feat(app): add internal components batch 6
This commit is contained in:
吴璨
@@ -0,0 +1,230 @@
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package app
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import (
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"errors"
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"fmt"
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"io"
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"net/http"
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"strconv"
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"strings"
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"time"
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)
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type mediaByteRange struct {
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start int64
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end int64
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total int64
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}
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func parseMediaByteRange(value string) (mediaByteRange, bool) {
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var result mediaByteRange
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unit, value, ok := strings.Cut(strings.TrimSpace(value), " ")
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if !ok || !strings.EqualFold(unit, "bytes") {
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return result, false
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}
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span, total, ok := strings.Cut(value, "/")
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if !ok {
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return result, false
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}
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start, end, ok := strings.Cut(span, "-")
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if !ok {
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return result, false
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}
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for index, field := range []string{start, end, total} {
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if field == "" || strings.IndexFunc(field, func(char rune) bool { return char < '0' || char > '9' }) >= 0 {
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return result, false
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}
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number, err := strconv.ParseInt(field, 10, 64)
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if err != nil {
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return result, false
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}
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switch index {
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case 0:
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result.start = number
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case 1:
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result.end = number
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case 2:
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result.total = number
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}
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}
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return result, result.start <= result.end && result.end < result.total
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}
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func mediaRequestAttempts(retries int) int {
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return min(3, max(1, retries))
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}
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func identityMediaResponse(response *http.Response) bool {
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encoding := strings.TrimSpace(response.Header.Get("Content-Encoding"))
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return !response.Uncompressed && (encoding == "" || strings.EqualFold(encoding, "identity")) &&
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!strings.HasPrefix(strings.ToLower(response.Header.Get("Content-Type")), "multipart/")
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}
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type resumableMediaReader struct {
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proxy *hlsProxy
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request *http.Request
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body io.ReadCloser
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span mediaByteRange
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length int64
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read int64
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etag string
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modified string
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validator string
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resumable bool
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attempts int
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maxAttempts int
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pending error
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failure error
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recovered bool
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}
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func (proxy *hlsProxy) mediaReader(request *http.Request, response *http.Response) *resumableMediaReader {
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reader := &resumableMediaReader{
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proxy: proxy, request: request.Clone(request.Context()), body: response.Body,
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length: -1, maxAttempts: mediaRequestAttempts(proxy.retries) - 1,
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etag: strings.TrimSpace(response.Header.Get("ETag")),
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modified: strings.TrimSpace(response.Header.Get("Last-Modified")),
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}
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if response.Request != nil && response.Request.URL != nil {
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reader.request.URL = response.Request.URL
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}
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if response.ContentLength > 0 {
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reader.length = response.ContentLength
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}
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if response.StatusCode == http.StatusOK && reader.length > 0 && response.Header.Get("Content-Range") == "" {
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reader.span = mediaByteRange{end: reader.length - 1, total: reader.length}
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reader.resumable = true
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} else if response.StatusCode == http.StatusPartialContent {
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if span, valid := parseMediaByteRange(response.Header.Get("Content-Range")); valid {
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length := span.end - span.start + 1
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if response.ContentLength < 0 || response.ContentLength == length {
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reader.span, reader.length, reader.resumable = span, length, true
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}
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}
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}
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reader.resumable = reader.resumable && request.Method == http.MethodGet && identityMediaResponse(response)
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if len(reader.etag) >= 2 && strings.HasPrefix(reader.etag, `"`) && strings.HasSuffix(reader.etag, `"`) {
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reader.validator = reader.etag
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} else if _, err := http.ParseTime(reader.modified); err == nil {
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reader.validator = reader.modified
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}
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return reader
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}
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func (reader *resumableMediaReader) Close() error {
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return reader.body.Close()
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}
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func (reader *resumableMediaReader) Read(buffer []byte) (int, error) {
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if len(buffer) == 0 {
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return 0, nil
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}
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for {
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if err := reader.request.Context().Err(); err != nil {
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return 0, err
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}
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if reader.failure != nil {
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return 0, reader.failure
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}
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if reader.length >= 0 && reader.read == reader.length {
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if reader.attempts > 0 && !reader.recovered && reader.proxy.diagnostic != nil {
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reader.recovered = true
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reader.proxy.diagnostic(diagnosticEvent{Level: "info", Event: "media.recovered", Host: reader.request.URL.Hostname(),
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OffsetBytes: reader.span.start + reader.read, TotalBytes: reader.span.total, Attempt: reader.attempts, Message: "媒体续读完成"})
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}
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return 0, io.EOF
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}
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if reader.pending != nil {
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err := reader.pending
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if errors.Is(err, io.EOF) {
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if reader.length < 0 {
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return 0, io.EOF
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}
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err = io.ErrUnexpectedEOF
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}
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if reader.resumable && reader.attempts < reader.maxAttempts {
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if err = reader.resume(); err == nil {
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reader.pending = nil
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continue
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}
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}
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if canceled := reader.request.Context().Err(); canceled != nil {
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return 0, canceled
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}
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reader.failure = fmt.Errorf("媒体资源读取不完整（已读取 %d 字节，续读 %d 次）: %w", reader.read, reader.attempts, err)
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return 0, reader.failure
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}
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if reader.length >= 0 && int64(len(buffer)) > reader.length-reader.read {
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buffer = buffer[:reader.length-reader.read]
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}
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count, err := reader.body.Read(buffer)
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reader.read += int64(count)
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reader.pending = err
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if count > 0 || err == nil {
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return count, nil
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}
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}
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}
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func (reader *resumableMediaReader) resume() error {
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_ = reader.body.Close()
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reader.body = http.NoBody
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var lastErr error
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for reader.attempts < reader.maxAttempts {
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ctx := reader.request.Context()
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if reader.attempts > 0 {
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timer := time.NewTimer(time.Duration(reader.attempts) * 250 * time.Millisecond)
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select {
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case <-timer.C:
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case <-ctx.Done():
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timer.Stop()
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return ctx.Err()
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}
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}
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if err := ctx.Err(); err != nil {
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return err
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}
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request := reader.request.Clone(ctx)
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request.Header.Set("Range", fmt.Sprintf("bytes=%d-%d", reader.span.start+reader.read, reader.span.end))
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request.Header.Del("If-Range")
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if reader.validator != "" {
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request.Header.Set("If-Range", reader.validator)
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}
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reader.attempts++
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if reader.proxy.diagnostic != nil {
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reader.proxy.diagnostic(diagnosticEvent{Level: "warn", Event: "media.resume", Host: reader.request.URL.Hostname(),
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OffsetBytes: reader.span.start + reader.read, TotalBytes: reader.span.total, Attempt: reader.attempts, Message: "媒体连接中断，正在续读"})
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}
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response, err := reader.proxy.client.Do(request)
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if err != nil {
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lastErr = err
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continue
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}
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if err = reader.validateContinuation(response); err == nil {
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reader.body = response.Body
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return nil
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}
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_ = response.Body.Close()
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lastErr = err
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if response.StatusCode != http.StatusRequestTimeout && response.StatusCode != http.StatusTooManyRequests && response.StatusCode < 500 {
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return err
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}
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}
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return lastErr
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}
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func (reader *resumableMediaReader) validateContinuation(response *http.Response) error {
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if response.StatusCode != http.StatusPartialContent {
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return fmt.Errorf("媒体续读未返回所需字节范围（HTTP %d）", response.StatusCode)
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}
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span, valid := parseMediaByteRange(response.Header.Get("Content-Range"))
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if !valid || span.start != reader.span.start+reader.read || span.end != reader.span.end || span.total != reader.span.total ||
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response.ContentLength >= 0 && response.ContentLength != reader.length-reader.read {
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return errors.New("媒体续读字节范围或长度不一致")
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}
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if !identityMediaResponse(response) || reader.etag != "" && strings.TrimSpace(response.Header.Get("ETag")) != reader.etag ||
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reader.modified != "" && strings.TrimSpace(response.Header.Get("Last-Modified")) != reader.modified {
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return errors.New("媒体续读资源已变化")
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}
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return nil
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}
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