Struct MtuNegotiator 

pub struct MtuNegotiator { /* private fields */ }

Manages MTU discovery via binary search probing.

The caller is responsible for actually sending probe packets — this struct tracks state and interprets results.

Implementations

impl MtuNegotiator

pub fn new(config: MtuConfig) -> Self

Create a new negotiator with the given config.

pub fn start_discovery(&mut self) -> usize

Start MTU discovery. Returns the size of the first probe packet to send.

The caller should send a packet of exactly this size and then call record_probe() with the result.

pub fn record_probe(&mut self, size: usize, success: bool) -> Option<usize>

Record the result of a probe.

size — the probe packet size that was sent. success — true if the probe was acknowledged, false if it was dropped/timed out.

Returns the next probe size to send, or None if discovery is complete.

pub fn check_probe_timeout(&self) -> Option<usize>

Check if a pending probe has timed out.

If it has, call record_probe(size, false) to register the failure. Returns the timed-out probe size if applicable.

pub fn current_mtu(&self) -> usize

Returns the current best known MTU.

pub fn state(&self) -> &MtuState

Returns the current negotiation state.

pub fn is_complete(&self) -> bool

Returns true if MTU discovery is complete.

pub fn recommended_fragment_size(&self) -> usize

Returns the recommended fragment_size for VCLConfig based on the current MTU, subtracting all protocol headers.

pub fn set_mtu(&mut self, mtu: usize)

Force-set the MTU without probing (e.g. from OS PMTUD or known config).

pub fn fallback_to_min(&mut self)

Fall back to the minimum safe MTU.

pub fn path_mtu(&self) -> PathMtu

Returns a PathMtu snapshot of the current state.

pub fn total_probes(&self) -> u64

Returns total probes sent.

pub fn successful_probes(&self) -> u64

Returns total successful probes.

pub fn probe_history(&self) -> &[(usize, bool)]

Returns the full probe history as (size, success) pairs.