b62ea34af
Natanael Copa
2017-01-06
Subject
ntpd: improve postponed hostname resolution
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networking/ntpd.c+34 -39
| @@ -155,6 +155,7 @@ | |
| #define RETRY_INTERVAL 32 /* on send/recv error, retry in N secs (need to be power of 2) */ | |
| #define NOREPLY_INTERVAL 512 /* sent, but got no reply: cap next query by this many seconds */ | |
| #define RESPONSE_INTERVAL 16 /* wait for reply up to N secs */ | |
| + | #define HOSTNAME_INTERVAL 5 /* hostname lookup failed. Wait N secs for next try */ |
| /* Step threshold (sec). std ntpd uses 0.128. | |
| */ | |
| @@ -790,28 +791,20 @@ reset_peer_stats(peer_t *p, double offset) | |
| VERB6 bb_error_msg("%s->lastpkt_recv_time=%f", p->p_dotted, p->lastpkt_recv_time); | |
| } | |
| - | static void |
| - | resolve_peer_hostname(peer_t *p, int loop_on_fail) |
| + | static len_and_sockaddr* |
| + | resolve_peer_hostname(peer_t *p) |
| { | |
| - | 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; |
| + | len_and_sockaddr *lsa = host2sockaddr(p->p_hostname, 123); |
| + | if (lsa) { |
| + | free(p->p_lsa); |
| + | free(p->p_dotted); |
| + | p->p_lsa = lsa; |
| + | p->p_dotted = xmalloc_sockaddr2dotted_noport(&lsa->u.sa); |
| + | } else { |
| + | /* error message is emitted by host2sockaddr() */ |
| + | set_next(p, HOSTNAME_INTERVAL); |
| } | |
| - | free(p->p_lsa); |
| - | free(p->p_dotted); |
| - | p->p_lsa = lsa; |
| - | p->p_dotted = xmalloc_sockaddr2dotted_noport(&lsa->u.sa); |
| + | return lsa; |
| } | |
| static void | |
| @@ -822,28 +815,28 @@ add_peers(const char *s) | |
| p = xzalloc(sizeof(*p) + strlen(s)); | |
| strcpy(p->p_hostname, s); | |
| - | resolve_peer_hostname(p, /*loop_on_fail=*/ 1); |
| + | 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); */ |
| + | reset_peer_stats(p, STEP_THRESHOLD); |
| /* 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->p_lsa); |
| - | free(p->p_dotted); |
| - | free(p); |
| - | return; |
| + | if (resolve_peer_hostname(p)) { |
| + | for (item = G.ntp_peers; item != NULL; item = item->link) { |
| + | peer_t *pp = (peer_t *) item->data; |
| + | if (pp->p_dotted && strcmp(p->p_dotted, pp->p_dotted) == 0) { |
| + | bb_error_msg("duplicate peer %s (%s)", s, p->p_dotted); |
| + | free(p->p_lsa); |
| + | free(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); */ |
| - | reset_peer_stats(p, STEP_THRESHOLD); |
| - | |
| llist_add_to(&G.ntp_peers, p); | |
| G.peer_cnt++; | |
| } | |
| @@ -871,6 +864,11 @@ do_sendto(int fd, | |
| static void | |
| send_query_to_peer(peer_t *p) | |
| { | |
| + | if (!p->p_lsa) { |
| + | if (!resolve_peer_hostname(p)) |
| + | return; |
| + | } |
| + | |
| /* Why do we need to bind()? | |
| * See what happens when we don't bind: | |
| * | |
| @@ -2238,7 +2236,7 @@ static NOINLINE void ntp_init(char **argv) | |
| IF_FEATURE_NTPD_SERVER("I:") /* compat */ | |
| "d" /* compat */ | |
| "46aAbgL", /* compat, ignored */ | |
| - | &peers,&G.script_name, |
| + | &peers, &G.script_name, |
| #if ENABLE_FEATURE_NTPD_SERVER | |
| &G.if_name, | |
| #endif | |
| @@ -2263,9 +2261,6 @@ static NOINLINE void ntp_init(char **argv) | |
| if (opts & OPT_N) | |
| setpriority(PRIO_PROCESS, 0, -15); | |
| - | /* add_peers() calls can retry DNS resolution (possibly forever). |
| - | * Daemonize before them, or else boot can stall forever. |
| - | */ |
| if (!(opts & OPT_n)) { | |
| bb_daemonize_or_rexec(DAEMON_DEVNULL_STDIO, argv); | |
| logmode = LOGMODE_NONE; | |
| @@ -2400,7 +2395,7 @@ int ntpd_main(int argc UNUSED_PARAM, char **argv) | |
| /* What if don't see it because it changed its IP? */ | |
| if (p->reachable_bits == 0) | |
| - | resolve_peer_hostname(p, /*loop_on_fail=*/ 0); |
| + | resolve_peer_hostname(p); |
| set_next(p, timeout); | |
| } | |