src/resolve/resolved-dns-packet.h

   1 /*-*- Mode: C; c-basic-offset: 8; indent-tabs-mode: nil -*-*/
   2
   3 #pragma once
   4
   5 /***
   6   This file is part of systemd.
   7
   8   Copyright 2014 Lennart Poettering
   9
  10   systemd is free software; you can redistribute it and/or modify it
  11   under the terms of the GNU Lesser General Public License as published by
  12   the Free Software Foundation; either version 2.1 of the License, or
  13   (at your option) any later version.
  14
  15   systemd is distributed in the hope that it will be useful, but
  16   WITHOUT ANY WARRANTY; without even the implied warranty of
  17   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
  18   Lesser General Public License for more details.
  19
  20   You should have received a copy of the GNU Lesser General Public License
  21   along with systemd; If not, see <http://www.gnu.org/licenses/>.
  22  ***/
  23
  24 #include <inttypes.h>
  25
  26 #include "macro.h"
  27 #include "sparse-endian.h"
  28 #include "hashmap.h"
  29 #include "in-addr-util.h"
  30
  31 typedef struct DnsPacketHeader DnsPacketHeader;
  32 typedef struct DnsPacket DnsPacket;
  33
  34 #include "resolved-dns-rr.h"
  35 #include "resolved-dns-question.h"
  36 #include "resolved-dns-answer.h"
  37
  38 typedef enum DnsProtocol {
  39         DNS_PROTOCOL_DNS,
  40         DNS_PROTOCOL_MDNS,
  41         DNS_PROTOCOL_LLMNR,
  42         _DNS_PROTOCOL_MAX,
  43         _DNS_PROTOCOL_INVALID = -1
  44 } DnsProtocol;
  45
  46 struct DnsPacketHeader {
  47         uint16_t id;
  48         be16_t flags;
  49         be16_t qdcount;
  50         be16_t ancount;
  51         be16_t nscount;
  52         be16_t arcount;
  53 };
  54
  55 #define DNS_PACKET_HEADER_SIZE sizeof(DnsPacketHeader)
  56
  57 /* The various DNS protocols deviate in how large a packet can grow,
  58    but the TCP transport has a 16bit size field, hence that appears to
  59    be the absolute maximum. */
  60 #define DNS_PACKET_SIZE_MAX 0xFFFF
  61
  62 /* RFC 1035 say 512 is the maximum, for classic unicast DNS */
  63 #define DNS_PACKET_UNICAST_SIZE_MAX 512
  64
  65 #define DNS_PACKET_SIZE_START 512
  66
  67 struct DnsPacket {
  68         int n_ref;
  69         DnsProtocol protocol;
  70         size_t size, allocated, rindex;
  71         void *_data; /* don't access directly, use DNS_PACKET_DATA()! */
  72         Hashmap *names; /* For name compression */
  73
  74         /* Parsed data */
  75         DnsQuestion *question;
  76         DnsAnswer *answer;
  77
  78         /* Packet reception meta data */
  79         int ifindex;
  80         int family, ipproto;
  81         union in_addr_union sender, destination;
  82         uint16_t sender_port, destination_port;
  83         uint32_t ttl;
  84 };
  85
  86 static inline uint8_t* DNS_PACKET_DATA(DnsPacket *p) {
  87         if (_unlikely_(!p))
  88                 return NULL;
  89
  90         if (p->_data)
  91                 return p->_data;
  92
  93         return ((uint8_t*) p) + ALIGN(sizeof(DnsPacket));
  94 }
  95
  96 #define DNS_PACKET_HEADER(p) ((DnsPacketHeader*) DNS_PACKET_DATA(p))
  97 #define DNS_PACKET_ID(p) DNS_PACKET_HEADER(p)->id
  98 #define DNS_PACKET_QR(p) ((be16toh(DNS_PACKET_HEADER(p)->flags) >> 15) & 1)
  99 #define DNS_PACKET_OPCODE(p) ((be16toh(DNS_PACKET_HEADER(p)->flags) >> 11) & 15)
 100 #define DNS_PACKET_RCODE(p) (be16toh(DNS_PACKET_HEADER(p)->flags) & 15)
 101 #define DNS_PACKET_TC(p) ((be16toh(DNS_PACKET_HEADER(p)->flags) >> 9) & 1)
 102 #define DNS_PACKET_C(p) ((be16toh(DNS_PACKET_HEADER(p)->flags) >> 10) & 1)
 103 #define DNS_PACKET_T(p) ((be16toh(DNS_PACKET_HEADER(p)->flags) >> 8) & 1)
 104 #define DNS_PACKET_QDCOUNT(p) be16toh(DNS_PACKET_HEADER(p)->qdcount)
 105 #define DNS_PACKET_ANCOUNT(p) be16toh(DNS_PACKET_HEADER(p)->ancount)
 106 #define DNS_PACKET_NSCOUNT(p) be16toh(DNS_PACKET_HEADER(p)->nscount)
 107 #define DNS_PACKET_ARCOUNT(p) be16toh(DNS_PACKET_HEADER(p)->arcount)
 108
 109 #define DNS_PACKET_MAKE_FLAGS(qr, opcode, aa, tc, rd, ra, ad, cd, rcode) \
 110         (((uint16_t) !!qr << 15) |  \
 111          ((uint16_t) (opcode & 15) << 11) | \
 112          ((uint16_t) !!aa << 10) | \
 113          ((uint16_t) !!tc << 9) | \
 114          ((uint16_t) !!rd << 8) | \
 115          ((uint16_t) !!ra << 7) | \
 116          ((uint16_t) !!ad << 5) | \
 117          ((uint16_t) !!cd << 4) | \
 118          ((uint16_t) (rcode & 15)))
 119
 120 static inline unsigned DNS_PACKET_RRCOUNT(DnsPacket *p) {
 121         return
 122                 (unsigned) DNS_PACKET_ANCOUNT(p) +
 123                 (unsigned) DNS_PACKET_NSCOUNT(p) +
 124                 (unsigned) DNS_PACKET_ARCOUNT(p);
 125 }
 126
 127 int dns_packet_new(DnsPacket **p, DnsProtocol protocol, size_t mtu);
 128 int dns_packet_new_query(DnsPacket **p, DnsProtocol protocol, size_t mtu);
 129
 130 DnsPacket *dns_packet_ref(DnsPacket *p);
 131 DnsPacket *dns_packet_unref(DnsPacket *p);
 132
 133 DEFINE_TRIVIAL_CLEANUP_FUNC(DnsPacket*, dns_packet_unref);
 134
 135 int dns_packet_validate(DnsPacket *p);
 136 int dns_packet_validate_reply(DnsPacket *p);
 137 int dns_packet_validate_query(DnsPacket *p);
 138
 139 int dns_packet_append_blob(DnsPacket *p, const void *d, size_t sz, size_t *start);
 140 int dns_packet_append_uint8(DnsPacket *p, uint8_t v, size_t *start);
 141 int dns_packet_append_uint16(DnsPacket *p, uint16_t v, size_t *start);
 142 int dns_packet_append_uint32(DnsPacket *p, uint32_t v, size_t *start);
 143 int dns_packet_append_string(DnsPacket *p, const char *s, size_t *start);
 144 int dns_packet_append_label(DnsPacket *p, const char *s, size_t l, size_t *start);
 145 int dns_packet_append_name(DnsPacket *p, const char *name,
 146                            bool allow_compression, size_t *start);
 147 int dns_packet_append_key(DnsPacket *p, const DnsResourceKey *key, size_t *start);
 148 int dns_packet_append_rr(DnsPacket *p, const DnsResourceRecord *rr, size_t *start);
 149
 150 int dns_packet_read(DnsPacket *p, size_t sz, const void **ret, size_t *start);
 151 int dns_packet_read_blob(DnsPacket *p, void *d, size_t sz, size_t *start);
 152 int dns_packet_read_uint8(DnsPacket *p, uint8_t *ret, size_t *start);
 153 int dns_packet_read_uint16(DnsPacket *p, uint16_t *ret, size_t *start);
 154 int dns_packet_read_uint32(DnsPacket *p, uint32_t *ret, size_t *start);
 155 int dns_packet_read_string(DnsPacket *p, char **ret, size_t *start);
 156 int dns_packet_read_name(DnsPacket *p, char **ret,
 157                          bool allow_compression, size_t *start);
 158 int dns_packet_read_key(DnsPacket *p, DnsResourceKey **ret, size_t *start);
 159 int dns_packet_read_rr(DnsPacket *p, DnsResourceRecord **ret, size_t *start);
 160
 161 void dns_packet_rewind(DnsPacket *p, size_t idx);
 162
 163 int dns_packet_skip_question(DnsPacket *p);
 164 int dns_packet_extract(DnsPacket *p);
 165
 166 enum {
 167         DNS_RCODE_SUCCESS = 0,
 168         DNS_RCODE_FORMERR = 1,
 169         DNS_RCODE_SERVFAIL = 2,
 170         DNS_RCODE_NXDOMAIN = 3,
 171         DNS_RCODE_NOTIMP = 4,
 172         DNS_RCODE_REFUSED = 5,
 173         DNS_RCODE_YXDOMAIN = 6,
 174         DNS_RCODE_YXRRSET = 7,
 175         DNS_RCODE_NXRRSET = 8,
 176         DNS_RCODE_NOTAUTH = 9,
 177         DNS_RCODE_NOTZONE = 10,
 178         DNS_RCODE_BADVERS = 16,
 179         DNS_RCODE_BADSIG = 16, /* duplicate value! */
 180         DNS_RCODE_BADKEY = 17,
 181         DNS_RCODE_BADTIME = 18,
 182         DNS_RCODE_BADMODE = 19,
 183         DNS_RCODE_BADNAME = 20,
 184         DNS_RCODE_BADALG = 21,
 185         DNS_RCODE_BADTRUNC = 22,
 186         _DNS_RCODE_MAX_DEFINED
 187 };
 188
 189 const char* dns_rcode_to_string(int i) _const_;
 190 int dns_rcode_from_string(const char *s) _pure_;
 191
 192 const char* dns_protocol_to_string(DnsProtocol p) _const_;
 193 DnsProtocol dns_protocol_from_string(const char *s) _pure_;
 194
 195 #define LLMNR_MULTICAST_IPV4_ADDRESS ((struct in_addr) { .s_addr = htobe32(224U << 24 | 252U) })
 196 #define LLMNR_MULTICAST_IPV6_ADDRESS ((struct in6_addr) { .s6_addr = { 0xFF, 0x02, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x01, 0x00, 0x03 } })
 197
 198 #define DNSKEY_FLAG_ZONE_KEY (1u << 8)
 199 #define DNSKEY_FLAG_SEP      (1u << 0)
 200
 201 static inline uint16_t dnskey_to_flags(const DnsResourceRecord *rr) {
 202         return (rr->dnskey.zone_key_flag * DNSKEY_FLAG_ZONE_KEY |
 203                 rr->dnskey.sep_flag * DNSKEY_FLAG_SEP);
 204 }
 205
 206 /* http://tools.ietf.org/html/rfc4034#appendix-A.1 */
 207 enum {
 208         DNSSEC_ALGORITHM_RSAMD5 = 1,
 209         DNSSEC_ALGORITHM_DH,
 210         DNSSEC_ALGORITHM_DSA,
 211         DNSSEC_ALGORITHM_ECC,
 212         DNSSEC_ALGORITHM_RSASHA1,
 213         DNSSEC_ALGORITHM_INDIRECT = 252,
 214         DNSSEC_ALGORITHM_PRIVATEDNS,
 215         DNSSEC_ALGORITHM_PRIVATEOID,
 216         _DNSSEC_ALGORITHM_MAX_DEFINED
 217 };
 218
 219 const char* dnssec_algorithm_to_string(int i) _const_;
 220 int dnssec_algorithm_from_string(const char *s) _pure_;