DTLS 1.2
DTLS 1.2 uses the TLS 1.2 handshake and cipher suite implementation over the DTLS datagram record layer. Header: noxtls_tls12.h with shared DTLS declarations in noxtls_dtls_common.h.
Use noxtls_dtls12_context_init to initialize a tls12_context_t for datagram transport. Configure MTU, retransmission, cookies, replay handling, and anti-amplification settings with the shared DTLS API.
Features
| Area | Support |
|---|---|
| Record layer | DTLS 1.2 13-byte record header with epoch and 48-bit sequence number |
| Handshake | TLS 1.2 handshake over datagrams |
| Fragmentation | Handshake fragmentation and reassembly |
| Loss recovery | Flight buffering and retransmission timer configuration |
| Replay protection | Sliding replay window |
| DoS mitigation | HelloVerifyRequest cookie generation and verification |
| Transport | Callback-based datagram I/O using the TLS common callback API |
RFC 6347 conformance (0.3.0). The handshake transcript uses 12-byte DTLS handshake headers, Finished is a DTLS handshake message, the MAC and AEAD sequence number include the epoch, read and write epochs are separate, every record in a datagram is processed, records from another epoch and replays are discarded silently, and retransmissions use new record sequence numbers. DTLS 1.2 interoperates with OpenSSL; earlier NoxTLS builds used a NoxTLS-only wire format and cannot complete a handshake with 0.3.0. Not supported: several handshake messages in one record, cookies longer than 32 bytes, and max_fragment_length applied to DTLS fragmentation.
API
noxtls_dtls12_context_init
noxtls_return_t noxtls_dtls12_context_init(tls12_context_t *ctx, tls_role_t role);
Initialize a TLS 1.2 context for DTLS 1.2 operation.
Returns: noxtls_return_t.
Handshake and Data
After initialization, use the TLS 1.2 handshake and data functions on the same context:
Typical Setup
tls12_context_t ctx;
noxtls_dtls12_context_init(&ctx, TLS_ROLE_CLIENT);
noxtls_tls_set_io_callbacks(&ctx.base.base, send_cb, recv_cb, user_data);
noxtls_dtls_set_mtu(&ctx.base, 1200);
dtls_set_retransmit(&ctx.base, 1000, 2000, 5);
noxtls_tls12_connect(&ctx);
See DTLS common API for record, fragmentation, cookie, and replay helper functions.