1/* SPDX-License-Identifier: GPL-2.0+ WITH Linux-syscall-note */
2/* DNS resolver interface definitions.
3 *
4 * Copyright (C) 2018 Red Hat, Inc. All Rights Reserved.
5 * Written by David Howells (dhowells@redhat.com)
6 *
7 * This program is free software; you can redistribute it and/or
8 * modify it under the terms of the GNU General Public Licence
9 * as published by the Free Software Foundation; either version
10 * 2 of the Licence, or (at your option) any later version.
11 */
12
13#ifndef _UAPI_LINUX_DNS_RESOLVER_H
14#define _UAPI_LINUX_DNS_RESOLVER_H
15
16#include <linux/types.h>
17
18/*
19 * Type of payload.
20 */
21enum dns_payload_content_type {
22 DNS_PAYLOAD_IS_SERVER_LIST = 0, /* List of servers, requested by srv=1 */
23};
24
25/*
26 * Type of address that might be found in an address record.
27 */
28enum dns_payload_address_type {
29 DNS_ADDRESS_IS_IPV4 = 0, /* 4-byte AF_INET address */
30 DNS_ADDRESS_IS_IPV6 = 1, /* 16-byte AF_INET6 address */
31};
32
33/*
34 * Type of protocol used to access a server.
35 */
36enum dns_payload_protocol_type {
37 DNS_SERVER_PROTOCOL_UNSPECIFIED = 0,
38 DNS_SERVER_PROTOCOL_UDP = 1, /* Use UDP to talk to the server */
39 DNS_SERVER_PROTOCOL_TCP = 2, /* Use TCP to talk to the server */
40};
41
42/*
43 * Source of record included in DNS resolver payload.
44 */
45enum dns_record_source {
46 DNS_RECORD_UNAVAILABLE = 0, /* No source available (empty record) */
47 DNS_RECORD_FROM_CONFIG = 1, /* From local configuration data */
48 DNS_RECORD_FROM_DNS_A = 2, /* From DNS A or AAAA record */
49 DNS_RECORD_FROM_DNS_AFSDB = 3, /* From DNS AFSDB record */
50 DNS_RECORD_FROM_DNS_SRV = 4, /* From DNS SRV record */
51 DNS_RECORD_FROM_NSS = 5, /* From NSS */
52 NR__dns_record_source
53};
54
55/*
56 * Status of record included in DNS resolver payload.
57 */
58enum dns_lookup_status {
59 DNS_LOOKUP_NOT_DONE = 0, /* No lookup has been made */
60 DNS_LOOKUP_GOOD = 1, /* Good records obtained */
61 DNS_LOOKUP_GOOD_WITH_BAD = 2, /* Good records, some decoding errors */
62 DNS_LOOKUP_BAD = 3, /* Couldn't decode results */
63 DNS_LOOKUP_GOT_NOT_FOUND = 4, /* Got a "Not Found" result */
64 DNS_LOOKUP_GOT_LOCAL_FAILURE = 5, /* Local failure during lookup */
65 DNS_LOOKUP_GOT_TEMP_FAILURE = 6, /* Temporary failure during lookup */
66 DNS_LOOKUP_GOT_NS_FAILURE = 7, /* Name server failure */
67 NR__dns_lookup_status
68};
69
70/*
71 * Header at the beginning of binary format payload.
72 */
73struct dns_payload_header {
74 __u8 zero; /* Zero byte: marks this as not being text */
75 __u8 content; /* enum dns_payload_content_type */
76 __u8 version; /* Encoding version */
77} __packed;
78
79/*
80 * Header at the beginning of a V1 server list. This is followed directly by
81 * the server records. Each server records begins with a struct of type
82 * dns_server_list_v1_server.
83 */
84struct dns_server_list_v1_header {
85 struct dns_payload_header hdr;
86 __u8 source; /* enum dns_record_source */
87 __u8 status; /* enum dns_lookup_status */
88 __u8 nr_servers; /* Number of server records following this */
89} __packed;
90
91/*
92 * Header at the beginning of each V1 server record. This is followed by the
93 * characters of the name with no NUL-terminator, followed by the address
94 * records for that server. Each address record begins with a struct of type
95 * struct dns_server_list_v1_address.
96 */
97struct dns_server_list_v1_server {
98 __u16 name_len; /* Length of name (LE) */
99 __u16 priority; /* Priority (as SRV record) (LE) */
100 __u16 weight; /* Weight (as SRV record) (LE) */
101 __u16 port; /* UDP/TCP port number (LE) */
102 __u8 source; /* enum dns_record_source */
103 __u8 status; /* enum dns_lookup_status */
104 __u8 protocol; /* enum dns_payload_protocol_type */
105 __u8 nr_addrs;
106} __packed;
107
108/*
109 * Header at the beginning of each V1 address record. This is followed by the
110 * bytes of the address, 4 for IPV4 and 16 for IPV6.
111 */
112struct dns_server_list_v1_address {
113 __u8 address_type; /* enum dns_payload_address_type */
114} __packed;
115
116#endif /* _UAPI_LINUX_DNS_RESOLVER_H */
117