cms/util/ACL.java

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

//---IMPORTS---
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 1.2 2002/02/15 22:27:15 tdb Exp $
 */
public class ACL implements Serializable {

//---FINAL ATTRIBUTES---

    /**
     * The current CVS revision of this class
     */
    public static final String REVISION = "$Revision: 1.2 $";
    
    /**
     * 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;
    }

    /**
     * Construct a new Access Control List with a given
     * String representation of the ACL rules. The String
     * should be of the format:
     *     expression:rule;expression:rule;expression:rule...
     * Where expression is a wildcard to match against, and
     * rule is either 'ALLOW' or 'DENY'. There is a special
     * expression of 'DEFAULT' which represents the default
     * rule (what should happen if no expression is matched
     * when performing a check).
     * The default mode is set to ALLOW if one is not
     * specified.
     *
     * @param acl a String representation of the ACL.
     */
    public ACL(String acl) {
        // default to ALLOW
        _defaultMode = ACL.ALLOW;
        if(acl != null) {
            // split the String into expression:rule parts
            StringTokenizer st1 = new StringTokenizer(acl, ";");
            while(st1.hasMoreTokens()) {
                String token1 = st1.nextToken();
                // if it doesn't have a :, it's not the correct format
                if(token1.indexOf(":") != -1) {
                    // split into expression and rule part
                    StringTokenizer st2 = new StringTokenizer(token1, ":");
                    String expression = "";
                    String rule = "";
                    if(st2.hasMoreTokens()) {
                        expression = st2.nextToken();
                    }
                    else {
                        // mall-formed?
                        continue;
                    }
                    if(st2.hasMoreTokens()) {
                        rule = st2.nextToken();
                    }
                    else {
                        // mall-formed?
                        continue;
                    }
                    // check to see what sort of rule
                    if(rule.equals("ALLOW")) {
                        // case for special 'DEFAULT' expression
                        if(expression.equals("DEFAULT")) {
                            _defaultMode = ACL.ALLOW;
                        }
                        else {
                            add(ACL.ALLOW, expression);
                        }
                    }
                    else if(rule.equals("DENY")) {
                        // case for special 'DEFAULT' expression
                        if(expression.equals("DEFAULT")) {
                            _defaultMode = ACL.DENY;
                        }
                        else {
                            add(ACL.DENY, expression);
                        }
                    }
                    // if it's not ALLOW or DENY, it's not a
                    // proper rule, so we'll ignore it
                }
            }
        }
    }

//---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
     * @return 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:	1.3
Committed:	Tue Mar 19 12:18:22 2002 UTC (22 years, 1 month ago) by tdb
Branch:	MAIN
Changes since 1.2:	+71 -2 lines
Log Message:	Added new constructor to take a String of the form: "expression:rule;expression:rule;expression:rule" This allows an ACL to be constructed from a single String, which is nice in the context of i-scream because we can read that from the config :)
#	Content
1	//---PACKAGE DECLARATION---
2	package uk.org.iscream.cms.server.util;
3
4	//---IMPORTS---
5	import java.util.ArrayList;
6	import java.util.StringTokenizer;
7	import java.net.InetAddress;
8	import java.io.Serializable;
9
10	/**
11	* Access Control List for use primarily
12	* with the ACLServerSocket. It could, however
13	* have other uses as it has a fairly generic
14	* behaviour. Rules are added using the add
15	* method, and then checks can be made using
16	* the relevant check method.
17	*
18	* @author $Author: tdb $
19	* @version $Id: ACL.java,v 1.2 2002/02/15 22:27:15 tdb Exp $
20	*/
21	public class ACL implements Serializable {
22
23	//---FINAL ATTRIBUTES---
24
25	/**
26	* The current CVS revision of this class
27	*/
28	public static final String REVISION = "$Revision: 1.2 $";
29
30	/**
31	* static to be used when adding an ALLOW rule to the ACL.
32	*/
33	public static final boolean ALLOW = true;
34
35	/**
36	* static to be used when adding a DENY rule to the ACL.
37	*/
38	public static final boolean DENY = false;
39
40	//---STATIC METHODS---
41
42	//---CONSTRUCTORS---
43
44	/**
45	* Construct a new Access Control List. The default
46	* mode is to ALLOW anything that isn't explicitly
47	* blocked by a rule.
48	*/
49	public ACL() {
50	// default to ACL.ALLOW
51	this(ACL.ALLOW);
52	}
53
54	/**
55	* Construct a new Access Control List with a given
56	* default mode. This mode specifies what should
57	* happen if a check does not match any rules.
58	*
59	* @param defaultMode the default mode for non-matched checks
60	*/
61	public ACL(boolean defaultMode) {
62	_defaultMode = defaultMode;
63	}
64
65	/**
66	* Construct a new Access Control List with a given
67	* String representation of the ACL rules. The String
68	* should be of the format:
69	* expression:rule;expression:rule;expression:rule...
70	* Where expression is a wildcard to match against, and
71	* rule is either 'ALLOW' or 'DENY'. There is a special
72	* expression of 'DEFAULT' which represents the default
73	* rule (what should happen if no expression is matched
74	* when performing a check).
75	* The default mode is set to ALLOW if one is not
76	* specified.
77	*
78	* @param acl a String representation of the ACL.
79	*/
80	public ACL(String acl) {
81	// default to ALLOW
82	_defaultMode = ACL.ALLOW;
83	if(acl != null) {
84	// split the String into expression:rule parts
85	StringTokenizer st1 = new StringTokenizer(acl, ";");
86	while(st1.hasMoreTokens()) {
87	String token1 = st1.nextToken();
88	// if it doesn't have a :, it's not the correct format
89	if(token1.indexOf(":") != -1) {
90	// split into expression and rule part
91	StringTokenizer st2 = new StringTokenizer(token1, ":");
92	String expression = "";
93	String rule = "";
94	if(st2.hasMoreTokens()) {
95	expression = st2.nextToken();
96	}
97	else {
98	// mall-formed?
99	continue;
100	}
101	if(st2.hasMoreTokens()) {
102	rule = st2.nextToken();
103	}
104	else {
105	// mall-formed?
106	continue;
107	}
108	// check to see what sort of rule
109	if(rule.equals("ALLOW")) {
110	// case for special 'DEFAULT' expression
111	if(expression.equals("DEFAULT")) {
112	_defaultMode = ACL.ALLOW;
113	}
114	else {
115	add(ACL.ALLOW, expression);
116	}
117	}
118	else if(rule.equals("DENY")) {
119	// case for special 'DEFAULT' expression
120	if(expression.equals("DEFAULT")) {
121	_defaultMode = ACL.DENY;
122	}
123	else {
124	add(ACL.DENY, expression);
125	}
126	}
127	// if it's not ALLOW or DENY, it's not a
128	// proper rule, so we'll ignore it
129	}
130	}
131	}
132	}
133
134	//---PUBLIC METHODS---
135
136	/**
137	* Add a new rule to the ACL immediately after the
138	* previous rule. The rule can either be an ACL.ALLOW
139	* rule, or an ACL.DENY rule. The expression can
140	* contain a wildcard (a * only). Rules can only be
141	* added to the end of the list.
142	*
143	* param allow whether this is an ALLOW or DENY rule
144	* param expression what this rule matches using wildcards
145	*/
146	public void add(boolean allow, String expression) {
147	// try and convert the expression into an IP address
148	short[] ipaddr = ipStringToShort(expression);
149	// a result of null means it's not an IP address
150	// add either a name rule or an IP rule
151	if(ipaddr != null) {
152	_acl.add(new ACLRule(allow, expression, ipaddr, true));
153	}
154	else {
155	_acl.add(new ACLRule(allow, expression, ipaddr, false));
156	}
157	}
158
159	/**
160	* Check to see if a string is permitted by the
161	* ACL. Useful for testing, and non-Socket uses
162	* of this class.
163	*
164	* @param address the string to check
165	* @return whether the address was permitted by the ACL
166	*/
167	public boolean check(String address) {
168	for(int i=0; i < _acl.size(); i++) {
169	ACLRule rule = (ACLRule) _acl.get(i);
170	if(StringUtils.wildcardMatch(address, rule._expression)) {
171	return rule._allow;
172	}
173	}
174	return _defaultMode;
175	}
176
177	/**
178	* Check to see if an InetAddress is permitted
179	* by the ACL. Perfect for Socket uses of this
180	* class. A rule will either be for a name, or
181	* an IP address (this is determined in the add
182	* method), and the appropriate comparison will
183	* be performed.
184	*
185	* @param address the InetAddress to check
186	* @return whether the InetAddress was permitted by the ACL
187	*/
188	public boolean check(InetAddress address) {
189	// gather the details first
190	String hostname = address.getHostName();
191	String ip = address.getHostAddress();
192	short[] ipaddr = ipStringToShort(ip);
193	// check each rule against this InetAddress
194	for(int i=0; i < _acl.size(); i++) {
195	ACLRule rule = (ACLRule) _acl.get(i);
196	if(rule._iprule) {
197	// if this is an IP rule do a short comparison
198	// must specify the wildcarded rule first
199	if(compareShorts(rule._ipaddr, ipaddr)) {
200	return rule._allow;
201	}
202	}
203	else {
204	// if not do a full blown String comparsion
205	if(StringUtils.wildcardMatch(hostname, rule._expression)) {
206	return rule._allow;
207	}
208	}
209
210	}
211	// if we haven't matched a rule, return the default
212	return _defaultMode;
213	}
214
215	/**
216	* Gives a String representation of this ACL.
217	*
218	* @return A String representation of this ACL.
219	*/
220	public String toString() {
221	StringBuffer acl = new StringBuffer();
222	// put in the i-scream toString code
223	acl.append(FormatName.getName(_name, getClass().getName(), REVISION));
224	acl.append("{");
225	// put the value of each Rule in the result
226	for(int i=0; i < _acl.size(); i++) {
227	acl.append((ACLRule) _acl.get(i));
228	acl.append(",");
229	}
230	// put the default mode in the result
231	if(_defaultMode) {
232	acl.append("DEFAULT=ALLOW");
233	}
234	else {
235	acl.append("DEFAULT=DENY");
236	}
237	acl.append("}");
238	return acl.toString();
239	}
240
241	//---PRIVATE METHODS---
242
243	/**
244	* Converts an IP address in String format into
245	* a short array of length 4. Any wildcards, *,
246	* found in the IP address are represented by
247	* a -1. If the given String is not an IP address
248	* null is returned instead.
249	*
250	* @param ip The IP address in String format
251	* @return The IP address in a short[]
252	*/
253	private short[] ipStringToShort(String ip) {
254	// default to expecting it to be an IP
255	// we will try to disprove this :)
256	short[] ipaddr = {-1, -1, -1, -1};
257	int i = 0;
258	String s = "";
259	// tokenize the String on fullstops, so we can break
260	// up the quads of an IP (if it's an IP!)
261	StringTokenizer st = new StringTokenizer(ip, ".");
262	while(st.hasMoreTokens() && i++ < 4) {
263	s = st.nextToken();
264	// if it's a wildcard, we'll skip to the next one
265	// as no more checks are required
266	if(s.equals("*")) {
267	continue;
268	}
269	// attempt to parse it into a short
270	try {
271	short n = Short.parseShort(s);
272	// if it's an int but outside of the
273	// valid range, it can't be an IP
274	if(n < 0 \|\| n > 255) {
275	// give up checking further
276	return null;
277	}
278	ipaddr[i-1] = n;
279	}
280	// if it didn't parse as a short it can't be an IP
281	catch (NumberFormatException e) {
282	// give up checking further
283	return null;
284	}
285	}
286	// we've done 4 parts, so if there's any
287	// more this can't be an IP
288	if(st.hasMoreTokens()) {
289	return null;
290	}
291	// if we've done less than 4, see if the last one
292	// was a wildcard - if it isn't then it's not an IP
293	// -- this allows 129.12.*
294	if(i < 4 && !s.equals("*")) {
295	return null;
296	}
297	// if we had one or less entries it can't be an IP
298	// -- this disallows * matching as an IP due
299	// to the rule above
300	if(i <= 1) {
301	return null;
302	}
303	return ipaddr;
304	}
305
306	/**
307	* Compares two short arrays. The first array can contain a -1,
308	* which will always match any value -- it's a wildcard.
309	* They must be the same length to match.
310	*
311	* @param first The first array to compare (with -1 wildcard if required)
312	* @param second The second array to compare
313	* @return the result of the comparison
314	*/
315	private boolean compareShorts(short[] first, short[] second) {
316	if(first.length != second.length) {
317	return false;
318	}
319	for(int i=0; i < first.length; i++) {
320	if(first[i] == -1) {
321	continue;
322	}
323	if(first[i] != second[i]) {
324	return false;
325	}
326	}
327	return true;
328	}
329
330	//---ACCESSOR/MUTATOR METHODS---
331
332	//---ATTRIBUTES---
333
334	/**
335	* This is the friendly identifier of the
336	* component this class is running in.
337	* eg, a Filter may be called "filter1",
338	* If this class does not have an owning
339	* component, a name from the configuration
340	* can be placed here. This name could also
341	* be changed to null for utility classes.
342	*/
343	private String _name = null;
344
345	/**
346	* The ACL is stored in this ArrayList.
347	*/
348	private ArrayList _acl = new ArrayList();
349
350	/**
351	* The default mode of this ACL.
352	*/
353	private boolean _defaultMode;
354
355	//---STATIC ATTRIBUTES---
356
357	//---INNER CLASSES---
358
359	/**
360	* Wrapper class for an ACL rule.
361	*/
362	private class ACLRule implements Serializable {
363
364	/**
365	* Construct an ACL rule.
366	*
367	* @param allow whether this is an ALLOW or DENY rule
368	* @param expression what this rule matches
369	* @param ipaddr the IP address wildcard this rule matches if it's an IP rule
370	* @param iprule whether this is an IP rule
371	*/
372	private ACLRule(boolean allow, String expression, short[] ipaddr, boolean iprule) {
373	_allow = allow;
374	_expression = expression;
375	_ipaddr = ipaddr;
376	_iprule = iprule;
377	}
378
379	/**
380	* Returns a String representation of this rule.
381	*
382	* @return A String representation of this rule.
383	*/
384	public String toString() {
385	if(_allow) {
386	return _expression + "=ALLOW";
387	}
388	else {
389	return _expression + "=DENY";
390	}
391	}
392
393	/**
394	* Whether this is an ALLOW or DENY rule.
395	*/
396	private boolean _allow;
397
398	/**
399	* What this rule matches.
400	*/
401	private String _expression;
402
403	/**
404	* The IP wildcard, only valid if this
405	* is an IP rule.
406	*/
407	private short[] _ipaddr;
408
409	/**
410	* Whether this is an IP rule.
411	*/
412	private boolean _iprule;
413
414	}
415
416	}