auth.go
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// Copyright 2014 Manu Martinez-Almeida. All rights reserved.
// Use of this source code is governed by a MIT style
// license that can be found in the LICENSE file.
package gin
import (
"crypto/subtle"
"encoding/base64"
"net/http"
"strconv"
)
// AuthUserKey is the cookie name for user credential in basic auth.
const AuthUserKey = "user"
// Accounts defines a key/value for user/pass list of authorized logins.
type Accounts map[string]string
type authPair struct {
value string
user string
}
type authPairs []authPair
func (a authPairs) searchCredential(authValue string) (string, bool) {
if authValue == "" {
return "", false
}
for _, pair := range a {
if pair.value == authValue {
return pair.user, true
}
}
return "", false
}
// BasicAuthForRealm returns a Basic HTTP Authorization middleware. It takes as arguments a map[string]string where
// the key is the user name and the value is the password, as well as the name of the Realm.
// If the realm is empty, "Authorization Required" will be used by default.
// (see http://tools.ietf.org/html/rfc2617#section-1.2)
func BasicAuthForRealm(accounts Accounts, realm string) HandlerFunc {
if realm == "" {
realm = "Authorization Required"
}
realm = "Basic realm=" + strconv.Quote(realm)
pairs := processAccounts(accounts)
return func(c *Context) {
// Search user in the slice of allowed credentials
user, found := pairs.searchCredential(c.requestHeader("Authorization"))
if !found {
// Credentials doesn't match, we return 401 and abort handlers chain.
c.Header("WWW-Authenticate", realm)
c.AbortWithStatus(http.StatusUnauthorized)
return
}
// The user credentials was found, set user's id to key AuthUserKey in this context, the user's id can be read later using
// c.MustGet(gin.AuthUserKey).
c.Set(AuthUserKey, user)
}
}
// BasicAuth returns a Basic HTTP Authorization middleware. It takes as argument a map[string]string where
// the key is the user name and the value is the password.
func BasicAuth(accounts Accounts) HandlerFunc {
return BasicAuthForRealm(accounts, "")
}
func processAccounts(accounts Accounts) authPairs {
assert1(len(accounts) > 0, "Empty list of authorized credentials")
pairs := make(authPairs, 0, len(accounts))
for user, password := range accounts {
assert1(user != "", "User can not be empty")
value := authorizationHeader(user, password)
pairs = append(pairs, authPair{
value: value,
user: user,
})
}
return pairs
}
func authorizationHeader(user, password string) string {
base := user + ":" + password
return "Basic " + base64.StdEncoding.EncodeToString([]byte(base))
}
func secureCompare(given, actual string) bool {
if subtle.ConstantTimeEq(int32(len(given)), int32(len(actual))) == 1 {
return subtle.ConstantTimeCompare([]byte(given), []byte(actual)) == 1
}
// Securely compare actual to itself to keep constant time, but always return false.
return subtle.ConstantTimeCompare([]byte(actual), []byte(actual)) == 1 && false
}