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      1 /*
      2  * Copyright (C) 2013 The Android Open Source Project
      3  *
      4  * Licensed under the Apache License, Version 2.0 (the "License");
      5  * you may not use this file except in compliance with the License.
      6  * You may obtain a copy of the License at
      7  *
      8  *      http://www.apache.org/licenses/LICENSE-2.0
      9  *
     10  * Unless required by applicable law or agreed to in writing, software
     11  * distributed under the License is distributed on an "AS IS" BASIS,
     12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
     13  * See the License for the specific language governing permissions and
     14  * limitations under the License.
     15  */
     16 
     17 package com.android.server.firewall;
     18 
     19 import android.content.ComponentName;
     20 import android.content.Intent;
     21 import android.net.Uri;
     22 import org.xmlpull.v1.XmlPullParser;
     23 import org.xmlpull.v1.XmlPullParserException;
     24 
     25 import java.io.IOException;
     26 
     27 class PortFilter implements Filter {
     28     private static final String ATTR_EQUALS = "equals";
     29     private static final String ATTR_MIN = "min";
     30     private static final String ATTR_MAX = "max";
     31 
     32     private static final int NO_BOUND = -1;
     33 
     34     // both bounds are inclusive
     35     private final int mLowerBound;
     36     private final int mUpperBound;
     37 
     38     private PortFilter(int lowerBound, int upperBound) {
     39         mLowerBound = lowerBound;
     40         mUpperBound = upperBound;
     41     }
     42 
     43     @Override
     44     public boolean matches(IntentFirewall ifw, ComponentName resolvedComponent, Intent intent,
     45             int callerUid, int callerPid, String resolvedType, int receivingUid) {
     46         int port = -1;
     47         Uri uri = intent.getData();
     48         if (uri != null) {
     49             port = uri.getPort();
     50         }
     51         return port != -1 &&
     52                 (mLowerBound == NO_BOUND || mLowerBound <= port) &&
     53                 (mUpperBound == NO_BOUND || mUpperBound >= port);
     54     }
     55 
     56     public static final FilterFactory FACTORY = new FilterFactory("port") {
     57         @Override
     58         public Filter newFilter(XmlPullParser parser)
     59                 throws IOException, XmlPullParserException {
     60             int lowerBound = NO_BOUND;
     61             int upperBound = NO_BOUND;
     62 
     63             String equalsValue = parser.getAttributeValue(null, ATTR_EQUALS);
     64             if (equalsValue != null) {
     65                 int value;
     66                 try {
     67                     value = Integer.parseInt(equalsValue);
     68                 } catch (NumberFormatException ex) {
     69                     throw new XmlPullParserException("Invalid port value: " + equalsValue,
     70                             parser, null);
     71                 }
     72                 lowerBound = value;
     73                 upperBound = value;
     74             }
     75 
     76             String lowerBoundString = parser.getAttributeValue(null, ATTR_MIN);
     77             String upperBoundString = parser.getAttributeValue(null, ATTR_MAX);
     78             if (lowerBoundString != null || upperBoundString != null) {
     79                 if (equalsValue != null) {
     80                     throw new XmlPullParserException(
     81                             "Port filter cannot use both equals and range filtering",
     82                             parser, null);
     83                 }
     84 
     85                 if (lowerBoundString != null) {
     86                     try {
     87                         lowerBound = Integer.parseInt(lowerBoundString);
     88                     } catch (NumberFormatException ex) {
     89                         throw new XmlPullParserException(
     90                                 "Invalid minimum port value: " + lowerBoundString,
     91                                 parser, null);
     92                     }
     93                 }
     94 
     95                 if (upperBoundString != null) {
     96                     try {
     97                         upperBound = Integer.parseInt(upperBoundString);
     98                     } catch (NumberFormatException ex) {
     99                         throw new XmlPullParserException(
    100                                 "Invalid maximum port value: " + upperBoundString,
    101                                 parser, null);
    102                     }
    103                 }
    104             }
    105 
    106             // an empty port filter is explicitly allowed, and checks for the existence of a port
    107             return new PortFilter(lowerBound, upperBound);
    108         }
    109     };
    110 }
    111