;
/* XXX */
#ifdef PCAP_FDDIPAD
/*
* Various code constructs need to know the layout of the data link
- * layer. These variables give the necessary offsets. off_linktype
- * is set to -1 for no encapsulation, in which case, IP is assumed.
+ * layer. These variables give the necessary offsets.
+ */
+
+/*
+ * "off_linktype" is the offset to information in the link-layer header
+ * giving the packet type.
+ *
+ * For Ethernet, it's the offset of the Ethernet type field.
+ *
+ * For link-layer types that always use 802.2 headers, it's the
+ * offset of the LLC header.
+ *
+ * For PPP, it's the offset of the PPP type field.
+ *
+ * For Cisco HDLC, it's the offset of the CHDLC type field.
+ *
+ * For BSD loopback, it's the offset of the AF_ value.
+ *
+ * For Linux cooked sockets, it's the offset of the type field.
+ *
+ * It's set to -1 for no encapsulation, in which case, IP is assumed.
*/
static u_int off_linktype;
+
+/*
+ * These are offsets to the beginning of the network-layer header.
+ *
+ * If the link layer never uses 802.2 LLC:
+ *
+ * "off_nl" and "off_nl_nosnap" are the same.
+ *
+ * If the link layer always uses 802.2 LLC:
+ *
+ * "off_nl" is the offset if there's a SNAP header following
+ * the 802.2 header;
+ *
+ * "off_nl_nosnap" is the offset if there's no SNAP header.
+ *
+ * If the link layer is Ethernet:
+ *
+ * "off_nl" is the offset if the packet is an Ethernet II packet
+ * (we assume no 802.3+802.2+SNAP);
+ *
+ * "off_nl_nosnap" is the offset if the packet is an 802.3 packet
+ * with an 802.2 header following it.
+ */
static u_int off_nl;
+static u_int off_nl_nosnap;
+
static int linktype;
static void
orig_linktype = -1;
orig_nl = -1;
+ orig_nl_nosnap = -1;
switch (type) {
case DLT_ARCNET:
off_linktype = 2;
off_nl = 6; /* XXX in reality, variable! */
+ off_nl_nosnap = 6; /* no 802.2 LLC */
return;
case DLT_EN10MB:
off_linktype = 12;
- off_nl = 14;
+ off_nl = 14; /* Ethernet II */
+ off_nl_nosnap = 17; /* 802.3+802.2 */
return;
case DLT_SLIP:
*/
off_linktype = -1;
off_nl = 16;
+ off_nl_nosnap = 16; /* no 802.2 LLC */
return;
case DLT_SLIP_BSDOS:
off_linktype = -1;
/* XXX end */
off_nl = 24;
+ off_nl_nosnap = 24; /* no 802.2 LLC */
return;
case DLT_NULL:
case DLT_LOOP:
off_linktype = 0;
off_nl = 4;
+ off_nl_nosnap = 4; /* no 802.2 LLC */
return;
case DLT_PPP:
case DLT_PPP_SERIAL: /* NetBSD sync/async serial PPP */
off_linktype = 2;
off_nl = 4;
+ off_nl_nosnap = 4; /* no 802.2 LLC */
return;
case DLT_PPP_ETHER:
*/
off_linktype = 6;
off_nl = 8;
+ off_nl_nosnap = 8; /* no 802.2 LLC */
return;
case DLT_PPP_BSDOS:
off_linktype = 5;
off_nl = 24;
+ off_nl_nosnap = 24; /* no 802.2 LLC */
return;
case DLT_FDDI:
#ifdef PCAP_FDDIPAD
off_linktype += pcap_fddipad;
#endif
- off_nl = 21;
+ off_nl = 21; /* FDDI+802.2+SNAP */
+ off_nl_nosnap = 16; /* FDDI+802.2 */
#ifdef PCAP_FDDIPAD
off_nl += pcap_fddipad;
+ off_nl_nosnap += pcap_fddipad;
#endif
return;
* 8 - figure out which byte that is).
*/
off_linktype = 14;
- off_nl = 22;
+ off_nl = 22; /* Token Ring+802.2+SNAP */
+ off_nl_nosnap = 17; /* Token Ring+802.2 */
return;
case DLT_IEEE802_11:
* data frames in networks with no bridges.
*/
off_linktype = 24;
- off_nl = 30;
+ off_nl = 32; /* 802.11+802.2+SNAP */
+ off_nl_nosnap = 27; /* 802.22+802.2 */
return;
case DLT_PRISM_HEADER:
* the Prism header is fixed-length.
*/
off_linktype = 144+24;
- off_nl = 144+30;
+ off_nl = 144+32; /* Prism+802.11+802.2+SNAP */
+ off_nl_nosnap = 144+27; /* Prism+802.11+802.2 */
return;
case DLT_ATM_RFC1483:
+ case DLT_ATM_CLIP: /* Linux ATM defines this */
/*
* assume routed, non-ISO PDUs
* (i.e., LLC = 0xAA-AA-03, OUT = 0x00-00-00)
*/
- off_linktype = 6;
- off_nl = 8;
+ off_linktype = 0;
+ off_nl = 8; /* 802.2+SNAP */
+ off_nl_nosnap = 3; /* 802.2 */
return;
case DLT_RAW:
off_linktype = -1;
off_nl = 0;
- return;
-
- case DLT_ATM_CLIP: /* Linux ATM defines this */
- off_linktype = 6;
- off_nl = 8;
+ off_nl_nosnap = 0; /* no 802.2 LLC */
return;
case DLT_LINUX_SLL: /* fake header for Linux cooked socket */
off_linktype = 14;
off_nl = 16;
+ off_nl_nosnap = 16; /* no 802.2 LLC */
return;
case DLT_LTALK:
*/
off_linktype = -1;
off_nl = 0;
+ off_nl_nosnap = 0; /* no 802.2 LLC */
return;
}
bpf_error("unknown data link type %d", linktype);
case Q_ISO:
b0 = gen_linktype(LLCSAP_ISONS);
- b1 = gen_cmp(off_nl + 3, BPF_B, (long)v);
+ b1 = gen_cmp(off_nl_nosnap, BPF_B, (long)v);
gen_and(b0, b1);
return b1;
if (orig_nl == (u_int)-1) {
orig_linktype = off_linktype; /* save original values */
orig_nl = off_nl;
+ orig_nl_nosnap = off_nl_nosnap;
switch (linktype) {
case DLT_EN10MB:
off_linktype = 16;
+ off_nl_nosnap = 18;
off_nl = 18;
break;
projects / libpcap / blobdiff