LineageOS/android_packages_modules_Connectivity
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Parse and validate txt records.

Browse Source 
Bug: 27696905
Change-Id: I9affcf02a51c92a2be1c2bfc5efbd09065e100bc
This commit is contained in:
Philip P. Moltmann
2016-03-16 10:15:39 -07:00
parent 70afb70e73
commit bbb41dd3bd
2 changed files with 101 additions and 19 deletions
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98
core/java/android/net/nsd/NsdServiceInfo.java
View File

@@ -16,8 +16,11 @@
package android.net.nsd;
import android.annotation.NonNull;
import android.os.Parcelable;
import android.os.Parcel;
import android.text.TextUtils;
import android.util.Base64;
import android.util.Log;
import android.util.ArrayMap;
@@ -95,8 +98,99 @@ public final class NsdServiceInfo implements Parcelable {
mPort = p;
}
/**
* Unpack txt information from a base-64 encoded byte array.
*
* @param rawRecords The raw base64 encoded records string read from netd.
*
* @hide
*/
public void setTxtRecords(@NonNull String rawRecords) {
byte[] txtRecordsRawBytes = Base64.decode(rawRecords, Base64.DEFAULT);
// There can be multiple TXT records after each other. Each record has to following format:
//
// byte type required meaning
// ------------------- ------------------- -------- ----------------------------------
// 0 unsigned 8 bit yes size of record excluding this byte
// 1 - n ASCII but not '=' yes key
// n + 1 '=' optional separator of key and value
// n + 2 - record size uninterpreted bytes optional value
//
// Example legal records:
// [11, 'm', 'y', 'k', 'e', 'y', '=', 0x0, 0x4, 0x65, 0x7, 0xff]
// [17, 'm', 'y', 'K', 'e', 'y', 'W', 'i', 't', 'h', 'N', 'o', 'V', 'a', 'l', 'u', 'e', '=']
// [12, 'm', 'y', 'B', 'o', 'o', 'l', 'e', 'a', 'n', 'K', 'e', 'y']
//
// Example corrupted records
// [3, =, 1, 2] <- key is empty
// [3, 0, =, 2] <- key contains non-ASCII character. We handle this by replacing the
// invalid characters instead of skipping the record.
// [30, 'a', =, 2] <- length exceeds total left over bytes in the TXT records array, we
// handle this by reducing the length of the record as needed.
int pos = 0;
while (pos < txtRecordsRawBytes.length) {
// recordLen is an unsigned 8 bit value
int recordLen = txtRecordsRawBytes[pos] & 0xff;
pos += 1;
try {
if (recordLen == 0) {
throw new IllegalArgumentException("Zero sized txt record");
} else if (pos + recordLen > txtRecordsRawBytes.length) {
Log.w(TAG, "Corrupt record length (pos = " + pos + "): " + recordLen);
recordLen = txtRecordsRawBytes.length - pos;
}
// Decode key-value records
String key = null;
byte[] value = null;
int valueLen = 0;
for (int i = pos; i < pos + recordLen; i++) {
if (key == null) {
if (txtRecordsRawBytes[i] == '=') {
key = new String(txtRecordsRawBytes, pos, i - pos,
StandardCharsets.US_ASCII);
}
} else {
if (value == null) {
value = new byte[recordLen - key.length() - 1];
}
value[valueLen] = txtRecordsRawBytes[i];
valueLen++;
}
}
// If '=' was not found we have a boolean record
if (key == null) {
key = new String(txtRecordsRawBytes, pos, recordLen, StandardCharsets.US_ASCII);
}
if (TextUtils.isEmpty(key)) {
// Empty keys are not allowed (RFC6763 6.4)
throw new IllegalArgumentException("Invalid txt record (key is empty)");
}
if (getAttributes().containsKey(key)) {
// When we have a duplicate record, the later ones are ignored (RFC6763 6.4)
throw new IllegalArgumentException("Invalid txt record (duplicate key \"" + key + "\")");
}
setAttribute(key, value);
} catch (IllegalArgumentException e) {
Log.e(TAG, "While parsing txt records (pos = " + pos + "): " + e.getMessage());
}
pos += recordLen;
}
}
/** @hide */
public void setAttribute(String key, byte[] value) {
if (TextUtils.isEmpty(key)) {
throw new IllegalArgumentException("Key cannot be empty");
}
// Key must be printable US-ASCII, excluding =.
for (int i = 0; i < key.length(); ++i) {
char character = key.charAt(i);
@@ -177,10 +271,10 @@ public final class NsdServiceInfo implements Parcelable {
}
/** @hide */
public byte[] getTxtRecord() {
public @NonNull byte[] getTxtRecord() {
int txtRecordSize = getTxtRecordSize();
if (txtRecordSize == 0) {
return null;
return new byte[]{};
}
byte[] txtRecord = new byte[txtRecordSize];

22
services/core/java/com/android/server/NsdService.java
View File

@@ -30,16 +30,14 @@ import android.os.Message;
import android.os.Messenger;
import android.os.UserHandle;
import android.provider.Settings;
import android.util.Base64;
import android.util.Slog;
import android.util.SparseArray;
import java.io.FileDescriptor;
import java.io.PrintWriter;
import java.io.UnsupportedEncodingException;
import java.net.InetAddress;
import java.util.HashMap;
import java.util.Locale;
import java.util.Map;
import java.util.concurrent.CountDownLatch;
import com.android.internal.util.AsyncChannel;
@@ -492,6 +490,7 @@ public class NsdService extends INsdManager.Stub {
clientInfo.mResolvedService.setServiceName(name);
clientInfo.mResolvedService.setServiceType(type);
clientInfo.mResolvedService.setPort(Integer.parseInt(cooked[4]));
clientInfo.mResolvedService.setTxtRecords(cooked[6]);
stopResolveService(id);
removeRequestMap(clientId, id, clientInfo);
@@ -708,20 +707,9 @@ public class NsdService extends INsdManager.Stub {
if (DBG) Slog.d(TAG, "registerService: " + regId + " " + service);
try {
Command cmd = new Command("mdnssd", "register", regId, service.getServiceName(),
service.getServiceType(), service.getPort());
// Add TXT records as additional arguments.
Map<String, byte[]> txtRecords = service.getAttributes();
for (String key : txtRecords.keySet()) {
try {
// TODO: Send encoded TXT record as bytes once NDC/netd supports binary data.
byte[] recordValue = txtRecords.get(key);
cmd.appendArg(String.format(Locale.US, "%s=%s", key,
recordValue != null ? new String(recordValue, "UTF_8") : ""));
} catch (UnsupportedEncodingException e) {
Slog.e(TAG, "Failed to encode txtRecord " + e);
}
}
service.getServiceType(), service.getPort(),
Base64.encodeToString(service.getTxtRecord(), Base64.DEFAULT)
.replace("\n", ""));
mNativeConnector.execute(cmd);
} catch(NativeDaemonConnectorException e) {