2012-09-20 17:46:42 +00:00
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/* packet-dtcp-ip.c
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* Routines for DTCP-IP dissection
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* (Digital Transmission Content Protection over IP)
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*
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* Copyright 2012, Martin Kaiser <martin@kaiser.cx>
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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 modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (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 along
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* with this program; if not, write to the Free Software Foundation, Inc.,
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* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
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*/
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/*
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* quote from www.dtcp.com:
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* "DTCP is a method of protecting audio and audiovisual entertainment
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* content on home and personal networks over highbandwidth bidirectional
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* digital interfaces"
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*
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* this dissector supports DTCP on top of TCP/IP
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* for now, only the AKE (authentication and key exchange)
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* messages are implemented
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*
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* the dissector is based on the publicly available (informative) specifications
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* obtained from http://www.dtcp.com/specifications.aspx
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* (complete specifications are available only to licensees)
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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/prefs.h>
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static int proto_dtcp_ip = -1;
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static guint pref_tcp_port = 0;
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2013-03-16 16:25:41 +00:00
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void proto_register_dtcp_ip(void);
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2012-09-20 17:46:42 +00:00
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void proto_reg_handoff_dtcp_ip(void);
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static gint ett_dtcp_ip = -1;
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static gint ett_dtcp_ip_ctrl = -1;
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static gint ett_dtcp_ip_ake_procedure = -1;
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static int hf_dtcp_ip_type = -1;
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static int hf_dtcp_ip_length = -1;
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static int hf_dtcp_ip_ctype = -1;
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static int hf_dtcp_ip_category = -1;
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static int hf_dtcp_ip_ake_id = -1;
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static int hf_dtcp_ip_subfct = -1;
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static int hf_dtcp_ip_ake_procedure = -1;
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static int hf_dtcp_ip_ake_proc_full = -1;
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static int hf_dtcp_ip_ake_proc_ex_full = -1;
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static int hf_dtcp_ip_ake_xchg_key = -1;
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static int hf_dtcp_ip_subfct_dep = -1;
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static int hf_dtcp_ip_ake_label = -1;
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static int hf_dtcp_ip_number = -1;
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static int hf_dtcp_ip_status = -1;
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static int hf_dtcp_ip_ake_info = -1;
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#define CTRL_LEN 8 /* control block is 8 bytes long */
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/* these definitions are taken from the public DTCP specification
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it sounds like the private version defines more subfunctions */
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static const value_string subfct[] = {
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{ 0x01, "challenge" },
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{ 0x02, "response" },
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{ 0x03, "exchange_key" },
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{ 0, NULL }
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};
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static const int *ake_procedure_fields[] = { /* must be int, not gint */
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&hf_dtcp_ip_ake_proc_full,
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&hf_dtcp_ip_ake_proc_ex_full,
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NULL
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};
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/* only one bit may be set in exchange_key, we can use a value string */
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static const value_string xchg_key[] = {
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{ 0x00, "None" },
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{ 0x08, "Exchange key (K_X) for AES-128" },
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{ 0x20, "Session Exchange key (K_S) for AES-128" },
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{ 0x40, "Remote Exchange key (K_R) for AES-128" },
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{ 0, NULL }
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};
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static const value_string ctrl_status[] = {
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{ 0x0, "No error" },
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{ 0x1, "Support for no more authentication procedures is currently available" },
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{ 0x7, "Any other error" },
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{ 0xF, "No information" },
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{ 0, NULL }
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};
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/* check if the packet is actually DTCP-IP */
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static gboolean
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dtcp_ip_check_packet(tvbuff_t *tvb)
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{
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guint offset = 0;
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guint8 type;
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guint16 length;
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/* a minimum DTCP-IP AKE packet has Type (1 byte),
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Length (2 bytes) and Control (8 bytes) */
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if (tvb_reported_length(tvb) < 1+2+CTRL_LEN)
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return FALSE;
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type = tvb_get_guint8(tvb, offset);
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/* all DTCP-IP AKE packets have type 1 */
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if (type != 1)
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return FALSE;
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offset++;
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/* length field is length of the control block +
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length of ake_info */
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length = tvb_get_ntohs(tvb, offset);
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if (length < CTRL_LEN)
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return FALSE;
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return TRUE;
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}
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static int
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dissect_dtcp_ip(tvbuff_t *tvb, packet_info *pinfo,
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proto_tree *tree, void *data _U_)
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{
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guint offset = 0;
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guint16 length;
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proto_item *pi, *pi_ctrl;
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proto_tree *dtcp_ip_tree = NULL, *dtcp_ip_ctrl_tree = NULL;
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guint8 subfct_val;
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const gchar *subfct_str;
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gint ake_info_len;
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if (!dtcp_ip_check_packet(tvb))
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return 0; /* not a DTCP-IP packet */
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col_set_str(pinfo->cinfo, COL_PROTOCOL, "DTCP-IP");
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col_clear(pinfo->cinfo, COL_INFO);
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pi = proto_tree_add_protocol_format(tree, proto_dtcp_ip,
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tvb, 0, -1, "DTCP-IP");
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dtcp_ip_tree = proto_item_add_subtree(pi, ett_dtcp_ip);
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proto_tree_add_item(dtcp_ip_tree, hf_dtcp_ip_type,
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tvb, offset, 1, ENC_BIG_ENDIAN);
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offset++;
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length = tvb_get_ntohs(tvb, 1);
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/* overall packet length is 1 byte for tag + 2 bytes for length field +
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the value encoded in the length field */
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proto_item_set_len(pi, 1+2+length);
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proto_tree_add_item(dtcp_ip_tree, hf_dtcp_ip_length,
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tvb, offset, 2, ENC_BIG_ENDIAN);
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offset += 2;
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pi_ctrl = proto_tree_add_text(dtcp_ip_tree,
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tvb, offset, CTRL_LEN, "Control");
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dtcp_ip_ctrl_tree = proto_item_add_subtree(pi_ctrl, ett_dtcp_ip_ctrl);
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/* for now, we don't display the 4 reserved bits */
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proto_tree_add_item(dtcp_ip_ctrl_tree, hf_dtcp_ip_ctype,
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tvb, offset, 1, ENC_BIG_ENDIAN);
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offset++;
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proto_tree_add_item(dtcp_ip_ctrl_tree, hf_dtcp_ip_category,
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tvb, offset, 1, ENC_BIG_ENDIAN);
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proto_tree_add_item(dtcp_ip_ctrl_tree, hf_dtcp_ip_ake_id,
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tvb, offset, 1, ENC_BIG_ENDIAN);
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offset++;
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subfct_val = tvb_get_guint8(tvb, offset);
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subfct_str = val_to_str_const(subfct_val, subfct, "unknown");
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col_append_sep_fstr(pinfo->cinfo, COL_INFO, NULL,
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"%s (0x%x)", subfct_str, subfct_val);
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proto_tree_add_item(dtcp_ip_ctrl_tree, hf_dtcp_ip_subfct,
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tvb, offset, 1, ENC_BIG_ENDIAN);
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offset++;
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proto_tree_add_bitmask(dtcp_ip_ctrl_tree, tvb, offset,
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hf_dtcp_ip_ake_procedure, ett_dtcp_ip_ake_procedure,
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ake_procedure_fields, ENC_BIG_ENDIAN);
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offset++;
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proto_tree_add_item(dtcp_ip_ctrl_tree, hf_dtcp_ip_ake_xchg_key,
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tvb, offset, 1, ENC_BIG_ENDIAN);
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offset++;
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proto_tree_add_item(dtcp_ip_ctrl_tree, hf_dtcp_ip_subfct_dep,
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tvb, offset, 1, ENC_BIG_ENDIAN);
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offset++;
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proto_tree_add_item(dtcp_ip_ctrl_tree, hf_dtcp_ip_ake_label,
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tvb, offset, 1, ENC_BIG_ENDIAN);
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offset++;
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proto_tree_add_item(dtcp_ip_ctrl_tree, hf_dtcp_ip_number,
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tvb, offset, 1, ENC_BIG_ENDIAN);
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proto_tree_add_item(dtcp_ip_ctrl_tree, hf_dtcp_ip_status,
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tvb, offset, 1, ENC_BIG_ENDIAN);
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offset++;
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ake_info_len = length-CTRL_LEN;
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if (ake_info_len > 0) {
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proto_tree_add_item(dtcp_ip_tree, hf_dtcp_ip_ake_info,
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tvb, offset, ake_info_len, ENC_NA);
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offset += (guint)ake_info_len;
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}
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return offset;
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}
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void
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proto_register_dtcp_ip(void)
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{
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static hf_register_info hf[] = {
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{ &hf_dtcp_ip_type,
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{ "Type", "dtcp-ip.type", FT_UINT8, BASE_HEX,
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NULL, 0, NULL, HFILL } },
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{ &hf_dtcp_ip_length,
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{ "Length", "dtcp-ip.length", FT_UINT16, BASE_DEC,
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NULL, 0, NULL, HFILL } },
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/* it seems that / is not allowed in a filter name ... */
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{ &hf_dtcp_ip_ctype,
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{ "ctype/response", "dtcp-ip.ctrl.ctype_response", FT_UINT8,
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BASE_HEX, NULL, 0x0F, NULL, HFILL } },
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{ &hf_dtcp_ip_category,
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{ "Category", "dtcp-ip.ctrl.category", FT_UINT8, BASE_HEX,
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NULL, 0xF0, NULL, HFILL } },
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{ &hf_dtcp_ip_ake_id,
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{ "AKE_ID", "dtcp-ip.ctrl.ake_id", FT_UINT8, BASE_HEX,
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NULL, 0x0F, NULL, HFILL } },
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{ &hf_dtcp_ip_subfct,
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{ "Subfunction", "dtcp-ip.ctrl.subfunction", FT_UINT8, BASE_HEX,
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VALS(subfct), 0, NULL, HFILL } },
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{ &hf_dtcp_ip_ake_procedure,
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{ "AKE_procedure", "dtcp-ip.ctrl.ake_procedure", FT_UINT8,
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BASE_HEX, NULL, 0, NULL, HFILL } },
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/* 8 is the bit witdh of the field */
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{ &hf_dtcp_ip_ake_proc_full,
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{ "Full Authentication procedure",
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"dtcp-ip.ctrl.ake_procedure.full_auth", FT_BOOLEAN, 8,
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NULL, 0x04, NULL, HFILL } },
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{ &hf_dtcp_ip_ake_proc_ex_full,
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{ "Extended Full Authentication procedure",
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"dtcp-ip.ctrl.ake_procedure.ex_full_auth", FT_BOOLEAN, 8,
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NULL, 0x08, NULL, HFILL } },
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{ &hf_dtcp_ip_ake_xchg_key,
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{ "exchange_key", "dtcp-ip.ctrl.exchange_key", FT_UINT8, BASE_HEX,
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VALS(xchg_key), 0, NULL, HFILL } },
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{ &hf_dtcp_ip_subfct_dep,
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{ "subfunction_dependent", "dtcp-ip.ctrl.subfunction_dependent",
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FT_UINT8, BASE_HEX, NULL, 0, NULL, HFILL } },
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{ &hf_dtcp_ip_ake_label,
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{ "AKE_label", "dtcp-ip.ctrl.ake_label", FT_UINT8, BASE_HEX,
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NULL, 0, NULL, HFILL } },
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{ &hf_dtcp_ip_number,
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{ "number", "dtcp-ip.ctrl.number", FT_UINT8, BASE_HEX,
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NULL, 0xF0, NULL, HFILL } },
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{ &hf_dtcp_ip_status,
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{ "Status", "dtcp-ip.ctrl.status", FT_UINT8, BASE_HEX,
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VALS(ctrl_status), 0x0F, NULL, HFILL } },
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{ &hf_dtcp_ip_ake_info,
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{ "AKE_Info", "dtcp-ip.ake_info", FT_BYTES, BASE_NONE,
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NULL, 0, NULL, HFILL } }
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};
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static gint *ett[] = {
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&ett_dtcp_ip,
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&ett_dtcp_ip_ctrl,
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&ett_dtcp_ip_ake_procedure
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};
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module_t *dtcp_ip_module;
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proto_dtcp_ip = proto_register_protocol(
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"Digital Transmission Content Protection over IP",
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"DTCP-IP", "dtcp-ip");
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proto_register_field_array(proto_dtcp_ip, hf, array_length(hf));
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proto_register_subtree_array(ett, array_length(ett));
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dtcp_ip_module = prefs_register_protocol(
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proto_dtcp_ip, proto_reg_handoff_dtcp_ip);
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prefs_register_uint_preference(dtcp_ip_module, "tcp.port",
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"TCP port", "TCP port number for DTCP-IP", 10, &pref_tcp_port);
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}
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void
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proto_reg_handoff_dtcp_ip(void)
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{
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static gboolean initialized = FALSE;
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static dissector_handle_t dtcp_ip_handle = NULL;
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static guint current_tcp_port = 0;
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if (!initialized) {
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dtcp_ip_handle =
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new_create_dissector_handle(dissect_dtcp_ip, proto_dtcp_ip);
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initialized = TRUE;
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}
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else
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dissector_delete_uint("tcp.port", current_tcp_port, dtcp_ip_handle);
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current_tcp_port = pref_tcp_port;
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dissector_add_uint("tcp.port", current_tcp_port, dtcp_ip_handle);
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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: 4
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* tab-width: 8
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* indent-tabs-mode: nil
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* End:
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*
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* vi: set shiftwidth=4 tabstop=8 expandtab:
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* :indentSize=4:tabSize=8:noTabs=true:
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*/
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