Get rid of some other uses of ethertype() for protocols that don't have

a trailer.

Clean up the NHRP dissector's handling of the protocol ID to fully
implement RFC 2332 (and mention that 2332 is the RFC for NHRP).  Don't
compute the checksum unless we have all the packet data, and don't use
the captured length as the actual packet length.  Check for an invalid
extension offset value.  Get rid of some unneeded
tvb_ensure_bytes_exist() calls.  Dissect - and set the columns -
regardless of whether we're building the protocol tree.  Mark the packet
in error reports as an error packet.


git-svn-id: http://anonsvn.wireshark.org/wireshark/trunk@28273 f5534014-38df-0310-8fa8-9805f1628bb7

1 files changed, 228 insertions, 82 deletions

diff --git a/epan/dissectors/packet-nhrp.c b/epan/dissectors/packet-nhrp.c
index bce5248374..2b223051da 100644
--- a/epan/dissectors/packet-nhrp.c
+++ b/epan/dissectors/packet-nhrp.c
@@ -1,5 +1,6 @@
 /* packet-nhrp.c
- * Routines for NBMA Next Hop Resoultion Protocol
+ * Routines for NBMA Next Hop Resolution Protocol
+ * RFC 2332 plus Cisco extensions (documented where?)
  *
  * $Id$
  *
@@ -21,11 +22,8 @@
  * along with this program; if not, write to the Free Software
  * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
  *
- *
- *
  * CIE decoding for extensions and Cisco 12.4T extensions
  * added by Timo Teras <timo.teras@iki.fi>
- *
  */
 
 #ifdef HAVE_CONFIG_H
@@ -39,12 +37,16 @@
 #include <glib.h>
 #include <epan/packet.h>
 #include <epan/addr_resolv.h>
+#include <epan/expert.h>
 #include <epan/etypes.h>
 #include <epan/ipproto.h>
 #include <epan/greproto.h>
+#include <epan/nlpid.h>
+#include <epan/oui.h>
 #include <epan/sminmpec.h>
 #include <epan/afn.h>
 #include <epan/in_cksum.h>
+#include <epan/dissectors/packet-llc.h>
 #include "packet-nhrp.h"
 
 /* forward reference */
@@ -55,7 +57,8 @@ void dissect_nhrp(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree);
 static int proto_nhrp = -1;
 static int hf_nhrp_hdr_afn = -1;
 static int hf_nhrp_hdr_pro_type = -1;
-static int hf_nhrp_hdr_pro_snap = -1;
+static int hf_nhrp_hdr_pro_snap_oui = -1;
+static int hf_nhrp_hdr_pro_snap_pid = -1;
 static int hf_nhrp_hdr_hopcnt = -1;
 static int hf_nhrp_hdr_pktsz = -1;
 static int hf_nhrp_hdr_chksum = -1;
@@ -220,6 +223,27 @@ static const value_string nhrp_cie_code_vals[] = {
 	{ 0, 								NULL }
 };
 
+static dissector_table_t osinl_subdissector_table;
+static dissector_table_t osinl_excl_subdissector_table;
+static dissector_table_t ethertype_subdissector_table;
+
+static dissector_handle_t data_handle;
+
+typedef struct _e_nhrp {
+	guint16	ar_afn;
+	guint16	ar_pro_type;
+	guint32 ar_pro_type_oui;
+	guint16 ar_pro_type_pid;
+	guint8	ar_hopCnt;
+	guint16	ar_pktsz;
+	guint16	ar_chksum;
+	guint16	ar_extoff;
+	guint8	ar_op_version;
+	guint8	ar_op_type;
+	guint8	ar_shtl;
+	guint8	ar_sstl;
+} e_nhrp_hdr;
+
 static guint16 nhrp_checksum(const guint8 *ptr, int len)
 {
 	vec_t cksum_vec[1];
@@ -230,15 +254,17 @@ static guint16 nhrp_checksum(const guint8 *ptr, int len)
 }
 
 void dissect_nhrp_hdr(tvbuff_t *tvb,
+					  packet_info *pinfo,
 					  proto_tree *tree,
 					  gint *pOffset,
 					  gint *pMandLen,
 					  gint *pExtLen,
+					  oui_info_t **pOuiInfo,
 					  e_nhrp_hdr *hdr)
 {
 	gint	offset = *pOffset;
-	gchar 	*pro_type_str = "";
-	gint 	total_len = tvb_length(tvb);
+	const gchar *pro_type_str;
+	guint   total_len = tvb_reported_length(tvb);
 	guint16	ipcsum, rx_chksum;
 	
 	proto_item *nhrp_tree_item = NULL;
@@ -247,6 +273,7 @@ void dissect_nhrp_hdr(tvbuff_t *tvb,
 	proto_tree *shtl_tree = NULL;
 	proto_item *sstl_tree_item = NULL;
 	proto_tree *sstl_tree = NULL;
+	proto_item *ti;
 
 	nhrp_tree_item = proto_tree_add_text(tree, tvb, offset, 20, "NHRP Fixed Header");
 	nhrp_tree = proto_item_add_subtree(nhrp_tree_item, ett_nhrp_hdr);
@@ -256,33 +283,62 @@ void dissect_nhrp_hdr(tvbuff_t *tvb,
 		total_len = hdr->ar_pktsz;
 	}
 
-    ipcsum = nhrp_checksum(tvb_get_ptr(tvb, offset, total_len), total_len);
-	
 	hdr->ar_afn = tvb_get_ntohs(tvb, offset);
 	proto_tree_add_item(nhrp_tree, hf_nhrp_hdr_afn, tvb, offset, 2, FALSE);
 	offset += 2;
 
 	hdr->ar_pro_type = tvb_get_ntohs(tvb, offset);
-	switch (hdr->ar_pro_type) {
-	case ETHERTYPE_IP:
-		pro_type_str = "IPv4";
-		break;
-	case ETHERTYPE_IPv6:
-		pro_type_str = "IPv6";
-		break;
-	default:
-		pro_type_str = "Unknown";
-		break;
+	if (hdr->ar_pro_type <= 0xFF) {
+		/* It's an NLPID */
+		pro_type_str = val_to_str(hdr->ar_pro_type, nlpid_vals,
+		    "Unknown NLPID");
+	} else if (hdr->ar_pro_type <= 0x3FF) {
+		/* Reserved for future use by the IETF */
+		pro_type_str = "Reserved for future use by the IETF";
+	} else if (hdr->ar_pro_type <= 0x04FF) {
+		/* Allocated for use by the ATM Forum */
+		pro_type_str = "Allocated for use by the ATM Forum";
+	} else if (hdr->ar_pro_type <= 0x05FF) {
+		/* Experimental/Local use */
+		pro_type_str = "Experimental/Local use";
+	} else {
+		pro_type_str = val_to_str(hdr->ar_pro_type, etype_vals,
+		    "Unknown Ethertype");
 	}
 	proto_tree_add_uint_format(nhrp_tree, hf_nhrp_hdr_pro_type, tvb, offset, 2,
-							   hdr->ar_pro_type,
-							   "Protocol Type (short form): %#x (%s)",
-							   hdr->ar_pro_type, pro_type_str);
+	    hdr->ar_pro_type, "Protocol Type (short form): %s (0x%04x)",
+	    pro_type_str, hdr->ar_pro_type);
 	offset += 2;
-	proto_tree_add_text(nhrp_tree, tvb, offset, 5,
+
+	if (hdr->ar_pro_type == NLPID_SNAP) {
+		/*
+		 * The long form protocol type is a SNAP OUI and PID.
+		 */
+		hdr->ar_pro_type_oui = tvb_get_ntoh24(tvb, offset);
+		proto_tree_add_uint(nhrp_tree, hf_nhrp_hdr_pro_snap_oui,
+		    tvb, offset, 3, hdr->ar_pro_type_oui);
+		offset += 3;
+
+		hdr->ar_pro_type_pid = tvb_get_ntohs(tvb, offset);
+		*pOuiInfo = get_snap_oui_info(hdr->ar_pro_type_oui);
+		if (*pOuiInfo != NULL) {
+			proto_tree_add_uint(nhrp_tree,
+			    *(*pOuiInfo)->field_info->p_id,
+			    tvb, offset, 2, hdr->ar_pro_type_pid);
+		} else {
+			proto_tree_add_uint(nhrp_tree, hf_nhrp_hdr_pro_snap_pid,
+			    tvb, offset, 2, hdr->ar_pro_type_pid);
+		}
+	} else {
+		/*
+		 * XXX - we should check that this is zero, as RFC 2332
+		 * says it should be zero.
+		 */
+		proto_tree_add_text(nhrp_tree, tvb, offset, 5,
 						"Protocol Type (long form): %s",
 						tvb_bytes_to_str(tvb, offset, 5));
-	offset += 5;
+		offset += 5;
+	}
 
 	proto_tree_add_item(nhrp_tree, hf_nhrp_hdr_hopcnt, tvb, offset, 1, FALSE);
 	offset += 1;
@@ -291,18 +347,29 @@ void dissect_nhrp_hdr(tvbuff_t *tvb,
 	offset += 2;
 
 	rx_chksum = tvb_get_ntohs(tvb, offset);
-	if (ipcsum == 0) {
-		proto_tree_add_uint_format(nhrp_tree, hf_nhrp_hdr_chksum, tvb, offset, 2, rx_chksum,
-								   "NHRP Packet checksum: 0x%04x [correct]", rx_chksum);
+	if (tvb_bytes_exist(tvb, 0, total_len)) {
+		ipcsum = nhrp_checksum(tvb_get_ptr(tvb, 0, total_len),
+		    total_len);
+		if (ipcsum == 0) {
+			proto_tree_add_uint_format(nhrp_tree, hf_nhrp_hdr_chksum, tvb, offset, 2, rx_chksum,
+			    "NHRP Packet checksum: 0x%04x [correct]", rx_chksum);
+		} else {
+			proto_tree_add_uint_format(nhrp_tree, hf_nhrp_hdr_chksum, tvb, offset, 2, rx_chksum,
+			    "NHRP Packet checksum: 0x%04x [incorrect, should be 0x%04x]", rx_chksum,
+			    in_cksum_shouldbe(rx_chksum, ipcsum));
+		}
 	} else {
 		proto_tree_add_uint_format(nhrp_tree, hf_nhrp_hdr_chksum, tvb, offset, 2, rx_chksum,
-								   "NHRP Packet checksum: 0x%04x [incorrect, should be 0x%04x]", rx_chksum,
-								   in_cksum_shouldbe(rx_chksum, ipcsum));
+		    "NHRP Packet checksum: 0x%04x [not all data available]", rx_chksum);
 	}
 	offset += 2;
 
 	hdr->ar_extoff = tvb_get_ntohs(tvb, offset);
-	proto_tree_add_item(nhrp_tree, hf_nhrp_hdr_extoff, tvb, offset, 2, FALSE);
+	ti = proto_tree_add_item(nhrp_tree, hf_nhrp_hdr_extoff, tvb, offset, 2, FALSE);
+	if (hdr->ar_extoff < 20) {
+		expert_add_info_format(pinfo, ti, PI_MALFORMED, PI_ERROR,
+		    "Extension offset is less than the fixed header length");
+	}
 	offset += 2;
 
 	hdr->ar_op_version = tvb_get_guint8(tvb, offset);
@@ -337,11 +404,22 @@ void dissect_nhrp_hdr(tvbuff_t *tvb,
 	
 	*pOffset = offset;
 	if (hdr->ar_extoff) {
-		*pMandLen = hdr->ar_extoff - 20;
-		*pExtLen = total_len - hdr->ar_extoff;
+		if (hdr->ar_extoff >= 20) {
+			*pMandLen = hdr->ar_extoff - 20;
+			*pExtLen = total_len - hdr->ar_extoff;
+		} else {
+			/* Error */
+			*pMandLen = 0;
+			*pExtLen = 0;
+		}
 	}
 	else {
-		*pMandLen = total_len - 20;
+		if (total_len >= 20)
+			*pMandLen = total_len - 20;
+		else {
+			/* "Can't happen" - we would have thrown an exception */
+			*pMandLen = 0;
+		}
 		*pExtLen = 0;
 	}
 }
@@ -360,10 +438,10 @@ void dissect_cie_list(tvbuff_t *tvb,
 	guint8 val;
 
 	while ((offset + 12) <= cieEnd) {
-		gint cli_addr_len = tvb_get_guint8(tvb, offset + 8);
-		gint cli_saddr_len = tvb_get_guint8(tvb, offset + 9);
-		gint cli_prot_len = tvb_get_guint8(tvb, offset + 10);
-		gint cie_len = 12 + cli_addr_len + cli_saddr_len + cli_prot_len;
+		guint cli_addr_len = tvb_get_guint8(tvb, offset + 8);
+		guint cli_saddr_len = tvb_get_guint8(tvb, offset + 9);
+		guint cli_prot_len = tvb_get_guint8(tvb, offset + 10);
+		guint cie_len = 12 + cli_addr_len + cli_saddr_len + cli_prot_len;
 		proto_item *cie_tree_item = proto_tree_add_text(tree, tvb, offset, cie_len, "Client Information Entry");
 		proto_tree *cie_tree = proto_item_add_subtree(cie_tree_item, ett_nhrp_cie);
 
@@ -418,7 +496,6 @@ void dissect_cie_list(tvbuff_t *tvb,
 		offset += 1;
 
 		if (cli_addr_len) {
-			tvb_ensure_bytes_exist(tvb, offset, cli_addr_len);
 			if (cli_addr_len == 4) {
 				addr = tvb_get_ipv4(tvb, offset);
 				proto_tree_add_ipv4(cie_tree, hf_nhrp_client_nbma_addr, tvb, offset, 4, addr);
@@ -432,14 +509,12 @@ void dissect_cie_list(tvbuff_t *tvb,
 		}
 		
 		if (cli_saddr_len) {
-			tvb_ensure_bytes_exist(tvb, offset, cli_saddr_len);
 			proto_tree_add_text(cie_tree, tvb, offset, cli_saddr_len,
 								"Client NBMA Sub Address: %s",
 								tvb_bytes_to_str(tvb, offset, cli_saddr_len));
 		}
 
 		if (cli_prot_len) {
-			tvb_ensure_bytes_exist(tvb, offset, cli_prot_len);
 			if (cli_prot_len == 4) {
 				addr = tvb_get_ipv4(tvb, offset);
 				proto_tree_add_ipv4(cie_tree, hf_nhrp_client_prot_addr, tvb, offset, 4, addr);
@@ -458,6 +533,7 @@ void dissect_nhrp_mand(tvbuff_t *tvb,
 					   packet_info *pinfo,
 					   proto_tree *tree,
 					   gint *pOffset,
+					   oui_info_t *oui_info,
 					   e_nhrp_hdr *hdr,
 					   gint mandLen)
 {
@@ -555,7 +631,6 @@ void dissect_nhrp_mand(tvbuff_t *tvb,
 	/* TBD : Check for hdr->afn */
 	shl = hdr->ar_shtl & NHRP_SHTL_LEN_MASK;
 	if (shl) {
-		tvb_ensure_bytes_exist(tvb, offset, shl);
 		if (shl == 4) {
 			addr = tvb_get_ipv4(tvb, offset);
 			proto_tree_add_ipv4(nhrp_tree, hf_nhrp_src_nbma_addr, tvb, offset, 4, addr);
@@ -593,7 +668,7 @@ void dissect_nhrp_mand(tvbuff_t *tvb,
 	if (dstLen) {
 		if (dstLen == 4) {
 			addr = tvb_get_ipv4(tvb, offset);
-    		proto_tree_add_ipv4(nhrp_tree, hf_nhrp_dst_prot_addr, tvb, offset, 4, addr);
+			proto_tree_add_ipv4(nhrp_tree, hf_nhrp_dst_prot_addr, tvb, offset, 4, addr);
 		}
 		else {
 			proto_tree_add_text(nhrp_tree, tvb, offset, dstLen,
@@ -604,19 +679,85 @@ void dissect_nhrp_mand(tvbuff_t *tvb,
 	}
 
 	if (isInd) {
+		gboolean save_in_error_pkt;
 		gint pkt_len = mandEnd - offset;
 		proto_item *ind_tree_item = proto_tree_add_text(tree, tvb, offset, pkt_len, "Packet Causing Indication");
 		proto_tree *ind_tree = proto_item_add_subtree(ind_tree_item, ett_nhrp_indication);
+		gboolean dissected;
+		tvbuff_t *sub_tvb;
 
+		save_in_error_pkt = pinfo->in_error_pkt;
+		pinfo->in_error_pkt = TRUE;
+		sub_tvb = tvb_new_subset(tvb, offset, -1, -1);
 		if (isErr) {
-			tvbuff_t *sub_tvb;
-
-			sub_tvb = tvb_new_subset(tvb, offset, -1, -1);
 			dissect_nhrp(sub_tvb, pinfo, ind_tree);
 		}
 		else {
-			ethertype(hdr->ar_pro_type, tvb, offset, pinfo, ind_tree, NULL, -1, -1, 0);
+			if (hdr->ar_pro_type <= 0xFF) {
+				/* It's an NLPID */
+				if (hdr->ar_pro_type == NLPID_SNAP) {
+					/*
+					 * Dissect based on the SNAP OUI
+					 * and PID.
+					 */
+					if (hdr->ar_pro_type_oui == 0x000000) {
+						/*
+						 * "Should not happen", as
+						 * the protocol type should
+						 * be the Ethertype, but....
+						 */
+						dissected = dissector_try_port(
+						    ethertype_subdissector_table,
+						    hdr->ar_pro_type_pid,
+						    sub_tvb, pinfo, ind_tree);
+					} else {
+						/*
+						 * If we have a dissector
+						 * table, use it, otherwise
+						 * just dissect as data.
+						 */
+						if (oui_info != NULL) {
+							dissected = dissector_try_port(
+							    oui_info->table,
+							    hdr->ar_pro_type_pid,
+							    sub_tvb, pinfo,
+							    ind_tree);
+						} else
+							dissected = FALSE;
+					}
+				} else {
+					/*
+					 * Dissect based on the NLPID.
+					 */
+					dissected = dissector_try_port(
+					    osinl_subdissector_table,
+					    hdr->ar_pro_type, sub_tvb, pinfo,
+					    ind_tree) ||
+					            dissector_try_port(
+					    osinl_excl_subdissector_table,
+					    hdr->ar_pro_type, sub_tvb, pinfo,
+					    ind_tree);
+				}
+			} else if (hdr->ar_pro_type <= 0x3FF) {
+				/* Reserved for future use by the IETF */
+				dissected = FALSE;
+			} else if (hdr->ar_pro_type <= 0x04FF) {
+				/* Allocated for use by the ATM Forum */
+				dissected = FALSE;
+			} else if (hdr->ar_pro_type <= 0x05FF) {
+				/* Experimental/Local use */
+				dissected = FALSE;
+			} else {
+				dissected = dissector_try_port(
+				    ethertype_subdissector_table,
+				    hdr->ar_pro_type, sub_tvb, pinfo, ind_tree);
+			}
+			if (!dissected) {
+				call_dissector(data_handle, sub_tvb, pinfo,
+				    ind_tree);
+			}
 		}
+		pinfo->in_error_pkt = save_in_error_pkt;
 		offset = mandEnd;
 	}
 
@@ -679,6 +820,14 @@ void dissect_nhrp_ext(tvbuff_t *tvb,
 
 void dissect_nhrp(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree)
 {
+	e_nhrp_hdr hdr;
+	gint mandLen = 0;
+	gint extLen = 0;
+	gint offset = 0;
+	proto_item *ti = NULL;
+	proto_tree *nhrp_tree = NULL;
+	oui_info_t *oui_info;
+		
 	if (check_col(pinfo->cinfo, COL_PROTOCOL)) {
 		col_set_str(pinfo->cinfo, COL_PROTOCOL, "NHRP");
 	}
@@ -686,43 +835,32 @@ void dissect_nhrp(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree)
 		col_clear(pinfo->cinfo, COL_INFO);
 	}
 	
-	if (tree) {
-		e_nhrp_hdr hdr;
-		gint mandLen = 0;
-		gint extLen = 0;
-		gint offset = 0;
-		proto_item *ti = NULL;
-		proto_tree *nhrp_tree = NULL;
-		
-		/* Fixed header is always 20 bytes. */
-		tvb_ensure_bytes_exist(tvb, offset, 20);
-		memset(&hdr, 0, sizeof(e_nhrp_hdr));
+	memset(&hdr, 0, sizeof(e_nhrp_hdr));
 	
-		hdr.ar_op_type = tvb_get_guint8(tvb, 17);
-		
-		if (check_col(pinfo->cinfo, COL_INFO)) {
-			col_add_str(pinfo->cinfo, COL_INFO,
-						 val_to_str(hdr.ar_op_type, nhrp_op_type_vals,
-									"0x%02X - unknown"));
-		}
-		col_set_writable(pinfo->cinfo, FALSE);
-
-		ti = proto_tree_add_protocol_format(tree, proto_nhrp, tvb, 0, -1,
-											"Next Hop Resolution Protocol (%s)",
-											val_to_str(hdr.ar_op_type,
-													   nhrp_op_type_vals,
-													   "0x%02X - unknown"));
-		nhrp_tree = proto_item_add_subtree(ti, ett_nhrp);
+	hdr.ar_op_type = tvb_get_guint8(tvb, 17);
+	
+	if (check_col(pinfo->cinfo, COL_INFO)) {
+		col_add_str(pinfo->cinfo, COL_INFO,
+		    val_to_str(hdr.ar_op_type, nhrp_op_type_vals,
+			       "0x%02X - unknown"));
+	}
+	col_set_writable(pinfo->cinfo, FALSE);
+
+	ti = proto_tree_add_protocol_format(tree, proto_nhrp, tvb, 0, -1,
+	    "Next Hop Resolution Protocol (%s)",
+	    val_to_str(hdr.ar_op_type, nhrp_op_type_vals, "0x%02X - unknown"));
+	nhrp_tree = proto_item_add_subtree(ti, ett_nhrp);
 		
-		dissect_nhrp_hdr(tvb, nhrp_tree, &offset, &mandLen, &extLen, &hdr);
-		if (mandLen) {
-			dissect_nhrp_mand(tvb, pinfo, nhrp_tree, &offset, &hdr, mandLen);
-		}
+	dissect_nhrp_hdr(tvb, pinfo, nhrp_tree, &offset, &mandLen, &extLen,
+	    &oui_info, &hdr);
+	if (mandLen) {
+		dissect_nhrp_mand(tvb, pinfo, nhrp_tree, &offset, oui_info,
+		    &hdr, mandLen);
+	}
 
-		if (extLen) {
-			dissect_nhrp_ext(tvb, nhrp_tree, &offset, extLen);
-		}
-	} /* End of if (tree) */
+	if (extLen) {
+		dissect_nhrp_ext(tvb, nhrp_tree, &offset, extLen);
+	}
 }
 
 void
@@ -734,8 +872,10 @@ proto_register_nhrp(void)
 		  { "Address Family Number", 		"nhrp.hdr.afn", 	FT_UINT16, BASE_HEX_DEC, VALS(afn_vals), 0x0, "", HFILL }},
 		{ &hf_nhrp_hdr_pro_type,
 		  { "Protocol Type (short form)",	"nhrp.hdr.pro.type",FT_UINT16, BASE_HEX_DEC, NULL, 0x0, "", HFILL }},
-		{ &hf_nhrp_hdr_pro_snap,
-		  { "Protocol Type (long form)",	"nhrp.hdr.pro.snap",FT_UINT_BYTES, BASE_HEX, NULL, 0x0, "", HFILL }},
+		{ &hf_nhrp_hdr_pro_snap_oui,
+		  { "Protocol Type (long form) - OUI",	"nhrp.hdr.pro.snap.oui",FT_UINT24, BASE_HEX, VALS(oui_vals), 0x0, "", HFILL }},
+		{ &hf_nhrp_hdr_pro_snap_pid,
+		  { "Protocol Type (long form) - PID",	"nhrp.hdr.pro.snap.pid",FT_UINT16, BASE_HEX, NULL, 0x0, "", HFILL }},
 		{ &hf_nhrp_hdr_hopcnt,
 		  { "Hop Count", 					"nhrp.hdr.hopcnt", 	FT_UINT8, BASE_DEC, NULL, 0x0, "", HFILL }},
 		{ &hf_nhrp_hdr_pktsz,
@@ -869,6 +1009,12 @@ proto_reg_handoff_nhrp(void)
 {
 	dissector_handle_t nhrp_handle;
 
+	data_handle = find_dissector("data");
+
+	osinl_subdissector_table = find_dissector_table("osinl");
+	osinl_excl_subdissector_table = find_dissector_table("osinl.excl");
+	ethertype_subdissector_table = find_dissector_table("ethertype");
+
 	nhrp_handle = create_dissector_handle(dissect_nhrp, proto_nhrp);
 	dissector_add("ip.proto", IP_PROTO_NARP, nhrp_handle);
 	dissector_add("gre.proto", GRE_NHRP, nhrp_handle);