org.astrogrid.samp.web

Class UrlTracker

java.lang.Object

org.astrogrid.samp.web.UrlTracker

public class UrlTracker
extends Object

Keeps track of which URLs have been seen in communications inbound to and outbound from Web Profile clients. On the basis of these observations it is able to advise whether a Web Profile client ought to be permitted to dereference a given URL. The idea is that a Web Profile client, which may not be entirely trustworthy, has no legitimate reason for dereferencing an arbitrary URL, and should only be permitted to dereference local URLs if they have previously been sent as message arguments to it. (so for instance an attempt to read file:///etc/password is likely to be blocked). Since a SAMP client may be able to provoke some kind of echo, any URL which was mentioned by a Web Profile client before any other client mentions it is automatically marked as suspicious.

Details of the implementation are arguable.

Since:

22 Jul 2011

Author:

Mark Taylor

Constructor Summary

Constructors

Constructor and Description
UrlTracker() Constructor.

Method Summary

Modifier and Type	Method and Description
protected boolean	isSensitive(URL url) Indicates whether a given URL is potentially sensitive.
boolean	isUrlPermitted(URL url) Indicates whether access to a given URL should be permitted, according to the strategy implemented by this class, from a Web Profile client.
void	noteIncomingUrl(URL url) Note that a URL has been communicated to a Web Profile client from the outside world.
void	noteOutgoingUrl(URL url) Note that a Web Profile client has communicated a URL to the outside world.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

UrlTracker

public UrlTracker()

Constructor.

Method Detail

noteIncomingUrl

public void noteIncomingUrl(URL url)

Note that a URL has been communicated to a Web Profile client from the outside world.

Parameters:

url - incoming URL

noteOutgoingUrl

public void noteOutgoingUrl(URL url)

Note that a Web Profile client has communicated a URL to the outside world.

Parameters:

url - outgoing URL

isUrlPermitted

public boolean isUrlPermitted(URL url)

Indicates whether access to a given URL should be permitted, according to the strategy implemented by this class, from a Web Profile client.

Parameters:

url - URL to assess

Returns:

true iff permission to access is appropriate

isSensitive

protected boolean isSensitive(URL url)

Indicates whether a given URL is potentially sensitive. The current implementation always returns true. This is probably correct, since it's not in general possible to tell whether or not a given URL accords privileges to requests from the local host. But if this ends up letting too much through, identifying only file URLs and http/https ones on the local domain would probably be OK.

Parameters:

url - URL to assess

Returns:

true iff access should be restricted