server/ACL/ACL.java

//---PACKAGE DECLARATION---
//package uk.org.iscream.cms.server.util;

//---IMPORTS---
import uk.org.iscream.cms.server.util.*;
import java.util.ArrayList;
import java.util.StringTokenizer;
import java.net.InetAddress;
import java.io.Serializable;

/**
 * Access Control List for use primarily
 * with the ACLServerSocket. It could, however
 * have other uses as it has a fairly generic
 * behaviour. Rules are added using the add
 * method, and then checks can be made using
 * the relevant check method.
 *
 * @author  $Author: tdb $
 * @version $Id: ACL.java,v 1.11 2002/01/06 23:32:27 tdb Exp $
 */
public class ACL implements Serializable {

//---FINAL ATTRIBUTES---

    /**
     * The current CVS revision of this class
     */
    public static final String REVISION = "$Revision: 1.11 $";
    
    /**
     * static to be used when adding an ALLOW rule to the ACL.
     */
    public static final boolean ALLOW = true;
    
    /**
     * static to be used when adding a DENY rule to the ACL.
     */
    public static final boolean DENY = false;

//---STATIC METHODS---

//---CONSTRUCTORS---

    /**
     * Construct a new Access Control List. The default
     * mode is to ALLOW anything that isn't explicitly
     * blocked by a rule.
     */
    public ACL() {
        // default to ACL.ALLOW
        this(ACL.ALLOW);
    }
    
    /**
     * Construct a new Access Control List with a given
     * default mode. This mode specifies what should
     * happen if a check does not match any rules.
     *
     * @param defaultMode the default mode for non-matched checks
     */
    public ACL(boolean defaultMode) {
        _defaultMode = defaultMode;
    }

//---PUBLIC METHODS---

    /**
     * Add a new rule to the ACL immediately after the
     * previous rule. The rule can either be an ACL.ALLOW
     * rule, or an ACL.DENY rule. The expression can
     * contain a wildcard (a * only). Rules can only be
     * added to the end of the list.
     *
     * param allow whether this is an ALLOW or DENY rule
     * param expression what this rule matches using wildcards
     */
    public void add(boolean allow, String expression) {
        // try and convert the expression into an IP address
        short[] ipaddr = ipStringToShort(expression);
        // a result of null means it's not an IP address
        // add either a name rule or an IP rule
        if(ipaddr != null) {
            _acl.add(new ACLRule(allow, expression, ipaddr, true));
        }
        else {
            _acl.add(new ACLRule(allow, expression, ipaddr, false));
        }
    }
    
    /**
     * Check to see if a string is permitted by the
     * ACL. Useful for testing, and non-Socket uses
     * of this class.
     *
     * @param address the string to check
     * @return whether the address was permitted by the ACL
     */
    public boolean check(String address) {
        for(int i=0; i < _acl.size(); i++) {
            ACLRule rule = (ACLRule) _acl.get(i);
            if(StringUtils.wildcardMatch(address, rule._expression)) {
                return rule._allow;
            }
        }
        return _defaultMode;
    }
    
    /**
     * Check to see if an InetAddress is permitted
     * by the ACL. Perfect for Socket uses of this
     * class. A rule will either be for a name, or
     * an IP address (this is determined in the add
     * method), and the appropriate comparison will
     * be performed.
     *
     * @param address the InetAddress to check
     * @return whether the InetAddress was permitted by the ACL
     */
    public boolean check(InetAddress address) {
        // gather the details first
        String hostname = address.getHostName();
        String ip = address.getHostAddress();
        short[] ipaddr = ipStringToShort(ip);
        // check each rule against this InetAddress
        for(int i=0; i < _acl.size(); i++) {
            ACLRule rule = (ACLRule) _acl.get(i);
            if(rule._iprule) {
                // if this is an IP rule do a short comparison
                // must specify the wildcarded rule first
                if(compareShorts(rule._ipaddr, ipaddr)) {
                    return rule._allow;
                }
            }
            else {
                // if not do a full blown String comparsion
                if(StringUtils.wildcardMatch(hostname, rule._expression)) {
                    return rule._allow;
                }
            }
            
        }
        // if we haven't matched a rule, return the default
        return _defaultMode;
    }
    
    /**
     * Gives a String representation of this ACL.
     *
     * @return A String representation of this ACL.
     */
    public String toString() {
        StringBuffer acl = new StringBuffer();
        // put in the i-scream toString code
        acl.append(FormatName.getName(_name, getClass().getName(), REVISION));
        acl.append("{");
        // put the value of each Rule in the result
        for(int i=0; i < _acl.size(); i++) {
            acl.append((ACLRule) _acl.get(i));
            acl.append(",");
        }
        // put the default mode in the result
        if(_defaultMode) {
            acl.append("DEFAULT=ALLOW");
        }
        else {
            acl.append("DEFAULT=DENY");
        }
        acl.append("}");
        return acl.toString();
    }

//---PRIVATE METHODS---

    /**
     * Converts an IP address in String format into
     * a short array of length 4. Any wildcards, *,
     * found in the IP address are represented by
     * a -1. If the given String is not an IP address
     * null is returned instead.
     * 
     * @param ip The IP address in String format
     * @return The IP address in a short[]
     */
    private short[] ipStringToShort(String ip) {
        // default to expecting it to be an IP
        // we will try to disprove this :)
        short[] ipaddr = {-1, -1, -1, -1};
        int i = 0;
        String s = "";
        // tokenize the String on fullstops, so we can break
        // up the quads of an IP (if it's an IP!)
        StringTokenizer st = new StringTokenizer(ip, ".");
        while(st.hasMoreTokens() && i++ < 4) {
            s = st.nextToken();
            // if it's a wildcard, we'll skip to the next one
            // as no more checks are required
            if(s.equals("*")) {
                continue;
            }
            // attempt to parse it into a short
            try {
                short n = Short.parseShort(s);
                // if it's an int but outside of the
                // valid range, it can't be an IP
                if(n < 0 || n > 255) {
                    // give up checking further
                    return null;
                }
                ipaddr[i-1] = n;
            }
            // if it didn't parse as a short it can't be an IP
            catch (NumberFormatException e) {
                // give up checking further
                return null;
            }
        }
        // we've done 4 parts, so if there's any
        // more this can't be an IP
        if(st.hasMoreTokens()) {
            return null;
        }
        // if we've done less than 4, see if the last one
        // was a wildcard - if it isn't then it's not an IP
        //   -- this allows 129.12.*
        if(i < 4 && !s.equals("*")) {
            return null;
        }
        // if we had one or less entries it can't be an IP
        //   -- this disallows * matching as an IP due
        //      to the rule above
        if(i <= 1) {
            return null;
        }
        return ipaddr;
    }
    
    /**
     * Compares two short arrays. The first array can contain a -1,
     * which will always match any value -- it's a wildcard.
     * They must be the same length to match.
     *
     * @param first The first array to compare (with -1 wildcard if required)
     * @param second The second array to compare
     * @result the result of the comparison
     */
    private boolean compareShorts(short[] first, short[] second) {
        if(first.length != second.length) {
            return false;
        }
        for(int i=0; i < first.length; i++) {
            if(first[i] == -1) {
                continue;
            }
            if(first[i] != second[i]) {
                return false;
            }
        }
        return true;
    }

//---ACCESSOR/MUTATOR METHODS---

//---ATTRIBUTES---

    /**
     * This is the friendly identifier of the
     * component this class is running in.
     * eg, a Filter may be called "filter1",
     * If this class does not have an owning
     * component,  a name from the configuration
     * can be placed here.  This name could also
     * be changed to null for utility classes.
     */
    private String _name = null;
    
    /**
     * The ACL is stored in this ArrayList.
     */
    private ArrayList _acl = new ArrayList();
    
    /**
     * The default mode of this ACL.
     */
    private boolean _defaultMode;

//---STATIC ATTRIBUTES---

//---INNER CLASSES---

    /**
     * Wrapper class for an ACL rule.
     */
    private class ACLRule implements Serializable {
        
        /**
         * Construct an ACL rule.
         *
         * @param allow whether this is an ALLOW or DENY rule
         * @param expression what this rule matches
         * @param ipaddr the IP address wildcard this rule matches if it's an IP rule
         * @param iprule whether this is an IP rule
         */
        private ACLRule(boolean allow, String expression, short[] ipaddr, boolean iprule) {
            _allow = allow;
            _expression = expression;
            _ipaddr = ipaddr;
            _iprule = iprule;
        }
        
        /**
         * Returns a String representation of this rule.
         *
         * @return A String representation of this rule.
         */
        public String toString() {
            if(_allow) {
                return _expression + "=ALLOW";
            }
            else {
                return _expression + "=DENY";
            }
        }
        
        /**
         * Whether this is an ALLOW or DENY rule.
         */
        private boolean _allow;
        
        /**
         * What this rule matches.
         */
        private String _expression;
        
        /**
         * The IP wildcard, only valid if this
         * is an IP rule.
         */
        private short[] _ipaddr;
        
        /**
         * Whether this is an IP rule.
         */
        private boolean _iprule;
        
    }

}
Revision:	1.12
Committed:	Tue Jan 8 13:31:34 2002 UTC (22 years, 10 months ago) by tdb
Branch:	MAIN
CVS Tags:	HEAD
Changes since 1.11:	+57 -66 lines
Log Message:	Some final tidying to the ACL code. The IP address checking has been moved out of the add method to a more suitable location. The code now seems to be more readable. This should be the last 'feature' that needs doing.
#	Content
1	//---PACKAGE DECLARATION---
2	//package uk.org.iscream.cms.server.util;
3
4	//---IMPORTS---
5	import uk.org.iscream.cms.server.util.*;
6	import java.util.ArrayList;
7	import java.util.StringTokenizer;
8	import java.net.InetAddress;
9	import java.io.Serializable;
10
11	/**
12	* Access Control List for use primarily
13	* with the ACLServerSocket. It could, however
14	* have other uses as it has a fairly generic
15	* behaviour. Rules are added using the add
16	* method, and then checks can be made using
17	* the relevant check method.
18	*
19	* @author $Author: tdb $
20	* @version $Id: ACL.java,v 1.11 2002/01/06 23:32:27 tdb Exp $
21	*/
22	public class ACL implements Serializable {
23
24	//---FINAL ATTRIBUTES---
25
26	/**
27	* The current CVS revision of this class
28	*/
29	public static final String REVISION = "$Revision: 1.11 $";
30
31	/**
32	* static to be used when adding an ALLOW rule to the ACL.
33	*/
34	public static final boolean ALLOW = true;
35
36	/**
37	* static to be used when adding a DENY rule to the ACL.
38	*/
39	public static final boolean DENY = false;
40
41	//---STATIC METHODS---
42
43	//---CONSTRUCTORS---
44
45	/**
46	* Construct a new Access Control List. The default
47	* mode is to ALLOW anything that isn't explicitly
48	* blocked by a rule.
49	*/
50	public ACL() {
51	// default to ACL.ALLOW
52	this(ACL.ALLOW);
53	}
54
55	/**
56	* Construct a new Access Control List with a given
57	* default mode. This mode specifies what should
58	* happen if a check does not match any rules.
59	*
60	* @param defaultMode the default mode for non-matched checks
61	*/
62	public ACL(boolean defaultMode) {
63	_defaultMode = defaultMode;
64	}
65
66	//---PUBLIC METHODS---
67
68	/**
69	* Add a new rule to the ACL immediately after the
70	* previous rule. The rule can either be an ACL.ALLOW
71	* rule, or an ACL.DENY rule. The expression can
72	* contain a wildcard (a * only). Rules can only be
73	* added to the end of the list.
74	*
75	* param allow whether this is an ALLOW or DENY rule
76	* param expression what this rule matches using wildcards
77	*/
78	public void add(boolean allow, String expression) {
79	// try and convert the expression into an IP address
80	short[] ipaddr = ipStringToShort(expression);
81	// a result of null means it's not an IP address
82	// add either a name rule or an IP rule
83	if(ipaddr != null) {
84	_acl.add(new ACLRule(allow, expression, ipaddr, true));
85	}
86	else {
87	_acl.add(new ACLRule(allow, expression, ipaddr, false));
88	}
89	}
90
91	/**
92	* Check to see if a string is permitted by the
93	* ACL. Useful for testing, and non-Socket uses
94	* of this class.
95	*
96	* @param address the string to check
97	* @return whether the address was permitted by the ACL
98	*/
99	public boolean check(String address) {
100	for(int i=0; i < _acl.size(); i++) {
101	ACLRule rule = (ACLRule) _acl.get(i);
102	if(StringUtils.wildcardMatch(address, rule._expression)) {
103	return rule._allow;
104	}
105	}
106	return _defaultMode;
107	}
108
109	/**
110	* Check to see if an InetAddress is permitted
111	* by the ACL. Perfect for Socket uses of this
112	* class. A rule will either be for a name, or
113	* an IP address (this is determined in the add
114	* method), and the appropriate comparison will
115	* be performed.
116	*
117	* @param address the InetAddress to check
118	* @return whether the InetAddress was permitted by the ACL
119	*/
120	public boolean check(InetAddress address) {
121	// gather the details first
122	String hostname = address.getHostName();
123	String ip = address.getHostAddress();
124	short[] ipaddr = ipStringToShort(ip);
125	// check each rule against this InetAddress
126	for(int i=0; i < _acl.size(); i++) {
127	ACLRule rule = (ACLRule) _acl.get(i);
128	if(rule._iprule) {
129	// if this is an IP rule do a short comparison
130	// must specify the wildcarded rule first
131	if(compareShorts(rule._ipaddr, ipaddr)) {
132	return rule._allow;
133	}
134	}
135	else {
136	// if not do a full blown String comparsion
137	if(StringUtils.wildcardMatch(hostname, rule._expression)) {
138	return rule._allow;
139	}
140	}
141
142	}
143	// if we haven't matched a rule, return the default
144	return _defaultMode;
145	}
146
147	/**
148	* Gives a String representation of this ACL.
149	*
150	* @return A String representation of this ACL.
151	*/
152	public String toString() {
153	StringBuffer acl = new StringBuffer();
154	// put in the i-scream toString code
155	acl.append(FormatName.getName(_name, getClass().getName(), REVISION));
156	acl.append("{");
157	// put the value of each Rule in the result
158	for(int i=0; i < _acl.size(); i++) {
159	acl.append((ACLRule) _acl.get(i));
160	acl.append(",");
161	}
162	// put the default mode in the result
163	if(_defaultMode) {
164	acl.append("DEFAULT=ALLOW");
165	}
166	else {
167	acl.append("DEFAULT=DENY");
168	}
169	acl.append("}");
170	return acl.toString();
171	}
172
173	//---PRIVATE METHODS---
174
175	/**
176	* Converts an IP address in String format into
177	* a short array of length 4. Any wildcards, *,
178	* found in the IP address are represented by
179	* a -1. If the given String is not an IP address
180	* null is returned instead.
181	*
182	* @param ip The IP address in String format
183	* @return The IP address in a short[]
184	*/
185	private short[] ipStringToShort(String ip) {
186	// default to expecting it to be an IP
187	// we will try to disprove this :)
188	short[] ipaddr = {-1, -1, -1, -1};
189	int i = 0;
190	String s = "";
191	// tokenize the String on fullstops, so we can break
192	// up the quads of an IP (if it's an IP!)
193	StringTokenizer st = new StringTokenizer(ip, ".");
194	while(st.hasMoreTokens() && i++ < 4) {
195	s = st.nextToken();
196	// if it's a wildcard, we'll skip to the next one
197	// as no more checks are required
198	if(s.equals("*")) {
199	continue;
200	}
201	// attempt to parse it into a short
202	try {
203	short n = Short.parseShort(s);
204	// if it's an int but outside of the
205	// valid range, it can't be an IP
206	if(n < 0 \|\| n > 255) {
207	// give up checking further
208	return null;
209	}
210	ipaddr[i-1] = n;
211	}
212	// if it didn't parse as a short it can't be an IP
213	catch (NumberFormatException e) {
214	// give up checking further
215	return null;
216	}
217	}
218	// we've done 4 parts, so if there's any
219	// more this can't be an IP
220	if(st.hasMoreTokens()) {
221	return null;
222	}
223	// if we've done less than 4, see if the last one
224	// was a wildcard - if it isn't then it's not an IP
225	// -- this allows 129.12.*
226	if(i < 4 && !s.equals("*")) {
227	return null;
228	}
229	// if we had one or less entries it can't be an IP
230	// -- this disallows * matching as an IP due
231	// to the rule above
232	if(i <= 1) {
233	return null;
234	}
235	return ipaddr;
236	}
237
238	/**
239	* Compares two short arrays. The first array can contain a -1,
240	* which will always match any value -- it's a wildcard.
241	* They must be the same length to match.
242	*
243	* @param first The first array to compare (with -1 wildcard if required)
244	* @param second The second array to compare
245	* @result the result of the comparison
246	*/
247	private boolean compareShorts(short[] first, short[] second) {
248	if(first.length != second.length) {
249	return false;
250	}
251	for(int i=0; i < first.length; i++) {
252	if(first[i] == -1) {
253	continue;
254	}
255	if(first[i] != second[i]) {
256	return false;
257	}
258	}
259	return true;
260	}
261
262	//---ACCESSOR/MUTATOR METHODS---
263
264	//---ATTRIBUTES---
265
266	/**
267	* This is the friendly identifier of the
268	* component this class is running in.
269	* eg, a Filter may be called "filter1",
270	* If this class does not have an owning
271	* component, a name from the configuration
272	* can be placed here. This name could also
273	* be changed to null for utility classes.
274	*/
275	private String _name = null;
276
277	/**
278	* The ACL is stored in this ArrayList.
279	*/
280	private ArrayList _acl = new ArrayList();
281
282	/**
283	* The default mode of this ACL.
284	*/
285	private boolean _defaultMode;
286
287	//---STATIC ATTRIBUTES---
288
289	//---INNER CLASSES---
290
291	/**
292	* Wrapper class for an ACL rule.
293	*/
294	private class ACLRule implements Serializable {
295
296	/**
297	* Construct an ACL rule.
298	*
299	* @param allow whether this is an ALLOW or DENY rule
300	* @param expression what this rule matches
301	* @param ipaddr the IP address wildcard this rule matches if it's an IP rule
302	* @param iprule whether this is an IP rule
303	*/
304	private ACLRule(boolean allow, String expression, short[] ipaddr, boolean iprule) {
305	_allow = allow;
306	_expression = expression;
307	_ipaddr = ipaddr;
308	_iprule = iprule;
309	}
310
311	/**
312	* Returns a String representation of this rule.
313	*
314	* @return A String representation of this rule.
315	*/
316	public String toString() {
317	if(_allow) {
318	return _expression + "=ALLOW";
319	}
320	else {
321	return _expression + "=DENY";
322	}
323	}
324
325	/**
326	* Whether this is an ALLOW or DENY rule.
327	*/
328	private boolean _allow;
329
330	/**
331	* What this rule matches.
332	*/
333	private String _expression;
334
335	/**
336	* The IP wildcard, only valid if this
337	* is an IP rule.
338	*/
339	private short[] _ipaddr;
340
341	/**
342	* Whether this is an IP rule.
343	*/
344	private boolean _iprule;
345
346	}
347
348	}