include/uapi/linux/dns_resolver.h

   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 */