Enum EarlyDataSupport 

pub enum EarlyDataSupport {
    None,
    Supported,
}

Whether a transport can put a request into TLS 1.3 early data (0-RTT).

This is the floor, and it says less than it looks like

Self::Supported means only “this transport is able to offer early data”. It never means a particular request went into early data, and it never means one was accepted. In QUIC the acceptance verdict arrives after the response — measured at 8.63 ms against a response at 8.58 ms — so it is a future, not a property of a transport, and nothing about it can live in a value that Transport::capabilities determines once at construction.

Why the default is None with unusual force

Every other capability here follows the rule that a default must not be stronger than the truth, and the cost of breaking it is a buffered copy, a lost optimisation, or — for full_duplex — a deadlock. This one costs replay exposure: early data is data an attacker who captured it can send again, at a moment of their choosing, to a server that will act on it. So Capabilities::default() reports None, every transport that ships today reports None, and a transport that forgets this field reports None.

Reporting Supported is not sufficient to put anything in early data

It is necessary and nothing more. The gate is the caller’s, per request — see AllowEarlyData — and a transport that reports Supported must still refuse to place a request the caller did not mark.

Variants

None

This transport never offers early data. The conservative base, what Capabilities::default() returns, and the honest answer for every transport in this workspace except hclient-h3.

Supported

This transport can offer early data for a request the caller has marked with AllowEarlyData. See this enum’s doc for the three things it still does not mean.

Trait Implementations

impl Clone for EarlyDataSupport

fn clone(&self) -> EarlyDataSupport

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Copy for EarlyDataSupport

impl Debug for EarlyDataSupport

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

Formats the value using the given formatter.

impl Default for EarlyDataSupport

fn default() -> EarlyDataSupport

Returns the “default value” for a type.

impl Eq for EarlyDataSupport

impl PartialEq for EarlyDataSupport

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

Equality operator ==.

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

Inequality operator !=.

impl StructuralPartialEq for EarlyDataSupport