storj/pkg/ranger/http.go
2018-06-19 18:59:09 +03:00

89 lines
2.0 KiB
Go

// Copyright (C) 2018 Storj Labs, Inc.
// See LICENSE for copying information.
package ranger
import (
"bytes"
"context"
"fmt"
"io"
"io/ioutil"
"net/http"
"strconv"
)
type httpRanger struct {
URL string
size int64
}
// HTTPRanger turns an HTTP URL into a Ranger
func HTTPRanger(URL string) (Ranger, error) {
resp, err := http.Head(URL)
if err != nil {
return nil, err
}
defer resp.Body.Close()
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 {
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, error) {
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 ioutil.NopCloser(bytes.NewReader([]byte{})), nil
}
client := &http.Client{}
req, err := http.NewRequest("GET", 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 {
resp.Body.Close()
return nil, Error.New("unexpected status code: %d (expected %d)",
resp.StatusCode, http.StatusPartialContent)
}
return resp.Body, nil
}