| // Copyright (c) 2012 The Chromium OS Authors. All rights reserved. |
| // Use of this source code is governed by a BSD-style license that can be |
| // found in the LICENSE file. |
| |
| #ifndef PATCHPANEL_DNS_DNS_PROTOCOL_H_ |
| #define PATCHPANEL_DNS_DNS_PROTOCOL_H_ |
| |
| #include <stdint.h> |
| |
| #include "brillo/brillo_export.h" |
| |
| namespace patchpanel { |
| |
| // General constants and structs defined by the DNS and MDNS protocols. |
| // |
| // Direct interaction with DNS and MDNS, as well as parsing DNS and MDNS |
| // messages, should generally only be done within network stack code. |
| // Network-stack-external code should interact indirectly through network |
| // service APIs, e.g. NetworkContext::ResolveHost(). But these constants may |
| // still be useful for other minor purposes. |
| namespace dns_protocol { |
| |
| static const uint16_t kDefaultPort = 53; |
| // RFC 5353. |
| static const uint16_t kDefaultPortMulticast = 5353; |
| |
| // https://www.iana.org/assignments/multicast-addresses/multicast-addresses.xhtml#multicast-addresses-1 |
| static const char kMdnsMulticastGroupIPv4[] = "224.0.0.251"; |
| // https://www.iana.org/assignments/ipv6-multicast-addresses/ipv6-multicast-addresses.xhtml#link-local |
| static const char kMdnsMulticastGroupIPv6[] = "FF02::FB"; |
| |
| // DNS packet consists of a header followed by questions and/or answers. |
| // For the meaning of specific fields, please see RFC 1035 and 2535 |
| |
| // Header format. |
| // 1 1 1 1 1 1 |
| // 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 |
| // +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+ |
| // | ID | |
| // +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+ |
| // |QR| Opcode |AA|TC|RD|RA| Z|AD|CD| RCODE | |
| // +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+ |
| // | QDCOUNT | |
| // +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+ |
| // | ANCOUNT | |
| // +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+ |
| // | NSCOUNT | |
| // +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+ |
| // | ARCOUNT | |
| // +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+ |
| |
| // Question format. |
| // 1 1 1 1 1 1 |
| // 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 |
| // +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+ |
| // | | |
| // / QNAME / |
| // / / |
| // +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+ |
| // | QTYPE | |
| // +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+ |
| // | QCLASS | |
| // +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+ |
| |
| // Answer format. |
| // 1 1 1 1 1 1 |
| // 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 |
| // +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+ |
| // | | |
| // / / |
| // / NAME / |
| // | | |
| // +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+ |
| // | TYPE | |
| // +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+ |
| // | CLASS | |
| // +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+ |
| // | TTL | |
| // | | |
| // +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+ |
| // | RDLENGTH | |
| // +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--| |
| // / RDATA / |
| // / / |
| // +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+ |
| |
| #pragma pack(push) |
| #pragma pack(1) |
| |
| // On-the-wire header. All uint16_t are in network order. |
| struct BRILLO_EXPORT Header { |
| uint16_t id = 0; |
| uint16_t flags = 0; |
| uint16_t qdcount = 0; |
| uint16_t ancount = 0; |
| uint16_t nscount = 0; |
| uint16_t arcount = 0; |
| }; |
| |
| #pragma pack(pop) |
| |
| static const uint8_t kLabelMask = 0xc0; |
| static const uint8_t kLabelPointer = 0xc0; |
| static const uint8_t kLabelDirect = 0x0; |
| static const uint16_t kOffsetMask = 0x3fff; |
| |
| // In MDns the most significant bit of the rrclass is designated as the |
| // "cache-flush bit", as described in http://www.rfc-editor.org/rfc/rfc6762.txt |
| // section 10.2. |
| static const uint16_t kMDnsClassMask = 0x7FFF; |
| |
| // RFC 1035, section 3.1: To simplify implementations, the total length of |
| // a domain name (i.e., label octets and label length octets) is restricted |
| // to 255 octets or less. |
| static const int kMaxNameLength = 255; |
| |
| // RFC 1035, section 4.2.1: Messages carried by UDP are restricted to 512 |
| // bytes (not counting the IP nor UDP headers). |
| static const int kMaxUDPSize = 512; |
| |
| // RFC 6762, section 17: Messages over the local link are restricted by the |
| // medium's MTU, and must be under 9000 bytes |
| static const int kMaxMulticastSize = 9000; |
| |
| // RFC 1035, Section 4.1.3. |
| // TYPE (2 bytes) + CLASS (2 bytes) + TTL (4 bytes) + RDLENGTH (2 bytes) |
| static const int kResourceRecordSizeInBytesWithoutNameAndRData = 10; |
| |
| // DNS class types. |
| // |
| // https://www.iana.org/assignments/dns-parameters/dns-parameters.xhtml#dns-parameters-2 |
| static const uint16_t kClassIN = 1; |
| // RFC 6762, Section 10.2. |
| // |
| // For resource records sent through mDNS, the top bit of the class field in a |
| // resource record is repurposed to the cache-flush bit. This bit should only be |
| // used in mDNS transactions. |
| static const uint16_t kFlagCacheFlush = 0x8000; |
| |
| // DNS resource record types. |
| // |
| // https://www.iana.org/assignments/dns-parameters/dns-parameters.xhtml#dns-parameters-4 |
| static const uint16_t kTypeA = 1; |
| static const uint16_t kTypeCNAME = 5; |
| static const uint16_t kTypeSOA = 6; |
| static const uint16_t kTypePTR = 12; |
| static const uint16_t kTypeTXT = 16; |
| static const uint16_t kTypeAAAA = 28; |
| static const uint16_t kTypeSRV = 33; |
| static const uint16_t kTypeOPT = 41; |
| static const uint16_t kTypeNSEC = 47; |
| static const uint16_t kTypeHttps = 65; |
| static const uint16_t kTypeANY = 255; |
| |
| // Experimental DNS record types pending IANA assignment. |
| // |
| // The INTEGRITY RR type exists purely for measuring how the DNS ecosystem |
| // handles new RR types. |
| // https://docs.google.com/document/d/14eCqVyT_3MSj7ydqNFl1Yl0yg1fs6g24qmYUUdi5V-k/edit?usp=sharing |
| static const uint16_t kExperimentalTypeIntegrity = 65521; |
| |
| // DNS reply codes (RCODEs). |
| // |
| // https://www.iana.org/assignments/dns-parameters/dns-parameters.xhtml#dns-parameters-6 |
| static const uint8_t kRcodeNOERROR = 0; |
| static const uint8_t kRcodeFORMERR = 1; |
| static const uint8_t kRcodeSERVFAIL = 2; |
| static const uint8_t kRcodeNXDOMAIN = 3; |
| static const uint8_t kRcodeNOTIMP = 4; |
| static const uint8_t kRcodeREFUSED = 5; |
| |
| // DNS EDNS(0) option codes (OPT) |
| // |
| // https://www.iana.org/assignments/dns-parameters/dns-parameters.xhtml#dns-parameters-11 |
| static const uint16_t kEdnsPadding = 12; |
| |
| // DNS header flags. |
| // |
| // https://www.iana.org/assignments/dns-parameters/dns-parameters.xhtml#dns-parameters-12 |
| static const uint16_t kFlagResponse = 0x8000; |
| static const uint16_t kFlagAA = 0x400; // Authoritative Answer - response flag. |
| static const uint16_t kFlagRD = 0x100; // Recursion Desired - query flag. |
| static const uint16_t kFlagTC = 0x200; // Truncated - server flag. |
| |
| } // namespace dns_protocol |
| |
| } // namespace patchpanel |
| |
| #endif // PATCHPANEL_DNS_DNS_PROTOCOL_H_ |
