java.net.NetworkInterface Maven / Gradle / Ivy
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/*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You 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 java.net;
import java.io.BufferedReader;
import java.io.File;
import java.io.FileDescriptor;
import java.io.FileReader;
import java.io.IOException;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collections;
import java.util.Enumeration;
import java.util.LinkedList;
import java.util.List;
import java.util.Map;
import libcore.io.ErrnoException;
import libcore.io.IoUtils;
import libcore.io.Libcore;
import static libcore.io.OsConstants.*;
/**
* This class is used to represent a network interface of the local device. An
* interface is defined by its address and a platform dependent name. The class
* provides methods to get all information about the available interfaces of the
* system or to identify the local interface of a joined multicast group.
*/
public final class NetworkInterface extends Object {
private final String name;
private final int interfaceIndex;
private final List interfaceAddresses;
private final List addresses;
private final List children = new LinkedList();
private NetworkInterface parent = null;
private NetworkInterface(String name, int interfaceIndex,
List addresses, List interfaceAddresses) {
this.name = name;
this.interfaceIndex = interfaceIndex;
this.addresses = addresses;
this.interfaceAddresses = interfaceAddresses;
}
static NetworkInterface forUnboundMulticastSocket() {
// This is what the RI returns for a MulticastSocket that hasn't been constrained
// to a specific interface.
return new NetworkInterface(null, -1,
Arrays.asList(Inet6Address.ANY), Collections.emptyList());
}
/**
* Returns the index for the network interface, or -1 if unknown.
*
* @hide 1.7
*/
public int getIndex() {
return interfaceIndex;
}
/**
* Returns the name of this network interface (such as "eth0" or "lo").
*/
public String getName() {
return name;
}
/**
* Returns an enumeration of the addresses bound to this network interface.
*/
public Enumeration getInetAddresses() {
return Collections.enumeration(addresses);
}
/**
* Returns a human-readable name for this network interface. On Android, this is the same
* string as returned by {@link #getName}.
*/
public String getDisplayName() {
return name;
}
/**
* Returns the {@code NetworkInterface} corresponding to the named network interface, or null
* if no interface has this name.
*
* @throws SocketException if an error occurs.
* @throws NullPointerException if {@code interfaceName == null}.
*/
public static NetworkInterface getByName(String interfaceName) throws SocketException {
if (interfaceName == null) {
throw new NullPointerException("interfaceName == null");
}
if (!isValidInterfaceName(interfaceName)) {
return null;
}
int interfaceIndex = readIntFile("/sys/class/net/" + interfaceName + "/ifindex");
List addresses = new ArrayList();
List interfaceAddresses = new ArrayList();
collectIpv6Addresses(interfaceName, interfaceIndex, addresses, interfaceAddresses);
collectIpv4Address(interfaceName, addresses, interfaceAddresses);
return new NetworkInterface(interfaceName, interfaceIndex, addresses, interfaceAddresses);
}
private static void collectIpv6Addresses(String interfaceName, int interfaceIndex,
List addresses, List interfaceAddresses) throws SocketException {
// Format of /proc/net/if_inet6 (all numeric fields are implicit hex).
// 1. IPv6 address
// 2. interface index
// 3. prefix length
// 4. scope
// 5. flags
// 6. interface name
// "00000000000000000000000000000001 01 80 10 80 lo"
BufferedReader in = null;
try {
in = new BufferedReader(new FileReader("/proc/net/if_inet6"));
String suffix = " " + interfaceName;
String line;
while ((line = in.readLine()) != null) {
if (!line.endsWith(suffix)) {
continue;
}
byte[] addressBytes = new byte[16];
for (int i = 0; i < addressBytes.length; ++i) {
addressBytes[i] = (byte) Integer.parseInt(line.substring(2*i, 2*i + 2), 16);
}
short prefixLength = Short.parseShort(line.substring(36, 38), 16);
Inet6Address inet6Address = new Inet6Address(addressBytes, null, interfaceIndex);
addresses.add(inet6Address);
interfaceAddresses.add(new InterfaceAddress(inet6Address, prefixLength));
}
} catch (Exception ex) {
throw rethrowAsSocketException(ex);
} finally {
IoUtils.closeQuietly(in);
}
}
private static void collectIpv4Address(String interfaceName, List addresses,
List interfaceAddresses) throws SocketException {
FileDescriptor fd = null;
try {
fd = Libcore.os.socket(AF_INET, SOCK_DGRAM, 0);
InetAddress address = Libcore.os.ioctlInetAddress(fd, SIOCGIFADDR, interfaceName);
InetAddress broadcast = Libcore.os.ioctlInetAddress(fd, SIOCGIFBRDADDR, interfaceName);
InetAddress netmask = Libcore.os.ioctlInetAddress(fd, SIOCGIFNETMASK, interfaceName);
if (broadcast.equals(Inet4Address.ANY)) {
broadcast = null;
}
addresses.add(address);
interfaceAddresses.add(new InterfaceAddress((Inet4Address) address,
(Inet4Address) broadcast, (Inet4Address) netmask));
} catch (ErrnoException errnoException) {
if (errnoException.errno != EADDRNOTAVAIL) {
// EADDRNOTAVAIL just means no IPv4 address for this interface.
// Anything else is a real error.
throw rethrowAsSocketException(errnoException);
}
} catch (Exception ex) {
throw rethrowAsSocketException(ex);
} finally {
IoUtils.closeQuietly(fd);
}
}
@FindBugsSuppressWarnings("DMI_HARDCODED_ABSOLUTE_FILENAME")
private static boolean isValidInterfaceName(String interfaceName) {
// Don't just stat because a crafty user might have / or .. in the supposed interface name.
for (String validName : new File("/sys/class/net").list()) {
if (interfaceName.equals(validName)) {
return true;
}
}
return false;
}
private static int readIntFile(String path) throws SocketException {
try {
String s = IoUtils.readFileAsString(path).trim();
if (s.startsWith("0x")) {
return Integer.parseInt(s.substring(2), 16);
} else {
return Integer.parseInt(s);
}
} catch (Exception ex) {
throw rethrowAsSocketException(ex);
}
}
private static SocketException rethrowAsSocketException(Exception ex) throws SocketException {
SocketException result = new SocketException();
result.initCause(ex);
throw result;
}
/**
* Returns the {@code NetworkInterface} corresponding to the given address, or null if no
* interface has this address.
*
* @throws SocketException if an error occurs.
* @throws NullPointerException if {@code address == null}.
*/
public static NetworkInterface getByInetAddress(InetAddress address) throws SocketException {
if (address == null) {
throw new NullPointerException("address == null");
}
for (NetworkInterface networkInterface : getNetworkInterfacesList()) {
if (networkInterface.addresses.contains(address)) {
return networkInterface;
}
}
return null;
}
/**
* Returns the NetworkInterface corresponding to the given interface index, or null if no
* interface has this index.
*
* @throws SocketException if an error occurs.
* @hide 1.7
*/
public static NetworkInterface getByIndex(int index) throws SocketException {
String name = Libcore.os.if_indextoname(index);
if (name == null) {
return null;
}
return NetworkInterface.getByName(name);
}
/**
* Gets a list of all network interfaces available on the local system or
* {@code null} if no interface is available.
*
* @return the list of {@code NetworkInterface} instances representing the
* available interfaces.
* @throws SocketException
* if an error occurs while getting the network interface
* information.
*/
public static Enumeration getNetworkInterfaces() throws SocketException {
return Collections.enumeration(getNetworkInterfacesList());
}
@FindBugsSuppressWarnings("DMI_HARDCODED_ABSOLUTE_FILENAME")
private static List getNetworkInterfacesList() throws SocketException {
String[] interfaceNames = new File("/sys/class/net").list();
NetworkInterface[] interfaces = new NetworkInterface[interfaceNames.length];
boolean[] done = new boolean[interfaces.length];
for (int i = 0; i < interfaceNames.length; ++i) {
interfaces[i] = NetworkInterface.getByName(interfaceNames[i]);
// http://b/5833739: getByName can return null if the interface went away between our
// readdir(2) and our stat(2), so mark interfaces that disappeared as 'done'.
if (interfaces[i] == null) {
done[i] = true;
}
}
List result = new ArrayList();
for (int counter = 0; counter < interfaces.length; counter++) {
// If this interface has been dealt with already, continue.
if (done[counter]) {
continue;
}
int counter2 = counter;
// Checks whether the following interfaces are children.
for (; counter2 < interfaces.length; counter2++) {
if (done[counter2]) {
continue;
}
if (interfaces[counter2].name.startsWith(interfaces[counter].name + ":")) {
interfaces[counter].children.add(interfaces[counter2]);
interfaces[counter2].parent = interfaces[counter];
interfaces[counter].addresses.addAll(interfaces[counter2].addresses);
done[counter2] = true;
}
}
result.add(interfaces[counter]);
done[counter] = true;
}
return result;
}
/**
* Compares the specified object to this {@code NetworkInterface} and
* returns whether they are equal or not. The object must be an instance of
* {@code NetworkInterface} with the same name, display name, and list
* of interface addresses.
*
* @param obj
* the object to compare with this instance.
* @return {@code true} if the specified object is equal to this {@code
* NetworkInterface}, {@code false} otherwise.
* @see #hashCode()
*/
@Override
public boolean equals(Object obj) {
if (obj == this) {
return true;
}
if (!(obj instanceof NetworkInterface)) {
return false;
}
NetworkInterface rhs = (NetworkInterface) obj;
// TODO: should the order of the addresses matter (we use List.equals)?
return interfaceIndex == rhs.interfaceIndex &&
name.equals(rhs.name) &&
addresses.equals(rhs.addresses);
}
/**
* Returns the hash code for this {@code NetworkInterface}. Since the
* name should be unique for each network interface the hash code is
* generated using the name.
*/
@Override public int hashCode() {
return name.hashCode();
}
/**
* Returns a string containing details of this network interface.
* The exact format is deliberately unspecified. Callers that require a specific
* format should build a string themselves, using this class' accessor methods.
*/
@Override public String toString() {
StringBuilder sb = new StringBuilder(25);
sb.append("[");
sb.append(name);
sb.append("][");
sb.append(interfaceIndex);
sb.append("]");
for (InetAddress address : addresses) {
sb.append("[");
sb.append(address.toString());
sb.append("]");
}
return sb.toString();
}
/**
* Returns a List of the InterfaceAddresses for this network interface.
* @since 1.6
*/
public List getInterfaceAddresses() {
return Collections.unmodifiableList(interfaceAddresses);
}
/**
* Returns an enumeration of all the sub-interfaces of this network interface.
* Sub-interfaces are also known as virtual interfaces.
*
* For example, {@code eth0:1} would be a sub-interface of {@code eth0}.
*
* @return an Enumeration of all the sub-interfaces of this network interface
* @since 1.6
*/
public Enumeration getSubInterfaces() {
return Collections.enumeration(children);
}
/**
* Returns the parent NetworkInterface of this interface if this is a
* sub-interface, or null if it's a physical (non virtual) interface.
*
* @return the NetworkInterface this interface is attached to.
* @since 1.6
*/
public NetworkInterface getParent() {
return parent;
}
/**
* Returns true if this network interface is up.
*
* @return true if the interface is up.
* @throws SocketException if an I/O error occurs.
* @since 1.6
*/
public boolean isUp() throws SocketException {
return hasFlag(IFF_UP);
}
/**
* Returns true if this network interface is a loopback interface.
*
* @return true if the interface is a loopback interface.
* @throws SocketException if an I/O error occurs.
* @since 1.6
*/
public boolean isLoopback() throws SocketException {
return hasFlag(IFF_LOOPBACK);
}
/**
* Returns true if this network interface is a point-to-point interface.
* (For example, a PPP connection using a modem.)
*
* @return true if the interface is point-to-point.
* @throws SocketException if an I/O error occurs.
* @since 1.6
*/
public boolean isPointToPoint() throws SocketException {
return hasFlag(IFF_POINTOPOINT);
}
/**
* Returns true if this network interface supports multicast.
*
* @throws SocketException if an I/O error occurs.
* @since 1.6
*/
public boolean supportsMulticast() throws SocketException {
return hasFlag(IFF_MULTICAST);
}
private boolean hasFlag(int mask) throws SocketException {
int flags = readIntFile("/sys/class/net/" + name + "/flags");
return (flags & mask) != 0;
}
/**
* Returns the hardware address of the interface, if it has one, or null otherwise.
*
* @throws SocketException if an I/O error occurs.
* @since 1.6
*/
public byte[] getHardwareAddress() throws SocketException {
try {
// Parse colon-separated bytes with a trailing newline: "aa:bb:cc:dd:ee:ff\n".
String s = IoUtils.readFileAsString("/sys/class/net/" + name + "/address");
byte[] result = new byte[s.length()/3];
for (int i = 0; i < result.length; ++i) {
result[i] = (byte) Integer.parseInt(s.substring(3*i, 3*i + 2), 16);
}
// We only want to return non-zero hardware addresses.
for (int i = 0; i < result.length; ++i) {
if (result[i] != 0) {
return result;
}
}
return null;
} catch (Exception ex) {
throw rethrowAsSocketException(ex);
}
}
/**
* Returns the Maximum Transmission Unit (MTU) of this interface.
*
* @return the value of the MTU for the interface.
* @throws SocketException if an I/O error occurs.
* @since 1.6
*/
public int getMTU() throws SocketException {
return readIntFile("/sys/class/net/" + name + "/mtu");
}
/**
* Returns true if this interface is a virtual interface (also called
* a sub-interface). Virtual interfaces are, on some systems, interfaces
* created as a child of a physical interface and given different settings
* (like address or MTU). Usually the name of the interface will the name of
* the parent followed by a colon (:) and a number identifying the child,
* since there can be several virtual interfaces attached to a single
* physical interface.
*
* @return true if this interface is a virtual interface.
* @since 1.6
*/
public boolean isVirtual() {
return parent != null;
}
}