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 1.12 2002/01/08 13:31:34 tdb Exp $
 */
public class ACL implements Serializable {

//---FINAL ATTRIBUTES---

    /**
     * The current CVS revision of this class
     */
    public static final String REVISION = "$Revision: 1.12 $";
    
    /**
     * 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:	1.1
Committed:	Tue Jan 8 14:24:28 2002 UTC (22 years, 3 months ago) by tdb
Branch:	MAIN
Branch point for:	SERVER_PIRCBOT
Log Message:	Merged ACL code into the util package. This code was previously in CVS:experimental/server/ACL.
#	User	Rev	Content
1	tdb	1.1	//---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 1.12 2002/01/08 13:31:34 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: 1.12 $";
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			//---PUBLIC METHODS---
66
67			/**
68			* Add a new rule to the ACL immediately after the
69			* previous rule. The rule can either be an ACL.ALLOW
70			* rule, or an ACL.DENY rule. The expression can
71			* contain a wildcard (a * only). Rules can only be
72			* added to the end of the list.
73			*
74			* param allow whether this is an ALLOW or DENY rule
75			* param expression what this rule matches using wildcards
76			*/
77			public void add(boolean allow, String expression) {
78			// try and convert the expression into an IP address
79			short[] ipaddr = ipStringToShort(expression);
80			// a result of null means it's not an IP address
81			// add either a name rule or an IP rule
82			if(ipaddr != null) {
83			_acl.add(new ACLRule(allow, expression, ipaddr, true));
84			}
85			else {
86			_acl.add(new ACLRule(allow, expression, ipaddr, false));
87			}
88			}
89
90			/**
91			* Check to see if a string is permitted by the
92			* ACL. Useful for testing, and non-Socket uses
93			* of this class.
94			*
95			* @param address the string to check
96			* @return whether the address was permitted by the ACL
97			*/
98			public boolean check(String address) {
99			for(int i=0; i < _acl.size(); i++) {
100			ACLRule rule = (ACLRule) _acl.get(i);
101			if(StringUtils.wildcardMatch(address, rule._expression)) {
102			return rule._allow;
103			}
104			}
105			return _defaultMode;
106			}
107
108			/**
109			* Check to see if an InetAddress is permitted
110			* by the ACL. Perfect for Socket uses of this
111			* class. A rule will either be for a name, or
112			* an IP address (this is determined in the add
113			* method), and the appropriate comparison will
114			* be performed.
115			*
116			* @param address the InetAddress to check
117			* @return whether the InetAddress was permitted by the ACL
118			*/
119			public boolean check(InetAddress address) {
120			// gather the details first
121			String hostname = address.getHostName();
122			String ip = address.getHostAddress();
123			short[] ipaddr = ipStringToShort(ip);
124			// check each rule against this InetAddress
125			for(int i=0; i < _acl.size(); i++) {
126			ACLRule rule = (ACLRule) _acl.get(i);
127			if(rule._iprule) {
128			// if this is an IP rule do a short comparison
129			// must specify the wildcarded rule first
130			if(compareShorts(rule._ipaddr, ipaddr)) {
131			return rule._allow;
132			}
133			}
134			else {
135			// if not do a full blown String comparsion
136			if(StringUtils.wildcardMatch(hostname, rule._expression)) {
137			return rule._allow;
138			}
139			}
140
141			}
142			// if we haven't matched a rule, return the default
143			return _defaultMode;
144			}
145
146			/**
147			* Gives a String representation of this ACL.
148			*
149			* @return A String representation of this ACL.
150			*/
151			public String toString() {
152			StringBuffer acl = new StringBuffer();
153			// put in the i-scream toString code
154			acl.append(FormatName.getName(_name, getClass().getName(), REVISION));
155			acl.append("{");
156			// put the value of each Rule in the result
157			for(int i=0; i < _acl.size(); i++) {
158			acl.append((ACLRule) _acl.get(i));
159			acl.append(",");
160			}
161			// put the default mode in the result
162			if(_defaultMode) {
163			acl.append("DEFAULT=ALLOW");
164			}
165			else {
166			acl.append("DEFAULT=DENY");
167			}
168			acl.append("}");
169			return acl.toString();
170			}
171
172			//---PRIVATE METHODS---
173
174			/**
175			* Converts an IP address in String format into
176			* a short array of length 4. Any wildcards, *,
177			* found in the IP address are represented by
178			* a -1. If the given String is not an IP address
179			* null is returned instead.
180			*
181			* @param ip The IP address in String format
182			* @return The IP address in a short[]
183			*/
184			private short[] ipStringToShort(String ip) {
185			// default to expecting it to be an IP
186			// we will try to disprove this :)
187			short[] ipaddr = {-1, -1, -1, -1};
188			int i = 0;
189			String s = "";
190			// tokenize the String on fullstops, so we can break
191			// up the quads of an IP (if it's an IP!)
192			StringTokenizer st = new StringTokenizer(ip, ".");
193			while(st.hasMoreTokens() && i++ < 4) {
194			s = st.nextToken();
195			// if it's a wildcard, we'll skip to the next one
196			// as no more checks are required
197			if(s.equals("*")) {
198			continue;
199			}
200			// attempt to parse it into a short
201			try {
202			short n = Short.parseShort(s);
203			// if it's an int but outside of the
204			// valid range, it can't be an IP
205			if(n < 0 \|\| n > 255) {
206			// give up checking further
207			return null;
208			}
209			ipaddr[i-1] = n;
210			}
211			// if it didn't parse as a short it can't be an IP
212			catch (NumberFormatException e) {
213			// give up checking further
214			return null;
215			}
216			}
217			// we've done 4 parts, so if there's any
218			// more this can't be an IP
219			if(st.hasMoreTokens()) {
220			return null;
221			}
222			// if we've done less than 4, see if the last one
223			// was a wildcard - if it isn't then it's not an IP
224			// -- this allows 129.12.*
225			if(i < 4 && !s.equals("*")) {
226			return null;
227			}
228			// if we had one or less entries it can't be an IP
229			// -- this disallows * matching as an IP due
230			// to the rule above
231			if(i <= 1) {
232			return null;
233			}
234			return ipaddr;
235			}
236
237			/**
238			* Compares two short arrays. The first array can contain a -1,
239			* which will always match any value -- it's a wildcard.
240			* They must be the same length to match.
241			*
242			* @param first The first array to compare (with -1 wildcard if required)
243			* @param second The second array to compare
244			* @result the result of the comparison
245			*/
246			private boolean compareShorts(short[] first, short[] second) {
247			if(first.length != second.length) {
248			return false;
249			}
250			for(int i=0; i < first.length; i++) {
251			if(first[i] == -1) {
252			continue;
253			}
254			if(first[i] != second[i]) {
255			return false;
256			}
257			}
258			return true;
259			}
260
261			//---ACCESSOR/MUTATOR METHODS---
262
263			//---ATTRIBUTES---
264
265			/**
266			* This is the friendly identifier of the
267			* component this class is running in.
268			* eg, a Filter may be called "filter1",
269			* If this class does not have an owning
270			* component, a name from the configuration
271			* can be placed here. This name could also
272			* be changed to null for utility classes.
273			*/
274			private String _name = null;
275
276			/**
277			* The ACL is stored in this ArrayList.
278			*/
279			private ArrayList _acl = new ArrayList();
280
281			/**
282			* The default mode of this ACL.
283			*/
284			private boolean _defaultMode;
285
286			//---STATIC ATTRIBUTES---
287
288			//---INNER CLASSES---
289
290			/**
291			* Wrapper class for an ACL rule.
292			*/
293			private class ACLRule implements Serializable {
294
295			/**
296			* Construct an ACL rule.
297			*
298			* @param allow whether this is an ALLOW or DENY rule
299			* @param expression what this rule matches
300			* @param ipaddr the IP address wildcard this rule matches if it's an IP rule
301			* @param iprule whether this is an IP rule
302			*/
303			private ACLRule(boolean allow, String expression, short[] ipaddr, boolean iprule) {
304			_allow = allow;
305			_expression = expression;
306			_ipaddr = ipaddr;
307			_iprule = iprule;
308			}
309
310			/**
311			* Returns a String representation of this rule.
312			*
313			* @return A String representation of this rule.
314			*/
315			public String toString() {
316			if(_allow) {
317			return _expression + "=ALLOW";
318			}
319			else {
320			return _expression + "=DENY";
321			}
322			}
323
324			/**
325			* Whether this is an ALLOW or DENY rule.
326			*/
327			private boolean _allow;
328
329			/**
330			* What this rule matches.
331			*/
332			private String _expression;
333
334			/**
335			* The IP wildcard, only valid if this
336			* is an IP rule.
337			*/
338			private short[] _ipaddr;
339
340			/**
341			* Whether this is an IP rule.
342			*/
343			private boolean _iprule;
344
345			}
346
347			}