Add TLS 1.3 Cover Traffic Support (RFC 8446 Appendix E)

[stenslae]

Description

Implemented TLS 1.3 cover traffic, allowing the application to send empty, padded records to obscure actual traffic patterns.

Issue #11086

Testing

Added test coverage

Checklist

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

[wolfSSL-Fenrir-bot]

Fenrir Automated Review — PR #11357

Scan targets checked: wolfcrypt-rs-bugs, wolfssl-bugs, wolfssl-src

Findings: 1
1 finding(s) posted as inline comments (see file-level comments below)

This review was generated automatically by Fenrir. Reported findings require changes before merge.

[wolfSSL-Fenrir-bot]

Tls13ClearCoverTraffic() called from wolfSSL_clear() under the wrong preprocessor guard · API contract violations

Tls13ClearCoverTraffic() is defined in src/tls13.c, whose body is #if !defined(NO_TLS) && defined(WOLFSSL_TLS13), but the new call site is guarded only by #ifdef WOLFSSL_TLS13. configure.ac:1354 keeps WOLFSSL_TLS13 defined for --disable-tls, so a --disable-tls (non-cryptonly) build compiles ssl.c with an undefined reference. Other TLS-only work in the same function (e.g. TLSX_FreeAll at ssl.c:5736) is guarded with !defined(NO_TLS).

Fix: Change the guard to #if defined(WOLFSSL_TLS13) && !defined(NO_TLS).

[github-actions]

MemBrowse Memory Report

gcc-arm-cortex-m3

• FLASH: .text +24 B (+0.0%, 125,691 B / 262,144 B, total: 48% used)

gcc-arm-cortex-m4-dtls13

• FLASH: .text +384 B (+0.2%, 186,812 B / 1,048,576 B, total: 18% used)

gcc-arm-cortex-m4-openssl-compat

• FLASH: .text +320 B (+0.0%, 780,972 B / 1,048,576 B, total: 74% used)

gcc-arm-cortex-m4-pq

• FLASH: .text +448 B (+0.1%, 301,828 B / 1,048,576 B, total: 29% used)

gcc-arm-cortex-m4-rsa-only

• FLASH: .text +320 B (+0.1%, 332,000 B / 1,048,576 B, total: 32% used)

gcc-arm-cortex-m4-tls13

• FLASH: .text +448 B (+0.2%, 242,447 B / 262,144 B, total: 92% used)

gcc-arm-cortex-m7-pq

• FLASH: .text +384 B (+0.1%, 302,724 B / 1,048,576 B, total: 29% used)

gcc-arm-cortex-m7-tls13

• FLASH: .text +384 B (+0.2%, 242,447 B / 262,144 B, total: 92% used)

linuxkm-standard

• Data: __patchable_function_entries +24 B (+0.0%, 49,768 B)
  No memory changes detected for:
• gcc-arm-cortex-m0plus
• gcc-arm-cortex-m4
• gcc-arm-cortex-m4-baremetal
• gcc-arm-cortex-m4-crypto-only
• gcc-arm-cortex-m4-min-ecc
• gcc-arm-cortex-m4-pkcs7
• gcc-arm-cortex-m4-sp-math
• gcc-arm-cortex-m4-tls12
• gcc-arm-cortex-m7
• linuxkm-pie
• stm32-sim-stm32h753