Supports different search domains in addition to the default for resolv.conf parsing
Robinson
parent
fb99d1cd25
commit
6774c8c411
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@ -11,6 +11,8 @@ import java.io.*
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import java.net.*
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import java.nio.file.Files
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import java.nio.file.Paths
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import java.security.AccessController
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import java.security.PrivilegedAction
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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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@ -24,6 +26,11 @@ object Dns {
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*/
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const val version = "2.1"
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private const val DEFAULT_SEARCH_DOMAIN = ""
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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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/**
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* @throws IOException if the DNS resolve.conf file cannot be read
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*/
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@ -53,7 +60,6 @@ object Dns {
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}
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}
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/** Returns all located name servers, which may be empty. */
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val defaultNameServers: List<InetSocketAddress> by lazy {
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val nameServers = getUnsortedDefaultNameServers()
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@ -178,45 +184,109 @@ object Dns {
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tryParse = tryParseResolvConfNameservers("sys:/etc/resolv.cfg")
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}
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defaultNameServers.addAll(tryParse.second)
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if (tryParse.first) {
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// we can have DIFFERENT name servers for DIFFERENT domains!
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val defaultSearchDomainNameServers = tryParse.second[DEFAULT_SEARCH_DOMAIN]
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if (defaultSearchDomainNameServers != null) {
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defaultNameServers.addAll(defaultSearchDomainNameServers)
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}
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}
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}
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// if we STILL don't have anything, add global nameservers
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if (defaultNameServers.isEmpty()) {
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defaultNameServers.add(InetSocketAddress("1.1.1.1", 53)) // cloudflare
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defaultNameServers.add(InetSocketAddress("8.8.8.8", 53)) // google
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}
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return defaultNameServers
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}
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private fun tryParseResolvConfNameservers(path: String): Pair<Boolean, MutableList<InetSocketAddress>> {
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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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Files.newInputStream(p).use { `in` ->
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return Pair(true, parseResolvConfNameservers(`in`))
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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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var domainName = DEFAULT_SEARCH_DOMAIN
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var port = 53
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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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if (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 may be a port appended onto the IP address so we attempt to extract it.
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// There may be a port appended onto the IP address so we attempt to extract it.
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if (!IPv4.isValid(maybeIP) && !IPv6.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(socketAddress(maybeIP, port))
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} else if (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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if (nameServerDomains[domainName] == null) {
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nameServerDomains[domainName] = mutableListOf()
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}
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(nameServerDomains[domainName] as MutableList).addAll(nameServers)
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nameServers = mutableListOf()
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domainName = line.substring(i)
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} else if (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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port = line.substring(i).toInt()
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}
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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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if (nameServerDomains[domainName] == null) {
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nameServerDomains[domainName] = mutableListOf()
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}
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(nameServerDomains[domainName] as MutableList).addAll(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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// ignore
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}
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}
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return Pair(false, mutableListOf())
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}
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private fun parseResolvConfNameservers(`in`: InputStream): MutableList<InetSocketAddress> {
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val defaultNameServers = mutableListOf<InetSocketAddress>()
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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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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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"nameserver" -> defaultNameServers.add(InetSocketAddress(st.nextToken(), 53))
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}
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}
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Common.logger.error("Error parsing $path", e)
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}
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}
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return defaultNameServers
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return Pair(false, mutableMapOf())
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}
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/**
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@ -379,4 +449,26 @@ object Dns {
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return 1
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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 socketAddress(hostname: String, port: Int): InetSocketAddress {
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return AccessController.doPrivileged(PrivilegedAction { InetSocketAddress(hostname, port) })
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}
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}
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