Make "link[N:M]" refer to the 802.11 header for all 802.11 DLT_ values,

including those with fixed-length radio headers (it already refers to
the 802.11 header for radiotap).

Add a new "radio" keyword, to allow access to the radio header.  In
theory, something to allow testing for specific signal strengths, etc.
might be useful, but radiotap makes that difficult as the code can't
loop through the header looking for the signal strength field, the loop
has to be unrolled, and some of the other headers might not have
standardized the meaning of some of the fields, so we require the user
to construct such a filter themselves, for now.

4 files changed, 71 insertions, 6 deletions

diff --git a/gencode.c b/gencode.c
index 1125b18f..82748d89 100644
--- a/gencode.c
+++ b/gencode.c
@@ -21,7 +21,7 @@
  */
 #ifndef lint
 static const char rcsid[] _U_ =
-    "@(#) $Header: /tcpdump/master/libpcap/gencode.c,v 1.241 2005-05-01 19:32:38 guy Exp $ (LBL)";
+    "@(#) $Header: /tcpdump/master/libpcap/gencode.c,v 1.242 2005-05-02 21:13:08 guy Exp $ (LBL)";
 #endif
 
 #ifdef HAVE_CONFIG_H
@@ -135,6 +135,7 @@ static struct block *root;
  * is relative to.
  */
 enum e_offrel {
+	OR_PACKET,	/* relative to the beginning of the packet */
 	OR_LINK,	/* relative to the link-layer header */
 	OR_NET,		/* relative to the network-layer header */
 	OR_NET_NOSNAP,	/* relative to the network-layer header, with no SNAP header at the link layer */
@@ -666,6 +667,12 @@ gen_ncmp(offrel, offset, size, mask, jtype, reverse, v)
 static int reg_ll_size;
 
 /*
+ * This is the offset of the beginning of the link-layer header.
+ * It's usually 0, except for 802.11 with a fixed-length radio header.
+ */
+static u_int off_ll;
+
+/*
  * This is the offset of the beginning of the MAC-layer header.
  * It's usually 0, except for ATM LANE.
  */
@@ -763,6 +770,11 @@ init_linktype(p)
 	off_proto = -1;
 	off_payload = -1;
 
+	/*
+	 * Also assume it's not 802.11 with a fixed-length radio header.
+	 */
+	off_ll = 0;
+
 	orig_linktype = -1;
 	orig_nl = -1;
 
@@ -925,6 +937,7 @@ init_linktype(p)
 		 * XXX - same variable-length header problem; at least
 		 * the Prism header is fixed-length.
 		 */
+		off_ll = 144;
 		off_linktype = 144+24;
 		off_nl = 144+32;	/* Prism+802.11+802.2+SNAP */
 		off_nl_nosnap = 144+27;	/* Prism+802.11+802.2 */
@@ -945,6 +958,7 @@ init_linktype(p)
 		 * number at an offset of 4 from the beginning
 		 * of the radio header.
 		 */
+		off_ll = 64;
 		off_linktype = 64+24;
 		off_nl = 64+32;		/* Radio+802.11+802.2+SNAP */
 		off_nl_nosnap = 64+27;	/* Radio+802.11+802.2 */
@@ -1161,10 +1175,14 @@ gen_load_a(offrel, offset, size)
 
 	switch (offrel) {
 
-	case OR_LINK:
+	case OR_PACKET:
 		s = gen_load_llrel(offset, size);
 		break;
 
+	case OR_LINK:
+		s = gen_load_llrel(off_ll + offset, size);
+		break;
+
 	case OR_NET:
 		s = gen_load_llrel(off_nl + offset, size);
 		break;
@@ -3051,6 +3069,9 @@ gen_host(addr, mask, proto, dir)
 	case Q_NETBEUI:
 		bpf_error("'netbeui' modifier applied to host");
 
+	case Q_RADIO:
+		bpf_error("'radio' modifier applied to host");
+
 	default:
 		abort();
 	}
@@ -3157,6 +3178,9 @@ gen_host6(addr, mask, proto, dir)
 	case Q_NETBEUI:
 		bpf_error("'netbeui' modifier applied to host");
 
+	case Q_RADIO:
+		bpf_error("'radio' modifier applied to host");
+
 	default:
 		abort();
 	}
@@ -3464,6 +3488,9 @@ gen_proto_abbrev(proto)
 		b1 = gen_linktype(LLCSAP_NETBEUI);
 		break;
 
+	case Q_RADIO:
+		bpf_error("'radio' is not a valid protocol type");
+
 	default:
 		abort();
 	}
@@ -4448,6 +4475,9 @@ gen_proto(v, proto, dir)
 	case Q_NETBEUI:
 		bpf_error("'netbeui proto' is bogus");
 
+	case Q_RADIO:
+		bpf_error("'radio proto' is bogus");
+
 	default:
 		abort();
 		/* NOTREACHED */
@@ -5093,6 +5123,31 @@ gen_load(proto, index, size)
 	default:
 		bpf_error("unsupported index operation");
 
+	case Q_RADIO:
+		/*
+		 * The offset is relative to the beginning of the packet
+		 * data, if we have a radio header.  (If we don't, this
+		 * is an error.)
+		 */
+		if (linktype != DLT_IEEE802_11_RADIO_AVS &&
+		    linktype != DLT_IEEE802_11_RADIO &&
+		    linktype != DLT_PRISM_HEADER)
+			bpf_error("radio information not present in capture");
+
+		/*
+		 * Load into the X register the offset computed into the
+		 * register specifed by "index".
+		 */
+		s = xfer_to_x(index);
+
+		/*
+		 * Load the item at that offset.
+		 */
+		tmp = new_stmt(BPF_LD|BPF_IND|size);
+		sappend(s, tmp);
+		sappend(index->s, s);
+		break;
+
 	case Q_LINK:
 		/*
 		 * The offset is relative to the beginning of
@@ -5124,9 +5179,14 @@ gen_load(proto, index, size)
 			s = xfer_to_x(index);
 
 		/*
-		 * Load the item at the offset we've put in the X register.
+		 * Load the item at the sum of the offset we've put in the
+		 * X register and the offset of the start of the link
+		 * layer header (which is 0 if the radio header is
+		 * variable-length; that header length is what we put
+		 * into the X register and then added to the index).
 		 */
 		tmp = new_stmt(BPF_LD|BPF_IND|size);
+		tmp->s.k = off_ll;
 		sappend(s, tmp);
 		sappend(index->s, s);
 		break;
diff --git a/gencode.h b/gencode.h
index c18dea58..74cded59 100644
--- a/gencode.h
+++ b/gencode.h
@@ -18,7 +18,7 @@
  * WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED WARRANTIES OF
  * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
  *
- * @(#) $Header: /tcpdump/master/libpcap/gencode.h,v 1.63 2005-05-01 08:37:06 guy Exp $ (LBL)
+ * @(#) $Header: /tcpdump/master/libpcap/gencode.h,v 1.64 2005-05-02 21:13:08 guy Exp $ (LBL)
  */
 
 /*
@@ -124,6 +124,8 @@
 #define Q_ISIS_PSNP     38
 #define Q_ISIS_LSP      39
 
+#define Q_RADIO		40
+
 /* Directional qualifiers. */
 
 #define Q_SRC		1
diff --git a/grammar.y b/grammar.y
index 5fad9bd4..16ff3795 100644
--- a/grammar.y
+++ b/grammar.y
@@ -22,7 +22,7 @@
  */
 #ifndef lint
 static const char rcsid[] _U_ =
-    "@(#) $Header: /tcpdump/master/libpcap/grammar.y,v 1.88 2005-05-01 08:37:06 guy Exp $ (LBL)";
+    "@(#) $Header: /tcpdump/master/libpcap/grammar.y,v 1.89 2005-05-02 21:13:09 guy Exp $ (LBL)";
 #endif
 
 #ifdef HAVE_CONFIG_H
@@ -134,6 +134,7 @@ pcap_parse()
 %token	LANE LLC METAC BCC SC ILMIC OAMF4EC OAMF4SC
 %token	OAM OAMF4 CONNECTMSG METACONNECT
 %token	VPI VCI
+%token	RADIO
 
 %type	<s> ID
 %type	<e> EID
@@ -313,6 +314,7 @@ pname:	  LINK			{ $$ = Q_LINK; }
 	| STP			{ $$ = Q_STP; }
 	| IPX			{ $$ = Q_IPX; }
 	| NETBEUI		{ $$ = Q_NETBEUI; }
+	| RADIO			{ $$ = Q_RADIO; }
 	;
 other:	  pqual TK_BROADCAST	{ $$ = gen_broadcast($1); }
 	| pqual TK_MULTICAST	{ $$ = gen_multicast($1); }
diff --git a/scanner.l b/scanner.l
index 0c6fad50..c1f35f21 100644
--- a/scanner.l
+++ b/scanner.l
@@ -22,7 +22,7 @@
 
 #ifndef lint
 static const char rcsid[] _U_ =
-    "@(#) $Header: /tcpdump/master/libpcap/scanner.l,v 1.100 2005-04-19 04:25:01 guy Exp $ (LBL)";
+    "@(#) $Header: /tcpdump/master/libpcap/scanner.l,v 1.101 2005-05-02 21:13:09 guy Exp $ (LBL)";
 #endif
 
 #ifdef HAVE_CONFIG_H
@@ -183,6 +183,7 @@ igmp		return IGMP;
 igrp		return IGRP;
 pim		return PIM;
 vrrp		return VRRP;
+radio		return RADIO;
 
 ip6		{
 #ifdef INET6