467 lines
19 KiB
Kotlin
467 lines
19 KiB
Kotlin
/*
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* Copyright 2023 dorkbox, llc
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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package dorkbox.netUtil.dnsUtils
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import com.sun.jna.Memory
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import com.sun.jna.Pointer
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import com.sun.jna.platform.win32.WinError
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import dorkbox.netUtil.Common
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import dorkbox.netUtil.Dns
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import dorkbox.netUtil.IP
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import dorkbox.netUtil.jna.windows.IPHlpAPI
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import dorkbox.netUtil.jna.windows.structs.IP_ADAPTER_ADDRESSES_LH
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import dorkbox.netUtil.jna.windows.structs.IP_ADAPTER_DNS_SERVER_ADDRESS_XP
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import java.io.BufferedReader
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import java.io.FileReader
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import java.io.IOException
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import java.io.InputStream
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import java.io.InputStreamReader
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import java.net.Inet4Address
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import java.net.InetAddress
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import java.net.InetSocketAddress
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import java.net.URI
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import java.net.URISyntaxException
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import java.net.UnknownHostException
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import java.nio.file.Files
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import java.nio.file.Paths
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import java.util.*
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import javax.naming.Context
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import javax.naming.NamingException
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import javax.naming.directory.DirContext
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import javax.naming.directory.InitialDirContext
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/**
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*
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*/
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object ResolveConf {
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private const val NAMESERVER_ROW_LABEL = "nameserver"
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private const val DOMAIN_ROW_LABEL = "domain"
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private const val PORT_ROW_LABEL = "port"
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// largely from:
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// https://github.com/dnsjava/dnsjava/blob/fb4889ee7a73f391f43bf6dc78b019d87ae15f15/src/main/java/org/xbill/DNS/config/BaseResolverConfigProvider.java#L22
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internal fun getUnsortedNameServers(): Map<String, List<InetSocketAddress>> {
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val nameServerDomains = mutableMapOf<String, List<InetSocketAddress>>()
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// Using jndi-dns to obtain the default name servers.
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//
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// See:
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// - http://docs.oracle.com/javase/8/docs/technotes/guides/jndi/jndi-dns.html
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// - http://mail.openjdk.java.net/pipermail/net-dev/2017-March/010695.html
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// Using jndi-dns to obtain the default name servers.
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//
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// See:
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// - http://docs.oracle.com/javase/8/docs/technotes/guides/jndi/jndi-dns.html
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// - http://mail.openjdk.java.net/pipermail/net-dev/2017-March/010695.html
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val env = Hashtable<String, String>()
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env[Context.INITIAL_CONTEXT_FACTORY] = "com.sun.jndi.dns.DnsContextFactory"
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env["java.naming.provider.url"] = "dns://"
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try {
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val ctx: DirContext = InitialDirContext(env)
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val dnsUrls = ctx.environment["java.naming.provider.url"] as String?
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if (dnsUrls != null) {
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val servers = dnsUrls.split(" ".toRegex()).toTypedArray()
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for (server in servers) {
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try {
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putIfAbsent(nameServerDomains, Dns.DEFAULT_SEARCH_DOMAIN, Common.socketAddress(URI(server).host, 53))
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} catch (e: URISyntaxException) {
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Common.logger.debug("Skipping a malformed nameserver URI: {}", server, e)
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}
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}
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}
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} catch (ignore: NamingException) {
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// Will also try JNA/etc if this fails.
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}
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if (Common.OS_WINDOWS) {
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// have to use JNA to access the WINDOWS resolver info
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// modified from: https://github.com/dnsjava/dnsjava/blob/master/src/main/java/org/xbill/DNS/config/WindowsResolverConfigProvider.java
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// The recommended method of calling the GetAdaptersAddresses function is to pre-allocate a 15KB working buffer
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var buffer = Memory(15 * 1024)
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val size: com.sun.jna.ptr.IntByReference = com.sun.jna.ptr.IntByReference(0)
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val flags: Int = IPHlpAPI.GAA_FLAG_SKIP_UNICAST or
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IPHlpAPI.GAA_FLAG_SKIP_ANYCAST or
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IPHlpAPI.GAA_FLAG_SKIP_MULTICAST or
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IPHlpAPI.GAA_FLAG_SKIP_FRIENDLY_NAME
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var error: Int = IPHlpAPI.GetAdaptersAddresses(
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IPHlpAPI.AF_UNSPEC,
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flags,
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Pointer.NULL,
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buffer,
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size
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)
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if (error == WinError.ERROR_BUFFER_OVERFLOW) {
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buffer = Memory(size.value.toLong())
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error = IPHlpAPI.GetAdaptersAddresses(
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IPHlpAPI.AF_UNSPEC,
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flags,
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Pointer.NULL,
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buffer,
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size
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)
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}
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if (error == WinError.ERROR_SUCCESS) {
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var result: IP_ADAPTER_ADDRESSES_LH? = IP_ADAPTER_ADDRESSES_LH(buffer)
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while (result != null) {
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// only interfaces with IfOperStatusUp
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if (result.OperStatus == 1) {
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var dns: IP_ADAPTER_DNS_SERVER_ADDRESS_XP? = result.FirstDnsServerAddress
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while (dns != null) {
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var address: InetAddress?
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try {
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address = dns.Address?.toAddress()
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if (address is Inet4Address || !address!!.isSiteLocalAddress) {
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putIfAbsent(nameServerDomains, Dns.DEFAULT_SEARCH_DOMAIN, Common.socketAddress(address, 53))
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} else {
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Common.logger.trace(
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"Skipped site-local IPv6 server address {} on adapter index {}",
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address,
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result.IfIndex
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)
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}
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} catch (e: UnknownHostException) {
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Common.logger.warn("Invalid nameserver address on adapter index {}", result.IfIndex, e)
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}
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dns = dns.Next
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}
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}
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result = result.Next
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}
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}
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} else {
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// try resolve.conf
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// first try the default unix config path
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var tryParse = tryParseResolvConfNameservers("/etc/resolv.conf")
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if (!tryParse.first) {
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// then fallback to netware
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tryParse = tryParseResolvConfNameservers("sys:/etc/resolv.cfg")
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}
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if (tryParse.first) {
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// we can have DIFFERENT name servers for DIFFERENT domains!
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tryParse.second
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}
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}
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// if we STILL don't have anything, add global nameservers to the default search domain
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if (nameServerDomains[Dns.DEFAULT_SEARCH_DOMAIN] == null) {
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putIfAbsent(nameServerDomains, Dns.DEFAULT_SEARCH_DOMAIN, Common.socketAddress("1.1.1.1", 53)) // cloudflare
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putIfAbsent(nameServerDomains, Dns.DEFAULT_SEARCH_DOMAIN, Common.socketAddress("1.1.1.1", 53)) // google
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}
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return nameServerDomains
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}
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private fun tryParseResolvConfNameservers(path: String): Pair<Boolean, Map<String, List<InetSocketAddress>>> {
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val p = Paths.get(path)
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if (Files.exists(p)) {
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try {
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FileReader(path).use { fr ->
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BufferedReader(fr).use { br ->
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var nameServers = mutableListOf<InetSocketAddress>()
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val nameServerDomains = mutableMapOf<String, List<InetSocketAddress>>()
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@Suppress("UNUSED_VARIABLE")
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var port = 53 // this is really used, it's just that the kotlin compiler doesn't notice
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var domainName = Dns.DEFAULT_SEARCH_DOMAIN
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var line0: String?
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loop@ while (br.readLine().also { line0 = it?.trim() } != null) {
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val line = line0!!
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if (line.isEmpty()) {
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continue@loop
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}
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val c = line[0]
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if (c == '#' || c == ';') {
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continue
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}
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when {
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line.startsWith(NAMESERVER_ROW_LABEL) -> {
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var i = indexOfNonWhiteSpace(line, NAMESERVER_ROW_LABEL.length)
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require(i >= 0) {
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"error parsing label $NAMESERVER_ROW_LABEL in file $path. value: $line"
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}
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var maybeIP = line.substring(i)
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// There MIGHT be a port appended onto the IP address so we attempt to extract it.
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if (!IP.isValid(maybeIP)) {
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i = maybeIP.lastIndexOf('.')
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require(i + 1 >= maybeIP.length) {
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"error parsing label ${NAMESERVER_ROW_LABEL} in file $path. invalid IP value: $line"
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}
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port = maybeIP.substring(i + 1).toInt()
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maybeIP = maybeIP.substring(0, i)
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}
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nameServers.add(Common.socketAddress(maybeIP, port))
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}
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line.startsWith(DOMAIN_ROW_LABEL) -> {
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// nameservers can be SPECIFIC to a search domain
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val i = indexOfNonWhiteSpace(line, DOMAIN_ROW_LABEL.length)
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require(i >= 0) {
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"error parsing label $DOMAIN_ROW_LABEL in file $path value: $line"
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}
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// we have a NEW domain! add the PREVIOUS nameServers and start again.
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putIfAbsent(nameServerDomains, domainName, nameServers)
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nameServers = mutableListOf()
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domainName = line.substring(i)
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}
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line.startsWith(PORT_ROW_LABEL) -> {
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val i = indexOfNonWhiteSpace(line, PORT_ROW_LABEL.length)
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require(i >= 0) {
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"error parsing label $PORT_ROW_LABEL in file $path value: $line"
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}
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@Suppress("UNUSED_VALUE")
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port = line.substring(i).toInt()
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}
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}
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// end loop
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}
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// when done parsing the file, ALWAYS add the nameServer domains (since they have not been added yet)
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putIfAbsent(nameServerDomains, domainName, nameServers)
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return Pair(true, nameServerDomains)
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}
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}
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} catch (e: IOException) {
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Common.logger.error("Error parsing $path", e)
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}
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}
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return Pair(false, mutableMapOf())
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}
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/**
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* Find the index of the first non-white space character in `s` starting at `offset`.
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*
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* @param seq The string to search.
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* @param offset The offset to start searching at.
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* @return the index of the first non-white space character or <`-1` if none was found.
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*/
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private fun indexOfNonWhiteSpace(seq: CharSequence, offset: Int): Int {
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var o = offset
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while (o < seq.length) {
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if (!Character.isWhitespace(seq[o])) {
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return o
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}
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++o
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}
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return -1
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}
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private fun putIfAbsent(
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nameServerDomains: MutableMap<String, List<InetSocketAddress>>,
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domainName: String,
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nameServer: InetSocketAddress
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) {
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var list = nameServerDomains[domainName]
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if (list == null) {
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list = mutableListOf()
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nameServerDomains[domainName] = list
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}
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(list as MutableList)
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if (!list.contains(nameServer)) {
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list.add(nameServer)
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}
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}
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private fun putIfAbsent(
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nameServerDomains: MutableMap<String, List<InetSocketAddress>>,
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domainName: String,
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nameServers: List<InetSocketAddress>
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) {
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var list = nameServerDomains[domainName]
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if (list == null) {
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list = mutableListOf()
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nameServerDomains[domainName] = list
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}
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(list as MutableList)
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nameServers.forEach {
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if (!list.contains(it)) {
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list.add(it)
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}
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}
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}
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internal fun tryParseResolvConfNDots(path: String): Pair<Boolean, Int> {
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val p = Paths.get(path)
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if (Files.exists(p)) {
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try {
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Files.newInputStream(p).use { `in` ->
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return Pair(true, getNdots(`in`))
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}
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} catch (e: IOException) {
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// ignore
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}
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}
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return Pair(false, 1)
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}
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// @kotlin.jvm.Throws(IOException::class)
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// private fun parseResolvConf(`in`: InputStream) {
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// InputStreamReader(`in`).use { isr ->
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// BufferedReader(isr).use { br ->
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//
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// var line: String?
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// loop@ while (br.readLine().also { line = it } != null) {
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// val st = StringTokenizer(line)
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// if (!st.hasMoreTokens()) {
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// continue
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// }
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// when (st.nextToken()) {
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// "domain" -> {
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// // man resolv.conf:
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// // The domain and search keywords are mutually exclusive. If more than one instance of
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// // these keywords is present, the last instance wins.
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// searchlist.clear()
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// if (!st.hasMoreTokens()) {
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// continue@loop
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// }
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// addSearchPath(st.nextToken())
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// }
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// "search" -> {
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// // man resolv.conf:
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// // The domain and search keywords are mutually exclusive. If more than one instance of
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// // these keywords is present, the last instance wins.
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// searchlist.clear()
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// while (st.hasMoreTokens()) {
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// addSearchPath(st.nextToken())
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// }
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// }
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// }
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// }
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// }
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// }
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//
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// // man resolv.conf:
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// // The search keyword of a system's resolv.conf file can be overridden on a per-process basis by
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// // setting the environment variable LOCALDOMAIN to a space-separated list of search domains.
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// val localdomain = System.getenv("LOCALDOMAIN")
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// if (localdomain != null && !localdomain.isEmpty()) {
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// searchlist.clear()
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// parseSearchPathList(localdomain, " ")
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// }
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// }
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private fun getNdots(`in`: InputStream): Int {
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var ndots = 1
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InputStreamReader(`in`).use { isr ->
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BufferedReader(isr).use { br ->
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var line: String?
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loop@ while (br.readLine().also { line = it } != null) {
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val st = StringTokenizer(line)
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if (!st.hasMoreTokens()) {
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continue
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}
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when (st.nextToken()) {
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"domain" -> {
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// man resolv.conf:
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// The domain and search keywords are mutually exclusive. If more than one instance of
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// these keywords is present, the last instance wins.
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if (!st.hasMoreTokens()) {
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continue@loop
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}
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}
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"search" -> {
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// man resolv.conf:
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// The domain and search keywords are mutually exclusive. If more than one instance of
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// these keywords is present, the last instance wins.
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while (st.hasMoreTokens()) {
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val token = st.nextToken()
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if (token.startsWith("ndots:")) {
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ndots = parseNdots(token.substring(6))
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}
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}
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}
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"options" -> while (st.hasMoreTokens()) {
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val token = st.nextToken()
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if (token.startsWith("ndots:")) {
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ndots = parseNdots(token.substring(6))
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}
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}
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}
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}
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}
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}
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// man resolv.conf:
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// The options keyword of a system's resolv.conf file can be amended on a per-process basis by
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// setting the environment variable RES_OPTIONS to a space-separated list of resolver options as
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// explained above under options.
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val resOptions = System.getenv("RES_OPTIONS")
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if (resOptions != null && !resOptions.isEmpty()) {
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val st = StringTokenizer(resOptions, " ")
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while (st.hasMoreTokens()) {
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val token = st.nextToken()
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if (token.startsWith("ndots:")) {
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ndots = parseNdots(token.substring(6))
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}
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}
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}
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return ndots
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}
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private fun parseNdots(token: String): Int {
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if (token.isNotEmpty()) {
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try {
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var ndots = token.toInt()
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if (ndots >= 0) {
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if (ndots > 15) {
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// man resolv.conf:
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// The value for this option is silently capped to 15
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ndots = 15
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}
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return ndots
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}
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} catch (e: NumberFormatException) {
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// ignore
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}
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}
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return 1
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}
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}
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