| File |
Description |
|
The main JSP/Servlet configuration file |
|
The home page for the website |
|
The JSP page containing the login form |
|
A JSP page that causes a logout |
|
The home page for authenticated users. |
|
The more specific home page for Professor's, available only to users in role 'professor' |
|
The more specific home page for Student's, available to users in role 'student' or in role 'professor' |
|
The more specific home page for Staff, available to users in role 'staff' or in role 'professor' |
|
An include file to render a button bar |
|
An include file to render a footer |
|
An include file to stop the browser from caching pages |
Each user belongs to one or more roles. These roles are
similar to groups in Unix. The possible roles are specified
in web.xml.
In this example, a user is either a professor, a
student, or a staff. They can also optionally
have an additional role of gryffindor,
slytherin, hufflepuf, or ravenclaw,
indicating which house they belong to (or none at all).
You can limit areas of the website to users in a certain
role. You specify url patterns in web.xml and the role
that is required. In JSP/Servlet terminology, this is called Declarative Security.
<web-app xmlns="http://caucho.com/ns/resin"
xmlns:resin="urn:java:com.caucho.resin">
<resin:Allow url-pattern="/professors/*">
<resin:IfUserInRole role="professor"/>
</resin:Allow>
</web-app>
A login form can be used to retrieve the username and password
from the user. The same form or a seperate form can be used
when the login fails.
In this example the login form and the error form are in the
same JSP file. If the form is being redisplayed because of an
error the login_error request parameter is set to '1'.
<web-app xmlns="http://caucho.com/ns/resin"
xmlns:resin="urn:java:com.caucho.resin">
<resin:FormLogin>
<login-page>/login.jsp</login-page>
<error-page>/login.jsp?login_error=1</error-page>
</resin:FormLogin>
...
</web-app>
<form action='j_security_check' method='POST'>
<table>
<tr><td>User:</td><td><input type='text' name='j_username'></td></tr>
<tr><td>Password:</td><td><input type='password' name='j_password'></td></tr>
<tr><td colspan='2'><input type=submit></td></tr>
</table>
<!--
- In case the user got here without a session, redirect
- successful requests to the home page for authenticated
- users. (This is a non-standard, but useful field.)
-->
<input type='hidden' name='j_uri' value='/home.jsp'/>
</form>
Resin will cause a login to occur when a url that points to
a secure area is used. You do not make a url directly to the
jsp page that contains the login form.
In this example, home.jsp is in a secure area, so an
unauthenticated user trying to access it will first be
presented with the login form.
<web-app xmlns="http://caucho.com/ns/resin"
xmlns:resin="urn:java:com.caucho.resin">
<resin:Allow url-pattern="/home.jsp">
<!--
'*' for a <role-name> means "authenticated user with any role"
The user must be logged in with some kind of role to access
the home page.
-->
<resin:IfUserInRole role="*"/>
</resin:Allow>
</web-app>
<a href="<c:url value='/home.jsp'/>">login</a>
If the user has done a successfull login, we say that they
have been authenticated.
request.getUserPrincipal() returns null if the
user has not been authenticated.
In this example it is used to determine whether a 'login' or a
'logout' link should be presented.
<c:choose>
<c:when test="${empty pageContext.request.userPrincipal}">
<a href="<c:url value='home.jsp'/>">login</a>
</c:when>
<c:otherwise>
<a href="<c:url value='logout.jsp'/>">logout</a>
</c:otherwise>
</c:choose>
Welcome <c:out value="${pageContext.request.remoteUser}"/>.
You can also determine if a user is in a certain role in the
body of the page using request.isUserInRole("role").
In JSP/Servlet terminology, this is called
Programmatic Security.
In this example, the home.jsp redirects the user to a
more specific home page if the user is a professor,
student, or staff.
<%
/** redirect to a more specific homepage if one is available */
String home_url = null;
if (request.isUserInRole("professor")) {
home_url = "professors/";
} else if (request.isUserInRole("staff")) {
home_url = "staff/";
} else if (request.isUserInRole("student")) {
home_url = "students/";
}
if (home_url != null) {
home_url = response.encodeRedirectUrl(home_url);
response.sendRedirect(home_url);
return; // don't do any more of the page
}
%>
Pages with information that changes depending on whether or
not there is a known user should not be cached by the
browser.
In this example an include file inc/nobrowsercache.jspf
is used to send the HTTP headers that stop the browser from
caching the page. It is used for each page that shows the
button bar at the top, because the button bar changes
depending on whether or not the user is logged in.
<%-- stop the browser from caching the page --%>
<%
response.setHeader("Cache-Control","no-cache,post-check=0,pre-check=0");
response.setHeader("Pragma","no-cache");
response.setHeader("Expires","Thu,01Dec199416:00:00GMT");
%>
<%@ include file="/inc/nobrowsercache.jspf" %>
A user can be logged out by invalidating the session. This
causes all of the information stored in the session to be
lost. It is especially important to make sure that the
logout page is not cached by the browser.
<%@ include file="/inc/nobrowsercache.jspf" %>
<%-- invalidating the session causes a loss of all session
information, including the identity of the user
--%>
<% session.invalidate(); %>
Resin provides an authenticator
which is
useful for sites which have minimal security requirements.
The developer places entries for users in the authenticator
configuration, or in an xml file, or both.
The example below uses digest passwords. Digest passwords avoid the storage of passwords in cleartext, and are discussed under the security section of the Resin documentation.
<web-app xmlns="http://caucho.com/ns/resin"
resin:xmlns="urn:java:com.caucho.resin">
<!-- Resin-specific XmlAuthenticator configuration -->
<resin:XmlAuthenticator>
<!-- Optionally put user information here. -->
<user>pince:Txpd1jQc/xwhISIqodEjfw==:staff,website</user>
<user>filch:KmZIq2RKXAHV4BaoNHfupQ==:staff</user>
<!-- You can also use an external file -->
<path>WEB-INF/password.xml</path>
</resin:XmlAuthenticator>
</web-app>
<!-- password.xml -->
<authenticator>
<!-- professors -->
<user name='snape' password='I7HdZr7CTM6hZLlSd2o+CA==' roles='professor,slytherin'/>
<user name='mcgonagall' password='4slsTREVeTo0sv5hGkZWag==' roles='professor,gryffindor'/>
<!-- students -->
<user name='harry' password='uTOZTGaB6pooMDvqvl2Lbg==' roles='student,gryffindor'/>
<user name='dmalfoy' password='yI2uN1l97Rv5E6mdRnDFwQ==' roles='student,slytherin'/>
<!-- alumni -->
<user name='lmalfoy' password='sj/yhtU1h4LZPw7/Uy9IVA==' roles='alumni,gryffindor'/>
</authenticator>
<web-app xmlns="http://caucho.com/ns/resin">
<security-role>
<role-name>professor</role-name>
</security-role>
</web-app>