ddn.net.dtls.client12

DTLS 1.2 client handshake state machine (RFC 6347).

Drives the DTLS 1.2 client handshake as a resumable state machine. Adapts the TLS 1.2 handshake for datagram transports with:

  • DTLS record framing (13-byte header)
  • DTLS handshake framing (12-byte header with message_seq)
  • Flight-based retransmission with exponential backoff
  • Cookie exchange (HelloVerifyRequest)
  • Handshake message fragmentation
  • Anti-replay protection

Reuses cryptographic primitives from the TLS 1.2 implementation: PRF (Tls12Prf), AEAD (TlsAead), key exchange (X25519, ECDH P-256), certificate parsing, and signature verification.

var DTLS_1_2_RECORD_VERSION
class Dtls12Client

Types 1

classDtls12Client

DTLS 1.2 client handshake engine.

Drives the client side of a DTLS 1.2 handshake over a datagram transport. Uses flight-based retransmission with exponential backoff and supports the HelloVerifyRequest cookie exchange for DoS mitigation.

Call handshake() repeatedly until it returns TlsProgress.DONE. Between calls, wait for socket readiness as indicated by the return value.

Fields
DtlsTransport transport_
DtlsTimerSink timer_
DatagramEndpoint serverAddr_
Dtls12ClientPhase phase_
ushort messageSeq_
ushort epoch_
ulong recordSeq_
SecureRandom rng_
DtlsFlight pendingFlight_
int retryCount_
ubyte[32] clientRandom_
ubyte[32] serverRandom_
ubyte[] preMasterSecret_
ubyte[] masterSecret_
ubyte[] receivedCookie_
X25519PrivateKey ecdhePrivate_
NamedGroup selectedGroup_
string serverName_
DtlsVersion minVersion_
DtlsVersion maxVersion_
string[] alpnProtocols_
SrtpProfile[] srtpProfiles_
string negotiatedAlpn_
CipherSuiteId negotiatedCipher_
DtlsVersion negotiatedVersion_
SrtpProfile negotiatedSrtpProfile_
Tls12Prf prf_
TranscriptHash transcript_
TlsAead writeAead_
TlsAead readAead_
X509Certificate[] peerX509Certs_
TlsCertificateChain peerCerts_
TlsVerifyMode verifyMode_
DtlsVerifyCallback verifyCallback_
NativeTlsTrustStore trustStore_
DtlsFragmentBuffer reassembly_
ubyte[] pendingDatagram_
Methods
void setMinVersion(DtlsVersion ver) @safe pure nothrow @nogcSets the minimum DTLS version.
void setMaxVersion(DtlsVersion ver) @safe pure nothrow @nogcSets the maximum DTLS version.
void setAlpnProtocols(string[] protocols) @safe pure nothrowSets the ALPN protocols.
void setSrtpProfiles(SrtpProfile[] profiles) @safe pure nothrow
void setVerifyMode(TlsVerifyMode mode) @safe pure nothrow @nogcSets the certificate verification mode.
void setVerifyCallback(DtlsVerifyCallback callback) @safe pure nothrowSets a custom certificate verification callback.
void setTrustStore(NativeTlsTrustStore trustStore) @safe pure nothrowSets the trust store for certificate chain validation.
TlsProgress handshake() @trustedPerforms or continues the DTLS 1.2 client handshake.
ubyte[] buildDtlsClientHello(const(ubyte)[] cookie)Builds a DTLS ClientHello handshake message.
bool processServerResponse(const(ubyte)[] datagram)Process a received datagram during the handshake.
bool processHandshakePayload(const(ubyte)[] payload)Process a handshake payload from a DTLS record.
bool dispatchHandshakeType(HandshakeType msgType, const(ubyte)[] body)Dispatch a complete handshake message to the appropriate handler.
void processServerHello(const(ubyte)[] body)Process a ServerHello message body.
void processServerHelloExtensions(const(ubyte)[] extData)Process extensions from a ServerHello.
void processCertificate(const(ubyte)[] body)Process a Certificate message body.
private void verifyPeerCertificates()Verify the peer's certificate chain against the trust store.
void processServerKeyExchange(const(ubyte)[] body)Process a ServerKeyExchange message body.
void performKeyExchange(NamedGroup group, const(ubyte)[] peerPubKey)Perform ECDHE key exchange.
void verifyServerKeyExchange(SignatureScheme sigScheme, const(ubyte)[] params, const(ubyte)[] signature)Verify the server's signature on ServerKeyExchange parameters.
ubyte[] buildClientKeyExchange()Builds a ClientKeyExchange handshake message.
ubyte[] buildChangeCipherSpec()Builds a ChangeCipherSpec record.
void deriveKeys()Derives master secret and key material from the premaster secret.
ubyte[] buildFinished()Builds a Finished handshake message.
bool processHelloVerify(const(ubyte)[] datagram)Process a datagram that may contain a HelloVerifyRequest.
const(ubyte)[] extractHelloVerifyCookie(const(ubyte)[] body)Extract the cookie from a HelloVerifyRequest body.
void updateTranscript(HandshakeType msgType, const(ubyte)[] body)Update the handshake transcript hash with a DTLS handshake message.
ubyte[] wrapHandshakeMessage(HandshakeType msgType, const(ubyte)[] body)Wraps a handshake message body in a DTLS handshake header.
ubyte[] wrapInRecord(ContentType contentType, const(ubyte)[] payload)Wraps a handshake message in a DTLS record.
ubyte[] buildDtlsRecord(ContentType contentType, const(ubyte)[] payload)Builds a complete DTLS record with 13-byte header.
ubyte[] encryptRecord(ContentType contentType, const(ubyte)[] plaintext)Encrypts a record payload using the current write AEAD.
const(ubyte)[] receiveDatagram()Receive a single datagram from the transport.
void feedDatagram(const(ubyte)[] data) @trustedFeed a received datagram for processing.
void sendDatagram(const(ubyte)[] data)Send a datagram via the transport.
void sendFlight(ubyte[][] records)Send a flight of records as one or more datagrams.
void scheduleRetransmit()Schedule retransmission timer for the current flight.
void retransmitFlight()Retransmit the pending flight.
Dtls12ClientPhase phase() @property const @safe pure nothrow @nogcReturns: The current handshake phase.
CipherSuiteId negotiatedCipher() @property const @safe pure nothrow @nogcReturns: The negotiated cipher suite.
DtlsVersion negotiatedVersion() @property const @safe pure nothrow @nogcReturns: The negotiated DTLS version.
string alpnProtocol() @property const @safe pure nothrowReturns: The negotiated ALPN protocol.
TlsCertificateChain peerCertificates() @property @trustedReturns: The peer's certificate chain.
ushort epoch() @property const @safe pure nothrow @nogcReturns: The current epoch.
SrtpProfile negotiatedSrtpProfile() @property const @safe pure nothrow @nogc
ubyte[] srtpMasterSecret() @property @safe pure nothrow @nogc
ubyte[] srtpClientRandom() @property @safe pure nothrow @nogc
ubyte[] srtpServerRandom() @property @safe pure nothrow @nogc
TlsAead writeAead() @propertyReturns: The write AEAD cipher (after key derivation).
TlsAead readAead() @propertyReturns: The read AEAD cipher (after key derivation).
Constructors
this(DtlsTransport transport, DtlsTimerSink timer, DatagramEndpoint serverAddr, string serverName)Constructs a DTLS 1.2 client handshake engine.

Variables 1

enumvarDTLS_1_2_RECORD_VERSION = [0xFE, 0xFD]

DTLS 1.2 record version used on the wire.