Altair-sh
71 lines
1.6 KiB
Go
71 lines
1.6 KiB
Go
package http
|
|
|
|
import (
|
|
"strconv"
|
|
"strings"
|
|
)
|
|
|
|
type RangeResult int
|
|
|
|
const (
|
|
// no header, invalid syntax or multiple ranges: serve the full body with 200
|
|
RangeNone RangeResult = iota
|
|
// serve bytes [start, end] (inclusive) with 206
|
|
RangeOK
|
|
// respond with 416
|
|
RangeUnsatisfiable
|
|
)
|
|
|
|
// ParseRange parses a "Range" header value for a resource of the given size.
|
|
// Only a single byte range is supported: "bytes=a-b", "bytes=a-", "bytes=-n".
|
|
// Anything else is ignored (RangeNone), which RFC 9110 §14.2 allows.
|
|
func ParseRange(header string, size int64) (start, end int64, r RangeResult) {
|
|
header = strings.TrimSpace(header)
|
|
if header == "" {
|
|
return 0, 0, RangeNone
|
|
}
|
|
spec, ok := strings.CutPrefix(header, "bytes=")
|
|
if !ok || strings.ContainsRune(spec, ',') {
|
|
return 0, 0, RangeNone
|
|
}
|
|
firstStr, lastStr, ok := strings.Cut(spec, "-")
|
|
if !ok {
|
|
return 0, 0, RangeNone
|
|
}
|
|
firstStr = strings.TrimSpace(firstStr)
|
|
lastStr = strings.TrimSpace(lastStr)
|
|
|
|
if firstStr == "" {
|
|
// suffix range: last n bytes
|
|
n, ok := parseNonNegative(lastStr)
|
|
if !ok {
|
|
return 0, 0, RangeNone
|
|
}
|
|
if n == 0 || size == 0 {
|
|
return 0, 0, RangeUnsatisfiable
|
|
}
|
|
return max(size-n, 0), size - 1, RangeOK
|
|
}
|
|
|
|
first, ok := parseNonNegative(firstStr)
|
|
if !ok {
|
|
return 0, 0, RangeNone
|
|
}
|
|
last := size - 1
|
|
if lastStr != "" {
|
|
last, ok = parseNonNegative(lastStr)
|
|
if !ok || last < first {
|
|
return 0, 0, RangeNone
|
|
}
|
|
}
|
|
if first >= size {
|
|
return 0, 0, RangeUnsatisfiable
|
|
}
|
|
return first, min(last, size-1), RangeOK
|
|
}
|
|
|
|
func parseNonNegative(s string) (int64, bool) {
|
|
n, err := strconv.ParseUint(s, 10, 63)
|
|
return int64(n), err == nil
|
|
}
|