Struct rustls::CommonState

pub struct CommonState { /* private fields */ }

Connection state common to both client and server connections.

Implementations

impl CommonState

pub fn wants_write(&self) -> bool

Returns true if the caller should call CommonState::write_tls as soon as possible.

pub fn is_handshaking(&self) -> bool

Returns true if the connection is currently performing the TLS handshake.

During this time plaintext written to the connection is buffered in memory. After Connection::process_new_packets has been called, this might start to return false while the final handshake packets still need to be extracted from the connection’s buffers.

pub fn peer_certificates(&self) -> Option<&[Certificate]>

Retrieves the certificate chain used by the peer to authenticate.

The order of the certificate chain is as it appears in the TLS protocol: the first certificate relates to the peer, the second certifies the first, the third certifies the second, and so on.

This is made available for both full and resumed handshakes.

For clients, this is the certificate chain of the server.

For servers, this is the certificate chain of the client, if client authentication was completed.

The return value is None until this value is available.

pub fn alpn_protocol(&self) -> Option<&[u8]>

Retrieves the protocol agreed with the peer via ALPN.

A return value of None after handshake completion means no protocol was agreed (because no protocols were offered or accepted by the peer).

pub fn negotiated_cipher_suite(&self) -> Option<SupportedCipherSuite>

Retrieves the ciphersuite agreed with the peer.

This returns None until the ciphersuite is agreed.

pub fn protocol_version(&self) -> Option<ProtocolVersion>

Retrieves the protocol version agreed with the peer.

This returns None until the version is agreed.

pub fn write_tls(&mut self, wr: &mut dyn Write) -> Result<usize, Error>

Writes TLS messages to wr.

On success, this function returns Ok(n) where n is a number of bytes written to wr (after encoding and encryption).

After this function returns, the connection buffer may not yet be fully flushed. The CommonState::wants_write function can be used to check if the output buffer is empty.

pub fn set_buffer_limit(&mut self, limit: Option<usize>)

Sets a limit on the internal buffers used to buffer unsent plaintext (prior to completing the TLS handshake) and unsent TLS records. This limit acts only on application data written through Connection::writer.

By default the limit is 64KB. The limit can be set at any time, even if the current buffer use is higher.

None means no limit applies, and will mean that written data is buffered without bound – it is up to the application to appropriately schedule its plaintext and TLS writes to bound memory usage.

For illustration: Some(1) means a limit of one byte applies: Connection::writer will accept only one byte, encrypt it and add a TLS header. Once this is sent via CommonState::write_tls, another byte may be sent.

Internal write-direction buffering

rustls has two buffers whose size are bounded by this setting:

Buffering of unsent plaintext data prior to handshake completion

Calls to Connection::writer before or during the handshake are buffered (up to the limit specified here). Once the handshake completes this data is encrypted and the resulting TLS records are added to the outgoing buffer.

Buffering of outgoing TLS records

This buffer is used to store TLS records that rustls needs to send to the peer. It is used in these two circumstances:

• by Connection::process_new_packets when a handshake or alert TLS record needs to be sent.
• by Connection::writer post-handshake: the plaintext is encrypted and the resulting TLS record is buffered.

This buffer is emptied by CommonState::write_tls.

pub fn send_close_notify(&mut self)

Queues a close_notify warning alert to be sent in the next CommonState::write_tls call. This informs the peer that the connection is being closed.

pub fn wants_read(&self) -> bool

Returns true if the caller should call Connection::read_tls as soon as possible.

If there is pending plaintext data to read with Connection::reader, this returns false. If your application respects this mechanism, only one full TLS message will be buffered by rustls.