Added ability to get LAN address
Robinson
parent
1cc7ac128b
commit
2164890bd0
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@ -1,12 +1,7 @@
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package dorkbox.netUtil
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import dorkbox.netUtil.Common.logger
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import java.net.Inet4Address
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import java.net.Inet6Address
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import java.net.InetAddress
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import java.net.InetSocketAddress
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import java.net.NetworkInterface
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import java.net.SocketException
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import java.net.*
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/**
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* A class that holds a number of network-related constants, also from:
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@ -131,6 +126,117 @@ object IP {
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LOCALHOST = loopbackAddr!!
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}
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/**
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* The LAN address of the machine, to the best of our ability
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*/
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fun lanAddress(): InetAddress {
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/**
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* Returns an `InetAddress` object encapsulating what is most likely the machine's LAN IP address.
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*
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*
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* This method is intended for use as a replacement of JDK method `InetAddress.getLocalHost`, because
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* that method is ambiguous on Linux systems. Linux systems enumerate the loopback network interface the same
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* way as regular LAN network interfaces, but the JDK `InetAddress.getLocalHost` method does not
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* specify the algorithm used to select the address returned under such circumstances, and will often return the
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* loopback address, which is not valid for network communication. Details
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* [here](http://bugs.sun.com/bugdatabase/view_bug.do?bug_id=4665037).
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*
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*
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* This method will scan all IP addresses on all network interfaces on the host machine to determine the IP address
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* most likely to be the machine's LAN address. If the machine has multiple IP addresses, this method will prefer
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* a site-local IP address (e.g. 192.168.x.x or 10.10.x.x, usually IPv4) if the machine has one (and will return the
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* first site-local address if the machine has more than one), but if the machine does not hold a site-local
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* address, this method will return simply the first non-loopback address found (IPv4 or IPv6).
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*
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*
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* If this method cannot find a non-loopback address using this selection algorithm, it will fall back to
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* calling and returning the result of JDK method `InetAddress.getLocalHost`.
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*
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*
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* @throws UnknownHostException If the LAN address of the machine cannot be found.
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*
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* From: https://issues.apache.org/jira/browse/JCS-40
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*/
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val likelyAddress = mutableListOf<InetAddress>()
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val candidates = mutableListOf<InetAddress>()
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try {
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// Iterate all NICs (network interface cards)...
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val ifaces = NetworkInterface.getNetworkInterfaces()
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while (ifaces.hasMoreElements()) {
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val iface = ifaces.nextElement()
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// Iterate all IP addresses assigned to each card...
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val inetAddrs = iface.inetAddresses
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while (inetAddrs.hasMoreElements()) {
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val inetAddr = inetAddrs.nextElement()
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if (!inetAddr.isLoopbackAddress) {
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if (inetAddr.isSiteLocalAddress) {
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// Found non-loopback site-local address. Return it immediately...
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likelyAddress.add(inetAddr)
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} else {
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// Found non-loopback address, but not necessarily site-local.
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// Store it as a candidate to be returned if site-local address is not subsequently found...
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candidates.add(inetAddr)
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}
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}
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}
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}
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} catch (e: Exception) {
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// ignored
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}
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if (likelyAddress.size == 1) {
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return likelyAddress.first()
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}
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// we have MORE than 1 likely address, but we DO NOT know which one is used for 0.0.0.0 traffic.
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// we **COULD** parse out the gateway information from the routes for each interface... but that is a huge amount of work.
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// it's MUCH easier to see if open a connection to 1.1.1.1 and get the interface this traffic was on, and use that interface IP address
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runCatching {
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Socket().use {
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it.connect(InetSocketAddress("1.1.1.1", 80))
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return it.localAddress
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}
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}.onFailure {
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Common.logger.error("Unable to determine outbound traffic local address. Using alternate logic instead.", it)
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}
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// there was an error doing this! (it's possible that outbound traffic is not allowed
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if (IPv6.isPreferred) {
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val ipv6 = likelyAddress.filterIsInstance<Inet6Address>()
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if (ipv6.isNotEmpty()) {
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return ipv6.first()
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}
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} else if (IPv4.isPreferred) {
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val ipv4 = likelyAddress.filterIsInstance<Inet4Address>()
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if (ipv4.isNotEmpty()) {
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return ipv4.first()
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}
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}
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// we STILL don't have something. Possibly that we have no likely addresses, but we
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// found some other non-loopback address.
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// The machine might have a non-site-local address assigned to its NIC (or it might be running
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// IPv6 which deprecates the "site-local" concept).
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// Return this non-loopback candidate address...
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if (IPv6.isPreferred) {
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val ipv6 = candidates.filterIsInstance<Inet6Address>()
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if (ipv6.isNotEmpty()) {
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return ipv6.first()
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}
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} else if (IPv4.isPreferred) {
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val ipv4 = candidates.filterIsInstance<Inet4Address>()
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if (ipv4.isNotEmpty()) {
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return ipv4.first()
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}
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}
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// At this point, we did not find a non-loopback address.
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// Fall back to returning whatever InetAddress.getLocalHost() returns...
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return InetAddress.getLocalHost()
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?: throw UnknownHostException("The JDK InetAddress.getLocalHost() method unexpectedly returned null.")
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}
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/**
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* Creates an byte[] based on an ipAddressString. No error handling is performed here.
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*/
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