add baseline support for MPLS protocol and per-label filtering

[libpcap] / gencode.c

diff --git a/gencode.c b/gencode.c
index 857760eca22fa63f04f8b0bd5d5bf20fba99f159..3dc15f23995eccb459cc548b74fe9db9140dd0fd 100644 (file)
--- a/gencode.c
+++ b/gencode.c
@@ -21,7 +21,7 @@
  */
 #ifndef lint
 static const char rcsid[] _U_ =
-    "@(#) $Header: /tcpdump/master/libpcap/gencode.c,v 1.204 2004-04-07 18:43:29 guy Exp $ (LBL)";
+    "@(#) $Header: /tcpdump/master/libpcap/gencode.c,v 1.205 2004-06-16 08:20:29 hannes Exp $ (LBL)";
 #endif
 
 #ifdef HAVE_CONFIG_H
@@ -97,7 +97,7 @@ static const char rcsid[] _U_ =
 static jmp_buf top_ctx;
 static pcap_t *bpf_pcap;
 
-/* Hack for updating VLAN offsets. */
+/* Hack for updating VLAN, MPLS offsets. */
 static u_int   orig_linktype = -1U, orig_nl = -1U, orig_nl_nosnap = -1U;
 
 /* XXX */
@@ -5279,6 +5279,74 @@ gen_vlan(vlan_num)
        return (b0);
 }
 
+/*
+ * support for MPLS
+ */
+struct block *
+gen_mpls(label_num)
+       int label_num;
+{
+       struct  block   *b0;
+
+       /*
+        * Change the offsets to point to the type and data fields within
+        * the MPLS packet.  This is somewhat of a kludge.
+        */
+       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;
+                        
+                        b0 = gen_cmp(orig_linktype, BPF_H, (bpf_int32)ETHERTYPE_MPLS);
+                       break;
+
+               case DLT_PPP:
+                       off_linktype = 6;
+                       off_nl_nosnap = 8;
+                       off_nl = 8;
+                        
+                        b0 = gen_cmp(orig_linktype, BPF_H, (bpf_int32)PPP_MPLS_UCAST);
+                       break;
+
+                case DLT_C_HDLC:
+                        off_linktype = 6;
+                       off_nl_nosnap = 8;
+                       off_nl = 8;
+                        
+                        b0 = gen_cmp(orig_linktype, BPF_H, (bpf_int32)ETHERTYPE_MPLS);
+                        break;
+
+                        /* FIXME add other DLT_s ...
+                         * for Frame-Relay/and ATM this may get messy due to SNAP headers
+                         * leave it for now */
+
+               default:
+                       bpf_error("no MPLS support for data link type %d",
+                                 linktype);
+                       /*NOTREACHED*/
+               }
+       }
+
+       /* If a specific MPLS label is requested, check it */
+       if (label_num >= 0) {
+               struct block *b1;
+
+                label_num = label_num << 12; /* label is shifted 12 bits on the wire */
+               b1 = gen_mcmp(orig_nl, BPF_H, (bpf_int32)label_num, 0xfffff000); /* only compare the first 20 bits */
+               gen_and(b0, b1);
+               b0 = b1;
+       }
+
+       return (b0);
+}
+
 struct block *
 gen_atmfield_code(atmfield, jvalue, jtype, reverse)
        int atmfield;