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-rw-r--r--src/plugins/dns/resolver_process.c381
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diff --git a/src/plugins/dns/resolver_process.c b/src/plugins/dns/resolver_process.c
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+/*
+ * Copyright (c) 2017 Cisco and/or its affiliates.
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at:
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include <dns/dns.h>
+#include <vlibapi/api.h>
+#include <vlibmemory/api.h>
+
+#include <vlib/vlib.h>
+#include <vnet/vnet.h>
+
+/* define message IDs */
+#include <dns/dns_msg_enum.h>
+
+#define vl_typedefs /* define message structures */
+#include <dns/dns_all_api_h.h>
+#undef vl_typedefs
+
+#define vl_endianfun /* define message structures */
+#include <dns/dns_all_api_h.h>
+#undef vl_endianfun
+
+/* instantiate all the print functions we know about */
+#define vl_print(handle, ...) vlib_cli_output (handle, __VA_ARGS__)
+#define vl_printfun
+#include <dns/dns_all_api_h.h>
+#undef vl_printfun
+
+#include <vlibapi/api_helper_macros.h>
+
+int
+vnet_dns_response_to_reply (u8 * response,
+ vl_api_dns_resolve_name_reply_t * rmp,
+ u32 * min_ttlp);
+int
+vnet_dns_response_to_name (u8 * response,
+ vl_api_dns_resolve_ip_reply_t * rmp,
+ u32 * min_ttlp);
+
+static void
+resolve_event (dns_main_t * dm, f64 now, u8 * reply)
+{
+ vlib_main_t *vm = dm->vlib_main;
+ dns_pending_request_t *pr;
+ dns_header_t *d;
+ u32 pool_index;
+ dns_cache_entry_t *ep;
+ u32 min_ttl;
+ u16 flags;
+ u16 rcode;
+ int i;
+ int entry_was_valid;
+ int remove_count;
+ int rv = 0;
+
+ d = (dns_header_t *) reply;
+ flags = clib_net_to_host_u16 (d->flags);
+ rcode = flags & DNS_RCODE_MASK;
+
+ /* $$$ u16 limits cache to 65K entries, fix later multiple dst ports */
+ pool_index = clib_net_to_host_u16 (d->id);
+ dns_cache_lock (dm);
+
+ if (pool_is_free_index (dm->entries, pool_index))
+ {
+ vec_free (reply);
+ if (0)
+ clib_warning ("pool index %d is free", pool_index);
+ vlib_node_increment_counter (vm, dns46_reply_node.index,
+ DNS46_REPLY_ERROR_NO_ELT, 1);
+ dns_cache_unlock (dm);
+ return;
+ }
+
+ ep = pool_elt_at_index (dm->entries, pool_index);
+
+ if (ep->dns_response)
+ vec_free (ep->dns_response);
+
+ /* Handle [sic] recursion AKA CNAME indirection */
+ 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 a sensible default cache entry expiration time.
+ * We don't play the 10-second timeout game.
+ */
+ ep->expiration_time = now + 600.0;
+
+ if (0)
+ clib_warning ("resolving '%s', was %s valid",
+ ep->name, (ep->flags & DNS_CACHE_ENTRY_FLAG_VALID) ?
+ "already" : "not");
+ /*
+ * The world is a mess. A single DNS request sent to e.g. 8.8.8.8
+ * may yield multiple, subtly different responses - all with the same
+ * DNS protocol-level ID.
+ *
+ * Last response wins in terms of what ends up in the cache.
+ * First response wins in terms of the response sent to the client.
+ */
+
+ /* Strong hint that we may not find a pending resolution entry */
+ entry_was_valid = (ep->flags & DNS_CACHE_ENTRY_FLAG_VALID) ? 1 : 0;
+
+ if (vec_len (ep->dns_response))
+ ep->flags |= DNS_CACHE_ENTRY_FLAG_VALID;
+
+ /* Most likely, send 1 message */
+ for (i = 0; i < vec_len (ep->pending_requests); i++)
+ {
+ vl_api_registration_t *regp;
+
+ pr = vec_elt_at_index (ep->pending_requests, i);
+
+ switch (pr->request_type)
+ {
+ case DNS_API_PENDING_NAME_TO_IP:
+ {
+ vl_api_dns_resolve_name_reply_t *rmp;
+ regp = vl_api_client_index_to_registration (pr->client_index);
+ if (regp == 0)
+ continue;
+
+ rmp = vl_msg_api_alloc (sizeof (*rmp));
+ rmp->_vl_msg_id =
+ clib_host_to_net_u16 (VL_API_DNS_RESOLVE_NAME_REPLY
+ + dm->msg_id_base);
+ rmp->context = pr->client_context;
+ min_ttl = ~0;
+ rv = vnet_dns_response_to_reply (ep->dns_response, rmp, &min_ttl);
+ if (min_ttl != ~0)
+ ep->expiration_time = now + min_ttl;
+ rmp->retval = clib_host_to_net_u32 (rv);
+ vl_api_send_msg (regp, (u8 *) rmp);
+ }
+ break;
+
+ case DNS_API_PENDING_IP_TO_NAME:
+ {
+ vl_api_dns_resolve_ip_reply_t *rmp;
+
+ regp = vl_api_client_index_to_registration (pr->client_index);
+ if (regp == 0)
+ continue;
+
+ rmp = vl_msg_api_alloc (sizeof (*rmp));
+ rmp->_vl_msg_id =
+ clib_host_to_net_u16 (VL_API_DNS_RESOLVE_IP_REPLY
+ + dm->msg_id_base);
+ rmp->context = pr->client_context;
+ min_ttl = ~0;
+ rv = vnet_dns_response_to_name (ep->dns_response, rmp, &min_ttl);
+ if (min_ttl != ~0)
+ ep->expiration_time = now + min_ttl;
+ rmp->retval = clib_host_to_net_u32 (rv);
+ vl_api_send_msg (regp, (u8 *) rmp);
+ }
+ break;
+
+ case DNS_PEER_PENDING_IP_TO_NAME:
+ case DNS_PEER_PENDING_NAME_TO_IP:
+ if (pr->is_ip6)
+ vnet_send_dns6_reply (dm, pr, ep, 0 /* allocate a buffer */ );
+ else
+ vnet_send_dns4_reply (dm, pr, ep, 0 /* allocate a buffer */ );
+ break;
+ default:
+ clib_warning ("request type %d unknown", pr->request_type);
+ break;
+ }
+ }
+ vec_free (ep->pending_requests);
+
+ remove_count = 0;
+ for (i = 0; i < vec_len (dm->unresolved_entries); i++)
+ {
+ if (dm->unresolved_entries[i] == pool_index)
+ {
+ vec_delete (dm->unresolved_entries, 1, i);
+ remove_count++;
+ i--;
+ }
+ }
+ /* See multiple response comment above... */
+ if (remove_count == 0)
+ {
+ u32 error_code = entry_was_valid ? DNS46_REPLY_ERROR_MULTIPLE_REPLY :
+ DNS46_REPLY_ERROR_NO_UNRESOLVED_ENTRY;
+
+ vlib_node_increment_counter (vm, dns46_reply_node.index, error_code, 1);
+ dns_cache_unlock (dm);
+ return;
+ }
+
+ /* Deal with bogus names, server issues, etc. */
+ switch (rcode)
+ {
+ default:
+ case DNS_RCODE_NO_ERROR:
+ break;
+
+ case DNS_RCODE_SERVER_FAILURE:
+ case DNS_RCODE_NOT_IMPLEMENTED:
+ case DNS_RCODE_REFUSED:
+ if (ep->server_af == 0)
+ clib_warning ("name server %U can't resolve '%s'",
+ format_ip4_address,
+ dm->ip4_name_servers + ep->server_rotor, ep->name);
+ else
+ clib_warning ("name server %U can't resolve '%s'",
+ format_ip6_address,
+ dm->ip6_name_servers + ep->server_rotor, ep->name);
+ /* FALLTHROUGH */
+ case DNS_RCODE_NAME_ERROR:
+ case DNS_RCODE_FORMAT_ERROR:
+ /* remove trash from the cache... */
+ vnet_dns_delete_entry_by_index_nolock (dm, ep - dm->entries);
+ break;
+ }
+
+
+ dns_cache_unlock (dm);
+ return;
+}
+
+static void
+retry_scan (dns_main_t * dm, f64 now)
+{
+ int i;
+ dns_cache_entry_t *ep;
+
+ for (i = 0; i < vec_len (dm->unresolved_entries); i++)
+ {
+ dns_cache_lock (dm);
+ ep = pool_elt_at_index (dm->entries, dm->unresolved_entries[i]);
+
+ ASSERT ((ep->flags & DNS_CACHE_ENTRY_FLAG_VALID) == 0);
+ vnet_send_dns_request (dm, ep);
+ dns_cache_unlock (dm);
+ }
+}
+
+static uword
+dns_resolver_process (vlib_main_t * vm,
+ vlib_node_runtime_t * rt, vlib_frame_t * f)
+{
+ dns_main_t *dm = &dns_main;
+ f64 now;
+ f64 timeout = 1000.0;
+ uword *event_data = 0;
+ uword event_type;
+ int i;
+
+ while (1)
+ {
+ vlib_process_wait_for_event_or_clock (vm, timeout);
+
+ now = vlib_time_now (vm);
+
+ event_type = vlib_process_get_events (vm, (uword **) & event_data);
+
+ switch (event_type)
+ {
+ /* Send one of these when a resolution is pending */
+ case DNS_RESOLVER_EVENT_PENDING:
+ timeout = 2.0;
+ break;
+
+ case DNS_RESOLVER_EVENT_RESOLVED:
+ for (i = 0; i < vec_len (event_data); i++)
+ resolve_event (dm, now, (u8 *) event_data[i]);
+ break;
+
+ case ~0: /* timeout */
+ retry_scan (dm, now);
+ break;
+ }
+ vec_reset_length (event_data);
+
+ /* No work? Back to slow timeout mode... */
+ if (vec_len (dm->unresolved_entries) == 0)
+ timeout = 1000.0;
+ }
+ return 0; /* or not */
+}
+
+void
+vnet_dns_create_resolver_process (dns_main_t * dm)
+{
+ /* Already created the resolver process? */
+ if (dm->resolver_process_node_index > 0)
+ return;
+
+ /* No, create it now and make a note of the node index */
+ dm->resolver_process_node_index = vlib_process_create
+ (dm->vlib_main, "dns-resolver-process",
+ dns_resolver_process, 16 /* log2_n_stack_bytes */ );
+}
+
+/*
+ * fd.io coding-style-patch-verification: ON
+ *
+ * Local Variables:
+ * eval: (c-set-style "gnu")
+ * End:
+ */