forked from osmocom/wireshark
![Dario Lombardo](/assets/img/avatar_default.png)
Change-Id: I92c94448e6641716d03158a5f332c8b53709423a Reviewed-on: https://code.wireshark.org/review/25756 Petri-Dish: Dario Lombardo <lomato@gmail.com> Reviewed-by: Anders Broman <a.broman58@gmail.com>
319 lines
9.3 KiB
C
319 lines
9.3 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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* 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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* SPDX-License-Identifier: GPL-2.0-or-later
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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 <epan/packet.h>
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#include <epan/expert.h>
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#include "packet-mpls.h"
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void proto_register_pw_fr(void);
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void proto_reg_handoff_pw_fr(void);
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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 int hf_cw_padding = -1;
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static expert_field ei_payload_size_invalid = EI_INIT;
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static expert_field ei_cw_bits03 = EI_INIT;
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static expert_field ei_cw_packet_size_too_small = EI_INIT;
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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 dissector_handle_t pw_fr_mpls_handle;
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static int
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dissect_pw_fr( tvbuff_t * tvb, packet_info * pinfo, proto_tree * tree, void* data _U_ )
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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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};
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int 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, &ei_cw_packet_size_too_small,
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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 1;
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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 tvb_captured_length(tvb);
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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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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_set_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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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(pinfo, item, &ei_cw_bits03);
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}
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proto_tree_add_item( subtree, hf_cw_fecn, tvb, 0, 1, ENC_BIG_ENDIAN );
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proto_tree_add_item( subtree, hf_cw_becn, tvb, 0, 1, ENC_BIG_ENDIAN );
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proto_tree_add_item( subtree, hf_cw_de, tvb, 0, 1, ENC_BIG_ENDIAN );
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proto_tree_add_item( subtree, hf_cw_cr, tvb, 0, 1, ENC_BIG_ENDIAN );
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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, &ei_payload_size_invalid,
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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, &ei_payload_size_invalid,
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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, &ei_payload_size_invalid,
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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_item(subtree, hf_cw_padding, tvb,
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encaps_size+payload_size, payload_padding, ENC_NA);
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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, &ei_payload_size_invalid,
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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_length(tvb, encaps_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 tvb_captured_length(tvb);
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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(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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{&hf_cw_padding,{"Padding" ,"pwfr.padding" ,FT_BYTES, BASE_NONE
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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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static ei_register_info ei[] = {
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{ &ei_cw_packet_size_too_small, { "pwfr.packet_size_too_small", PI_MALFORMED, PI_ERROR, "PW packet is smaller than PW encapsulation header", EXPFILL }},
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{ &ei_cw_bits03, { "pwfr.cw.bits03.not_zero", PI_MALFORMED, PI_ERROR, "Bits 0..3 of Control Word must be 0", EXPFILL }},
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{ &ei_payload_size_invalid, { "pwfr.payload.size_invalid", PI_MALFORMED, PI_ERROR, "Bad Length: greater than FR payload size", EXPFILL }},
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};
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expert_module_t* expert_pwfr;
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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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expert_pwfr = expert_register_protocol(proto_encaps);
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expert_register_field_array(expert_pwfr, ei, array_length(ei));
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pw_fr_mpls_handle = 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_add_for_decode_as("mpls.label", pw_fr_mpls_handle);
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fr_stripped_address_handle = find_dissector_add_dependency("fr_stripped_address", proto_encaps);
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}
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/*
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* Editor modelines - http://www.wireshark.org/tools/modelines.html
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*
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* Local variables:
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* c-basic-offset: 8
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* tab-width: 8
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* indent-tabs-mode: t
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* End:
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*
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* vi: set shiftwidth=8 tabstop=8 noexpandtab:
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* :indentSize=8:tabSize=8:noTabs=false:
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*/
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