Struct domain::bits::header::Header

pub struct Header { /* fields omitted */ }

The first part of the header of a DNS message.

This type represents the information contained in the first four bytes of the header: the message ID, opcode, rcode, and the various flags.

The header is layed out like this:

                                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   |
+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+

Methods are available for each of accessing each of these fields. See Field Access below.

Most of this is defined in RFC 1035, except for the AD and CD flags, which are defined in RFC 4035.

Methods

impl Header

Creation and Conversion

pub fn new() -> Header

Creates a new header.

The new header has all fields as either zero or false. Thus, the opcode will be Opcode::Query and the response code will be Rcode::NoError.

pub fn from_message(s: &[u8]) -> &Header

Creates a header reference from a bytes slice of a message.

Panics

This function panics if the bytes slice is too short.

pub fn from_message_mut(s: &mut [u8]) -> &mut Header

Creates a mutable header reference from a bytes slice of a message.

Panics

This function panics if the bytes slice is too short.

pub fn as_bytes(&self) -> &[u8]

Returns a reference to the underlying bytes slice.

impl Header

Field Access

pub fn id(&self) -> u16

Returns the value of the ID field.

The ID field is an identifier chosen by whoever created a query and is copied into a response. It serves to match incoming responses to their request.

pub fn set_id(&mut self, value: u16)

Sets the value of the ID field.

pub fn set_random_id(&mut self)

Sets the value of the ID field to a randomly chosen number.

pub fn qr(&self) -> bool

Returns whether the QR bit is set.

The QR bit specifies whether this message is a query (false) or a response (true). In other words, this bit is actually stating whether the message is not a query.

pub fn set_qr(&mut self, set: bool)

Sets the value of the QR bit.

pub fn opcode(&self) -> Opcode

Returns the value of the Opcode field.

This field specifies the kind of query this message contains. See the Opcode type for more information on the possible values and their meaning. Normal queries have the variant Opcode::Query which is also the value set when creating a new header.

pub fn set_opcode(&mut self, opcode: Opcode)

Sets the value of the opcode field.

pub fn aa(&self) -> bool

Returns whether the AA bit is set.

Using this bit, a name server generating a response states whether it is authoritative for the requested domain name, ie., whether this response is an authoritative answer. The field has no meaning in a query.

pub fn set_aa(&mut self, set: bool)

Sets the value of the AA bit.

pub fn tc(&self) -> bool

Returns whether the TC bit is set.

The truncation bit is set if there was more data available then fit into the message. This is typically used when employing datagram transports such as UDP to signal to try again using a stream transport such as TCP.

pub fn set_tc(&mut self, set: bool)

Sets the value of the TC bit.

pub fn rd(&self) -> bool

Returns whether the RD bit is set.

The recursion desired bit may be set in a query to ask the name server to try and recursively gather a response if it doesn’t have the data available locally. The bit’s value is copied into the response.

pub fn set_rd(&mut self, set: bool)

Sets the value of the RD bit.

pub fn ra(&self) -> bool

Returns whether the RA bit is set.

In a response, the recursion available bit denotes whether the responding name server supports recursion. It has no meaning in a query.

pub fn set_ra(&mut self, set: bool)

Sets the value of the RA bit.

pub fn z(&self) -> bool

Returns whether the reserved bit is set.

This bit must be false in all queries and responses.

pub fn set_z(&mut self, set: bool)

Sets the value of the reserved bit.

pub fn ad(&self) -> bool

Returns whether the AD bit is set.

The authentic data bit is used by security-aware recursive name servers to indicate that it considers all RRsets in its response to be authentic.

pub fn set_ad(&mut self, set: bool)

Sets the value of the AD bit.

pub fn cd(&self) -> bool

Returns whether the CD bit is set.

The checking disabled bit is used by a security-aware resolver to indicate that it does not want upstream name servers to perform verification but rather would like to verify everything itself.

pub fn set_cd(&mut self, set: bool)

Sets the value of the CD bit.

pub fn rcode(&self) -> Rcode

Returns the value of the RCODE field.

The response code is used in a response to indicate what happened when processing the query. See the Rcode type for information on possible values and their meaning.

pub fn set_rcode(&mut self, rcode: Rcode)

Sets the value of the RCODE field.

Trait Implementations

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() -> Header

Returns the "default value" for a type.

impl PartialEq for Header

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

This method tests for self and other values to be equal, and is used by ==.

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

This method tests for !=.