forked from osmocom/wireshark
Make the LDP dissectors new-style dissectors, so they can reject packets
if the version number isn't 1; the LDP port number appears to be popular for ONC RPC protocols, and this lets them be dissected as such, at least if they don't begin with a 2-byte big-endian 1. Do a standard TCP loop, which: handles LDP headers split across TCP segments; gives each LDP PDU in a TCP stream a tvbuff of its own, so we don't run past the end of the PDU; gives each LDP PDU its own tree. svn path=/trunk/; revision=5261
This commit is contained in:
Guy Harris
parent
db119f15d4
commit
f643982382
282
packet-ldp.c
282
packet-ldp.c
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@ -1,7 +1,7 @@
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/* packet-ldp.c
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* Routines for LDP (RFC 3036) packet disassembly
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*
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* $Id: packet-ldp.c,v 1.36 2002/04/25 06:34:41 guy Exp $
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* $Id: packet-ldp.c,v 1.37 2002/04/28 00:18:50 guy Exp $
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*
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* Copyright (c) November 2000 by Richard Sharpe <rsharpe@ns.aus.com>
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*
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@ -50,6 +50,8 @@
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#include "prefs.h"
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#include "afn.h"
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#include "packet-frame.h"
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#define TCP_PORT_LDP 646
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#define UDP_PORT_LDP 646
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@ -1818,15 +1820,14 @@ dissect_tlv(tvbuff_t *tvb, guint offset, proto_tree *tree, int rem)
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/* Dissect a Message and return the number of bytes consumed ... */
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static int
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dissect_msg(tvbuff_t *tvb, guint offset, packet_info *pinfo, proto_tree *tree, int rem)
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dissect_msg(tvbuff_t *tvb, guint offset, packet_info *pinfo, proto_tree *tree)
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{
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guint16 type, typebak;
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guint8 extra=0;
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int length, ao=0, co;
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int length, rem, ao=0, co;
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proto_tree *ti = NULL, *msg_tree = NULL;
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length=tvb_reported_length_remaining(tvb, offset);
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rem=MIN(rem, length);
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rem=tvb_reported_length_remaining(tvb, offset);
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if( rem < 8 ) {/*chk for minimum header = type + length + msg_id*/
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if( check_col(pinfo->cinfo, COL_INFO) )
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@ -1908,120 +1909,219 @@ dissect_msg(tvbuff_t *tvb, guint offset, packet_info *pinfo, proto_tree *tree, i
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return length+8+extra;
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}
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/* Dissect a PDU and return the number of bytes consumed ... */
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static int
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dissect_ldp_pdu(tvbuff_t *tvb, guint offset, packet_info *pinfo, proto_tree *tree, int rem, guint ix)
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/* Dissect a PDU */
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static void
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dissect_ldp_pdu(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree)
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{
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int length, ao=0, co;
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int offset = 0, co;
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int rem, length;
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proto_tree *ti=NULL, *pdu_tree = NULL;
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length=tvb_reported_length_remaining(tvb, offset);
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rem=MIN(rem, length);
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if( rem < 10 ){/*don't even have a PDU header*/
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/*XXX Need changes in desegment_tcp to handle multiple requests*/
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#if 0
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if( pinfo->can_desegment && (pinfo->ptype==PT_TCP) && ldp_desegment ){
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pinfo->desegment_offset=offset;
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pinfo->desegment_len=10-rem;
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}
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#else
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if(tree)
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proto_tree_add_text(tree, tvb, offset, rem,"Not enough bytes for PDU Hdr in TCP segment");
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#endif
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return rem;
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}
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if (check_col(pinfo->cinfo, COL_PROTOCOL))
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col_set_str(pinfo->cinfo, COL_PROTOCOL, "LDP");
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if( (length = tvb_get_ntohs(tvb, offset + 2)) < 6 ) {/*not enough*/
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if( check_col(pinfo->cinfo, COL_INFO) && ix )
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col_append_fstr(pinfo->cinfo, COL_INFO, "PDU %u: ", ix);
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if( check_col(pinfo->cinfo, COL_INFO) ){
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col_append_fstr(pinfo->cinfo, COL_INFO, "Bad PDU Length ");
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}
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if(tree)
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proto_tree_add_text(tree, tvb, offset, rem,
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"Error processing PDU Length: length is %d, should be >= 6",
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length);
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return rem;
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}
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rem -=4;
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if( length>rem ){
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if( pinfo->can_desegment && (pinfo->ptype==PT_TCP) && ldp_desegment ){/*ask for more*/
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pinfo->desegment_offset=offset;
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pinfo->desegment_len=length-rem;
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}else {
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if( check_col(pinfo->cinfo, COL_INFO) && ix )
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col_append_fstr(pinfo->cinfo, COL_INFO, "PDU %u: ", ix);
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if( check_col(pinfo->cinfo, COL_INFO) )
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col_append_fstr(pinfo->cinfo, COL_INFO, "Bad PDU Length ");
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if(tree)
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proto_tree_add_text(tree, tvb, offset, rem+4,
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"Error processing PDU Length: length is %d, should be <= %d",
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length, rem);
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}
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return rem+4;
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}
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if( check_col(pinfo->cinfo, COL_INFO) && ix )
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col_append_fstr(pinfo->cinfo, COL_INFO, "PDU %u: ", ix);
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if (check_col(pinfo->cinfo, COL_INFO))
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col_clear(pinfo->cinfo, COL_INFO);
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if( tree ){
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ti=proto_tree_add_protocol_format(tree, proto_ldp, tvb, offset,
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length+4, ix?"LDP PDU %u":"LDP PDU", ix);
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ti=proto_tree_add_item(tree, proto_ldp, tvb, 0, -1, FALSE);
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pdu_tree = proto_item_add_subtree(ti, ett_ldp);
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proto_tree_add_item(pdu_tree, hf_ldp_version, tvb, offset, 2, FALSE);
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}
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if(pdu_tree){
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proto_tree_add_item(pdu_tree, hf_ldp_version, tvb, offset, 2, FALSE);
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proto_tree_add_item(pdu_tree, hf_ldp_pdu_len, tvb, offset+2, 2, FALSE);
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length = tvb_get_ntohs(tvb, offset+2);
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if( tree )
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proto_tree_add_uint(pdu_tree, hf_ldp_pdu_len, tvb, offset+2, 2, length);
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length += 4; /* add the version and type sizes */
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rem = tvb_reported_length_remaining(tvb, offset);
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if (length < rem)
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tvb_set_reported_length(tvb, length);
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if( tree ){
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proto_tree_add_item(pdu_tree, hf_ldp_lsr, tvb, offset+4, 4, FALSE);
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proto_tree_add_item(pdu_tree, hf_ldp_ls_id, tvb, offset+8, 2, FALSE);
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}
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offset += 10;
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length -= 6;
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while( (length-ao) > 0 ) {
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co=dissect_msg(tvb, offset, pinfo, pdu_tree, length-ao);
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while( tvb_reported_length_remaining(tvb, offset) > 0 ) {
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co=dissect_msg(tvb, offset, pinfo, pdu_tree);
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offset += co;
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ao += co;
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}
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return length+10;
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}
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static void
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static int
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dissect_ldp(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree)
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{
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if (check_col(pinfo->cinfo, COL_PROTOCOL))
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col_set_str(pinfo->cinfo, COL_PROTOCOL, "LDP");
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/*
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* Make sure the first PDU has a version number of 1;
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* if not, reject this, so we don't get confused by
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* packets that happen to be going to or from the
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* LDP port but that aren't LDP packets.
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*/
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if (!tvb_bytes_exist(tvb, 0, 2)) {
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/*
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* Not enough information to tell.
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*/
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return 0;
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}
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if (tvb_get_ntohs(tvb, 0) != 1) {
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/*
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* Not version 1.
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*/
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return 0;
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}
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if (check_col(pinfo->cinfo, COL_INFO))
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col_clear(pinfo->cinfo, COL_INFO);
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dissect_ldp_pdu(tvb, pinfo, tree);
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dissect_ldp_pdu(tvb, 0, pinfo, tree, tvb_reported_length(tvb), 0);
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/*
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* XXX - return minimum of this and the length of the PDU?
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*/
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return tvb_length(tvb);
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}
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static void
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static int
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dissect_ldp_tcp(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree)
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{
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int offset=0, length, rtn;
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guint ix=1;
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volatile gboolean first = TRUE;
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volatile int offset = 0;
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int length_remaining;
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guint16 plen;
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int length;
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tvbuff_t *next_tvb;
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while (tvb_reported_length_remaining(tvb, offset) != 0) {
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length_remaining = tvb_length_remaining(tvb, offset);
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if (check_col(pinfo->cinfo, COL_PROTOCOL))
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col_set_str(pinfo->cinfo, COL_PROTOCOL, "LDP");
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/*
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* Make sure the first PDU has a version number of 1;
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* if not, reject this, so we don't get confused by
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* packets that happen to be going to or from the
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* LDP port but that aren't LDP packets.
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*
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* XXX - this means we can't handle an LDP PDU of which
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* only one byte appears in a TCP segment. If that's
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* a problem, we'll either have to completely punt on
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* rejecting non-LDP packets, or will have to assume
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* that if we have only one byte, it's an LDP packet.
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*/
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if (first) {
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if (length_remaining < 2) {
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/*
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* Not enough information to tell.
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*/
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return 0;
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}
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if (tvb_get_ntohs(tvb, offset) != 1) {
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/*
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* Not version 1.
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*/
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return 0;
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}
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first = FALSE;
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}
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if (check_col(pinfo->cinfo, COL_INFO))
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col_clear(pinfo->cinfo, COL_INFO);
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/*
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* Can we do reassembly?
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*/
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if (ldp_desegment && pinfo->can_desegment) {
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/*
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* Yes - is the LDP header split across segment
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* boundaries?
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*/
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if (length_remaining < 4) {
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/*
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* Yes. Tell the TCP dissector where
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* the data for this message starts in
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* the data it handed us, and how many
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* more bytes we need, and return.
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*/
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pinfo->desegment_offset = offset;
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pinfo->desegment_len = 4 - length_remaining;
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return -pinfo->desegment_len;
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}
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}
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length=tvb_reported_length(tvb);
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while (length > 0){
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rtn = dissect_ldp_pdu(tvb, offset, pinfo, tree, length, ix++);
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offset += rtn;
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length -= rtn;
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/*
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* Get the length of the rest of the LDP packet.
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* XXX - check for a version of 1 first?
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*/
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plen = tvb_get_ntohs(tvb, offset + 2);
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/*
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* Can we do reassembly?
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*/
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if (ldp_desegment && pinfo->can_desegment) {
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/*
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* Yes - is the LDP packet split across segment
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* boundaries?
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*/
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if (length_remaining < plen + 4) {
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/*
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* Yes. Tell the TCP dissector where the
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* data for this message starts in the data
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* it handed us, and how many more bytes we
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* need, and return.
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*/
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pinfo->desegment_offset = offset;
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pinfo->desegment_len =
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(plen + 4) - length_remaining;
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return -pinfo->desegment_len;
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}
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}
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/*
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* Construct a tvbuff containing the amount of the payload
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* we have available. Make its reported length the
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* amount of data in the DNS-over-TCP packet.
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*
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* XXX - if reassembly isn't enabled. the subdissector
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* will throw a BoundsError exception, rather than a
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* ReportedBoundsError exception. We really want
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* a tvbuff where the length is "length", the reported
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* length is "plen + 4", and the "if the snapshot length
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* were infinite" length is the minimum of the
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* reported length of the tvbuff handed to us and "plen+4",
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* with a new type of exception thrown if the offset is
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* within the reported length but beyond that third length,
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* with that exception getting the "Unreassembled Packet"
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* error.
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*/
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length = length_remaining;
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if (length > plen + 4)
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length = plen + 4;
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next_tvb = tvb_new_subset(tvb, offset, length, plen + 4);
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/*
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* Dissect the LDP packet.
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*
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* Catch the ReportedBoundsError exception; if this
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* particular message happens to get a ReportedBoundsError
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* exception, that doesn't mean that we should stop
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* dissecting LDP messages within this frame or chunk of
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* reassembled data.
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*
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* If it gets a BoundsError, we can stop, as there's nothing
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* more to see, so we just re-throw it.
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*/
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TRY {
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dissect_ldp_pdu(next_tvb, pinfo, tree);
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}
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CATCH(BoundsError) {
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RETHROW;
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}
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CATCH(ReportedBoundsError) {
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show_reported_bounds_error(tvb, pinfo, tree);
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}
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ENDTRY;
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/*
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* Skip the LDP header and the payload.
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*/
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offset += plen + 4;
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}
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return tvb_length(tvb);
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}
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/* Register all the bits needed with the filtering engine */
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@ -2421,13 +2521,13 @@ proto_register_ldp(void)
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void
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proto_reg_handoff_ldp(void)
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{
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static int ldp_prefs_initialized = FALSE;
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static gboolean ldp_prefs_initialized = FALSE;
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static dissector_handle_t ldp_tcp_handle, ldp_handle;
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if (!ldp_prefs_initialized) {
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ldp_tcp_handle = create_dissector_handle(dissect_ldp_tcp, proto_ldp);
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ldp_handle = create_dissector_handle(dissect_ldp, proto_ldp);
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ldp_tcp_handle = new_create_dissector_handle(dissect_ldp_tcp, proto_ldp);
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ldp_handle = new_create_dissector_handle(dissect_ldp, proto_ldp);
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ldp_prefs_initialized = TRUE;
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