Package org.xbill.DNS.hosts

Class HostsFileParser

java.lang.Object

org.xbill.DNS.hosts.HostsFileParser

public final class HostsFileParser
extends Object

Parses and caches the system's local hosts database, otherwise known as /etc/hosts. The cache is cleared when the file is modified.

Since:

3.4

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
private static final class	HostsFileParser.LineData

Field Summary

Fields

Modifier and Type	Field	Description
private final boolean	clearCacheOnChange
private Clock	clock
private final Duration	fileChangeCheckInterval
private Map<String,InetAddress>	hostsCache
private long	hostsFileSizeBytes
private boolean	hostsFileWarningLogged
private boolean	isEntireFileParsed
private Instant	lastFileModificationCheckTime
private Instant	lastFileReadTime
private final int	maxFullCacheFileSizeBytes
private final Path	path

Constructor Summary

Constructors

Constructor	Description
HostsFileParser()	Creates a new instance based on the current OS's default.
HostsFileParser(Path path)	Creates an instance with a custom hosts database path.
HostsFileParser(Path path, boolean clearCacheOnChange)	Creates an instance with a custom hosts database path.

Method Summary

Modifier and Type	Method	Description
(package private) int	cacheSize()
private void	createOrClearCache()
Optional<InetAddress>	getAddressForHost(Name name, int type)	Performs on-demand parsing and caching of the local hosts database.
private String[]	getLineTokens(String line)
private String	key(Name name, int type)
private void	parseEntireHostsFile()
private HostsFileParser.LineData	parseLine(int lineNumber, String line, AtomicInteger addressFailures, AtomicInteger nameFailures)
private void	readHostsFile()
private Name	safeName(String name, int lineNumber, AtomicInteger nameFailures)
private void	searchHostsFileForEntry(Name name, int type)
(package private) void	setClock(Clock clock)
private void	validateCache()

Methods inherited from class java.lang.Object

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

Field Details

maxFullCacheFileSizeBytes

private final int maxFullCacheFileSizeBytes

fileChangeCheckInterval

private final Duration fileChangeCheckInterval

path

private final Path path

clearCacheOnChange

private final boolean clearCacheOnChange

clock

private Clock clock

hostsCache

private volatile Map<String,InetAddress> hostsCache

lastFileModificationCheckTime

private Instant lastFileModificationCheckTime

lastFileReadTime

private Instant lastFileReadTime

isEntireFileParsed

private boolean isEntireFileParsed

hostsFileWarningLogged

private boolean hostsFileWarningLogged

hostsFileSizeBytes

private long hostsFileSizeBytes

Constructor Details

HostsFileParser

public HostsFileParser()

Creates a new instance based on the current OS's default. Unix and alike (or rather everything else than Windows) use /etc/hosts, while on Windows %SystemRoot%\System32\drivers\etc\hosts is used. The cache is cleared when the file has changed.

HostsFileParser

public HostsFileParser(Path path)

Creates an instance with a custom hosts database path. The cache is cleared when the file has changed.

Parameters:

path - The path to the hosts database.

HostsFileParser

public HostsFileParser(Path path,
 boolean clearCacheOnChange)

Creates an instance with a custom hosts database path.

Parameters:

path - The path to the hosts database.

clearCacheOnChange - set to true to clear the cache when the hosts file changes.

Method Details

getAddressForHost

public Optional<InetAddress> getAddressForHost(Name name,
 int type)
                                        throws IOException

Performs on-demand parsing and caching of the local hosts database.

Parameters:

name - the hostname to search for.

type - Record type to search for, see Type.

Returns:

The first address found for the requested hostname.

Throws:

IOException - When the parsing fails.

IllegalArgumentException - when type is not Type.A orType.AAAA.

parseEntireHostsFile

private void parseEntireHostsFile()
                           throws IOException

Throws:

IOException

searchHostsFileForEntry

private void searchHostsFileForEntry(Name name,
 int type)
                              throws IOException

Throws:

IOException

parseLine

private HostsFileParser.LineData parseLine(int lineNumber,
 String line,
 AtomicInteger addressFailures,
 AtomicInteger nameFailures)

safeName

private Name safeName(String name,
 int lineNumber,
 AtomicInteger nameFailures)

getLineTokens

private String[] getLineTokens(String line)

validateCache

private void validateCache()
                    throws IOException

Throws:

IOException

readHostsFile

private void readHostsFile()
                    throws IOException

Throws:

IOException

createOrClearCache

private void createOrClearCache()

key

private String key(Name name,
 int type)

cacheSize

int cacheSize()

setClock

void setClock(Clock clock)