usr.sbin/timed/timed/measure.c

   1 /*-
   2  * Copyright (c) 1985, 1993
   3  *      The Regents of the University of California.  All rights reserved.
   4  *
   5  * Redistribution and use in source and binary forms, with or without
   6  * modification, are permitted provided that the following conditions
   7  * are met:
   8  * 1. Redistributions of source code must retain the above copyright
   9  *    notice, this list of conditions and the following disclaimer.
  10  * 2. Redistributions in binary form must reproduce the above copyright
  11  *    notice, this list of conditions and the following disclaimer in the
  12  *    documentation and/or other materials provided with the distribution.
  13  * 3. All advertising materials mentioning features or use of this software
  14  *    must display the following acknowledgement:
  15  *      This product includes software developed by the University of
  16  *      California, Berkeley and its contributors.
  17  * 4. Neither the name of the University nor the names of its contributors
  18  *    may be used to endorse or promote products derived from this software
  19  *    without specific prior written permission.
  20  *
  21  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  22  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  23  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  24  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  25  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  26  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  27  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  28  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  29  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  30  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  31  * SUCH DAMAGE.
  32  *
  33  * @(#)measure.c        8.1 (Berkeley) 6/6/93
  34  * $FreeBSD: src/usr.sbin/timed/timed/measure.c,v 1.6 1999/08/28 01:20:17 peter Exp $
  35  * $DragonFly: src/usr.sbin/timed/timed/measure.c,v 1.7 2004/09/05 02:20:15 dillon Exp $
  36  */
  37
  38 #include "globals.h"
  39 #include <netinet/in_systm.h>
  40 #include <netinet/ip.h>
  41 #include <netinet/ip_icmp.h>
  42
  43 #define MSEC_DAY        (SECDAY*1000)
  44
  45 #define PACKET_IN       1024
  46
  47 #define MSGS            5               /* timestamps to average */
  48 #define TRIALS          10              /* max # of timestamps sent */
  49
  50 extern int sock_raw;
  51
  52 int measure_delta;
  53
  54 static n_short seqno = 0;
  55
  56 /*
  57  * Measures the differences between machines' clocks using
  58  * ICMP timestamp messages.
  59  */
  60 int                                     /* status val defined in globals.h */
  61 measure(u_long maxmsec,                 /* wait this many msec at most */
  62         u_long wmsec,                   /* msec to wait for an answer */
  63         char *hname, struct sockaddr_in *addr,
  64         int printerr)                   /* print complaints on stderr */
  65 {
  66         int length;
  67         int measure_status;
  68         int rcvcount, trials;
  69         int cc, count;
  70         fd_set ready;
  71         long sendtime, recvtime, histime1, histime2;
  72         long idelta, odelta, total;
  73         long min_idelta, min_odelta;
  74         struct timeval tdone, tcur, ttrans, twait, tout;
  75         u_char packet[PACKET_IN], opacket[64];
  76         struct icmp *icp = (struct icmp *)packet;
  77         struct icmp *oicp = (struct icmp *)opacket;
  78         struct ip *ip = (struct ip *)packet;
  79
  80         min_idelta = min_odelta = 0x7fffffff;
  81         measure_status = HOSTDOWN;
  82         measure_delta = HOSTDOWN;
  83         errno = 0;
  84         trials = 0;     /* avoid compiler warning due to goto quit below */
  85
  86         /* open raw socket used to measure time differences */
  87         if (sock_raw < 0) {
  88                 sock_raw = socket(AF_INET, SOCK_RAW, IPPROTO_ICMP);
  89                 if (sock_raw < 0)  {
  90                         syslog(LOG_ERR, "opening raw socket: %m");
  91                         goto quit;
  92                 }
  93         }
  94
  95
  96         /*
  97          * empty the icmp input queue
  98          */
  99         FD_ZERO(&ready);
 100         for (;;) {
 101                 tout.tv_sec = tout.tv_usec = 0;
 102                 FD_SET(sock_raw, &ready);
 103                 if (select(sock_raw+1, &ready, 0,0, &tout)) {
 104                         length = sizeof(struct sockaddr_in);
 105                         cc = recvfrom(sock_raw, (char *)packet, PACKET_IN, 0,
 106                                       0,&length);
 107                         if (cc < 0)
 108                                 goto quit;
 109                         continue;
 110                 }
 111                 break;
 112         }
 113
 114         /*
 115          * Choose the smallest transmission time in each of the two
 116          * directions. Use these two latter quantities to compute the delta
 117          * between the two clocks.
 118          */
 119
 120         oicp->icmp_type = ICMP_TSTAMP;
 121         oicp->icmp_code = 0;
 122         oicp->icmp_id = getpid();
 123         oicp->icmp_rtime = 0;
 124         oicp->icmp_ttime = 0;
 125         oicp->icmp_seq = seqno;
 126
 127         FD_ZERO(&ready);
 128
 129         gettimeofday(&tdone, 0);
 130         mstotvround(&tout, maxmsec);
 131         timevaladd(&tdone, &tout);              /* when we give up */
 132
 133         mstotvround(&twait, wmsec);
 134
 135         rcvcount = 0;
 136         trials = 0;
 137         while (rcvcount < MSGS) {
 138                 gettimeofday(&tcur, 0);
 139
 140                 /*
 141                  * keep sending until we have sent the max
 142                  */
 143                 if (trials < TRIALS) {
 144                         trials++;
 145                         oicp->icmp_otime = htonl((tcur.tv_sec % SECDAY) * 1000
 146                                                  + tcur.tv_usec / 1000);
 147                         oicp->icmp_cksum = 0;
 148                         oicp->icmp_cksum = in_cksum((u_short*)oicp,
 149                                                     sizeof(*oicp));
 150
 151                         count = sendto(sock_raw, opacket, sizeof(*oicp), 0,
 152                                        (struct sockaddr*)addr,
 153                                        sizeof(struct sockaddr));
 154                         if (count < 0) {
 155                                 if (measure_status == HOSTDOWN)
 156                                         measure_status = UNREACHABLE;
 157                                 goto quit;
 158                         }
 159                         ++oicp->icmp_seq;
 160
 161                         ttrans = tcur;
 162                         timevaladd(&ttrans, &twait);
 163                 } else {
 164                         ttrans = tdone;
 165                 }
 166
 167                 while (rcvcount < trials) {
 168                         timevalsub(&tout, &ttrans, &tcur);
 169                         if (tout.tv_sec < 0)
 170                                 tout.tv_sec = 0;
 171
 172                         FD_SET(sock_raw, &ready);
 173                         count = select(sock_raw+1, &ready, NULL, NULL, &tout);
 174                         gettimeofday(&tcur, NULL);
 175                         if (count <= 0)
 176                                 break;
 177
 178                         length = sizeof(struct sockaddr_in);
 179                         cc = recvfrom(sock_raw, (char *)packet, PACKET_IN, 0,
 180                                       0,&length);
 181                         if (cc < 0)
 182                                 goto quit;
 183
 184                         /*
 185                          * got something.  See if it is ours
 186                          */
 187                         icp = (struct icmp *)(packet + (ip->ip_hl << 2));
 188                         if (cc < (int)sizeof(*ip)
 189                             || icp->icmp_type != ICMP_TSTAMPREPLY
 190                             || icp->icmp_id != oicp->icmp_id
 191                             || icp->icmp_seq < seqno
 192                             || icp->icmp_seq >= oicp->icmp_seq)
 193                                 continue;
 194
 195
 196                         sendtime = ntohl(icp->icmp_otime);
 197                         recvtime = ((tcur.tv_sec % SECDAY) * 1000 +
 198                                     tcur.tv_usec / 1000);
 199
 200                         total = recvtime-sendtime;
 201                         if (total < 0)  /* do not hassle midnight */
 202                                 continue;
 203
 204                         rcvcount++;
 205                         histime1 = ntohl(icp->icmp_rtime);
 206                         histime2 = ntohl(icp->icmp_ttime);
 207                         /*
 208                          * a host using a time format different from
 209                          * msec. since midnight UT (as per RFC792) should
 210                          * set the high order bit of the 32-bit time
 211                          * value it transmits.
 212                          */
 213                         if ((histime1 & 0x80000000) != 0) {
 214                                 measure_status = NONSTDTIME;
 215                                 goto quit;
 216                         }
 217                         measure_status = GOOD;
 218
 219                         idelta = recvtime-histime2;
 220                         odelta = histime1-sendtime;
 221
 222                         /* do not be confused by midnight */
 223                         if (idelta < -MSEC_DAY/2) idelta += MSEC_DAY;
 224                         else if (idelta > MSEC_DAY/2) idelta -= MSEC_DAY;
 225
 226                         if (odelta < -MSEC_DAY/2) odelta += MSEC_DAY;
 227                         else if (odelta > MSEC_DAY/2) odelta -= MSEC_DAY;
 228
 229                         /* save the quantization error so that we can get a
 230                          * measurement finer than our system clock.
 231                          */
 232                         if (total < MIN_ROUND) {
 233                                 measure_delta = (odelta - idelta)/2;
 234                                 goto quit;
 235                         }
 236
 237                         if (idelta < min_idelta)
 238                                 min_idelta = idelta;
 239                         if (odelta < min_odelta)
 240                                 min_odelta = odelta;
 241
 242                         measure_delta = (min_odelta - min_idelta)/2;
 243                 }
 244
 245                 if (tcur.tv_sec > tdone.tv_sec
 246                     || (tcur.tv_sec == tdone.tv_sec
 247                         && tcur.tv_usec >= tdone.tv_usec))
 248                         break;
 249         }
 250
 251 quit:
 252         seqno += TRIALS;                /* allocate our sequence numbers */
 253
 254         /*
 255          * If no answer is received for TRIALS consecutive times,
 256          * the machine is assumed to be down
 257          */
 258         if (measure_status == GOOD) {
 259                 if (trace) {
 260                         fprintf(fd,
 261                                 "measured delta %4d, %d trials to %-15s %s\n",
 262                                 measure_delta, trials,
 263                                 inet_ntoa(addr->sin_addr), hname);
 264                 }
 265         } else if (printerr) {
 266                 if (errno != 0)
 267                         warn("measure %s", hname);
 268         } else {
 269                 if (errno != 0) {
 270                         syslog(LOG_ERR, "measure %s: %m", hname);
 271                 } else {
 272                         syslog(LOG_ERR, "measure: %s did not respond", hname);
 273                 }
 274                 if (trace) {
 275                         fprintf(fd,
 276                                 "measure: %s failed after %d trials\n",
 277                                 hname, trials);
 278                         fflush(fd);
 279                 }
 280         }
 281
 282         return(measure_status);
 283 }
 284
 285
 286
 287
 288
 289 /*
 290  * round a number of milliseconds into a struct timeval
 291  */
 292 void
 293 mstotvround(struct timeval *res, long x)
 294 {
 295
 296         if (x < 0)
 297                 x = -((-x + 3)/5);
 298         else
 299                 x = (x+3)/5;
 300         x *= 5;
 301
 302         res->tv_sec = x/1000;
 303         res->tv_usec = (x-res->tv_sec*1000)*1000;
 304         if (res->tv_usec < 0) {
 305                 res->tv_usec += 1000000;
 306                 res->tv_sec--;
 307         }
 308 }
 309
 310 void
 311 timevaladd(struct timeval *tv1, struct timeval *tv2)
 312 {
 313
 314         tv1->tv_sec += tv2->tv_sec;
 315         tv1->tv_usec += tv2->tv_usec;
 316         if (tv1->tv_usec >= 1000000) {
 317                 tv1->tv_sec++;
 318                 tv1->tv_usec -= 1000000;
 319         }
 320         if (tv1->tv_usec < 0) {
 321                 tv1->tv_sec--;
 322                 tv1->tv_usec += 1000000;
 323         }
 324 }
 325
 326 void
 327 timevalsub(struct timeval *res, struct timeval *tv1, struct timeval *tv2)
 328 {
 329
 330         res->tv_sec = tv1->tv_sec - tv2->tv_sec;
 331         res->tv_usec = tv1->tv_usec - tv2->tv_usec;
 332         if (res->tv_usec >= 1000000) {
 333                 res->tv_sec++;
 334                 res->tv_usec -= 1000000;
 335         }
 336         if (res->tv_usec < 0) {
 337                 res->tv_sec--;
 338                 res->tv_usec += 1000000;
 339         }
 340 }