Fix URLJoin, markup render link reoslving, sign-in/up/linkaccount page common data (#36861)

The logic of "URLJoin" is unclear and it is often abused.

Also:
* Correct the `resolveLinkRelative` behavior
* Fix missing "PathEscape" in `ToTag`
* Fix more FIXMEs, and add new FIXMEs for newly found problems
* Refactor "auth page common template data"

routers/web/auth/openid.go

@@ -229,19 +229,26 @@ func signInOpenIDVerify(ctx *context.Context) {
 	}
 }
 
-// ConnectOpenID shows a form to connect an OpenID URI to an existing account
-func ConnectOpenID(ctx *context.Context) {
-	oid, _ := ctx.Session.Get("openid_verified_uri").(string)
+func prepareConnectOpenIDPageData(ctx *context.Context) (oid string) {
+	oid, _ = ctx.Session.Get("openid_verified_uri").(string)
 	if oid == "" {
 		ctx.Redirect(setting.AppSubURL + "/user/login/openid")
-		return
+		return ""
 	}
 	ctx.Data["Title"] = "OpenID connect"
 	ctx.Data["PageIsSignIn"] = true
 	ctx.Data["PageIsOpenIDConnect"] = true
-	ctx.Data["EnableOpenIDSignUp"] = setting.Service.EnableOpenIDSignUp
-	ctx.Data["AllowOnlyInternalRegistration"] = setting.Service.AllowOnlyInternalRegistration
 	ctx.Data["OpenID"] = oid
+	prepareCommonAuthPageData(ctx, CommonAuthOptions{EnableCaptcha: false})
+	return oid
+}
+
+// ConnectOpenID shows a form to connect an OpenID URI to an existing account
+func ConnectOpenID(ctx *context.Context) {
+	oid := prepareConnectOpenIDPageData(ctx)
+	if oid == "" {
+		return
+	}
 	userName, _ := ctx.Session.Get("openid_determined_username").(string)
 	if userName != "" {
 		ctx.Data["user_name"] = userName
@@ -252,16 +259,10 @@ func ConnectOpenID(ctx *context.Context) {
 // ConnectOpenIDPost handles submission of a form to connect an OpenID URI to an existing account
 func ConnectOpenIDPost(ctx *context.Context) {
 	form := web.GetForm(ctx).(*forms.ConnectOpenIDForm)
-	oid, _ := ctx.Session.Get("openid_verified_uri").(string)
+	oid := prepareConnectOpenIDPageData(ctx)
 	if oid == "" {
-		ctx.Redirect(setting.AppSubURL + "/user/login/openid")
 		return
 	}
-	ctx.Data["Title"] = "OpenID connect"
-	ctx.Data["PageIsSignIn"] = true
-	ctx.Data["PageIsOpenIDConnect"] = true
-	ctx.Data["EnableOpenIDSignUp"] = setting.Service.EnableOpenIDSignUp
-	ctx.Data["OpenID"] = oid
 
 	u, _, err := auth.UserSignIn(ctx, form.UserName, form.Password)
 	if err != nil {
@@ -287,28 +288,29 @@ func ConnectOpenIDPost(ctx *context.Context) {
 	handleSignIn(ctx, u, remember)
 }
 
-// RegisterOpenID shows a form to create a new user authenticated via an OpenID URI
-func RegisterOpenID(ctx *context.Context) {
-	oid, _ := ctx.Session.Get("openid_verified_uri").(string)
+func prepareRegisterOpenIDPageData(ctx *context.Context) (oid string) {
+	oid, _ = ctx.Session.Get("openid_verified_uri").(string)
 	if oid == "" {
 		ctx.Redirect(setting.AppSubURL + "/user/login/openid")
-		return
+		return ""
 	}
 	ctx.Data["Title"] = "OpenID signup"
 	ctx.Data["PageIsSignIn"] = true
 	ctx.Data["PageIsOpenIDRegister"] = true
-	ctx.Data["EnableOpenIDSignUp"] = setting.Service.EnableOpenIDSignUp
-	ctx.Data["AllowOnlyInternalRegistration"] = setting.Service.AllowOnlyInternalRegistration
-	ctx.Data["EnableCaptcha"] = setting.Service.EnableCaptcha
-	ctx.Data["Captcha"] = context.GetImageCaptcha()
-	ctx.Data["CaptchaType"] = setting.Service.CaptchaType
-	ctx.Data["RecaptchaSitekey"] = setting.Service.RecaptchaSitekey
-	ctx.Data["HcaptchaSitekey"] = setting.Service.HcaptchaSitekey
-	ctx.Data["RecaptchaURL"] = setting.Service.RecaptchaURL
-	ctx.Data["McaptchaSitekey"] = setting.Service.McaptchaSitekey
-	ctx.Data["McaptchaURL"] = setting.Service.McaptchaURL
-	ctx.Data["CfTurnstileSitekey"] = setting.Service.CfTurnstileSitekey
 	ctx.Data["OpenID"] = oid
+	prepareCommonAuthPageData(ctx, CommonAuthOptions{
+		EnableCaptcha: setting.Service.EnableCaptcha,
+	})
+	return oid
+}
+
+// RegisterOpenID shows a form to create a new user authenticated via an OpenID URI
+func RegisterOpenID(ctx *context.Context) {
+	oid := prepareRegisterOpenIDPageData(ctx)
+	if oid == "" {
+		return
+	}
+
 	userName, _ := ctx.Session.Get("openid_determined_username").(string)
 	if userName != "" {
 		ctx.Data["user_name"] = userName
@@ -322,19 +324,12 @@ func RegisterOpenID(ctx *context.Context) {
 
 // RegisterOpenIDPost handles submission of a form to create a new user authenticated via an OpenID URI
 func RegisterOpenIDPost(ctx *context.Context) {
-	form := web.GetForm(ctx).(*forms.SignUpOpenIDForm)
-	oid, _ := ctx.Session.Get("openid_verified_uri").(string)
+	oid := prepareRegisterOpenIDPageData(ctx)
 	if oid == "" {
-		ctx.Redirect(setting.AppSubURL + "/user/login/openid")
 		return
 	}
 
-	ctx.Data["Title"] = "OpenID signup"
-	ctx.Data["PageIsSignIn"] = true
-	ctx.Data["PageIsOpenIDRegister"] = true
-	ctx.Data["EnableOpenIDSignUp"] = setting.Service.EnableOpenIDSignUp
-	context.SetCaptchaData(ctx)
-	ctx.Data["OpenID"] = oid
+	form := web.GetForm(ctx).(*forms.SignUpOpenIDForm)
 
 	if setting.Service.AllowOnlyInternalRegistration {
 		ctx.HTTPError(http.StatusForbidden)