Class UnixResolverDnsServerAddressStreamProvider

java.lang.Object

io.netty.resolver.dns.UnixResolverDnsServerAddressStreamProvider

All Implemented Interfaces:

DnsServerAddressStreamProvider

public final class UnixResolverDnsServerAddressStreamProvider
extends Object
implements DnsServerAddressStreamProvider

Able to parse files such as /etc/resolv.conf and /etc/resolver to respect the system default domain servers.

Field Summary

Fields

Modifier and Type	Field	Description
private final DnsServerAddresses	defaultNameServerAddresses
private static final String	DOMAIN_ROW_LABEL
private final Map<String, DnsServerAddresses>	domainToNameServerStreamMap
private static final String	ETC_RESOLV_CONF_FILE
private static final String	ETC_RESOLVER_DIR
private static final InternalLogger	logger
private static final String	NAMESERVER_ROW_LABEL
private static final String	OPTIONS_ROTATE_FLAG
private static final String	OPTIONS_ROW_LABEL
private static final String	PORT_ROW_LABEL
private static final String	RES_OPTIONS
private static final String	SEARCH_ROW_LABEL
private static final String	SORTLIST_ROW_LABEL
private static final Pattern	WHITESPACE_PATTERN

Constructor Summary

Constructors

Constructor	Description
UnixResolverDnsServerAddressStreamProvider(File etcResolvConf, File... etcResolverFiles)	Parse a file of the format /etc/resolv.conf which may contain the default DNS server to use, and also overrides for individual domains.
UnixResolverDnsServerAddressStreamProvider(String etcResolvConf, String etcResolverDir)	Parse a file of the format /etc/resolv.conf which may contain the default DNS server to use, and also overrides for individual domains.

Method Summary

Modifier and Type	Method	Description
private boolean	mayOverrideNameServers()
DnsServerAddressStream	nameServerAddressStream(String hostname)	Ask this provider for the name servers to query for hostname.
private static Map<String, DnsServerAddresses>	parse(File... etcResolverFiles)
(package private) static UnixResolverOptions	parseEtcResolverOptions()	Parse /etc/resolv.conf and return options of interest, namely: timeout, attempts and ndots.
(package private) static UnixResolverOptions	parseEtcResolverOptions(File etcResolvConf)	Parse a file of the format /etc/resolv.conf and return options of interest, namely: timeout, attempts and ndots.
(package private) static List<String>	parseEtcResolverSearchDomains()	Parse a file of the format /etc/resolv.conf and return the list of search domains found in it or an empty list if not found.
(package private) static List<String>	parseEtcResolverSearchDomains(File etcResolvConf)	Parse a file of the format /etc/resolv.conf and return the list of search domains found in it or an empty list if not found.
private static int	parseResIntOption(String opt, String fullLabel)
private static void	parseResOptions(String line, UnixResolverOptions.Builder builder)
(package private) static DnsServerAddressStreamProvider	parseSilently()	Attempt to parse /etc/resolv.conf and files in the /etc/resolver directory by default.
private static void	putIfAbsent(Map<String, DnsServerAddresses> domainToNameServerStreamMap, String domainName, DnsServerAddresses addresses)
private static void	putIfAbsent(Map<String, DnsServerAddresses> domainToNameServerStreamMap, String domainName, List<InetSocketAddress> addresses, boolean rotate)

Methods inherited from class Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Details

logger

private static final InternalLogger logger

WHITESPACE_PATTERN

private static final Pattern WHITESPACE_PATTERN

RES_OPTIONS

private static final String RES_OPTIONS

ETC_RESOLV_CONF_FILE

private static final String ETC_RESOLV_CONF_FILE

See Also:

• Constant Field Values

ETC_RESOLVER_DIR

private static final String ETC_RESOLVER_DIR

See Also:

• Constant Field Values

NAMESERVER_ROW_LABEL

private static final String NAMESERVER_ROW_LABEL

See Also:

• Constant Field Values

SORTLIST_ROW_LABEL

private static final String SORTLIST_ROW_LABEL

See Also:

• Constant Field Values

OPTIONS_ROW_LABEL

private static final String OPTIONS_ROW_LABEL

See Also:

• Constant Field Values

OPTIONS_ROTATE_FLAG

private static final String OPTIONS_ROTATE_FLAG

See Also:

• Constant Field Values

DOMAIN_ROW_LABEL

private static final String DOMAIN_ROW_LABEL

See Also:

• Constant Field Values

SEARCH_ROW_LABEL

private static final String SEARCH_ROW_LABEL

See Also:

• Constant Field Values

PORT_ROW_LABEL

private static final String PORT_ROW_LABEL

See Also:

• Constant Field Values

defaultNameServerAddresses

private final DnsServerAddresses defaultNameServerAddresses

domainToNameServerStreamMap

private final Map<String, DnsServerAddresses> domainToNameServerStreamMap

Constructor Details

UnixResolverDnsServerAddressStreamProvider

public UnixResolverDnsServerAddressStreamProvider(File etcResolvConf,
 File... etcResolverFiles)
                                           throws IOException

Parse a file of the format /etc/resolv.conf which may contain the default DNS server to use, and also overrides for individual domains. Also parse list of files of the format /etc/resolver which may contain multiple files to override the name servers used for multiple domains.

Parameters:

etcResolvConf - /etc/resolv.conf.

etcResolverFiles - List of files of the format defined in /etc/resolver.

Throws:

IOException - If an error occurs while parsing the input files.

UnixResolverDnsServerAddressStreamProvider

public UnixResolverDnsServerAddressStreamProvider(String etcResolvConf,
 String etcResolverDir)
                                           throws IOException

Parse a file of the format /etc/resolv.conf which may contain the default DNS server to use, and also overrides for individual domains. Also parse a directory of the format /etc/resolver which may contain multiple files to override the name servers used for multiple domains.

Parameters:

etcResolvConf - /etc/resolv.conf.

etcResolverDir - Directory containing files of the format defined in /etc/resolver.

Throws:

IOException - If an error occurs while parsing the input files.

Method Details

parseSilently

static DnsServerAddressStreamProvider parseSilently()

Attempt to parse /etc/resolv.conf and files in the /etc/resolver directory by default. A failure to parse will return DefaultDnsServerAddressStreamProvider.

nameServerAddressStream

public DnsServerAddressStream nameServerAddressStream(String hostname)

Description copied from interface: DnsServerAddressStreamProvider

Ask this provider for the name servers to query for hostname.

Specified by:

nameServerAddressStream in interface DnsServerAddressStreamProvider

Parameters:

hostname - The hostname for which to lookup the DNS server addressed to use. If this is the final DnsServerAddressStreamProvider to be queried then generally empty string or '.' correspond to the default DnsServerAddressStream.

Returns:

The DnsServerAddressStream which should be used to resolve hostname.

mayOverrideNameServers

private boolean mayOverrideNameServers()

parse

private static Map<String, DnsServerAddresses> parse(File... etcResolverFiles)
                                              throws IOException

Throws:

IOException

putIfAbsent

private static void putIfAbsent(Map<String, DnsServerAddresses> domainToNameServerStreamMap,
 String domainName,
 List<InetSocketAddress> addresses,
 boolean rotate)

putIfAbsent

private static void putIfAbsent(Map<String, DnsServerAddresses> domainToNameServerStreamMap,
 String domainName,
 DnsServerAddresses addresses)

parseEtcResolverOptions

static UnixResolverOptions parseEtcResolverOptions()
                                            throws IOException

Parse /etc/resolv.conf and return options of interest, namely: timeout, attempts and ndots.

Returns:

The options values provided by /etc/resolve.conf.

Throws:

IOException - If a failure occurs parsing the file.

parseEtcResolverOptions

static UnixResolverOptions parseEtcResolverOptions(File etcResolvConf)
                                            throws IOException

Parse a file of the format /etc/resolv.conf and return options of interest, namely: timeout, attempts and ndots.

Parameters:

etcResolvConf - a file of the format /etc/resolv.conf.

Returns:

The options values provided by /etc/resolve.conf.

Throws:

IOException - If a failure occurs parsing the file.

parseResOptions

private static void parseResOptions(String line,
 UnixResolverOptions.Builder builder)

parseResIntOption

private static int parseResIntOption(String opt,
 String fullLabel)

parseEtcResolverSearchDomains

static List<String> parseEtcResolverSearchDomains()
                                           throws IOException

Parse a file of the format /etc/resolv.conf and return the list of search domains found in it or an empty list if not found.

Returns:

List of search domains.

Throws:

IOException - If a failure occurs parsing the file.

parseEtcResolverSearchDomains

static List<String> parseEtcResolverSearchDomains(File etcResolvConf)
                                           throws IOException

Parse a file of the format /etc/resolv.conf and return the list of search domains found in it or an empty list if not found.

Parameters:

etcResolvConf - a file of the format /etc/resolv.conf.

Returns:

List of search domains.

Throws:

IOException - If a failure occurs parsing the file.