/*
* Copyright (C) 2012 The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package android.net.wifi.p2p.nsd;
import android.net.nsd.DnsSdTxtRecord;
import android.text.TextUtils;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Locale;
import java.util.Map;
/**
* A class for storing Bonjour service information that is advertised
* over a Wi-Fi peer-to-peer setup.
*
* {@see android.net.wifi.p2p.WifiP2pManager#addLocalService}
* {@see android.net.wifi.p2p.WifiP2pManager#removeLocalService}
* {@see WifiP2pServiceInfo}
* {@see WifiP2pUpnpServiceInfo}
*/
public class WifiP2pDnsSdServiceInfo extends WifiP2pServiceInfo {
/**
* Bonjour version 1.
* @hide
*/
public static final int VERSION_1 = 0x01;
/**
* Pointer record.
* @hide
*/
public static final int DNS_TYPE_PTR = 12;
/**
* Text record.
* @hide
*/
public static final int DNS_TYPE_TXT = 16;
/**
* virtual memory packet.
* see E.3 of the Wi-Fi Direct technical specification for the detail.<br>
* Key: domain name Value: pointer address.<br>
*/
private final static Map<String, String> sVmPacket;
static {
sVmPacket = new HashMap<String, String>();
sVmPacket.put("_tcp.local.", "c00c");
sVmPacket.put("local.", "c011");
sVmPacket.put("_udp.local.", "c01c");
}
/**
* This constructor is only used in newInstance().
*
* @param queryList
*/
private WifiP2pDnsSdServiceInfo(List<String> queryList) {
super(queryList);
}
/**
* Create a Bonjour service information object.
*
* @param instanceName instance name.<br>
* e.g) "MyPrinter"
* @param serviceType service type.<br>
* e.g) "_ipp._tcp"
* @param txtMap TXT record with key/value pair in a map confirming to format defined at
* http://files.dns-sd.org/draft-cheshire-dnsext-dns-sd.txt
* @return Bonjour service information object
*/
public static WifiP2pDnsSdServiceInfo newInstance(String instanceName,
String serviceType, Map<String, String> txtMap) {
if (TextUtils.isEmpty(instanceName) || TextUtils.isEmpty(serviceType)) {
throw new IllegalArgumentException(
"instance name or service type cannot be empty");
}
DnsSdTxtRecord txtRecord = new DnsSdTxtRecord();
if (txtMap != null) {
for (String key : txtMap.keySet()) {
txtRecord.set(key, txtMap.get(key));
}
}
ArrayList<String> queries = new ArrayList<String>();
queries.add(createPtrServiceQuery(instanceName, serviceType));
queries.add(createTxtServiceQuery(instanceName, serviceType, txtRecord));
return new WifiP2pDnsSdServiceInfo(queries);
}
/**
* Create wpa_supplicant service query for PTR record.
*
* @param instanceName instance name.<br>
* e.g) "MyPrinter"
* @param serviceType service type.<br>
* e.g) "_ipp._tcp"
* @return wpa_supplicant service query.
*/
private static String createPtrServiceQuery(String instanceName,
String serviceType) {
StringBuffer sb = new StringBuffer();
sb.append("bonjour ");
sb.append(createRequest(serviceType + ".local.", DNS_TYPE_PTR, VERSION_1));
sb.append(" ");
byte[] data = instanceName.getBytes();
sb.append(String.format(Locale.US, "%02x", data.length));
sb.append(WifiP2pServiceInfo.bin2HexStr(data));
// This is the start point of this response.
// Therefore, it indicates the request domain name.
sb.append("c027");
return sb.toString();
}
/**
* Create wpa_supplicant service query for TXT record.
*
* @param instanceName instance name.<br>
* e.g) "MyPrinter"
* @param serviceType service type.<br>
* e.g) "_ipp._tcp"
* @param txtRecord TXT record.<br>
* @return wpa_supplicant service query.
*/
private static String createTxtServiceQuery(String instanceName,
String serviceType,
DnsSdTxtRecord txtRecord) {
StringBuffer sb = new StringBuffer();
sb.append("bonjour ");
sb.append(createRequest((instanceName + "." + serviceType + ".local."),
DNS_TYPE_TXT, VERSION_1));
sb.append(" ");
byte[] rawData = txtRecord.getRawData();
if (rawData.length == 0) {
sb.append("00");
} else {
sb.append(bin2HexStr(rawData));
}
return sb.toString();
}
/**
* Create bonjour service discovery request.
*
* @param dnsName dns name
* @param dnsType dns type
* @param version version number
* @hide
*/
static String createRequest(String dnsName, int dnsType, int version) {
StringBuffer sb = new StringBuffer();
/*
* The request format is as follows.
* ________________________________________________
* | Encoded and Compressed dns name (variable) |
* ________________________________________________
* | Type (2) | Version (1) |
*/
if (dnsType == WifiP2pDnsSdServiceInfo.DNS_TYPE_TXT) {
dnsName = dnsName.toLowerCase(Locale.ROOT); // TODO: is this right?
}
sb.append(compressDnsName(dnsName));
sb.append(String.format(Locale.US, "%04x", dnsType));
sb.append(String.format(Locale.US, "%02x", version));
return sb.toString();
}
/**
* Compress DNS data.
*
* see E.3 of the Wi-Fi Direct technical specification for the detail.
*
* @param dnsName dns name
* @return compressed dns name
*/
private static String compressDnsName(String dnsName) {
StringBuffer sb = new StringBuffer();
// The domain name is replaced with a pointer to a prior
// occurrence of the same name in virtual memory packet.
while (true) {
String data = sVmPacket.get(dnsName);
if (data != null) {
sb.append(data);
break;
}
int i = dnsName.indexOf('.');
if (i == -1) {
if (dnsName.length() > 0) {
sb.append(String.format(Locale.US, "%02x", dnsName.length()));
sb.append(WifiP2pServiceInfo.bin2HexStr(dnsName.getBytes()));
}
// for a sequence of labels ending in a zero octet
sb.append("00");
break;
}
String name = dnsName.substring(0, i);
dnsName = dnsName.substring(i + 1);
sb.append(String.format(Locale.US, "%02x", name.length()));
sb.append(WifiP2pServiceInfo.bin2HexStr(name.getBytes()));
}
return sb.toString();
}
}
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