1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
|
/* 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;
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)
|
