162 lines
3.9 KiB
Go
162 lines
3.9 KiB
Go
// Copyright 2021 Flamego. All rights reserved.
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// Use of this source code is governed by a MIT-style
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// license that can be found in the LICENSE file.
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package captcha
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import (
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"fmt"
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"html/template"
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"image/color"
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"net/http"
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"reflect"
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"strings"
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"github.com/flamego/flamego"
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"github.com/flamego/flamego/inject"
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"github.com/flamego/session"
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"github.com/flamego/captcha/internal/captchautil"
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)
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// Captcha represents a captcha service and is used to validate text in captcha
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// images.
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type Captcha interface {
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// HTML returns the HTML content to display and refresh captcha images.
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HTML() template.HTML
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// ValidText validates the passed text against the secret text.
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ValidText(t string) bool
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}
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var _ Captcha = (*captcha)(nil)
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type captcha struct {
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session session.Session
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urlPrefix string
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}
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func (c *captcha) HTML() template.HTML {
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return template.HTML(
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fmt.Sprintf(`
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<a class="captcha" href="javascript:" tabindex="-1">
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<img onclick="this.src=('%[1]simage.jpeg?refresh=true')" src="%[1]simage.jpeg">
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</a>`,
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c.urlPrefix),
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)
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}
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const textKey = "flamego::captcha::text"
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func (c *captcha) ValidText(t string) bool {
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defer c.session.Delete(textKey)
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want, ok := c.session.Get(textKey).(string)
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if !ok {
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return false
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}
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return strings.EqualFold(want, t)
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}
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// Options contains options for the captcha.Captchaer middleware.
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type Options struct {
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// URLPrefix is the URL path prefix for serving captcha images. Default is
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// "/.captcha/".
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URLPrefix string
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// TextLength is the length of text to be generated in captcha images. Default
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// is 4.
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TextLength int
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// Width is the image width of captcha. Default is 240.
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Width int
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// Height is the image height of captcha. Default is 80.
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Height int
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// DPI is the image DPI of captcha. Default is 72.
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DPI int
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}
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var _ inject.FastInvoker = (*captchaInvoker)(nil)
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// captchaInvoker is an inject.FastInvoker implementation of
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// `func(flamego.Context, session.Session)`.
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type captchaInvoker func(flamego.Context, session.Session)
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func (invoke captchaInvoker) Invoke(args []interface{}) ([]reflect.Value, error) {
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invoke(args[0].(flamego.Context), args[1].(session.Session))
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return nil, nil
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}
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// Captchaer returns a middleware handler that injects captcha.Captcha into the
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// request context, which is used for generating and validating text in captcha
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// images.
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func Captchaer(opts ...Options) flamego.Handler {
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var opt Options
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if len(opts) > 0 {
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opt = opts[0]
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}
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parseOptions := func(opts Options) Options {
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if opts.URLPrefix == "" {
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opts.URLPrefix = "/.captcha/"
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}
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if opts.TextLength <= 0 {
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opts.TextLength = 4
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}
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if opts.Width <= 0 {
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opts.Width = 240
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}
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if opts.Height <= 0 {
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opts.Height = 80
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}
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if opts.DPI <= 0 {
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opts.DPI = 72
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}
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return opts
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}
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opt = parseOptions(opt)
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return captchaInvoker(func(c flamego.Context, s session.Session) {
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cpt := &captcha{
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session: s,
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urlPrefix: opt.URLPrefix,
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}
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c.MapTo(cpt, (*Captcha)(nil))
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if !strings.HasPrefix(c.Request().URL.Path, opt.URLPrefix) {
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return
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}
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text, ok := s.Get(textKey).(string)
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if !ok || c.QueryBool("refresh") {
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var err error
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text, err = captchautil.RandomText(opt.TextLength)
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if err != nil {
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panic("captcha: generate random text: " + err.Error())
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}
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s.Set(textKey, text)
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}
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img, err := captchautil.CreateImage(
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opt.Width, opt.Height, opt.DPI, captchautil.RandomLightColor(),
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captchautil.Noise(captchautil.ComplexityLow),
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captchautil.TextNoise(captchautil.ComplexityLow),
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captchautil.Text(text),
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captchautil.Curve(),
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captchautil.Border(
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color.RGBA{R: 170, G: 170, B: 170, A: 255},
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),
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)
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if err != nil {
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panic("captcha: create image: " + err.Error())
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}
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c.ResponseWriter().Header().Set("Cache-Control", "no-store")
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c.ResponseWriter().WriteHeader(http.StatusOK)
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err = img.Encode(c.ResponseWriter())
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if err != nil {
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panic("captcha: encode image: " + err.Error())
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}
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})
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}
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