Added all required dependencies

vendor/github.com/go-macaron/csrf/xsrf.go

@@ -0,0 +1,97 @@
+// Copyright 2012 Google Inc. All Rights Reserved.
+// Copyright 2014 The Macaron Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package csrf
+
+import (
+	"bytes"
+	"crypto/hmac"
+	"crypto/sha1"
+	"crypto/subtle"
+	"encoding/base64"
+	"fmt"
+	"strconv"
+	"strings"
+	"time"
+)
+
+// The duration that 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)
+}
+
+// GenerateToken returns a URL-safe secure XSRF token that expires in 24 hours.
+//
+// key is a secret key for your application.
+// userID is a unique identifier for the user.
+// actionID is the action the user is taking (e.g. POSTing to a particular path).
+func GenerateToken(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 {
+	h := hmac.New(sha1.New, []byte(key))
+	fmt.Fprintf(h, "%s:%s:%d", clean(userID), clean(actionID), now.UnixNano())
+	tok := fmt.Sprintf("%s:%d", h.Sum(nil), now.UnixNano())
+	return base64.URLEncoding.EncodeToString([]byte(tok))
+}
+
+// Valid returns true if token is a valid, unexpired token returned by Generate.
+func ValidToken(token, key, userID, actionID string) bool {
+	return validTokenAtTime(token, key, userID, actionID, time.Now())
+}
+
+// validTokenAtTime is like Valid, but it uses now to check if the token is expired.
+func validTokenAtTime(token, key, userID, actionID string, now time.Time) bool {
+	// Decode the token.
+	data, err := base64.URLEncoding.DecodeString(token)
+	if err != nil {
+		return false
+	}
+
+	// Extract the issue time of the token.
+	sep := bytes.LastIndex(data, []byte{':'})
+	if sep < 0 {
+		return false
+	}
+	nanos, err := strconv.ParseInt(string(data[sep+1:]), 10, 64)
+	if err != nil {
+		return false
+	}
+	issueTime := time.Unix(0, nanos)
+
+	// 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
+}