![Bill Meier](/assets/img/avatar_default.png)
packet-mpls.c: - refactor dissect_pw_ach(); - create/uer value_string_ext as appropriate; - use call_dissector() rather than direct dissector call in one cse; all: - use 'LABEL' prefix for a set of rather generic enum identifiers; - fix some cases of calling expert...() or sub-dissectors under 'if(tree)'; - reformat some hf[] entries; - do some whitespace changes. svn path=/trunk/; revision=45195
299 lines
8.8 KiB
C
299 lines
8.8 KiB
C
/* packet-pw-fr.c
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* Routines for Frame Relay MPLS PW dissection as per RFC4619.
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* Copyright 2009, Dmitry Trebich, Artem Tamazov <artem.tamazov@tellabs.com>
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*
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* $Id$
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*
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* Wireshark - Network traffic analyzer
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* By Gerald Combs <gerald@wireshark.org>
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* Copyright 1998 Gerald Combs
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License
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* as published by the Free Software Foundation; either version 2
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* of the License, or (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
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*
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* History:
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* ---------------------------------
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* 18.03.2009 initial implementation
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* - FR DLCI mode
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* Not supported yet:
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* - Correct FR decode for encapsulations which contain fragmented FR frames.
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* - FR DLCI Martini (legacy) mode (i.e. legacy CW).
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*/
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#include "config.h"
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#include <glib.h>
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#include <epan/packet.h>
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#include <epan/expert.h>
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#include "packet-mpls.h"
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static gint proto_encaps = -1;
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static gint ett_encaps = -1;
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/*static int hf_pw_fr = -1;*/
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static int hf_cw_bits03 = -1;
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static int hf_cw_fecn = -1;
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static int hf_cw_becn = -1;
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static int hf_cw_de = -1;
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static int hf_cw_cr = -1;
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static int hf_cw_frg = -1;
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static int hf_cw_len = -1;
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static int hf_cw_seq = -1;
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static const value_string vals_frg[] = {
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{ 0x0, "Unfragmented" },
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{ 0x1, "First fragment" },
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{ 0x2, "Last fragment" },
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{ 0x3, "Intermediate fragment" },
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{ 0, NULL }
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};
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static dissector_handle_t fr_stripped_address_handle;
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static void
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dissect_pw_fr( tvbuff_t * tvb, packet_info * pinfo, proto_tree * tree )
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{
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gint packet_size;
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gint payload_size;
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gint payload_padding;
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const int encaps_size = 4; /*encapsulation consists of mandatory CW only*/
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enum {
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PQ_CW_BAD = 0x001
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,PQ_CW_BAD_BITS03 = 0x002
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,PQ_CW_BAD_LEN_GT_PACKET = 0x004
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,PQ_CW_BAD_LEN_MUST_BE_ZERO = 0x008
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,PQ_CW_BAD_LEN_MUST_BE_NONZERO = 0x010
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,PQ_PAYLOAD_SIZE_ZERO = 0x020
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} packet_quality;
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packet_size = tvb_reported_length_remaining(tvb, 0);
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if (packet_size < encaps_size)
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{
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{
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proto_item *item;
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item = proto_tree_add_item(tree, proto_encaps, tvb, 0, -1, ENC_NA);
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expert_add_info_format(pinfo, item, PI_MALFORMED, PI_ERROR,
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"PW packet (%d) is smaller than PW encapsulation header (%d)"
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,(int)packet_size,(int)encaps_size);
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}
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col_set_str(pinfo->cinfo, COL_PROTOCOL, "FR PW");
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col_set_str(pinfo->cinfo, COL_INFO, "Malformed: PW packet < PW encapsulation header");
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return;
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}
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if (dissect_try_cw_first_nibble(tvb,pinfo,tree))
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{
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return;
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}
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/* check how "good" is this packet */
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/* also decide payload length from packet size and CW */
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packet_quality = 0;
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if (0 != (tvb_get_guint8(tvb, 0) & 0xf0 /*bits03*/))
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{
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packet_quality |= PQ_CW_BAD + PQ_CW_BAD_BITS03;
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}
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{
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/* RFC4619:
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* [ If the frame's length (defined as the
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* length of the layer 2 payload plus the length of the control word)
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* is less than 64 octets, the length field MUST be set to the PW
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* payload length. Otherwise, the length field MUST be set to zero. ]
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*
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* Note difference from RFC4385 which states that:
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* [..the length field MUST be set to the length of the PW payload
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* *plus* the length of the *PWMCW*. ]
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*/
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int cw_len;
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gint payload_size_packet; /*derived from packet size*/
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cw_len = tvb_get_guint8(tvb, 1) & 0x3f;
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payload_size_packet = packet_size - encaps_size;
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/*
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* Initial assumptions.
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*/
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payload_size = payload_size_packet;
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payload_padding = 0;
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if (payload_size_packet < 64)
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{
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gint payload_size_cw; /*derived from cw*/
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payload_size_cw = cw_len; /*RFC4619-specific*/
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if (payload_size_cw == 0)
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{
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packet_quality |= PQ_CW_BAD + PQ_CW_BAD_LEN_MUST_BE_NONZERO;
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}
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else if (payload_size_cw > payload_size_packet)
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{
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packet_quality |= PQ_CW_BAD + PQ_CW_BAD_LEN_GT_PACKET;
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}
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else /* ok */
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{
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payload_size = payload_size_cw;
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payload_padding = payload_size_packet - payload_size_cw; /* >=0 */
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}
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}
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else /* payload_size_packet >= 64 */
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{
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if (cw_len != 0)
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{
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packet_quality |= PQ_CW_BAD + PQ_CW_BAD_LEN_MUST_BE_ZERO;
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}
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}
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}
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if (payload_size == 0)
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{
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packet_quality |= PQ_PAYLOAD_SIZE_ZERO;
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}
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col_set_str(pinfo->cinfo, COL_PROTOCOL, "FR PW");
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if (check_col(pinfo->cinfo, COL_INFO))
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{
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col_clear(pinfo->cinfo, COL_INFO);
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if (packet_quality & PQ_CW_BAD)
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{
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col_append_str(pinfo->cinfo, COL_INFO, "CW:Malformed, ");
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}
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col_append_fstr(pinfo->cinfo, COL_INFO, "%d payload octets", (int)payload_size);
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if (payload_padding != 0)
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{
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col_append_fstr(pinfo->cinfo, COL_INFO, ", %d padding", (int)payload_padding);
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}
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}
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{
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proto_tree* subtree;
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proto_item* item_headline;
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proto_item* item;
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item_headline = proto_tree_add_item(tree, proto_encaps, tvb, 0, 4, ENC_NA);
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proto_item_append_text(item_headline, ": 0x%.8" G_GINT32_MODIFIER "x", tvb_get_ntohl(tvb, 0));
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subtree = proto_item_add_subtree(item_headline, ett_encaps);
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if (packet_quality & PQ_CW_BAD_BITS03) /*display only if value is wrong*/
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{
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item = proto_tree_add_item(subtree, hf_cw_bits03, tvb, 0, 1, ENC_BIG_ENDIAN);
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expert_add_info_format(pinfo, item, PI_MALFORMED, PI_ERROR,
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"Bits 0..3 of Control Word must be 0");
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}
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(void)proto_tree_add_item( subtree, hf_cw_fecn, tvb, 0, 1, ENC_BIG_ENDIAN );
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(void)proto_tree_add_item( subtree, hf_cw_becn, tvb, 0, 1, ENC_BIG_ENDIAN );
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(void)proto_tree_add_item( subtree, hf_cw_de, tvb, 0, 1, ENC_BIG_ENDIAN );
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(void)proto_tree_add_item( subtree, hf_cw_cr, tvb, 0, 1, ENC_BIG_ENDIAN );
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(void)proto_tree_add_item( subtree, hf_cw_frg, tvb, 1, 1, ENC_BIG_ENDIAN );
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item = proto_tree_add_item( subtree, hf_cw_len, tvb, 1, 1, ENC_BIG_ENDIAN );
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if (packet_quality & PQ_CW_BAD_LEN_GT_PACKET)
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{
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expert_add_info_format(pinfo, item, PI_MALFORMED, PI_ERROR,
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"Bad Length: greater than FR payload size (%d)",
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(int)payload_size);
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}
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if (packet_quality & PQ_CW_BAD_LEN_MUST_BE_NONZERO)
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{
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expert_add_info_format(pinfo, item, PI_MALFORMED, PI_ERROR,
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"Bad Length: must be non-zero if FR PW packet size (%d) is < 64",
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(int)(payload_size+encaps_size));
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}
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if (packet_quality & PQ_CW_BAD_LEN_MUST_BE_ZERO)
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{
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expert_add_info_format(pinfo, item, PI_MALFORMED, PI_ERROR,
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"Bad Length: must be 0 if FR PW packet size (%d) is >= 64",
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(int)(payload_size+encaps_size));
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}
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proto_tree_add_item( subtree, hf_cw_seq, tvb, 2, 2, ENC_BIG_ENDIAN );
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if (payload_padding > 0)
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{
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proto_tree_add_text(subtree, tvb,
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encaps_size+payload_size, payload_padding,
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"[Padding: %d octets]",(int)payload_padding);
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}
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if (packet_quality & PQ_PAYLOAD_SIZE_ZERO)
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{
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expert_add_info_format(pinfo, item_headline, PI_MALFORMED, PI_WARN,
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"FR payload size must be non-zero");
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}
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}
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if (payload_size > 0)
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{
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tvbuff_t *tvb_payload;
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tvb_payload = tvb_new_subset(tvb, encaps_size, payload_size, payload_size);
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call_dissector( fr_stripped_address_handle, tvb_payload, pinfo, tree );
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}
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return;
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}
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void
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proto_register_pw_fr(void)
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{
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static hf_register_info hf[] = {
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{&hf_cw_bits03 ,{"Bits 0 to 3" ,"pwfr.bits03" ,FT_UINT8 ,BASE_HEX
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,NULL ,0xf0 ,NULL
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,HFILL }}
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,{&hf_cw_fecn ,{"FR FECN" ,"pwfr.fecn" ,FT_UINT8 ,BASE_DEC
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,NULL ,0x08 ,"FR Forward Explicit Congestion Notification bit"
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,HFILL}}
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,{&hf_cw_becn ,{"FR BECN" ,"pwfr.becn" ,FT_UINT8 ,BASE_DEC
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,NULL ,0x04 ,"FR Backward Explicit Congestion Notification bit"
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,HFILL}}
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,{&hf_cw_de ,{"FR DE bit" ,"pwfr.de" ,FT_UINT8 ,BASE_DEC
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,NULL ,0x02 ,"FR Discard Eligibility bit"
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,HFILL}}
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,{&hf_cw_cr ,{"FR Frame C/R" ,"pwfr.cr" ,FT_UINT8 ,BASE_DEC
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,NULL ,0x01 ,"FR frame Command/Response bit"
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,HFILL}}
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,{&hf_cw_frg ,{"Fragmentation" ,"pwfr.frag" ,FT_UINT8 ,BASE_DEC
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,vals_frg ,0xc0 ,NULL
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,HFILL}}
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,{&hf_cw_len ,{"Length" ,"pwfr.length" ,FT_UINT8 ,BASE_DEC
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,NULL ,0x3f ,NULL
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,HFILL}}
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,{&hf_cw_seq ,{"Sequence number" ,"pwfr.length" ,FT_UINT16 ,BASE_DEC
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,NULL ,0 ,NULL
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,HFILL}}
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};
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static gint *ett[] = {
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&ett_encaps
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};
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proto_encaps = proto_register_protocol( "PW Frame Relay DLCI Control Word",
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"Frame Relay DLCI PW",
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"pwfr");
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proto_register_field_array(proto_encaps, hf, array_length(hf));
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proto_register_subtree_array(ett, array_length(ett));
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register_dissector("pw_fr", dissect_pw_fr, proto_encaps );
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}
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void
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proto_reg_handoff_pw_fr(void)
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{
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dissector_handle_t h;
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h = find_dissector("pw_fr");
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dissector_add_uint("mpls.label", MPLS_LABEL_INVALID, h);
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fr_stripped_address_handle = find_dissector("fr_stripped_address");
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}
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