Author: asomers
Date: Tue Aug 13 19:24:17 2019
New Revision: 350997
URL: https://svnweb.freebsd.org/changeset/base/350997

Log:
  ping6: use the monotonic clock to measure durations
  
  Submitted by: Ján Sučan <sucan...@gmail.com>
  MFC after:    2 weeks
  Sponsored by: Google, inc. (Google Summer of Code 2019)
  Differential Revision:        https://reviews.freebsd.org/D21226

Modified:
  head/sbin/ping6/ping6.c

Modified: head/sbin/ping6/ping6.c
==============================================================================
--- head/sbin/ping6/ping6.c     Tue Aug 13 19:23:45 2019        (r350996)
+++ head/sbin/ping6/ping6.c     Tue Aug 13 19:24:17 2019        (r350997)
@@ -107,7 +107,6 @@ __FBSDID("$FreeBSD$");
 #include <sys/capsicum.h>
 #include <sys/uio.h>
 #include <sys/socket.h>
-#include <sys/time.h>
 
 #include <net/if.h>
 #include <net/route.h>
@@ -133,6 +132,7 @@ __FBSDID("$FreeBSD$");
 #include <stdlib.h>
 #include <string.h>
 #include <sysexits.h>
+#include <time.h>
 #include <unistd.h>
 
 #ifdef IPSEC
@@ -144,7 +144,7 @@ __FBSDID("$FreeBSD$");
 
 struct tv32 {
        u_int32_t tv32_sec;
-       u_int32_t tv32_usec;
+       u_int32_t tv32_nsec;
 };
 
 #define MAXPACKETLEN   131072
@@ -288,7 +288,6 @@ static void  pr_rthdr(void *, size_t);
 static int      pr_bitrange(u_int32_t, int, int);
 static void     pr_retip(struct ip6_hdr *, u_char *);
 static void     summary(void);
-static void     tvsub(struct timeval *, struct timeval *);
 static int      setpolicy(int, char *);
 static char    *nigroup(char *, int);
 static void     usage(void);
@@ -296,7 +295,7 @@ static void  usage(void);
 int
 main(int argc, char *argv[])
 {
-       struct timeval last, intvl;
+       struct timespec last, intvl;
        struct sockaddr_in6 from, *sin6;
        struct addrinfo hints, *res;
        struct sigaction si_sa;
@@ -456,15 +455,15 @@ main(int argc, char *argv[])
                                errx(1, "%s: only root may use interval < 1s",
                                    strerror(EPERM));
                        }
-                       intvl.tv_sec = (long)t;
-                       intvl.tv_usec =
-                           (long)((t - intvl.tv_sec) * 1000000);
+                       intvl.tv_sec = (time_t)t;
+                       intvl.tv_nsec =
+                           (long)((t - intvl.tv_sec) * 1000000000);
                        if (intvl.tv_sec < 0)
                                errx(1, "illegal timing interval %s", optarg);
                        /* less than 1/hz does not make sense */
-                       if (intvl.tv_sec == 0 && intvl.tv_usec < 1) {
+                       if (intvl.tv_sec == 0 && intvl.tv_nsec < 1000) {
                                warnx("too small interval, raised to .000001");
-                               intvl.tv_usec = 1;
+                               intvl.tv_nsec = 1000;
                        }
                        options |= F_INTERVAL;
                        break;
@@ -1102,7 +1101,7 @@ main(int argc, char *argv[])
                while (preload--)
                        pinger();
        }
-       gettimeofday(&last, NULL);
+       clock_gettime(CLOCK_MONOTONIC, &last);
 
        sigemptyset(&si_sa.sa_mask);
        si_sa.sa_flags = 0;
@@ -1121,15 +1120,15 @@ main(int argc, char *argv[])
        }
        if (options & F_FLOOD) {
                intvl.tv_sec = 0;
-               intvl.tv_usec = 10000;
+               intvl.tv_nsec = 10000000;
        } else if ((options & F_INTERVAL) == 0) {
                intvl.tv_sec = interval / 1000;
-               intvl.tv_usec = interval % 1000 * 1000;
+               intvl.tv_nsec = interval % 1000 * 1000000;
        }
 
        almost_done = 0;
        while (seenint == 0) {
-               struct timeval now, timeout;
+               struct timespec now, timeout;
                struct msghdr m;
                struct iovec iov[2];
                fd_set rfds;
@@ -1147,21 +1146,13 @@ main(int argc, char *argv[])
 #endif
                FD_ZERO(&rfds);
                FD_SET(srecv, &rfds);
-               gettimeofday(&now, NULL);
-               timeout.tv_sec = last.tv_sec + intvl.tv_sec - now.tv_sec;
-               timeout.tv_usec = last.tv_usec + intvl.tv_usec - now.tv_usec;
-               while (timeout.tv_usec < 0) {
-                       timeout.tv_usec += 1000000;
-                       timeout.tv_sec--;
-               }
-               while (timeout.tv_usec > 1000000) {
-                       timeout.tv_usec -= 1000000;
-                       timeout.tv_sec++;
-               }
+               clock_gettime(CLOCK_MONOTONIC, &now);
+               timespecadd(&last, &intvl, &timeout);
+               timespecsub(&timeout, &now, &timeout);
                if (timeout.tv_sec < 0)
-                       timeout.tv_sec = timeout.tv_usec = 0;
+                       timespecclear(&timeout);
 
-               n = select(srecv + 1, &rfds, NULL, NULL, &timeout);
+               n = pselect(srecv + 1, &rfds, NULL, NULL, &timeout, NULL);
                if (n < 0)
                        continue;       /* EINTR */
                if (n == 1) {
@@ -1222,17 +1213,18 @@ main(int argc, char *argv[])
                         * if we've received any packets or (waittime)
                         * milliseconds if we haven't.
                         */
-                               intvl.tv_usec = 0;
+                               intvl.tv_nsec = 0;
                                if (nreceived) {
                                        intvl.tv_sec = 2 * tmax / 1000;
                                        if (intvl.tv_sec == 0)
                                                intvl.tv_sec = 1;
                                } else {
                                        intvl.tv_sec = waittime / 1000;
-                                       intvl.tv_usec = waittime % 1000 * 1000;
+                                       intvl.tv_nsec =
+                                               waittime % 1000 * 1000000;
                                }
                        }
-                       gettimeofday(&last, NULL);
+                       clock_gettime(CLOCK_MONOTONIC, &last);
                        if (ntransmitted - nreceived - 1 > nmissedmax) {
                                nmissedmax = ntransmitted - nreceived - 1;
                                if (options & F_MISSED)
@@ -1275,7 +1267,7 @@ onsignal(int sig)
  *     Compose and transmit an ICMP ECHO REQUEST packet.  The IP packet
  * will be added on by the kernel.  The ID field is our UNIX process ID,
  * and the sequence number is an ascending integer.  The first 8 bytes
- * of the data portion are used to hold a UNIX "timeval" struct in VAX
+ * of the data portion are used to hold a UNIX "timespec" struct in VAX
  * byte-order, to compute the round-trip time.
  */
 static size_t
@@ -1375,12 +1367,18 @@ pinger(void)
                icp->icmp6_id = htons(ident);
                icp->icmp6_seq = htons(seq);
                if (timing) {
-                       struct timeval tv;
+                       struct timespec tv;
                        struct tv32 *tv32;
-                       (void)gettimeofday(&tv, NULL);
+                       (void)clock_gettime(CLOCK_MONOTONIC, &tv);
                        tv32 = (struct tv32 *)&outpack[ICMP6ECHOLEN];
-                       tv32->tv32_sec = htonl(tv.tv_sec);
-                       tv32->tv32_usec = htonl(tv.tv_usec);
+                       /*
+                        * Truncate seconds down to 32 bits in order
+                        * to fit the timestamp within 8 bytes of the
+                        * packet. We're only concerned with
+                        * durations, not absolute times.
+                        */
+                       tv32->tv32_sec = (uint32_t)htonl(tv.tv_sec);
+                       tv32->tv32_nsec = (uint32_t)htonl(tv.tv_nsec);
                }
                cc = ICMP6ECHOLEN + datalen;
        }
@@ -1509,7 +1507,7 @@ pr_pack(u_char *buf, int cc, struct msghdr *mhdr)
        int fromlen;
        u_char *cp = NULL, *dp, *end = buf + cc;
        struct in6_pktinfo *pktinfo = NULL;
-       struct timeval tv, tp;
+       struct timespec tv, tp;
        struct tv32 *tpp;
        double triptime = 0;
        int dupflag;
@@ -1518,7 +1516,7 @@ pr_pack(u_char *buf, int cc, struct msghdr *mhdr)
        u_int16_t seq;
        char dnsname[MAXDNAME + 1];
 
-       (void)gettimeofday(&tv, NULL);
+       (void)clock_gettime(CLOCK_MONOTONIC, &tv);
 
        if (!mhdr || !mhdr->msg_name ||
            mhdr->msg_namelen != sizeof(struct sockaddr_in6) ||
@@ -1557,10 +1555,10 @@ pr_pack(u_char *buf, int cc, struct msghdr *mhdr)
                if (timing) {
                        tpp = (struct tv32 *)(icp + 1);
                        tp.tv_sec = ntohl(tpp->tv32_sec);
-                       tp.tv_usec = ntohl(tpp->tv32_usec);
-                       tvsub(&tv, &tp);
+                       tp.tv_nsec = ntohl(tpp->tv32_nsec);
+                       timespecsub(&tv, &tp, &tv);
                        triptime = ((double)tv.tv_sec) * 1000.0 +
-                           ((double)tv.tv_usec) / 1000.0;
+                           ((double)tv.tv_nsec) / 1000000.0;
                        tsum += triptime;
                        tsumsq += triptime * triptime;
                        if (triptime < tmin)
@@ -2206,21 +2204,6 @@ get_pathmtu(struct msghdr *mhdr)
        }
 #endif
        return(0);
-}
-
-/*
- * tvsub --
- *     Subtract 2 timeval structs:  out = out - in.  Out is assumed to
- * be >= in.
- */
-static void
-tvsub(struct timeval *out, struct timeval *in)
-{
-       if ((out->tv_usec -= in->tv_usec) < 0) {
-               --out->tv_sec;
-               out->tv_usec += 1000000;
-       }
-       out->tv_sec -= in->tv_sec;
 }
 
 /*
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