Struct async_dnssd::TxtRecord

pub struct TxtRecord(_);

Key-Value container that uses DNS TXT RDATA as representation

The binary representation can be used as RDATA for DNS-SD TXT Records (see RFC 6763, section 6).

Each entry results in one string in the TXT represenation; TXT RDATA contains many (but at least one) possibly empty strings, each up to 255 bytes.

Key and value are separated by the first = in an entry, and the key must consist of printable ASCII characters (0x20…0x7E) apart from =. Keys should be 9 characters or fewer.

Values can be any binary string (but the total length of an entry cannot exceed 255 bytes).

An entry also can have no value at all (which is different from having an empty value) if there is no = separator in the entry.

Implementations

impl TxtRecord

pub fn new() -> Self

Constructs a new, empty TxtRecord.

pub fn parse_vec(data: Vec<u8>) -> Option<Self>

Parse binary blob as TXT RDATA

Same as parse but takes ownership of buffer.

pub fn parse(data: &[u8]) -> Option<Self>

Parse some binary blob as TXT RDATA

A single empty string (encoded as 0x00) gets decoded as “empty” TxtRecord (i.e. the reverse th rdata()); an empty slice is treated the same, although it wouldn’t be valid RDATA.

This only fails when the length of a chunk exceeds the remaining data.

pub fn with_capacity(capacity: usize) -> Self

Constructs a new, empty TxtRecord with the specified capacity.

The inserting operations will still reallocate if necessary.

pub fn reserve(&mut self, additional: usize)

Reserves capacity for at least additional more bytes to be used by inserting operations.

Each entry requires 1 byte for the total length, the length of the key for the key; if there is a value 1 byte for the separator = and the length of the value for the value.

pub fn is_empty(&self) -> bool

Returns true if the TxtRecord contains no elements (both in bytes and key-value entries).

pub fn clear(&mut self)

Clears the TxtRecord, removing all entries.

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

if not empty this returns valid TXT RDATA, otherwise just an empty slice.

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

always returns valid TXT RDATA; when the container is empty it will return a TXT record with a single empty string (i.e. &[0x00]).

pub fn iter(&self) -> TxtRecordIter<'_>

Iterate over all (key, value) pairs.

pub fn get(&self, key: &[u8]) -> Option<Option<&[u8]>>

Get value for entry with given key

Returns None if there is no such entry, Some(None) if the entry exists but has no value, and Some(Some(value)) if the entry exists and has a value.

pub fn remove(&mut self, key: &[u8])

Remove entry with given key (if it exists)

pub fn set(
    &mut self,
    key: &[u8],
    value: Option<&[u8]>
) -> Result<(), TxtRecordError>

Insert or update the entry with key to have the given value or on value

pub fn set_no_value(&mut self, key: &[u8]) -> Result<(), TxtRecordError>

Insert or update the entry with key to have no value

pub fn set_value(
    &mut self,
    key: &[u8],
    value: &[u8]
) -> Result<(), TxtRecordError>

Insert or update the entry with key to have the given value

Trait Implementations

impl Clone for TxtRecord

fn clone(&self) -> TxtRecord

Returns a copy of the value.

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

Performs copy-assignment from source.

impl Default for TxtRecord

fn default() -> Self

Returns the “default value” for a type.

impl<'a> IntoIterator for &'a TxtRecord

type IntoIter = TxtRecordIter<'a>

Which kind of iterator are we turning this into?

type Item = (&'a [u8], Option<&'a [u8]>)

The type of the elements being iterated over.

fn into_iter(self) -> Self::IntoIter

Creates an iterator from a value.