Struct DotStufferState 

pub struct DotStufferState { /* private fields */ }

Streaming version of the RFC 5321 dot-stuffer.

Unlike dot_stuff_and_terminate, this processes the message body one chunk at a time, keeping memory usage at O(chunk size) rather than O(body size). Suitable for large messages and memory-constrained runtimes.

Usage

use wasm_smtp::protocol::DotStufferState;

let mut stuffer = DotStufferState::new();

// Process each chunk.
let chunk1 = b"Subject: test\r\n\r\n";
let out1 = stuffer.process_chunk(chunk1);

let chunk2 = b".dotted line\r\nend\r\n";
let out2 = stuffer.process_chunk(chunk2);

// Produce the end-of-data terminator.
let terminator = stuffer.finish();

// on-wire: out1 + out2 + terminator
assert_eq!(&out2[..2], b".."); // dot-stuffed
assert_eq!(terminator, b".\r\n");

Implementations

impl DotStufferState

pub const fn new() -> Self

Create a new state machine, ready to process the first chunk.

pub fn process_chunk(&mut self, chunk: &[u8]) -> Vec<u8>

Dot-stuff one chunk and return the processed bytes.

The returned Vec is slightly larger than chunk only when one or more lines in the chunk begin with .. All other bytes pass through unchanged.

process_chunk with an empty slice is a no-op and returns an empty Vec.

Cross-chunk dot-stuffing

The state machine correctly handles dots that appear at the start of a line which spans two consecutive chunks. For example, if chunk N ends with \r\n and chunk N+1 starts with ., the leading dot in chunk N+1 will be stuffed.

pub fn finish(self) -> Vec<u8>

Consume the state machine and produce the end-of-DATA bytes.

The output is:

• \r\n.\r\n if the body did not end with \r\n (or was empty).
• .\r\n if the body already ended with \r\n.

This matches the semantics of dot_stuff_and_terminate exactly.

Trait Implementations

impl Clone for DotStufferState

fn clone(&self) -> DotStufferState

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for DotStufferState

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

Formats the value using the given formatter.

impl Default for DotStufferState

fn default() -> Self

Returns the “default value” for a type.