102 lines
2.3 KiB
Go
102 lines
2.3 KiB
Go
// Copyright (C) 2019 Storj Labs, Inc.
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// See LICENSE for copying information.
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package ranger
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import (
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"bytes"
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"context"
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"fmt"
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"io"
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"io/ioutil"
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"log"
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"net/http"
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"strconv"
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)
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type httpRanger struct {
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URL string
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size int64
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}
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// HTTPRanger turns an HTTP URL into a Ranger
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func HTTPRanger(ctx context.Context, url string) (_ Ranger, err error) {
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defer mon.Task()(&ctx)(&err)
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resp, err := http.Head(url)
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if err != nil {
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return nil, err
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}
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defer func() {
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if err := resp.Body.Close(); err != nil {
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log.Printf("Failed to close body: %v", err)
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}
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}()
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if resp.StatusCode != http.StatusOK {
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return nil, Error.New("unexpected status code: %d (expected %d)",
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resp.StatusCode, http.StatusOK)
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}
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contentLength := resp.Header.Get("Content-Length")
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size, err := strconv.Atoi(contentLength)
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if err != nil {
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return nil, err
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}
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return &httpRanger{
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URL: url,
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size: int64(size),
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}, nil
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}
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// HTTPRangerSize creates an HTTPRanger with known size.
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// Use it if you know the content size. This will safe the extra HEAD request
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// for retrieving the content size.
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func HTTPRangerSize(url string, size int64) Ranger {
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return &httpRanger{
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URL: url,
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size: size,
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}
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}
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// Size implements Ranger.Size
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func (r *httpRanger) Size() int64 {
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return r.size
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}
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// Range implements Ranger.Range
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func (r *httpRanger) Range(ctx context.Context, offset, length int64) (_ io.ReadCloser, err error) {
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defer mon.Task()(&ctx)(&err)
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if offset < 0 {
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return nil, Error.New("negative offset")
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}
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if length < 0 {
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return nil, Error.New("negative length")
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}
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if offset+length > r.size {
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return nil, Error.New("range beyond end")
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}
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if length == 0 {
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return ioutil.NopCloser(bytes.NewReader([]byte{})), nil
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}
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client := &http.Client{}
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req, err := http.NewRequest("GET", r.URL, nil)
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if err != nil {
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return nil, err
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}
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req.Header.Add("Range", fmt.Sprintf("bytes=%d-%d", offset, offset+length-1))
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resp, err := client.Do(req)
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if err != nil {
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return nil, err
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}
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if resp.StatusCode != http.StatusPartialContent {
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if err := resp.Body.Close(); err != nil {
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return nil, Error.New("Error: (%v) Failed to close Body :: unexpected status code: %d (expected %d)",
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err, resp.StatusCode, http.StatusPartialContent)
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}
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return nil, Error.New("unexpected status code: %d (expected %d)",
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resp.StatusCode, http.StatusPartialContent)
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}
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return resp.Body, nil
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}
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