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      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 
     17 package com.android.server.connectivity.tethering;
     18 
     19 import static android.content.Context.TELEPHONY_SERVICE;
     20 import static android.net.ConnectivityManager.TYPE_ETHERNET;
     21 import static android.net.ConnectivityManager.TYPE_MOBILE;
     22 import static android.net.ConnectivityManager.TYPE_MOBILE_DUN;
     23 import static android.net.ConnectivityManager.TYPE_MOBILE_HIPRI;
     24 
     25 import android.content.Context;
     26 import android.content.res.Resources;
     27 import android.net.ConnectivityManager;
     28 import android.telephony.TelephonyManager;
     29 import android.net.util.SharedLog;
     30 
     31 import java.io.PrintWriter;
     32 import java.util.ArrayList;
     33 import java.util.Arrays;
     34 import java.util.Collection;
     35 import java.util.StringJoiner;
     36 
     37 
     38 /**
     39  * A utility class to encapsulate the various tethering configuration elements.
     40  *
     41  * This configuration data includes elements describing upstream properties
     42  * (preferred and required types of upstream connectivity as well as default
     43  * DNS servers to use if none are available) and downstream properties (such
     44  * as regular expressions use to match suitable downstream interfaces and the
     45  * DHCPv4 ranges to use).
     46  *
     47  * @hide
     48  */
     49 public class TetheringConfiguration {
     50     private static final String TAG = TetheringConfiguration.class.getSimpleName();
     51 
     52     public static final int DUN_NOT_REQUIRED = 0;
     53     public static final int DUN_REQUIRED = 1;
     54     public static final int DUN_UNSPECIFIED = 2;
     55 
     56     // USB is  192.168.42.1 and 255.255.255.0
     57     // Wifi is 192.168.43.1 and 255.255.255.0
     58     // BT is limited to max default of 5 connections. 192.168.44.1 to 192.168.48.1
     59     // with 255.255.255.0
     60     // P2P is 192.168.49.1 and 255.255.255.0
     61     private static final String[] DHCP_DEFAULT_RANGE = {
     62         "192.168.42.2", "192.168.42.254", "192.168.43.2", "192.168.43.254",
     63         "192.168.44.2", "192.168.44.254", "192.168.45.2", "192.168.45.254",
     64         "192.168.46.2", "192.168.46.254", "192.168.47.2", "192.168.47.254",
     65         "192.168.48.2", "192.168.48.254", "192.168.49.2", "192.168.49.254",
     66     };
     67 
     68     private final String[] DEFAULT_IPV4_DNS = {"8.8.4.4", "8.8.8.8"};
     69 
     70     public final String[] tetherableUsbRegexs;
     71     public final String[] tetherableWifiRegexs;
     72     public final String[] tetherableBluetoothRegexs;
     73     public final int dunCheck;
     74     public final boolean isDunRequired;
     75     public final Collection<Integer> preferredUpstreamIfaceTypes;
     76     public final String[] dhcpRanges;
     77     public final String[] defaultIPv4DNS;
     78 
     79     public TetheringConfiguration(Context ctx, SharedLog log) {
     80         final SharedLog configLog = log.forSubComponent("config");
     81 
     82         tetherableUsbRegexs = ctx.getResources().getStringArray(
     83                 com.android.internal.R.array.config_tether_usb_regexs);
     84         // TODO: Evaluate deleting this altogether now that Wi-Fi always passes
     85         // us an interface name. Careful consideration needs to be given to
     86         // implications for Settings and for provisioning checks.
     87         tetherableWifiRegexs = ctx.getResources().getStringArray(
     88                 com.android.internal.R.array.config_tether_wifi_regexs);
     89         tetherableBluetoothRegexs = ctx.getResources().getStringArray(
     90                 com.android.internal.R.array.config_tether_bluetooth_regexs);
     91 
     92         dunCheck = checkDunRequired(ctx);
     93         configLog.log("DUN check returned: " + dunCheckString(dunCheck));
     94 
     95         preferredUpstreamIfaceTypes = getUpstreamIfaceTypes(ctx, dunCheck);
     96         isDunRequired = preferredUpstreamIfaceTypes.contains(TYPE_MOBILE_DUN);
     97 
     98         dhcpRanges = getDhcpRanges(ctx);
     99         defaultIPv4DNS = copy(DEFAULT_IPV4_DNS);
    100 
    101         configLog.log(toString());
    102     }
    103 
    104     public boolean isUsb(String iface) {
    105         return matchesDownstreamRegexs(iface, tetherableUsbRegexs);
    106     }
    107 
    108     public boolean isWifi(String iface) {
    109         return matchesDownstreamRegexs(iface, tetherableWifiRegexs);
    110     }
    111 
    112     public boolean isBluetooth(String iface) {
    113         return matchesDownstreamRegexs(iface, tetherableBluetoothRegexs);
    114     }
    115 
    116     public void dump(PrintWriter pw) {
    117         dumpStringArray(pw, "tetherableUsbRegexs", tetherableUsbRegexs);
    118         dumpStringArray(pw, "tetherableWifiRegexs", tetherableWifiRegexs);
    119         dumpStringArray(pw, "tetherableBluetoothRegexs", tetherableBluetoothRegexs);
    120 
    121         pw.print("isDunRequired: ");
    122         pw.println(isDunRequired);
    123 
    124         dumpStringArray(pw, "preferredUpstreamIfaceTypes",
    125                 preferredUpstreamNames(preferredUpstreamIfaceTypes));
    126 
    127         dumpStringArray(pw, "dhcpRanges", dhcpRanges);
    128         dumpStringArray(pw, "defaultIPv4DNS", defaultIPv4DNS);
    129     }
    130 
    131     public String toString() {
    132         final StringJoiner sj = new StringJoiner(" ");
    133         sj.add(String.format("tetherableUsbRegexs:%s", makeString(tetherableUsbRegexs)));
    134         sj.add(String.format("tetherableWifiRegexs:%s", makeString(tetherableWifiRegexs)));
    135         sj.add(String.format("tetherableBluetoothRegexs:%s",
    136                 makeString(tetherableBluetoothRegexs)));
    137         sj.add(String.format("isDunRequired:%s", isDunRequired));
    138         sj.add(String.format("preferredUpstreamIfaceTypes:%s",
    139                 makeString(preferredUpstreamNames(preferredUpstreamIfaceTypes))));
    140         return String.format("TetheringConfiguration{%s}", sj.toString());
    141     }
    142 
    143     private static void dumpStringArray(PrintWriter pw, String label, String[] values) {
    144         pw.print(label);
    145         pw.print(": ");
    146 
    147         if (values != null) {
    148             final StringJoiner sj = new StringJoiner(", ", "[", "]");
    149             for (String value : values) { sj.add(value); }
    150             pw.print(sj.toString());
    151         } else {
    152             pw.print("null");
    153         }
    154 
    155         pw.println();
    156     }
    157 
    158     private static String makeString(String[] strings) {
    159         final StringJoiner sj = new StringJoiner(",", "[", "]");
    160         for (String s : strings) sj.add(s);
    161         return sj.toString();
    162     }
    163 
    164     private static String[] preferredUpstreamNames(Collection<Integer> upstreamTypes) {
    165         String[] upstreamNames = null;
    166 
    167         if (upstreamTypes != null) {
    168             upstreamNames = new String[upstreamTypes.size()];
    169             int i = 0;
    170             for (Integer netType : upstreamTypes) {
    171                 upstreamNames[i] = ConnectivityManager.getNetworkTypeName(netType);
    172                 i++;
    173             }
    174         }
    175 
    176         return upstreamNames;
    177     }
    178 
    179     public static int checkDunRequired(Context ctx) {
    180         final TelephonyManager tm = (TelephonyManager) ctx.getSystemService(TELEPHONY_SERVICE);
    181         return (tm != null) ? tm.getTetherApnRequired() : DUN_UNSPECIFIED;
    182     }
    183 
    184     private static String dunCheckString(int dunCheck) {
    185         switch (dunCheck) {
    186             case DUN_NOT_REQUIRED: return "DUN_NOT_REQUIRED";
    187             case DUN_REQUIRED:     return "DUN_REQUIRED";
    188             case DUN_UNSPECIFIED:  return "DUN_UNSPECIFIED";
    189             default:
    190                 return String.format("UNKNOWN (%s)", dunCheck);
    191         }
    192     }
    193 
    194     private static Collection<Integer> getUpstreamIfaceTypes(Context ctx, int dunCheck) {
    195         final int ifaceTypes[] = ctx.getResources().getIntArray(
    196                 com.android.internal.R.array.config_tether_upstream_types);
    197         final ArrayList<Integer> upstreamIfaceTypes = new ArrayList<>(ifaceTypes.length);
    198         for (int i : ifaceTypes) {
    199             switch (i) {
    200                 case TYPE_MOBILE:
    201                 case TYPE_MOBILE_HIPRI:
    202                     if (dunCheck == DUN_REQUIRED) continue;
    203                     break;
    204                 case TYPE_MOBILE_DUN:
    205                     if (dunCheck == DUN_NOT_REQUIRED) continue;
    206                     break;
    207             }
    208             upstreamIfaceTypes.add(i);
    209         }
    210 
    211         // Fix up upstream interface types for DUN or mobile. NOTE: independent
    212         // of the value of |dunCheck|, cell data of one form or another is
    213         // *always* an upstream, regardless of the upstream interface types
    214         // specified by configuration resources.
    215         if (dunCheck == DUN_REQUIRED) {
    216             appendIfNotPresent(upstreamIfaceTypes, TYPE_MOBILE_DUN);
    217         } else if (dunCheck == DUN_NOT_REQUIRED) {
    218             appendIfNotPresent(upstreamIfaceTypes, TYPE_MOBILE);
    219             appendIfNotPresent(upstreamIfaceTypes, TYPE_MOBILE_HIPRI);
    220         } else {
    221             // Fix upstream interface types for case DUN_UNSPECIFIED.
    222             // Do not modify if a cellular interface type is already present in the
    223             // upstream interface types. Add TYPE_MOBILE and TYPE_MOBILE_HIPRI if no
    224             // cellular interface types are found in the upstream interface types.
    225             if (!(containsOneOf(upstreamIfaceTypes,
    226                     TYPE_MOBILE_DUN, TYPE_MOBILE, TYPE_MOBILE_HIPRI))) {
    227                 upstreamIfaceTypes.add(TYPE_MOBILE);
    228                 upstreamIfaceTypes.add(TYPE_MOBILE_HIPRI);
    229             }
    230         }
    231 
    232         // Always make sure our good friend Ethernet is present.
    233         // TODO: consider unilaterally forcing this at the front.
    234         prependIfNotPresent(upstreamIfaceTypes, TYPE_ETHERNET);
    235 
    236         return upstreamIfaceTypes;
    237     }
    238 
    239     private static boolean matchesDownstreamRegexs(String iface, String[] regexs) {
    240         for (String regex : regexs) {
    241             if (iface.matches(regex)) return true;
    242         }
    243         return false;
    244     }
    245 
    246     private static String[] getDhcpRanges(Context ctx) {
    247         final String[] fromResource = ctx.getResources().getStringArray(
    248                 com.android.internal.R.array.config_tether_dhcp_range);
    249         if ((fromResource.length > 0) && (fromResource.length % 2 == 0)) {
    250             return fromResource;
    251         }
    252         return copy(DHCP_DEFAULT_RANGE);
    253     }
    254 
    255     private static String[] copy(String[] strarray) {
    256         return Arrays.copyOf(strarray, strarray.length);
    257     }
    258 
    259     private static void prependIfNotPresent(ArrayList<Integer> list, int value) {
    260         if (list.contains(value)) return;
    261         list.add(0, value);
    262     }
    263 
    264     private static void appendIfNotPresent(ArrayList<Integer> list, int value) {
    265         if (list.contains(value)) return;
    266         list.add(value);
    267     }
    268 
    269     private static boolean containsOneOf(ArrayList<Integer> list, Integer... values) {
    270         for (Integer value : values) {
    271             if (list.contains(value)) return true;
    272         }
    273         return false;
    274     }
    275 }
    276