https://gitlab.synchro.net/main/sbbs/-/commit/eee438b0b04b274843abd65b
Added Files:
exec/tests/system/findstr.js
Modified Files:
src/sbbs3/findstr.c
Log Message:
findstr: add IPv6 CIDR support for ip.can / .can matching (issue #1145)

The .can filter matching path (findstr.c) was IPv4-only Ä parse_cidr used sscanf("%u.%u.%u.%u/%u", ...) and is_cidr_match did a 32-bit XOR-shift, so
an IPv6 CIDR entry like `2001:db8::/32` in ip.can / ip-silent.can was
silently treated as a literal-string pattern and never matched a real connecting IPv6 client. This made the web server's rate-limit auto-filter asymmetric: rate_limit_key() correctly bucketizes IPv6 traffic by RateLimitSubnetPrefix6 and writes the subnet to ip.can, but the
accept-time read-back didn't enforce it.

Add parallel IPv6 functions: parse_ipv6_address (inet_pton), parse_ipv6_cidr, is_ipv6_cidr_match (byte-then-bit prefix compare). findstr_compare dispatches to the right family by which one the input parsed as; find2strs_in_list and find2strs pre-parse both forms up-front into a small internal findstr_ip_t.

Also fix two latent bugs surfaced by the new test cases:

- is_cidr_match's `>> (32 - subnet)` is undefined behavior when subnet
is 0 (a 32-bit shift by 32); on x86 it modulo-32s to 0, so /0
never matched anything except via exact host hit. Now guarded.

- parse_cidr returned uint32_t with 0 overloaded as both "parse failed"
and "0.0.0.0", so the literal pattern `0.0.0.0/0` (the canonical
"match-any IPv4") fell through to string-only matching. Changed to
bool + out-param, matching the new IPv6 convention.

Add exec/tests/system/findstr.js covering string-pattern features,
IPv4 CIDR (including /0 and boundaries), IPv6 exact + CIDR (/32 through
/128, with bit-boundary stress at /33), reverse-match (!) for both
families, cross-family no-false-match, and malformed-pattern rejection.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

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