refactor: move go-chi/captcha into Gitea (#39529)

The `gitea.com/go-chi/captcha` package only exists for Gitea,
so it moves into `modules/imagecaptcha`.

- Reloading an expired challenge shows a new image instead of a broken one
- Every answer is consumed on its first check
- OpenID registration stops after a failed captcha

---------

Co-authored-by: wxiaoguang <wxiaoguang@gmail.com>

routers/web/auth/auth.go

@@ -19,6 +19,7 @@ import (
 	user_model "gitea.dev/models/user"
 	"gitea.dev/modules/auth/password"
 	"gitea.dev/modules/httplib"
+	"gitea.dev/modules/imagecaptcha"
 	"gitea.dev/modules/log"
 	"gitea.dev/modules/optional"
 	"gitea.dev/modules/session"
@@ -70,7 +71,7 @@ func prepareCommonAuthPageData(ctx *context.Context, opt CommonAuthOptions) {
 		ctx.Data["McaptchaURL"] = strings.TrimSuffix(setting.Service.McaptchaURL, "/")
 		ctx.Data["CfTurnstileSitekey"] = setting.Service.CfTurnstileSitekey
 		if setting.Service.CaptchaType == setting.ImageCaptcha {
-			ctx.Data["Captcha"] = context.GetImageCaptcha()
+			ctx.Data["CreateImageCaptcha"] = imagecaptcha.CreateNew
 		}
 	}
 }
@@ -298,8 +299,7 @@ func SignInPost(ctx *context.Context) {
 	form := web.GetForm[*forms.SignInForm](ctx)
 
 	if setting.Service.EnableCaptcha && setting.Service.RequireCaptchaForLogin {
-		context.VerifyCaptcha(ctx, tplSignIn, form)
-		if ctx.Written() {
+		if !context.VerifyCaptcha(ctx, tplSignIn, form) {
 			return
 		}
 	}
@@ -553,8 +553,7 @@ func SignUpPost(ctx *context.Context) {
 		return
 	}
 
-	context.VerifyCaptcha(ctx, tplSignUp, form)
-	if ctx.Written() {
+	if !context.VerifyCaptcha(ctx, tplSignUp, form) {
 		return
 	}
 

routers/web/auth/auth_test.go

@@ -17,8 +17,10 @@ import (
 	"gitea.dev/modules/setting"
 	"gitea.dev/modules/test"
 	"gitea.dev/modules/util"
+	"gitea.dev/modules/web"
 	"gitea.dev/services/auth/source/oauth2"
 	"gitea.dev/services/contexttest"
+	"gitea.dev/services/forms"
 
 	"github.com/markbates/goth"
 	"github.com/markbates/goth/gothic"
@@ -199,3 +201,18 @@ func TestOpenIDRequireTwoFactor(t *testing.T) {
 	openIDRequireTwoFactor(ctx, user2, false, "https://example.com/id")
 	assert.False(t, ctx.Written())
 }
+
+func TestRegisterOpenIDPostRejectsWrongCaptcha(t *testing.T) {
+	require.NoError(t, unittest.PrepareTestDatabase())
+	defer test.MockVariableValue(&setting.Service.EnableCaptcha, true)()
+	defer test.MockVariableValue(&setting.Service.CaptchaType, setting.ImageCaptcha)()
+	sess := session.NewMockMemStore("dummy-sid-openid-register")
+	require.NoError(t, sess.Set("openid_verified_uri", "https://example.com/openid"))
+
+	ctx, _ := contexttest.MockContext(t, "POST /user/openid/register", contexttest.MockContextOption{SessionStore: sess})
+	contexttest.MockRequestPostForm(ctx.Req, url.Values{"captcha_id": {"unknown"}, "captcha": {"000000"}})
+	web.SetForm(ctx, &forms.SignUpOpenIDForm{UserName: "openid-captcha-user", Email: "openid-captcha-user@example.com"})
+	RegisterOpenIDPost(ctx)
+	assert.Equal(t, true, ctx.Data["Err_Captcha"])
+	unittest.AssertNotExistsBean(t, &user_model.User{LowerName: "openid-captcha-user"})
+}

routers/web/auth/linkaccount.go

@@ -38,6 +38,7 @@ func prepareLinkAccountPageData(ctx *context.Context) {
 	ctx.Data["ShowRegistrationButton"] = false
 	ctx.Data["DisableRegistration"] = setting.Service.DisableRegistration
 
+	// FIXME: this logic is not right: captcha is enabled, but LinkAccountPostSignIn never checks for captcha
 	prepareCommonAuthPageData(ctx, CommonAuthOptions{
 		EnableCaptcha: setting.Service.EnableCaptcha && setting.Service.RequireExternalRegistrationCaptcha,
 	})
@@ -198,8 +199,7 @@ func LinkAccountPostRegister(ctx *context.Context) {
 	}
 
 	if setting.Service.EnableCaptcha && setting.Service.RequireExternalRegistrationCaptcha {
-		context.VerifyCaptcha(ctx, tplLinkAccount, form)
-		if ctx.Written() {
+		if !context.VerifyCaptcha(ctx, tplLinkAccount, form) {
 			return
 		}
 	}

routers/web/auth/openid.go

@@ -378,7 +378,9 @@ func RegisterOpenIDPost(ctx *context.Context) {
 			ctx.ServerError("", err)
 			return
 		}
-		context.VerifyCaptcha(ctx, tplSignUpOID, form)
+		if !context.VerifyCaptcha(ctx, tplSignUpOID, form) {
+			return
+		}
 	}
 
 	length := max(setting.MinPasswordLength, 256)