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/* SPDX-License-Identifier: LGPL-2.1-or-later */
#pragma once
#include "sd-event.h"
#include "in-addr-util.h"
typedef struct DnsTransaction DnsTransaction;
typedef struct DnsTransactionFinder DnsTransactionFinder;
typedef enum DnsTransactionState DnsTransactionState;
typedef enum DnsTransactionSource DnsTransactionSource;
#include "resolved-dns-answer.h"
#include "resolved-dns-dnssec.h"
#include "resolved-dns-packet.h"
#include "resolved-dns-question.h"
#include "resolved-dns-server.h"
enum DnsTransactionState {
DNS_TRANSACTION_NULL,
DNS_TRANSACTION_PENDING,
DNS_TRANSACTION_VALIDATING,
DNS_TRANSACTION_RCODE_FAILURE,
DNS_TRANSACTION_SUCCESS,
DNS_TRANSACTION_NO_SERVERS,
DNS_TRANSACTION_TIMEOUT,
DNS_TRANSACTION_ATTEMPTS_MAX_REACHED,
DNS_TRANSACTION_INVALID_REPLY,
DNS_TRANSACTION_ERRNO,
DNS_TRANSACTION_ABORTED,
DNS_TRANSACTION_DNSSEC_FAILED,
DNS_TRANSACTION_NO_TRUST_ANCHOR,
DNS_TRANSACTION_RR_TYPE_UNSUPPORTED,
DNS_TRANSACTION_NETWORK_DOWN,
DNS_TRANSACTION_NOT_FOUND, /* like NXDOMAIN, but when LLMNR/TCP connections fail */
DNS_TRANSACTION_NO_SOURCE, /* All suitable DnsTransactionSource turned off */
DNS_TRANSACTION_STUB_LOOP,
_DNS_TRANSACTION_STATE_MAX,
_DNS_TRANSACTION_STATE_INVALID = -EINVAL,
};
#define DNS_TRANSACTION_IS_LIVE(state) IN_SET((state), DNS_TRANSACTION_NULL, DNS_TRANSACTION_PENDING, DNS_TRANSACTION_VALIDATING)
enum DnsTransactionSource {
DNS_TRANSACTION_NETWORK,
DNS_TRANSACTION_CACHE,
DNS_TRANSACTION_ZONE,
DNS_TRANSACTION_TRUST_ANCHOR,
_DNS_TRANSACTION_SOURCE_MAX,
_DNS_TRANSACTION_SOURCE_INVALID = -EINVAL,
};
struct DnsTransaction {
DnsScope *scope;
DnsResourceKey *key; /* For regular lookups the RR key to look for */
DnsPacket *bypass; /* For bypass lookups the full original request packet */
uint64_t query_flags;
DnsPacket *sent, *received;
DnsAnswer *answer;
int answer_rcode;
DnssecResult answer_dnssec_result;
DnsTransactionSource answer_source;
uint32_t answer_nsec_ttl;
int answer_errno; /* if state is DNS_TRANSACTION_ERRNO */
DnsTransactionState state;
/* SD_RESOLVED_AUTHENTICATED here indicates whether the primary answer is authenticated, i.e. whether
* the RRs from answer which directly match the question are authenticated, or, if there are none,
* whether the NODATA or NXDOMAIN case is. It says nothing about additional RRs listed in the answer,
* however they have their own DNS_ANSWER_AUTHORIZED FLAGS. Note that this bit is defined different
* than the AD bit in DNS packets, as that covers more than just the actual primary answer. */
uint64_t answer_query_flags;
/* Contains DNSKEY, DS, SOA RRs we already verified and need
* to authenticate this reply */
DnsAnswer *validated_keys;
usec_t start_usec;
usec_t next_attempt_after;
sd_event_source *timeout_event_source;
unsigned n_attempts;
/* UDP connection logic, if we need it */
int dns_udp_fd;
sd_event_source *dns_udp_event_source;
/* TCP connection logic, if we need it */
DnsStream *stream;
/* The active server */
DnsServer *server;
/* The features of the DNS server at time of transaction start */
DnsServerFeatureLevel current_feature_level;
/* If we got SERVFAIL back, we retry the lookup, using a lower feature level than we used
* before. Similar, if we get NXDOMAIN in pure EDNS0 mode, we check in EDNS0-less mode before giving
* up (as mitigation for DVE-2018-0001). */
DnsServerFeatureLevel clamp_feature_level_servfail;
DnsServerFeatureLevel clamp_feature_level_nxdomain;
uint16_t id;
bool tried_stream:1;
bool initial_jitter_scheduled:1;
bool initial_jitter_elapsed:1;
bool probing:1;
/* Query candidates this transaction is referenced by and that
* shall be notified about this specific transaction
* completing. */
Set *notify_query_candidates, *notify_query_candidates_done;
/* Zone items this transaction is referenced by and that shall
* be notified about completion. */
Set *notify_zone_items, *notify_zone_items_done;
/* Other transactions that this transactions is referenced by
* and that shall be notified about completion. This is used
* when transactions want to validate their RRsets, but need
* another DNSKEY or DS RR to do so. */
Set *notify_transactions, *notify_transactions_done;
/* The opposite direction: the transactions this transaction
* created in order to request DNSKEY or DS RRs. */
Set *dnssec_transactions;
unsigned n_picked_servers;
unsigned block_gc;
/* Set when we're willing to let this transaction live beyond it's usefulness for the original query,
* for caching purposes. This blocks gc while there is still a chance we might still receive an
* answer. */
bool wait_for_answer;
LIST_FIELDS(DnsTransaction, transactions_by_scope);
LIST_FIELDS(DnsTransaction, transactions_by_stream);
LIST_FIELDS(DnsTransaction, transactions_by_key);
/* Note: fields should be ordered to minimize alignment gaps. Use pahole! */
};
int dns_transaction_new(DnsTransaction **ret, DnsScope *s, DnsResourceKey *key, DnsPacket *bypass, uint64_t flags);
DnsTransaction* dns_transaction_free(DnsTransaction *t);
DnsTransaction* dns_transaction_gc(DnsTransaction *t);
DEFINE_TRIVIAL_CLEANUP_FUNC(DnsTransaction*, dns_transaction_gc);
int dns_transaction_go(DnsTransaction *t);
void dns_transaction_process_reply(DnsTransaction *t, DnsPacket *p, bool encrypted);
void dns_transaction_complete(DnsTransaction *t, DnsTransactionState state);
void dns_transaction_notify(DnsTransaction *t, DnsTransaction *source);
int dns_transaction_validate_dnssec(DnsTransaction *t);
int dns_transaction_request_dnssec_keys(DnsTransaction *t);
static inline DnsResourceKey *dns_transaction_key(DnsTransaction *t) {
assert(t);
/* Return the lookup key of this transaction. Either takes the lookup key from the bypass packet if
* we are a bypass transaction. Or take the configured key for regular transactions. */
if (t->key)
return t->key;
assert(t->bypass);
return dns_question_first_key(t->bypass->question);
}
static inline uint64_t dns_transaction_source_to_query_flags(DnsTransactionSource s) {
switch (s) {
case DNS_TRANSACTION_NETWORK:
return SD_RESOLVED_FROM_NETWORK;
case DNS_TRANSACTION_CACHE:
return SD_RESOLVED_FROM_CACHE;
case DNS_TRANSACTION_ZONE:
return SD_RESOLVED_FROM_ZONE;
case DNS_TRANSACTION_TRUST_ANCHOR:
return SD_RESOLVED_FROM_TRUST_ANCHOR;
default:
return 0;
}
}
const char* dns_transaction_state_to_string(DnsTransactionState p) _const_;
DnsTransactionState dns_transaction_state_from_string(const char *s) _pure_;
const char* dns_transaction_source_to_string(DnsTransactionSource p) _const_;
DnsTransactionSource dns_transaction_source_from_string(const char *s) _pure_;
/* LLMNR Jitter interval, see RFC 4795 Section 7 */
#define LLMNR_JITTER_INTERVAL_USEC (100 * USEC_PER_MSEC)
/* mDNS probing interval, see RFC 6762 Section 8.1 */
#define MDNS_PROBING_INTERVAL_USEC (250 * USEC_PER_MSEC)
/* Maximum attempts to send DNS requests, across all DNS servers */
#define DNS_TRANSACTION_ATTEMPTS_MAX 24
/* Maximum attempts to send LLMNR requests, see RFC 4795 Section 2.7 */
#define LLMNR_TRANSACTION_ATTEMPTS_MAX 3
/* Maximum attempts to send MDNS requests, see RFC 6762 Section 8.1 */
#define MDNS_TRANSACTION_ATTEMPTS_MAX 3
#define TRANSACTION_ATTEMPTS_MAX(p) ((p) == DNS_PROTOCOL_LLMNR ? \
LLMNR_TRANSACTION_ATTEMPTS_MAX : \
(p) == DNS_PROTOCOL_MDNS ? \
MDNS_TRANSACTION_ATTEMPTS_MAX : \
DNS_TRANSACTION_ATTEMPTS_MAX)
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