[sebastian-carpenter]

Description

The DTLS13 code does not currently support Encrypted Client Hello (ECH). Error instead of attempting to make a connection.

Connections would fail regardless for both the server and client. This just prevents it from being attempted.

The client will error when TLSX_PopulateExtensions() runs.

The server will error at wolfSSL_accept() or wolfSSL_accept_TLSv13().

Addresses GH #12013

Testing

./configure --enable-ech --enable-dtls13
./tests/unit.test -test_wolfSSL_Dtls_ECH_unsupported

Checklist

• added tests
• updated/added doxygen
• updated appropriate READMEs
• Updated manual and documentation

[github-actions]

MemBrowse Memory Report · Explore what changed →

zephyr-frdm_rw612

• FLASH: log_const_area -8 B, rodata -8 B, text +1,592 B (+0.6%, 284,040 B / 67,108,864 B, total: 0% used)

No memory changes detected for:

• gcc-arm-cortex-m0plus
• gcc-arm-cortex-m3
• gcc-arm-cortex-m4
• gcc-arm-cortex-m4-baremetal
• gcc-arm-cortex-m4-crypto-only
• gcc-arm-cortex-m4-dtls13
• gcc-arm-cortex-m4-min-ecc
• gcc-arm-cortex-m4-openssl-compat
• gcc-arm-cortex-m4-pkcs7
• gcc-arm-cortex-m4-pq
• gcc-arm-cortex-m4-rsa-only
• gcc-arm-cortex-m4-sp-math
• gcc-arm-cortex-m4-tls12
• gcc-arm-cortex-m4-tls13
• gcc-arm-cortex-m7
• gcc-arm-cortex-m7-pq
• gcc-arm-cortex-m7-tls13
• stm32-sim-stm32h753

---

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[Copilot]

🟢 Approval recommended

The supplied review status reports no active issues, supporting approval of the change.

No open issues 🎉

What changed in this PR

This pull request prevents unsupported Encrypted Client Hello (ECH) use over DTLS and adds regression tests for DTLS 1.2 and 1.3 behavior.

Changes:

• Rejects client-side ECH configuration during DTLS extension population.
• Rejects server-side ECH configuration during generic and TLS 1.3 accept paths.
• Adds memory-I/O tests for ECH rejection and ECH-disabled handshakes.

File	Summary
tests/​api.c	Adds DTLS ECH rejection and ECH-disabled handshake coverage.
src/​tls13.c	Rejects ECH-configured DTLS connections in the TLS 1.3 server path.
src/​tls.c	Contains a moderate issue: the client-side guard should use WOLFSSL_DTLS rather than WOLFSSL_DTLS13 so DTLS 1.2 builds also reject configured ECH before sending data.
src/​ssl_api_hs.c	Rejects ECH-configured DTLS connections in the generic server accept path.

This pull request requires changes.

_{Review effort: Lite}