ntpd: truly ignore high delay packet

[oweals/busybox.git] / networking / ntpd.c

diff --git a/networking/ntpd.c b/networking/ntpd.c
index 44592ce548c130447e2bdc07f7dc05726ec9a0b5..2eec99f99f0fc1a48c6e5700e143bfd405692239 100644 (file)
--- a/networking/ntpd.c
+++ b/networking/ntpd.c
@@ -42,6 +42,13 @@
 //usage:       )
 //usage:     "\n       -S PROG Run PROG after stepping time, stratum change, and every 11 mins"
 //usage:     "\n       -p PEER Obtain time from PEER (may be repeated)"
+//usage:       IF_FEATURE_NTPD_CONF(
+//usage:     "\n               If -p is not given, read /etc/ntp.conf"
+//usage:       )
+
+// -l and -p options are not compatible with "standard" ntpd:
+// it has them as "-l logfile" and "-p pidfile".
+// -S and -w are not compat either, "standard" ntpd has no such opts.
 
 #include "libbb.h"
 #include <math.h>
@@ -245,6 +252,9 @@ typedef struct {
         * or when receive times out (if p_fd >= 0): */
        double           next_action_time;
        double           p_xmttime;
+       double           p_raw_delay;
+       /* p_raw_delay is set even by "high delay" packets */
+       /* lastpkt_delay isn't */
        double           lastpkt_recv_time;
        double           lastpkt_delay;
        double           lastpkt_rootdelay;
@@ -730,7 +740,7 @@ reset_peer_stats(peer_t *p, double offset)
 }
 
 static void
-add_peers(char *s)
+add_peers(const char *s)
 {
        peer_t *p;
 
@@ -1678,7 +1688,8 @@ recv_and_process_peer_pkt(peer_t *p)
        ssize_t     size;
        msg_t       msg;
        double      T1, T2, T3, T4;
-       double      dv, offset;
+       double      offset;
+       double      prev_delay, delay;
        unsigned    interval;
        datapoint_t *datapoint;
        peer_t      *q;
@@ -1738,12 +1749,6 @@ recv_and_process_peer_pkt(peer_t *p)
 //     if (msg.m_rootdelay / 2 + msg.m_rootdisp >= MAXDISP || p->lastpkt_reftime > msg.m_xmt)
 //             return;                 /* invalid header values */
 
-       p->lastpkt_status = msg.m_status;
-       p->lastpkt_stratum = msg.m_stratum;
-       p->lastpkt_rootdelay = sfp_to_d(msg.m_rootdelay);
-       p->lastpkt_rootdisp = sfp_to_d(msg.m_rootdisp);
-       p->lastpkt_refid = msg.m_refid;
-
        /*
         * From RFC 2030 (with a correction to the delay math):
         *
@@ -1763,28 +1768,35 @@ recv_and_process_peer_pkt(peer_t *p)
        T3 = lfp_to_d(msg.m_xmttime);
        T4 = G.cur_time;
 
-       p->lastpkt_recv_time = T4;
-       VERB6 bb_error_msg("%s->lastpkt_recv_time=%f", p->p_dotted, p->lastpkt_recv_time);
-
        /* The delay calculation is a special case. In cases where the
         * server and client clocks are running at different rates and
         * with very fast networks, the delay can appear negative. In
         * order to avoid violating the Principle of Least Astonishment,
         * the delay is clamped not less than the system precision.
         */
-       dv = p->lastpkt_delay;
-       p->lastpkt_delay = (T4 - T1) - (T3 - T2);
-       if (p->lastpkt_delay < G_precision_sec)
-               p->lastpkt_delay = G_precision_sec;
+       delay = (T4 - T1) - (T3 - T2);
+       if (delay < G_precision_sec)
+               delay = G_precision_sec;
        /*
         * If this packet's delay is much bigger than the last one,
         * it's better to just ignore it than use its much less precise value.
         */
-       if (p->reachable_bits && p->lastpkt_delay > dv * BAD_DELAY_GROWTH) {
+       prev_delay = p->p_raw_delay;
+       p->p_raw_delay = delay;
+       if (p->reachable_bits && delay > prev_delay * BAD_DELAY_GROWTH) {
                bb_error_msg("reply from %s: delay %f is too high, ignoring", p->p_dotted, p->lastpkt_delay);
                goto pick_normal_interval;
        }
 
+       p->lastpkt_delay = delay;
+       p->lastpkt_recv_time = T4;
+       VERB6 bb_error_msg("%s->lastpkt_recv_time=%f", p->p_dotted, p->lastpkt_recv_time);
+       p->lastpkt_status = msg.m_status;
+       p->lastpkt_stratum = msg.m_stratum;
+       p->lastpkt_rootdelay = sfp_to_d(msg.m_rootdelay);
+       p->lastpkt_rootdisp = sfp_to_d(msg.m_rootdisp);
+       p->lastpkt_refid = msg.m_refid;
+
        p->datapoint_idx = p->reachable_bits ? (p->datapoint_idx + 1) % NUM_DATAPOINTS : 0;
        datapoint = &p->filter_datapoint[p->datapoint_idx];
        datapoint->d_recv_time = T4;
@@ -2087,14 +2099,34 @@ static NOINLINE void ntp_init(char **argv)
                        "d" /* compat */
                        "46aAbgL", /* compat, ignored */
                        &peers, &G.script_name, &G.verbose);
-       if (!(opts & (OPT_p|OPT_l)))
-               bb_show_usage();
+
 //     if (opts & OPT_x) /* disable stepping, only slew is allowed */
 //             G.time_was_stepped = 1;
        if (peers) {
                while (peers)
                        add_peers(llist_pop(&peers));
-       } else {
+       }
+#if ENABLE_FEATURE_NTPD_CONF
+       else {
+               parser_t *parser;
+               char *token[3];
+
+               parser = config_open("/etc/ntp.conf");
+               while (config_read(parser, token, 3, 1, "# \t", PARSE_NORMAL)) {
+                       if (strcmp(token[0], "server") == 0 && token[1]) {
+                               add_peers(token[1]);
+                               continue;
+                       }
+                       bb_error_msg("skipping %s:%u: unimplemented command '%s'",
+                               "/etc/ntp.conf", parser->lineno, token[0]
+                       );
+               }
+               config_close(parser);
+       }
+#endif
+       if (G.peer_cnt == 0) {
+               if (!(opts & OPT_l))
+                       bb_show_usage();
                /* -l but no peers: "stratum 1 server" mode */
                G.stratum = 1;
        }