/
httpfile.go
222 lines (208 loc) · 4.21 KB
/
httpfile.go
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
package httpfile
import (
"bytes"
"errors"
"fmt"
"io"
"net/http"
"os"
"strconv"
"github.com/ipfs/go-ipfs/Godeps/_workspace/src/github.com/anacrolix/missinggo"
)
type File struct {
off int64
r io.ReadCloser
rOff int64
length int64
url string
}
func OpenSectionReader(url string, off, n int64) (ret io.ReadCloser, err error) {
req, err := http.NewRequest("GET", url, nil)
if err != nil {
return
}
req.Header.Set("Range", fmt.Sprintf("bytes=%d-%d", off, off+n-1))
resp, err := http.DefaultClient.Do(req)
if err != nil {
return
}
if resp.StatusCode == http.StatusNotFound {
err = ErrNotFound
resp.Body.Close()
return
}
if resp.StatusCode != http.StatusPartialContent {
err = fmt.Errorf("bad response status: %s", resp.Status)
resp.Body.Close()
return
}
ret = resp.Body
return
}
func Open(url string) *File {
return &File{
url: url,
}
}
func (me *File) prepareReader() (err error) {
if me.r != nil && me.off != me.rOff {
me.r.Close()
me.r = nil
}
if me.r != nil {
return nil
}
req, err := http.NewRequest("GET", me.url, nil)
if err != nil {
return
}
if me.off != 0 {
req.Header.Set("Range", fmt.Sprintf("bytes=%d-", me.off))
}
resp, err := http.DefaultClient.Do(req)
if err != nil {
return
}
switch resp.StatusCode {
case http.StatusPartialContent:
cr, ok := missinggo.ParseHTTPBytesContentRange(resp.Header.Get("Content-Range"))
if !ok || cr.First != me.off {
err = errors.New("bad response")
resp.Body.Close()
return
}
me.length = cr.Length
case http.StatusOK:
if me.off != 0 {
err = errors.New("bad response")
resp.Body.Close()
return
}
if h := resp.Header.Get("Content-Length"); h != "" {
var cl uint64
cl, err = strconv.ParseUint(h, 10, 64)
if err != nil {
resp.Body.Close()
return
}
me.length = int64(cl)
}
default:
err = errors.New(resp.Status)
resp.Body.Close()
return
}
me.r = resp.Body
me.rOff = me.off
return
}
func (me *File) Read(b []byte) (n int, err error) {
err = me.prepareReader()
if err != nil {
return
}
n, err = me.r.Read(b)
me.off += int64(n)
me.rOff += int64(n)
return
}
func instanceLength(r *http.Response) (int64, error) {
switch r.StatusCode {
case http.StatusOK:
if h := r.Header.Get("Content-Length"); h != "" {
return strconv.ParseInt(h, 10, 64)
} else {
return -1, nil
}
case http.StatusPartialContent:
cr, ok := missinggo.ParseHTTPBytesContentRange(r.Header.Get("Content-Range"))
if !ok {
return -1, errors.New("bad 206 response")
}
return cr.Length, nil
default:
return -1, errors.New(r.Status)
}
}
func (me *File) Seek(offset int64, whence int) (ret int64, err error) {
switch whence {
case os.SEEK_SET:
ret = offset
case os.SEEK_CUR:
ret = me.off + offset
case os.SEEK_END:
if me.length < 0 {
err = errors.New("length unknown")
return
}
ret = me.length + offset
default:
err = fmt.Errorf("unhandled whence: %d", whence)
return
}
me.off = ret
return
}
func (me *File) Write(b []byte) (n int, err error) {
req, err := http.NewRequest("PATCH", me.url, bytes.NewReader(b))
if err != nil {
return
}
req.Header.Set("Content-Range", fmt.Sprintf("bytes=%d-", me.off))
req.ContentLength = int64(len(b))
resp, err := http.DefaultClient.Do(req)
if err != nil {
return
}
resp.Body.Close()
if resp.StatusCode != http.StatusPartialContent {
err = errors.New(resp.Status)
return
}
n = len(b)
me.off += int64(n)
return
}
var (
ErrNotFound = errors.New("not found")
)
// Returns the length of the resource in bytes.
func GetLength(url string) (ret int64, err error) {
resp, err := http.Head(url)
if err != nil {
return
}
resp.Body.Close()
if resp.StatusCode == http.StatusNotFound {
err = ErrNotFound
return
}
return instanceLength(resp)
}
func (me *File) Close() error {
me.url = ""
if me.r != nil {
me.r.Close()
me.r = nil
}
return nil
}
func Delete(urlStr string) (err error) {
req, err := http.NewRequest("DELETE", urlStr, nil)
if err != nil {
return
}
resp, err := http.DefaultClient.Do(req)
if err != nil {
return
}
resp.Body.Close()
if resp.StatusCode == http.StatusNotFound {
err = ErrNotFound
return
}
if resp.StatusCode != 200 {
err = fmt.Errorf("response: %s", resp.Status)
}
return
}