nx_ipaddr.nx

ipaddr.nx -- IPv4 + IPv6 address parse / format. Used by: net.nx (connect / bind with human-readable addresses), X.509 subjectAltName IP entries, HTTP Host header validation, access-control lists. IPv4: dotted quad "a.b.c.d" where each octet is 0..255. Packed as network-order u32 (big-endian): a in high byte. IPv6: colon-separated "1234:abcd:..." with optional "::" run- length compression. 16-byte value (8 x u16 hextets). Parser handles both full + compressed forms; emitter always produces compressed canonical form (RFC 5952). Invariants: IP1 All decoders are bounds-checked; malformed input returns a negative error code, never garbage. IP2 Encoders never overflow the output buffer -- caller guarantees >= 16 chars for IPv4 ("255.255.255.255\0"), >= 40 chars for IPv6 (":ffff:ffff:...:ffff\0"). IP3 Round-trip exact for canonical forms. Compressed IPv6 that uses "::" is normalised on re-format; the byte-level value round-trips even if the string doesn't. IP4 No IPv4-mapped IPv6 (::ffff:a.b.c.d) handling today. That form is RFC 4291 but complicates parsing; callers needing it can decompose manually.