diff options
Diffstat (limited to 'src/plugins/dns/resolver_process.c')
| -rw-r--r-- | src/plugins/dns/resolver_process.c | 381 |
1 files changed, 381 insertions, 0 deletions
diff --git a/src/plugins/dns/resolver_process.c b/src/plugins/dns/resolver_process.c new file mode 100644 index 00000000000..802da53cec5 --- /dev/null +++ b/src/plugins/dns/resolver_process.c @@ -0,0 +1,381 @@ +/* + * 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: + */ |