Struct Header

pub struct Header { /* private fields */ }

Metadata for the Message struct.

RFC 1035, DOMAIN NAMES - IMPLEMENTATION AND SPECIFICATION, November 1987

4.1.1. Header section format

The header contains the following fields

                                   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|ZZ|AD|CD|   RCODE   |  /// AD and CD from RFC4035
    +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
    |                    QDCOUNT / ZCOUNT           |
    +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
    |                    ANCOUNT / PRCOUNT          |
    +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
    |                    NSCOUNT / UPCOUNT          |
    +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
    |                    ARCOUNT / ADCOUNT          |
    +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+

where

Z               Reserved for future use.  Must be zero in all queries
                and responses.

Implementations

impl Header

pub const fn new() -> Self

A default Header, not very useful.

pub fn response_from_request(header: &Self) -> Self

Construct a new header based off the request header. This copies over the RD (recursion-desired) and CD (checking-disabled), as well as the op_code and id of the request.

See https://datatracker.ietf.org/doc/html/rfc6895#section-2

The AA, TC, RD, RA, and CD bits are each theoretically meaningful
   only in queries or only in responses, depending on the bit.  The AD
   bit was only meaningful in responses but is expected to have a
   separate but related meaning in queries (see Section 5.7 of
   [RFC6840]).  Only the RD and CD bits are expected to be copied from
   the query to the response; however, some DNS implementations copy all
   the query header as the initial value of the response header.  Thus,
   any attempt to use a "query" bit with a different meaning in a
   response or to define a query meaning for a "response" bit may be
   dangerous, given the existing implementation.  Meanings for these
   bits may only be assigned by a Standards Action.

pub fn len() -> usize

Length of the header, always 12 bytes

pub fn set_id(&mut self, id: u16) -> &mut Self

Sets the id of the message, for queries this should be random.

pub fn set_message_type(&mut self, message_type: MessageType) -> &mut Self

Sets the message type, Queries and Updates both use Query.

pub fn set_op_code(&mut self, op_code: OpCode) -> &mut Self

Set the operation code for the message

pub fn set_authoritative(&mut self, authoritative: bool) -> &mut Self

From the server is specifies that it is an authoritative response.

pub fn set_truncated(&mut self, truncated: bool) -> &mut Self

Specifies that the records were too large for the payload.

See EDNS or TCP for resolutions to truncation.

pub fn set_recursion_desired(&mut self, recursion_desired: bool) -> &mut Self

Specify that the resolver should recursively request data from upstream DNS nodes

pub fn set_recursion_available( &mut self, recursion_available: bool, ) -> &mut Self

Specifies that recursion is available from this or the remote resolver

pub fn set_authentic_data(&mut self, authentic_data: bool) -> &mut Self

Specifies that the data is authentic, i.e. the resolver believes all data to be valid through DNSSEC

pub fn set_checking_disabled(&mut self, checking_disabled: bool) -> &mut Self

Used during recursive resolution to specified if a resolver should or should not validate DNSSEC signatures

pub fn flags(&self) -> Flags

A method to get all header flags (useful for Display purposes)

pub fn set_response_code(&mut self, response_code: ResponseCode) -> &mut Self

The low response code (original response codes before EDNS extensions)

pub fn set_query_count(&mut self, query_count: u16) -> &mut Self

Number or query records in the message

pub fn set_answer_count(&mut self, answer_count: u16) -> &mut Self

Number of answer records in the message

pub fn set_name_server_count(&mut self, name_server_count: u16) -> &mut Self

Number of name server records in the message

pub fn set_additional_count(&mut self, additional_count: u16) -> &mut Self

Number of additional records in the message

pub fn id(&self) -> u16

ID              A 16 bit identifier assigned by the program that
                generates any kind of query.  This identifier is copied
                the corresponding reply and can be used by the requester
                to match up replies to outstanding queries.

pub fn message_type(&self) -> MessageType

QR              A one bit field that specifies whether this message is a
                query (0), or a response (1).

pub fn op_code(&self) -> OpCode

OPCODE          A four bit field that specifies kind of query in this
                message.  This value is set by the originator of a query
                and copied into the response.  The values are: <see super::op_code>

pub fn authoritative(&self) -> bool

AA              Authoritative Answer - this bit is valid in responses,
                and specifies that the responding name server is an
                authority for the domain name in question section.

                Note that the contents of the answer section may have
                multiple owner names because of aliases.  The AA bit
                corresponds to the name which matches the query name, or
                the first owner name in the answer section.

pub fn truncated(&self) -> bool

TC              TrunCation - specifies that this message was truncated
                due to length greater than that permitted on the
                transmission channel.

pub fn recursion_desired(&self) -> bool

RD              Recursion Desired - this bit may be set in a query and
                is copied into the response.  If RD is set, it directs
                the name server to pursue the query recursively.
                Recursive query support is optional.

pub fn recursion_available(&self) -> bool

RA              Recursion Available - this be is set or cleared in a
                response, and denotes whether recursive query support is
                available in the name server.

pub fn authentic_data(&self) -> bool

RFC 4035, DNSSEC Resource Records, March 2005

3.1.6.  The AD and CD Bits in an Authoritative Response

  The CD and AD bits are designed for use in communication between
  security-aware resolvers and security-aware recursive name servers.
  These bits are for the most part not relevant to query processing by
  security-aware authoritative name servers.

  A security-aware name server does not perform signature validation
  for authoritative data during query processing, even when the CD bit
  is clear.  A security-aware name server SHOULD clear the CD bit when
  composing an authoritative response.

  A security-aware name server MUST NOT set the AD bit in a response
  unless the name server considers all RRsets in the Answer and
  Authority sections of the response to be authentic.  A security-aware
  name server's local policy MAY consider data from an authoritative
  zone to be authentic without further validation.  However, the name
  server MUST NOT do so unless the name server obtained the
  authoritative zone via secure means (such as a secure zone transfer
  mechanism) and MUST NOT do so unless this behavior has been
  configured explicitly.

  A security-aware name server that supports recursion MUST follow the
  rules for the CD and AD bits given in Section 3.2 when generating a
  response that involves data obtained via recursion.

pub fn checking_disabled(&self) -> bool

see is_authentic_data()

pub fn response_code(&self) -> ResponseCode

RCODE           Response code - this 4 bit field is set as part of
                responses.  The values have the following
                interpretation: <see super::response_code>

pub fn query_count(&self) -> u16

QDCOUNT         an unsigned 16 bit integer specifying the number of
                entries in the question section.

Return value

If this is a query, this will return the number of queries in the query section of the

pub fn answer_count(&self) -> u16

ANCOUNT         an unsigned 16 bit integer specifying the number of
                resource records in the answer section.

Return value

For query responses this is the number of records in the answer section, should be 0 for requests, for updates this is the count of prerequisite records.

pub fn name_server_count(&self) -> u16

for queries this is the nameservers which are authorities for the SOA of the Record for updates this is the update record count

NSCOUNT         an unsigned 16 bit integer specifying the number of name
                server resource records in the authority records
                section.

Return value

For query responses this is the number of authorities, or nameservers, in the name server section, for updates this is the number of update records being sent.

pub fn additional_count(&self) -> u16

ARCOUNT         an unsigned 16 bit integer specifying the number of
                resource records in the additional records section.

Return value

This is the additional record section count, this section may include EDNS options.

Trait Implementations

impl<'r> BinDecodable<'r> for Header

fn read(decoder: &mut BinDecoder<'r>) -> Result<Self, ProtoError>

Read the type from the stream

fn from_bytes(bytes: &'r [u8]) -> Result<Self, ProtoError>

Returns the object in binary form

impl BinEncodable for Header

fn emit(&self, encoder: &mut BinEncoder<'_>) -> Result<(), ProtoError>

Write the type to the stream

fn to_bytes(&self) -> Result<Vec<u8>, ProtoError>

Returns the object in binary form

impl Clone for Header

fn clone(&self) -> Header

Returns a copy of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for Header

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Default for Header

fn default() -> Self

Returns the “default value” for a type.

impl Display for Header

fn fmt(&self, f: &mut Formatter<'_>) -> Result<(), Error>

Formats the value using the given formatter.

impl Hash for Header

fn hash<__H: Hasher>(&self, state: &mut __H)

Feeds this value into the given Hasher.

fn hash_slice<H>(data: &[Self], state: &mut H)

where H: Hasher, Self: Sized,

Feeds a slice of this type into the given Hasher.

impl PartialEq for Header

fn eq(&self, other: &Header) -> bool

Tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &Rhs) -> bool

Tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.

impl PartialOrd for Header

fn partial_cmp(&self, other: &Header) -> Option<Ordering>

This method returns an ordering between self and other values if one exists.

fn lt(&self, other: &Rhs) -> bool

Tests less than (for self and other) and is used by the < operator.

fn le(&self, other: &Rhs) -> bool

Tests less than or equal to (for self and other) and is used by the <= operator.

fn gt(&self, other: &Rhs) -> bool

Tests greater than (for self and other) and is used by the > operator.

fn ge(&self, other: &Rhs) -> bool

Tests greater than or equal to (for self and other) and is used by the >= operator.

impl Copy for Header

impl Eq for Header

impl StructuralPartialEq for Header