1 /*
2  * Copyright (C) 2012 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 android.net.wifi;
18 
19 import android.os.Parcel;
20 import android.os.Parcelable;
21 
22 import java.io.ByteArrayOutputStream;
23 import java.nio.ByteBuffer;
24 import java.nio.CharBuffer;
25 import java.nio.charset.Charset;
26 import java.nio.charset.CharsetDecoder;
27 import java.nio.charset.CoderResult;
28 import java.nio.charset.CodingErrorAction;
29 import java.util.Locale;
30 
31 /**
32  * Stores SSID octets and handles conversion.
33  *
34  * For Ascii encoded string, any octet < 32 or > 127 is encoded as
35  * a "\x" followed by the hex representation of the octet.
36  * Exception chars are ", \, \e, \n, \r, \t which are escaped by a \
37  * See src/utils/common.c for the implementation in the supplicant.
38  *
39  * @hide
40  */
41 public class WifiSsid implements Parcelable {
42     private static final String TAG = "WifiSsid";
43 
44     public final ByteArrayOutputStream octets = new ByteArrayOutputStream(32);
45 
46     private static final int HEX_RADIX = 16;
47     public static final String NONE = "<unknown ssid>";
48 
WifiSsid()49     private WifiSsid() {
50     }
51 
createFromAsciiEncoded(String asciiEncoded)52     public static WifiSsid createFromAsciiEncoded(String asciiEncoded) {
53         WifiSsid a = new WifiSsid();
54         a.convertToBytes(asciiEncoded);
55         return a;
56     }
57 
createFromHex(String hexStr)58     public static WifiSsid createFromHex(String hexStr) {
59         WifiSsid a = new WifiSsid();
60         if (hexStr == null) return a;
61 
62         if (hexStr.startsWith("0x") || hexStr.startsWith("0X")) {
63             hexStr = hexStr.substring(2);
64         }
65 
66         for (int i = 0; i < hexStr.length()-1; i += 2) {
67             int val;
68             try {
69                 val = Integer.parseInt(hexStr.substring(i, i + 2), HEX_RADIX);
70             } catch(NumberFormatException e) {
71                 val = 0;
72             }
73             a.octets.write(val);
74         }
75         return a;
76     }
77 
78     /* This function is equivalent to printf_decode() at src/utils/common.c in
79      * the supplicant */
convertToBytes(String asciiEncoded)80     private void convertToBytes(String asciiEncoded) {
81         int i = 0;
82         int val = 0;
83         while (i< asciiEncoded.length()) {
84             char c = asciiEncoded.charAt(i);
85             switch (c) {
86                 case '\\':
87                     i++;
88                     switch(asciiEncoded.charAt(i)) {
89                         case '\\':
90                             octets.write('\\');
91                             i++;
92                             break;
93                         case '"':
94                             octets.write('"');
95                             i++;
96                             break;
97                         case 'n':
98                             octets.write('\n');
99                             i++;
100                             break;
101                         case 'r':
102                             octets.write('\r');
103                             i++;
104                             break;
105                         case 't':
106                             octets.write('\t');
107                             i++;
108                             break;
109                         case 'e':
110                             octets.write(27); //escape char
111                             i++;
112                             break;
113                         case 'x':
114                             i++;
115                             try {
116                                 val = Integer.parseInt(asciiEncoded.substring(i, i + 2), HEX_RADIX);
117                             } catch (NumberFormatException e) {
118                                 val = -1;
119                             }
120                             if (val < 0) {
121                                 val = Character.digit(asciiEncoded.charAt(i), HEX_RADIX);
122                                 if (val < 0) break;
123                                 octets.write(val);
124                                 i++;
125                             } else {
126                                 octets.write(val);
127                                 i += 2;
128                             }
129                             break;
130                         case '0':
131                         case '1':
132                         case '2':
133                         case '3':
134                         case '4':
135                         case '5':
136                         case '6':
137                         case '7':
138                             val = asciiEncoded.charAt(i) - '0';
139                             i++;
140                             if (asciiEncoded.charAt(i) >= '0' && asciiEncoded.charAt(i) <= '7') {
141                                 val = val * 8 + asciiEncoded.charAt(i) - '0';
142                                 i++;
143                             }
144                             if (asciiEncoded.charAt(i) >= '0' && asciiEncoded.charAt(i) <= '7') {
145                                 val = val * 8 + asciiEncoded.charAt(i) - '0';
146                                 i++;
147                             }
148                             octets.write(val);
149                             break;
150                         default:
151                             break;
152                     }
153                     break;
154                 default:
155                     octets.write(c);
156                     i++;
157                     break;
158             }
159         }
160     }
161 
162     @Override
toString()163     public String toString() {
164         byte[] ssidBytes = octets.toByteArray();
165         // Supplicant returns \x00\x00\x00\x00\x00\x00\x00\x00 hex string
166         // for a hidden access point. Make sure we maintain the previous
167         // behavior of returning empty string for this case.
168         if (octets.size() <= 0 || isArrayAllZeroes(ssidBytes)) return "";
169         // TODO: Handle conversion to other charsets upon failure
170         Charset charset = Charset.forName("UTF-8");
171         CharsetDecoder decoder = charset.newDecoder()
172                 .onMalformedInput(CodingErrorAction.REPLACE)
173                 .onUnmappableCharacter(CodingErrorAction.REPLACE);
174         CharBuffer out = CharBuffer.allocate(32);
175 
176         CoderResult result = decoder.decode(ByteBuffer.wrap(ssidBytes), out, true);
177         out.flip();
178         if (result.isError()) {
179             return NONE;
180         }
181         return out.toString();
182     }
183 
isArrayAllZeroes(byte[] ssidBytes)184     private boolean isArrayAllZeroes(byte[] ssidBytes) {
185         for (int i = 0; i< ssidBytes.length; i++) {
186             if (ssidBytes[i] != 0) return false;
187         }
188         return true;
189     }
190 
191     /** @hide */
isHidden()192     public boolean isHidden() {
193         return isArrayAllZeroes(octets.toByteArray());
194     }
195 
196     /** @hide */
getOctets()197     public byte[] getOctets() {
198         return octets.toByteArray();
199     }
200 
201     /** @hide */
getHexString()202     public String getHexString() {
203         String out = "0x";
204         byte[] ssidbytes = getOctets();
205         for (int i = 0; i < octets.size(); i++) {
206             out += String.format(Locale.US, "%02x", ssidbytes[i]);
207         }
208         return (octets.size() > 0) ? out : null;
209     }
210 
211     /** Implement the Parcelable interface {@hide} */
describeContents()212     public int describeContents() {
213         return 0;
214     }
215 
216     /** Implement the Parcelable interface {@hide} */
writeToParcel(Parcel dest, int flags)217     public void writeToParcel(Parcel dest, int flags) {
218         dest.writeInt(octets.size());
219         dest.writeByteArray(octets.toByteArray());
220     }
221 
222     /** Implement the Parcelable interface {@hide} */
223     public static final Creator<WifiSsid> CREATOR =
224         new Creator<WifiSsid>() {
225             public WifiSsid createFromParcel(Parcel in) {
226                 WifiSsid ssid = new WifiSsid();
227                 int length = in.readInt();
228                 byte b[] = new byte[length];
229                 in.readByteArray(b);
230                 ssid.octets.write(b, 0, length);
231                 return ssid;
232             }
233 
234             public WifiSsid[] newArray(int size) {
235                 return new WifiSsid[size];
236             }
237         };
238 }
239