Struct ServerConfig

pub struct ServerConfig {
    pub ignore_client_order: bool,
    pub max_fragment_size: Option<usize>,
    pub session_storage: Arc<dyn StoresServerSessions + Sync + Send>,
    pub ticketer: Arc<dyn ProducesTickets>,
    pub cert_resolver: Arc<dyn ResolvesServerCert>,
    pub alpn_protocols: Vec<Vec<u8>>,
    pub key_log: Arc<dyn KeyLog>,
    pub enable_secret_extraction: bool,
    pub max_early_data_size: u32,
    pub send_half_rtt_data: bool,
    pub send_tls13_tickets: usize,
    /* private fields */
}

Common configuration for a set of server sessions.

Making one of these is cheap, though one of the inputs may be expensive: gathering trust roots from the operating system to add to the RootCertStore passed to a ClientCertVerifier builder may take on the order of a few hundred milliseconds.

These must be created via the ServerConfig::builder() or ServerConfig::builder_with_provider() function.

Defaults

• ServerConfig::max_fragment_size: the default is None (meaning 16kB).
• ServerConfig::session_storage: the default stores 256 sessions in memory.
• ServerConfig::alpn_protocols: the default is empty – no ALPN protocol is negotiated.
• ServerConfig::key_log: key material is not logged.
• ServerConfig::send_tls13_tickets: 4 tickets are sent.

Fields

ignore_client_order: bool

Ignore the client’s ciphersuite order. Instead, choose the top ciphersuite in the server list which is supported by the client.

max_fragment_size: Option<usize>

The maximum size of plaintext input to be emitted in a single TLS record. A value of None is equivalent to the TLS maximum of 16 kB.

rustls enforces an arbitrary minimum of 32 bytes for this field. Out of range values are reported as errors from ServerConnection::new.

Setting this value to a little less than the TCP MSS may improve latency for stream-y workloads.

session_storage: Arc<dyn StoresServerSessions + Sync + Send>

How to store client sessions.

ticketer: Arc<dyn ProducesTickets>

How to produce tickets.

cert_resolver: Arc<dyn ResolvesServerCert>

How to choose a server cert and key. This is usually set by [ConfigBuilder::with_single_cert] or [ConfigBuilder::with_cert_resolver]. For async applications, see also [Acceptor].

alpn_protocols: Vec<Vec<u8>>

Protocol names we support, most preferred first. If empty we don’t do ALPN at all.

key_log: Arc<dyn KeyLog>

How to output key material for debugging. The default does nothing.

enable_secret_extraction: bool

Allows traffic secrets to be extracted after the handshake, e.g. for kTLS setup.

max_early_data_size: u32

Amount of early data to accept for sessions created by this config. Specify 0 to disable early data. The default is 0.

Read the early data via [ServerConnection::early_data].

The units for this are both plaintext bytes, and ciphertext bytes, depending on whether the server accepts a client’s early_data or not. It is therefore recommended to include some slop in this value to account for the unknown amount of ciphertext expansion in the latter case.

send_half_rtt_data: bool

Whether the server should send “0.5RTT” data. This means the server sends data after its first flight of handshake messages, without waiting for the client to complete the handshake.

This can improve TTFB latency for either server-speaks-first protocols, or client-speaks-first protocols when paired with “0RTT” data. This comes at the cost of a subtle weakening of the normal handshake integrity guarantees that TLS provides. Note that the initial ClientHello is indirectly authenticated because it is included in the transcript used to derive the keys used to encrypt the data.

This only applies to TLS1.3 connections. TLS1.2 connections cannot do this optimisation and this setting is ignored for them. It is also ignored for TLS1.3 connections that even attempt client authentication.

This defaults to false. This means the first application data sent by the server comes after receiving and validating the client’s handshake up to the Finished message. This is the safest option.

send_tls13_tickets: usize

How many TLS1.3 tickets to send immediately after a successful handshake.

Because TLS1.3 tickets are single-use, this allows a client to perform multiple resumptions.

The default is 4.

If this is 0, no tickets are sent and clients will not be able to do any resumption.

Implementations

impl ServerConfig

pub fn builder() -> ConfigBuilder<ServerConfig, WantsVerifier>

Create a builder for a server configuration with the default [CryptoProvider]: [crypto::ring::default_provider] and safe ciphersuite and protocol defaults.

For more information, see the [ConfigBuilder] documentation.

pub fn builder_with_protocol_versions( versions: &[&'static SupportedProtocolVersion], ) -> ConfigBuilder<ServerConfig, WantsVerifier>

Create a builder for a server configuration with the default [CryptoProvider]: [crypto::ring::default_provider], safe ciphersuite defaults and the provided protocol versions.

Panics if provided an empty slice of supported versions.

For more information, see the [ConfigBuilder] documentation.

pub fn builder_with_provider( provider: Arc<CryptoProvider>, ) -> ConfigBuilder<ServerConfig, WantsVersions>

Create a builder for a server configuration with a specific [CryptoProvider].

This will use the provider’s configured ciphersuites. You must additionally choose which protocol versions to enable, using with_protocol_versions or with_safe_default_protocol_versions and handling the Result in case a protocol version is not supported by the provider’s ciphersuites.

For more information, see the [ConfigBuilder] documentation.

Trait Implementations

impl Clone for ServerConfig

fn clone(&self) -> ServerConfig

Returns a copy of the value.

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

Performs copy-assignment from source.

impl Debug for ServerConfig

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

Formats the value using the given formatter.

impl ConfigSide for ServerConfig