ntpd: on time step, kill all outstanding replies from other peers

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>

1 files changed, 30 insertions, 20 deletions

diff --git a/networking/ntpd.c b/networking/ntpd.c
index 603801ec6..72e9d0be2 100644
--- a/networking/ntpd.c
+++ b/networking/ntpd.c
@@ -220,14 +220,14 @@ typedef struct {
 typedef struct {
         len_and_sockaddr *p_lsa;
         char             *p_dotted;
-        /* when to send new query (if p_fd == -1)
-         * or when receive times out (if p_fd >= 0): */
         int              p_fd;
         int              datapoint_idx;
         uint32_t         lastpkt_refid;
         uint8_t          lastpkt_status;
         uint8_t          lastpkt_stratum;
         uint8_t          reachable_bits;
+        /* when to send new query (if p_fd == -1)
+         * or when receive times out (if p_fd >= 0): */
         double           next_action_time;
         double           p_xmttime;
         double           lastpkt_recv_time;
@@ -895,6 +895,11 @@ step_time(double offset)
 
         /* Correct various fields which contain time-relative values: */
 
+        /* Globals: */
+        G.cur_time += offset;
+        G.last_update_recv_time += offset;
+        G.last_script_run += offset;
+
         /* p->lastpkt_recv_time, p->next_action_time and such: */
         for (item = G.ntp_peers; item != NULL; item = item->link) {
                 peer_t *pp = (peer_t *) item->data;
@@ -902,11 +907,16 @@ step_time(double offset)
                 //bb_error_msg("offset:%+f pp->next_action_time:%f -> %f",
                 //      offset, pp->next_action_time, pp->next_action_time + offset);
                 pp->next_action_time += offset;
+                if (pp->p_fd >= 0) {
+                        /* We wait for reply from this peer too.
+                         * But due to step we are doing, reply's data is no longer
+                         * useful (in fact, it'll be bogus). Stop waiting for it.
+                         */
+                        close(pp->p_fd);
+                        pp->p_fd = -1;
+                        set_next(pp, RETRY_INTERVAL);
+                }
         }
-        /* Globals: */
-        G.cur_time += offset;
-        G.last_update_recv_time += offset;
-        G.last_script_run += offset;
 }
 
 
@@ -1623,22 +1633,30 @@ recv_and_process_peer_pkt(peer_t *p)
                 ) {
 //TODO: always do this?
                         interval = retry_interval();
-                        goto set_next_and_close_sock;
+                        goto set_next_and_ret;
                 }
                 xfunc_die();
         }
 
         if (size != NTP_MSGSIZE_NOAUTH && size != NTP_MSGSIZE) {
                 bb_error_msg("malformed packet received from %s", p->p_dotted);
-                goto bail;
+                return;
         }
 
         if (msg.m_orgtime.int_partl != p->p_xmt_msg.m_xmttime.int_partl
          || msg.m_orgtime.fractionl != p->p_xmt_msg.m_xmttime.fractionl
         ) {
-                goto bail;
+                /* Somebody else's packet */
+                return;
         }
 
+        /* We do not expect any more packets from this peer for now.
+         * Closing the socket informs kernel about it.
+         * We open a new socket when we send a new query.
+         */
+        close(p->p_fd);
+        p->p_fd = -1;
+
         if ((msg.m_status & LI_ALARM) == LI_ALARM
          || msg.m_stratum == 0
          || msg.m_stratum > NTP_MAXSTRATUM
@@ -1647,8 +1665,8 @@ recv_and_process_peer_pkt(peer_t *p)
 // "DENY", "RSTR" - peer does not like us at all
 // "RATE" - peer is overloaded, reduce polling freq
                 interval = poll_interval(0);
-                bb_error_msg("reply from %s: not synced, next query in %us", p->p_dotted, interval);
-                goto set_next_and_close_sock;
+                bb_error_msg("reply from %s: peer is unsynced, next query in %us", p->p_dotted, interval);
+                goto set_next_and_ret;
         }
 
 //      /* Verify valid root distance */
@@ -1794,16 +1812,8 @@ recv_and_process_peer_pkt(peer_t *p)
         /* Decide when to send new query for this peer */
         interval = poll_interval(0);
 
- set_next_and_close_sock:
+ set_next_and_ret:
         set_next(p, interval);
-        /* We do not expect any more packets from this peer for now.
-         * Closing the socket informs kernel about it.
-         * We open a new socket when we send a new query.
-         */
-        close(p->p_fd);
-        p->p_fd = -1;
- bail:
-        return;
 }
 
 #if ENABLE_FEATURE_NTPD_SERVER