diff options
Diffstat (limited to 'gencode.c')
| -rw-r--r-- | gencode.c | 49 |
1 files changed, 48 insertions, 1 deletions
@@ -21,7 +21,7 @@ */ #ifndef lint static const char rcsid[] = - "@(#) $Header: /tcpdump/master/libpcap/gencode.c,v 1.122 2000-10-12 03:53:57 guy Exp $ (LBL)"; + "@(#) $Header: /tcpdump/master/libpcap/gencode.c,v 1.123 2000-10-22 04:15:55 guy Exp $ (LBL)"; #endif #ifdef HAVE_CONFIG_H @@ -2926,3 +2926,50 @@ gen_inbound(dir) dir); return (b0); } + +/* + * support IEEE 802.1Q VLAN trunk over ethernet + */ +struct block * +gen_vlan(vlan_num) + int vlan_num; +{ + static u_int orig_linktype = -1, orig_nl = -1; + struct block *b0; + + /* + * Change the offsets to point to the type and data fields within + * the VLAN packet. This is somewhat of a kludge. + */ + if (orig_nl == (u_int)-1) { + orig_linktype = off_linktype; /* save original values */ + orig_nl = off_nl; + + switch (linktype) { + + case DLT_EN10MB: + off_linktype = 16; + off_nl = 18; + break; + + default: + bpf_error("no VLAN support for data link type %d", + linktype); + /*NOTREACHED*/ + } + } + + /* check for VLAN */ + b0 = gen_cmp(orig_linktype, BPF_H, (bpf_int32)ETHERTYPE_8021Q); + + /* If a specific VLAN is requested, check VLAN id */ + if (vlan_num >= 0) { + struct block *b1; + + b1 = gen_cmp(orig_nl, BPF_H, (bpf_int32)vlan_num); + gen_and(b0, b1); + b0 = b1; + } + + return (b0); +} |