camper/pkg/auth/user.go

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Add the logout button Conceptually, to logout we have to “delete the session”, thus the best HTTP verb would be `DELETE`. However, there is no way to send a `DELETE` request with a regular HTML form, and it seems that never will be[0]. I could use a POST, optionally with a “method override” technique, but i was planing to use HTMx anyway, so this was as good an opportunity to include it as any. In this application i am not concerned with people not having JavaScript enabled, because it is for a customer that has a known environment, and we do not have much time anyway. Therefore, i opted to forgo progressive enhancement in cases like this: if `DELETE` is needed, use `hx-delete`. Unfortunately, i can not use a <form> with a hidden <input> for the CSRF token, because `DELETE` requests do not have body and the value should be added as query parameters, like a form with GET method, but HTMx does the incorrect thing here: sends the values in the request’s body. That’s why i have to use a custom header and the `hx-header` directive to include the CSRF token. Then, by default HTMx targets the triggered element for swap with the response from the server, but after a logout i want to redirect the user to the login form again. I could set the hx-target to button to replace the whole body, or tell the client to redirect to the new location. I actually do not know which one is “better”. Maybe the hx-target is best because then everything is handled by the client, but in the case of logout, since it is possible that i might want to load scripts only for logged-in users in the future, i opted for the full page reload. However, HTMx does not want to reload a page that return HTTP 401, hence i had to include the GET method to /login in order to return the login form with a response of HTTP 200, which also helps when reloading in the browser after a failed login attempt. I am not worried with the HTTP 401 when attempting to load a page as guest, because this request most probably comes from the browser, not HTMx, and it will show the login form as intended—even though it is not compliant, since it does not return the WWW-Authenticate header, but this is the best i can do given that no cookie-based authentication method has been accepted[1]. [0]: https://www.w3.org/Bugs/Public/show_bug.cgi?id=10671#c16 [1]: https://datatracker.ietf.org/doc/id/draft-broyer-http-cookie-auth-00.html
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/*
* SPDX-FileCopyrightText: 2023 jordi fita mas <jfita@peritasoft.com>
* SPDX-License-Identifier: AGPL-3.0-only
*/
package auth
import (
"errors"
"net/http"
"golang.org/x/text/language"
"dev.tandem.ws/tandem/camper/pkg/locale"
)
const (
CSRFTokenField = "csrf_token"
CSRFTokenHeader = "X-CSRFToken"
)
type User struct {
ID int
Add the logout button Conceptually, to logout we have to “delete the session”, thus the best HTTP verb would be `DELETE`. However, there is no way to send a `DELETE` request with a regular HTML form, and it seems that never will be[0]. I could use a POST, optionally with a “method override” technique, but i was planing to use HTMx anyway, so this was as good an opportunity to include it as any. In this application i am not concerned with people not having JavaScript enabled, because it is for a customer that has a known environment, and we do not have much time anyway. Therefore, i opted to forgo progressive enhancement in cases like this: if `DELETE` is needed, use `hx-delete`. Unfortunately, i can not use a <form> with a hidden <input> for the CSRF token, because `DELETE` requests do not have body and the value should be added as query parameters, like a form with GET method, but HTMx does the incorrect thing here: sends the values in the request’s body. That’s why i have to use a custom header and the `hx-header` directive to include the CSRF token. Then, by default HTMx targets the triggered element for swap with the response from the server, but after a logout i want to redirect the user to the login form again. I could set the hx-target to button to replace the whole body, or tell the client to redirect to the new location. I actually do not know which one is “better”. Maybe the hx-target is best because then everything is handled by the client, but in the case of logout, since it is possible that i might want to load scripts only for logged-in users in the future, i opted for the full page reload. However, HTMx does not want to reload a page that return HTTP 401, hence i had to include the GET method to /login in order to return the login form with a response of HTTP 200, which also helps when reloading in the browser after a failed login attempt. I am not worried with the HTTP 401 when attempting to load a page as guest, because this request most probably comes from the browser, not HTMx, and it will show the login form as intended—even though it is not compliant, since it does not return the WWW-Authenticate header, but this is the best i can do given that no cookie-based authentication method has been accepted[1]. [0]: https://www.w3.org/Bugs/Public/show_bug.cgi?id=10671#c16 [1]: https://datatracker.ietf.org/doc/id/draft-broyer-http-cookie-auth-00.html
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Email string
LoggedIn bool
Role string
Language language.Tag
CSRFToken string
Locale *locale.Locale
}
func (user *User) VerifyCSRFToken(r *http.Request) error {
token := r.Header.Get(CSRFTokenHeader)
if token == "" {
token = r.FormValue(CSRFTokenField)
}
if user.CSRFToken == token {
return nil
}
return errors.New(user.Locale.Gettext("Cross-site request forgery detected."))
}
Split templates and handlers into admin and public I need to check that the user is an employee (or admin) in administration handlers, but i do not want to do it for each handler, because i am bound to forget it. Thus, i added the /admin sub-path for these resources. The public-facing web is the rest of the resources outside /admin, but for now there is only home, to test whether it works as expected or not. The public-facing web can not relay on the user’s language settings, as the guest user has no way to set that. I would be happy to just use the Accept-Language header for that, but apparently Google does not use that header[0], and they give four alternatives: a country-specific domain, a subdomain with a generic top-level domain (gTLD), subdirectories with a gTLD, or URL parameters (e.g., site.com?loc=de). Of the four, Google does not recommend URL parameters, and the customer is already using subdirectories with the current site, therefor that’s what i have chosen. Google also tells me that it is a very good idea to have links between localized version of the same resources, either with <link> elements, Link HTTP response headers, or a sitemap file[1]; they are all equivalent in the eyes of Google. I have choosen the Link response headers way, because for that i can simply “augment” ResponseHeader to automatically add these headers when the response status is 2xx, otherwise i would need to pass down the original URL path until it reaches the template. Even though Camper is supposed to be a “generic”, multi-company application, i think i will stick to the easiest route and write the templates for just the “first” customer. [0]: https://developers.google.com/search/docs/specialty/international/managing-multi-regional-sites [1]: https://developers.google.com/search/docs/specialty/international/localized-versions
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func (user *User) IsEmployee() bool {
role := user.Role[0]
return role == 'e' || role == 'a'
}
func (user *User) IsAdmin() bool {
return user.Role[0] == 'a'
}