1/* Extended resolver state separate from struct __res_state.
2 Copyright (C) 2017-2020 Free Software Foundation, Inc.
3 This file is part of the GNU C Library.
4
5 The GNU C Library is free software; you can redistribute it and/or
6 modify it under the terms of the GNU Lesser General Public
7 License as published by the Free Software Foundation; either
8 version 2.1 of the License, or (at your option) any later version.
9
10 The GNU C Library is distributed in the hope that it will be useful,
11 but WITHOUT ANY WARRANTY; without even the implied warranty of
12 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
13 Lesser General Public License for more details.
14
15 You should have received a copy of the GNU Lesser General Public
16 License along with the GNU C Library; if not, see
17 <https://www.gnu.org/licenses/>. */
18
19#ifndef RESOLV_STATE_H
20#define RESOLV_STATE_H
21
22#include <netinet/in.h>
23#include <stdbool.h>
24#include <stddef.h>
25
26/* This type corresponds to members of the _res.sort_list array. */
27struct resolv_sortlist_entry
28{
29 struct in_addr addr;
30 uint32_t mask;
31};
32
33/* Extended resolver state associated with res_state objects. Client
34 code can reach this state through a struct resolv_context
35 object. */
36struct resolv_conf
37{
38 /* Reference counter. The object is deallocated once it reaches
39 zero. For internal use within resolv_conf only. */
40 size_t __refcount;
41
42 /* List of IPv4 and IPv6 name server addresses. */
43 const struct sockaddr **nameserver_list;
44 size_t nameserver_list_size;
45
46 /* The domain names forming the search list. */
47 const char *const *search_list;
48 size_t search_list_size;
49
50 /* IPv4 address preference rules. */
51 const struct resolv_sortlist_entry *sort_list;
52 size_t sort_list_size;
53
54 /* _res.options has type unsigned long, but we can only use 32 bits
55 for portability across all architectures. */
56 unsigned int options;
57 unsigned int retrans; /* Timeout. */
58 unsigned int retry; /* Number of times to retry. */
59 unsigned int ndots; /* Dots needed for initial non-search query. */
60};
61
62/* The functions below are for use by the res_init resolv.conf parser
63 and the struct resolv_context facility. */
64
65struct __res_state;
66struct file_change_detection;
67
68/* Read /etc/resolv.conf and return a configuration object, or NULL if
69 /etc/resolv.conf cannot be read due to memory allocation errors.
70 If PREINIT is not NULL, some configuration values are taken from
71 the struct __res_state object. If CHANGE is not null, file change
72 detection data is written to *CHANGE, based on the state of the
73 file after reading it. */
74struct resolv_conf *__resolv_conf_load (struct __res_state *preinit,
75 struct file_change_detection *change)
76 attribute_hidden __attribute__ ((warn_unused_result));
77
78/* Return a configuration object for the current /etc/resolv.conf
79 settings, or NULL on failure. The object is cached. */
80struct resolv_conf *__resolv_conf_get_current (void)
81 attribute_hidden __attribute__ ((warn_unused_result));
82
83/* Return the extended resolver state for *RESP, or NULL if it cannot
84 be determined. A call to this function must be paired with a call
85 to __resolv_conf_put. */
86struct resolv_conf *__resolv_conf_get (struct __res_state *) attribute_hidden;
87
88/* Converse of __resolv_conf_get. */
89void __resolv_conf_put (struct resolv_conf *) attribute_hidden;
90
91/* Allocate a new struct resolv_conf object and copy the
92 pre-configured values from *INIT. Return NULL on allocation
93 failure. The object must be deallocated using
94 __resolv_conf_put. */
95struct resolv_conf *__resolv_conf_allocate (const struct resolv_conf *init)
96 attribute_hidden __attribute__ ((nonnull (1), warn_unused_result));
97
98/* Associate an existing extended resolver state with *RESP. Return
99 false on allocation failure. In addition, update *RESP with the
100 overlapping non-extended resolver state. */
101bool __resolv_conf_attach (struct __res_state *, struct resolv_conf *)
102 attribute_hidden;
103
104/* Detach the extended resolver state from *RESP. */
105void __resolv_conf_detach (struct __res_state *resp) attribute_hidden;
106
107#endif /* RESOLV_STATE_H */
108