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/* packet-ntp.c
* Routines for NTP packet dissection
* Copyright 1999, Nathan Neulinger <nneul@umr.edu>
*
* $Id: packet-ntp.c,v 1.37 2002/08/28 21:00:24 jmayer Exp $
*
* Ethereal - Network traffic analyzer
* By Gerald Combs <gerald@ethereal.com>
* Copyright 1998 Gerald Combs
*
* Copied from packet-tftp.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 <time.h>
#include <math.h>
#include <glib.h>
#ifdef NEED_SNPRINTF_H
# include "snprintf.h"
#endif
#include <epan/packet.h>
#include <epan/resolv.h>
#include "packet-ntp.h"
/*
* Dissecting NTP packets version 3 and 4 (RFC2030, RFC1769, RFC1361,
* RFC1305).
*
* Those packets have simple structure:
* 1 2 3
* 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
* +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
* |LI | VN |Mode | Stratum | Poll | Precision |
* +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
* | Root Delay |
* +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
* | Root Dispersion |
* +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
* | Reference Identifier |
* +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
* | Reference Timestamp (64) |
* | |
* +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
* | Originate Timestamp (64) |
* | |
* +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
* | Receive Timestamp (64) |
* | |
* +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
* | Transmit Timestamp (64) |
* | |
* +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
* | Key Identifier (optional) (32) |
* +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
* | Message Digest (optional) (128) |
* | |
* | |
* | |
* +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
* NTP timestamps are represented as a 64-bit unsigned fixed-point number,
* in seconds relative to 0h on 1 January 1900. The integer part is in the
* first 32 bits and the fraction part in the last 32 bits.
*/
#define UDP_PORT_NTP 123
#define TCP_PORT_NTP 123
/* Leap indicator, 2bit field is used to warn of a inserted/deleted
* second, or to alarm loosed synchronization.
*/
#define NTP_LI_MASK 0xC0
#define NTP_LI_NONE 0
#define NTP_LI_61 1
#define NTP_LI_59 2
#define NTP_LI_ALARM 3
static const value_string li_types[] = {
{ NTP_LI_NONE, "no warning" },
{ NTP_LI_61, "last minute has 61 seconds" },
{ NTP_LI_59, "last minute has 59 seconds" },
{ NTP_LI_ALARM, "alarm condition (clock not synchronized)" },
{ 0, NULL}
};
/* Version info, 3bit field informs about NTP version used in particular
* packet. According to rfc2030, version info could be only 3 or 4, but I
* have noticed packets with 1 or even 6 as version numbers. They are
* produced as a result of ntptrace command. Are those packets mailformed
* on purpose? I don't know yet, probably some browsing through ntp sources
* would help. My solution is to put them as reserved for now.
*/
#define NTP_VN_MASK 0x38
static const value_string ver_nums[] = {
{ 0, "reserved" },
{ 1, "reserved" },
{ 2, "reserved" },
{ 3, "NTP Version 3" },
{ 4, "NTP Version 4" },
{ 5, "reserved" },
{ 6, "reserved" },
{ 7, "reserved" },
{ 0, NULL}
};
/* Mode, 3bit field representing mode of comunication.
*/
#define NTP_MODE_MASK 7
#define NTP_MODE_RSV 0
#define NTP_MODE_SYMACT 1
#define NTP_MODE_SYMPAS 2
#define NTP_MODE_CLIENT 3
#define NTP_MODE_SERVER 4
#define NTP_MODE_BCAST 5
#define NTP_MODE_CTRL 6
#define NTP_MODE_PRIV 7
static const value_string mode_types[] = {
{ NTP_MODE_RSV, "reserved" },
{ NTP_MODE_SYMACT, "symmetric active" },
{ NTP_MODE_SYMPAS, "symmetric passive" },
{ NTP_MODE_CLIENT, "client" },
{ NTP_MODE_SERVER, "server" },
{ NTP_MODE_BCAST, "broadcast" },
{ NTP_MODE_CTRL, "reserved for NTP control message"},
{ NTP_MODE_PRIV, "reserved for private use" },
{ 0, NULL}
};
/* According to rfc, primary (stratum-0 and stratum-1) servers should set
* their Reference Clock ID (4bytes field) according to following table:
*/
static const struct {
char *id;
char *data;
} primary_sources[] = {
{ "LOCL", "uncalibrated local clock" },
{ "PPS\0", "atomic clock or other pulse-per-second source" },
{ "ACTS", "NIST dialup modem service" },
{ "USNO", "USNO modem service" },
{ "PTB\0", "PTB (Germany) modem service" },
{ "TDF\0", "Allouis (France) Radio 164 kHz" },
{ "DCF\0", "Mainflingen (Germany) Radio 77.5 kHz" },
{ "MSF\0", "Rugby (UK) Radio 60 kHz" },
{ "WWV\0", "Ft. Collins (US) Radio 2.5, 5, 10, 15, 20 MHz" },
{ "WWVB", "Boulder (US) Radio 60 kHz" },
{ "WWVH", "Kaui Hawaii (US) Radio 2.5, 5, 10, 15 MHz" },
{ "CHU\0", "Ottawa (Canada) Radio 3330, 7335, 14670 kHz" },
{ "LORC", "LORAN-C radionavigation system" },
{ "OMEG", "OMEGA radionavigation system" },
{ "GPS\0", "Global Positioning Service" },
{ "GOES", "Geostationary Orbit Environment Satellite" },
{ "DCN\0", "DCN routing protocol" },
{ "NIST", "NIST public modem" },
{ "TSP\0", "TSP time protocol" },
{ "DTS\0", "Digital Time Service" },
{ "ATOM", "Atomic clock (calibrated)" },
{ "VLF\0", "VLF radio (OMEGA,, etc.)" },
{ "IRIG", "IRIG-B timecode" },
{ "1PPS", "External 1 PPS input" },
{ "FREE", "(Internal clock)" },
{ NULL, NULL}
};
static int proto_ntp = -1;
static int hf_ntp_flags = -1;
static int hf_ntp_flags_li = -1;
static int hf_ntp_flags_vn = -1;
static int hf_ntp_flags_mode = -1;
static int hf_ntp_stratum = -1;
static int hf_ntp_ppoll = -1;
static int hf_ntp_precision = -1;
static int hf_ntp_rootdelay = -1;
static int hf_ntp_rootdispersion = -1;
static int hf_ntp_refid = -1;
static int hf_ntp_reftime = -1;
static int hf_ntp_org = -1;
static int hf_ntp_rec = -1;
static int hf_ntp_xmt = -1;
static int hf_ntp_keyid = -1;
static int hf_ntp_mac = -1;
static gint ett_ntp = -1;
static gint ett_ntp_flags = -1;
/* ntp_fmt_ts - converts NTP timestamp to human readable string.
* reftime - 64bit timestamp (IN)
* buff - string buffer for result (OUT)
* returns pointer to filled buffer.
*/
static char *
ntp_fmt_ts(const guint8 *reftime, char* buff)
{
guint32 tempstmp, tempfrac;
time_t temptime;
struct tm *bd;
double fractime;
tempstmp = pntohl(&reftime[0]);
tempfrac = pntohl(&reftime[4]);
if ((tempstmp == 0) && (tempfrac == 0)) {
strcpy (buff, "NULL");
return buff;
} else {
temptime = tempstmp - (guint32) NTP_BASETIME;
bd = gmtime(&temptime);
if (bd != NULL) {
fractime = bd->tm_sec + tempfrac / 4294967296.0;
snprintf(buff, NTP_TS_SIZE,
"%04d-%02d-%02d %02d:%02d:%07.4f UTC",
bd->tm_year + 1900, bd->tm_mon + 1, bd->tm_mday,
bd->tm_hour, bd->tm_min, fractime);
} else
strncpy(buff, "Not representable", NTP_TS_SIZE);
}
return buff;
}
/* dissect_ntp - dissects NTP packet data
* tvb - tvbuff for packet data (IN)
* pinfo - packet info
* proto_tree - resolved protocol tree
*/
static void
dissect_ntp(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree)
{
proto_tree *ntp_tree, *flags_tree;
proto_item *ti, *tf;
guint8 flags;
guint8 stratum;
guint8 ppoll;
gint8 precision;
double rootdelay;
double rootdispersion;
const guint8 *refid;
guint32 refid_addr;
const guint8 *reftime;
const guint8 *org;
const guint8 *rec;
const guint8 *xmt;
gchar buff[NTP_TS_SIZE];
int i;
if (check_col(pinfo->cinfo, COL_PROTOCOL))
col_set_str(pinfo->cinfo, COL_PROTOCOL, "NTP");
if (check_col(pinfo->cinfo, COL_INFO))
col_set_str(pinfo->cinfo, COL_INFO, "NTP");
if (tree) {
/* Adding NTP item and subtree */
ti = proto_tree_add_item(tree, proto_ntp, tvb, 0, -1, FALSE);
ntp_tree = proto_item_add_subtree(ti, ett_ntp);
flags = tvb_get_guint8(tvb, 0);
tf = proto_tree_add_uint(ntp_tree, hf_ntp_flags, tvb, 0, 1,
flags);
/* Adding flag subtree and items */
flags_tree = proto_item_add_subtree(tf, ett_ntp_flags);
proto_tree_add_uint(flags_tree, hf_ntp_flags_li, tvb, 0, 1,
flags);
proto_tree_add_uint(flags_tree, hf_ntp_flags_vn, tvb, 0, 1,
flags);
proto_tree_add_uint(flags_tree, hf_ntp_flags_mode, tvb, 0, 1,
flags);
/* Stratum, 1byte field represents distance from primary source
*/
stratum = tvb_get_guint8(tvb, 1);
if (stratum == 0) {
strcpy (buff, "Peer Clock Stratum: unspecified or unavailable (%u)");
} else if (stratum == 1) {
strcpy (buff, "Peer Clock Stratum: primary reference (%u)");
} else if ((stratum >= 2) && (stratum <= 15)) {
strcpy (buff, "Peer Clock Stratum: secondary reference (%u)");
} else {
strcpy (buff, "Peer Clock Stratum: reserved: %u");
}
proto_tree_add_uint_format(ntp_tree, hf_ntp_stratum, tvb, 1, 1,
stratum, buff, stratum);
/* Poll interval, 1byte field indicating the maximum interval
* between successive messages, in seconds to the nearest
* power of two.
*/
ppoll = tvb_get_guint8(tvb, 2);
proto_tree_add_uint_format(ntp_tree, hf_ntp_ppoll, tvb, 2, 1,
ppoll,
(((ppoll >= 4) && (ppoll <= 16)) ?
"Peer Polling Interval: %u (%u sec)" :
"Peer Polling Interval: invalid (%u)"),
ppoll,
1 << ppoll);
/* Precision, 1byte field indicating the precision of the
* local clock, in seconds to the nearest power of two.
*/
precision = tvb_get_guint8(tvb, 3);
proto_tree_add_uint_format(ntp_tree, hf_ntp_precision, tvb, 3, 1,
precision,
"Peer Clock Precision: %8.6f sec",
pow(2, precision));
/* Root Delay is a 32-bit signed fixed-point number indicating
* the total roundtrip delay to the primary reference source,
* in seconds with fraction point between bits 15 and 16.
*/
rootdelay = ((gint16)tvb_get_ntohs(tvb, 4)) +
(tvb_get_ntohs(tvb, 6) / 65536.0);
proto_tree_add_double_format(ntp_tree, hf_ntp_rootdelay, tvb, 4, 4,
rootdelay,
"Root Delay: %9.4f sec",
rootdelay);
/* Root Dispersion, 32-bit unsigned fixed-point number indicating
* the nominal error relative to the primary reference source, in
* seconds with fraction point between bits 15 and 16.
*/
rootdispersion = ((gint16)tvb_get_ntohs(tvb, 8)) +
(tvb_get_ntohs(tvb, 10) / 65536.0);
proto_tree_add_double_format(ntp_tree, hf_ntp_rootdispersion, tvb, 8, 4,
rootdispersion,
"Clock Dispersion: %9.4f sec",
rootdispersion);
/* Now, there is a problem with secondary servers. Standards
* asks from stratum-2 - stratum-15 servers to set this to the
* low order 32 bits of the latest transmit timestamp of the
* reference source.
* But, all V3 and V4 servers set this to IP adress of their
* higher level server. My decision was to resolve this address.
*/
refid = tvb_get_ptr(tvb, 12, 4);
if (stratum <= 1) {
snprintf (buff, sizeof buff,
"Unindentified reference source '%.4s'",
refid);
for (i = 0; primary_sources[i].id; i++) {
if (memcmp (refid, primary_sources[i].id,
4) == 0) {
strcpy (buff, primary_sources[i].data);
break;
}
}
} else {
buff[sizeof(buff) - 1] = '\0';
tvb_memcpy(tvb, (guint8 *)&refid_addr, 12, 4);
strncpy (buff, get_hostname (refid_addr),
sizeof(buff));
if (buff[sizeof(buff) - 1] != '\0')
strcpy(&buff[sizeof(buff) - 4], "...");
}
proto_tree_add_bytes_format(ntp_tree, hf_ntp_refid, tvb, 12, 4,
refid,
"Reference Clock ID: %s", buff);
/* Reference Timestamp: This is the time at which the local clock was
* last set or corrected.
*/
reftime = tvb_get_ptr(tvb, 16, 8);
proto_tree_add_bytes_format(ntp_tree, hf_ntp_reftime, tvb, 16, 8,
reftime,
"Reference Clock Update Time: %s",
ntp_fmt_ts(reftime, buff));
/* Originate Timestamp: This is the time at which the request departed
* the client for the server.
*/
org = tvb_get_ptr(tvb, 24, 8);
proto_tree_add_bytes_format(ntp_tree, hf_ntp_org, tvb, 24, 8,
org,
"Originate Time Stamp: %s",
ntp_fmt_ts(org, buff));
/* Receive Timestamp: This is the time at which the request arrived at
* the server.
*/
rec = tvb_get_ptr(tvb, 32, 8);
proto_tree_add_bytes_format(ntp_tree, hf_ntp_rec, tvb, 32, 8,
rec,
"Receive Time Stamp: %s",
ntp_fmt_ts(rec, buff));
/* Transmit Timestamp: This is the time at which the reply departed the
* server for the client.
*/
xmt = tvb_get_ptr(tvb, 40, 8);
proto_tree_add_bytes_format(ntp_tree, hf_ntp_xmt, tvb, 40, 8,
xmt,
"Transmit Time Stamp: %s",
ntp_fmt_ts(xmt, buff));
/* When the NTP authentication scheme is implemented, the
* Key Identifier and Message Digest fields contain the
* message authentication code (MAC) information defined in
* Appendix C of RFC-1305. Will print this as hex code for now.
*/
if ( tvb_reported_length_remaining(tvb, 48) >= 4 )
proto_tree_add_item(ntp_tree, hf_ntp_keyid, tvb, 48, 4,
FALSE);
if ( tvb_reported_length_remaining(tvb, 52) > 0 )
proto_tree_add_item(ntp_tree, hf_ntp_mac, tvb, 52,
tvb_reported_length_remaining(tvb, 52),
FALSE);
}
}
void
proto_register_ntp(void)
{
static hf_register_info hf[] = {
{ &hf_ntp_flags, {
"Flags", "ntp.flags", FT_UINT8, BASE_HEX,
NULL, 0, "Flags (Leap/Version/Mode)", HFILL }},
{ &hf_ntp_flags_li, {
"Leap Indicator", "ntp.flags.li", FT_UINT8, BASE_DEC,
VALS(li_types), NTP_LI_MASK, "Leap Indicator", HFILL }},
{ &hf_ntp_flags_vn, {
"Version number", "ntp.flags.vn", FT_UINT8, BASE_DEC,
VALS(ver_nums), NTP_VN_MASK, "Version number", HFILL }},
{ &hf_ntp_flags_mode, {
"Mode", "ntp.flags.mode", FT_UINT8, BASE_DEC,
VALS(mode_types), NTP_MODE_MASK, "Mode", HFILL }},
{ &hf_ntp_stratum, {
"Peer Clock Stratum", "ntp.stratum", FT_UINT8, BASE_DEC,
NULL, 0, "Peer Clock Stratum", HFILL }},
{ &hf_ntp_ppoll, {
"Peer Polling Interval", "ntp.ppoll", FT_UINT8, BASE_DEC,
NULL, 0, "Peer Polling Interval", HFILL }},
{ &hf_ntp_precision, {
"Peer Clock Precision", "ntp.precision", FT_UINT8, BASE_DEC,
NULL, 0, "Peer Clock Precision", HFILL }},
{ &hf_ntp_rootdelay, {
"Root Delay", "ntp.rootdelay", FT_DOUBLE, BASE_DEC,
NULL, 0, "Root Delay", HFILL }},
{ &hf_ntp_rootdispersion, {
"Clock Dispersion", "ntp.rootdispersion", FT_DOUBLE, BASE_DEC,
NULL, 0, "Clock Dispersion", HFILL }},
{ &hf_ntp_refid, {
"Reference Clock ID", "ntp.refid", FT_BYTES, BASE_NONE,
NULL, 0, "Reference Clock ID", HFILL }},
{ &hf_ntp_reftime, {
"Reference Clock Update Time", "ntp.reftime", FT_BYTES, BASE_NONE,
NULL, 0, "Reference Clock Update Time", HFILL }},
{ &hf_ntp_org, {
"Originate Time Stamp", "ntp.org", FT_BYTES, BASE_NONE,
NULL, 0, "Originate Time Stamp", HFILL }},
{ &hf_ntp_rec, {
"Receive Time Stamp", "ntp.rec", FT_BYTES, BASE_NONE,
NULL, 0, "Receive Time Stamp", HFILL }},
{ &hf_ntp_xmt, {
"Transmit Time Stamp", "ntp.xmt", FT_BYTES, BASE_NONE,
NULL, 0, "Transmit Time Stamp", HFILL }},
{ &hf_ntp_keyid, {
"Key ID", "ntp.keyid", FT_BYTES, BASE_HEX,
NULL, 0, "Key ID", HFILL }},
{ &hf_ntp_mac, {
"Message Authentication Code", "ntp.mac", FT_BYTES, BASE_HEX,
NULL, 0, "Message Authentication Code", HFILL }},
};
static gint *ett[] = {
&ett_ntp,
&ett_ntp_flags,
};
proto_ntp = proto_register_protocol("Network Time Protocol", "NTP",
"ntp");
proto_register_field_array(proto_ntp, hf, array_length(hf));
proto_register_subtree_array(ett, array_length(ett));
}
void
proto_reg_handoff_ntp(void)
{
dissector_handle_t ntp_handle;
ntp_handle = create_dissector_handle(dissect_ntp, proto_ntp);
dissector_add("udp.port", UDP_PORT_NTP, ntp_handle);
dissector_add("tcp.port", TCP_PORT_NTP, ntp_handle);
}
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