PortFilter.java revision 9158825f9c41869689d6b1786d7c7aa8bdd524ce 
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
17package com.android.server.firewall;
18
19import android.content.ComponentName;
20import android.content.Intent;
21import android.net.Uri;
22import org.xmlpull.v1.XmlPullParser;
23import org.xmlpull.v1.XmlPullParserException;
24
25import java.io.IOException;
26
27class 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