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http.go
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http.go
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// Copyright (C) 2019 Storj Labs, Inc.
// See LICENSE for copying information.
package httpranger
import (
"bytes"
"context"
"fmt"
"io"
"log"
"net/http"
"strconv"
"storj.io/common/ranger"
)
type httpRanger struct {
URL string
size int64
}
// HTTPRanger turns an HTTP URL into a Ranger.
func HTTPRanger(ctx context.Context, url string) (_ ranger.Ranger, err error) {
defer mon.Task()(&ctx)(&err)
/* #nosec G107 */ // The callers must control the soure of the url value
req, err := http.NewRequestWithContext(ctx, http.MethodHead, url, nil)
if err != nil {
return nil, err
}
resp, err := http.DefaultClient.Do(req)
if err != nil {
return nil, err
}
defer func() {
if err := resp.Body.Close(); err != nil {
log.Printf("Failed to close body: %v", err)
}
}()
if resp.StatusCode != http.StatusOK {
return nil, Error.New("unexpected status code: %d (expected %d)",
resp.StatusCode, http.StatusOK)
}
contentLength := resp.Header.Get("Content-Length")
size, err := strconv.Atoi(contentLength)
if err != nil {
return nil, err
}
return &httpRanger{
URL: url,
size: int64(size),
}, nil
}
// HTTPRangerSize creates an HTTPRanger with known size.
// Use it if you know the content size. This will safe the extra HEAD request
// for retrieving the content size.
func HTTPRangerSize(url string, size int64) ranger.Ranger { //nolint:golint,revive
return &httpRanger{
URL: url,
size: size,
}
}
// Size implements Ranger.Size.
func (r *httpRanger) Size() int64 {
return r.size
}
// Range implements Ranger.Range.
func (r *httpRanger) Range(ctx context.Context, offset, length int64) (_ io.ReadCloser, err error) {
defer mon.Task()(&ctx)(&err)
if offset < 0 {
return nil, Error.New("negative offset")
}
if length < 0 {
return nil, Error.New("negative length")
}
if offset+length > r.size {
return nil, Error.New("range beyond end")
}
if length == 0 {
return io.NopCloser(bytes.NewReader([]byte{})), nil
}
client := &http.Client{}
req, err := http.NewRequestWithContext(ctx, http.MethodGet, r.URL, nil)
if err != nil {
return nil, err
}
req.Header.Add("Range", fmt.Sprintf("bytes=%d-%d", offset, offset+length-1))
resp, err := client.Do(req)
if err != nil {
return nil, err
}
if resp.StatusCode != http.StatusPartialContent {
if err := resp.Body.Close(); err != nil {
return nil, Error.New("Error: (%v) Failed to close Body :: unexpected status code: %d (expected %d)",
err, resp.StatusCode, http.StatusPartialContent)
}
return nil, Error.New("unexpected status code: %d (expected %d)",
resp.StatusCode, http.StatusPartialContent)
}
return resp.Body, nil
}