/*
* RHQ Management Platform
* Copyright (C) 2005-2009 Red Hat, Inc.
* All rights reserved.
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License, version 2, as
* published by the Free Software Foundation, and/or the GNU Lesser
* General Public License, version 2.1, also as published by the Free
* Software Foundation.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License and the GNU Lesser General Public License
* for more details.
*
* You should have received a copy of the GNU General Public License
* and the GNU Lesser General Public License along with this program;
* if not, write to the Free Software Foundation, Inc.,
* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
*/
package org.rhq.plugins.hosts.helper;
import java.io.File;
import java.io.FileOutputStream;
import java.io.FileReader;
import java.io.FileWriter;
import java.io.IOException;
import java.io.PrintWriter;
import java.util.Collections;
import java.util.HashMap;
import java.util.HashSet;
import java.util.LinkedHashSet;
import java.util.Map;
import java.util.Set;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.jetbrains.annotations.Nullable;
/**
* A set of hosts file entries.
*
* @author Ian Springer
*/
public class Hosts {
private static final Log LOG = LogFactory.getLog(Hosts.class);
private Set<HostsEntry> entries = new LinkedHashSet<HostsEntry>();
private Map<String, Set<HostsEntry>> nameToIpv4EntriesMap = new HashMap<String, Set<HostsEntry>>();
private Map<String, Set<HostsEntry>> nameToIpv6EntriesMap = new HashMap<String, Set<HostsEntry>>();
public Hosts() {
}
public void addEntry(HostsEntry entry) {
this.entries.add(entry);
String canonicalName = entry.getCanonicalName();
updateNameToEntriesMaps(entry, canonicalName);
}
private void updateNameToEntriesMaps(HostsEntry entry, String canonicalName) {
Map<String, Set<HostsEntry>> nameToEntriesMap = (entry.getIpVersion() == 4) ?
this.nameToIpv4EntriesMap : this.nameToIpv6EntriesMap;
Set<HostsEntry> entriesForCanonicalName = nameToEntriesMap.get(canonicalName);
if (entriesForCanonicalName == null) {
entriesForCanonicalName = new LinkedHashSet(1);
nameToEntriesMap.put(canonicalName, entriesForCanonicalName);
}
entriesForCanonicalName.add(entry);
}
public Set<HostsEntry> getEntries() {
return this.entries;
}
public Set<HostsEntry> getIpv4EntriesByName(String canonicalName) {
Set<HostsEntry> entries = this.nameToIpv4EntriesMap.get(canonicalName);
return (entries != null) ? entries : Collections.<HostsEntry> emptySet();
}
public Set<HostsEntry> getIpv6EntriesByName(String canonicalName) {
Set<HostsEntry> entries = this.nameToIpv6EntriesMap.get(canonicalName);
return (entries != null) ? entries : Collections.<HostsEntry> emptySet();
}
public static Hosts load(File hostsFile) throws IOException {
Hosts hosts = new Hosts();
SimpleUnixConfigFileReader reader = new SimpleUnixConfigFileReader(new FileReader(hostsFile));
try {
SimpleUnixConfigFileLine line;
while ((line = reader.readLine()) != null) {
String nonComment = line.getNonComment();
HostsEntry entry = parseEntry(nonComment, hostsFile);
if (entry != null) {
hosts.addEntry(entry);
}
}
} finally {
reader.close();
}
return hosts;
}
public static void store(Hosts hosts, File hostsFile) throws IOException {
if (!hostsFile.exists()) {
// If a hosts file doesn't already exist, create an empty one.
FileOutputStream hostsFileWriter = new FileOutputStream(hostsFile);
hostsFileWriter.close();
}
Set<String> storedIpv4CanonicalNames = new HashSet<String>();
Set<String> storedIpv6CanonicalNames = new HashSet<String>();
File newHostsFile = new File(hostsFile.getPath() + "-" + System.currentTimeMillis());
PrintWriter newHostsFileWriter = new PrintWriter(new FileWriter(newHostsFile));
try {
SimpleUnixConfigFileLine line;
SimpleUnixConfigFileReader hostsFileReader = new SimpleUnixConfigFileReader(new FileReader(hostsFile));
try {
while ((line = hostsFileReader.readLine()) != null) {
StringBuilder newLine = createNewLine(hosts, hostsFile, line, storedIpv4CanonicalNames,
storedIpv6CanonicalNames);
if (newLine != null) {
newHostsFileWriter.println(newLine);
}
}
} finally {
hostsFileReader.close();
}
// Write out any entries for IP addresses that did not have entries in the original file.
for (HostsEntry newEntry : hosts.getEntries()) {
Set<String> storedCanonicalNames = (newEntry.getIpVersion() == 4) ? storedIpv4CanonicalNames :
storedIpv6CanonicalNames;
if (!storedCanonicalNames.contains(newEntry.getCanonicalName())) {
StringBuilder newLine = new StringBuilder(newEntry.getIpAddress()).append("\t").append(
newEntry.getCanonicalName());
for (String alias : newEntry.getAliases()) {
newLine.append("\t").append(alias);
}
newHostsFileWriter.println(newLine);
}
}
} finally {
newHostsFileWriter.close();
}
// Backup the original hosts file (e.g. /etc/hosts) to hosts~ (e.g. /etc/hosts~).
File backupHostsFile = new File(hostsFile.getPath() + "~");
if (backupHostsFile.exists()) {
// renameTo() will fail on Windows if the destination file already exists. Lame, eh?
boolean deleteSucceeded = backupHostsFile.delete();
}
boolean backupSucceeded = hostsFile.renameTo(backupHostsFile);
if (!backupSucceeded) {
throw new IOException("Failed to backup original hosts file [" + hostsFile + "] to [" + backupHostsFile
+ "].");
}
// And finally, rename the new hosts file (e.g. /etc/hosts-1234567890) to the actual hosts file (e.g. /etc/hosts).
if (hostsFile.exists()) {
// renameTo() will fail on Windows if the destination file already exists. Lame, eh?
boolean deleteSucceeded = hostsFile.delete();
}
boolean updateSucceeded = newHostsFile.renameTo(hostsFile);
if (!updateSucceeded) {
throw new IOException("Failed to rename updated hosts file [" + newHostsFile + "] to [" + hostsFile + "].");
}
return;
}
private static HostsEntry parseEntry(String string, File hostsFile) {
if (string == null) {
// comment-only line
return null;
}
String trimmedString = string.trim();
if (trimmedString.equals("")) {
// comment-only line
return null;
}
String[] tokens = trimmedString.split("\\s+");
if (tokens.length == 0) {
// comment-only line
return null;
}
String ipAddress = tokens[0];
if (tokens.length == 1) {
LOG.warn("Hosts file [" + hostsFile + "] contains invalid entry for IP address " + ipAddress
+ " - no canonical name is specified.");
}
String canonicalName = null;
Set<String> aliasSet = null;
if (tokens.length >= 2) {
canonicalName = tokens[1];
if (tokens.length >= 3) {
aliasSet = new LinkedHashSet<String>(tokens.length - 2);
for (int i = 2; i < tokens.length; i++) {
aliasSet.add(tokens[i]);
}
}
}
return new HostsEntry(ipAddress, canonicalName, aliasSet);
}
@Nullable
private static StringBuilder createNewLine(Hosts hosts, File hostsFile, SimpleUnixConfigFileLine existingLine,
Set<String> storedIpv4CanonicalNames,
Set<String> storedIpv6CanonicalNames) {
StringBuilder newLine;
String nonComment = existingLine.getNonComment();
String comment = existingLine.getComment();
HostsEntry existingEntry = parseEntry(nonComment, hostsFile);
if (existingEntry != null) {
Set<HostsEntry> newEntries = (existingEntry.getIpVersion() == 4) ?
hosts.getIpv4EntriesByName(existingEntry.getCanonicalName()) :
hosts.getIpv6EntriesByName(existingEntry.getCanonicalName());
// TODO: Look up entries for existing entry's aliases too?
if (!newEntries.isEmpty()) {
// replace the existing entry
HostsEntry newEntry = newEntries.iterator().next();
LOG.debug("Replacing existing entry in hosts file [" + existingEntry + "] with new entry [" + newEntry
+ "]...");
newLine = new StringBuilder(newEntry.getIpAddress()).append("\t").append(newEntry.getCanonicalName());
for (String alias : newEntry.getAliases()) {
newLine.append("\t").append(alias);
}
// but still write out the existing comment
if (comment != null) {
newLine.append(" #").append(comment);
}
Set<String> storedCanonicalNames = (newEntry.getIpVersion() == 4) ? storedIpv4CanonicalNames :
storedIpv6CanonicalNames;
storedCanonicalNames.add(newEntry.getCanonicalName());
} else {
LOG.debug("Removing entry [" + existingEntry + "] from hosts file...");
newLine = null;
}
} else {
// comment-only line - write it back out exactly as is
newLine = new StringBuilder();
if (nonComment != null) {
newLine.append(nonComment);
}
if (comment != null) {
newLine.append('#').append(comment);
}
}
return newLine;
}
}