135 lines
3.5 KiB
Go
135 lines
3.5 KiB
Go
/*
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* Copyright 2020 The Dragonfly Authors
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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package clientutil
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import (
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"errors"
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"fmt"
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"net/textproto"
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"strconv"
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"strings"
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)
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// Range specifies the byte range to be sent to the client.
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type Range struct {
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Start, Length int64
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}
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// ErrNoOverlap is returned by ParseRange if first-byte-pos of
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// all of the byte-range-spec values is greater than the content size.
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var ErrNoOverlap = errors.New("invalid range: failed to overlap")
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// ParseRange parses a Range header string as per RFC 7233.
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// ErrNoOverlap is returned if none of the ranges overlap.
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// Example:
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// "Range": "bytes=100-200"
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// "Range": "bytes=-50"
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// "Range": "bytes=150-"
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// "Range": "bytes=0-0,-1"
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//
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// copy from go/1.15.2 net/http/fs.go ParseRange
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func ParseRange(s string, size int64) ([]Range, 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 []Range
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noOverlap := false
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for _, ra := range strings.Split(s[len(b):], ",") {
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ra = textproto.TrimString(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 := textproto.TrimString(ra[:i]), textproto.TrimString(ra[i+1:])
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var r Range
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if start == "" {
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// If no Serve is specified, end specifies the
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// range Serve 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 < 0 {
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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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// If the range begins after the size of the content,
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// then it does not overlap.
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noOverlap = true
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continue
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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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if noOverlap && len(ranges) == 0 {
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// The specified ranges did not overlap with the content.
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return nil, ErrNoOverlap
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}
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return ranges, nil
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}
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// Example:
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// "Content-Range": "bytes 100-200/1000"
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// "Content-Range": "bytes 100-200/*"
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func GetContentRange(start, end, total int64) string {
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// unknown total: -1
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if total == -1 {
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return fmt.Sprintf("bytes %d-%d/*", start, end)
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}
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return fmt.Sprintf("bytes %d-%d/%d", start, end, total)
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}
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func MustParseRange(s string, size int64) Range {
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rs, err := ParseRange(s, size)
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if err != nil {
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panic(fmt.Sprintf("parse range %q error: %s", s, err))
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}
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if len(rs) != 1 {
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panic(fmt.Sprintf("parse range length must be 1"))
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}
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return rs[0]
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}
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