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 1.10 2001/12/31 19:25:39 tdb Exp $
 */
public class ACL implements Serializable {

//---FINAL ATTRIBUTES---

    /**
     * The current CVS revision of this class
     */
    public static final String REVISION = "$Revision: 1.10 $";
    
    /**
     * 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
                // 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.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 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:	1.11
Committed:	Sun Jan 6 23:32:27 2002 UTC (22 years, 10 months ago) by tdb
Branch:	MAIN
Changes since 1.10:	+10 -11 lines
Log Message:	Minor tweak to the short[] comparing code. By ensuring the wildcarded array is the first one, we can perform less checks :-) As this is just in a local context, the tighter coupling to the rest of the code is probably ok. One more change to be made in the String to short[] method -- it needs to do some more rigourous tests, and possibly return an error if the String cannot be parsed into an IP address. At the moment it assumes the add method has already done this. This could also make the add method neater as it would not need to do as many checks, and would therefore look neater.
#	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 1.10 2001/12/31 19:25:39 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: 1.10 $";
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	// must specify the wildcarded rule first
175	if(compareShorts(rule._ipaddr, ipaddr)) {
176	return rule._allow;
177	}
178	}
179	else {
180	// if not do a full blown String comparsion
181	if(StringUtils.wildcardCheck(hostname, rule._expression)) {
182	return rule._allow;
183	}
184	}
185
186	}
187	// if we haven't matched a rule, return the default
188	return _defaultMode;
189	}
190
191	/**
192	* Gives a String representation of this ACL.
193	*
194	* @return A String representation of this ACL.
195	*/
196	public String toString() {
197	StringBuffer acl = new StringBuffer();
198	// put in the i-scream toString code
199	acl.append(FormatName.getName(_name, getClass().getName(), REVISION));
200	acl.append("{");
201	// put the value of each Rule in the result
202	for(int i=0; i < _acl.size(); i++) {
203	acl.append((ACLRule) _acl.get(i));
204	acl.append(",");
205	}
206	// put the default mode in the result
207	if(_defaultMode) {
208	acl.append("DEFAULT=ALLOW");
209	}
210	else {
211	acl.append("DEFAULT=DENY");
212	}
213	acl.append("}");
214	return acl.toString();
215	}
216
217	//---PRIVATE METHODS---
218
219	/**
220	* Converts an IP address in String format into
221	* a short array of length 4. Any wildcards, *,
222	* found in the IP address are represented by
223	* a -1.
224	*
225	* @param ip The IP address in String format
226	* @return The IP address in a short[]
227	*/
228	private short[] ipStringToShort(String ip) {
229	short[] ipaddr = {-1, -1, -1, -1};
230	StringTokenizer st = new StringTokenizer(ip, ".");
231	for(int i=0; i < 4 && st.hasMoreTokens(); i++) {
232	try {
233	ipaddr[i] = Short.parseShort(st.nextToken());
234	}
235	catch(NumberFormatException e) {
236	// do nothing...
237	// we just want to leave it as -1
238	// -- actually, maybe we want to do more checks in here?
239	// although in this code context it'll probably be ok,
240	// it might be worth verifying wildcards and that the
241	// number is in range...
242	}
243	}
244	return ipaddr;
245	}
246
247	/**
248	* Compares two short arrays. The first array can contain a -1,
249	* which will always match any value -- it's a wildcard.
250	* They must be the same length to match.
251	*
252	* @param first The first array to compare (with -1 wildcard if required)
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	if(first[i] == -1) {
262	continue;
263	}
264	if(first[i] != second[i]) {
265	return false;
266	}
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	}