001 package railo.runtime.net.ntp; 002 003 import java.text.DecimalFormat; 004 import java.util.Date; 005 006 import railo.commons.i18n.DateFormatPool; 007 008 public final class NtpMessage 009 { 010 /** 011 * This is a two-bit code warning of an impending leap second to be 012 * inserted/deleted in the last minute of the current day. It's values 013 * may be as follows: 014 * 015 * Value Meaning 016 * ----- ------- 017 * 0 no warning 018 * 1 last minute has 61 seconds 019 * 2 last minute has 59 seconds) 020 * 3 alarm condition (clock not synchronized) 021 */ 022 public byte leapIndicator = 0; 023 024 025 /** 026 * This value indicates the NTP/SNTP version number. The version number 027 * is 3 for Version 3 (IPv4 only) and 4 for Version 4 (IPv4, IPv6 and OSI). 028 * If necessary to distinguish between IPv4, IPv6 and OSI, the 029 * encapsulating context must be inspected. 030 */ 031 public byte version = 3; 032 033 034 /** 035 * This value indicates the mode, with values defined as follows: 036 * 037 * Mode Meaning 038 * ---- ------- 039 * 0 reserved 040 * 1 symmetric active 041 * 2 symmetric passive 042 * 3 client 043 * 4 server 044 * 5 broadcast 045 * 6 reserved for NTP control message 046 * 7 reserved for private use 047 * 048 * In unicast and anycast modes, the client sets this field to 3 (client) 049 * in the request and the server sets it to 4 (server) in the reply. In 050 * multicast mode, the server sets this field to 5 (broadcast). 051 */ 052 public byte mode = 0; 053 054 055 /** 056 * This value indicates the stratum level of the local clock, with values 057 * defined as follows: 058 * 059 * Stratum Meaning 060 * ---------------------------------------------- 061 * 0 unspecified or unavailable 062 * 1 primary reference (e.g., radio clock) 063 * 2-15 secondary reference (via NTP or SNTP) 064 * 16-255 reserved 065 */ 066 public short stratum = 0; 067 068 069 /** 070 * This value indicates the maximum interval between successive messages, 071 * in seconds to the nearest power of two. The values that can appear in 072 * this field presently range from 4 (16 s) to 14 (16284 s); however, most 073 * applications use only the sub-range 6 (64 s) to 10 (1024 s). 074 */ 075 public byte pollInterval = 0; 076 077 078 /** 079 * This value indicates the precision of the local clock, in seconds to 080 * the nearest power of two. The values that normally appear in this field\ 081 * range from -6 for mains-frequency clocks to -20 for microsecond clocks 082 * found in some workstations. 083 */ 084 public byte precision = 0; 085 086 087 /** 088 * This value indicates the total roundtrip delay to the primary reference 089 * source, in seconds. Note that this variable can take on both positive 090 * and negative values, depending on the relative time and frequency 091 * offsets. The values that normally appear in this field range from 092 * negative values of a few milliseconds to positive values of several 093 * hundred milliseconds. 094 */ 095 public double rootDelay = 0; 096 097 098 /** 099 * This value indicates the nominal error relative to the primary reference 100 * source, in seconds. The values that normally appear in this field 101 * range from 0 to several hundred milliseconds. 102 */ 103 public double rootDispersion = 0; 104 105 106 /** 107 * This is a 4-byte array identifying the particular reference source. 108 * In the case of NTP Version 3 or Version 4 stratum-0 (unspecified) or 109 * stratum-1 (primary) servers, this is a four-character ASCII string, left 110 * justified and zero padded to 32 bits. In NTP Version 3 secondary 111 * servers, this is the 32-bit IPv4 address of the reference source. In NTP 112 * Version 4 secondary servers, this is the low order 32 bits of the latest 113 * transmit timestamp of the reference source. NTP primary (stratum 1) 114 * servers should set this field to a code identifying the external 115 * reference source according to the following list. If the external 116 * reference is one of those listed, the associated code should be used. 117 * Codes for sources not listed can be contrived as appropriate. 118 * 119 * Code External Reference Source 120 * ---- ------------------------- 121 * LOCL uncalibrated local clock used as a primary reference for 122 * a subnet without external means of synchronization 123 * PPS atomic clock or other pulse-per-second source 124 * individually calibrated to national standards 125 * ACTS NIST dialup modem service 126 * USNO USNO modem service 127 * PTB PTB (Germany) modem service 128 * TDF Allouis (France) Radio 164 kHz 129 * DCF Mainflingen (Germany) Radio 77.5 kHz 130 * MSF Rugby (UK) Radio 60 kHz 131 * WWV Ft. Collins (US) Radio 2.5, 5, 10, 15, 20 MHz 132 * WWVB Boulder (US) Radio 60 kHz 133 * WWVH Kaui Hawaii (US) Radio 2.5, 5, 10, 15 MHz 134 * CHU Ottawa (Canada) Radio 3330, 7335, 14670 kHz 135 * LORC LORAN-C radionavigation system 136 * OMEG OMEGA radionavigation system 137 * GPS Global Positioning Service 138 * GOES Geostationary Orbit Environment Satellite 139 */ 140 public byte[] referenceIdentifier = {0, 0, 0, 0}; 141 142 143 /** 144 * This is the time at which the local clock was last set or corrected, in 145 * seconds since 00:00 1-Jan-1900. 146 */ 147 public double referenceTimestamp = 0; 148 149 150 /** 151 * This is the time at which the request departed the client for the 152 * server, in seconds since 00:00 1-Jan-1900. 153 */ 154 public double originateTimestamp = 0; 155 156 157 /** 158 * This is the time at which the request arrived at the server, in seconds 159 * since 00:00 1-Jan-1900. 160 */ 161 public double receiveTimestamp = 0; 162 163 164 /** 165 * This is the time at which the reply departed the server for the client, 166 * in seconds since 00:00 1-Jan-1900. 167 */ 168 public double transmitTimestamp = 0; 169 170 171 172 /** 173 * Constructs a new NtpMessage from an array of bytes. 174 * @param array 175 */ 176 public NtpMessage(byte[] array) 177 { 178 // See the packet format diagram in RFC 2030 for details 179 leapIndicator = (byte) ((array[0] >> 6) & 0x3); 180 version = (byte) ((array[0] >> 3) & 0x7); 181 mode = (byte) (array[0] & 0x7); 182 stratum = unsignedByteToShort(array[1]); 183 pollInterval = array[2]; 184 precision = array[3]; 185 186 rootDelay = (array[4] * 256.0) + 187 unsignedByteToShort(array[5]) + 188 (unsignedByteToShort(array[6]) / 256.0) + 189 (unsignedByteToShort(array[7]) / 65536.0); 190 191 rootDispersion = (unsignedByteToShort(array[8]) * 256.0) + 192 unsignedByteToShort(array[9]) + 193 (unsignedByteToShort(array[10]) / 256.0) + 194 (unsignedByteToShort(array[11]) / 65536.0); 195 196 referenceIdentifier[0] = array[12]; 197 referenceIdentifier[1] = array[13]; 198 referenceIdentifier[2] = array[14]; 199 referenceIdentifier[3] = array[15]; 200 201 referenceTimestamp = decodeTimestamp(array, 16); 202 originateTimestamp = decodeTimestamp(array, 24); 203 receiveTimestamp = decodeTimestamp(array, 32); 204 transmitTimestamp = decodeTimestamp(array, 40); 205 } 206 207 208 209 /** 210 * Constructs a new NtpMessage 211 * @param leapIndicator 212 * @param version 213 * @param mode 214 * @param stratum 215 * @param pollInterval 216 * @param precision 217 * @param rootDelay 218 * @param rootDispersion 219 * @param referenceIdentifier 220 * @param referenceTimestamp 221 * @param originateTimestamp 222 * @param receiveTimestamp 223 * @param transmitTimestamp 224 */ 225 public NtpMessage(byte leapIndicator, 226 byte version, 227 byte mode, 228 short stratum, 229 byte pollInterval, 230 byte precision, 231 double rootDelay, 232 double rootDispersion, 233 byte[] referenceIdentifier, 234 double referenceTimestamp, 235 double originateTimestamp, 236 double receiveTimestamp, 237 double transmitTimestamp) 238 { 239 // ToDo: Validity checking 240 this.leapIndicator = leapIndicator; 241 this.version = version; 242 this.mode = mode; 243 this.stratum = stratum; 244 this.pollInterval = pollInterval; 245 this.precision = precision; 246 this.rootDelay = rootDelay; 247 this.rootDispersion = rootDispersion; 248 this.referenceIdentifier = referenceIdentifier; 249 this.referenceTimestamp = referenceTimestamp; 250 this.originateTimestamp = originateTimestamp; 251 this.receiveTimestamp = receiveTimestamp; 252 this.transmitTimestamp = transmitTimestamp; 253 } 254 255 256 257 /** 258 * Constructs a new NtpMessage in client -> server mode, and sets the 259 * transmit timestamp to the current time. 260 */ 261 public NtpMessage() 262 { 263 // Note that all the other member variables are already set with 264 // appropriate default values. 265 this.mode = 3; 266 this.transmitTimestamp = (System.currentTimeMillis()/1000.0) + 2208988800.0; 267 } 268 269 270 271 /** 272 * This method constructs the data bytes of a raw NTP packet. 273 * @return 274 */ 275 public byte[] toByteArray() 276 { 277 // All bytes are automatically set to 0 278 byte[] p = new byte[48]; 279 280 p[0] = (byte) (leapIndicator << 6 | version << 3 | mode); 281 p[1] = (byte) stratum; 282 p[2] = pollInterval; 283 p[3] = precision; 284 285 // root delay is a signed 16.16-bit FP, in Java an int is 32-bits 286 int l = (int) (rootDelay * 65536.0); 287 p[4] = (byte) ((l >> 24) & 0xFF); 288 p[5] = (byte) ((l >> 16) & 0xFF); 289 p[6] = (byte) ((l >> 8) & 0xFF); 290 p[7] = (byte) (l & 0xFF); 291 292 // root dispersion is an unsigned 16.16-bit FP, in Java there are no 293 // unsigned primitive types, so we use a long which is 64-bits 294 long ul = (long) (rootDispersion * 65536.0); 295 p[8] = (byte) ((ul >> 24) & 0xFF); 296 p[9] = (byte) ((ul >> 16) & 0xFF); 297 p[10] = (byte) ((ul >> 8) & 0xFF); 298 p[11] = (byte) (ul & 0xFF); 299 300 p[12] = referenceIdentifier[0]; 301 p[13] = referenceIdentifier[1]; 302 p[14] = referenceIdentifier[2]; 303 p[15] = referenceIdentifier[3]; 304 305 encodeTimestamp(p, 16, referenceTimestamp); 306 encodeTimestamp(p, 24, originateTimestamp); 307 encodeTimestamp(p, 32, receiveTimestamp); 308 encodeTimestamp(p, 40, transmitTimestamp); 309 310 return p; 311 } 312 313 314 315 /** 316 * Returns a string representation of a NtpMessage 317 * @return 318 */ 319 public String toString() 320 { 321 String precisionStr = new DecimalFormat("0.#E0").format(Math.pow(2, precision)); 322 return "Leap indicator: " + leapIndicator + "\n" + 323 "Version: " + version + "\n" + 324 "Mode: " + mode + "\n" + 325 "Stratum: " + stratum + "\n" + 326 "Poll: " + pollInterval + "\n" + 327 "Precision: " + precision + " (" + precisionStr + " seconds)\n" + 328 "Root delay: " + new DecimalFormat("0.00").format(rootDelay*1000) + " ms\n" + 329 "Root dispersion: " + new DecimalFormat("0.00").format(rootDispersion*1000) + " ms\n" + 330 "Reference identifier: " + referenceIdentifierToString(referenceIdentifier, stratum, version) + "\n" + 331 "Reference timestamp: " + timestampToString(referenceTimestamp) + "\n" + 332 "Originate timestamp: " + timestampToString(originateTimestamp) + "\n" + 333 "Receive timestamp: " + timestampToString(receiveTimestamp) + "\n" + 334 "Transmit timestamp: " + timestampToString(transmitTimestamp); 335 } 336 337 338 339 /** 340 * Converts an unsigned byte to a short. By default, Java assumes that 341 * a byte is signed. 342 * @param b 343 * @return 344 */ 345 public static short unsignedByteToShort(byte b) 346 { 347 if((b & 0x80)==0x80) return (short) (128 + (b & 0x7f)); 348 return b; 349 } 350 351 352 353 /** 354 * Will read 8 bytes of a message beginning at <code>pointer</code> 355 * and return it as a double, according to the NTP 64-bit timestamp 356 * format. 357 * @param array 358 * @param pointer 359 * @return 360 */ 361 public static double decodeTimestamp(byte[] array, int pointer) 362 { 363 double r = 0.0; 364 365 for(int i=0; i<8; i++) 366 { 367 r += unsignedByteToShort(array[pointer+i]) * Math.pow(2, (3-i)*8); 368 } 369 370 return r; 371 } 372 373 374 375 /** 376 * Encodes a timestamp in the specified position in the message 377 * @param array 378 * @param pointer 379 * @param timestamp 380 */ 381 public static void encodeTimestamp(byte[] array, int pointer, double timestamp) 382 { 383 // Converts a double into a 64-bit fixed point 384 for(int i=0; i<8; i++) 385 { 386 // 2^24, 2^16, 2^8, .. 2^-32 387 double base = Math.pow(2, (3-i)*8); 388 389 // Capture byte value 390 array[pointer+i] = (byte) (timestamp / base); 391 392 // Subtract captured value from remaining total 393 timestamp = timestamp - (unsignedByteToShort(array[pointer+i]) * base); 394 } 395 396 // From RFC 2030: It is advisable to fill the non-significan't 397 // low order bits of the timestamp with a random, unbiased 398 // bitstring, both to avoid systematic roundoff errors and as 399 // a means of loop detection and replay detection. 400 array[7] = (byte) (Math.random()*255.0); 401 } 402 403 404 405 /** 406 * Returns a timestamp (number of seconds since 00:00 1-Jan-1900) as a 407 * formatted date/time string. 408 * @param timestamp 409 * @return 410 */ 411 public static String timestampToString(double timestamp) 412 { 413 if(timestamp==0) return "0"; 414 415 // timestamp is relative to 1900, utc is used by Java and is relative 416 // to 1970 417 double utc = timestamp - (2208988800.0); 418 419 // milliseconds 420 long ms = (long) (utc * 1000.0); 421 422 // date/time 423 String date = DateFormatPool.format("dd-MMM-yyyy HH:mm:ss",new Date(ms)); 424 425 // fraction 426 double fraction = timestamp - ((long) timestamp); 427 String fractionSting = new DecimalFormat(".000000").format(fraction); 428 429 return date + fractionSting; 430 } 431 432 433 434 /** 435 * Returns a string representation of a reference identifier according 436 * to the rules set out in RFC 2030. 437 * @param ref 438 * @param stratum 439 * @param version 440 * @return 441 */ 442 public static String referenceIdentifierToString(byte[] ref, short stratum, byte version) 443 { 444 // From the RFC 2030: 445 // In the case of NTP Version 3 or Version 4 stratum-0 (unspecified) 446 // or stratum-1 (primary) servers, this is a four-character ASCII 447 // string, left justified and zero padded to 32 bits. 448 if(stratum==0 || stratum==1) 449 { 450 return new String(ref); 451 } 452 453 // In NTP Version 3 secondary servers, this is the 32-bit IPv4 454 // address of the reference source. 455 else if(version==3) 456 { 457 return unsignedByteToShort(ref[0]) + "." + 458 unsignedByteToShort(ref[1]) + "." + 459 unsignedByteToShort(ref[2]) + "." + 460 unsignedByteToShort(ref[3]); 461 } 462 463 // In NTP Version 4 secondary servers, this is the low order 32 bits 464 // of the latest transmit timestamp of the reference source. 465 else if(version==4) 466 { 467 return "" + ((unsignedByteToShort(ref[0]) / 256.0) + 468 (unsignedByteToShort(ref[1]) / 65536.0) + 469 (unsignedByteToShort(ref[2]) / 16777216.0) + 470 (unsignedByteToShort(ref[3]) / 4294967296.0)); 471 } 472 473 return ""; 474 } 475 }