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115 lines
2.7 KiB
115 lines
2.7 KiB
package weed_server
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import (
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"errors"
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"fmt"
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"mime/multipart"
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"net/textproto"
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"strconv"
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"strings"
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)
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// copied from src/pkg/net/http/fs.go
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// httpRange specifies the byte range to be sent to the client.
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type httpRange struct {
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start, length int64
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}
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func (r httpRange) contentRange(size int64) string {
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return fmt.Sprintf("bytes %d-%d/%d", r.start, r.start+r.length-1, size)
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}
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func (r httpRange) mimeHeader(contentType string, size int64) textproto.MIMEHeader {
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return textproto.MIMEHeader{
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"Content-Range": {r.contentRange(size)},
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"Content-Type": {contentType},
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}
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}
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// parseRange parses a Range header string as per RFC 2616.
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func parseRange(s string, size int64) ([]httpRange, error) {
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if s == "" {
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return nil, nil // header not present
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}
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const b = "bytes="
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if !strings.HasPrefix(s, b) {
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return nil, errors.New("invalid range")
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}
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var ranges []httpRange
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for _, ra := range strings.Split(s[len(b):], ",") {
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ra = strings.TrimSpace(ra)
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if ra == "" {
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continue
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}
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i := strings.Index(ra, "-")
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if i < 0 {
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return nil, errors.New("invalid range")
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}
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start, end := strings.TrimSpace(ra[:i]), strings.TrimSpace(ra[i+1:])
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var r httpRange
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if start == "" {
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// If no start is specified, end specifies the
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// range start relative to the end of the file.
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i, err := strconv.ParseInt(end, 10, 64)
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if err != nil {
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return nil, errors.New("invalid range")
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}
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if i > size {
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i = size
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}
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r.start = size - i
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r.length = size - r.start
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} else {
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i, err := strconv.ParseInt(start, 10, 64)
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if err != nil || i > size || i < 0 {
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return nil, errors.New("invalid range")
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}
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r.start = i
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if end == "" {
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// If no end is specified, range extends to end of the file.
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r.length = size - r.start
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} else {
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i, err := strconv.ParseInt(end, 10, 64)
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if err != nil || r.start > i {
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return nil, errors.New("invalid range")
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}
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if i >= size {
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i = size - 1
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}
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r.length = i - r.start + 1
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}
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}
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ranges = append(ranges, r)
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}
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return ranges, nil
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}
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// countingWriter counts how many bytes have been written to it.
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type countingWriter int64
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func (w *countingWriter) Write(p []byte) (n int, err error) {
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*w += countingWriter(len(p))
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return len(p), nil
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}
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// rangesMIMESize returns the number of bytes it takes to encode the
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// provided ranges as a multipart response.
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func rangesMIMESize(ranges []httpRange, contentType string, contentSize int64) (encSize int64) {
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var w countingWriter
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mw := multipart.NewWriter(&w)
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for _, ra := range ranges {
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mw.CreatePart(ra.mimeHeader(contentType, contentSize))
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encSize += ra.length
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}
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mw.Close()
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encSize += int64(w)
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return
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}
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func sumRangesSize(ranges []httpRange) (size int64) {
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for _, ra := range ranges {
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size += ra.length
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}
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return
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}
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