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authorDenys Vlasenko2016-06-06 02:26:49 +0200
committerDenys Vlasenko2016-06-06 02:26:49 +0200
commite4caf1dd9ce8569371a0eeb77ccf02a572dc0f11 (patch)
tree9bb0c538b7bac20b94272c39576b740436a08c6c
parentb684d1b1864ba9d7968de5565823f8e42f1dc448 (diff)
downloadbusybox-e4caf1dd9ce8569371a0eeb77ccf02a572dc0f11.zip
busybox-e4caf1dd9ce8569371a0eeb77ccf02a572dc0f11.tar.gz
ntpd: retry initial DNS resolution (forever, no timeout for now).
Some users start ntpd on boot, and don't babysit it. If it dies because DNS is not yet up and therefore NTP servers can't be found, users are not happy. Example behavior with a peer name which can't be resolved: ntpd: bad address 'qwe.rty.ghj.kl' ...5 sec... ntpd: bad address 'qwe.rty.ghj.kl' ntpd: bad address 'qwe.rty.ghj.kl' ntpd: bad address 'qwe.rty.ghj.kl' ntpd: bad address 'qwe.rty.ghj.kl' ntpd: bad address 'qwe.rty.ghj.kl' ntpd: bad address 'qwe.rty.ghj.kl' ntpd: bad address 'qwe.rty.ghj.kl' ntpd: bad address 'qwe.rty.ghj.kl' ntpd: bad address 'qwe.rty.ghj.kl' ... Based on the patch by Kaarle Ritvanen <kaarle.ritvanen@datakunkku.fi> function old new delta resolve_peer_hostname - 81 +81 ntpd_main 1130 1061 -69 ------------------------------------------------------------------------------ (add/remove: 1/0 grow/shrink: 0/1 up/down: 81/-69) Total: 12 bytes Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
-rw-r--r--networking/ntpd.c47
1 files changed, 30 insertions, 17 deletions
diff --git a/networking/ntpd.c b/networking/ntpd.c
index 4103189..98158a3 100644
--- a/networking/ntpd.c
+++ b/networking/ntpd.c
@@ -267,7 +267,6 @@ typedef struct {
typedef struct {
len_and_sockaddr *p_lsa;
- char *p_hostname;
char *p_dotted;
int p_fd;
int datapoint_idx;
@@ -293,6 +292,7 @@ typedef struct {
datapoint_t filter_datapoint[NUM_DATAPOINTS];
/* last sent packet: */
msg_t p_xmt_msg;
+ char p_hostname[1];
} peer_t;
@@ -765,14 +765,38 @@ reset_peer_stats(peer_t *p, double offset)
}
static void
+resolve_peer_hostname(peer_t *p, int loop_on_fail)
+{
+ len_and_sockaddr *lsa;
+
+ again:
+ lsa = host2sockaddr(p->p_hostname, 123);
+ if (!lsa) {
+ /* error message already emitted by host2sockaddr() */
+ if (!loop_on_fail)
+ return;
+//FIXME: do this to avoid infinite looping on typo in a hostname?
+//well... in which case, what is a good value for loop_on_fail?
+ //if (--loop_on_fail == 0)
+ // xfunc_die();
+ sleep(5);
+ goto again;
+ }
+ free(p->p_lsa);
+ free(p->p_dotted);
+ p->p_lsa = lsa;
+ p->p_dotted = xmalloc_sockaddr2dotted_noport(&lsa->u.sa);
+}
+
+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);
+ p = xzalloc(sizeof(*p) + strlen(s));
+ strcpy(p->p_hostname, s);
+ resolve_peer_hostname(p, /*loop_on_fail=*/ 1);
/* Names like N.<country2chars>.pool.ntp.org are randomly resolved
* to a pool of machines. Sometimes different N's resolve to the same IP.
@@ -789,7 +813,6 @@ add_peers(const char *s)
}
}
- p->p_hostname = xstrdup(s);
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); */
@@ -2338,18 +2361,8 @@ int ntpd_main(int argc UNUSED_PARAM, char **argv)
p->p_dotted, p->reachable_bits, timeout);
/* What if don't see it because it changed its IP? */
- if (p->reachable_bits == 0) {
- len_and_sockaddr *lsa = host2sockaddr(p->p_hostname, 123);
- if (lsa) {
- char *dotted = xmalloc_sockaddr2dotted_noport(&lsa->u.sa);
- //if (strcmp(dotted, p->p_dotted) != 0)
- // bb_error_msg("peer IP changed");
- free(p->p_lsa);
- free(p->p_dotted);
- p->p_lsa = lsa;
- p->p_dotted = dotted;
- }
- }
+ if (p->reachable_bits == 0)
+ resolve_peer_hostname(p, /*loop_on_fail=*/ 0);
set_next(p, timeout);
}