src/resolve/dns-type.c

   1 /*-*- Mode: C; c-basic-offset: 8; indent-tabs-mode: nil -*-*/
   2
   3 /***
   4   This file is part of systemd.
   5
   6   Copyright 2014 Zbigniew Jędrzejewski-Szmek
   7
   8   systemd is free software; you can redistribute it and/or modify it
   9   under the terms of the GNU Lesser General Public License as published by
  10   the Free Software Foundation; either version 2.1 of the License, or
  11   (at your option) any later version.
  12
  13   systemd is distributed in the hope that it will be useful, but
  14   WITHOUT ANY WARRANTY; without even the implied warranty of
  15   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
  16   Lesser General Public License for more details.
  17
  18   You should have received a copy of the GNU Lesser General Public License
  19   along with systemd; If not, see <http://www.gnu.org/licenses/>.
  20 ***/
  21
  22 #include "dns-type.h"
  23 #include "string-util.h"
  24
  25 typedef const struct {
  26         uint16_t type;
  27         const char *name;
  28 } dns_type;
  29
  30 static const struct dns_type_name *
  31 lookup_dns_type (register const char *str, register unsigned int len);
  32
  33 #include "dns_type-from-name.h"
  34 #include "dns_type-to-name.h"
  35
  36 int dns_type_from_string(const char *s) {
  37         const struct dns_type_name *sc;
  38
  39         assert(s);
  40
  41         sc = lookup_dns_type(s, strlen(s));
  42         if (!sc)
  43                 return _DNS_TYPE_INVALID;
  44
  45         return sc->id;
  46 }
  47
  48 bool dns_type_is_pseudo(uint16_t type) {
  49
  50         /* Checks whether the specified type is a "pseudo-type". What
  51          * a "pseudo-type" precisely is, is defined only very weakly,
  52          * but apparently entails all RR types that are not actually
  53          * stored as RRs on the server and should hence also not be
  54          * cached. We use this list primarily to validate NSEC type
  55          * bitfields, and to verify what to cache. */
  56
  57         return IN_SET(type,
  58                       0, /* A Pseudo RR type, according to RFC 2931 */
  59                       DNS_TYPE_ANY,
  60                       DNS_TYPE_AXFR,
  61                       DNS_TYPE_IXFR,
  62                       DNS_TYPE_OPT,
  63                       DNS_TYPE_TSIG,
  64                       DNS_TYPE_TKEY
  65         );
  66 }
  67
  68 bool dns_class_is_pseudo(uint16_t class) {
  69         return class == DNS_TYPE_ANY;
  70 }
  71
  72 bool dns_type_is_valid_query(uint16_t type) {
  73
  74         /* The types valid as questions in packets */
  75
  76         return !IN_SET(type,
  77                        0,
  78                        DNS_TYPE_OPT,
  79                        DNS_TYPE_TSIG,
  80                        DNS_TYPE_TKEY);
  81 }
  82
  83 bool dns_type_is_valid_rr(uint16_t type) {
  84
  85         /* The types valid as RR in packets (but not necessarily
  86          * stored on servers). */
  87
  88         return !IN_SET(type,
  89                        DNS_TYPE_ANY,
  90                        DNS_TYPE_AXFR,
  91                        DNS_TYPE_IXFR);
  92 }
  93
  94 bool dns_class_is_valid_rr(uint16_t class) {
  95         return class != DNS_CLASS_ANY;
  96 }
  97
  98 bool dns_type_may_redirect(uint16_t type) {
  99         /* The following record types should never be redirected using
 100          * CNAME/DNAME RRs. See
 101          * <https://tools.ietf.org/html/rfc4035#section-2.5>. */
 102
 103         if (dns_type_is_pseudo(type))
 104                 return false;
 105
 106         return !IN_SET(type,
 107                        DNS_TYPE_CNAME,
 108                        DNS_TYPE_DNAME,
 109                        DNS_TYPE_NSEC3,
 110                        DNS_TYPE_NSEC,
 111                        DNS_TYPE_RRSIG,
 112                        DNS_TYPE_NXT,
 113                        DNS_TYPE_SIG,
 114                        DNS_TYPE_KEY);
 115 }
 116
 117 const char *dns_class_to_string(uint16_t class) {
 118
 119         switch (class) {
 120
 121         case DNS_CLASS_IN:
 122                 return "IN";
 123
 124         case DNS_CLASS_ANY:
 125                 return "ANY";
 126         }
 127
 128         return NULL;
 129 }
 130
 131 int dns_class_from_string(const char *s) {
 132
 133         if (!s)
 134                 return _DNS_CLASS_INVALID;
 135
 136         if (strcaseeq(s, "IN"))
 137                 return DNS_CLASS_IN;
 138         else if (strcaseeq(s, "ANY"))
 139                 return DNS_CLASS_ANY;
 140
 141         return _DNS_CLASS_INVALID;
 142 }