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Diffstat (limited to 'vendor/golang.org/x/net/xsrftoken/xsrf.go')
-rw-r--r--vendor/golang.org/x/net/xsrftoken/xsrf.go94
1 files changed, 94 insertions, 0 deletions
diff --git a/vendor/golang.org/x/net/xsrftoken/xsrf.go b/vendor/golang.org/x/net/xsrftoken/xsrf.go
new file mode 100644
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+++ b/vendor/golang.org/x/net/xsrftoken/xsrf.go
@@ -0,0 +1,94 @@
+// Copyright 2012 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// Package xsrftoken provides methods for generating and validating secure XSRF tokens.
+package xsrftoken // import "golang.org/x/net/xsrftoken"
+
+import (
+ "crypto/hmac"
+ "crypto/sha1"
+ "crypto/subtle"
+ "encoding/base64"
+ "fmt"
+ "strconv"
+ "strings"
+ "time"
+)
+
+// Timeout is the duration for which XSRF tokens are valid.
+// It is exported so clients may set cookie timeouts that match generated tokens.
+const Timeout = 24 * time.Hour
+
+// clean sanitizes a string for inclusion in a token by replacing all ":"s.
+func clean(s string) string {
+ return strings.Replace(s, ":", "_", -1)
+}
+
+// Generate returns a URL-safe secure XSRF token that expires in 24 hours.
+//
+// key is a secret key for your application; it must be non-empty.
+// userID is an optional unique identifier for the user.
+// actionID is an optional action the user is taking (e.g. POSTing to a particular path).
+func Generate(key, userID, actionID string) string {
+ return generateTokenAtTime(key, userID, actionID, time.Now())
+}
+
+// generateTokenAtTime is like Generate, but returns a token that expires 24 hours from now.
+func generateTokenAtTime(key, userID, actionID string, now time.Time) string {
+ if len(key) == 0 {
+ panic("zero length xsrf secret key")
+ }
+ // Round time up and convert to milliseconds.
+ milliTime := (now.UnixNano() + 1e6 - 1) / 1e6
+
+ h := hmac.New(sha1.New, []byte(key))
+ fmt.Fprintf(h, "%s:%s:%d", clean(userID), clean(actionID), milliTime)
+
+ // Get the padded base64 string then removing the padding.
+ tok := string(h.Sum(nil))
+ tok = base64.URLEncoding.EncodeToString([]byte(tok))
+ tok = strings.TrimRight(tok, "=")
+
+ return fmt.Sprintf("%s:%d", tok, milliTime)
+}
+
+// Valid reports whether a token is a valid, unexpired token returned by Generate.
+func Valid(token, key, userID, actionID string) bool {
+ return validTokenAtTime(token, key, userID, actionID, time.Now())
+}
+
+// validTokenAtTime reports whether a token is valid at the given time.
+func validTokenAtTime(token, key, userID, actionID string, now time.Time) bool {
+ if len(key) == 0 {
+ panic("zero length xsrf secret key")
+ }
+ // Extract the issue time of the token.
+ sep := strings.LastIndex(token, ":")
+ if sep < 0 {
+ return false
+ }
+ millis, err := strconv.ParseInt(token[sep+1:], 10, 64)
+ if err != nil {
+ return false
+ }
+ issueTime := time.Unix(0, millis*1e6)
+
+ // Check that the token is not expired.
+ if now.Sub(issueTime) >= Timeout {
+ return false
+ }
+
+ // Check that the token is not from the future.
+ // Allow 1 minute grace period in case the token is being verified on a
+ // machine whose clock is behind the machine that issued the token.
+ if issueTime.After(now.Add(1 * time.Minute)) {
+ return false
+ }
+
+ expected := generateTokenAtTime(key, userID, actionID, issueTime)
+
+ // Check that the token matches the expected value.
+ // Use constant time comparison to avoid timing attacks.
+ return subtle.ConstantTimeCompare([]byte(token), []byte(expected)) == 1
+}