308 lines
8.6 KiB
Go
308 lines
8.6 KiB
Go
// Copyright 2013 Martini Authors
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// Copyright 2014 The Macaron Authors
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// Copyright 2021 The Gitea Authors
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//
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// Licensed under the Apache License, Version 2.0 (the "License"): you may
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// not use this file except in compliance with the License. You may obtain
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// a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
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// WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
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// License for the specific language governing permissions and limitations
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// under the License.
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// a middleware that generates and validates CSRF tokens.
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package context
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import (
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"encoding/base32"
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"fmt"
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"net/http"
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"time"
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"code.gitea.io/gitea/modules/setting"
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"code.gitea.io/gitea/modules/util"
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"code.gitea.io/gitea/modules/web/middleware"
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)
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// CSRF represents a CSRF service and is used to get the current token and validate a suspect token.
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type CSRF interface {
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// Return HTTP header to search for token.
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GetHeaderName() string
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// Return form value to search for token.
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GetFormName() string
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// Return cookie name to search for token.
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GetCookieName() string
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// Return cookie path
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GetCookiePath() string
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// Return the flag value used for the csrf token.
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GetCookieHTTPOnly() bool
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// Return cookie domain
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GetCookieDomain() string
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// Return the token.
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GetToken() string
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// Validate by token.
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ValidToken(t string) bool
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// Error replies to the request with a custom function when ValidToken fails.
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Error(w http.ResponseWriter)
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}
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type csrf struct {
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// Header name value for setting and getting csrf token.
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Header string
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// Form name value for setting and getting csrf token.
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Form string
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// Cookie name value for setting and getting csrf token.
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Cookie string
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// Cookie domain
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CookieDomain string
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// Cookie path
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CookiePath string
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// Cookie HttpOnly flag value used for the csrf token.
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CookieHTTPOnly bool
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// Token generated to pass via header, cookie, or hidden form value.
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Token string
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// This value must be unique per user.
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ID string
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// Secret used along with the unique id above to generate the Token.
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Secret string
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// ErrorFunc is the custom function that replies to the request when ValidToken fails.
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ErrorFunc func(w http.ResponseWriter)
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}
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// GetHeaderName returns the name of the HTTP header for csrf token.
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func (c *csrf) GetHeaderName() string {
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return c.Header
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}
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// GetFormName returns the name of the form value for csrf token.
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func (c *csrf) GetFormName() string {
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return c.Form
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}
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// GetCookieName returns the name of the cookie for csrf token.
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func (c *csrf) GetCookieName() string {
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return c.Cookie
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}
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// GetCookiePath returns the path of the cookie for csrf token.
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func (c *csrf) GetCookiePath() string {
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return c.CookiePath
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}
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// GetCookieHTTPOnly returns the flag value used for the csrf token.
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func (c *csrf) GetCookieHTTPOnly() bool {
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return c.CookieHTTPOnly
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}
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// GetCookieDomain returns the flag value used for the csrf token.
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func (c *csrf) GetCookieDomain() string {
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return c.CookieDomain
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}
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// GetToken returns the current token. This is typically used
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// to populate a hidden form in an HTML template.
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func (c *csrf) GetToken() string {
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return c.Token
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}
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// ValidToken validates the passed token against the existing Secret and ID.
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func (c *csrf) ValidToken(t string) bool {
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return ValidToken(t, c.Secret, c.ID, "POST")
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}
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// Error replies to the request when ValidToken fails.
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func (c *csrf) Error(w http.ResponseWriter) {
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c.ErrorFunc(w)
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}
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// CsrfOptions maintains options to manage behavior of Generate.
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type CsrfOptions struct {
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// The global secret value used to generate Tokens.
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Secret string
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// HTTP header used to set and get token.
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Header string
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// Form value used to set and get token.
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Form string
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// Cookie value used to set and get token.
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Cookie string
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// Cookie domain.
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CookieDomain string
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// Cookie path.
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CookiePath string
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CookieHTTPOnly bool
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// SameSite set the cookie SameSite type
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SameSite http.SameSite
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// Key used for getting the unique ID per user.
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SessionKey string
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// oldSessionKey saves old value corresponding to SessionKey.
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oldSessionKey string
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// If true, send token via X-CSRFToken header.
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SetHeader bool
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// If true, send token via _csrf cookie.
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SetCookie bool
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// Set the Secure flag to true on the cookie.
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Secure bool
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// Disallow Origin appear in request header.
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Origin bool
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// The function called when Validate fails.
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ErrorFunc func(w http.ResponseWriter)
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// Cookie life time. Default is 0
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CookieLifeTime int
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}
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func prepareOptions(options []CsrfOptions) CsrfOptions {
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var opt CsrfOptions
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if len(options) > 0 {
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opt = options[0]
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}
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// Defaults.
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if len(opt.Secret) == 0 {
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randBytes, err := util.CryptoRandomBytes(8)
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if err != nil {
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// this panic can be handled by the recover() in http handlers
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panic(fmt.Errorf("failed to generate random bytes: %w", err))
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}
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opt.Secret = base32.StdEncoding.EncodeToString(randBytes)
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}
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if len(opt.Header) == 0 {
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opt.Header = "X-CSRFToken"
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}
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if len(opt.Form) == 0 {
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opt.Form = "_csrf"
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}
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if len(opt.Cookie) == 0 {
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opt.Cookie = "_csrf"
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}
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if len(opt.CookiePath) == 0 {
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opt.CookiePath = "/"
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}
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if len(opt.SessionKey) == 0 {
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opt.SessionKey = "uid"
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}
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opt.oldSessionKey = "_old_" + opt.SessionKey
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if opt.ErrorFunc == nil {
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opt.ErrorFunc = func(w http.ResponseWriter) {
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http.Error(w, "Invalid csrf token.", http.StatusBadRequest)
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}
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}
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return opt
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}
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// Csrfer maps CSRF to each request. If this request is a Get request, it will generate a new token.
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// Additionally, depending on options set, generated tokens will be sent via Header and/or Cookie.
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func Csrfer(opt CsrfOptions, ctx *Context) CSRF {
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opt = prepareOptions([]CsrfOptions{opt})
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x := &csrf{
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Secret: opt.Secret,
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Header: opt.Header,
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Form: opt.Form,
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Cookie: opt.Cookie,
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CookieDomain: opt.CookieDomain,
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CookiePath: opt.CookiePath,
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CookieHTTPOnly: opt.CookieHTTPOnly,
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ErrorFunc: opt.ErrorFunc,
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}
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if opt.Origin && len(ctx.Req.Header.Get("Origin")) > 0 {
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return x
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}
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x.ID = "0"
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uid := ctx.Session.Get(opt.SessionKey)
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if uid != nil {
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x.ID = util.ToStr(uid)
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}
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needsNew := false
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oldUID := ctx.Session.Get(opt.oldSessionKey)
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if oldUID == nil || oldUID.(string) != x.ID {
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needsNew = true
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_ = ctx.Session.Set(opt.oldSessionKey, x.ID)
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} else {
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// If cookie present, map existing token, else generate a new one.
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if val := ctx.GetCookie(opt.Cookie); len(val) > 0 {
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// FIXME: test coverage.
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x.Token = val
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} else {
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needsNew = true
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}
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}
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if needsNew {
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// FIXME: actionId.
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x.Token = GenerateToken(x.Secret, x.ID, "POST")
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if opt.SetCookie {
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var expires interface{}
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if opt.CookieLifeTime == 0 {
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expires = time.Now().AddDate(0, 0, 1)
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}
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middleware.SetCookie(ctx.Resp, opt.Cookie, x.Token,
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opt.CookieLifeTime,
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opt.CookiePath,
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opt.CookieDomain,
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opt.Secure,
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opt.CookieHTTPOnly,
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expires,
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middleware.SameSite(opt.SameSite),
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)
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}
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}
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if opt.SetHeader {
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ctx.Resp.Header().Add(opt.Header, x.Token)
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}
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return x
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}
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// Validate should be used as a per route middleware. It attempts to get a token from a "X-CSRFToken"
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// HTTP header and then a "_csrf" form value. If one of these is found, the token will be validated
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// using ValidToken. If this validation fails, custom Error is sent in the reply.
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// If neither a header or form value is found, http.StatusBadRequest is sent.
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func Validate(ctx *Context, x CSRF) {
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if token := ctx.Req.Header.Get(x.GetHeaderName()); len(token) > 0 {
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if !x.ValidToken(token) {
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// Delete the cookie
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middleware.SetCookie(ctx.Resp, x.GetCookieName(), "",
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-1,
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x.GetCookiePath(),
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x.GetCookieDomain()) // FIXME: Do we need to set the Secure, httpOnly and SameSite values too?
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if middleware.IsAPIPath(ctx.Req) {
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x.Error(ctx.Resp)
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return
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}
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ctx.Flash.Error(ctx.Tr("error.invalid_csrf"))
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ctx.Redirect(setting.AppSubURL + "/")
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}
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return
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}
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if token := ctx.Req.FormValue(x.GetFormName()); len(token) > 0 {
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if !x.ValidToken(token) {
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// Delete the cookie
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middleware.SetCookie(ctx.Resp, x.GetCookieName(), "",
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-1,
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x.GetCookiePath(),
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x.GetCookieDomain()) // FIXME: Do we need to set the Secure, httpOnly and SameSite values too?
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if middleware.IsAPIPath(ctx.Req) {
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x.Error(ctx.Resp)
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return
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}
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ctx.Flash.Error(ctx.Tr("error.invalid_csrf"))
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ctx.Redirect(setting.AppSubURL + "/")
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}
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return
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}
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if middleware.IsAPIPath(ctx.Req) {
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http.Error(ctx.Resp, "Bad Request: no CSRF token present", http.StatusBadRequest)
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return
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}
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ctx.Flash.Error(ctx.Tr("error.missing_csrf"))
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ctx.Redirect(setting.AppSubURL + "/")
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}
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