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  */
21 enum 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  */
28 enum 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  */
36 enum 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  */
45 enum 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  */
58 enum 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  */
73 struct 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  */
84 struct 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  */
97 struct 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  */
112 struct 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