1/*
2 * Copyright (C) 2017 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.connectivity.tethering;
18
19import static android.content.Context.TELEPHONY_SERVICE;
20import static android.net.ConnectivityManager.TYPE_MOBILE;
21import static android.net.ConnectivityManager.TYPE_MOBILE_DUN;
22import static android.net.ConnectivityManager.TYPE_MOBILE_HIPRI;
23
24import android.content.Context;
25import android.content.res.Resources;
26import android.net.ConnectivityManager;
27import android.telephony.TelephonyManager;
28import android.util.Log;
29
30import java.io.PrintWriter;
31import java.util.ArrayList;
32import java.util.Arrays;
33import java.util.Collection;
34import java.util.StringJoiner;
35
36
37/**
38 * A utility class to encapsulate the various tethering configuration elements.
39 *
40 * This configuration data includes elements describing upstream properties
41 * (preferred and required types of upstream connectivity as well as default
42 * DNS servers to use if none are available) and downstream properties (such
43 * as regular expressions use to match suitable downstream interfaces and the
44 * DHCPv4 ranges to use).
45 *
46 * @hide
47 */
48public class TetheringConfiguration {
49    private static final String TAG = TetheringConfiguration.class.getSimpleName();
50
51    public static final int DUN_NOT_REQUIRED = 0;
52    public static final int DUN_REQUIRED = 1;
53    public static final int DUN_UNSPECIFIED = 2;
54
55    // USB is  192.168.42.1 and 255.255.255.0
56    // Wifi is 192.168.43.1 and 255.255.255.0
57    // BT is limited to max default of 5 connections. 192.168.44.1 to 192.168.48.1
58    // with 255.255.255.0
59    // P2P is 192.168.49.1 and 255.255.255.0
60    private static final String[] DHCP_DEFAULT_RANGE = {
61        "192.168.42.2", "192.168.42.254", "192.168.43.2", "192.168.43.254",
62        "192.168.44.2", "192.168.44.254", "192.168.45.2", "192.168.45.254",
63        "192.168.46.2", "192.168.46.254", "192.168.47.2", "192.168.47.254",
64        "192.168.48.2", "192.168.48.254", "192.168.49.2", "192.168.49.254",
65    };
66
67    private final String[] DEFAULT_IPV4_DNS = {"8.8.4.4", "8.8.8.8"};
68
69    public final String[] tetherableUsbRegexs;
70    public final String[] tetherableWifiRegexs;
71    public final String[] tetherableBluetoothRegexs;
72    public final boolean isDunRequired;
73    public final Collection<Integer> preferredUpstreamIfaceTypes;
74    public final String[] dhcpRanges;
75    public final String[] defaultIPv4DNS;
76
77    public TetheringConfiguration(Context ctx) {
78        tetherableUsbRegexs = ctx.getResources().getStringArray(
79                com.android.internal.R.array.config_tether_usb_regexs);
80        // TODO: Evaluate deleting this altogether now that Wi-Fi always passes
81        // us an interface name. Careful consideration needs to be given to
82        // implications for Settings and for provisioning checks.
83        tetherableWifiRegexs = ctx.getResources().getStringArray(
84                com.android.internal.R.array.config_tether_wifi_regexs);
85        tetherableBluetoothRegexs = ctx.getResources().getStringArray(
86                com.android.internal.R.array.config_tether_bluetooth_regexs);
87
88        final int dunCheck = checkDunRequired(ctx);
89        preferredUpstreamIfaceTypes = getUpstreamIfaceTypes(ctx, dunCheck);
90        isDunRequired = preferredUpstreamIfaceTypes.contains(TYPE_MOBILE_DUN);
91
92        dhcpRanges = getDhcpRanges(ctx);
93        defaultIPv4DNS = copy(DEFAULT_IPV4_DNS);
94    }
95
96    public boolean isUsb(String iface) {
97        return matchesDownstreamRegexs(iface, tetherableUsbRegexs);
98    }
99
100    public boolean isWifi(String iface) {
101        return matchesDownstreamRegexs(iface, tetherableWifiRegexs);
102    }
103
104    public boolean isBluetooth(String iface) {
105        return matchesDownstreamRegexs(iface, tetherableBluetoothRegexs);
106    }
107
108    public void dump(PrintWriter pw) {
109        dumpStringArray(pw, "tetherableUsbRegexs", tetherableUsbRegexs);
110        dumpStringArray(pw, "tetherableWifiRegexs", tetherableWifiRegexs);
111        dumpStringArray(pw, "tetherableBluetoothRegexs", tetherableBluetoothRegexs);
112
113        pw.print("isDunRequired: ");
114        pw.println(isDunRequired);
115
116        String[] upstreamTypes = null;
117        if (preferredUpstreamIfaceTypes != null) {
118            upstreamTypes = new String[preferredUpstreamIfaceTypes.size()];
119            int i = 0;
120            for (Integer netType : preferredUpstreamIfaceTypes) {
121                upstreamTypes[i] = ConnectivityManager.getNetworkTypeName(netType);
122                i++;
123            }
124        }
125        dumpStringArray(pw, "preferredUpstreamIfaceTypes", upstreamTypes);
126
127        dumpStringArray(pw, "dhcpRanges", dhcpRanges);
128        dumpStringArray(pw, "defaultIPv4DNS", defaultIPv4DNS);
129    }
130
131    private static void dumpStringArray(PrintWriter pw, String label, String[] values) {
132        pw.print(label);
133        pw.print(": ");
134
135        if (values != null) {
136            final StringJoiner sj = new StringJoiner(", ", "[", "]");
137            for (String value : values) { sj.add(value); }
138            pw.print(sj.toString());
139        } else {
140            pw.print("null");
141        }
142
143        pw.println();
144    }
145
146    private static int checkDunRequired(Context ctx) {
147        final TelephonyManager tm = (TelephonyManager) ctx.getSystemService(TELEPHONY_SERVICE);
148        return (tm != null) ? tm.getTetherApnRequired() : DUN_UNSPECIFIED;
149    }
150
151    private static Collection<Integer> getUpstreamIfaceTypes(Context ctx, int dunCheck) {
152        final int ifaceTypes[] = ctx.getResources().getIntArray(
153                com.android.internal.R.array.config_tether_upstream_types);
154        final ArrayList<Integer> upstreamIfaceTypes = new ArrayList<>(ifaceTypes.length);
155        for (int i : ifaceTypes) {
156            switch (i) {
157                case TYPE_MOBILE:
158                case TYPE_MOBILE_HIPRI:
159                    if (dunCheck == DUN_REQUIRED) continue;
160                    break;
161                case TYPE_MOBILE_DUN:
162                    if (dunCheck == DUN_NOT_REQUIRED) continue;
163                    break;
164            }
165            upstreamIfaceTypes.add(i);
166        }
167
168        // Fix up upstream interface types for DUN or mobile. NOTE: independent
169        // of the value of |dunCheck|, cell data of one form or another is
170        // *always* an upstream, regardless of the upstream interface types
171        // specified by configuration resources.
172        if (dunCheck == DUN_REQUIRED) {
173            if (!upstreamIfaceTypes.contains(TYPE_MOBILE_DUN)) {
174                upstreamIfaceTypes.add(TYPE_MOBILE_DUN);
175            }
176        } else if (dunCheck == DUN_NOT_REQUIRED) {
177            if (!upstreamIfaceTypes.contains(TYPE_MOBILE)) {
178                upstreamIfaceTypes.add(TYPE_MOBILE);
179            }
180            if (!upstreamIfaceTypes.contains(TYPE_MOBILE_HIPRI)) {
181                upstreamIfaceTypes.add(TYPE_MOBILE_HIPRI);
182            }
183        } else {
184            // Fix upstream interface types for case DUN_UNSPECIFIED.
185            // Do not modify if a cellular interface type is already present in the
186            // upstream interface types. Add TYPE_MOBILE and TYPE_MOBILE_HIPRI if no
187            // cellular interface types are found in the upstream interface types.
188            if (!(upstreamIfaceTypes.contains(TYPE_MOBILE_DUN)
189                    || upstreamIfaceTypes.contains(TYPE_MOBILE)
190                    || upstreamIfaceTypes.contains(TYPE_MOBILE_HIPRI))) {
191                upstreamIfaceTypes.add(TYPE_MOBILE);
192                upstreamIfaceTypes.add(TYPE_MOBILE_HIPRI);
193            }
194        }
195
196        return upstreamIfaceTypes;
197    }
198
199    private static boolean matchesDownstreamRegexs(String iface, String[] regexs) {
200        for (String regex : regexs) {
201            if (iface.matches(regex)) return true;
202        }
203        return false;
204    }
205
206    private static String[] getDhcpRanges(Context ctx) {
207        final String[] fromResource = ctx.getResources().getStringArray(
208                com.android.internal.R.array.config_tether_dhcp_range);
209        if ((fromResource.length > 0) && (fromResource.length % 2 == 0)) {
210            return fromResource;
211        }
212        return copy(DHCP_DEFAULT_RANGE);
213    }
214
215    private static String[] copy(String[] strarray) {
216        return Arrays.copyOf(strarray, strarray.length);
217    }
218}
219