Keep track of nameservers that timeout and use others preferably.
The number of timeouts since the last received packet is visible in /stats A.
This commit is contained in:
Jilles Tjoelker
parent
0ae330b43f
commit
0b53baf73b
89
src/res.c
89
src/res.c
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@ -60,7 +60,6 @@ struct reslist
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{
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rb_dlink_node node;
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int id;
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int sent; /* number of requests sent */
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time_t ttl;
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char type;
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char queryname[128]; /* name currently being queried */
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@ -68,6 +67,7 @@ struct reslist
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char sends; /* number of sends (>1 means resent) */
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time_t sentat;
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time_t timeout;
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unsigned int lastns; /* index of last server sent to */
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struct rb_sockaddr_storage addr;
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char *name;
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struct DNSQuery *query; /* query callback for this request */
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@ -75,6 +75,7 @@ struct reslist
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static rb_fde_t *res_fd;
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static rb_dlink_list request_list = { NULL, NULL, 0 };
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static int ns_timeout_count[IRCD_MAXNS];
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static void rem_request(struct reslist *request);
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static struct reslist *make_request(struct DNSQuery *query);
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@ -131,7 +132,10 @@ static int res_ourserver(const struct rb_sockaddr_storage *inp)
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sizeof(struct in6_addr)) == 0) ||
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(memcmp(&v6->sin6_addr.s6_addr, &in6addr_any,
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sizeof(struct in6_addr)) == 0))
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{
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ns_timeout_count[ns] = 0;
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return 1;
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}
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break;
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#endif
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case AF_INET:
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@ -139,7 +143,10 @@ static int res_ourserver(const struct rb_sockaddr_storage *inp)
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if (v4->sin_port == v4in->sin_port)
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if ((v4->sin_addr.s_addr == INADDR_ANY)
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|| (v4->sin_addr.s_addr == v4in->sin_addr.s_addr))
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{
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ns_timeout_count[ns] = 0;
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return 1;
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}
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break;
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default:
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break;
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@ -176,6 +183,7 @@ static time_t timeout_query_list(time_t now)
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}
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else
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{
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ns_timeout_count[request->lastns]++;
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request->sentat = now;
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request->timeout += request->timeout;
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resend_query(request);
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@ -207,7 +215,11 @@ static struct ev_entry *timeout_resolver_ev = NULL;
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*/
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static void start_resolver(void)
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{
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int i;
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irc_res_init();
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for (i = 0; i < irc_nscount; i++)
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ns_timeout_count[i] = 0;
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if (res_fd == NULL)
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{
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@ -315,33 +327,67 @@ void delete_resolver_queries(const struct DNSQuery *query)
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}
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/*
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* send_res_msg - sends msg to all nameservers found in the "_res" structure.
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* This should reflect /etc/resolv.conf. We will get responses
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* which arent needed but is easier than checking to see if nameserver
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* isnt present. Returns number of messages successfully sent to
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* nameservers or -1 if no successful sends.
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* retryfreq - determine how many queries to wait before resending
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* if there have been that many consecutive timeouts
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*/
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static int retryfreq(int timeouts)
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{
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switch (timeouts)
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{
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case 1:
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return 3;
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case 2:
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return 9;
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case 3:
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return 27;
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case 4:
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return 81;
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default:
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return 243;
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}
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}
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/*
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* send_res_msg - sends msg to a nameserver.
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* This should reflect /etc/resolv.conf.
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* Returns number of nameserver successfully sent to
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* or -1 if no successful sends.
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*/
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static int send_res_msg(const char *msg, int len, int rcount)
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{
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int i;
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int sent = 0;
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int max_queries = IRCD_MIN(irc_nscount, rcount);
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int ns;
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static int retrycnt;
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/* RES_PRIMARY option is not implemented
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* if (res.options & RES_PRIMARY || 0 == max_queries)
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retrycnt++;
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/* First try a nameserver that seems to work.
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* Every once in a while, try a possibly broken one to check
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* if it is working again.
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*/
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if (max_queries == 0)
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max_queries = 1;
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for (i = 0; sent < max_queries && i < irc_nscount; i++)
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for (i = 0; i < irc_nscount; i++)
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{
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ns = (i + rcount - 1) % irc_nscount;
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if (ns_timeout_count[ns] && retrycnt % retryfreq(ns_timeout_count[ns]))
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continue;
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if (sendto(rb_get_fd(res_fd), msg, len, 0,
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(struct sockaddr *)&(irc_nsaddr_list[i]),
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GET_SS_LEN(&irc_nsaddr_list[i])) == len)
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++sent;
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(struct sockaddr *)&(irc_nsaddr_list[ns]),
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GET_SS_LEN(&irc_nsaddr_list[ns])) == len)
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return ns;
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}
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return (sent);
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/* No known working nameservers, try some broken one. */
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for (i = 0; i < irc_nscount; i++)
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{
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ns = (i + rcount - 1) % irc_nscount;
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if (!ns_timeout_count[ns])
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continue;
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if (sendto(rb_get_fd(res_fd), msg, len, 0,
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(struct sockaddr *)&(irc_nsaddr_list[ns]),
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GET_SS_LEN(&irc_nsaddr_list[ns])) == len)
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return ns;
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}
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return -1;
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}
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/*
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@ -465,6 +511,7 @@ static void query_name(struct reslist *request)
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{
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char buf[MAXPACKET];
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int request_len = 0;
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int ns;
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memset(buf, 0, sizeof(buf));
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@ -498,7 +545,9 @@ static void query_name(struct reslist *request)
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request->id = header->id;
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++request->sends;
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request->sent += send_res_msg(buf, request_len, request->sends);
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ns = send_res_msg(buf, request_len, request->sends);
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if (ns != -1)
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request->lastns = ns;
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}
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}
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@ -832,6 +881,6 @@ void report_dns_servers(struct Client *source_p)
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ipaddr, sizeof ipaddr))
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rb_strlcpy(ipaddr, "?", sizeof ipaddr);
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sendto_one_numeric(source_p, RPL_STATSDEBUG,
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"A %s", ipaddr);
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"A %s %d", ipaddr, ns_timeout_count[i]);
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}
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}
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