Add missing input validation to VERIFY_ACERT and VERIFY cert handler

[jackctj117]

This pull request adds important input validation checks to the certificate verification request handlers in src/wh_server_cert.c. These changes improve the robustness and security of the server by ensuring that incoming requests are well-formed and do not cause buffer overflows or invalid memory accesses.

Input validation improvements:

• Added a check to ensure the request size is at least as large as the expected request structure before processing verify ACERT requests, returning an error if not (WH_ERROR_ABORTED).
• Added checks to both verify and verify ACERT request handlers to ensure the certificate data length does not exceed the remaining request size, returning an error (WH_ERROR_BADARGS) if the data would overflow. [1] [2]

[Copilot]

Pull request overview

Adds request-boundary validation to certificate verification handlers to prevent out-of-bounds reads and malformed request processing.

Changes:

• Added bounds checks to ensure cert_len does not exceed remaining request payload for VERIFY and VERIFY_ACERT.
• Added minimum request-size validation for VERIFY_ACERT before translating/parsing the request.

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[Copilot]

In the VERIFY handler, the request is translated before any minimum-size check, which can allow an out-of-bounds read if req_size < sizeof(req). Additionally, req_size - sizeof(req) can underflow (if unsigned) and incorrectly bypass the bounds check. Add a minimum request-size validation (like the VERIFY_ACERT path) before wh_MessageCert_TranslateVerifyRequest(...), and only compute req_size - sizeof(req) after confirming req_size >= sizeof(req).

[Copilot]

The newly added early-exit error handling repeats a multi-line pattern (set rc → translate response → set *out_resp_size → break) that now appears in multiple handlers. Consider extracting a small helper (or local utility macro) for formatting and emitting error responses to reduce duplication and make future validation additions less error-prone. This is optional, but would improve readability as validations expand.