range_header.nx

range_header.nx -- parse HTTP Range request header. RFC 7233 §3.1. Range requests let a client ask for a byte range of a resource instead of the whole thing. Essential for: - Video / audio seeking (HTML5 <video> sends Range requests when you click the scrubber) - Resumable downloads (browsers retry interrupted downloads with \"Range: bytes=<last-byte-received>-\") - Large-file diff tools Format (most useful forms): Range: bytes=0-499 <- first 500 bytes Range: bytes=500- <- byte 500 to end Range: bytes=-500 <- last 500 bytes Range: bytes=0-499,1000-1499 <- multiple ranges (multipart) We only support bytes= unit; other units (chars=, seconds= in some video specs) are non-standard and rare. Invariants: RH1 Returns RangeSpec array with (start, end) resolved vs the file size. "-500" -> (size-500, size-1). "500-" -> (500, size-1). RH2 Ranges that extend past the file are clamped. RH3 Empty / unparseable input returns RH_ERR_FORMAT so caller falls back to serving 200 with full body.