DNS name resolver improvements
- Cache intermediate CNAME records
- Bug fixes
Change-Id: I06dcb558212fc5e9434281493c872577cf9b83e1
Signed-off-by: Dave Barach <dave@barachs.net>
diff --git a/src/vnet/dns/dns.c b/src/vnet/dns/dns.c
index 90079e1..71ae7bb 100644
--- a/src/vnet/dns/dns.c
+++ b/src/vnet/dns/dns.c
@@ -523,6 +523,10 @@
u8 *request;
u32 qp_offset;
+ /* This can easily happen if sitting in GDB, etc. */
+ if (ep->flags & DNS_CACHE_ENTRY_FLAG_VALID)
+ return;
+
/* Construct the dns request, if we haven't been here already */
if (vec_len (ep->dns_request) == 0)
{
@@ -628,7 +632,6 @@
return VNET_API_ERROR_NO_SUCH_ENTRY;
ep = pool_elt_at_index (dm->entries, index);
-
if (!(ep->flags & DNS_CACHE_ENTRY_FLAG_VALID))
{
for (i = 0; i < vec_len (dm->unresolved_entries); i++)
@@ -772,6 +775,7 @@
*retp = 0;
dns_cache_lock (dm);
+search_again:
p = hash_get_mem (dm->cache_entry_by_name, name);
if (p)
{
@@ -782,18 +786,70 @@
if (((ep->flags & DNS_CACHE_ENTRY_FLAG_STATIC) == 0)
&& (now > ep->expiration_time))
{
- clib_warning ("Re-resolve %s", name);
+ int i;
+ u32 *indices_to_delete = 0;
+
+ /*
+ * Take out the rest of the resolution chain
+ * This isn't optimal, but it won't happen very often.
+ */
+ while (ep)
+ {
+ if ((ep->flags & DNS_CACHE_ENTRY_FLAG_CNAME))
+ {
+ vec_add1 (indices_to_delete, ep - dm->entries);
+
+ p = hash_get_mem (dm->cache_entry_by_name, ep->cname);
+ if (!p)
+ break;
+ ep = pool_elt_at_index (dm->entries, p[0]);
+ }
+ else
+ {
+ vec_add1 (indices_to_delete, ep - dm->entries);
+ break;
+ }
+ }
+ for (i = 0; i < vec_len (indices_to_delete); i++)
+ {
+ /* Reenable to watch re-resolutions */
+ if (0)
+ {
+ ep = pool_elt_at_index (dm->entries,
+ indices_to_delete[i]);
+ clib_warning ("Re-resolve %s", ep->name);
+ }
+
+ vnet_dns_delete_entry_by_index_nolock
+ (dm, indices_to_delete[i]);
+ }
+ vec_free (indices_to_delete);
/* Yes, kill it... */
- vnet_dns_delete_entry_by_index_nolock (dm, p[0]);
goto re_resolve;
}
+ if (ep->flags & DNS_CACHE_ENTRY_FLAG_CNAME)
+ {
+ name = ep->cname;
+ goto search_again;
+ }
+
/* Note: caller must drop the lock! */
*retp = ep;
return (0);
}
+ else
+ {
+ /*
+ * Resolution pending. Add request to the pending vector(s) */
+ vec_add1 (ep->api_clients_to_notify, client_index);
+ vec_add1 (ep->api_client_contexts, client_context);
+ dns_cache_unlock (dm);
+ return (0);
+ }
}
+re_resolve:
if (pool_elts (dm->entries) == dm->name_cache_size)
{
/* Will only fail if the cache is totally filled w/ static entries... */
@@ -805,7 +861,6 @@
}
}
-re_resolve:
/* add new hash table entry */
pool_get (dm->entries, ep);
memset (ep, 0, sizeof (*ep));
@@ -820,18 +875,22 @@
vec_add1 (ep->api_client_contexts, client_context);
vnet_send_dns_request (dm, ep);
dns_cache_unlock (dm);
-
return 0;
}
+#define foreach_notification_to_move \
+_(api_clients_to_notify) \
+_(api_client_contexts) \
+_(ip4_peers_to_notify) \
+_(ip6_peers_to_notify)
+
/**
* Handle cname indirection. JFC. Called with the cache locked.
* returns 0 if the reply is not a CNAME.
*/
int
-vnet_dns_cname_indirection_nolock (dns_main_t * dm, dns_cache_entry_t * ep,
- u8 * reply)
+vnet_dns_cname_indirection_nolock (dns_main_t * dm, u32 ep_index, u8 * reply)
{
dns_header_t *h;
dns_query_t *qp;
@@ -844,6 +903,8 @@
u32 qp_offset;
u16 flags;
u16 rcode;
+ dns_cache_entry_t *ep, *next_ep;
+ f64 now;
h = (dns_header_t *) reply;
flags = clib_net_to_host_u16 (h->flags);
@@ -891,11 +952,55 @@
if (clib_net_to_host_u16 (rr->type) != DNS_TYPE_CNAME)
return 0;
- /* Crap. Chase the CNAME name chain. */
+ /* This is a CNAME record, chase the name chain. */
+ /* The last request is no longer pending.. */
+ for (i = 0; i < vec_len (dm->unresolved_entries); i++)
+ if (ep_index == dm->unresolved_entries[i])
+ {
+ vec_delete (dm->unresolved_entries, 1, i);
+ goto found_last_request;
+ }
+ clib_warning ("pool elt %d supposedly pending, but not found...", ep_index);
+
+found_last_request:
+
+ now = vlib_time_now (dm->vlib_main);
cname = labels_to_name (rr->rdata, reply, &pos2);
+ /* Save the cname */
+ vec_add1 (cname, 0);
+ _vec_len (cname) -= 1;
+ ep = pool_elt_at_index (dm->entries, ep_index);
+ ep->cname = cname;
+ ep->flags |= (DNS_CACHE_ENTRY_FLAG_CNAME | DNS_CACHE_ENTRY_FLAG_VALID);
+ /* Save the response */
+ ep->dns_response = reply;
+ /* Set up expiration time */
+ ep->expiration_time = now + clib_net_to_host_u32 (rr->ttl);
+
+ pool_get (dm->entries, next_ep);
+
+ /* Need to recompute ep post pool-get */
+ ep = pool_elt_at_index (dm->entries, ep_index);
+
+ memset (next_ep, 0, sizeof (*next_ep));
+ next_ep->name = vec_dup (cname);
+ vec_add1 (next_ep->name, 0);
+ _vec_len (next_ep->name) -= 1;
+
+ hash_set_mem (dm->cache_entry_by_name, next_ep->name,
+ next_ep - dm->entries);
+
+ /* Use the same server */
+ next_ep->server_rotor = ep->server_rotor;
+ next_ep->server_af = ep->server_af;
+
+ /* Move notification data to the next name in the chain */
+#define _(a) next_ep->a = ep->a; ep->a = 0;
+ foreach_notification_to_move;
+#undef _
+
request = name_to_labels (cname);
- vec_free (cname);
qp_offset = vec_len (request);
@@ -913,7 +1018,7 @@
h = (dns_header_t *) request;
/* Transaction ID = pool index */
- h->id = clib_host_to_net_u16 (ep - dm->entries);
+ h->id = clib_host_to_net_u16 (next_ep - dm->entries);
/* Ask for a recursive lookup */
h->flags = clib_host_to_net_u16 (DNS_RD | DNS_OPCODE_QUERY);
@@ -921,22 +1026,17 @@
h->nscount = 0;
h->arcount = 0;
- vec_free (ep->dns_request);
- ep->dns_request = request;
- ep->retry_timer = vlib_time_now (dm->vlib_main) + 2.0;
- ep->retry_count = 0;
+ next_ep->dns_request = request;
+ next_ep->retry_timer = now + 2.0;
+ next_ep->retry_count = 0;
/*
* Enable this to watch recursive resolution happen...
* fformat (stdout, "%U", format_dns_reply, request, 2);
*/
- if (ep->server_af == 1 /* ip6 */ )
- send_dns6_request (dm, ep, dm->ip6_name_servers + ep->server_rotor);
- else
- send_dns4_request (dm, ep, dm->ip4_name_servers + ep->server_rotor);
-
- vec_free (reply);
+ vec_add1 (dm->unresolved_entries, next_ep - dm->entries);
+ vnet_send_dns_request (dm, next_ep);
return (1);
}
@@ -1461,6 +1561,31 @@
pos += sizeof (*rr) + clib_net_to_host_u16 (rr->rdlength);
break;
+ case DNS_TYPE_HINFO:
+ {
+ /* Two counted strings. DGMS */
+ u8 *len;
+ u8 *curpos;
+ int i;
+ if (verbose > 1)
+ {
+ s = format (s, "HINFO: ");
+ len = rr->rdata;
+ curpos = len + 1;
+ for (i = 0; i < *len; i++)
+ vec_add1 (s, *curpos++);
+
+ vec_add1 (s, ' ');
+ len = curpos++;
+ for (i = 0; i < *len; i++)
+ vec_add1 (s, *curpos++);
+
+ vec_add1 (s, '\n');
+ }
+ }
+ pos += sizeof (*rr) + clib_net_to_host_u16 (rr->rdlength);
+ break;
+
case DNS_TYPE_NAMESERVER:
if (verbose > 1)
{
@@ -1700,8 +1825,11 @@
else
ss = " ";
- s = format (s, "%s%s -> %U", ss, ep->name,
- format_dns_reply, ep->dns_response, verbose);
+ if (verbose < 2 && ep->flags & DNS_CACHE_ENTRY_FLAG_CNAME)
+ s = format (s, "%s%s -> %s", ss, ep->name, ep->cname);
+ else
+ s = format (s, "%s%s -> %U", ss, ep->name,
+ format_dns_reply, ep->dns_response, verbose);
if (!(ep->flags & DNS_CACHE_ENTRY_FLAG_STATIC))
{
f64 time_left = ep->expiration_time - now;
@@ -1733,10 +1861,13 @@
else
ss = " ";
- s = format (s, "%s%s -> %U", ss, ep->name,
- format_dns_reply,
- ep->dns_response,
- verbose);
+ if (verbose < 2 && ep->flags & DNS_CACHE_ENTRY_FLAG_CNAME)
+ s = format (s, "%s%s -> %s", ss, ep->name, ep->cname);
+ else
+ s = format (s, "%s%s -> %U", ss, ep->name,
+ format_dns_reply,
+ ep->dns_response,
+ verbose);
if (!(ep->flags & DNS_CACHE_ENTRY_FLAG_STATIC))
{
f64 time_left = ep->expiration_time - now;
@@ -1744,6 +1875,10 @@
s = format (s, " TTL left %.1f", time_left);
else
s = format (s, " EXPIRED");
+
+ if (verbose > 2)
+ s = format (s, " %d client notifications pending\n",
+ vec_len(ep->api_clients_to_notify));
}
}
else
@@ -2103,6 +2238,50 @@
.function = test_dns_unfmt_command_fn,
};
/* *INDENT-ON* */
+
+static clib_error_t *
+test_dns_expire_command_fn (vlib_main_t * vm,
+ unformat_input_t * input,
+ vlib_cli_command_t * cmd)
+{
+ dns_main_t *dm = &dns_main;
+ u8 *name;
+ uword *p;
+ clib_error_t *e;
+ dns_cache_entry_t *ep;
+
+ if (unformat (input, "%v", &name))
+ {
+ vec_add1 (name, 0);
+ _vec_len (name) -= 1;
+ }
+
+ dns_cache_lock (dm);
+
+ p = hash_get_mem (dm->cache_entry_by_name, name);
+ if (!p)
+ {
+ dns_cache_unlock (dm);
+ e = clib_error_return (0, "%s is not in the cache...", name);
+ vec_free (name);
+ return e;
+ }
+
+ ep = pool_elt_at_index (dm->entries, p[0]);
+
+ ep->expiration_time = 0;
+
+ return 0;
+}
+
+/* *INDENT-OFF* */
+VLIB_CLI_COMMAND (test_dns_expire_command) =
+{
+ .path = "test dns expire",
+ .short_help = "test dns expire <name>",
+ .function = test_dns_expire_command_fn,
+};
+/* *INDENT-ON* */
#endif
/*