timed.tproj/timed.tproj/measure.c

   1 /*
   2  * Copyright (c) 1999 Apple Computer, Inc. All rights reserved.
   3  *
   4  * @APPLE_LICENSE_HEADER_START@
   5  *
   6  * "Portions Copyright (c) 1999 Apple Computer, Inc.  All Rights
   7  * Reserved.  This file contains Original Code and/or Modifications of
   8  * Original Code as defined in and that are subject to the Apple Public
   9  * Source License Version 1.0 (the 'License').  You may not use this file
  10  * except in compliance with the License.  Please obtain a copy of the
  11  * License at http://www.apple.com/publicsource and read it before using
  12  * this file.
  13  *
  14  * The Original Code and all software distributed under the License are
  15  * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
  16  * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
  17  * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
  18  * FITNESS FOR A PARTICULAR PURPOSE OR NON-INFRINGEMENT.  Please see the
  19  * License for the specific language governing rights and limitations
  20  * under the License."
  21  *
  22  * @APPLE_LICENSE_HEADER_END@
  23  */
  24 /*-
  25  * Copyright (c) 1985, 1993
  26  *      The Regents of the University of California.  All rights reserved.
  27  *
  28  * Redistribution and use in source and binary forms, with or without
  29  * modification, are permitted provided that the following conditions
  30  * are met:
  31  * 1. Redistributions of source code must retain the above copyright
  32  *    notice, this list of conditions and the following disclaimer.
  33  * 2. Redistributions in binary form must reproduce the above copyright
  34  *    notice, this list of conditions and the following disclaimer in the
  35  *    documentation and/or other materials provided with the distribution.
  36  * 3. All advertising materials mentioning features or use of this software
  37  *    must display the following acknowledgement:
  38  *      This product includes software developed by the University of
  39  *      California, Berkeley and its contributors.
  40  * 4. Neither the name of the University nor the names of its contributors
  41  *    may be used to endorse or promote products derived from this software
  42  *    without specific prior written permission.
  43  *
  44  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  45  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  46  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  47  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  48  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  49  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  50  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  51  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  52  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  53  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  54  * SUCH DAMAGE.
  55  */
  56
  57 #ifndef lint
  58 static char sccsid[] = "@(#)measure.c   8.2 (Berkeley) 3/26/95";
  59 #endif /* not lint */
  60
  61 #ifdef sgi
  62 #ident "$Revision: 1.1.1.1 $"
  63 #endif
  64
  65 #include "globals.h"
  66 #include <netinet/in_systm.h>
  67 #include <netinet/ip.h>
  68 #include <netinet/ip_icmp.h>
  69
  70 #define MSEC_DAY        (SECDAY*1000)
  71
  72 #define PACKET_IN       1024
  73
  74 #define MSGS            5               /* timestamps to average */
  75 #define TRIALS          10              /* max # of timestamps sent */
  76
  77 extern int sock_raw;
  78
  79 int measure_delta;
  80
  81 static n_short seqno = 0;
  82
  83 /*
  84  * Measures the differences between machines' clocks using
  85  * ICMP timestamp messages.
  86  */
  87 int                                     /* status val defined in globals.h */
  88 measure(maxmsec, wmsec, hname, addr, print)
  89         u_long maxmsec;                 /* wait this many msec at most */
  90         u_long wmsec;                   /* msec to wait for an answer */
  91         char *hname;
  92         struct sockaddr_in *addr;
  93         int print;                      /* print complaints on stderr */
  94 {
  95         int length;
  96         int measure_status;
  97         int rcvcount, trials;
  98         int cc, count;
  99         fd_set ready;
 100         long sendtime, recvtime, histime1, histime2;
 101         long idelta, odelta, total;
 102         long min_idelta, min_odelta;
 103         struct timeval tdone, tcur, ttrans, twait, tout;
 104         u_char packet[PACKET_IN], opacket[64];
 105         register struct icmp *icp = (struct icmp *) packet;
 106         register struct icmp *oicp = (struct icmp *) opacket;
 107         struct ip *ip = (struct ip *) packet;
 108
 109         min_idelta = min_odelta = 0x7fffffff;
 110         measure_status = HOSTDOWN;
 111         measure_delta = HOSTDOWN;
 112         errno = 0;
 113
 114         /* open raw socket used to measure time differences */
 115         if (sock_raw < 0) {
 116                 sock_raw = socket(AF_INET, SOCK_RAW, IPPROTO_ICMP);
 117                 if (sock_raw < 0)  {
 118                         syslog(LOG_ERR, "opening raw socket: %m");
 119                         goto quit;
 120                 }
 121         }
 122
 123
 124         /*
 125          * empty the icmp input queue
 126          */
 127         FD_ZERO(&ready);
 128         for (;;) {
 129                 tout.tv_sec = tout.tv_usec = 0;
 130                 FD_SET(sock_raw, &ready);
 131                 if (select(sock_raw+1, &ready, 0,0, &tout)) {
 132                         length = sizeof(struct sockaddr_in);
 133                         cc = recvfrom(sock_raw, (char *)packet, PACKET_IN, 0,
 134                                       0,&length);
 135                         if (cc < 0)
 136                                 goto quit;
 137                         continue;
 138                 }
 139                 break;
 140         }
 141
 142         /*
 143          * Choose the smallest transmission time in each of the two
 144          * directions. Use these two latter quantities to compute the delta
 145          * between the two clocks.
 146          */
 147
 148         oicp->icmp_type = ICMP_TSTAMP;
 149         oicp->icmp_code = 0;
 150         oicp->icmp_id = getpid();
 151         oicp->icmp_rtime = 0;
 152         oicp->icmp_ttime = 0;
 153         oicp->icmp_seq = seqno;
 154
 155         FD_ZERO(&ready);
 156
 157 #ifdef sgi
 158         sginap(1);                      /* start at a clock tick */
 159 #endif /* sgi */
 160
 161         (void)gettimeofday(&tdone, 0);
 162         mstotvround(&tout, maxmsec);
 163         timevaladd(&tdone, &tout);              /* when we give up */
 164
 165         mstotvround(&twait, wmsec);
 166
 167         rcvcount = 0;
 168         trials = 0;
 169         while (rcvcount < MSGS) {
 170                 (void)gettimeofday(&tcur, 0);
 171
 172                 /*
 173                  * keep sending until we have sent the max
 174                  */
 175                 if (trials < TRIALS) {
 176                         trials++;
 177                         oicp->icmp_otime = htonl((tcur.tv_sec % SECDAY) * 1000
 178                                                  + tcur.tv_usec / 1000);
 179                         oicp->icmp_cksum = 0;
 180                         oicp->icmp_cksum = in_cksum((u_short*)oicp,
 181                                                     sizeof(*oicp));
 182
 183                         count = sendto(sock_raw, opacket, sizeof(*oicp), 0,
 184                                        (struct sockaddr*)addr,
 185                                        sizeof(struct sockaddr));
 186                         if (count < 0) {
 187                                 if (measure_status == HOSTDOWN)
 188                                         measure_status = UNREACHABLE;
 189                                 goto quit;
 190                         }
 191                         ++oicp->icmp_seq;
 192
 193                         ttrans = tcur;
 194                         timevaladd(&ttrans, &twait);
 195                 } else {
 196                         ttrans = tdone;
 197                 }
 198
 199                 while (rcvcount < trials) {
 200                         timevalsub(&tout, &ttrans, &tcur);
 201                         if (tout.tv_sec < 0)
 202                                 tout.tv_sec = 0;
 203
 204                         FD_SET(sock_raw, &ready);
 205                         count = select(sock_raw+1, &ready, (fd_set *)0,
 206                                        (fd_set *)0, &tout);
 207                         (void)gettimeofday(&tcur, (struct timezone *)0);
 208                         if (count <= 0)
 209                                 break;
 210
 211                         length = sizeof(struct sockaddr_in);
 212                         cc = recvfrom(sock_raw, (char *)packet, PACKET_IN, 0,
 213                                       0,&length);
 214                         if (cc < 0)
 215                                 goto quit;
 216
 217                         /*
 218                          * got something.  See if it is ours
 219                          */
 220                         icp = (struct icmp *)(packet + (ip->ip_hl << 2));
 221                         if (cc < sizeof(*ip)
 222                             || icp->icmp_type != ICMP_TSTAMPREPLY
 223                             || icp->icmp_id != oicp->icmp_id
 224                             || icp->icmp_seq < seqno
 225                             || icp->icmp_seq >= oicp->icmp_seq)
 226                                 continue;
 227
 228
 229                         sendtime = ntohl(icp->icmp_otime);
 230                         recvtime = ((tcur.tv_sec % SECDAY) * 1000 +
 231                                     tcur.tv_usec / 1000);
 232
 233                         total = recvtime-sendtime;
 234                         if (total < 0)  /* do not hassle midnight */
 235                                 continue;
 236
 237                         rcvcount++;
 238                         histime1 = ntohl(icp->icmp_rtime);
 239                         histime2 = ntohl(icp->icmp_ttime);
 240                         /*
 241                          * a host using a time format different from
 242                          * msec. since midnight UT (as per RFC792) should
 243                          * set the high order bit of the 32-bit time
 244                          * value it transmits.
 245                          */
 246                         if ((histime1 & 0x80000000) != 0) {
 247                                 measure_status = NONSTDTIME;
 248                                 goto quit;
 249                         }
 250                         measure_status = GOOD;
 251
 252                         idelta = recvtime-histime2;
 253                         odelta = histime1-sendtime;
 254
 255                         /* do not be confused by midnight */
 256                         if (idelta < -MSEC_DAY/2) idelta += MSEC_DAY;
 257                         else if (idelta > MSEC_DAY/2) idelta -= MSEC_DAY;
 258
 259                         if (odelta < -MSEC_DAY/2) odelta += MSEC_DAY;
 260                         else if (odelta > MSEC_DAY/2) odelta -= MSEC_DAY;
 261
 262                         /* save the quantization error so that we can get a
 263                          * measurement finer than our system clock.
 264                          */
 265                         if (total < MIN_ROUND) {
 266                                 measure_delta = (odelta - idelta)/2;
 267                                 goto quit;
 268                         }
 269
 270                         if (idelta < min_idelta)
 271                                 min_idelta = idelta;
 272                         if (odelta < min_odelta)
 273                                 min_odelta = odelta;
 274
 275                         measure_delta = (min_odelta - min_idelta)/2;
 276                 }
 277
 278                 if (tcur.tv_sec > tdone.tv_sec
 279                     || (tcur.tv_sec == tdone.tv_sec
 280                         && tcur.tv_usec >= tdone.tv_usec))
 281                         break;
 282         }
 283
 284 quit:
 285         seqno += TRIALS;                /* allocate our sequence numbers */
 286
 287         /*
 288          * If no answer is received for TRIALS consecutive times,
 289          * the machine is assumed to be down
 290          */
 291         if (measure_status == GOOD) {
 292                 if (trace) {
 293                         fprintf(fd,
 294                                 "measured delta %4d, %d trials to %-15s %s\n",
 295                                 measure_delta, trials,
 296                                 inet_ntoa(addr->sin_addr), hname);
 297                 }
 298         } else if (print) {
 299                 if (errno != 0)
 300                         fprintf(stderr, "measure %s: %s\n", hname,
 301                                 strerror(errno));
 302         } else {
 303                 if (errno != 0) {
 304                         syslog(LOG_ERR, "measure %s: %m", hname);
 305                 } else {
 306                         syslog(LOG_ERR, "measure: %s did not respond", hname);
 307                 }
 308                 if (trace) {
 309                         fprintf(fd,
 310                                 "measure: %s failed after %d trials\n",
 311                                 hname, trials);
 312                         (void)fflush(fd);
 313                 }
 314         }
 315
 316         return(measure_status);
 317 }
 318
 319
 320
 321
 322
 323 /*
 324  * round a number of milliseconds into a struct timeval
 325  */
 326 void
 327 mstotvround(res, x)
 328         struct timeval *res;
 329         long x;
 330 {
 331 #ifndef sgi
 332         if (x < 0)
 333                 x = -((-x + 3)/5);
 334         else
 335                 x = (x+3)/5;
 336         x *= 5;
 337 #endif /* sgi */
 338         res->tv_sec = x/1000;
 339         res->tv_usec = (x-res->tv_sec*1000)*1000;
 340         if (res->tv_usec < 0) {
 341                 res->tv_usec += 1000000;
 342                 res->tv_sec--;
 343         }
 344 }
 345
 346 void
 347 timevaladd(tv1, tv2)
 348         struct timeval *tv1, *tv2;
 349 {
 350         tv1->tv_sec += tv2->tv_sec;
 351         tv1->tv_usec += tv2->tv_usec;
 352         if (tv1->tv_usec >= 1000000) {
 353                 tv1->tv_sec++;
 354                 tv1->tv_usec -= 1000000;
 355         }
 356         if (tv1->tv_usec < 0) {
 357                 tv1->tv_sec--;
 358                 tv1->tv_usec += 1000000;
 359         }
 360 }
 361
 362 void
 363 timevalsub(res, tv1, tv2)
 364         struct timeval *res, *tv1, *tv2;
 365 {
 366         res->tv_sec = tv1->tv_sec - tv2->tv_sec;
 367         res->tv_usec = tv1->tv_usec - tv2->tv_usec;
 368         if (res->tv_usec >= 1000000) {
 369                 res->tv_sec++;
 370                 res->tv_usec -= 1000000;
 371         }
 372         if (res->tv_usec < 0) {
 373                 res->tv_sec--;
 374                 res->tv_usec += 1000000;
 375         }
 376 }