forked from syncthing/syncthing
/
gui_csrf.go
115 lines (97 loc) · 2.11 KB
/
gui_csrf.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
package main
import (
"bufio"
"crypto/rand"
"encoding/base64"
"fmt"
"net/http"
"os"
"path/filepath"
"strings"
"sync"
"time"
"github.com/calmh/syncthing/osutil"
)
var csrfTokens []string
var csrfMut sync.Mutex
// Check for CSRF token on /rest/ URLs. If a correct one is not given, reject
// the request with 403. For / and /index.html, set a new CSRF cookie if none
// is currently set.
func csrfMiddleware(w http.ResponseWriter, r *http.Request) {
if validAPIKey(r.Header.Get("X-API-Key")) {
return
}
if strings.HasPrefix(r.URL.Path, "/rest/") {
token := r.Header.Get("X-CSRF-Token")
if !validCsrfToken(token) {
http.Error(w, "CSRF Error", 403)
}
} else if r.URL.Path == "/" || r.URL.Path == "/index.html" {
cookie, err := r.Cookie("CSRF-Token")
if err != nil || !validCsrfToken(cookie.Value) {
cookie = &http.Cookie{
Name: "CSRF-Token",
Value: newCsrfToken(),
}
http.SetCookie(w, cookie)
}
}
}
func validCsrfToken(token string) bool {
csrfMut.Lock()
defer csrfMut.Unlock()
for _, t := range csrfTokens {
if t == token {
return true
}
}
return false
}
func newCsrfToken() string {
bs := make([]byte, 30)
_, err := rand.Reader.Read(bs)
if err != nil {
l.Fatalln(err)
}
token := base64.StdEncoding.EncodeToString(bs)
csrfMut.Lock()
csrfTokens = append(csrfTokens, token)
if len(csrfTokens) > 10 {
csrfTokens = csrfTokens[len(csrfTokens)-10:]
}
defer csrfMut.Unlock()
saveCsrfTokens()
return token
}
func saveCsrfTokens() {
name := filepath.Join(confDir, "csrftokens.txt")
tmp := fmt.Sprintf("%s.tmp.%d", name, time.Now().UnixNano())
f, err := os.OpenFile(tmp, os.O_CREATE|os.O_EXCL|os.O_WRONLY, 0644)
if err != nil {
return
}
defer os.Remove(tmp)
for _, t := range csrfTokens {
_, err := fmt.Fprintln(f, t)
if err != nil {
return
}
}
err = f.Close()
if err != nil {
return
}
osutil.Rename(tmp, name)
}
func loadCsrfTokens() {
name := filepath.Join(confDir, "csrftokens.txt")
f, err := os.Open(name)
if err != nil {
return
}
defer f.Close()
s := bufio.NewScanner(f)
for s.Scan() {
csrfTokens = append(csrfTokens, s.Text())
}
}