IIS: IPv6 link-local client addresses break IP matching ("IPmatch: bad IPv6 specification")

Description

On Windows, when a client connects to the ModSecurity IIS module from an IPv6 link-local address (fe80::/10), rule processing fails with:

ModSecurity: IPmatch: bad IPv6 specification "fe80::186d:7ec:8f88:4a0a%6".
ModSecurity: Rule processing failed (id=905110, msg=).

Any rule that matches against REMOTE_ADDR / client IP (e.g. id=905110) is affected for such clients.

Root cause

In iis/mymodule.cpp, GetIpAddr() converts the client sockaddr to a string with GetNameInfo(..., NI_NUMERICHOST). On Windows, GetNameInfo appends the IPv6 zone/scope identifier ("%") to link-local addresses, because sin6_scope_id is the interface index for fe80::/10 addresses (Microsoft docs: "fe80::208:74ff:feda:625c%5").

ModSecurity's IP-match parser only accepts plain RFC 4291 addresses and rejects the "%6" zone suffix, so the rule aborts.

Impact

False rule-processing failures (and effectively bypassed IP-based rules) for any client arriving over a link-local IPv6 address on Windows/IIS.

Fix

Strip the "%" suffix from the textual IP passed to ModSecurity in GetIpAddr(). The binary address (sin6_addr) used for the socket is unchanged, and the zone id is irrelevant for IP matching.

See PR: https://github.com/owasp-modsecurity/ModSecurity/pull/3631