More various fixes (fixes-6)

[gasbytes]

• fix for report from fuzzers (+ regression test for it);
• m-241 from f. (+ regression test for it)

[Copilot]

Pull request overview

Fixes checksum handling for odd-length ICMP payloads and hardens TCP input validation to prevent malformed IP length handling, with regression tests covering both cases.

Changes:

• Add odd-length tail-byte handling to ICMP checksum calculation.
• Add ip.len minimum-header-length validation in tcp_input() to avoid invalid subtraction/processing.
• Add unit/regression tests for odd-length ICMP echo reply checksum and TCP ip.len < IP_HEADER_LEN.

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 3 comments.

File	Description
src/wolfip.c	Fixes ICMP checksum computation for odd lengths and adds TCP IP length validation guard.
src/test/unit/unit.c	Adds regression tests for the above ICMP and TCP fixes.

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