1 /* 2 * Copyright (C) 2014 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 package com.android.nfc; 17 18 19 import android.app.ActivityManager; 20 import android.content.Context; 21 import android.content.Intent; 22 import android.net.wifi.WifiConfiguration; 23 import android.nfc.NdefMessage; 24 import android.nfc.NdefRecord; 25 import android.nfc.tech.Ndef; 26 import android.os.UserHandle; 27 import android.os.UserManager; 28 import android.util.Log; 29 30 import java.nio.BufferUnderflowException; 31 import java.nio.ByteBuffer; 32 import java.util.Arrays; 33 import java.util.BitSet; 34 35 public final class NfcWifiProtectedSetup { 36 37 public static final String NFC_TOKEN_MIME_TYPE = "application/vnd.wfa.wsc"; 38 39 public static final String EXTRA_WIFI_CONFIG = "com.android.nfc.WIFI_CONFIG_EXTRA"; 40 41 /* 42 * ID into configuration record for SSID and Network Key in hex. 43 * Obtained from WFA Wifi Simple Configuration Technical Specification v2.0.2.1. 44 */ 45 private static final short CREDENTIAL_FIELD_ID = 0x100E; 46 private static final short SSID_FIELD_ID = 0x1045; 47 private static final short NETWORK_KEY_FIELD_ID = 0x1027; 48 private static final short AUTH_TYPE_FIELD_ID = 0x1003; 49 50 private static final short AUTH_TYPE_EXPECTED_SIZE = 2; 51 52 private static final short AUTH_TYPE_OPEN = 0x0001; 53 private static final short AUTH_TYPE_WPA_PSK = 0x0002; 54 private static final short AUTH_TYPE_WPA_EAP = 0x0008; 55 private static final short AUTH_TYPE_WPA2_EAP = 0x0010; 56 private static final short AUTH_TYPE_WPA2_PSK = 0x0020; 57 private static final short AUTH_TYPE_WPA_AND_WPA2_PSK = 0x0022; 58 59 private static final int MAX_NETWORK_KEY_SIZE_BYTES = 64; 60 NfcWifiProtectedSetup()61 private NfcWifiProtectedSetup() {} 62 tryNfcWifiSetup(Ndef ndef, Context context)63 public static boolean tryNfcWifiSetup(Ndef ndef, Context context) { 64 65 if (ndef == null || context == null) { 66 return false; 67 } 68 69 NdefMessage cachedNdefMessage = ndef.getCachedNdefMessage(); 70 if (cachedNdefMessage == null) { 71 return false; 72 } 73 74 final WifiConfiguration wifiConfiguration; 75 try { 76 wifiConfiguration = parse(cachedNdefMessage); 77 } catch (BufferUnderflowException e) { 78 // malformed payload 79 return false; 80 } 81 82 if (wifiConfiguration != null &&!UserManager.get(context).hasUserRestriction( 83 UserManager.DISALLOW_CONFIG_WIFI, 84 // hasUserRestriction does not support UserHandle.CURRENT. 85 UserHandle.of(ActivityManager.getCurrentUser()))) { 86 Intent configureNetworkIntent = new Intent() 87 .putExtra(EXTRA_WIFI_CONFIG, wifiConfiguration) 88 .setClass(context, ConfirmConnectToWifiNetworkActivity.class) 89 .setFlags(Intent.FLAG_ACTIVITY_NEW_TASK | Intent.FLAG_ACTIVITY_CLEAR_TASK); 90 91 context.startActivityAsUser(configureNetworkIntent, UserHandle.CURRENT); 92 return true; 93 } 94 95 return false; 96 } 97 parse(NdefMessage message)98 private static WifiConfiguration parse(NdefMessage message) { 99 NdefRecord[] records = message.getRecords(); 100 101 for (NdefRecord record : records) { 102 if (new String(record.getType()).equals(NFC_TOKEN_MIME_TYPE)) { 103 ByteBuffer payload = ByteBuffer.wrap(record.getPayload()); 104 while (payload.hasRemaining()) { 105 short fieldId = payload.getShort(); 106 int fieldSize = payload.getShort() & 0xFFFF; 107 if (fieldId == CREDENTIAL_FIELD_ID) { 108 return parseCredential(payload, fieldSize); 109 } 110 payload.position(payload.position() + fieldSize); 111 } 112 } 113 } 114 return null; 115 } 116 parseCredential(ByteBuffer payload, int size)117 private static WifiConfiguration parseCredential(ByteBuffer payload, int size) { 118 int startPosition = payload.position(); 119 WifiConfiguration result = new WifiConfiguration(); 120 while (payload.position() < startPosition + size) { 121 short fieldId = payload.getShort(); 122 int fieldSize = payload.getShort() & 0xFFFF; 123 124 // Quick check 125 if (payload.position() + fieldSize > startPosition + size) { 126 return null; 127 } 128 129 switch (fieldId) { 130 case SSID_FIELD_ID: 131 byte[] ssid = new byte[fieldSize]; 132 payload.get(ssid); 133 result.SSID = "\"" + new String(ssid) + "\""; 134 break; 135 case NETWORK_KEY_FIELD_ID: 136 if (fieldSize > MAX_NETWORK_KEY_SIZE_BYTES) { 137 return null; 138 } 139 byte[] networkKey = new byte[fieldSize]; 140 payload.get(networkKey); 141 if (fieldSize > 0) { 142 result.preSharedKey = getPskValidFormat(new String(networkKey)); 143 } 144 break; 145 case AUTH_TYPE_FIELD_ID: 146 if (fieldSize != AUTH_TYPE_EXPECTED_SIZE) { 147 // corrupt data 148 return null; 149 } 150 151 short authType = payload.getShort(); 152 populateAllowedKeyManagement(result.allowedKeyManagement, authType); 153 break; 154 default: 155 // unknown / unparsed tag 156 payload.position(payload.position() + fieldSize); 157 break; 158 } 159 } 160 161 if (result.SSID != null) { 162 if (result.getAuthType() == WifiConfiguration.KeyMgmt.NONE) { 163 if (result.preSharedKey == null) { 164 return result; 165 } 166 } else { 167 if (result.preSharedKey != null) { 168 return result; 169 } 170 } 171 } 172 173 return null; 174 } 175 populateAllowedKeyManagement(BitSet allowedKeyManagement, short authType)176 private static void populateAllowedKeyManagement(BitSet allowedKeyManagement, short authType) { 177 if (authType == AUTH_TYPE_WPA_PSK || authType == AUTH_TYPE_WPA2_PSK 178 || authType == AUTH_TYPE_WPA_AND_WPA2_PSK) { 179 allowedKeyManagement.set(WifiConfiguration.KeyMgmt.WPA_PSK); 180 } else if (authType == AUTH_TYPE_WPA_EAP || authType == AUTH_TYPE_WPA2_EAP) { 181 allowedKeyManagement.set(WifiConfiguration.KeyMgmt.WPA_EAP); 182 } else if (authType == AUTH_TYPE_OPEN) { 183 allowedKeyManagement.set(WifiConfiguration.KeyMgmt.NONE); 184 } 185 } 186 getPskValidFormat(String data)187 private static String getPskValidFormat(String data) { 188 if (!data.matches("[0-9A-Fa-f]{64}")) { // if not HEX string 189 data = convertToQuotedString(data); 190 } 191 return data; 192 } 193 convertToQuotedString(String str)194 private static String convertToQuotedString(String str) { 195 return '"' + str + '"'; 196 } 197 } 198