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 typedef struct DnsPacketHeader DnsPacketHeader;
  25 typedef struct DnsPacket DnsPacket;
  26
  27 #include <inttypes.h>
  28
  29 #include "macro.h"
  30 #include "sparse-endian.h"
  31 #include "hashmap.h"
  32 #include "resolved-dns-rr.h"
  33
  34 typedef enum DnsProtocol {
  35         DNS_PROTOCOL_DNS,
  36         DNS_PROTOCOL_MDNS,
  37         DNS_PROTOCOL_LLMNR,
  38         _DNS_PROTOCOL_MAX,
  39         _DNS_PROTOCOL_INVALID = -1
  40 } DnsProtocol;
  41
  42 struct DnsPacketHeader {
  43         uint16_t id;
  44         be16_t flags;
  45         be16_t qdcount;
  46         be16_t ancount;
  47         be16_t nscount;
  48         be16_t arcount;
  49 };
  50
  51 #define DNS_PACKET_HEADER_SIZE sizeof(DnsPacketHeader)
  52
  53 /* The various DNS protocols deviate in how large a packet can grow,
  54    but the TCP transport has a 16bit size field, hence that appears to
  55    be the absolute maximum. */
  56 #define DNS_PACKET_SIZE_MAX 0xFFFF
  57
  58 /* RFC 1035 say 512 is the maximum, for classic unicast DNS */
  59 #define DNS_PACKET_UNICAST_SIZE_MAX 512
  60
  61 #define DNS_PACKET_SIZE_START 512
  62
  63 struct DnsPacket {
  64         int n_ref;
  65         DnsProtocol protocol;
  66         size_t size, allocated, rindex;
  67         void *data;
  68         Hashmap *names; /* For name compression */
  69         DnsResourceRecord **rrs;
  70
  71         /* Packet reception meta data */
  72         int ifindex;
  73         unsigned char family;
  74         union in_addr_union sender, destination;
  75         unsigned ttl;
  76 };
  77
  78 static inline uint8_t* DNS_PACKET_DATA(DnsPacket *p) {
  79         if (_unlikely_(!p))
  80                 return NULL;
  81
  82         if (p->data)
  83                 return p->data;
  84
  85         return ((uint8_t*) p) + ALIGN(sizeof(DnsPacket));
  86 }
  87
  88 #define DNS_PACKET_HEADER(p) ((DnsPacketHeader*) DNS_PACKET_DATA(p))
  89 #define DNS_PACKET_ID(p) DNS_PACKET_HEADER(p)->id
  90 #define DNS_PACKET_QR(p) ((be16toh(DNS_PACKET_HEADER(p)->flags) >> 15) & 1)
  91 #define DNS_PACKET_OPCODE(p) ((be16toh(DNS_PACKET_HEADER(p)->flags) >> 11) & 15)
  92 #define DNS_PACKET_RCODE(p) (be16toh(DNS_PACKET_HEADER(p)->flags) & 15)
  93 #define DNS_PACKET_TC(p) ((be16toh(DNS_PACKET_HEADER(p)->flags) >> 9) & 1)
  94 #define DNS_PACKET_QDCOUNT(p) be16toh(DNS_PACKET_HEADER(p)->qdcount)
  95 #define DNS_PACKET_ANCOUNT(p) be16toh(DNS_PACKET_HEADER(p)->ancount)
  96 #define DNS_PACKET_NSCOUNT(p) be16toh(DNS_PACKET_HEADER(p)->nscount)
  97 #define DNS_PACKET_ARCOUNT(p) be16toh(DNS_PACKET_HEADER(p)->arcount)
  98
  99 #define DNS_PACKET_MAKE_FLAGS(qr, opcode, aa, tc, rd, ra, ad, cd, rcode) \
 100         (((uint16_t) !!qr << 15) |  \
 101          ((uint16_t) (opcode & 15) << 11) | \
 102          ((uint16_t) !!aa << 10) | \
 103          ((uint16_t) !!tc << 9) | \
 104          ((uint16_t) !!rd << 8) | \
 105          ((uint16_t) !!ra << 7) | \
 106          ((uint16_t) !!ad << 5) | \
 107          ((uint16_t) !!cd << 4) | \
 108          ((uint16_t) (rcode & 15)))
 109
 110 static inline unsigned DNS_PACKET_RRCOUNT(DnsPacket *p) {
 111         return
 112                 (unsigned) DNS_PACKET_ANCOUNT(p) +
 113                 (unsigned) DNS_PACKET_NSCOUNT(p) +
 114                 (unsigned) DNS_PACKET_ARCOUNT(p);
 115 }
 116
 117 int dns_packet_new(DnsPacket **p, DnsProtocol protocol, size_t mtu);
 118 int dns_packet_new_query(DnsPacket **p, DnsProtocol protocol, size_t mtu);
 119
 120 DnsPacket *dns_packet_ref(DnsPacket *p);
 121 DnsPacket *dns_packet_unref(DnsPacket *p);
 122
 123 DEFINE_TRIVIAL_CLEANUP_FUNC(DnsPacket*, dns_packet_unref);
 124
 125 int dns_packet_validate(DnsPacket *p);
 126 int dns_packet_validate_reply(DnsPacket *p);
 127
 128 int dns_packet_append_uint8(DnsPacket *p, uint8_t v, size_t *start);
 129 int dns_packet_append_uint16(DnsPacket *p, uint16_t v, size_t *start);
 130 int dns_packet_append_string(DnsPacket *p, const char *s, size_t *start);
 131 int dns_packet_append_label(DnsPacket *p, const char *s, size_t l, size_t *start);
 132 int dns_packet_append_name(DnsPacket *p, const char *name, size_t *start);
 133 int dns_packet_append_key(DnsPacket *p, const DnsResourceKey *k, size_t *start);
 134
 135 int dns_packet_read(DnsPacket *p, size_t sz, const void **ret, size_t *start);
 136 int dns_packet_read_uint8(DnsPacket *p, uint8_t *ret, size_t *start);
 137 int dns_packet_read_uint16(DnsPacket *p, uint16_t *ret, size_t *start);
 138 int dns_packet_read_uint32(DnsPacket *p, uint32_t *ret, size_t *start);
 139 int dns_packet_read_string(DnsPacket *p, char **ret, size_t *start);
 140 int dns_packet_read_name(DnsPacket *p, char **ret, size_t *start);
 141 int dns_packet_read_key(DnsPacket *p, DnsResourceKey *ret, size_t *start);
 142 int dns_packet_read_rr(DnsPacket *p, DnsResourceRecord **ret, size_t *start);
 143
 144 void dns_packet_rewind(DnsPacket *p, size_t idx);
 145
 146 int dns_packet_skip_question(DnsPacket *p);
 147 int dns_packet_extract_rrs(DnsPacket *p);
 148
 149 enum {
 150         DNS_RCODE_SUCCESS = 0,
 151         DNS_RCODE_FORMERR = 1,
 152         DNS_RCODE_SERVFAIL = 2,
 153         DNS_RCODE_NXDOMAIN = 3,
 154         DNS_RCODE_NOTIMP = 4,
 155         DNS_RCODE_REFUSED = 5,
 156         DNS_RCODE_YXDOMAIN = 6,
 157         DNS_RCODE_YXRRSET = 7,
 158         DNS_RCODE_NXRRSET = 8,
 159         DNS_RCODE_NOTAUTH = 9,
 160         DNS_RCODE_NOTZONE = 10,
 161         DNS_RCODE_BADVERS = 16,
 162         DNS_RCODE_BADSIG = 16, /* duplicate value! */
 163         DNS_RCODE_BADKEY = 17,
 164         DNS_RCODE_BADTIME = 18,
 165         DNS_RCODE_BADMODE = 19,
 166         DNS_RCODE_BADNAME = 20,
 167         DNS_RCODE_BADALG = 21,
 168         DNS_RCODE_BADTRUNC = 22,
 169         _DNS_RCODE_MAX_DEFINED
 170 };
 171
 172 const char* dns_rcode_to_string(int i) _const_;
 173 int dns_rcode_from_string(const char *s) _pure_;
 174
 175 const char* dns_protocol_to_string(DnsProtocol p) _const_;
 176 DnsProtocol dns_protocol_from_string(const char *s) _pure_;
 177
 178 #define LLMNR_MULTICAST_IPV4_ADDRESS ((struct in_addr) { .s_addr = htobe32(224U << 24 | 252U) })
 179 #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 } })