ssl_sess: sanity test session cache save and restore.

[philljj]

Description

• Add unit tests for mem[save, restore]_session_cache(), and file [save, restore]_session_cache.
• Correct save/restore functions to save the entire cache, instead of just the first SessionRow member.
• Add more sanitization of imported sessions.
• Comment and indent #endifs better.

Fixes zd#22196.

Fixes F-7286, F-7287, F-7288, F-7292.

Testing

• added unit test test_wolfSSL_session_cache_restore
• multitest all-c89-clang-tidy

./autogen.sh || exit 1
./configure --enable-savesession --enable-opensslextra \
  --enable-context-extra-user-data --enable-session-ticket --enable-debug \ 
  --enable-sessioncerts \ 
  CFLAGS="-DHAVE_EX_DATA_CLEANUP_HOOKS -DENABLE_SESSION_CACHE_ROW_LOCK" \
  || exit 1                
make && make test || exit 1

[Copilot]

Pull request overview

This PR fixes persistent session-cache save/restore to serialize the full cache (not just a partial SessionRow), adds additional sanitization on restore, and adds API tests to validate both memory- and file-based cache persistence paths.

Changes:

• Introduces wolfssl/ssl_sess.h to centralize session-cache layout constants/types and persistence sizing macros.
• Updates src/ssl_sess.c persistence code to save full SessionRow data and restore without clobbering active row locks; expands restore-time sanitization.
• Adds a new unit test test_wolfSSL_session_cache_restore covering memsave/memrestore and save/restore session-cache APIs.

Reviewed changes

Copilot reviewed 7 out of 7 changed files in this pull request and generated 5 comments.

Show a summary per file

File	Description
wolfssl/ssl_sess.h	New internal header consolidating session-cache sizing/layout and persistence helpers.
wolfssl/internal.h	Improves #endif comments around session/ticket-related conditionals.
wolfssl/include.am	Adds the new internal header to noinst_HEADERS.
tests/api/test_session.h	Registers the new session-cache restore unit test.
tests/api/test_session.c	Adds the new session-cache restore unit test implementation.
src/ssl_sess.c	Fixes persistence to copy full rows, avoid clobbering locks, and sanitize restored sessions.
CMakeLists.txt	Ensures ssl_sess.h remains excluded from installed public headers.

Suppressed comments (3)

tests/api/test_session.c:1970

• test_read_file() logs the wrong variable on read failure (it prints ret instead of the read count) and uses "%d" with a size_t, which is undefined behavior on LP64 platforms.

    read = XFREAD(cache_mem, sizeof(struct sess_cache_t), 1, file);
    if (read != 1) {
        WOLFSSL_MSG_EX("error: read %s: %d", fname, ret);
        goto read_file_cleanup;
    }

tests/api/test_session.c:2102

• In the remove() failure path, the fprintf prints ret instead of the remove() return code rc, which makes the diagnostic misleading.

        int rc = remove(fname);
        if (rc) {
            fprintf(stderr, "remove(%s) failed: %d\n", fname, ret);
        }

wolfssl/internal.h:4977

• This #endif closes a "#ifndef NO_SESSION_CACHE" block, but the comment currently says "NO_SESSION_CACHE" (missing the negation), which is confusing when scanning the struct layout.

#ifndef NO_SESSION_CACHE
    int                cacheRow;          /* row in session cache     */
#endif /* NO_SESSION_CACHE */

---

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MemBrowse Memory Report

gcc-arm-cortex-m4-openssl-compat

• FLASH: .text +64 B (+0.0%, 772,908 B / 1,048,576 B, total: 74% 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-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
• linuxkm-pie
• linuxkm-standard
• stm32-sim-stm32h753