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 1.8 2001/12/31 02:57:00 tdb Exp $
 */
public class ACL implements Serializable {

//---FINAL ATTRIBUTES---

    /**
     * The current CVS revision of this class
     */
    public static final String REVISION = "$Revision: 1.8 $";
    
    /**
     * 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) {
        // default to expecting it to be an IP
        // we will try to disprove this :)
        boolean ip = true;
        short[] ipaddr = {-1, -1, -1, -1};
        int i = 0;
        String s = "";
        // tokenize the expression on fullstops, so we can break
        // up the quads of an IP (if it's an IP!)
        StringTokenizer st = new StringTokenizer(expression, ".");
        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) {
                    ip = false;
                    // give up checking further
                    break;
                }
                ipaddr[i-1] = n;
            }
            // if it didn't parse as an int it can't be an IP
            catch (NumberFormatException e) {
                ip = false;
                // give up checking further
                break;
            }
        }
        // we've done 4 parts, so if there's any
        // more this can't be an IP
        if(st.hasMoreTokens()) {
            ip = false;
        }
        // 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("*")) {
            ip = false;
        }
        // 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) {
            ip = false;
        }
        // add the rule to our array
        _acl.add(new ACLRule(allow, expression, ipaddr, ip));
    }
    
    /**
     * 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.wildcardCheck(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
                if(compareShorts(ipaddr, rule._ipaddr)) {
                    return rule._allow;
                }
            }
            else {
                // if not do a full blown String comparsion
                if(StringUtils.wildcardCheck(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.
     * 
     * @param ip The IP address in String format
     * @return The IP address in a short[]
     */
    private short[] ipStringToShort(String ip) {
        short[] ipaddr = {-1, -1, -1, -1};
        StringTokenizer st = new StringTokenizer(ip, ".");
        for(int i=0; i < 4 && st.hasMoreTokens(); i++) {
            try {
                ipaddr[i] = Short.parseShort(st.nextToken());
            }
            catch(NumberFormatException e) {
                // do nothing?
                // we just want to leave it as -1
                // -- actually, maybe we want to do more checks in here?
                //    although in this code context it'll probably be ok,
                //    it might be worth verifying wildcards and that the
                //    number is in range...
            }
        }
        return ipaddr;
    }
    
    /**
     * Compares two short arrays. The array can contain a -1, which
     * will always match any value -- it's a wildcard. They must be
     * the same length to match. At the moment the order of the
     * parameters does not matter.
     *
     * @param first The first array to compare
     * @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++) {
            // -- might want to consider specify which is the wildcard one?
            if(first[i] == -1 || second[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:	1.9
Committed:	Mon Dec 31 19:19:03 2001 UTC (22 years, 4 months ago) by tdb
Branch:	MAIN
Changes since 1.8:	+44 -22 lines
Log Message:	Some tidying up. Removed debugging code. Added required comments.
#	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 1.8 2001/12/31 02:57:00 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: 1.8 $";
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	// default to expecting it to be an IP
80	// we will try to disprove this :)
81	boolean ip = true;
82	short[] ipaddr = {-1, -1, -1, -1};
83	int i = 0;
84	String s = "";
85	// tokenize the expression on fullstops, so we can break
86	// up the quads of an IP (if it's an IP!)
87	StringTokenizer st = new StringTokenizer(expression, ".");
88	while(st.hasMoreTokens() && i++ < 4) {
89	s = st.nextToken();
90	// if it's a wildcard, we'll skip to the next one
91	// as no more checks are required
92	if(s.equals("*")) {
93	continue;
94	}
95	// attempt to parse it into a short
96	try {
97	short n = Short.parseShort(s);
98	// if it's an int but outside of the
99	// valid range, it can't be an IP
100	if(n < 0 \|\| n > 255) {
101	ip = false;
102	// give up checking further
103	break;
104	}
105	ipaddr[i-1] = n;
106	}
107	// if it didn't parse as an int it can't be an IP
108	catch (NumberFormatException e) {
109	ip = false;
110	// give up checking further
111	break;
112	}
113	}
114	// we've done 4 parts, so if there's any
115	// more this can't be an IP
116	if(st.hasMoreTokens()) {
117	ip = false;
118	}
119	// if we've done less than 4, see if the last one
120	// was a wildcard - if it isn't then it's not an IP
121	// -- this allows 129.12.*
122	if(i < 4 && !s.equals("*")) {
123	ip = false;
124	}
125	// if we had one or less entries it can't be an IP
126	// -- this disallows * matching as an IP due
127	// to the rule above
128	if(i <= 1) {
129	ip = false;
130	}
131	// add the rule to our array
132	_acl.add(new ACLRule(allow, expression, ipaddr, ip));
133	}
134
135	/**
136	* Check to see if a string is permitted by the
137	* ACL. Useful for testing, and non-Socket uses
138	* of this class.
139	*
140	* @param address the string to check
141	* @return whether the address was permitted by the ACL
142	*/
143	public boolean check(String address) {
144	for(int i=0; i < _acl.size(); i++) {
145	ACLRule rule = (ACLRule) _acl.get(i);
146	if(StringUtils.wildcardCheck(address, rule._expression)) {
147	return rule._allow;
148	}
149	}
150	return _defaultMode;
151	}
152
153	/**
154	* Check to see if an InetAddress is permitted
155	* by the ACL. Perfect for Socket uses of this
156	* class. A rule will either be for a name, or
157	* an IP address (this is determined in the add
158	* method), and the appropriate comparison will
159	* be performed.
160	*
161	* @param address the InetAddress to check
162	* @return whether the InetAddress was permitted by the ACL
163	*/
164	public boolean check(InetAddress address) {
165	// gather the details first
166	String hostname = address.getHostName();
167	String ip = address.getHostAddress();
168	short[] ipaddr = ipStringToShort(ip);
169	// check each rule against this InetAddress
170	for(int i=0; i < _acl.size(); i++) {
171	ACLRule rule = (ACLRule) _acl.get(i);
172	if(rule._iprule) {
173	// if this is an IP rule do a short comparison
174	if(compareShorts(ipaddr, rule._ipaddr)) {
175	return rule._allow;
176	}
177	}
178	else {
179	// if not do a full blown String comparsion
180	if(StringUtils.wildcardCheck(hostname, rule._expression)) {
181	return rule._allow;
182	}
183	}
184
185	}
186	// if we haven't matched a rule, return the default
187	return _defaultMode;
188	}
189
190	/**
191	* Gives a String representation of this ACL.
192	*
193	* @return A String representation of this ACL.
194	*/
195	public String toString() {
196	StringBuffer acl = new StringBuffer();
197	// put in the i-scream toString code
198	acl.append(FormatName.getName(_name, getClass().getName(), REVISION));
199	acl.append("{");
200	// put the value of each Rule in the result
201	for(int i=0; i < _acl.size(); i++) {
202	acl.append((ACLRule) _acl.get(i));
203	acl.append(",");
204	}
205	// put the default mode in the result
206	if(_defaultMode) {
207	acl.append("DEFAULT=ALLOW");
208	}
209	else {
210	acl.append("DEFAULT=DENY");
211	}
212	acl.append("}");
213	return acl.toString();
214	}
215
216	//---PRIVATE METHODS---
217
218	/**
219	* Converts an IP address in String format into
220	* a short array of length 4. Any wildcards, *,
221	* found in the IP address are represented by
222	* a -1.
223	*
224	* @param ip The IP address in String format
225	* @return The IP address in a short[]
226	*/
227	private short[] ipStringToShort(String ip) {
228	short[] ipaddr = {-1, -1, -1, -1};
229	StringTokenizer st = new StringTokenizer(ip, ".");
230	for(int i=0; i < 4 && st.hasMoreTokens(); i++) {
231	try {
232	ipaddr[i] = Short.parseShort(st.nextToken());
233	}
234	catch(NumberFormatException e) {
235	// do nothing?
236	// we just want to leave it as -1
237	// -- actually, maybe we want to do more checks in here?
238	// although in this code context it'll probably be ok,
239	// it might be worth verifying wildcards and that the
240	// number is in range...
241	}
242	}
243	return ipaddr;
244	}
245
246	/**
247	* Compares two short arrays. The array can contain a -1, which
248	* will always match any value -- it's a wildcard. They must be
249	* the same length to match. At the moment the order of the
250	* parameters does not matter.
251	*
252	* @param first The first array to compare
253	* @param second The second array to compare
254	* @result the result of the comparison
255	*/
256	private boolean compareShorts(short[] first, short[] second) {
257	if(first.length != second.length) {
258	return false;
259	}
260	for(int i=0; i < first.length; i++) {
261	// -- might want to consider specify which is the wildcard one?
262	if(first[i] == -1 \|\| second[i] == -1) {
263	continue;
264	}
265	if(first[i] != second[i]) {
266	return false;
267	}
268	return true;
269	}
270
271	//---ACCESSOR/MUTATOR METHODS---
272
273	//---ATTRIBUTES---
274
275	/**
276	* This is the friendly identifier of the
277	* component this class is running in.
278	* eg, a Filter may be called "filter1",
279	* If this class does not have an owning
280	* component, a name from the configuration
281	* can be placed here. This name could also
282	* be changed to null for utility classes.
283	*/
284	private String _name = null;
285
286	/**
287	* The ACL is stored in this ArrayList.
288	*/
289	private ArrayList _acl = new ArrayList();
290
291	/**
292	* The default mode of this ACL.
293	*/
294	private boolean _defaultMode;
295
296	//---STATIC ATTRIBUTES---
297
298	//---INNER CLASSES---
299
300	/**
301	* Wrapper class for an ACL rule.
302	*/
303	private class ACLRule implements Serializable {
304
305	/**
306	* Construct an ACL rule.
307	*
308	* @param allow whether this is an ALLOW or DENY rule
309	* @param expression what this rule matches
310	* @param ipaddr the IP address wildcard this rule matches if it's an IP rule
311	* @param iprule whether this is an IP rule
312	*/
313	private ACLRule(boolean allow, String expression, short[] ipaddr, boolean iprule) {
314	_allow = allow;
315	_expression = expression;
316	_ipaddr = ipaddr;
317	_iprule = iprule;
318	}
319
320	/**
321	* Returns a String representation of this rule.
322	*
323	* @return A String representation of this rule.
324	*/
325	public String toString() {
326	if(_allow) {
327	return _expression + "=ALLOW";
328	}
329	else {
330	return _expression + "=DENY";
331	}
332	}
333
334	/**
335	* Whether this is an ALLOW or DENY rule.
336	*/
337	private boolean _allow;
338
339	/**
340	* What this rule matches.
341	*/
342	private String _expression;
343
344	/**
345	* The IP wildcard, only valid if this
346	* is an IP rule.
347	*/
348	private short[] _ipaddr;
349
350	/**
351	* Whether this is an IP rule.
352	*/
353	private boolean _iprule;
354
355	}
356
357	}