Struct domain::bits::compose::ComposeSnapshot

pub struct ComposeSnapshot { /* fields omitted */ }

A snapshot of a composer’s state.

This type is actually a composer all by itself, that is, it implements AsMut<Composer>. However, if necessary, it can be rolled back to the state the composer had when it was created forgetting about all changes made since.

This process currently is not transitive. While a new snapshot can be created from both a composer and a snapshot, when you roll back you get a composer. Ie., you can only roll back once. This is enough for the purpose, reuse of messages when transitioning through several servers in a resolver.

Methods

impl ComposeSnapshot

pub fn new(composer: Composer) -> Self

Creates a new snapshot from the given composer.

pub fn rewind(&mut self)

Rewinds the state to when the snapshot was taken.

pub fn rollback(self) -> Composer

Rolls back to a composer with state as when the snapshot was taken.

pub fn commit(self) -> Composer

Trades in the snapshot to a composer with all changes commited.

Methods from Deref<Target = Composer>

pub fn preview(&mut self) -> &[u8]

Returns a reference to the underlying vector as it looks now.

This method updates the length shim in stream mode, hence the need for a &mut self.

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

Returns the message bytes as far as they are assembled yet.

The returned bytes slice really only contains the message bytes and neither whatever was contained in the vector with which the composer was posssibly created nor the length prefix of stream mode.

pub fn so_far_mut(&mut self) -> &mut [u8]

Returns the message bytes as far as they are assembled yet.

The returned bytes slice really only contains the message bytes and neither whatever was contained in the vector with which the composer was posssibly created nor the length prefix of stream mode.

pub fn pos(&self) -> usize

Returns the current position.

The returned value is identical to the current overall length of the underlying bytes vec.

pub fn start(&self) -> usize

Returns the position where the message starts.

This is identical to having called self.pos() right after self was created.

pub fn delta(&self, pos: usize) -> usize

Returns the length of data added since the given position.

Panics

Panics if pos is larger than the current position.

pub fn mark_checkpoint(&mut self)

Marks the current position as a point for truncation.

If the length of the resulting message exceeds its predefined maximum size for the first time after a call to this method, the data will be cut back to the length it had when the method was called. If this happens, any further writing will fail.

pub fn is_truncated(&self) -> bool

Returns whether the target has been truncated.

pub fn compose_bytes(&mut self, data: &[u8]) -> ComposeResult<()>

Pushes a bytes slice to the end of the message.

pub fn compose_empty(&mut self, len: usize) -> ComposeResult<()>

Pushes placeholder bytes to the end of the message.

In particular, if successful, the message will have been extended by len octets of value zero,

pub fn compose_u8(&mut self, data: u8) -> ComposeResult<()>

Pushes a single octet to the end of the message.

pub fn compose_u16(&mut self, data: u16) -> ComposeResult<()>

Pushes an unsigned 16-bit word to the end of the message.

Since DNS data is big-endian, data will be converted to that endianess if necessary.

pub fn compose_u32(&mut self, data: u32) -> ComposeResult<()>

Pushes a unsigned 32-bit word to the end of the message.

Since DNS data is big-endian, data will be converted to that endianess if necessary.

pub fn compose_dname<N: DName>(&mut self, name: &N) -> ComposeResult<()>

Pushes a domain name to the end of the message.

pub fn compose_dname_compressed<N: DName>(     &mut self,     name: &N ) -> ComposeResult<()>

Pushes a domain name to the end of the message using name compression.

Since compression is only allowed in a few well-known places per RFC 1123 and RFC 3597, this isn’t the default behaviour.

pub fn update_bytes(&mut self, pos: usize, data: &[u8])

Updates the bytes starting at the given position.

Panics

Panics if the bytes slice is longer than the data assembled since the given position.

pub fn update_u8(&mut self, pos: usize, data: u8)

Updates the octet at the given position.

Panics

Panics if there has not been at least one byte of data assembled since the given position.

pub fn update_u16(&mut self, pos: usize, data: u16)

Updates an unsigned 16-bit word starting at the given position.

Panics

Panics if there has not been at least two bytes of data assembled since the given position.

pub fn update_u32(&mut self, pos: usize, data: u32)

Updates an unsigned 32-bit word starting at the given position.

Panics

Panics if there has not been at least four bytes of data assembled since the given position.

Trait Implementations

impl Clone for ComposeSnapshot

fn clone(&self) -> ComposeSnapshot

Returns a copy of the value.

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

Performs copy-assignment from source.

impl Debug for ComposeSnapshot

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

Formats the value using the given formatter.

impl Deref for ComposeSnapshot

type Target = Composer

The resulting type after dereferencing.

fn deref(&self) -> &Self::Target

Dereferences the value.

impl DerefMut for ComposeSnapshot

fn deref_mut(&mut self) -> &mut Self::Target

Mutably dereferences the value.

impl AsRef<Composer> for ComposeSnapshot

fn as_ref(&self) -> &Composer

Performs the conversion.

impl AsMut<Composer> for ComposeSnapshot

fn as_mut(&mut self) -> &mut Composer

Performs the conversion.