/* * 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.api_enum.h> #include <dns/dns.api_types.h> #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, 10); 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, 11); 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: */