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authorDave Barach <dave@barachs.net>2018-01-09 17:00:00 -0500
committerDamjan Marion <dmarion.lists@gmail.com>2018-01-10 02:43:07 +0000
commit580eda7067bee891c00f59fe3927720def3837ec (patch)
treecf62ee4dd55c6c61adcff15917ab23059f02b17c
parentaec8f8984771cabc79a8ed64f56afcf61465d00a (diff)
Functional improvements, bug fixes
At least when testing against "known good" DNS servers: it turns out that sending 2x requests - one for an A-record and another for a AAAA-record - seems to work better than sending a single DNS_TYPE_ALL request. Fix c-string vs. u8 vector mistakes. Fix server failover. Change-Id: I26554f0a9c1744376f21372506ebec8658e351e2 Signed-off-by: Dave Barach <dave@barachs.net>
-rw-r--r--src/vnet/dns/dns.c104
-rw-r--r--src/vnet/dns/dns.h8
-rw-r--r--src/vnet/dns/request_node.c6
-rw-r--r--src/vnet/dns/resolver_process.c59
4 files changed, 152 insertions, 25 deletions
diff --git a/src/vnet/dns/dns.c b/src/vnet/dns/dns.c
index c4ba85105fc..7e6465b4eea 100644
--- a/src/vnet/dns/dns.c
+++ b/src/vnet/dns/dns.c
@@ -197,9 +197,9 @@ static void vl_api_dns_name_server_add_del_t_handler
REPLY_MACRO (VL_API_DNS_NAME_SERVER_ADD_DEL_REPLY);
}
-static void
-send_dns4_request (dns_main_t * dm,
- dns_cache_entry_t * ep, ip4_address_t * server)
+void
+vnet_dns_send_dns4_request (dns_main_t * dm,
+ dns_cache_entry_t * ep, ip4_address_t * server)
{
vlib_main_t *vm = dm->vlib_main;
f64 now = vlib_time_now (vm);
@@ -247,7 +247,7 @@ send_dns4_request (dns_main_t * dm,
{
clib_warning
("route to %U exists, fei %d, get_resolving_interface returned"
- " ~0", fei, format_ip4_address, &prefix.fp_addr);
+ " ~0", format_ip4_address, &prefix.fp_addr, fei);
return;
}
@@ -313,9 +313,9 @@ found_src_address:
ep->retry_timer = now + 2.0;
}
-static void
-send_dns6_request (dns_main_t * dm,
- dns_cache_entry_t * ep, ip6_address_t * server)
+void
+vnet_dns_send_dns6_request (dns_main_t * dm,
+ dns_cache_entry_t * ep, ip6_address_t * server)
{
vlib_main_t *vm = dm->vlib_main;
f64 now = vlib_time_now (vm);
@@ -517,11 +517,11 @@ vnet_send_dns_request (dns_main_t * dm, dns_cache_entry_t * ep)
dns_header_t *h;
dns_query_t *qp;
u16 tmp;
- u8 *request;
+ u8 *request, *name_copy;
u32 qp_offset;
/* This can easily happen if sitting in GDB, etc. */
- if (ep->flags & DNS_CACHE_ENTRY_FLAG_VALID)
+ if (ep->flags & DNS_CACHE_ENTRY_FLAG_VALID || ep->server_fails > 1)
return;
/* Construct the dns request, if we haven't been here already */
@@ -533,14 +533,29 @@ vnet_send_dns_request (dns_main_t * dm, dns_cache_entry_t * ep)
* per label is 63, enforce that.
*/
request = name_to_labels (ep->name);
+ name_copy = vec_dup (request);
qp_offset = vec_len (request);
+ /*
+ * At least when testing against "known good" DNS servers:
+ * it turns out that sending 2x requests - one for an A-record
+ * and another for a AAAA-record - seems to work better than
+ * sending a DNS_TYPE_ALL request.
+ */
+
/* Add space for the query header */
- vec_validate (request, qp_offset + sizeof (dns_query_t) - 1);
+ vec_validate (request, 2 * qp_offset + 2 * sizeof (dns_query_t) - 1);
qp = (dns_query_t *) (request + qp_offset);
- qp->type = clib_host_to_net_u16 (DNS_TYPE_ALL);
+ qp->type = clib_host_to_net_u16 (DNS_TYPE_A);
+ qp->class = clib_host_to_net_u16 (DNS_CLASS_IN);
+ qp++;
+ clib_memcpy (qp, name_copy, vec_len (name_copy));
+ qp = (dns_query_t *) (((u8 *) qp) + vec_len (name_copy));
+ vec_free (name_copy);
+
+ qp->type = clib_host_to_net_u16 (DNS_TYPE_AAAA);
qp->class = clib_host_to_net_u16 (DNS_CLASS_IN);
/* Punch in space for the dns_header_t */
@@ -554,7 +569,7 @@ vnet_send_dns_request (dns_main_t * dm, dns_cache_entry_t * ep)
/* Ask for a recursive lookup */
tmp = DNS_RD | DNS_OPCODE_QUERY;
h->flags = clib_host_to_net_u16 (tmp);
- h->qdcount = clib_host_to_net_u16 (1);
+ h->qdcount = clib_host_to_net_u16 (2);
h->nscount = 0;
h->arcount = 0;
@@ -570,8 +585,8 @@ vnet_send_dns_request (dns_main_t * dm, dns_cache_entry_t * ep)
{
if (vec_len (dm->ip6_name_servers))
{
- send_dns6_request (dm, ep,
- dm->ip6_name_servers + ep->server_rotor);
+ vnet_dns_send_dns6_request
+ (dm, ep, dm->ip6_name_servers + ep->server_rotor);
goto out;
}
else
@@ -579,7 +594,8 @@ vnet_send_dns_request (dns_main_t * dm, dns_cache_entry_t * ep)
}
if (vec_len (dm->ip4_name_servers))
{
- send_dns4_request (dm, ep, dm->ip4_name_servers + ep->server_rotor);
+ vnet_dns_send_dns4_request
+ (dm, ep, dm->ip4_name_servers + ep->server_rotor);
goto out;
}
}
@@ -606,9 +622,11 @@ vnet_send_dns_request (dns_main_t * dm, dns_cache_entry_t * ep)
}
if (ep->server_af == 1 /* ip6 */ )
- send_dns6_request (dm, ep, dm->ip6_name_servers + ep->server_rotor);
+ vnet_dns_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);
+ vnet_dns_send_dns4_request
+ (dm, ep, dm->ip4_name_servers + ep->server_rotor);
out:
@@ -947,7 +965,7 @@ vnet_dns_cname_indirection_nolock (dns_main_t * dm, u32 ep_index, u8 * reply)
case DNS_RCODE_SERVER_FAILURE:
case DNS_RCODE_NOT_IMPLEMENTED:
case DNS_RCODE_REFUSED:
- return 0;
+ return -1;
}
curpos = (u8 *) (h + 1);
@@ -971,12 +989,34 @@ vnet_dns_cname_indirection_nolock (dns_main_t * dm, u32 ep_index, u8 * reply)
else
return 0;
- rr = (dns_rr_t *) pos;
+ /* Walk the answer(s) to see what to do next */
+ for (i = 0; i < clib_net_to_host_u16 (h->anscount); i++)
+ {
+ rr = (dns_rr_t *) pos;
+ switch (clib_net_to_host_u16 (rr->type))
+ {
+ /* Real address record? Done.. */
+ case DNS_TYPE_A:
+ case DNS_TYPE_AAAA:
+ return 0;
+ /* Chase a CNAME pointer? */
+ case DNS_TYPE_CNAME:
+ goto chase_chain;
- /* This is a real record, not a CNAME record */
- if (clib_net_to_host_u16 (rr->type) != DNS_TYPE_CNAME)
- return 0;
+ /* Some other junk, e.g. a nameserver... */
+ default:
+ break;
+ }
+ pos += sizeof (*rr) + clib_net_to_host_u16 (rr->rdlength);
+ }
+ /* Neither a CNAME nor a real address. Try another server */
+ flags &= ~DNS_RCODE_MASK;
+ flags |= DNS_RCODE_NAME_ERROR;
+ h->flags = clib_host_to_net_u16 (flags);
+ return -1;
+
+chase_chain:
/* This is a CNAME record, chase the name chain. */
/* The last request is no longer pending.. */
@@ -999,6 +1039,8 @@ found_last_request:
ep->cname = cname;
ep->flags |= (DNS_CACHE_ENTRY_FLAG_CNAME | DNS_CACHE_ENTRY_FLAG_VALID);
/* Save the response */
+ if (ep->dns_response)
+ vec_free (ep->dns_response);
ep->dns_response = reply;
/* Set up expiration time */
ep->expiration_time = now + clib_net_to_host_u32 (rr->ttl);
@@ -2317,7 +2359,7 @@ VLIB_CLI_COMMAND (dns_cache_add_del_command) =
};
/* *INDENT-ON* */
-#define DNS_FORMAT_TEST 0
+#define DNS_FORMAT_TEST 1
#if DNS_FORMAT_TEST > 0
#if 0
@@ -2454,7 +2496,6 @@ static u8 dns_reply_data_initializer[] = {
};
/* google.com */
-#else
static u8 dns_reply_data_initializer[] =
{ 0x0, 0x0, 0x81, 0x80, 0x0, 0x1, 0x0, 0xe, 0x0, 0x0, 0x0, 0x0, 0x6,
0x67, 0x6f, 0x6f, 0x67, 0x6c, 0x65, 0x3, 0x63, 0x6f, 0x6d, 0x0, 0x0, 0xff,
@@ -2487,6 +2528,21 @@ static u8 dns_reply_data_initializer[] =
0x57,
0x0, 0x9, 0x0, 0x14, 0x4, 0x61, 0x6c, 0x74, 0x31, 0xc0, 0x9b
};
+
+#else
+/* www.weatherlink.com */
+static u8 dns_reply_data_initializer[] = {
+ 0x00, 0x00, 0x81, 0x80, 0x00, 0x01, 0x00, 0x01,
+ 0x00, 0x00, 0x00, 0x00, 0x03, 0x77, 0x77, 0x77, 0x0b,
+ 0x77, 0x65, 0x61, 0x74, 0x68, 0x65, 0x72, 0x6c, 0x69,
+ 0x6e, 0x6b, 0x03, 0x63, 0x6f, 0x6d, 0x00, 0x00, 0xff,
+ 0x00, 0x01, 0xc0, 0x0c, 0x00, 0x05, 0x00, 0x01, 0x00,
+ 0x00, 0x0c, 0x9e, 0x00, 0x1f, 0x0e, 0x64, 0x33, 0x6b,
+ 0x72, 0x30, 0x67, 0x75, 0x62, 0x61, 0x31, 0x64, 0x76,
+ 0x77, 0x66, 0x0a, 0x63, 0x6c, 0x6f, 0x75, 0x64, 0x66,
+ 0x72, 0x6f, 0x6e, 0x74, 0x03, 0x6e, 0x65, 0x74, 0x00,
+};
+
#endif
static clib_error_t *
diff --git a/src/vnet/dns/dns.h b/src/vnet/dns/dns.h
index 1272e756d7c..f0edd8cf4ba 100644
--- a/src/vnet/dns/dns.h
+++ b/src/vnet/dns/dns.h
@@ -66,6 +66,7 @@ typedef struct
int retry_count;
int server_rotor;
int server_af;
+ int server_fails;
f64 retry_timer;
/** Cached dns response */
@@ -163,6 +164,13 @@ int
vnet_dns_resolve_name (dns_main_t * dm, u8 * name, dns_pending_request_t * t,
dns_cache_entry_t ** retp);
+void
+vnet_dns_send_dns6_request (dns_main_t * dm,
+ dns_cache_entry_t * ep, ip6_address_t * server);
+void
+vnet_dns_send_dns4_request (dns_main_t * dm,
+ dns_cache_entry_t * ep, ip4_address_t * server);
+
void vnet_send_dns4_reply (dns_main_t * dm, dns_pending_request_t * t,
dns_cache_entry_t * ep, vlib_buffer_t * b0);
diff --git a/src/vnet/dns/request_node.c b/src/vnet/dns/request_node.c
index f7446cce825..b91d2997dfb 100644
--- a/src/vnet/dns/request_node.c
+++ b/src/vnet/dns/request_node.c
@@ -208,7 +208,13 @@ dns46_request_inline (vlib_main_t * vm,
label0 = (u8 *) (d0 + 1);
+ /*
+ * vnet_dns_labels_to_name produces a non NULL terminated vector
+ * vnet_dns_resolve_name expects a C-string.
+ */
name0 = vnet_dns_labels_to_name (label0, (u8 *) d0, (u8 **) & q0);
+ vec_add1 (name0, 0);
+ _vec_len (name0) -= 1;
t0->request_type = DNS_PEER_PENDING_NAME_TO_IP;
diff --git a/src/vnet/dns/resolver_process.c b/src/vnet/dns/resolver_process.c
index 47d8a95ea16..5f43fada983 100644
--- a/src/vnet/dns/resolver_process.c
+++ b/src/vnet/dns/resolver_process.c
@@ -86,12 +86,69 @@ resolve_event (dns_main_t * dm, f64 now, u8 * reply)
vec_free (ep->dns_response);
/* Handle [sic] recursion AKA CNAME indirection */
- if (vnet_dns_cname_indirection_nolock (dm, pool_index, reply))
+ rv = vnet_dns_cname_indirection_nolock (dm, pool_index, reply);
+
+ /* CNAME found, further resolution pending, we're done here */
+ if (rv > 0)
+ {
+ dns_cache_unlock (dm);
+ return;
+ }
+ /* Server backfire: refused to answer, or sent zero replies */
+ if (rv < 0)
{
+ /* Try a different server */
+ if (ep->server_af /* ip6 */ )
+ {
+ if (0)
+ clib_warning ("Server %U failed to resolve '%s'",
+ format_ip6_address,
+ dm->ip6_name_servers + ep->server_rotor, ep->name);
+ /* Any more servers to try? */
+ if (ep->server_fails > 1 || vec_len (dm->ip6_name_servers) <= 1)
+ {
+ /* No, tell the client to go away */
+ goto reply;
+ }
+ ep->retry_count = 0;
+ ep->server_rotor++;
+ ep->server_fails++;
+ if (ep->server_rotor >= vec_len (dm->ip6_name_servers))
+ ep->server_rotor = 0;
+ if (0)
+ clib_warning ("Try server %U", format_ip6_address,
+ dm->ip6_name_servers + ep->server_rotor);
+ vnet_dns_send_dns6_request
+ (dm, ep, dm->ip6_name_servers + ep->server_rotor);
+ }
+ else
+ {
+ if (0)
+ clib_warning ("Server %U failed to resolve '%s'",
+ format_ip4_address,
+ dm->ip4_name_servers + ep->server_rotor, ep->name);
+
+ if (ep->server_fails > 1 || vec_len (dm->ip4_name_servers) <= 1)
+ {
+ /* No, tell the client to go away */
+ goto reply;
+ }
+ ep->retry_count = 0;
+ ep->server_rotor++;
+ ep->server_fails++;
+ if (ep->server_rotor >= vec_len (dm->ip4_name_servers))
+ ep->server_rotor = 0;
+ if (0)
+ clib_warning ("Try server %U", format_ip4_address,
+ dm->ip4_name_servers + ep->server_rotor);
+ vnet_dns_send_dns4_request
+ (dm, ep, dm->ip4_name_servers + ep->server_rotor);
+ }
dns_cache_unlock (dm);
return;
}
+reply:
/* Save the response */
ep->dns_response = reply;
/* Pick some sensible default. */