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>

diff --git a/networking/ntpd.c b/networking/ntpd.c
index 4695c336653154a0411eddf4a091d3ecce780e2a..517806e7514aa971d455402e88a1379cebb56dad 100644 (file)
--- 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); */