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/*
 * Copyright 2012 The Netty Project
 *
 * The Netty Project licenses this file to you under the Apache License,
 * version 2.0 (the "License"); you may not use this file except in compliance
 * with the License. You may obtain a copy of the License at:
 *
 *   http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
 * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
 * License for the specific language governing permissions and limitations
 * under the License.
 */
package org.jboss.netty.handler.ipfilter;

import org.jboss.netty.logging.InternalLogger;
import org.jboss.netty.logging.InternalLoggerFactory;
import org.jboss.netty.util.internal.StringUtil;

import java.net.UnknownHostException;
import java.util.ArrayList;

/**
 * The Class IpFilterRuleList is a helper class to generate a List of Rules from a string.
 * In case of parse errors no exceptions are thrown. The error is logged.
 * 

 * Rule List Syntax:
 * 

 *  * RuleList ::= Rule[,Rule]*
 * Rule ::= AllowRule | BlockRule
 * AllowRule ::= +Filter
 * BlockRule ::= -Filter
 * Filter ::= PatternFilter | CIDRFilter
 * PatternFilter ::= @see PatternRule
 * CIDRFilter ::= c:CIDRFilter
 * CIDRFilter ::= @see CIDR.newCIDR(String)
 * 
 * 

 * Example: allow only localhost:
 * 

 * new IPFilterRuleHandler().addAll(new IpFilterRuleList("+n:localhost, -n:*"));
 * 

 */
public class IpFilterRuleList extends ArrayList {
    private static final long serialVersionUID = -6164162941749588780L;

    private static final InternalLogger logger = InternalLoggerFactory.getInstance(IpFilterRuleList.class);

    /**
     * Instantiates a new ip filter rule list.
     *
     * @param rules the rules
     */
    public IpFilterRuleList(String rules) {
        parseRules(rules);
    }

    private void parseRules(String rules) {
        String[] ruless = StringUtil.split(rules, ',');
        for (String rule : ruless) {
            parseRule(rule.trim());
        }
    }

    private void parseRule(String rule) {
        if (rule == null || rule.length() == 0) {
            return;
        }
        if (!(rule.startsWith("+") || rule.startsWith("-"))) {
            if (logger.isErrorEnabled()) {
                logger.error("syntax error in ip filter rule:" + rule);
            }
            return;
        }

        boolean allow = rule.startsWith("+");
        if (rule.charAt(1) == 'n' || rule.charAt(1) == 'i') {
            add(new PatternRule(allow, rule.substring(1)));
        } else if (rule.charAt(1) == 'c') {
            try {
                add(new IpSubnetFilterRule(allow, rule.substring(3)));
            } catch (UnknownHostException e) {
                if (logger.isErrorEnabled()) {
                    logger.error("error parsing ip filter " + rule, e);
                }
            }
        } else {
            if (logger.isErrorEnabled()) {
                logger.error("syntax error in ip filter rule:" + rule);
            }
        }
    }
}