ntpd: do not use a peer more than once (say, if two peers resolve to the same IP)

function                                             old     new   delta
add_peers                                             98     166     +68

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

1 files changed, 16 insertions, 1 deletions

diff --git a/networking/ntpd.c b/networking/ntpd.c
index 4695c3366..517806e75 100644
--- a/networking/ntpd.c
+++ b/networking/ntpd.c
@@ -727,7 +727,7 @@ reset_peer_stats(peer_t *p, double offset)
 
         /* Used to set p->filter_datapoint[i].d_dispersion = MAXDISP
          * and clear reachable bits, but this proved to be too agressive:
-         * after step (tested with suspinding laptop for ~30 secs),
+         * after step (tested with suspending laptop for ~30 secs),
          * this caused all previous data to be considered invalid,
          * making us needing to collect full ~8 datapoins per peer
          * after step in order to start trusting them.
@@ -766,11 +766,26 @@ reset_peer_stats(peer_t *p, double offset)
 static void
 add_peers(const char *s)
 {
+        llist_t *item;
         peer_t *p;
 
         p = xzalloc(sizeof(*p));
         p->p_lsa = xhost2sockaddr(s, 123);
         p->p_dotted = xmalloc_sockaddr2dotted_noport(&p->p_lsa->u.sa);
+
+        /* Names like N.<country2chars>.pool.ntp.org are randomly resolved
+         * to a pool of machines. Sometimes different N's resolve to the same IP.
+         * It is not useful to have two peers with same IP. We skip duplicates.
+         */
+        for (item = G.ntp_peers; item != NULL; item = item->link) {
+                peer_t *pp = (peer_t *) item->data;
+                if (strcmp(p->p_dotted, pp->p_dotted) == 0) {
+                        bb_error_msg("duplicate peer %s (%s)", s, p->p_dotted);
+                        free(p);
+                        return;
+                }
+        }
+
         p->p_fd = -1;
         p->p_xmt_msg.m_status = MODE_CLIENT | (NTP_VERSION << 3);
         p->next_action_time = G.cur_time; /* = set_next(p, 0); */