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 
PortFilter(int lowerBound, int upperBound)38     private PortFilter(int lowerBound, int upperBound) {
39         mLowerBound = lowerBound;
40         mUpperBound = upperBound;
41     }
42 
43     @Override
matches(IntentFirewall ifw, ComponentName resolvedComponent, Intent intent, int callerUid, int callerPid, String resolvedType, int receivingUid)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