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With {{Version|9.0}} of BaseX, a light-weight permission layer has been added: * Functions Permission strings can be annotated with permission strings, andattached to RESTXQ functions.* Global permission With security functions , you can ensure that access to RESTXQ functions will only be written granted to ensure that the current user has clients with sufficient permissions.
It is completely up to the user which The permission strings are used in an application. The strings may denote ids, users, user groups, applications, or any other realms. It is completely up to the user which strings are used, and which functions will be annotated. In the given example code, only the last function has a {{Code|%perm:allow}} annotation.
NotesSome notes:
{| class="wikitable" widthAuthentication="100%"|- valign="top"! Key! Description|-| {{Code|allow}}| Permission strings attached to the requested function.|-| {{Code|path}}| Original path of the client request.|-| {{Code|method}}| Method of the client request ({{Code|GET}}, {{Code|POST}}, …)|}
The permission layer was designed to provide as much flexibility as possible to the web application developer. Some extreme cases: * It is possible to completely work without permission strings, and realize all access checks based on the request information (path, method, and properties returned by the [[Request Module]]).* Each RESTXQ function can be accompanied by its individual security function. The bare minimum is a single {{Code|%perm:check}} function. Without this function, existing {{Code|%perm:allow}} annotations will be ignored. ==Authentication== There are numerous ways how users can be authenticated in a web application(via OAuth, LDAP, …). The approach demonstrated on this page is pretty basic and straightforward:
This is demonstrated by The following lines of code complete the following example: <pre class="brush:xquery">declare %rest:path("/") %output:method("html")function localimage:login() { <html> <form action="login-check" method="post"> <input name="name"/> <input type="password" name="pass"/> <input type="submit"/> </form> </html>};
no edit summary
This page presents the web application permission layer of BaseX, which can be used along with [[RESTXQ]].
Non-trivial web applications require a user management: Users need to log in too to a web site in order to get access to protected parts of a web site, and depending pages; Depending on their status (role, user group, …), they can be offered different views; etc. One popular way to realize this is to start each RESTXQ function body with a call to a security function. This function raises an exception if The light-weight permission layer simplifies permission checks a user is not logged in, or has not enough permissions to call the requested REST endpoint.lot:
=Preliminaries=
With the {{Code|%perm:allow}} annotation, one or more permission strings can be attached to a RESTXQ function:
<pre classsyntaxhighlight lang="brush:xquery">(:~ Public login Login page(visible to everyone). :)declare %rest:path("/") %output:method("html")function local:adminlogin() { <html> Please log in...: <form action="/login-check" method="post"> <input name="name"/> <input type="password" name="pass"/> <input type="submit"/> </form> </html>
};
(:~ Restricted Main page(restricted to logged in users). :)declare %rest:path("/main") %output:method("html")function local:adminmain() { <html> Welcome to the main page!: <a href='/main/admin'>admin area</a>, <a href='/logout'>log out</a>. </html>
};
(:~ Admin page. :)
declare %rest:path("/main/admin") %output:method("html") %perm:allow("admin") function local:admin() { <html> Welcome to the privileged administrator admin page. </html>
};
</presyntaxhighlight>
==Checking permissionsPermissions==
Functions that are marked with {{Code|%perm:check}} are so-called ''Security Functions''. These functions will be invoked before the actual target actually requested function will be evaluated. Two arguments can be specified with the annotation:
* A path argument can be specified with the as first argument. Such a :** The security function will only be called if the path of the client request path starts with the given stringspecified path. ** In contrast to RESTXQ, all subordinate paths are included herewill be accepted as well.* With * If no path argument is specified, {{Code|/}} is assigned instead.* A variable can be specified in the second argument, various permission-specific information can . A map with the following keys will be bound to a mapthat variable:** {{Code|allow}}: Permission strings attached to the requested function; may be empty.** {{Code|path}}: Original path of the client request.** {{Code|method}}: Method of the client request ({{Code|GET}}, {{Code|POST}}, …).** {{Code|authorization}}: Value of the HTTP Authorization header string; may be empty.
An example:
<pre classsyntaxhighlight lang="brush:xquery">
import module namespace Session = 'http://basex.org/modules/session';
return web:redirect('/main')
};
</presyntaxhighlight>
* If several permission functions are available that match the user request, all of them will be called one by oneafter another. The function with the shorted shortest path argument will be called first. Accordingly, in the example, if the {{Code|/main/admin}} URL is requested, all three security functions will be runin the given order.* If a security function raises an error or returns any result XQuery value (which can be e.g. a [[Web Module#web:redirect|redirection or any other XQuery value]] to another web page), no other functions will be invoked. This means that the actually invoked function that has been requested by the client will only be evaluated if all security functions yield no result or and no error.* As shown in the first function, the {{Code|%perm:check}} annotation can be combined with other RESTXQ annotations (, excluding {{Code|%rest:path}} and {{Code|%rest:error}}.* In the example, it is assumed that a logged in user is bound to a session variable (see further below).
The mappermission layer was designed to provide as much flexibility as possible to the web application developer: It is possible to completely work without permission strings, and realize all access checks based on the request information (path, method, which can be bound and properties returned by the [[Request Module]]). It is also possible (but rather unhandy) to accompany each RESTXQ function by its individual security function. The bare minimum is a variable (in this example single {{Code|$%perm:check}})function. Without this function, has the following keysexisting {{Code|%perm:allow}} annotations will be ignored.
* A login HTML page allows you to enter your credentials (user name, password).
* A login check function verifies checks if the inputtyped in data matches one of the database users. If the input is valid, a session id will be set, and the user will be redirected to the main page. Otherwise, (s)he will be redirected the redirection points back to the login page.
* A logout page deletes the session id.
<syntaxhighlight lang="xquery">
declare
%rest:path("/login-check")
%rest:path("/logout")
function local:logout() {
Session:delete($cons:SESSION-KEY'id'),
web:redirect("/")
};
</presyntaxhighlight>
For a full round trip, check out the source code of the [[DBA]] that is bundled with BaseX.
=Changelog=
;Version 9.1
* Added: {{Code|authorization}} value in permissions map variable
The Module was introduced with Version 9.0.
