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// Copyright 2014 The Gogs Authors. All rights reserved.
// Use of this source code is governed by a MIT-style
// license that can be found in the LICENSE file.
// Package captcha a middleware that provides captcha service for Macaron.
package captcha
import (
"fmt"
"html/template"
"net/http"
"path"
"strings"
"github.com/Unknwon/macaron"
"github.com/gogits/cache"
"github.com/gogits/gogs/modules/base"
"github.com/gogits/gogs/modules/log"
)
var (
defaultChars = []byte{0, 1, 2, 3, 4, 5, 6, 7, 8, 9}
)
const (
// default captcha attributes
challengeNums = 6
expiration = 600
fieldIdName = "captcha_id"
fieldCaptchaName = "captcha"
cachePrefix = "captcha_"
defaultURLPrefix = "/captcha/"
)
// Captcha struct
type Captcha struct {
store cache.Cache
// url prefix for captcha image
URLPrefix string
// specify captcha id input field name
FieldIdName string
// specify captcha result input field name
FieldCaptchaName string
// captcha image width and height
StdWidth int
StdHeight int
// captcha chars nums
ChallengeNums int
// captcha expiration seconds
Expiration int64
// cache key prefix
CachePrefix string
}
// generate key string
func (c *Captcha) key(id string) string {
return c.CachePrefix + id
}
// generate rand chars with default chars
func (c *Captcha) genRandChars() []byte {
return base.RandomCreateBytes(c.ChallengeNums, defaultChars...)
}
// beego filter handler for serve captcha image
func (c *Captcha) Handler(ctx *macaron.Context) {
var chars []byte
id := path.Base(ctx.Req.RequestURI)
if i := strings.Index(id, "."); i != -1 {
id = id[:i]
}
key := c.key(id)
if v, ok := c.store.Get(key).([]byte); ok {
chars = v
} else {
ctx.Status(404)
ctx.Write([]byte("captcha not found"))
return
}
// reload captcha
if len(ctx.Query("reload")) > 0 {
chars = c.genRandChars()
if err := c.store.Put(key, chars, c.Expiration); err != nil {
ctx.Status(500)
ctx.Write([]byte("captcha reload error"))
log.Error(4, "Reload Create Captcha Error: %v", err)
return
}
}
img := NewImage(chars, c.StdWidth, c.StdHeight)
if _, err := img.WriteTo(ctx.RW()); err != nil {
log.Error(4, "Write Captcha Image Error: %v", err)
}
}
// tempalte func for output html
func (c *Captcha) CreateCaptchaHtml() template.HTML {
value, err := c.CreateCaptcha()
if err != nil {
log.Error(4, "Create Captcha Error: %v", err)
return ""
}
// create html
return template.HTML(fmt.Sprintf(`<input type="hidden" name="%s" value="%s">`+
`<a class="captcha" href="javascript:">`+
`<img onclick="this.src=('%s%s.png?reload='+(new Date()).getTime())" class="captcha-img" src="%s%s.png">`+
`</a>`, c.FieldIdName, value, c.URLPrefix, value, c.URLPrefix, value))
}
// create a new captcha id
func (c *Captcha) CreateCaptcha() (string, error) {
// generate captcha id
id := string(base.RandomCreateBytes(15))
// get the captcha chars
chars := c.genRandChars()
// save to store
if err := c.store.Put(c.key(id), chars, c.Expiration); err != nil {
return "", err
}
return id, nil
}
// verify from a request
func (c *Captcha) VerifyReq(req *http.Request) bool {
req.ParseForm()
return c.Verify(req.Form.Get(c.FieldIdName), req.Form.Get(c.FieldCaptchaName))
}
// direct verify id and challenge string
func (c *Captcha) Verify(id string, challenge string) (success bool) {
if len(challenge) == 0 || len(id) == 0 {
return
}
var chars []byte
key := c.key(id)
if v, ok := c.store.Get(key).([]byte); ok && len(v) == len(challenge) {
chars = v
} else {
return
}
defer func() {
// finally remove it
c.store.Delete(key)
}()
// verify challenge
for i, c := range chars {
if c != challenge[i]-48 {
return
}
}
return true
}
// create a new captcha.Captcha
func NewCaptcha(urlPrefix string, store cache.Cache) *Captcha {
cpt := &Captcha{}
cpt.store = store
cpt.FieldIdName = fieldIdName
cpt.FieldCaptchaName = fieldCaptchaName
cpt.ChallengeNums = challengeNums
cpt.Expiration = expiration
cpt.CachePrefix = cachePrefix
cpt.StdWidth = stdWidth
cpt.StdHeight = stdHeight
if len(urlPrefix) == 0 {
urlPrefix = defaultURLPrefix
}
if urlPrefix[len(urlPrefix)-1] != '/' {
urlPrefix += "/"
}
cpt.URLPrefix = urlPrefix
base.TemplateFuncs["CreateCaptcha"] = cpt.CreateCaptchaHtml
return cpt
}
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