/* packet-zrtp.c
 * Routines for zrtp packet dissection
 * IETF draft draft-zimmermann-avt-zrtp-17
 * Copyright 2007, Sagar Pai <sagar@gmail.com>
 *
 * $Id: packet-zrtp.c 31672 2010-01-25 23:46:42Z gerald $
 *
 * Wireshark - Network traffic analyzer
 * By Gerald Combs <gerald@wireshark.org>
 * Copyright 1998 Gerald Combs
 *
 * Copied from packet-pop.c
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version 2
 * of the License, or (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
 */

#ifdef HAVE_CONFIG_H
# include "config.h"
#endif

#include <stdio.h>

#include <string.h>
#include <glib.h>
#include <epan/packet.h>
#include <epan/strutil.h>
#include <epan/crc32.h>

/*
  RTP header
*/
static int proto_zrtp = -1;
static int hf_zrtp_rtpversion = -1;
static int hf_zrtp_rtppadding = -1;
static int hf_zrtp_rtpextension = -1;
static int hf_zrtp_id = -1;
static int hf_zrtp_sequence = -1;
static int hf_zrtp_cookie = -1;
static int hf_zrtp_source_id = -1;

/*
  ZRTP header
*/
static int hf_zrtp_signature = -1;
static int hf_zrtp_msg_length = -1;
static int hf_zrtp_msg_type = -1;
static int hf_zrtp_msg_version = -1;

/*
  Hello Data
*/
static int hf_zrtp_msg_client_id = -1;
static int hf_zrtp_msg_zid = -1;
static int hf_zrtp_msg_mitm = -1;
static int hf_zrtp_msg_passive = -1;
static int hf_zrtp_msg_hash_count = -1;
static int hf_zrtp_msg_cipher_count = -1;
static int hf_zrtp_msg_authtag_count = -1;
static int hf_zrtp_msg_key_count = -1;
static int hf_zrtp_msg_sas_count = -1;
static int hf_zrtp_msg_hash = -1;
static int hf_zrtp_msg_cipher = -1;
static int hf_zrtp_msg_at = -1;
static int hf_zrtp_msg_keya = -1;
static int hf_zrtp_msg_sas = -1;
static int hf_zrtp_msg_hash_image = -1;

/*
  Commit Data
*/
static int hf_zrtp_msg_hvi = -1;
static int hf_zrtp_msg_nonce = -1;
static int hf_zrtp_msg_key_id = -1;

/*
  DHParts Data
*/
static int hf_zrtp_msg_rs1ID = -1;
static int hf_zrtp_msg_rs2ID = -1;
static int hf_zrtp_msg_auxs = -1;
static int hf_zrtp_msg_pbxs = -1;

/*
  Confirm Data
*/
static int hf_zrtp_msg_hmac = -1;
static int hf_zrtp_msg_cfb = -1;

/*
  Error Data
*/
static int hf_zrtp_msg_error = -1;

/*
  Ping Data
*/
static int hf_zrtp_msg_ping_version = -1;
static int hf_zrtp_msg_ping_endpointhash = -1;
static int hf_zrtp_msg_pingack_endpointhash = -1;
static int hf_zrtp_msg_ping_ssrc = -1;

/*
  Checksum Data
*/
static int hf_zrtp_checksum = -1;
static int hf_zrtp_checksum_good = -1;
static int hf_zrtp_checksum_bad = -1;

/*
  Sub-Tree
*/
static gint ett_zrtp = -1;
static gint ett_zrtp_msg = -1;
static gint ett_zrtp_msg_data = -1;

static gint ett_zrtp_msg_encrypted = -1;
static gint ett_zrtp_msg_pvr = -1;
static gint ett_zrtp_msg_hc = -1;
static gint ett_zrtp_msg_kc = -1;
static gint ett_zrtp_msg_ac = -1;
static gint ett_zrtp_msg_cc = -1;
static gint ett_zrtp_msg_sc = -1;

static gint ett_zrtp_checksum = -1;

/*
  Definitions
*/
#define ZRTP_ERR_10 0x10
#define ZRTP_ERR_20 0x20
#define ZRTP_ERR_30 0x30
#define ZRTP_ERR_40 0x40
#define ZRTP_ERR_51 0x51
#define ZRTP_ERR_52 0x52
#define ZRTP_ERR_53 0x53
#define ZRTP_ERR_54 0x54
#define ZRTP_ERR_55 0x55
#define ZRTP_ERR_56 0x56
#define ZRTP_ERR_61 0x61
#define ZRTP_ERR_62 0x62
#define ZRTP_ERR_63 0x63
#define ZRTP_ERR_70 0x70
#define ZRTP_ERR_80 0x80
#define ZRTP_ERR_90 0x90
#define ZRTP_ERR_A0 0xA0
#define ZRTP_ERR_100 0x100

/*
  Text for Display
*/
typedef struct _value_zrtp_versions {
  const gchar *version;
} value_zrtp_versions;


typedef struct _value_string_keyval {
  const gchar *key;
  const gchar *val;
} value_string_keyval;


const value_zrtp_versions valid_zrtp_versions[]=
  {
    {"1.1x"},
    {"1.0x"},
    {"0.95"},
    {"0.90"},
    {"0.85"},
    {NULL}
  };

const value_string_keyval zrtp_hash_type_vals[] =
  {
    { "S256",	"SHA-256 Hash"},
    { NULL,		NULL }
  };

const value_string_keyval zrtp_cipher_type_vals[] =
  {
    { "AES1",	"AES-CM with 128 bit keys"},
    { "AES2",	"AES-CM with 192 bit keys"},
    { "AES3",	"AES-CM with 256 bit keys"},
    { "2FS1",   "TwoFish with 128 bit keys"},
    { "2FS2",   "TwoFish with 192 bit keys"},
    { "2FS3",   "TwoFish with 256 bit keys"},
    { "CAM1",   "Camellia with 128 bit keys"},
    { "CAM2",   "Camellia with 192 bit keys"},
    { "CAM3",   "Camellia with 256 bit keys"},
    { NULL,		NULL }
  };

const value_string_keyval zrtp_auth_tag_vals[] =
  {
    { "HS32",	"HMAC-SHA1 32 bit authentication tag"},
    { "HS80",	"HMAC-SHA1 80 bit authentication tag"},
    { "SK32",	"Skein-512-MAC 32 bit authentication tag"},
    { "SK64",	"Skein-512-MAC 64 bit authentication tag"},
    { NULL,		NULL }
  };

const value_string_keyval zrtp_sas_type_vals[] =
  {
    { "B32 ",	"Short authentication string using base 32"},
    { "B256",	"Short authentication string using base 256"},
    { NULL,		NULL }
  };

const value_string_keyval zrtp_key_agreement_vals[] =
  {
    { "DH2k",	"DH mode with p=2048 bit prime"},
    { "DH3k",	"DH mode with p=3072 bit prime"},
    { "DH4k",	"DH mode with p=4096 bit prime"},
    { "Prsh",	"Preshared non-DH mode using shared secret"},
    { "EC25",	"Elliptic Curve DH-256"},
    { "EC38",	"Elliptic Curve DH-384"},
    { "EC52",	"Elliptic Curve DH-521"},
    { "Mult",	"Multistream mode"},
    { NULL,		NULL }
  };

const value_string zrtp_error_vals[] =
  {
    { ZRTP_ERR_10, "Malformed Packet (CRC OK but wrong structure)"},
    { ZRTP_ERR_20, "Critical Software Error"},
    { ZRTP_ERR_30, "Unsupported ZRTP version"},
    { ZRTP_ERR_40, "Hello Components mismatch"},
    { ZRTP_ERR_51, "Hash type unsupported"},
    { ZRTP_ERR_52, "Cipher type not supported"},
    { ZRTP_ERR_53, "Public key exchange not supported"},
    { ZRTP_ERR_54, "SRTP auth. tag not supported"},
    { ZRTP_ERR_55, "SAS scheme not supported"},
    { ZRTP_ERR_56, "No shared secret available, DH mode required"},
    { ZRTP_ERR_61, "DH Error: bad pv for initiator/responder value is (1,0,p-1)"},
    { ZRTP_ERR_62, "DH Error: bad hash commitment (hvi != hashed data)"},
    { ZRTP_ERR_63, "Received relayed SAS from untrusted MiTM"},
    { ZRTP_ERR_70, "Auth. Error Bad Confirm Packet HMAC"},
    { ZRTP_ERR_80, "Nonce is reused"},
    { ZRTP_ERR_90, "Equal ZID's in Hello"},
    { ZRTP_ERR_A0, "Service unavailable"},
    { ZRTP_ERR_100, "GoClear packet received, but not allowed"},
    { 0, NULL}
  };

static void
dissect_Hello(tvbuff_t *tvb, packet_info *pinfo, proto_tree *zrtp_tree);
static void
dissect_ErrorACK(packet_info *pinfo);
static void
dissect_Commit(tvbuff_t *tvb, packet_info *pinfo, proto_tree *zrtp_tree);
static void
dissect_ClearACK( packet_info *pinfo);
static void
dissect_Conf2ACK(packet_info *pinfo);
static void
dissect_HelloACK( packet_info *pinfo);
static void
dissect_GoClear(tvbuff_t *tvb,packet_info *pinfo, proto_tree *zrtp_tree);
static void
dissect_Error(tvbuff_t *tvb, packet_info *pinfo, proto_tree *zrtp_tree);
static void
dissect_Confirm(tvbuff_t *tvb, packet_info *pinfo, proto_tree *zrtp_tree,int part);
static void
dissect_DHPart(tvbuff_t *tvb, packet_info *pinfo, proto_tree *zrtp_tree,int part);
static void
dissect_SASrelay(tvbuff_t *tvb, packet_info *pinfo, proto_tree *zrtp_tree);
static void
dissect_RelayACK(packet_info *pinfo);
static void
dissect_Ping(tvbuff_t *tvb, packet_info *pinfo, proto_tree *zrtp_tree);
static void
dissect_PingACK(tvbuff_t *tvb, packet_info *pinfo, proto_tree *zrtp_tree);


static const gchar *
key_to_val(const gchar *key, int keylen, const value_string_keyval *kv, const gchar *fmt){
  int i=0;
  while (kv[i].key) {
    if (!strncmp(kv[i].key, key, keylen)){
      return(kv[i].val);
    }
    i++;
  }
  return ep_strdup_printf(fmt, key);
}

static const gchar *
check_valid_version(const gchar *version){
  int i=0;
  int match_size = (version[0] == '0') ? 4 : 3;
  while (valid_zrtp_versions[i].version) {
    if (!strncmp(valid_zrtp_versions[i].version, version, match_size)){
      return(valid_zrtp_versions[i].version);
    }
    i++;
  }
  return NULL;
}


static void
dissect_zrtp(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree)
{
  proto_tree   *zrtp_tree;
  proto_tree   *zrtp_msg_tree;
  proto_tree   *zrtp_msg_data_tree;
  proto_tree   *checksum_tree;
  proto_item   *ti;
  int          linelen;
  int          checksum_offset;
  unsigned char message_type[9];
  unsigned int prime_offset = 0;
  unsigned int msg_offset = 12;
  guint32      sent_crc, calc_crc;

  if (check_col(pinfo->cinfo, COL_PROTOCOL))
    col_set_str(pinfo->cinfo, COL_PROTOCOL, "ZRTP");

  if (check_col(pinfo->cinfo, COL_INFO))
    col_add_fstr(pinfo->cinfo, COL_INFO, "Unknown ZRTP Packet");

  ti = proto_tree_add_protocol_format(tree,proto_zrtp,tvb,0,-1,"ZRTP protocol");
  zrtp_tree = proto_item_add_subtree(ti,ett_zrtp);

  proto_tree_add_item(zrtp_tree,hf_zrtp_rtpversion,tvb,prime_offset+0,1,FALSE);
  proto_tree_add_item(zrtp_tree,hf_zrtp_rtppadding,tvb,prime_offset+0,1,FALSE);
  proto_tree_add_item(zrtp_tree,hf_zrtp_rtpextension,tvb,prime_offset+0,1,FALSE);

  proto_tree_add_item(zrtp_tree,hf_zrtp_sequence,tvb,prime_offset+2,2,FALSE);

  proto_tree_add_item(zrtp_tree,hf_zrtp_cookie,tvb,prime_offset+4,4,FALSE);

  proto_tree_add_item(zrtp_tree,hf_zrtp_source_id,tvb,prime_offset+8,4,FALSE);

  linelen = tvb_reported_length_remaining(tvb,msg_offset);
  checksum_offset = linelen-4;

  ti = proto_tree_add_protocol_format(zrtp_tree,proto_zrtp,tvb,msg_offset,linelen-4,"Message");
  zrtp_msg_tree = proto_item_add_subtree(ti,ett_zrtp_msg);

  proto_tree_add_item(zrtp_msg_tree,hf_zrtp_signature,tvb,msg_offset+0,2,FALSE);

  proto_tree_add_item(zrtp_msg_tree,hf_zrtp_msg_length,tvb,msg_offset+2,2,FALSE);

  tvb_memcpy(tvb,(void *)message_type,msg_offset+4,8);
  message_type[8] = '\0';
  proto_tree_add_item(zrtp_msg_tree,hf_zrtp_msg_type,tvb,msg_offset+4,8,FALSE);

  linelen = tvb_reported_length_remaining(tvb,msg_offset+12);

  if (!strncmp(message_type,"Hello   ",8)){
    ti = proto_tree_add_protocol_format(zrtp_msg_tree,proto_zrtp,tvb,msg_offset+12,linelen-4,"Data");
    zrtp_msg_data_tree = proto_item_add_subtree(ti,ett_zrtp_msg_data);
    dissect_Hello(tvb,pinfo,zrtp_msg_data_tree);
  } else if (!strncmp(message_type,"HelloACK",8)){
    dissect_HelloACK(pinfo);
  } else if (!strncmp(message_type,"Commit  ",8)){
    ti = proto_tree_add_protocol_format(zrtp_msg_tree,proto_zrtp,tvb,msg_offset+12,linelen-4,"Data");
    zrtp_msg_data_tree = proto_item_add_subtree(ti,ett_zrtp_msg_data);
    dissect_Commit(tvb,pinfo,zrtp_msg_data_tree);
  } else if (!strncmp(message_type,"DHPart1 ",8)){
    ti = proto_tree_add_protocol_format(zrtp_msg_tree,proto_zrtp,tvb,msg_offset+12,linelen-4,"Data");
    zrtp_msg_data_tree = proto_item_add_subtree(ti,ett_zrtp_msg_data);
    dissect_DHPart(tvb,pinfo,zrtp_msg_data_tree,1);
  } else if (!strncmp(message_type,"DHPart2 ",8)){
    ti = proto_tree_add_protocol_format(zrtp_msg_tree,proto_zrtp,tvb,msg_offset+12,linelen-4,"Data");
    zrtp_msg_data_tree = proto_item_add_subtree(ti,ett_zrtp_msg_data);
    dissect_DHPart(tvb,pinfo,zrtp_msg_data_tree,2);
  } else if (!strncmp(message_type,"Confirm1",8)){
    ti = proto_tree_add_protocol_format(zrtp_msg_tree,proto_zrtp,tvb,msg_offset+12,linelen-4,"Data");
    zrtp_msg_data_tree = proto_item_add_subtree(ti,ett_zrtp_msg_data);
    dissect_Confirm(tvb,pinfo,zrtp_msg_data_tree,1);
  } else if (!strncmp(message_type,"Confirm2",8)){
    ti = proto_tree_add_protocol_format(zrtp_msg_tree,proto_zrtp,tvb,msg_offset+12,linelen-4,"Data");
    zrtp_msg_data_tree = proto_item_add_subtree(ti,ett_zrtp_msg_data);
    dissect_Confirm(tvb,pinfo,zrtp_msg_data_tree,2);
  } else if (!strncmp(message_type,"Conf2ACK",8)){
    dissect_Conf2ACK(pinfo);
  } else if (!strncmp(message_type,"Error   ",8)){
    ti = proto_tree_add_protocol_format(zrtp_msg_tree,proto_zrtp,tvb,msg_offset+12,linelen-4,"Data");
    zrtp_msg_data_tree = proto_item_add_subtree(ti,ett_zrtp_msg_data);
    dissect_Error(tvb,pinfo,zrtp_msg_data_tree);
  } else if (!strncmp(message_type,"ErrorACK",8)){
    dissect_ErrorACK(pinfo);
  } else if (!strncmp(message_type,"GoClear ",8)){
    ti = proto_tree_add_protocol_format(zrtp_msg_tree,proto_zrtp,tvb,msg_offset+12,linelen-4,"Data");
    zrtp_msg_data_tree = proto_item_add_subtree(ti,ett_zrtp_msg_data);
    dissect_GoClear(tvb,pinfo,zrtp_msg_data_tree);
  } else if (!strncmp(message_type,"ClearACK",8)){
    dissect_ClearACK(pinfo);
  } else if (!strncmp(message_type,"SASrelay",8)){
    ti = proto_tree_add_protocol_format(zrtp_msg_tree,proto_zrtp,tvb,msg_offset+12,linelen-4,"Data");
    zrtp_msg_data_tree = proto_item_add_subtree(ti,ett_zrtp_msg_data);
    dissect_SASrelay(tvb,pinfo,zrtp_msg_data_tree);
  } else if (!strncmp(message_type,"RelayACK",8)){
    dissect_RelayACK(pinfo);
  } else if (!strncmp(message_type,"Ping    ",8)){
    ti = proto_tree_add_protocol_format(zrtp_msg_tree,proto_zrtp,tvb,msg_offset+12,linelen-4,"Data");
    zrtp_msg_data_tree = proto_item_add_subtree(ti,ett_zrtp_msg_data);
    dissect_Ping(tvb,pinfo,zrtp_msg_data_tree);
  } else if (!strncmp(message_type,"PingACK ",8)){
    ti = proto_tree_add_protocol_format(zrtp_msg_tree,proto_zrtp,tvb,msg_offset+12,linelen-4,"Data");
    zrtp_msg_data_tree = proto_item_add_subtree(ti,ett_zrtp_msg_data);
    dissect_PingACK(tvb,pinfo,zrtp_msg_data_tree);
  }

  sent_crc = tvb_get_ntohl(tvb,msg_offset+checksum_offset);
  calc_crc = ~calculate_crc32c(tvb_get_ptr(tvb,0,msg_offset+checksum_offset),msg_offset+checksum_offset,CRC32C_PRELOAD);

  if (sent_crc == calc_crc) {
    ti = proto_tree_add_uint_format_value(zrtp_tree, hf_zrtp_checksum, tvb, msg_offset+checksum_offset, 4, sent_crc,
                                          "0x%04x [correct]", sent_crc);
    checksum_tree = proto_item_add_subtree(ti, ett_zrtp_checksum);
    ti = proto_tree_add_boolean(checksum_tree, hf_zrtp_checksum_good, tvb, msg_offset+checksum_offset, 4, TRUE);
    PROTO_ITEM_SET_GENERATED(ti);
    ti = proto_tree_add_boolean(checksum_tree, hf_zrtp_checksum_bad, tvb, msg_offset+checksum_offset, 4, FALSE);
    PROTO_ITEM_SET_GENERATED(ti);
  } else {
    ti = proto_tree_add_uint_format_value(zrtp_tree, hf_zrtp_checksum, tvb, msg_offset+checksum_offset, 4, sent_crc,
                                          "0x%04x [incorrect, should be 0x%04x]", sent_crc, calc_crc);
    checksum_tree = proto_item_add_subtree(ti, ett_zrtp_checksum);
    ti = proto_tree_add_boolean(checksum_tree, hf_zrtp_checksum_good, tvb, msg_offset+checksum_offset, 4, FALSE);
    PROTO_ITEM_SET_GENERATED(ti);
    ti = proto_tree_add_boolean(checksum_tree, hf_zrtp_checksum_bad, tvb, msg_offset+checksum_offset, 4, TRUE);
    PROTO_ITEM_SET_GENERATED(ti);
  }

}

static void
dissect_ErrorACK(packet_info *pinfo) {
  if (check_col(pinfo->cinfo, COL_INFO)) {
    col_add_fstr(pinfo->cinfo, COL_INFO, "ErrorACK Packet");
  }
}

static void
dissect_ClearACK(packet_info *pinfo) {
  if (check_col(pinfo->cinfo, COL_INFO)) {
    col_add_fstr(pinfo->cinfo, COL_INFO, "ClearACK Packet");
  }
}

static void
dissect_RelayACK(packet_info *pinfo) {
  if (check_col(pinfo->cinfo, COL_INFO)) {
    col_add_fstr(pinfo->cinfo, COL_INFO, "RelayACK Packet");
  }
}

static void
dissect_Conf2ACK(packet_info *pinfo) {
  if (check_col(pinfo->cinfo, COL_INFO)) {
    col_add_fstr(pinfo->cinfo, COL_INFO, "Conf2ACK Packet");
  }
}

static void
dissect_HelloACK(packet_info *pinfo) {
  if (check_col(pinfo->cinfo, COL_INFO)) {
    col_add_fstr(pinfo->cinfo, COL_INFO, "HelloACK Packet");
  }
}

static void
dissect_Ping(tvbuff_t *tvb, packet_info *pinfo, proto_tree *zrtp_tree) {
  unsigned int data_offset=24;

  if (check_col(pinfo->cinfo, COL_INFO)) {
    col_add_fstr(pinfo->cinfo, COL_INFO, "Ping Packet");
  }

  proto_tree_add_item(zrtp_tree,hf_zrtp_msg_ping_version,tvb,data_offset,4,FALSE);
  proto_tree_add_item(zrtp_tree,hf_zrtp_msg_ping_endpointhash,tvb,data_offset+4,8,FALSE);
}

static void
dissect_PingACK(tvbuff_t *tvb, packet_info *pinfo, proto_tree *zrtp_tree) {
  unsigned int data_offset=24;

  if (check_col(pinfo->cinfo, COL_INFO)) {
    col_add_fstr(pinfo->cinfo, COL_INFO, "PingACK Packet");
  }

  proto_tree_add_item(zrtp_tree,hf_zrtp_msg_ping_version,tvb,data_offset,4,FALSE);
  proto_tree_add_item(zrtp_tree,hf_zrtp_msg_pingack_endpointhash,tvb,data_offset+4,8,FALSE);
  proto_tree_add_item(zrtp_tree,hf_zrtp_msg_ping_endpointhash,tvb,data_offset+12,8,FALSE);
  proto_tree_add_item(zrtp_tree,hf_zrtp_msg_ping_ssrc,tvb,data_offset+20,4,FALSE);
}

static void
dissect_GoClear(tvbuff_t *tvb, packet_info *pinfo, proto_tree *zrtp_tree) {
  unsigned int data_offset=24;

  if (check_col(pinfo->cinfo, COL_INFO)) {
    col_add_fstr(pinfo->cinfo, COL_INFO, "GoClear Packet");
  }

  proto_tree_add_item(zrtp_tree,hf_zrtp_msg_hmac,tvb,data_offset+0,8,FALSE);
}

static void
dissect_Error(tvbuff_t *tvb, packet_info *pinfo, proto_tree *zrtp_tree) {
  unsigned int data_offset=24;

  if (check_col(pinfo->cinfo, COL_INFO)) {
    col_add_fstr(pinfo->cinfo, COL_INFO, "Error Packet");
  }

  proto_tree_add_item(zrtp_tree,hf_zrtp_msg_error,tvb,data_offset,4,FALSE);
}

static void
dissect_Confirm(tvbuff_t *tvb, packet_info *pinfo, proto_tree *zrtp_tree,int part) {
  proto_item   *ti;
  unsigned int data_offset=24;
  proto_tree *zrtp_msg_encrypted_tree;
  int linelen;

  if (check_col(pinfo->cinfo, COL_INFO)) {
    col_add_fstr(pinfo->cinfo, COL_INFO, (part == 1) ? "Confirm1 Packet" : "Confirm2 Packet");
  }

  proto_tree_add_item(zrtp_tree,hf_zrtp_msg_hmac,tvb,data_offset+0,8,FALSE);
  proto_tree_add_item(zrtp_tree,hf_zrtp_msg_cfb,tvb,data_offset+8,16,FALSE);
  linelen = tvb_reported_length_remaining(tvb,data_offset+24);
  ti = proto_tree_add_protocol_format(zrtp_tree,proto_zrtp,tvb,data_offset+24,linelen-4,"Encrypted Data");
  zrtp_msg_encrypted_tree = proto_item_add_subtree(ti,ett_zrtp_msg_encrypted);
}

static void
dissect_SASrelay(tvbuff_t *tvb, packet_info *pinfo, proto_tree *zrtp_tree) {
  proto_item   *ti;
  unsigned int data_offset=24;
  proto_tree *zrtp_msg_encrypted_tree;
  int linelen;

  if (check_col(pinfo->cinfo, COL_INFO)) {
    col_add_fstr(pinfo->cinfo, COL_INFO, "SASrelay Packet");
  }

  proto_tree_add_item(zrtp_tree,hf_zrtp_msg_hmac,tvb,data_offset+0,8,FALSE);
  proto_tree_add_item(zrtp_tree,hf_zrtp_msg_cfb,tvb,data_offset+8,16,FALSE);
  linelen = tvb_reported_length_remaining(tvb,data_offset+24);
  ti = proto_tree_add_protocol_format(zrtp_tree,proto_zrtp,tvb,data_offset+24,linelen-4,"Encrypted Data");
  zrtp_msg_encrypted_tree = proto_item_add_subtree(ti,ett_zrtp_msg_encrypted);
}

static void
dissect_DHPart(tvbuff_t *tvb, packet_info *pinfo, proto_tree *zrtp_tree,int part) {
  proto_item   *ti;
  unsigned int msg_offset=12;
  unsigned int data_offset=56;
  proto_tree *zrtp_msg_pvr_tree;
  int linelen, pvr_len;

  if (check_col(pinfo->cinfo, COL_INFO)) {
    col_add_fstr(pinfo->cinfo, COL_INFO, (part == 1) ? "DHPart1 Packet" : "DHPart2 Packet");
  }

  proto_tree_add_item(zrtp_tree,hf_zrtp_msg_hash_image,tvb,msg_offset+12,32,FALSE);
  proto_tree_add_item(zrtp_tree,hf_zrtp_msg_rs1ID,tvb,data_offset+0,8,FALSE);
  proto_tree_add_item(zrtp_tree,hf_zrtp_msg_rs2ID,tvb,data_offset+8,8,FALSE);
  proto_tree_add_item(zrtp_tree,hf_zrtp_msg_auxs,tvb,data_offset+16,8,FALSE);
  proto_tree_add_item(zrtp_tree,hf_zrtp_msg_pbxs,tvb,data_offset+24,8,FALSE);
  linelen = tvb_reported_length_remaining(tvb,data_offset+32);
  pvr_len = linelen-8-4;
  ti = proto_tree_add_protocol_format(zrtp_tree,proto_zrtp,tvb,data_offset+32,pvr_len,(part==1)?"pvr Data":"pvi Data");
  zrtp_msg_pvr_tree = proto_item_add_subtree(ti,ett_zrtp_msg_pvr);
  proto_tree_add_item(zrtp_tree,hf_zrtp_msg_hmac,tvb,data_offset+32+pvr_len,8,FALSE);
}

static void
dissect_Commit(tvbuff_t *tvb, packet_info *pinfo, proto_tree *zrtp_tree) {
  unsigned int msg_offset=12;
  unsigned int data_offset=56;
  unsigned char value[5];
  int key_type = 0;
  /*
    0 - other type
    1 - "Mult"
    2 - "Prsh"
  */
  unsigned int offset;

  if (check_col(pinfo->cinfo, COL_INFO)) {
    col_add_fstr(pinfo->cinfo, COL_INFO, "Commit Packet");
  }

  proto_tree_add_item(zrtp_tree,hf_zrtp_msg_hash_image,tvb,msg_offset+12,32,FALSE);
  /* ZID */
  proto_tree_add_item(zrtp_tree,hf_zrtp_msg_zid,tvb,data_offset+0,12,FALSE);
  tvb_memcpy(tvb,(void *)value,data_offset+12,4);
  value[4]='\0';
  proto_tree_add_string_format(zrtp_tree,hf_zrtp_msg_hash,tvb,data_offset+12,4,value,
				  "Hash: %s",key_to_val(value,4,zrtp_hash_type_vals,"Unknown hash type %s"));
  tvb_memcpy(tvb,(void *)value,data_offset+16,4);
  value[4]='\0';
  proto_tree_add_string_format(zrtp_tree,hf_zrtp_msg_cipher,tvb,data_offset+16,4,value,"Cipher: %s",
				  key_to_val(value,4,zrtp_cipher_type_vals,"Unknown cipher type %s"));
  tvb_memcpy(tvb,(void *)value,data_offset+20,4);
  value[4]='\0';
  proto_tree_add_string_format(zrtp_tree,hf_zrtp_msg_at,tvb,data_offset+20,4,value,
				  "Auth tag: %s",key_to_val(value,4,zrtp_auth_tag_vals,"Unknown auth tag %s"));
  tvb_memcpy(tvb,(void *)value,data_offset+24,4);
  value[4]='\0';
  proto_tree_add_string_format(zrtp_tree,hf_zrtp_msg_keya,tvb,data_offset+24,4,value,
				  "Key agreement: %s",key_to_val(value,4,zrtp_key_agreement_vals,"Unknown key agreement %s"));

  if(!strncmp(value, "Mult", 4)){
    key_type = 1;
  } else if (!strncmp(value, "Prsh", 4)){
    key_type = 2;
  }
  tvb_memcpy(tvb,(void *)value,data_offset+28,4);
  value[4]='\0';
  proto_tree_add_string_format(zrtp_tree,hf_zrtp_msg_sas,tvb,data_offset+28,4,value,
				  "SAS type: %s",key_to_val(value,4,zrtp_sas_type_vals,"Unknown SAS type %s"));

  switch(key_type){
  case 1: /* 
	     Mult
	  */
    proto_tree_add_item(zrtp_tree,hf_zrtp_msg_nonce,tvb,data_offset+32,16,FALSE);
    offset = 48;
    break;
  case 2: /*
	    Prsh
	  */
    proto_tree_add_item(zrtp_tree,hf_zrtp_msg_nonce,tvb,data_offset+32,16,FALSE);
    proto_tree_add_item(zrtp_tree,hf_zrtp_msg_key_id,tvb,data_offset+48,8,FALSE);
    offset = 56;
    break;
  default: /*
	     other
	   */
    proto_tree_add_item(zrtp_tree,hf_zrtp_msg_hvi,tvb,data_offset+32, 32, FALSE);
    offset = 64;
    break;
  }

  proto_tree_add_item(zrtp_tree,hf_zrtp_msg_hmac,tvb,data_offset+offset,8,FALSE);
}

static void
dissect_Hello(tvbuff_t *tvb, packet_info *pinfo, proto_tree *zrtp_tree) {
  proto_item   *ti;
  unsigned int msg_offset = 12;
  unsigned int data_offset = 88;
  guint8       val_b;
  unsigned int i;
  unsigned int run_offset;
  unsigned int hc,cc,ac,kc,sc;
  unsigned int vhc,vcc,vac,vkc,vsc;
  unsigned char value[5];
  unsigned char version_str[5];
  proto_tree *tmp_tree;

  if (check_col(pinfo->cinfo, COL_INFO)) {
    col_add_fstr(pinfo->cinfo, COL_INFO, "Hello Packet");
  }

  tvb_memcpy(tvb,version_str,msg_offset+12,4);
  version_str[4]='\0';
  if (check_valid_version(version_str) == NULL){
    if (check_col(pinfo->cinfo, COL_INFO)) {
      col_add_fstr(pinfo->cinfo, COL_INFO, "Unsupported version of ZRTP protocol");
    }
  }
  proto_tree_add_item(zrtp_tree,hf_zrtp_msg_version,tvb,msg_offset+12,4,FALSE);
  proto_tree_add_item(zrtp_tree,hf_zrtp_msg_client_id,tvb,msg_offset+16,16,FALSE);
  proto_tree_add_item(zrtp_tree,hf_zrtp_msg_hash_image,tvb,msg_offset+32,32,FALSE);
  proto_tree_add_item(zrtp_tree,hf_zrtp_msg_zid,tvb,msg_offset+64,12,FALSE);
  proto_tree_add_item(zrtp_tree,hf_zrtp_msg_mitm,tvb,data_offset+0,1,FALSE);
  proto_tree_add_item(zrtp_tree,hf_zrtp_msg_passive,tvb,data_offset+0,1,FALSE);

  val_b = tvb_get_guint8(tvb,data_offset+1);
  hc = val_b & 0x0F;
  vhc = hc;

  val_b = tvb_get_guint8(tvb,data_offset+2);
  cc = val_b & 0xF0;
  ac = val_b & 0x0F;
  vcc = cc >> 4;
  vac = ac;

  val_b = tvb_get_guint8(tvb,data_offset+3);
  kc = val_b & 0xF0;
  sc = val_b & 0x0F;
  vkc = kc >> 4;
  vsc = sc;

  ti=proto_tree_add_uint_format(zrtp_tree,hf_zrtp_msg_hash_count,tvb,data_offset+1,1,hc,"Hash type count = %d",vhc);
  tmp_tree = proto_item_add_subtree(ti,ett_zrtp_msg_hc);
  run_offset = data_offset+4;
  for(i=0;i<vhc;i++){
    tvb_memcpy(tvb,(void *)value,run_offset,4);
    value[4]='\0';
    proto_tree_add_string_format(tmp_tree,hf_zrtp_msg_hash,tvb,run_offset,4,value,
				    "Hash[%d]: %s",i,key_to_val(value,4,zrtp_hash_type_vals,"Unknown hash type %s"));
    run_offset+=4;
  }
  ti=proto_tree_add_uint_format(zrtp_tree,hf_zrtp_msg_cipher_count,tvb,data_offset+2,1,cc,"Cipher type count = %d",vcc);
  tmp_tree = proto_item_add_subtree(ti,ett_zrtp_msg_cc);
  for(i=0;i<vcc;i++){
    tvb_memcpy(tvb,(void *)value,run_offset,4);
    value[4]='\0';
    proto_tree_add_string_format(tmp_tree,hf_zrtp_msg_cipher,tvb,run_offset,4,value,"Cipher[%d]: %s",i,
				    key_to_val(value,4,zrtp_cipher_type_vals,"Unknown cipher type %s"));
    run_offset+=4;
  }
  ti=proto_tree_add_uint_format(zrtp_tree,hf_zrtp_msg_authtag_count,tvb,data_offset+2,1,ac,"Auth tag count = %d",vac);
  tmp_tree = proto_item_add_subtree(ti,ett_zrtp_msg_ac);  
  for(i=0;i<vac;i++){
    tvb_memcpy(tvb,(void *)value,run_offset,4);
    value[4]='\0';
    proto_tree_add_string_format(tmp_tree,hf_zrtp_msg_at,tvb,run_offset,4,value,
				    "Auth tag[%d]: %s",i,key_to_val(value,4,zrtp_auth_tag_vals,"Unknown auth tag %s"));
    run_offset+=4;
  }
  ti=proto_tree_add_uint_format(zrtp_tree,hf_zrtp_msg_key_count,tvb,data_offset+3,1,kc,"Key agreement type count = %d",vkc);
  tmp_tree = proto_item_add_subtree(ti,ett_zrtp_msg_kc);  
  for(i=0;i<vkc;i++){
    tvb_memcpy(tvb,(void *)value,run_offset,4);
    value[4]='\0';
    proto_tree_add_string_format(tmp_tree,hf_zrtp_msg_keya,tvb,run_offset,4,value,
				    "Key agreement[%d]: %s",i,key_to_val(value,4,zrtp_key_agreement_vals,"Unknown key agreement %s"));
    run_offset+=4;
  }
  ti=proto_tree_add_uint_format(zrtp_tree,hf_zrtp_msg_sas_count,tvb,data_offset+3,1,sc,"SAS type count = %d",vsc);
  tmp_tree = proto_item_add_subtree(ti,ett_zrtp_msg_sc);  
  for(i=0;i<vsc;i++){
    tvb_memcpy(tvb,(void *)value,run_offset,4);
    value[4]='\0';
    proto_tree_add_string_format(tmp_tree,hf_zrtp_msg_sas,tvb,run_offset,4,value,
				    "SAS type[%d]: %s",i,key_to_val(value,4,zrtp_sas_type_vals,"Unknown SAS type %s"));
    run_offset+=4;
  }

  proto_tree_add_item(zrtp_tree,hf_zrtp_msg_hmac,tvb,run_offset,8,FALSE);
}

void
proto_register_zrtp(void)
{
  static hf_register_info hf[] = {
    {&hf_zrtp_rtpversion,
     {
       "RTP Version", "zrtp.rtpversion",
       FT_UINT8, BASE_DEC,
       NULL, 0xC0,
       NULL, HFILL
     }
    },

    {&hf_zrtp_rtppadding,
     {
       "RTP padding", "zrtp.rtppadding",
       FT_BOOLEAN, 8,
       NULL, 0x20,
       NULL, HFILL
     }
    },

    {&hf_zrtp_rtpextension,
     {
       "RTP Extension", "zrtp.rtpextension",
       FT_BOOLEAN, 8,
       NULL, 0x10,
       NULL, HFILL
     }
    },

    {&hf_zrtp_id,
     {
       "ID", "zrtp.id",
       FT_UINT8, BASE_HEX,
       NULL, 0x0,
       NULL, HFILL
     }
    },

    {&hf_zrtp_sequence,
     {
       "Sequence", "zrtp.sequence",
       FT_UINT16, BASE_DEC,
       NULL, 0x0,
       NULL, HFILL
     }
    },

    {&hf_zrtp_cookie,
     {
       "Magic Cookie", "zrtp.cookie",
       FT_STRING, BASE_NONE,
       NULL, 0x0,
       NULL, HFILL
     }
    },

    {&hf_zrtp_source_id,
     {
       "Source Identifier", "zrtp.source_id",
       FT_UINT32, BASE_HEX,
       NULL, 0x0,
       NULL, HFILL
     }
    },

    /*
       Message Types
    */
    {&hf_zrtp_signature,
     {
       "Signature", "zrtp.signature",
       FT_UINT16, BASE_HEX,
       NULL, 0x0,
       NULL, HFILL
     }
    },

    {&hf_zrtp_msg_length,
     {
       "Length", "zrtp.length",
       FT_UINT16, BASE_DEC,
       NULL, 0x0,
       NULL, HFILL
     }
    },

    {&hf_zrtp_msg_type,
     {
       "Type", "zrtp.type",
       FT_STRING, BASE_NONE,
       NULL, 0x0,
       NULL, HFILL
     }
    },

    {&hf_zrtp_msg_version,
     {
       "ZRTP protocol version", "zrtp.version",
       FT_STRING, BASE_NONE,
       NULL, 0x0,
       NULL, HFILL
     }
    },

    {&hf_zrtp_msg_client_id,
     {
       "Client Identifier", "zrtp.client_source_id",
       FT_STRING, BASE_NONE,
       NULL, 0x0,
       NULL, HFILL
     }
    },

    {&hf_zrtp_msg_hash_image,
     {
       "Hash Image", "zrtp.hash_image",
       FT_BYTES, BASE_NONE,
       NULL, 0x0,
       NULL, HFILL
     }
    },

    {&hf_zrtp_msg_zid,
     {
       "ZID", "zrtp.zid",
       FT_BYTES, BASE_DEC,
       NULL, 0x0,
       NULL, HFILL
     }
    },

    {&hf_zrtp_msg_mitm,
     {
       "MiTM", "zrtp.mitm",
       FT_BOOLEAN, 8,
       NULL, 0x20,
       NULL, HFILL
     }
    },

    {&hf_zrtp_msg_passive,
     {
       "Passive", "zrtp.passive",
       FT_BOOLEAN, 8,
       NULL, 0x10,
       NULL, HFILL
     }
    },

    {&hf_zrtp_msg_hash_count,
     {
       "Hash Count", "zrtp.hc",
       FT_UINT8, BASE_DEC,
       NULL, 0x0F,
       NULL, HFILL
     }
    },

    {&hf_zrtp_msg_cipher_count,
     {
       "Cipher Count", "zrtp.cc",
       FT_UINT8, BASE_DEC,
       NULL, 0xF0,
       NULL, HFILL
     }
    },

    {&hf_zrtp_msg_authtag_count,
     {
       "Auth tag Count", "zrtp.ac",
       FT_UINT8, BASE_DEC,
       NULL, 0x0F,
       NULL, HFILL
     }
    },

    {&hf_zrtp_msg_key_count,
     {
       "Key Agreement Count", "zrtp.kc",
       FT_UINT8, BASE_DEC,
       NULL, 0xF0,
       NULL, HFILL
     }
    },

    {&hf_zrtp_msg_sas_count,
     {
       "SAS Count", "zrtp.sc",
       FT_UINT8, BASE_DEC,
       NULL, 0x0F,
       NULL, HFILL
     }
    },

    {&hf_zrtp_msg_hash,
     {
       "Hash", "zrtp.hash",
       FT_STRING, BASE_NONE,
       NULL, 0x0,
       NULL, HFILL
     }
    },

    {&hf_zrtp_msg_cipher,
     {
       "Cipher", "zrtp.cipher",
       FT_STRING, BASE_NONE,
       NULL, 0x0,
       NULL, HFILL
     }
    },

    {&hf_zrtp_msg_at,
     {
       "AT", "zrtp.at",
       FT_STRING, BASE_NONE,
       NULL, 0x0,
       NULL, HFILL
     }
    },

    {&hf_zrtp_msg_keya,
     {
       "Key Agreement", "zrtp.keya",
       FT_STRING, BASE_NONE,
       NULL, 0x0,
       NULL, HFILL
     }
    },

    {&hf_zrtp_msg_sas,
     {
       "SAS", "zrtp.sas",
       FT_STRING, BASE_NONE,
       NULL, 0x0,
       NULL, HFILL
     }
    },

    {&hf_zrtp_msg_rs1ID,
     {
       "rs1ID", "zrtp.rs1id",
       FT_BYTES, BASE_NONE,
       NULL, 0x0,
       NULL, HFILL 
     }
    },

    {&hf_zrtp_msg_rs2ID,
     {
       "rs2ID", "zrtp.rs2id",
       FT_BYTES, BASE_NONE,
       NULL, 0x0,
       NULL, HFILL
     }
    },

    {&hf_zrtp_msg_auxs,
     {
       "auxs", "zrtp.auxs",
       FT_BYTES, BASE_NONE,
       NULL, 0x0,
       NULL, HFILL
     }
    },

    {&hf_zrtp_msg_pbxs,
     {
       "pbxs", "zrtp.pbxs",
       FT_BYTES, BASE_NONE,
       NULL, 0x0,
       NULL, HFILL
     }
    },

    {&hf_zrtp_msg_hmac,
     {
       "HMAC", "zrtp.hmac",
       FT_BYTES, BASE_NONE,
       NULL, 0x0,
       NULL, HFILL
     }
    },

    {&hf_zrtp_msg_cfb,
     {
       "CFB", "zrtp.cfb",
       FT_BYTES, BASE_NONE,
       NULL, 0x0,
       NULL, HFILL
     }
    },

    {&hf_zrtp_msg_error,
     {
       "Error", "zrtp.error",
       FT_UINT32, BASE_DEC,
       VALS(zrtp_error_vals), 0x0,
       NULL, HFILL
     }
    },

    {&hf_zrtp_msg_ping_version,
     {
       "Ping Version", "zrtp.ping_version",
       FT_STRING, BASE_NONE,
       NULL, 0x0,
       NULL, HFILL
     }
    },

    {&hf_zrtp_msg_ping_endpointhash,
     {
       "Ping Endpoint Hash", "zrtp.ping_endpointhash",
       FT_UINT64, BASE_HEX,
       NULL, 0x0,
       NULL, HFILL
     }
    },

    {&hf_zrtp_msg_pingack_endpointhash,
     {
       "PingAck Endpoint Hash", "zrtp.pingack_endpointhash",
       FT_UINT64, BASE_HEX,
       NULL, 0x0,
       NULL, HFILL
     }
    },

    {&hf_zrtp_msg_ping_ssrc,
     {
       "Ping SSRC", "zrtp.ping_ssrc",
       FT_UINT32, BASE_HEX,
       NULL, 0x0,
       NULL, HFILL
     }
    },

    {&hf_zrtp_checksum,
     {
       "Checksum", "zrtp.checksum",
       FT_UINT32, BASE_HEX,
       NULL, 0x0,
       NULL, HFILL
     }
    },

    {&hf_zrtp_checksum_good,
     {
       "Good", "zrtp.checksum_good",
       FT_BOOLEAN, BASE_NONE,
       NULL, 0x0,
       "True: checksum matches packet content; False: doesn't match content", HFILL
     }
    },

    {&hf_zrtp_checksum_bad,
     {
       "Bad", "zrtp.checksum_bad",
       FT_BOOLEAN, BASE_NONE,
       NULL, 0x0,
       "True: checksum doesn't match packet content; False: matches content", HFILL
     }
    },

    {&hf_zrtp_msg_hvi,
     {
       "hvi", "zrtp.hvi",
       FT_BYTES, BASE_NONE,
       NULL, 0x0,
       NULL, HFILL
     }
    },

    {&hf_zrtp_msg_nonce,
     {
       "nonce", "zrtp.nonce",
       FT_BYTES, BASE_NONE,
       NULL, 0x0,
       NULL, HFILL
     }
    },

    {&hf_zrtp_msg_key_id,
     {
       "key ID", "zrtp.key_id",
       FT_BYTES, BASE_NONE,
       NULL, 0x0,
       NULL, HFILL
     }
    }
  };

  static gint *ett[] = {
    &ett_zrtp,
    &ett_zrtp_msg,
    &ett_zrtp_msg_data,
    &ett_zrtp_msg_encrypted,
    &ett_zrtp_msg_pvr,
    &ett_zrtp_msg_hc,
    &ett_zrtp_msg_kc,
    &ett_zrtp_msg_ac,
    &ett_zrtp_msg_cc,
    &ett_zrtp_msg_sc,
    &ett_zrtp_checksum
  };

  proto_zrtp = proto_register_protocol("ZRTP", "ZRTP", "zrtp");
  proto_register_field_array(proto_zrtp, hf, array_length(hf));
  proto_register_subtree_array(ett, array_length(ett));
  register_dissector("zrtp", dissect_zrtp, proto_zrtp);
}

void
proto_reg_handoff_zrtp(void)
{
  dissector_handle_t zrtp_handle;

  zrtp_handle = find_dissector("zrtp");
  dissector_add_handle("udp.port", zrtp_handle);
}
